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  <front>
    <journal-meta>
      <journal-id journal-id-type="nlm-ta">Arq Bras Cardiol</journal-id>
      <journal-id journal-id-type="publisher-id">abc</journal-id>
      <journal-title-group>
        <journal-title>Arquivos Brasileiros de Cardiologia</journal-title>
        <abbrev-journal-title abbrev-type="publisher">Arq. Bras. Cardiol.</abbrev-journal-title>
      </journal-title-group>
      <issn pub-type="ppub">0066-782X</issn>
      <issn pub-type="epub">1678-4170</issn>
      <publisher>
        <publisher-name>Sociedade Brasileira de Cardiologia - SBC</publisher-name>
      </publisher>
    </journal-meta>
    <article-meta>
      <article-id specific-use="scielo-v3" pub-id-type="publisher-id">gbpW9NJcDPggXZfpPBQsTrd</article-id>
      <article-id specific-use="scielo-v2" pub-id-type="publisher-id">S0066-782X2021001200715</article-id>
      <article-id pub-id-type="publisher-id">abc.20200044</article-id>
      <article-id pub-id-type="doi">10.36660/abc.20200044</article-id>
      <article-categories>
        <subj-group subj-group-type="heading">
          <subject>Artigo Original</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>Novo Efeito Cardioprotetor da L-Carnitina em Camundongos Obesos Diab&#233;ticos: Regula&#231;&#227;o da Express&#227;o de Quemerina e CMKLRI no Cora&#231;&#227;o e Tecidos Adiposos</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <name>
            <surname>Amiri</surname>
            <given-names>Rezvan</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">
            <sup>1</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0003-3258-8550</contrib-id>
          <name>
            <surname>Tabandeh</surname>
            <given-names>Mohammad Reza</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">
            <sup>1</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Hosseini</surname>
            <given-names>Seyed Ahmad</given-names>
          </name>
          <xref ref-type="aff" rid="aff2">
            <sup>2</sup>
          </xref>
        </contrib>
      </contrib-group>
      <aff id="aff1">
        <label>1</label>
        <institution content-type="orgdiv2">Department of Basic Sciences</institution>
        <institution content-type="orgdiv1">Faculty of Veterinary Medicine</institution>
        <institution content-type="orgname">Shahid Chamran University of Ahvaz</institution>
        <addr-line>
          <named-content content-type="city">Ahvaz</named-content>
        </addr-line>
        <country country="IR">Ir&#227;</country>
        <institution content-type="original">Department of Basic Sciences, Division of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz &#8211; Ir&#227;</institution>
      </aff>
      <aff id="aff2">
        <label>2</label>
        <institution content-type="orgdiv1">Department of Nutrition Science</institution>
        <institution content-type="orgname">Ahvaz Jundishapur University of Medical Sciences</institution>
        <addr-line>
          <named-content content-type="city">Ahvaz</named-content>
        </addr-line>
        <country country="IR">Ir&#227;</country>
        <institution content-type="original">Department of Nutrition Science, Ahvaz Jundishapur University of Medical Sciences, Ahvaz &#8211; Ir&#227;</institution>
      </aff>
      <author-notes>
        <corresp id="c01"> Correspond&#234;ncia: Mohammad Reza Tabandeh &#8226; Department of Basic Sciences, Division of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, 61355-145, Ahvaz, Ir&#227; E-mail: <email>m.tabandeh@scu.ac.ir</email> </corresp>
        <fn fn-type="con">
          <p>Contribui&#231;&#227;o dos autores</p>
          <p>Concep&#231;&#227;o e desenho da pesquisa: Tabandeh MR, Hosseini SA; Obten&#231;&#227;o de dados: Amiri R; An&#225;lise e interpreta&#231;&#227;o dos dados: Amiri R, Tabandeh MR, Hosseini SA; An&#225;lise estat&#237;stica: Amiri R, Tabandeh MR, Hosseini SA; Obten&#231;&#227;o de financiamento e Revis&#227;o cr&#237;tica do manuscrito quanto ao conte&#250;do intelectual importante: Tabandeh MR; Reda&#231;&#227;o do manuscrito: Amiri R, Tabandeh MR.</p>
        </fn>
        <fn fn-type="conflict">
          <p>Potencial conflito de interesse</p>
          <p>N&#227;o h&#225; conflito com o presente artigo</p>
        </fn>
      </author-notes>
      <pub-date date-type="pub" publication-format="electronic">
        <day>25</day>
        <month>10</month>
        <year>2021</year>
      </pub-date>
      <pub-date date-type="collection" publication-format="electronic">
        <month>10</month>
        <year>2021</year>
      </pub-date>
      <volume>117</volume>
      <issue>4</issue>
      <fpage>715</fpage>
      <lpage>725</lpage>
      <history>
        <date date-type="received">
          <day>25</day>
          <month>01</month>
          <year>2020</year>
        </date>
        <date date-type="rev-recd">
          <day>14</day>
          <month>08</month>
          <year>2020</year>
        </date>
        <date date-type="accepted">
          <day>30</day>
          <month>09</month>
          <year>2020</year>
        </date>
      </history>
      <permissions>
        <license license-type="open-access" xlink:href="https://creativecommons.org/licenses/by/4.0/" xml:lang="en">
          <license-p> This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. </license-p>
        </license>
      </permissions>
      <abstract>
        <title>Resumo</title>
        <sec>
          <title>Fundamentos</title>
          <p> A L-carnitina (LC) tem muitos efeitos ben&#233;ficos em animais diab&#233;ticos e humanos, mas seu efeito regulat&#243;rio sobre a quemerina como uma citocina inflamat&#243;ria e seu receptor no estado diab&#233;tico s&#227;o desconhecidos.</p>
        </sec>
        <sec>
          <title>Objetivos</title>
          <p> O presente estudo teve como objetivo investigar o efeito regulat&#243;rio da LC na express&#227;o do receptor semelhante ao de quimiocina 1 e quemerina (CMKLRI) em tecidos adiposo e card&#237;aco de camundongos diab&#233;ticos.</p>
        </sec>
        <sec>
          <title>M&#233;todos</title>
          <p> Sessenta camundongos NMARI foram divididos em quatro grupos, incluindo controle, diab&#233;tico, diab&#233;tico + suplementa&#231;&#227;o com LC e controle + suplementa&#231;&#227;o com LC. O diabetes foi induzido pela alimenta&#231;&#227;o dos animais com dieta hipercal&#243;rica por 5 semanas e inje&#231;&#227;o de estreptozotocina. Os animais foram tratados com 300 mg/kg de LC por 28 dias. Nos dias 7, 14 e 28 ap&#243;s o tratamento, os n&#237;veis de mRNA e prote&#237;na da quemerina e CMKLRI nos tecidos card&#237;acos e adiposos de animais foram determinados utilizando an&#225;lise por qPCR e ELISA. Os &#237;ndices de resist&#234;ncia &#224; insulina tamb&#233;m foram medidos em todos os grupos experimentais. A diferen&#231;a com p&lt;0,05 foi considerada significativa.</p>
        </sec>
        <sec>
          <title>Resultados</title>
          <p> A express&#227;o de quemerina e CMKLRI aumentou nos tecidos card&#237;aco e adiposo de camundongos diab&#233;ticos nos dias 14 e 28 ap&#243;s a indu&#231;&#227;o do diabetes, concomitantemente com a incid&#234;ncia de resist&#234;ncia &#224; insulina e n&#237;veis aumentados de quemerina circulante (p&lt;0,05). O tratamento com LC causou uma diminui&#231;&#227;o significativa na express&#227;o de ambos os genes nos tecidos estudados e redu&#231;&#227;o dos sintomas de resist&#234;ncia &#224; insulina e dos n&#237;veis s&#233;ricos de quemerina (p&lt;0,05).</p>
        </sec>
        <sec>
          <title>Conclus&#227;o</title>
          <p> Os resultados sugerem que o tratamento com LC pode diminuir a express&#227;o de quemerina e CKLR1 em tecidos card&#237;acos e adiposos de animais experimentais obesos e diab&#233;ticos.</p>
        </sec>
      </abstract>
      <kwd-group xml:lang="pt">
        <kwd>Diabetes Mellitus</kwd>
        <kwd>Carnitina</kwd>
        <kwd>Quimiocinas</kwd>
      </kwd-group>
      <counts>
        <fig-count count="10"/>
        <table-count count="10"/>
        <equation-count count="0"/>
        <ref-count count="35"/>
        <page-count count="11"/>
      </counts>
    </article-meta>
  </front>
  <body>
    <sec sec-type="intro">
      <title>Introdu&#231;&#227;o</title>
      <p>Um n&#250;mero crescente de evid&#234;ncias tem mostrado a exist&#234;ncia de uma rela&#231;&#227;o bioqu&#237;mica e molecular complexa e multifacetada entre diabetes mellitus (DM), obesidade e doen&#231;as cardiovasculares (DCV).<sup><xref ref-type="bibr" rid="B1">1</xref></sup> Um poss&#237;vel mecanismo que liga DM e obesidade com DCV subsequentes &#233; a inflama&#231;&#227;o de baixo grau em tecido adiposo.<sup><xref ref-type="bibr" rid="B2">2</xref></sup> O tecido adiposo de animais ou humanos com DM e resist&#234;ncia &#224; insulina secreta uma variedade de citocinas ou adipocinas. A secre&#231;&#227;o anormal dessas adipocinas contribui para o aumento da inflama&#231;&#227;o e do ac&#250;mulo de l&#237;pides e pode levar ao desenvolvimento de disfun&#231;&#227;o endotelial e mioc&#225;rdica e cardiomiopatias.<sup><xref ref-type="bibr" rid="B2">2</xref> , <xref ref-type="bibr" rid="B3">3</xref></sup> As altera&#231;&#245;es de express&#227;o ou secre&#231;&#227;o de adipocinas pr&#243;-inflamat&#243;rias e anti-inflamat&#243;rias em cardiomi&#243;citos e tecido adiposo t&#234;m sido implicadas na patog&#234;nese da s&#237;ndrome metab&#243;lica e DCV em animais ou humanos obesos.<sup><xref ref-type="bibr" rid="B2">2</xref></sup></p>
      <p>A quemerina &#233; uma adipocina recentemente identificada que atua como uma prote&#237;na quimioatrativa e medeia seus efeitos atrav&#233;s de um receptor acoplado &#224; prote&#237;na G, o receptor semelhante ao de quimiocina 1 (CMKLRI, do ingl&#234;s <italic>chemokine like receptor 1</italic> ), tamb&#233;m conhecido como ChemR23.<sup><xref ref-type="bibr" rid="B4">4</xref> - <xref ref-type="bibr" rid="B7">7</xref></sup> Estudos anteriores demonstraram que a quemerina tinha um papel em v&#225;rias patologias cardiovasculares, incluindo o desenvolvimento de hipertens&#227;o, progress&#227;o de les&#245;es ateroscler&#243;ticas e fun&#231;&#227;o card&#237;aca prejudicada em pacientes com cardiomiopatia dilatada.<sup><xref ref-type="bibr" rid="B8">8</xref></sup> A quemerina pode causar inflama&#231;&#227;o endotelial e induzir apoptose em cardiomi&#243;citos murinos, demonstrando o seu papel potencial nas disfun&#231;&#245;es dos cardiomi&#243;citos.<sup><xref ref-type="bibr" rid="B9">9</xref> , <xref ref-type="bibr" rid="B10">10</xref></sup></p>
      <p>Recentemente, nutrientes que t&#234;m como alvo as mitoc&#244;ndrias, como o &#225;cido lip&#243;ico, a L-carnitina (LC), a nicotinamida e a biotina, receberam maior aten&#231;&#227;o na melhora das complica&#231;&#245;es cardiovasculares e inflamat&#243;rias relacionadas ao diabetes.<sup><xref ref-type="bibr" rid="B11">11</xref> , <xref ref-type="bibr" rid="B12">12</xref></sup> A L-carnitina (LC) &#233; condicionalmente um nutriente essencial que facilita o transporte do &#225;cido graxo para os locais de oxida&#231;&#227;o na mitoc&#244;ndria.<sup><xref ref-type="bibr" rid="B13">13</xref> , <xref ref-type="bibr" rid="B14">14</xref></sup></p>
      <p>H&#225; evid&#234;ncias crescentes de que a suplementa&#231;&#227;o de LC pode ser ben&#233;fica no tratamento da resist&#234;ncia &#224; insulina e dist&#250;rbios metab&#243;licos relacionados &#224; obesidade em pacientes diab&#233;ticos.<sup><xref ref-type="bibr" rid="B11">11</xref></sup> V&#225;rios estudos t&#234;m demonstrado que a LC tem efeitos ben&#233;ficos na preven&#231;&#227;o e melhora de doen&#231;as cardiovasculares, incluindo insufici&#234;ncia card&#237;aca cr&#244;nica, infarto agudo do mioc&#225;rdio anterior, doen&#231;a arterial coronariana, remodela&#231;&#227;o mioc&#225;rdica e fibrila&#231;&#227;o atrial.<sup><xref ref-type="bibr" rid="B12">12</xref> , <xref ref-type="bibr" rid="B14">14</xref></sup> V&#225;rios mecanismos t&#234;m sido relatados sobre o papel protetor da LC nas c&#233;lulas card&#237;acas sob condi&#231;&#227;o hiperglic&#234;mica, incluindo melhora da homeostase da energia card&#237;aca, atenua&#231;&#227;o do estresse oxidativo e dano celular hip&#243;xico e redu&#231;&#227;o da apoptose.<sup><xref ref-type="bibr" rid="B15">15</xref> , <xref ref-type="bibr" rid="B16">16</xref></sup> Evid&#234;ncias limitadas tamb&#233;m mostraram que a LC pode afetar a concentra&#231;&#227;o s&#233;rica de quemerina em crian&#231;as obesas.<sup><xref ref-type="bibr" rid="B17">17</xref></sup> Com base em nosso conhecimento, poucos estudos focaram no papel da suplementa&#231;&#227;o de LC na regula&#231;&#227;o da express&#227;o de quemerina, em particular nos tecidos card&#237;acos e adiposos de animais diab&#233;ticos. O objetivo do presente estudo foi investigar os efeitos da suplementa&#231;&#227;o de LC na express&#227;o de quemerina e CMKLRI em tecido adiposo e tecido card&#237;aco de um modelo experimental de obesidade e diabetes induzidos por dieta hipercal&#243;rica em camundongos.</p>
    </sec>
    <sec sec-type="materials|methods">
      <title>Materiais e m&#233;todos</title>
      <sec>
        <title>Animais</title>
        <p>Sessenta camundongos NMARI machos (25 &#177; 2 g) foram selecionados do centro de animais de laborat&#243;rio da faculdade de medicina veterin&#225;ria da Shahid Chamran University de Ahvaz, Ir&#227;. Todos os camundongos foram mantidos em condi&#231;&#245;es ambientais controladas, com temperatura m&#233;dia de 23 &#177; 1&#176;C, ciclo de luz e escurid&#227;o de 12:12 horas, com livre acesso a &#225;gua e dieta especial de camundongos preparada em pellets (Pars, Teer&#227;, Ir&#227;). Todos os protocolos experimentais foram aprovados pelo comit&#234; de &#233;tica para pesquisa em animais e humanos da Shahid Chamran University de Ahvaz (EE/98.24.3.26209/SCU.AC.IR). O trabalho com os camundongos foi realizado com base nas diretrizes para o cuidado e uso de animais de laborat&#243;rio (publica&#231;&#227;o NIH n&#186; 86-23). Eles foram aclimatados por 7 dias antes do in&#237;cio do experimento.</p>
      </sec>
      <sec>
        <title>Desenho experimental</title>
        <p>Os animais (n = 60) foram divididos de forma aleat&#243;ria em quatro grupos igualmente. A randomiza&#231;&#227;o foi realizada por meio da aloca&#231;&#227;o de animais do mesmo sexo, idade e peso em diferentes grupos experimentais atrav&#233;s de tabelas de n&#250;meros aleat&#243;rios. Dois grupos foram alimentados com dieta rica em energia, preparada com adi&#231;&#227;o de 20% de sacarose (p/p) e 10% de banha (p/p) nas dietas por 5 semanas e descritas como tendo alto teor de gordura/hipercal&#243;ricas (HF/HC) (n = 30), enquanto os demais continuaram a consumir dietas normais pelo mesmo per&#237;odo, servindo como grupo controle (n = 30). Ap&#243;s 5 semanas de alimenta&#231;&#227;o com dietas HF/HC, os grupos diab&#233;ticos foram tratados com uma &#250;nica inje&#231;&#227;o intraperitoneal de estreptozotocina (STZ, Sigma, Alemanha) (30 mg/kg de peso corporal) preparada em solu&#231;&#227;o tamp&#227;o de citrato.<sup><xref ref-type="bibr" rid="B18">18</xref> , <xref ref-type="bibr" rid="B19">19</xref></sup></p>
        <p>A glicose foi medida cinco dias ap&#243;s o tratamento com STZ utilizando um glicos&#237;metro port&#225;til (Medisign, China), e a incid&#234;ncia de diabetes foi confirmada se a glicose s&#233;rica estivesse acima de 6,5 mmoL/L e o &#237;ndice HOMA-IR estivesse aumentado em compara&#231;&#227;o com o grupo de controle.<sup><xref ref-type="bibr" rid="B20">20</xref></sup> O dia seguinte ap&#243;s a confirma&#231;&#227;o do diabetes foi considerado o dia 0 do tratamento com LC. Um grupo diab&#233;tico foi tratado com LC na dose de 300 mg/kg (n = 15) em &#225;gua pot&#225;vel concomitante com a dieta HF/HC por 28 dias, enquanto outro grupo diab&#233;tico (n = 15) (controle diab&#233;tico) foi alimentado apenas com a dieta HF/HC pelo mesmo per&#237;odo.<sup><xref ref-type="bibr" rid="B18">18</xref> , <xref ref-type="bibr" rid="B19">19</xref></sup> Tamb&#233;m foram considerados um grupo controle (n = 15) que recebeu dieta normal e outro grupo controle (n = 15) (controle tratado com LC) que consumiu LC na dose de 300 mg/kg em &#225;gua pot&#225;vel por 28 dias.</p>
      </sec>
      <sec>
        <title>Amostragem</title>
        <p>A eutan&#225;sia dos animais foi realizada com uma combina&#231;&#227;o de cetamina (100 mg/kg) e xilazina (10 mg/kg), respectivamente, nos dias 0, 14 e 28 ap&#243;s o tratamento com LC. Amostras de sangue foram coletadas e os soros separados e armazenados a -20&#176;C para utiliza&#231;&#227;o. O cora&#231;&#227;o e o tecido adiposo visceral foram separados e mantidos a &#8211;70&#176;C at&#233; a sua utiliza&#231;&#227;o.</p>
      </sec>
      <sec>
        <title>Medidas de par&#226;metros bioqu&#237;micos</title>
        <p>Os n&#237;veis s&#233;ricos de insulina e quemerina foram determinados com os kits ELISA espec&#237;ficos para a esp&#233;cie (EastBiopharm, China). A glicose s&#233;rica foi medida com kits comerciais (PishtazTeb, Ir&#227;) de acordo com a recomenda&#231;&#227;o do fabricante. As concentra&#231;&#245;es s&#233;ricas de IL1-&#946; e TNF-&#945; foram determinadas utilizando kits ELISA espec&#237;ficos para a esp&#233;cie, conforme recomendado pelo fabricante (Biovision Inc. EUA)</p>
      </sec>
      <sec>
        <title>Estimativa de HOMA &#8211; IR</title>
        <p>O &#237;ndice HOMA-IR foi calculado utilizando a seguinte f&#243;rmula:</p>
        <p>&#205;ndice HOMA = Insulina em jejum (&#181;U/ml) &#215; Glicose em jejum (mmol/L)/22,5. Valores crescentes e decrescentes de HOMA-IR em rela&#231;&#227;o ao controle, animais saud&#225;veis indicam aumento e diminui&#231;&#227;o na sensibilidade &#224; insulina, respectivamente.<sup><xref ref-type="bibr" rid="B20">20</xref></sup></p>
      </sec>
      <sec>
        <title>Isolamento de RNA e s&#237;ntese de cDNA</title>
        <p>O RNA total foi extra&#237;do de 100 mg de cora&#231;&#227;o e tecidos adiposos utilizando o reagente de isolamento RNX<sup>&#174;</sup> de acordo com o procedimento do fabricante (SinaClon, Teer&#227;, Ir&#227;). As amostras foram tratadas com a enzima DNase I para evitar contamina&#231;&#227;o do DNA. A pureza do RNA na raz&#227;o 260/280 OD e a integridade do RNA foram avaliadas com uma c&#233;lula de medi&#231;&#227;o de microvolume em Eppendorf &#181;Cuvette G1.0 (Eppendorf BioPhotometer D30, Eppendorf, Alemanha). A transcri&#231;&#227;o reversa foi realizada com o kit de s&#237;ntese de cDNA YTA (Yekta tajhiz, Ir&#227;) e Eppendorf Thermal Cycler (Alemanha) utilizando 1 &#181;g de RNA e hex&#226;mero aleat&#243;rio, conforme recomendado pelo fabricante.</p>
      </sec>
      <sec>
        <title>PCR quantitativa em tempo real (RT-PCR)</title>
        <p>A rea&#231;&#227;o em cadeia da polimerase (PCR, do ingl&#234;s <italic>Polymerase Chain Reaction</italic> ) em tempo real foi realizada utilizando o sistema de detec&#231;&#227;o Roche Light-Cycler (Basel, Su&#237;&#231;a) pelo qPCR<sup>&#174;</sup> Green Master Kit para SYBR Green I<sup>&#174;</sup> (Yektatajhiz, Ir&#227;). O n&#237;vel de express&#227;o relativa dos transcritos de quemerina e CMKLRI foram comparados com os de camundongos GAPDH como gene <italic>housekeeping</italic> . Os conjuntos espec&#237;ficos de primers (Pishgam BioTech, Co, Teer&#227;, Ir&#227;) projetados para este estudo foram: quemerina (GenBank:NC-007299): 5&#8217;- TCTTCACCTACGACCAGTATCAG -3&#8217; e 5&#8217;- ACATTATCTGCATAGACCCCATTG -3&#8217; e <italic>CMKLRI</italic> (GenBank:NM-008153.3): 5&#8217;- GTACGACGCTTACAACGACT -3&#8217; e 5&#8217;- GCACACCAAGCTGTAGATCA -3&#8217;, <italic>GAPDH</italic> (GenBank:NM-001034055): 5&#8217;- CTCATCTACCTCTCCATCGTCTG -3&#8217; e 5&#8217;- CCTGCTCTTGTCTGCCGGTGCTTG -3&#8217;. O protocolo de PCR utilizado consistiu em uma desnatura&#231;&#227;o de 5 min a 94&#176;C, seguida por 45 ciclos de 94<sup>o</sup>C por 15 s, 60<sup>o</sup>C por 30 s. Duas rea&#231;&#245;es separadas sem cDNA ou com RNA foram realizadas em paralelo como controles. A quantifica&#231;&#227;o relativa foi realizada de acordo com o m&#233;todo comparativo 2<sup>-</sup> utilizando o software Lightcycler 96<sup>&#174;</sup>. A valida&#231;&#227;o do ensaio para verificar se os primers para quemerina e CMKLRI e GAPDH apresentavam efici&#234;ncias de amplifica&#231;&#227;o semelhantes foi realizada conforme descrito anteriormente. Todas as an&#225;lises por qPCR foram realizadas de acordo com a diretriz <italic>The Minimum Information for Publication of Quantitative Real-Time PCR Experiments</italic> (MIQE).<sup><xref ref-type="bibr" rid="B21">21</xref></sup></p>
      </sec>
      <sec>
        <title>Determina&#231;&#227;o da prote&#237;na quemerina tecidual</title>
        <p>Os tecidos card&#237;acos e adiposos foram homogeneizados em 500 &#956;L de tamp&#227;o de lise RIPA (NaCl; 150 mM, SDS 0,1%, Tris; 25 mM, pH 7,4, NaF; 1 mM, fluoreto de fenilmetilsulfonila 1 mM) com um homogeneizador (Heidolph, Schwabach, Alemanha). O homogenato foi centrifugado a 10.000 &#215; RPM por 15 min a 4&#176;C (Centr&#237;fuga 5415 R; Eppendorf AG, Hamburgo, Alemanha). O sobrenadante foi recolhido e armazenado a -70&#176;C para an&#225;lise subsequente. A concentra&#231;&#227;o de prote&#237;na do sobrenadante foi estimada com o m&#233;todo de Bradford. A concentra&#231;&#227;o de quemerina foi determinada utilizando os kits ELISA espec&#237;ficos para a esp&#233;cie (EastBiopharm, China) e expressa como ng/mg de prote&#237;na tecidual.</p>
      </sec>
      <sec>
        <title>An&#225;lises estat&#237;sticas</title>
        <p>A an&#225;lise estat&#237;stica foi realizada com o software SPSS 22 (SPSS Inc., Chicago, IL, EUA). Todos os dados foram apresentados como m&#233;dia &#177; desvio padr&#227;o (DP). Os testes de Shapiro-Wilk ou Levene foram utilizados para determinar a normalidade dos dados ou igualdade das vari&#226;ncias dos erros. Todos os par&#226;metros foram analisados estatisticamente por an&#225;lise de vari&#226;ncia (ANOVA) de tr&#234;s vias com tempos de amostragem, tratamento com LC e condi&#231;&#227;o diab&#233;tica como fatores. Quando a intera&#231;&#227;o e/ou os efeitos principais eram significativos, as m&#233;dias eram comparadas entre os diferentes grupos experimentais em diferentes momentos utilizando o teste <italic>post hoc</italic> de compara&#231;&#227;o m&#250;ltipla de Tukey. Os gr&#225;ficos foram desenhados utilizando o software Graphpad Prism 8 (GraphPad Software Inc., San Diego, CA, EUA). N&#227;o utilizamos m&#233;todos estat&#237;sticos para predeterminar o tamanho da amostra. Os tamanhos das amostras foram estimados com base na disponibilidade da amostra, quest&#245;es &#233;ticas sobre a realiza&#231;&#227;o de objetivos experimentais sem desperdi&#231;ar muitos animais e estudos experimentais anteriores.<sup><xref ref-type="bibr" rid="B11">11</xref> , <xref ref-type="bibr" rid="B16">16</xref></sup> Um valor de p &lt; 0,05 foi considerado estatisticamente significante.</p>
      </sec>
    </sec>
    <sec sec-type="results">
      <title>Resultados</title>
      <p>Nossos resultados mostraram que o consumo por 5 semanas de uma dieta hipercal&#243;rica concomitante &#224; inje&#231;&#227;o de baixa dose de STZ induziu um fen&#243;tipo de DM2 caracterizado por hiperinsulinemia e hiperglicemia. O efeito dos fatores principais (condi&#231;&#227;o diab&#233;tica; 2 n&#237;veis, tratamento com LC; 2 n&#237;veis e tempo de amostragem; 3 n&#237;veis) e sua intera&#231;&#227;o em cada vari&#225;vel s&#227;o mostrados na <xref ref-type="table" rid="t1">tabela 1</xref> . Uma an&#225;lise ANOVA de tr&#234;s vias indicou um efeito principal do tempo de amostragem (p = 0,0031), tratamento com LC (p = 0,0001), condi&#231;&#227;o diab&#233;tica (p = 0,0001) e intera&#231;&#227;o do tempo de amostragem &#215; tratamento LC &#215; condi&#231;&#227;o diab&#233;tica (p = 0,0018) no n&#237;vel de insulina em diferentes grupos experimentais ( <xref ref-type="table" rid="t1">Tabela 1</xref> ). As altera&#231;&#245;es nos n&#237;veis de insulina no soro em camundongos diab&#233;ticos tratados com LC s&#227;o mostradas na <xref ref-type="fig" rid="f01">Figura 1A</xref> . O n&#237;vel s&#233;rico de insulina aumentou significativamente no dia 7 ap&#243;s a indu&#231;&#227;o do diabetes (dia 0 do tratamento com LC) em rela&#231;&#227;o aos animais controle saud&#225;veis e permaneceu elevado at&#233; o dia 28 do experimento (p&lt;0,05). O n&#237;vel s&#233;rico de insulina diminuiu de forma significante em camundongos diab&#233;ticos ap&#243;s duas e quatro semanas de tratamento com LC em compara&#231;&#227;o com camundongos diab&#233;ticos n&#227;o tratados (p &lt;0,05) ( <xref ref-type="fig" rid="f01">Figura 1A</xref> ). O tratamento de camundongos diab&#233;ticos com LC por mais tempo, entre 14 e 28 dias de tratamento, n&#227;o foi mais eficaz na redu&#231;&#227;o do n&#237;vel de insulina (p&gt;0,05) ( <xref ref-type="fig" rid="f01">Figura 1A</xref> ).</p>
      <p>
        <table-wrap id="t1">
          <label>Tabela 1</label>
          <caption>
            <title>&#8211; Resultados da an&#225;lise de ANOVA de tr&#234;s vias para determina&#231;&#227;o dos efeitos da condi&#231;&#227;o diab&#233;tica (D), tempo de amostragem (TA) e tratamento com LC (LC) e suas intera&#231;&#245;es (D &#215; TA &#215; LC) em cada vari&#225;vel</title>
          </caption>
          <table frame="hsides" rules="groups">
            <colgroup>
              <col/>
              <col/>
              <col/>
              <col/>
              <col/>
              <col/>
              <col/>
              <col/>
              <col/>
            </colgroup>
            <thead>
              <tr>
                <th align="left" rowspan="5">Vari&#225;vel</th>
                <th colspan="6">Fatores principais</th>
                <th colspan="2">Intera&#231;&#245;es dos fatores principais</th>
              </tr>
              <tr>
                <th colspan="8" rowspan="1">
                  <hr/>
                </th>
              </tr>
              <tr>
                <th colspan="2">Condi&#231;&#227;o diab&#233;tica (D)</th>
                <th colspan="2">Tratamento com LC</th>
                <th colspan="2">Tempos de amostragem (TA)</th>
                <th colspan="2">D&#215;LC&#215;TA</th>
              </tr>
              <tr>
                <th colspan="8" rowspan="1">
                  <hr/>
                </th>
              </tr>
              <tr>
                <th>p value</th>
                <th>F (1,48)</th>
                <th>p value</th>
                <th>F (1,48)</th>
                <th>p value</th>
                <th>F (2,48)</th>
                <th>p value</th>
                <th>F (2,48)</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td>Insulina</td>
                <td align="center">p = 0,0001</td>
                <td align="center">305,92</td>
                <td align="center">p = 0,0001</td>
                <td align="center">17,41</td>
                <td align="center">p = 0,0031</td>
                <td align="center">4,89</td>
                <td align="center">p = 0,0018</td>
                <td align="center">3,73</td>
              </tr>
              <tr>
                <td>Glicose</td>
                <td align="center">p = 0,0002</td>
                <td align="center">6182,2</td>
                <td align="center">p = 0,0005</td>
                <td align="center">1248,2</td>
                <td align="center">p = 0,0002</td>
                <td align="center">634,6</td>
                <td align="center">p = 0,0002</td>
                <td align="center">67,59</td>
              </tr>
              <tr>
                <td>HOMA-IR</td>
                <td align="center">p = 0,0005</td>
                <td align="center">447,02</td>
                <td align="center">p = 0,0017</td>
                <td align="center">12,95</td>
                <td align="center">p = 0,0019</td>
                <td align="center">8,12</td>
                <td align="center">p = 0,0015</td>
                <td align="center">8,91</td>
              </tr>
              <tr>
                <td>MRNA da quemerina adiposa</td>
                <td align="center">p = 0,0003</td>
                <td align="center">1761,2</td>
                <td align="center">p = 0,0003</td>
                <td align="center">1040,3</td>
                <td align="center">p = 0,0008</td>
                <td align="center">125,45</td>
                <td align="center">p = 0,0007</td>
                <td align="center">319,21</td>
              </tr>
              <tr>
                <td>MRNA da quemerina card&#237;aca</td>
                <td align="center">p = 0,0002</td>
                <td align="center">5546,3</td>
                <td align="center">p = 0,0001</td>
                <td align="center">187,6</td>
                <td align="center">p = 0,0002</td>
                <td align="center">73,36</td>
                <td align="center">p = 0,0002</td>
                <td align="center">67,9</td>
              </tr>
              <tr>
                <td>Prote&#237;na quemerina adiposa</td>
                <td align="center">p = 0,0002</td>
                <td align="center">2267,2</td>
                <td align="center">p = 0,0002</td>
                <td align="center">762,21</td>
                <td align="center">p = 0,0002</td>
                <td align="center">70,23</td>
                <td align="center">p = 0,0003</td>
                <td align="center">64,22</td>
              </tr>
              <tr>
                <td>Prote&#237;na quemerina card&#237;aca</td>
                <td align="center">p = 0,0003</td>
                <td align="center">1651,4</td>
                <td align="center">p = 0,0002</td>
                <td align="center">641,22</td>
                <td align="center">p = 0,0003</td>
                <td align="center">62,27</td>
                <td align="center">p = 0,0004</td>
                <td align="center">64,12</td>
              </tr>
              <tr>
                <td>MRNA do CMKLR1 adiposo</td>
                <td align="center">p = 0,0001</td>
                <td align="center">8376,2</td>
                <td align="center">p = 0,0001</td>
                <td align="center">306,99</td>
                <td align="center">p = 0,0001</td>
                <td align="center">96,51</td>
                <td align="center">p = 0,0001</td>
                <td align="center">65,73</td>
              </tr>
              <tr>
                <td>MRNA do CMKLR1 card&#237;aco</td>
                <td align="center">p = 0,0001</td>
                <td align="center">2172,3</td>
                <td align="center">p = 0,0002</td>
                <td align="center">65,04</td>
                <td align="center">p = 0,0003</td>
                <td align="center">75,59</td>
                <td align="center">p = 0,0002</td>
                <td align="center">7,37</td>
              </tr>
              <tr>
                <td>Quemerina s&#233;rica</td>
                <td align="center">p = 0,0003</td>
                <td align="center">3759,4</td>
                <td align="center">p = 0,0005</td>
                <td align="center">183,59</td>
                <td align="center">p = 0,0003</td>
                <td align="center">423,2</td>
                <td align="center">p = 0,0003</td>
                <td align="center">91,87</td>
              </tr>
              <tr>
                <td>IL1-&#946;</td>
                <td align="center">p = 0,0005</td>
                <td align="center">2042,1</td>
                <td align="center">p = 0,0002</td>
                <td align="center">53,12</td>
                <td align="center">p = 0,0004</td>
                <td align="center">375,6</td>
                <td align="center">p = 0,0008</td>
                <td align="center">68,46</td>
              </tr>
              <tr>
                <td>TNF-&#945;</td>
                <td align="center">p = 0,0001</td>
                <td align="center">4644,3</td>
                <td align="center">p = 0,0002</td>
                <td align="center">475,6</td>
                <td align="center">p = 0,0002</td>
                <td align="center">2516,2</td>
                <td align="center">p = 0,0002</td>
                <td align="center">439,17</td>
              </tr>
            </tbody>
          </table>
        </table-wrap>
      </p>
      <p>
        <fig id="f01">
          <label>Figura 1</label>
          <caption>
            <title>&#8211; <italic>N&#237;veis s&#233;ricos de insulina (A), glicose (B) e &#237;ndice HOMA-IR em diferentes grupos experimentais nos dias 0, 14 e 28 ap&#243;s o tratamento com LC. Os dados s&#227;o m&#233;dias &#177; DP. O n&#237;vel de signific&#226;ncia entre os grupos em cada momento de amostragem foi estabelecido em *p&lt;0,05, **p&lt;0,01, ***p&lt;0,001, ****p&lt;0,0001.</italic></title>
          </caption>
          <graphic xlink:href="1678-4170-abc-117-04-0715-00044-gf01.tif"/></fig>
      </p>
      <p>Uma an&#225;lise ANOVA de tr&#234;s vias indicou um efeito principal do tempo de amostragem (p = 0,0002), tratamento com LC (p = 0,0005), condi&#231;&#227;o diab&#233;tica (p = 0,0002) e intera&#231;&#227;o do tempo de amostragem &#215; tratamento com LC &#215; condi&#231;&#227;o diab&#233;tica (p = 0,0002) na concentra&#231;&#227;o de glicose s&#233;rica em diferentes grupos experimentais. O n&#237;vel de glicose s&#233;rica foi significativamente maior em camundongos diab&#233;ticos nos dias 14 e 28 ap&#243;s a indu&#231;&#227;o do diabetes em compara&#231;&#227;o com animais saud&#225;veis (p&lt;0,05), enquanto a administra&#231;&#227;o de dieta suplementada com HF/HC e inje&#231;&#227;o de STZ n&#227;o apresentou efeito significativo no n&#237;vel de glicose s&#233;rica durante a primeira semana de indu&#231;&#227;o experimental do diabetes (p&gt;0,05) ( <xref ref-type="fig" rid="f01">Figura 1B</xref> ). Observou-se que o tratamento de camundongos diab&#233;ticos com LC resultou em redu&#231;&#227;o significativa do a&#231;&#250;car no sangue, conforme observado nos dias 14 e 28, em compara&#231;&#227;o com camundongos diab&#233;ticos n&#227;o tratados (p &lt;0,05) ( <xref ref-type="fig" rid="f01">Figura 1B</xref> ). A ingest&#227;o de LC n&#227;o teve um efeito evidente no n&#237;vel de glicose s&#233;rica em camundongos saud&#225;veis (p&gt;0,05) ( <xref ref-type="fig" rid="f01">Figura 1B</xref> ).</p>
      <p>Uma an&#225;lise ANOVA de tr&#234;s vias indicou um efeito principal do tempo de amostragem (p = 0,0019), tratamento com LC (p = 0,0017), condi&#231;&#227;o diab&#233;tica (p = 0,0005) e intera&#231;&#227;o do tempo de amostragem &#215; tratamento LC &#215; condi&#231;&#227;o diab&#233;tica (p = 0,0015) no &#237;ndice HOMA-IR em diferentes grupos experimentais. O &#237;ndice HOMA-IR em animais diab&#233;ticos aumentou significativamente no 14&#186; e 28&#186; dias do per&#237;odo experimental em rela&#231;&#227;o aos camundongos saud&#225;veis (p&lt;0,05), enquanto n&#227;o apresentou altera&#231;&#227;o significativa na primeira semana ap&#243;s a indu&#231;&#227;o experimental do diabetes (p &gt;0,05) ( <xref ref-type="fig" rid="f01">Figura 1C</xref> ). A administra&#231;&#227;o oral de LC teve efeito de redu&#231;&#227;o significativa no &#237;ndice HOMA-IR nos dias 14 e 28 do per&#237;odo experimental em camundongos diab&#233;ticos (p &lt;0,05) ( <xref ref-type="fig" rid="f01">Figura 1C</xref> ). Como mostrado na <xref ref-type="fig" rid="f02">Figura 2</xref> , foi observado maior peso corporal em camundongos que receberam dieta suplementada com HF/HC em todos os momentos do experimento em compara&#231;&#227;o com camundongos saud&#225;veis (p&lt;0,05). Durante as quatro semanas de observa&#231;&#227;o dos camundongos diab&#233;ticos tratados com LC, houve uma perda de peso, em rela&#231;&#227;o ao dia 0, ou seja, antes do in&#237;cio do tratamento (p &lt;0,05) ( <xref ref-type="fig" rid="f02">Figura 2</xref> ).</p>
      <p>
        <fig id="f02">
          <label>Figura 2</label>
          <caption>
            <title>&#8211; <italic>Mudan&#231;as no peso corporal em diferentes grupos experimentais nos dias 0, 14 e 28 ap&#243;s o tratamento com LC. Os dados s&#227;o m&#233;dias &#177; DP. O n&#237;vel de signific&#226;ncia entre os grupos em cada momento de amostragem foi estabelecido em *p &lt;0,05, **p &lt;0,01, ***p &lt;0,001, ****p &lt;0,0001.</italic></title>
          </caption>
          <graphic xlink:href="1678-4170-abc-117-04-0715-00044-gf02.tif"/></fig>
      </p>
      <p>Em rela&#231;&#227;o &#224; concentra&#231;&#227;o de quemerina s&#233;rica, uma ANOVA de tr&#234;s vias mostrou um efeito principal do tempo de amostragem (p = 0,0003), tratamento com LC (p = 0,0005), condi&#231;&#227;o diab&#233;tica (p = 0,0003) e intera&#231;&#227;o do tempo de amostragem &#215; tratamento LC &#215; condi&#231;&#227;o diab&#233;tica (p = 0,0003). Nossos resultados mostraram que os n&#237;veis s&#233;ricos de quemerina foram significativamente maiores no grupo diab&#233;tico do que no grupo controle em todos os momentos de amostragem, com o n&#237;vel mais alto no dia 28 do experimento (p&lt;0,05). Duas semanas ap&#243;s o tratamento com LC, o n&#237;vel de quemerina s&#233;rica de camundongos diab&#233;ticos n&#227;o mostrou diferen&#231;a significante com o de camundongos diab&#233;ticos n&#227;o tratados (p&gt;0,05), enquanto um efeito de redu&#231;&#227;o significante no n&#237;vel de quemerina s&#233;rica foi observado quando camundongos diab&#233;ticos consumiram LC por 28 dias (p&lt; 0,05) ( <xref ref-type="fig" rid="f03">Figura 3</xref> ).</p>
      <p>
        <fig id="f03">
          <label>Figura 3</label>
          <caption>
            <title>&#8211; <italic>N&#237;veis s&#233;ricos de quemerina em diferentes grupos experimentais nos dias 0, 14 e 28 ap&#243;s o tratamento com LC. Os dados s&#227;o m&#233;dias &#177; DP. O n&#237;vel de signific&#226;ncia entre os grupos em cada momento de amostragem foi estabelecido em *p&lt;0,05, **p&lt;0,01, ***p &lt;0,001, ****p &lt;0,0001.</italic></title>
          </caption>
          <graphic xlink:href="1678-4170-abc-117-04-0715-00044-gf03.tif"/></fig>
      </p>
      <p>Em rela&#231;&#227;o aos n&#237;veis de quemerina do m&#250;sculo card&#237;aco e de mRNA do CMKLR1, uma ANOVA de tr&#234;s vias mostrou um efeito principal do tempo de amostragem (quemerina p = 0,0001, CMKLR1 p = 0,0003), tratamento com LC (quemerina, p = 0,0002; CMKLR1, p = 0,0002), condi&#231;&#227;o diab&#233;tica (quemerina, p = 0,0002; CMKLR1, p = 0,0001) e intera&#231;&#227;o entre tr&#234;s fatores (quemerina, p&lt;0,0001; CMKLR1, p = 0,0002). Os n&#237;veis de mRNA e prote&#237;na da quemerina e CMKLRI no tecido card&#237;aco de camundongos diab&#233;ticos foram maiores do que os dos animais saud&#225;veis em todos os momentos de amostragem ap&#243;s a indu&#231;&#227;o do diabetes (p &lt;0,05) ( <xref ref-type="fig" rid="f04">Figura 4</xref> e <xref ref-type="table" rid="t2">Tabela 2</xref> ). O consumo oral de LC por duas semanas n&#227;o teve efeito significativo na redu&#231;&#227;o da express&#227;o da quemerina ou CMKLRI no tecido card&#237;aco de camundongos diab&#233;ticos (p&gt;0,05), enquanto 28 dias ap&#243;s o tratamento com LC a express&#227;o dos genes estudados foi reduzida no tecido card&#237;aco de camundongos diab&#233;ticos em compara&#231;&#227;o com os animais diab&#233;ticos n&#227;o tratados (p&lt;0,05) ( <xref ref-type="fig" rid="f04">Figura 4</xref> , <xref ref-type="table" rid="t2">Tabela 2</xref> ).</p>
      <p>
        <fig id="f04">
          <label>Figura 4</label>
          <caption>
            <title>&#8211; <italic>N&#237;veis de express&#227;o g&#234;nica de quemerina (A) e CMKLRI (B) no tecido adiposo de diferentes grupos experimentais nos dias 0, 14 e 28 ap&#243;s o tratamento com LC. O m&#233;todo qRT-PCR foi utilizado para an&#225;lise da express&#227;o relativa dos genes estudados. GAPDH foi utilizado como gene de housekeeping. O n&#237;vel de signific&#226;ncia entre os grupos em cada momento de amostragem foi estabelecido em *p&lt;0,05, **p&lt;0,01, ***p&lt;0,001, ****p&lt;0,0001.</italic></title>
          </caption>
          <graphic xlink:href="1678-4170-abc-117-04-0715-00044-gf04.tif"/></fig>
      </p>
      <p>
        <table-wrap id="t2">
          <label>Tabela 2</label>
          <caption>
            <title>&#8211; N&#237;vel de quemerina no tecido card&#237;aco dos grupos experimentais. Os dados s&#227;o apresentados como m&#233;dia &#177; DP. Letras min&#250;sculas diferentes (a, b) demonstram diferen&#231;as significativas entre os grupos em cada dia do experimento (p&lt;0,05). Letras mai&#250;sculas diferentes (A, B) demonstram diferen&#231;as significativas entre os tempos de tratamento em cada grupo (p &lt;0,05)</title>
          </caption>
          <table frame="hsides" rules="groups">
            <colgroup>
              <col/>
              <col/>
              <col/>
              <col/>
            </colgroup>
            <thead>
              <tr>
                <th colspan="4">N&#237;vel de quemerina no tecido card&#237;aco (ng/mg prote&#237;na)</th>
              </tr>
              <tr>
                <th colspan="4">
                  <hr/>
                </th>
              </tr>
              <tr>
                <th colspan="4">Dia ap&#243;s o tratamento com LC</th>
              </tr>
              <tr>
                <th colspan="4">
                  <hr/>
                </th>
              </tr>
              <tr>
                <th align="left" style="font-weight:normal"> </th>
                <th>0</th>
                <th>14</th>
                <th>28</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td>Controle</td>
                <td align="center">2,47 &#177; 0,42<sup>aA</sup></td>
                <td align="center">2,56 &#177; 0,27<sup>aA</sup></td>
                <td align="center">2,27 &#177; 0,22<sup>aA</sup></td>
              </tr>
              <tr>
                <td>Diab&#233;tico</td>
                <td align="center">3,01 &#177; 0,31<sup>aA</sup></td>
                <td align="center">4,97 &#177; 0,48<sup>bB</sup></td>
                <td align="center">5,51 &#177; 0,41<sup>bB</sup></td>
              </tr>
              <tr>
                <td>Diab&#233;tico + LC</td>
                <td align="center">2,81 &#177; 0,16<sup>aA</sup></td>
                <td align="center">4,42 &#177; 0,38<sup>bB</sup></td>
                <td align="center">3,13 &#177; 0,29<sup>cA</sup></td>
              </tr>
              <tr>
                <td>Controle + LC</td>
                <td align="center">2,32 &#177; 0,38<sup>aA</sup></td>
                <td align="center">2,67 &#177; 0,33<sup>aA</sup></td>
                <td align="center">2,37 &#177; 0,28<sup>aA</sup></td>
              </tr>
            </tbody>
          </table>
          <table-wrap-foot>
            <fn id="TFN1">
              <p>
                <italic>LC: l-carnitina.</italic>
              </p>
            </fn>
          </table-wrap-foot>
        </table-wrap>
      </p>
      <p>Em rela&#231;&#227;o &#224; quemerina adiposa e n&#237;veis de mRNA e prote&#237;na de CMKLR1, uma ANOVA de tr&#234;s vias mostrou um efeito principal do tempo de amostragem (quemerina, p = 0,0008; CMKLR1 p = 0,0001), tratamento com LC (quemerina, p = 0,0003; CMKLR1, p = 0,0001), condi&#231;&#227;o diab&#233;tica (quemerina, p = 0,0003; CMKLR1 p = 0,0001) e intera&#231;&#227;o entre os tr&#234;s fatores (quemerina, p = 0,0007; CMKLR1, p = 0,0001). Observou-se que os animais que receberam dieta suplementada com HF/HC apresentaram n&#237;veis maiores de prote&#237;na e de mRNA de quemerina e CMKLRI no tecido adiposo no 7&#186;, 14&#186; e 28&#186; dias ap&#243;s a alimenta&#231;&#227;o final em compara&#231;&#227;o com os animais que receberam dieta normal (p &lt;0,05) ( <xref ref-type="fig" rid="f05">Figura 5 A-B</xref> , <xref ref-type="table" rid="t3">Tabela 3</xref> ). O tratamento de camundongos diab&#233;ticos com LC por 14 ou 28 dias resultou em uma redu&#231;&#227;o significativa dos n&#237;veis de prote&#237;na quemerina e mRNA no tecido adiposo de animais diab&#233;ticos quando comparados com camundongos diab&#233;ticos n&#227;o tratados (p&lt;0,05) ( <xref ref-type="fig" rid="f05">Figura 5A</xref> , <xref ref-type="table" rid="t2">Tabela 2</xref> ). Os animais que receberam LC por 14 dias n&#227;o apresentaram altera&#231;&#227;o significativa na express&#227;o de CMKLRI (p &gt;0,05), enquanto aqueles que foram tratados com LC por 28 dias apresentaram menor express&#227;o de CMKLRI quando comparados com camundongos diab&#233;ticos n&#227;o tratados (p&lt;0,05) ( <xref ref-type="fig" rid="f05">Figura 5B</xref> ).</p>
      <p>
        <fig id="f05">
          <label>Figura 5</label>
          <caption>
            <title>&#8211; <italic>N&#237;veis de express&#227;o g&#234;nica de quemerina (A) e CMKLRI (B) no tecido card&#237;aco de diferentes grupos experimentais nos dias 0, 14 e 28 ap&#243;s o tratamento com LC. O m&#233;todo qRT-PCR foi utilizado para an&#225;lise da express&#227;o relativa dos genes estudados. GAPDH foi utilizado como gene de housekeeping. Os dados s&#227;o m&#233;dias &#177; DP. O n&#237;vel de signific&#226;ncia entre os grupos em cada momento de amostragem foi estabelecido em *p&lt;0,05, **p&lt;0,01, ***p&lt;0,001, ****p&lt;0,0001.</italic></title>
          </caption>
          <graphic xlink:href="1678-4170-abc-117-04-0715-00044-gf05.tif"/></fig>
      </p>
      <p>
        <table-wrap id="t3">
          <label>Tabela 3</label>
          <caption>
            <title>&#8211; N&#237;vel de quemerina no tecido adiposo de diferentes grupos experimentais. Os dados s&#227;o apresentados como m&#233;dia &#177; DP. Letras min&#250;sculas diferentes (a, b) demonstram diferen&#231;as significativas entre os grupos em cada dia do experimento (p&lt;0,05). Letras mai&#250;sculas diferentes (A, B) demonstram diferen&#231;as significativas entre os tempos de tratamento em cada grupo (p &lt;0,05)</title>
          </caption>
          <table frame="hsides" rules="groups">
            <colgroup>
              <col/>
              <col/>
              <col/>
              <col/>
            </colgroup>
            <thead>
              <tr>
                <th colspan="4">N&#237;vel de quemerina no tecido adiposo (ng/mg prote&#237;na)</th>
              </tr>
              <tr>
                <th colspan="4">
                  <hr/>
                </th>
              </tr>
              <tr>
                <th colspan="4">Dia ap&#243;s o tratamento com LC</th>
              </tr>
              <tr>
                <th colspan="4">
                  <hr/>
                </th>
              </tr>
              <tr>
                <th align="left" style="font-weight:normal"> </th>
                <th>0</th>
                <th>14</th>
                <th>28</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td>Controle</td>
                <td align="center">7,62 &#177; 2,58<sup>aA</sup></td>
                <td align="center">8,11 &#177; 1,32<sup>aA</sup></td>
                <td align="center">6,49 &#177; 1,07<sup>aA</sup></td>
              </tr>
              <tr>
                <td>Diab&#233;tico</td>
                <td align="center">13,22 &#177; 3,61<sup>bA</sup></td>
                <td align="center">14,78 &#177; 2,59<sup>bA</sup></td>
                <td align="center">16,72 &#177; 97<sup>bB</sup></td>
              </tr>
              <tr>
                <td>Diab&#233;tico + LC</td>
                <td align="center">12,64 &#177; 2,09<sup>bA</sup></td>
                <td align="center">10,36 &#177; 1,78<sup>cB</sup></td>
                <td align="center">10,97 &#177; 3,12<sup>bB</sup></td>
              </tr>
              <tr>
                <td>Controle + LC</td>
                <td align="center">6,82 &#177; 1,94<sup>aA</sup></td>
                <td align="center">7,09 &#177; 2,06<sup>aA</sup></td>
                <td align="center">7,44 &#177; 1,19<sup>aA</sup></td>
              </tr>
            </tbody>
          </table>
          <table-wrap-foot>
            <fn id="TFN2">
              <p>
                <italic>LC: l-carnitina.</italic>
              </p>
            </fn>
          </table-wrap-foot>
        </table-wrap>
      </p>
      <p>Em rela&#231;&#227;o &#224; concentra&#231;&#227;o s&#233;rica de IL1-&#946; e TNF-&#945;, uma ANOVA de tr&#234;s vias mostrou um efeito principal do tempo de amostragem (IL1-&#946;, p = 0,0004 e TNF-&#945;, p = 0,0002), tratamento (IL1-&#946;, p = 0,0002 e TNF-&#945;, p = 0,0002), condi&#231;&#227;o diab&#233;tica (IL1-&#946;; p = 0,0005, TNF-&#945; p = 0,0001) e intera&#231;&#227;o entre tr&#234;s fatores (IL1-&#946;, p = 0,0008; TNF-&#945;, p = 0,0002). Os n&#237;veis s&#233;ricos de IL1-&#946; e TNF-&#945; aumentaram significativamente no grupo diab&#233;tico em compara&#231;&#227;o com o grupo controle nos dias 14 e 28 ap&#243;s a indu&#231;&#227;o do diabetes (p&lt;0,05) ( <xref ref-type="table" rid="t4">Tabelas 4</xref> e <xref ref-type="table" rid="t5">5</xref> ). O tratamento de camundongos diab&#233;ticos com LC por 14 dias n&#227;o teve efeitos significativos nos n&#237;veis s&#233;ricos de IL-1&#946; e TNF-&#945; em compara&#231;&#227;o com camundongos diab&#233;ticos n&#227;o tratados (p&gt;0,05). No entanto, quatro semanas ap&#243;s o tratamento com LC, as concentra&#231;&#245;es s&#233;ricas de ambos os fatores inflamat&#243;rios foram significativamente reduzidas em compara&#231;&#227;o com camundongos diab&#233;ticos n&#227;o tratados.</p>
      <p>
        <table-wrap id="t4">
          <label>Tabela 4</label>
          <caption>
            <title>&#8211; N&#237;vel s&#233;rico de IL1-&#946; em diferentes grupos experimentais. Os dados s&#227;o apresentados como m&#233;dia &#177; DP. Letras min&#250;sculas diferentes (a, b) demonstram diferen&#231;as significativas entre os grupos em cada dia do experimento (p&lt;0,05). Letras mai&#250;sculas diferentes (A, B) demonstram diferen&#231;as significativas entre os tempos de tratamento em cada grupo (p&lt;0,05). LC: l-carnitina</title>
          </caption>
          <table frame="hsides" rules="groups">
            <colgroup>
              <col/>
              <col/>
              <col/>
              <col/>
            </colgroup>
            <thead>
              <tr>
                <th colspan="4">N&#237;vel s&#233;rico de TNF-&#945; (pmol/L)</th>
              </tr>
              <tr>
                <th colspan="4">
                  <hr/>
                </th>
              </tr>
              <tr>
                <th colspan="4">Dia ap&#243;s o tratamento com LC</th>
              </tr>
              <tr>
                <th colspan="4">
                  <hr/>
                </th>
              </tr>
              <tr>
                <th align="left" style="font-weight:normal"> </th>
                <th>0</th>
                <th>14</th>
                <th>28</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td>Controle</td>
                <td align="center">0,71 &#177; 0,19<sup>aA</sup></td>
                <td align="center">0,65 &#177; 0,10<sup>aA</sup></td>
                <td align="center">0,75 &#177; 0,09<sup>aA</sup></td>
              </tr>
              <tr>
                <td>Diab&#233;tico</td>
                <td align="center">0,65 &#177; 0,11<sup>aA</sup></td>
                <td align="center">3,92 &#177; 0,38<sup>bB</sup></td>
                <td align="center">7,10 &#177; 0,68<sup>bC</sup></td>
              </tr>
              <tr>
                <td>Diab&#233;tico + LC</td>
                <td align="center">1,33 &#177; 0,16<sup>bA</sup></td>
                <td align="center">3,34 &#177; 0,50<sup>bB</sup></td>
                <td align="center">3,94 &#177; 0,43<sup>cB</sup></td>
              </tr>
              <tr>
                <td>Controle + LC</td>
                <td align="center">0,78 &#177; 0,18<sup>aA</sup></td>
                <td align="center">0,98 &#177; 0,16<sup>aA</sup></td>
                <td align="center">0,57 &#177; 0,11<sup>dB</sup></td>
              </tr>
            </tbody>
          </table>
          <table-wrap-foot>
            <fn id="TFN3">
              <p>
                <italic>LC: l-carnitina.</italic>
              </p>
            </fn>
          </table-wrap-foot>
        </table-wrap>
      </p>
      <p>
        <table-wrap id="t5">
          <label>Tabela 5</label>
          <caption>
            <title>&#8211; N&#237;vel s&#233;rico de TNF-&#945; em diferentes grupos experimentais nos dias 0, 14 e 28 ap&#243;s o tratamento com LC. Os dados s&#227;o apresentados como m&#233;dia &#177; DP. Letras min&#250;sculas diferentes (a, b) demonstram diferen&#231;as significativas entre os grupos em cada dia do experimento (p&lt;0,05). Letras mai&#250;sculas diferentes (A, B) demonstram diferen&#231;as significativas entre os tempos de tratamento em cada grupo (p&lt;0,05)</title>
          </caption>
          <table frame="hsides" rules="groups">
            <colgroup>
              <col/>
              <col/>
              <col/>
              <col/>
            </colgroup>
            <thead>
              <tr>
                <th colspan="4">N&#237;vel s&#233;rico de IL1-&#946; (pmol/L)</th>
              </tr>
              <tr>
                <th colspan="4">
                  <hr/>
                </th>
              </tr>
              <tr>
                <th colspan="4">Dia ap&#243;s o tratamento com LC</th>
              </tr>
              <tr>
                <th colspan="4">
                  <hr/>
                </th>
              </tr>
              <tr>
                <th align="left" style="font-weight:normal"> </th>
                <th>0</th>
                <th>14</th>
                <th>28</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td>Controle</td>
                <td align="center">0,93 &#177; 0,11<sup>aA</sup></td>
                <td align="center">1,02 &#177; 0,14<sup>aA</sup></td>
                <td align="center">0,89 &#177; 0,31<sup>aA</sup></td>
              </tr>
              <tr>
                <td>Diab&#233;tico</td>
                <td align="center">1,23 &#177; 0,33<sup>aA</sup></td>
                <td align="center">2,96 &#177; 0,12<sup>bB</sup></td>
                <td align="center">5,78 &#177; 0,21<sup>bB</sup></td>
              </tr>
              <tr>
                <td>Diab&#233;tico + LC</td>
                <td align="center">1,33 &#177; 0,26<sup>aA</sup></td>
                <td align="center">2,23 &#177; 0,27<sup>bB</sup></td>
                <td align="center">3,46 &#177; 0,12<sup>cC</sup></td>
              </tr>
              <tr>
                <td>Controle + LC</td>
                <td align="center">1,07 &#177; 0,24<sup>aA</sup></td>
                <td align="center">0,98 &#177; 0,19<sup>aA</sup></td>
                <td align="center">0,82 &#177; 0,41<sup>aA</sup></td>
              </tr>
            </tbody>
          </table>
          <table-wrap-foot>
            <fn id="TFN4">
              <p>
                <italic>LC: l-carnitina.</italic>
              </p>
            </fn>
          </table-wrap-foot>
        </table-wrap>
      </p>
    </sec>
    <sec sec-type="discussion">
      <title>Discuss&#227;o</title>
      <p>No presente estudo, foi estudado o efeito da suplementa&#231;&#227;o de LC na express&#227;o de quemerina e seu receptor nos tecidos adiposo e card&#237;aco de ratos obesos e resistentes &#224; insulina experimentalmente induzidos. De acordo com estudos anteriores em modelo de roedor de diabetes tipo 2, nossos resultados mostraram que o consumo de cinco semanas de dieta suplementada com HF/HC, juntamente com a inje&#231;&#227;o de uma &#250;nica dose baixa de STZ em camundongos, resultou em resist&#234;ncia &#224; insulina e obesidade, caracterizada por hiperglicemia, hiperinsulinemia e aumento do &#237;ndice HOMA-IR e peso corporal.<sup><xref ref-type="bibr" rid="B16">16</xref> , <xref ref-type="bibr" rid="B18">18</xref> , <xref ref-type="bibr" rid="B19">19</xref></sup> Foi observado que a suplementa&#231;&#227;o da dieta com HF/HC por cinco semanas resultou em hiperinsulinemia sem altera&#231;&#227;o &#243;bvia da glicose sangu&#237;nea, enquanto ap&#243;s duas semanas de alimenta&#231;&#227;o com dieta hipercal&#243;rica, os animais mostraram sintomas s&#233;ricos de resist&#234;ncia &#224; insulina, incluindo hiperinsulinemia e hiperglicemia. Esses achados sugerem que as altera&#231;&#245;es metab&#243;licas s&#233;ricas induzidas por esse tratamento foram mais semelhantes &#224;s do diabetes tipo 2 do que &#224;s do diabetes tipo 1.</p>
      <p>Nossos resultados mostraram que a express&#227;o de quemerina e seu receptor CMKLRI nos tecidos adiposo e card&#237;aco de camundongos diab&#233;ticos, aumentou ap&#243;s a indu&#231;&#227;o do diabetes experimental. Tamb&#233;m foi observado que animais diab&#233;ticos apresentaram maior concentra&#231;&#227;o s&#233;rica de quemerina em compara&#231;&#227;o com animais saud&#225;veis. Esse achado sugere que mudan&#231;as simult&#226;neas na quantidade de quemerina e seu receptor no estado diab&#233;tico exacerba a fun&#231;&#227;o desse horm&#244;nio nos tecidos-alvo e isso pode desempenhar um papel importante no desenvolvimento de dist&#250;rbios funcionais dos tecidos adiposo e card&#237;aco no estado diab&#233;tico. A maior parte dos dados humanos e de animais suporta uma liga&#231;&#227;o entre quemerina, obesidade e s&#237;ndrome metab&#243;lica, um grupo de dist&#250;rbios metab&#243;licos que aumentam o risco de DCV. De acordo com nossos resultados, estudos em humanos e animais relataram os achados paralelos de que animais obesos e diab&#233;ticos t&#234;m n&#237;veis circulantes elevados de quemerina em compara&#231;&#227;o com indiv&#237;duos ou animais saud&#225;veis ou magros.<sup><xref ref-type="bibr" rid="B22">22</xref> , <xref ref-type="bibr" rid="B23">23</xref></sup> V&#225;rios mecanismos poss&#237;veis podem ser aceitos sobre os efeitos do aumento da express&#227;o de quemerina e CMKLRI no in&#237;cio e progress&#227;o da resist&#234;ncia &#224; insulina em animais diab&#233;ticos. Sabe-se agora que a inflama&#231;&#227;o tem um papel importante na resist&#234;ncia &#224; insulina do tecido adiposo e na disfun&#231;&#227;o do m&#250;sculo card&#237;aco.<sup><xref ref-type="bibr" rid="B24">24</xref></sup> A obesidade est&#225; correlacionada a um aumento significativo na produ&#231;&#227;o de citocinas pr&#243;-inflamat&#243;rias, como IL-1&#946; e TNF-&#945;, que podem induzir resist&#234;ncia &#224; insulina e morte celular no m&#250;sculo card&#237;aco.<sup><xref ref-type="bibr" rid="B25">25</xref> , <xref ref-type="bibr" rid="B26">26</xref></sup> Nossos achados mostraram n&#237;veis s&#233;ricos aumentados de IL1-&#946; e TNF-&#945; ap&#243;s a indu&#231;&#227;o do diabetes. Os n&#237;veis s&#233;ricos de quemerina se correlacionam com os n&#237;veis de citocinas pr&#243;-inflamat&#243;rias, tais como TNF-&#945;, IL1-&#946; e IL-6.<sup><xref ref-type="bibr" rid="B6">6</xref> , <xref ref-type="bibr" rid="B7">7</xref> , <xref ref-type="bibr" rid="B25">25</xref></sup> A quemerina tamb&#233;m tem efeitos adversos sobre os cardiomi&#243;citos atrav&#233;s da indu&#231;&#227;o da caspase 9 e apoptose celular mediada por AKT.<sup><xref ref-type="bibr" rid="B10">10</xref></sup> Tomados em conjunto, esses dados permitem a conclus&#227;o de que a superexpress&#227;o observada de quemerina e seu receptor em tecidos adiposos e card&#237;acos de camundongos diab&#233;ticos pode ter um papel importante na progress&#227;o da resist&#234;ncia &#224; insulina e disfun&#231;&#245;es card&#237;acas no estado diab&#233;tico.</p>
      <p>Nossos resultados mostraram que a administra&#231;&#227;o de LC por 4 semanas pode atenuar a express&#227;o da quemerina e de seu receptor nos tecidos adiposo e card&#237;aco de camundongos diab&#233;ticos. Essas altera&#231;&#245;es foram associadas &#224; melhora dos sintomas de resist&#234;ncia &#224; insulina e &#224; redu&#231;&#227;o dos n&#237;veis s&#233;ricos de quemerina e de alguns fatores inflamat&#243;rios. Em concord&#226;ncia com os resultados do presente estudo, estudos anteriores mostraram que o uso de LC leva ao aumento da sensibilidade geral &#224; insulina e da capta&#231;&#227;o de glicose mediada pela insulina no corpo inteiro em animais ou humanos com diabetes tipo 2.<sup><xref ref-type="bibr" rid="B16">16</xref> , <xref ref-type="bibr" rid="B26">26</xref></sup> Evid&#234;ncias consider&#225;veis apoiam que o suprimento excessivo de &#225;cidos graxos e a obesidade levam ao ac&#250;mulo ect&#243;pico de v&#225;rios metab&#243;litos lip&#237;dicos no m&#250;sculo card&#237;aco e possivelmente em outros tecidos que s&#227;o prejudiciais &#224; sinaliza&#231;&#227;o da insulina, levando &#224; resist&#234;ncia insul&#237;nica.<sup><xref ref-type="bibr" rid="B27">27</xref></sup> As c&#233;lulas do m&#250;sculo card&#237;aco n&#227;o podem sintetizar LC <italic>de novo</italic> e devem obter a LC de forma ex&#243;gena atrav&#233;s da carnitina/transportador de c&#225;tions org&#226;nicos 2.<sup><xref ref-type="bibr" rid="B28">28</xref></sup> Com base nesses achados, sugerimos que a suplementa&#231;&#227;o de LC na dieta pode restaurar o <italic>pool</italic> de LC e reduzir os metab&#243;litos lip&#237;dicos e a lipotoxicidade nos tecidos card&#237;aco e adiposo.</p>
      <p>Com base em nosso conhecimento, os efeitos da LC no n&#237;vel sist&#234;mico de quemerina ou sua express&#227;o no tecido card&#237;aco de animais ou humanos com diabetes n&#227;o foram investigados at&#233; o momento. Nossos resultados, pela primeira vez, mostraram que os n&#237;veis de prote&#237;na e mRNA da quemerina e seu receptor eram reduzidos no tecido card&#237;aco de camundongos diab&#233;ticos, concomitantemente ao aumento da sensibilidade &#224; insulina em todo o corpo. Achados anteriores mostraram que os n&#237;veis de mRNA e prote&#237;na da quemerina estavam elevados no tecido adiposo epic&#225;rdico de pacientes com doen&#231;a arterial coronariana.<sup><xref ref-type="bibr" rid="B29">29</xref></sup> O n&#237;vel s&#233;rico de quemerina tamb&#233;m est&#225; elevado em pacientes com doen&#231;a arterial coronariana e correlacionado com a gravidade e extens&#227;o da estenose coronariana e v&#225;rios par&#226;metros cardiometab&#243;licos.<sup><xref ref-type="bibr" rid="B30">30</xref></sup> Foi observado que a quemerina aumenta a apoptose e a atividade da caspase 9 em cardiomi&#243;citos murinos e melhora os par&#226;metros cardioprotetores no cora&#231;&#227;o de rato perfundido isolado.<sup><xref ref-type="bibr" rid="B10">10</xref> , <xref ref-type="bibr" rid="B31">31</xref></sup> O tratamento com quemerina tamb&#233;m altera o destino das c&#233;lulas miobl&#225;sticas, da miog&#234;nese para a adipog&#234;nese, que &#233; caracterizada pelo aumento dos n&#237;veis de ERO e do conte&#250;do de TG das c&#233;lulas tratadas.<sup><xref ref-type="bibr" rid="B32">32</xref></sup> Tomados em conjunto, concluiu-se que a redu&#231;&#227;o da express&#227;o da quemerina e de seu receptor no tecido card&#237;aco de camundongos diab&#233;ticos ap&#243;s o tratamento com LC pode atenuar o efeito adverso da quemerina nos cardiomi&#243;citos em animais diab&#233;ticos. Mais estudos s&#227;o necess&#225;rios para confirmar esta opini&#227;o.</p>
      <p>Embora os resultados do presente estudo tenham mostrado que o tratamento com LC pode atenuar o aumento da express&#227;o da quemerina nos tecidos-alvo, os mecanismos moleculares que regulam sua express&#227;o permanecem pouco compreendidos. Nossos resultados mostraram que o tratamento com LC pode reduzir os n&#237;veis s&#233;ricos de TNF-&#945; e IL1-&#946; em ratos obesos diab&#233;ticos. Foi observado que essas citocinas pr&#243;-inflamat&#243;rias induzem a express&#227;o e secre&#231;&#227;o de mRNA da quemerina pelos adip&#243;citos 3T3-L1.<sup><xref ref-type="bibr" rid="B33">33</xref></sup> O n&#237;vel s&#233;rico de quemerina tamb&#233;m est&#225; associado ao n&#237;vel s&#233;rico de TNF-&#945; em pacientes obesos.<sup><xref ref-type="bibr" rid="B34">34</xref></sup> Com base nesses achados, a redu&#231;&#227;o da express&#227;o de quemerina em camundongos diab&#233;ticos pode ser devido a uma diminui&#231;&#227;o na secre&#231;&#227;o de mediadores inflamat&#243;rios. A melhora da hiperinsulinemia tamb&#233;m pode ser outro mecanismo da LC na redu&#231;&#227;o da express&#227;o da quemerina. Nossos resultados mostraram que a LC pode atenuar o aumento do n&#237;vel de insulina em camundongos obesos e diab&#233;ticos. Como a insulina pode aumentar a secre&#231;&#227;o de quemerina do tecido adiposo <italic>in vitro</italic> e em explantes de tecido,<sup><xref ref-type="bibr" rid="B35">35</xref></sup> sugerimos que a redu&#231;&#227;o da insulina em animais tratados com LC pode ter um papel regulador na express&#227;o da quemerina nos tecidos adiposo e card&#237;aco de camundongos diab&#233;ticos.</p>
      <p>Esse estudo tem algumas limita&#231;&#245;es. Em nosso estudo, a express&#227;o g&#234;nica foi medida no tecido card&#237;aco total em animais experimentais. Tendo em vista que v&#225;rios tipos de c&#233;lulas card&#237;acas, como cardiomi&#243;citos e fibroblastos card&#237;acos, podem ter diferentes a&#231;&#245;es na patog&#234;nese da doen&#231;a card&#237;aca, nossos dados n&#227;o permitiram distinguir perfis de express&#227;o entre os v&#225;rios tipos de c&#233;lulas. Al&#233;m disso, foram confirmadas diferen&#231;as nos perfis de express&#227;o g&#234;nica entre os tecidos card&#237;acos dos ventr&#237;culos direito e esquerdo e nos &#225;trios, al&#233;m das diferen&#231;as entre os tipos de c&#233;lulas card&#237;acas. Assim, n&#227;o diferenciamos a express&#227;o g&#234;nica entre diferentes partes do tecido card&#237;aco nos animais experimentais. Outra limita&#231;&#227;o est&#225; relacionada ao fato de que medimos todos os fatores em animais adultos jovens e em um modelo experimental de diabetes de curto prazo. A este respeito, &#233; interessante notar que o envelhecimento e o diabetes de longa dura&#231;&#227;o s&#227;o, de longe, o fator de risco dominante para o desenvolvimento de doen&#231;as cardiovasculares, e a preval&#234;ncia de doen&#231;as cardiovasculares aumenta dramaticamente com o aumento da idade. N&#227;o determinamos se o tratamento com LC em ratos idosos ou diabetes de longa dura&#231;&#227;o leva a uma downregula&#231;&#227;o semelhante &#224; express&#227;o de quemerina e seu receptor no tecido card&#237;aco de ratos diab&#233;ticos.</p>
    </sec>
    <sec sec-type="conclusions">
      <title>Conclus&#227;o</title>
      <p>Em resumo, nossos dados mostraram que o consumo de uma dieta hipercal&#243;rica resultou em obesidade, resist&#234;ncia &#224; insulina e upregula&#231;&#227;o da quemerina e seu receptor, CMKLRI, nos tecidos adiposo e card&#237;aco de camundongos. O tratamento de camundongos diab&#233;ticos com LC pode atenuar os sintomas de resist&#234;ncia &#224; insulina e suprimir a superexpress&#227;o de quemerina em animais diab&#233;ticos. Os resultados do presente experimento ajudam a compreender o novo efeito regulat&#243;rio da LC na express&#227;o do gene card&#237;aco em condi&#231;&#245;es de obesidade e diabetes. Mais estudos s&#227;o necess&#225;rios para fornecer mais evid&#234;ncias sobre a terapia nutricional com LC para o manejo n&#227;o farmacol&#243;gico de pacientes com diabetes e DCV com base na regula&#231;&#227;o dos componentes da quemerina no m&#250;sculo card&#237;aco.</p>
    </sec>
  </body>
  <back>
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    <fn-group>
      <fn fn-type="other">
        <p>Vincula&#231;&#227;o acad&#234;mica</p>
        <p>Este artigo &#233; parte de tese de doutorado de Rezvan Amiri pela Shahid Chamran University of Ahvaz.</p>
      </fn>
    </fn-group>
    <fn-group>
      <fn fn-type="supported-by">
        <p>Fontes de financiamento: O presente estudo foi financiado pela Shahid Chamran University of Ahvaz.</p>
      </fn>
    </fn-group>
  </back>
  <sub-article article-type="translation" id="TRen" xml:lang="en">
    <front-stub>
      <article-categories>
        <subj-group subj-group-type="heading">
          <subject>Original Article</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>Novel Cardioprotective Effect of L-Carnitine on Obese Diabetic Mice: Regulation of Chemerin and CMKLRI Expression in Heart and Adipose Tissues</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <name>
            <surname>Amiri</surname>
            <given-names>Rezvan</given-names>
          </name>
          <xref ref-type="aff" rid="aff1001">
            <sup>1</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0003-3258-8550</contrib-id>
          <name>
            <surname>Tabandeh</surname>
            <given-names>Mohammad Reza</given-names>
          </name>
          <xref ref-type="aff" rid="aff1001">
            <sup>1</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Hosseini</surname>
            <given-names>Seyed Ahmad</given-names>
          </name>
          <xref ref-type="aff" rid="aff2001">
            <sup>2</sup>
          </xref>
        </contrib>
      </contrib-group>
      <aff id="aff1001">
        <label>1</label>
        <country country="IR">Iran</country>
        <institution content-type="original">Department of Basic Sciences, Division of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz &#8211; Iran</institution>
      </aff>
      <aff id="aff2001">
        <label>2</label>
        <country country="IR">Iran</country>
        <institution content-type="original">Department of Nutrition Science, Ahvaz Jundishapur University of Medical Sciences, Ahvaz &#8211; Iran</institution>
      </aff>
      <author-notes>
        <corresp id="c01001">Mailing Address: Mohammad Reza Tabandeh &#8226; Department of Basic Sciences, Division of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, 61355-145, Ahvaz, Iran E-mail: m.tabandeh@scu.ac.ir</corresp>
        <fn fn-type="con">
          <p>Author Contributions</p>
          <p>Conception and design of the research: Tabandeh MR, Hosseini SA; Acquisition of data: Amiri R; Analysis and interpretation of the data: Amiri R, Tabandeh MR, Hosseini SA; Statistical analysis: Amiri R, Tabandeh MR, Hosseini SA; Obtaining financing and Critical revision of the manuscript for intellectual content: Tabandeh MR; Writing of the manuscript: Amiri R, Tabandeh MR.</p>
        </fn>
        <fn fn-type="conflict">
          <p>Potential Conflict of Interest</p>
          <p>No potential conflict of interest relevant to this article was reported.</p>
        </fn>
      </author-notes>
      <abstract>
        <title>Abstract</title>
        <sec>
          <title>Background</title>
          <p>L-carnitine (LC) has many beneficial effects on diabetic animals and humans, but its regulatory effect on chemerin as an inflammatory cytokine, and its receptor in diabetes status is unknown.</p>
        </sec>
        <sec>
          <title>Objectives</title>
          <p>The present study aimed to investigate the regulatory effect of LC on the expression of chemerin and chemokine-like receptor I (CMKLRI) in adipose and cardiac tissues of diabetic mice.</p>
        </sec>
        <sec>
          <title>Methods</title>
          <p>Sixty NMARI mice were divided into four groups including control, diabetic, diabetic + LC supplementation and control + LC supplementation. Diabetes was induced by feeding the animals a high-calorie diet for 5 weeks and injection of Streptozotocin. The animals were treated with 300 mg/kg LC for 28 days. On days 7, 14, and 28 after treatment, the mRNA and protein levels of chemerin and CMKLRI in the cardiac and adipose tissues of the animals were determined using qPCR analysis and ELISA. Insulin resistance indices were also measured in all experimental groups. Differences with p &lt;0.05 were considered significant.</p>
        </sec>
        <sec>
          <title>Results</title>
          <p>Chemerin and CMKLRI expressions levels were increased in cardiac and adipose tissues of diabetic mice on days 14 and 28 after diabetes induction, concurrent with the incidence of insulin resistance and increased levels of circulating chemerin (p&lt;0.05). The treatment with LC caused a significant decrease in the expression of both genes in studied tissues and the reduction of insulin resistance symptoms and serum chemerin levels (p&lt;0.05).</p>
        </sec>
        <sec>
          <title>Conclusion</title>
          <p>The results suggest that LC treatment were able to downregulate the expression of chemerin and CKLR1 in cardiac and adipose tissues of obese, diabetic experimental animals.</p>
        </sec>
      </abstract>
      <kwd-group xml:lang="en">
        <kwd>Diabetes Mellitus</kwd>
        <kwd>Carnitine</kwd>
        <kwd>Chemokines</kwd>
      </kwd-group>
    </front-stub>
    <body>
      <sec sec-type="intro">
        <title>Introduction</title>
        <p>A growing body of evidence has shown the existence of a complex and multifaceted biochemical and molecular relationship between diabetes mellitus (DM), obesity and cardiovascular diseases (CVDs).<sup><xref ref-type="bibr" rid="B1">1</xref></sup> One possible mechanism linking DM and obesity with subsequent CVDs is low-grade inflammation in adipose tissue.<sup><xref ref-type="bibr" rid="B2">2</xref></sup> The adipose tissue of animals or humans with DM and insulin resistance secretes a variety of cytokines or adipocytokines. The abnormal secretion of these adipocytokines contributes to increased inflammation and lipid accumulation and can lead to the development of endothelial and myocardial dysfunction and cardiomyopathies.<sup><xref ref-type="bibr" rid="B2">2</xref> , <xref ref-type="bibr" rid="B3">3</xref></sup> The alterations in the expression or secretion of pro-inflammatory and anti-inflammatory adipokines in cardiomyocytes and adipose tissue have been implicated in the pathogenesis of metabolic syndrome and CVDs in obese animals or humans.<sup><xref ref-type="bibr" rid="B2">2</xref></sup></p>
        <p>Chemerin is a recently identified adipokine that acts as a chemoattractant protein and mediates its effects through a G-protein coupled receptor, the chemokine-like receptor 1 (CMKLRI), also known as ChemR23.<sup><xref ref-type="bibr" rid="B4">4</xref> - <xref ref-type="bibr" rid="B7">7</xref></sup> Previous studies demonstrated that chemerin had a role in various cardiovascular pathologies, including the development of hypertension, progression of atherosclerotic lesions, and impaired heart function in patients with dilated cardiomyopathy.<sup><xref ref-type="bibr" rid="B8">8</xref></sup> Chemerin can promote endothelial inflammation, and induce apoptosis in murine cardiomyocytes, demonstrating the potential role of chemerin in cardiomyocyte dysfunctions.<sup><xref ref-type="bibr" rid="B9">9</xref> , <xref ref-type="bibr" rid="B10">10</xref></sup></p>
        <p>Recently, mitochondrial-targeting nutrients, such as lipoic acid, L-carnitine (LC), nicotinamide and biotin have been given more attention regarding the improvement of diabetes-related inflammatory and cardiovascular complications.<sup><xref ref-type="bibr" rid="B11">11</xref> , <xref ref-type="bibr" rid="B12">12</xref></sup> L-carnitine (LC) is a conditionally essential nutrient that facilitates fatty acid transport to the oxidation sites in the mitochondria.<sup><xref ref-type="bibr" rid="B13">13</xref> , <xref ref-type="bibr" rid="B14">14</xref></sup></p>
        <p>There is increasing evidence that LC supplementation may be beneficial in treating insulin-resistance and obesity-related metabolic disturbances in diabetic patients.<sup><xref ref-type="bibr" rid="B11">11</xref></sup> Various studies have shown that LC has beneficial effects on the prevention and improvement of cardiovascular disease, including chronic heart failure, anterior acute myocardial infarction, coronary artery disease, myocardial remodeling and atrial fibrillation.<sup><xref ref-type="bibr" rid="B12">12</xref> , <xref ref-type="bibr" rid="B14">14</xref></sup> Several mechanisms have been reported regarding the protective role of LC in cardiac cells under hyperglycemic conditions, including improvement of cardiac energy homeostasis, oxidative stress attenuation and hypoxic cell damage and apoptosis reduction.<sup><xref ref-type="bibr" rid="B15">15</xref> , <xref ref-type="bibr" rid="B16">16</xref></sup> Limited evidence has also shown that LC may affect serum chemerin levels in obese children.<sup><xref ref-type="bibr" rid="B17">17</xref></sup> Based on our knowledge, a few studies have focused on the role of LC supplementation on chemerin expression regulation, particularly in cardiac and adipose tissues of diabetic animals. The aim of the present study was to investigate the effects of LC supplementation on chemerin and CMKLRI expression in adipose and cardiac tissues in an experimental model of obesity and diabetes induced by a high-calorie diet fed to mice.</p>
      </sec>
      <sec sec-type="materials|methods">
        <title>Materials and methods</title>
        <sec>
          <title>Animals</title>
          <p>Sixty male NMARI mice (25&#177;2 g) were selected from the Center of Laboratory Animals of the School of Veterinary Medicine of Shahid Chamran University of Ahvaz, Iran. All the mice were kept under controlled environmental conditions, with an average temperature of 23 &#177; 1 &#176;C, a 12:12 h light/darkness cycle and free access to water and special diet for mice prepared as pellet (Pars, Tehran, Iran). All experimental protocols were approved by the Ethics Committee for Research in Animals and Humans of Shahid Chamran University of Ahvaz (EE/98.24.3.26209/SCU.AC.IR). All animal experimentations were carried out in accordance with the guidelines for the care and use of laboratory animals (NIH publication n. 86-23). There was an adaptation period of 7 days before the start of the experiment.</p>
        </sec>
        <sec>
          <title>Experimental design</title>
          <p>The animals (n=60) were randomly divided into four equal groups. Randomization was achieved by allocating the animals of the same sex, age and weight in different experimental groups using random number tables. Two groups were fed a high-energy diet, which was prepared by adding 20% sucrose (w/w) and 10% lard (w/w) into the diets for 5 weeks and described as HF/HC (n=30), whereas the other ones continued to consume normal diets for the same period, serving as a control groups (n=30). After 5-weeks receiving the HF/HC diets, the diabetic groups were treated with a single intraperitoneal injection of STZ (Sigma, Germany) (30 mg/kg body weight) prepared in a citrate buffer solution.<sup><xref ref-type="bibr" rid="B18">18</xref> , <xref ref-type="bibr" rid="B19">19</xref></sup></p>
          <p>Blood glucose was measured five days after STZ treatment using a hand-held glucometer (Medisign, China) and the presence of diabetes was confirmed if serum glucose was over 6.5 mmol/L and if the HOMA&#8211;IR was high in comparison to the control group.<sup><xref ref-type="bibr" rid="B20">20</xref></sup> The day following the confirmation of diabetes was considered as day 0 of LC treatment. One diabetic group was treated with LC at a dose of 300 mg/kg (n=15) in drinking water, while concomitantly being fed the HF/HC diets for 28 days, while the other diabetic group (n=15) (diabetic control) were fed only HF/HC diets for the same period.<sup><xref ref-type="bibr" rid="B18">18</xref> , <xref ref-type="bibr" rid="B19">19</xref></sup> One control group (n=15) that received a normal diet and the other control group (n=15) (LC-treated control) that consumed LC at dose of 300 mg/kg in drinking water for 28 days were also considered for the analyses.</p>
        </sec>
        <sec>
          <title>Sampling</title>
          <p>Animal euthanasia was carried out with a combination of ketamine (100 mg/kg) and xylazine (10 mg/kg) respectively, on days 0, 14 and 28 of LC treatment. Blood samples were collected, and sera were separated and stored at -20&#176;C for later use. Hearts and visceral adipose tissues were separated and kept at &#8211;70&#176;C until use.</p>
        </sec>
        <sec>
          <title>Biochemical parameter measurements</title>
          <p>Serum insulin and chemerin levels were determined using the species-specific ELISA kits (EastBiopharm, China). Serum glucose was measured by commercial kits (PishtazTeb, Iran) according to the manufacturer&#8217;s recommendations. Serum IL1-&#946; and TNF-&#945; levels were determined using species-specific ELISA kits, as recommended by the manufacturer (Biovision Inc. USA)</p>
        </sec>
        <sec>
          <title>HOMA&#8211;IR Estimation</title>
          <p>The HOMA-IR factor was calculated using the following formula:</p>
          <p>HOMA index = Fasting insulin (&#181;U/ml) &#215; Fasting glucose (mmol/L) /22.5. The rising and falling of HOMA&#8211;IR values in relation to control, healthy animals indicate increase and decrease in insulin sensitivity, respectively.<sup><xref ref-type="bibr" rid="B20">20</xref></sup></p>
        </sec>
        <sec>
          <title>RNA isolation and cDNA synthesis</title>
          <p>Total RNA was extracted from 100 mg of heart and adipose tissues using RNX<sup>TM</sup>isolation reagent according to the manufacturer&#8217;s procedure (SinaClon, Tehran, Iran). The samples were treated with DNase I enzyme to avoid DNA contamination. The purity of RNA at a 260/280 OD ratio and RNA integrity were evaluated using an Eppendorf &#181;Cuvette G1.0 microvolume measuring cell (Eppendorf BioPhotometer D30, Eppendorf, Germany). Reverse transcription was performed with the YTA cDNA synthesis kit (Yekta tajhiz, Iran) and Eppendorf Thermal Cycler (Germany) using 1 &#181;g of RNA and random hexamer, as recommended by the manufacturer.</p>
        </sec>
        <sec>
          <title>Real-time quantitative RT-PCR</title>
          <p>Real-time PCR was performed using the Roche Light-Cycler detection system (Basel, Switzerland) with the qPCR<sup>TM</sup>Green Master Kit for SYBR Green I<sup>&#174;</sup>(Yektatajhiz, Iran). The relative expression level of the chemerin and CMKLRI transcripts were compared to mice GAPDH as the housekeeping gene. Specific sets of primers (Pishgam BioTech, Co, Tehran, Iran) designed for this study were: chemerin (GenBank:NC-007299): 5&#8217;- TCTTCACCTACGACCAGTATCAG -3&#8217; and 5&#8217;- ACATTATCTGCATAGACCCCATTG -3&#8217; and <italic>CMKLRI</italic> (GenBank:NM-008153.3): 5&#8217;- GTACGACGCTTACAACGACT -3&#8217; and 5&#8217;- GCACACCAAGCTGTAGATCA -3&#8217;, <italic>GAPDH</italic> (GenBank:NM-001034055): 5&#8217;- CTCATCTACCTCTCCATCGTCTG -3&#8217; and 5&#8217;- CCTGCTCTTGTCTGCCGGTGCTTG -3&#8217; The PCR protocol used consisted of a 5 min denaturation at 94&#176;C followed by 45 cycles at 94<sup>o</sup>C for 15 sec, 60<sup>o</sup>C for 30 sec. Two separate reactions without cDNA or with RNA were performed in parallel as controls. The relative quantification was performed according to the comparative 2<sup>-</sup>method and using Lightcycler 96<sup>&#174;</sup>software. Assay validation to check whether the primer for chemerin and CMKLRI and GAPDH had similar amplification efficiencies was performed as previously described. All qPCR analyses were performed according to The Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guideline.<sup><xref ref-type="bibr" rid="B21">21</xref></sup></p>
        </sec>
        <sec>
          <title>Determination of tissue chemerin protein</title>
          <p>Cardiac and adipose tissues were homogenized in 500 &#956;l RIPA lysis buffer (NaCl; 150 mM, SDS 0.1%, Tris; 25 mM, pH 7.4, NaF; 1 mM, Phenylmethylsulfonyl fluoride 1 mM) with a homogenizer (Heidolph, Schwabach, Germany). The homogenate was centrifuged at 10000&#215;RPM for 15 min at 4&#176;C (Centrifuge 5415 R; Eppendorf AG, Hamburg, Germany). The supernatant was collected and stored at -70&#176;C for subsequent analysis. Protein concentration in the supernatant was estimated using the Bradford method. Chemerin concentration was determined using the species-specific ELISA kits (East Biopharm, China) and expressed as ng/mg of tissue protein.</p>
        </sec>
        <sec>
          <title>Statistical analyses</title>
          <p>Statistical analysis was conducted using the SPSS 22 software (SPSS Inc., Chicago, IL, USA). All data were presented as mean &#177; standard deviation (SD). The Shapiro&#8211;Wilk <italic>or Levene's test</italic> was used to <italic>determine</italic> the normality of data or equality of <italic>error variances</italic> . All parameters were statistically analyzed by three-way analysis of variance (ANOVA) with sampling times, LC treatment and diabetic condition as factors. When the interaction and/or the main effects were significant, means were compared between different experimental groups at different time points using Tukey&#8217;s multiple-comparison post-hoc test. Graphs were drawn using Graphpad Prism 8 (GraphPad Software Inc., San Diego, CA, USA). We did not use any statistical methods to predetermine sample size. Samples sizes were estimated based on sample availability, ethical issues about accomplishing experimental aims without having to use numerous animals and previous experimental studies.<sup><xref ref-type="bibr" rid="B11">11</xref> , <xref ref-type="bibr" rid="B16">16</xref></sup> A <italic>p</italic> -value below 0.05 was considered statistically significant.</p>
        </sec>
      </sec>
      <sec sec-type="results">
        <title>Results</title>
        <p>Our results showed that consumption of a 5-week high calorie diet, concurrent with low-dose injection of STZ induced a T2DM phenotype that was characterized by hyperinsulinemia and hyperglycemia. The effect of the main factors (Diabetic condition, 2 levels; LC treatment, 2 levels; and sampling time, 3 levels) and their interaction with each variable are shown in <xref ref-type="table" rid="t1001">Table 1</xref> . A three-way ANOVA analysis indicated a main effect of sampling time (p = 0.0031), LC treatment (p = 0.0001), diabetic condition (p = 0.0001) and the interaction of sampling time &#215;LC treatment &#215; diabetic condition (p = 0.0018) on insulin levels in different experimental groups ( <xref ref-type="table" rid="t1001">Table 1</xref> ). Changes in serum insulin levels in diabetic mice treated with LC are shown in <xref ref-type="fig" rid="f01001">Figure 1A</xref> . Serum levels of insulin were significantly increased at day 7 after diabetes induction (day 0 of LC treatment) in relation to healthy, control animals and it remained high until day 28 of the experiment (p&lt;0.05). Serum insulin levels were significantly decreased in diabetic mice after two and four weeks of treatment with LC, when compared to untreated diabetic mice (p&lt;0.05) ( <xref ref-type="fig" rid="f01001">Figure 1A</xref> ). Treatment of diabetic mice with LC for a longer period, between 14 and 28 days of treatment, was no more effective in reducing insulin levels (p&gt;0.05) ( <xref ref-type="fig" rid="f01001">Figure 1A</xref> ).</p>
        <p>
          <table-wrap id="t1001">
            <label>Table 1</label>
            <caption>
              <title>&#8211; Results of three-way ANOVA analysis to determine the effects of the diabetic condition (D), Sampling time (ST) and LC treatment (LC) and their interactions (D &#215; ST &#215; LC) on each variable.</title>
            </caption>
            <table frame="hsides" rules="groups">
              <colgroup>
                <col/>
                <col/>
                <col/>
                <col/>
                <col/>
                <col/>
                <col/>
                <col/>
                <col/>
              </colgroup>
              <thead>
                <tr>
                  <th align="left" rowspan="5">Variable</th>
                  <th colspan="6">Main factors</th>
                  <th colspan="2">Interactions of main factors</th>
                </tr>
                <tr>
                  <th colspan="8" rowspan="1">
                    <hr/>
                  </th>
                </tr>
                <tr>
                  <th colspan="2">Diabetic condition (D)</th>
                  <th colspan="2">LC treatment (LC)</th>
                  <th colspan="2">Sampling times (ST)</th>
                  <th colspan="2">D&#215;LC&#215;ST</th>
                </tr>
                <tr>
                  <th colspan="8" rowspan="1">
                    <hr/>
                  </th>
                </tr>
                <tr>
                  <th>p value</th>
                  <th>F (1.48)</th>
                  <th>p value</th>
                  <th>F (1.48)</th>
                  <th>p value</th>
                  <th>F (2.48)</th>
                  <th>p value</th>
                  <th>F (2.48)</th>
                </tr>
              </thead>
              <tbody>
                <tr>
                  <td>Insulin</td>
                  <td align="center">p = 0.0001</td>
                  <td align="center">305.92</td>
                  <td align="center">p = 0.0001</td>
                  <td align="center">17.41</td>
                  <td align="center">p = 0.0031</td>
                  <td align="center">4.89</td>
                  <td align="center">p = 0.0018</td>
                  <td align="center">3.73</td>
                </tr>
                <tr>
                  <td>Glucose</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">6182.2</td>
                  <td align="center">p = 0.0005</td>
                  <td align="center">1248.2</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">634.6</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">67.59</td>
                </tr>
                <tr>
                  <td>HOMA-IR</td>
                  <td align="center">p = 0.0005</td>
                  <td align="center">447.02</td>
                  <td align="center">p = 0.0017</td>
                  <td align="center">12.95</td>
                  <td align="center">p = 0.0019</td>
                  <td align="center">8.12</td>
                  <td align="center">p = 0.0015</td>
                  <td align="center">8.91</td>
                </tr>
                <tr>
                  <td>Adipose chemerin mRNA</td>
                  <td align="center">p = 0.0003</td>
                  <td align="center">1761.2</td>
                  <td align="center">p = 0.0003</td>
                  <td align="center">1040.3</td>
                  <td align="center">p = 0.0008</td>
                  <td align="center">125.45</td>
                  <td align="center">p = 0.0007</td>
                  <td align="center">319.21</td>
                </tr>
                <tr>
                  <td>Cardiac chemerin mRNA</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">5546.3</td>
                  <td align="center">p = 0.0001</td>
                  <td align="center">187.6</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">73.36</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">67.9</td>
                </tr>
                <tr>
                  <td>Adipose chemerin protein</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">2267.2</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">762.21</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">70.23</td>
                  <td align="center">p = 0.0003</td>
                  <td align="center">64.22</td>
                </tr>
                <tr>
                  <td>Cardiac chemerin protein</td>
                  <td align="center">p = 0.0003</td>
                  <td align="center">1651.4</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">641.22</td>
                  <td align="center">p = 0.0003</td>
                  <td align="center">62.27</td>
                  <td align="center">p = 0.0004</td>
                  <td align="center">64.12</td>
                </tr>
                <tr>
                  <td>Adipose CMKLR1 mRNA</td>
                  <td align="center">p = 0.0001</td>
                  <td align="center">8376.2</td>
                  <td align="center">p = 0.0001</td>
                  <td align="center">306.99</td>
                  <td align="center">p = 0.0001</td>
                  <td align="center">96.51</td>
                  <td align="center">p = 0.0001</td>
                  <td align="center">65.73</td>
                </tr>
                <tr>
                  <td>Cardiac CMKLR1 mRNA</td>
                  <td align="center">p = 0.0001</td>
                  <td align="center">2172.3</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">65.04</td>
                  <td align="center">p = 0.0003</td>
                  <td align="center">75.59</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">7.37</td>
                </tr>
                <tr>
                  <td>Serum chemerin</td>
                  <td align="center">p = 0.0003</td>
                  <td align="center">3759.4</td>
                  <td align="center">p = 0.0005</td>
                  <td align="center">183.59</td>
                  <td align="center">p = 0.0003</td>
                  <td align="center">423.2</td>
                  <td align="center">p = 0.0003</td>
                  <td align="center">91.87</td>
                </tr>
                <tr>
                  <td>IL1-&#946;</td>
                  <td align="center">p = 0.0005</td>
                  <td align="center">2042.1</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">53.12</td>
                  <td align="center">p = 0.0004</td>
                  <td align="center">375.6</td>
                  <td align="center">p = 0.0008</td>
                  <td align="center">68.46</td>
                </tr>
                <tr>
                  <td>TNF-&#945;</td>
                  <td align="center">p = 0.0001</td>
                  <td align="center">4644.3</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">475.6</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">2516.2</td>
                  <td align="center">p = 0.0002</td>
                  <td align="center">439.17</td>
                </tr>
              </tbody>
            </table>
          </table-wrap>
        </p>
        <p>
          <fig id="f01001">
            <label>Figure 1</label>
            <caption>
              <title>&#8211; <italic>Serum levels of insulin (A), Glucose (B) and HOMA-IR in different experimental groups on days 0, 14 and 28 of LC treatment. Data are shown as means &#177; SD. The level of significance between groups at each sampling time was set at *p&lt; 0.05, **p&lt; 0.01, *** p&lt; 0.001, **** p&lt; 0.0001.</italic></title>
            </caption>
            <graphic xlink:href="1678-4170-abc-117-04-0715-00044-gf01-en.tif"/></fig>
        </p>
        <p>A three-way ANOVA analysis indicated a main effect of sampling time <italic>(</italic> p = 0.0002), LC treatment (p = 0.0005), diabetic condition (p = 0.0002) and interaction of sampling time &#215; LC treatment &#215; diabetic condition (p = 0.0002) on serum glucose levels in different experimental groups. The serum glucose levels were found to be significantly higher in diabetic mice on days 14 and 28 after diabetes induction compared with healthy animals (p&lt;0.05), while administration of HF/HC supplemented diet and STZ injection had no significant effect on serum glucose levels during the first one week of experimental induction of diabetes (p&gt;0.05) ( <xref ref-type="fig" rid="f01001">Figure 1B</xref> ). It was observed that the treatment of <italic>diabetic mice with LC</italic> resulted in a significant reduction of blood sugar levels, as observed on days 14 and 28 when compared with diabetic, untreated mice (p&lt;0.05) ( <xref ref-type="fig" rid="f01001">Figure 1B</xref> ). LC intake had no obvious effect on serum glucose levels in healthy mice (p&gt;0.05) ( <xref ref-type="fig" rid="f01001">Figure 1B</xref> ).</p>
        <p>A three-way ANOVA analysis indicated a main effect of sampling time <italic>(</italic> p = 0.0019), LC treatment (p = 0.0017), diabetic condition (p = 0.0005) and interaction of sampling time &#215; LC treatment &#215; diabetic condition <italic>(</italic> p = 0.0015) on HOMA-IR in different experimental groups. HOMA-IR in diabetic animals was found to significantly increase on days 14 and 28 of the experimental period in relation to healthy mice (p&lt;0.05), while it showed no significant change in the first week after the experimental induction of diabetes (p&gt;0.05) ( <xref ref-type="fig" rid="f01001">Figure 1C</xref> ). Oral administration of LC had a significant lowering effect on HOMA-IR on days 14 and 28 of the experimental period in diabetic mice (p&lt;0.05) ( <xref ref-type="fig" rid="f01001">Figure 1C</xref> ). As shown in <xref ref-type="fig" rid="f01001">Fig. 2</xref> , higher body weight was observed in mice that received HF/HC supplemented diet at all times of the experiment, when compared with healthy mice (p&lt;0.05). During the four weeks of observation of the LC-treated diabetic mice, the latter showed weight loss, relative to day 0, i.e., before the start of the treatment (p&lt;0.05) ( <xref ref-type="fig" rid="f02001">Figure 2</xref> ).</p>
        <p>
          <fig id="f02001">
            <label>Figure 2</label>
            <caption>
              <title>&#8211; <italic>Changes in body weight in different experimental groups on days 0, 14 and 28 of LC treatment. Data are means &#177; SD. The level of significance between groups at each sampling time was set at *p&lt; 0.05, **p&lt; 0.01, *** p&lt; 0.001, **** p&lt; 0.0001.</italic></title>
            </caption>
            <graphic xlink:href="1678-4170-abc-117-04-0715-00044-gf02-en.tif"/></fig>
        </p>
        <p>Regarding serum chemerin levels, a three-way ANOVA analysis showed a main effect of sampling time (p = 0.0003), LC treatment <italic>(</italic> p = 0.0005), diabetic condition (p = 0.0003) and interaction of sampling time &#215; LC treatment &#215; diabetic condition (p = 0.0003). Our results showed that serum chemerin levels were significantly higher in the diabetic group than in the control group at all sampling times, with the highest level being observed on day 28 of the experiment (p&lt;0.05). After two weeks of LC treatment, serum chemerin levels of diabetic mice showed no significant difference with those of untreated diabetic mice (p &gt; 0.05), while a significant lowering effect on serum chemerin levels was observed when diabetic mice consumed LC for 28 days (p&lt;0.05) ( <xref ref-type="fig" rid="f03001">Figure 3</xref> ).</p>
        <p>
          <fig id="f03001">
            <label>Figure 3</label>
            <caption>
              <title>&#8211; <italic>Serum levels of chemerin in different experimental groups on days 0, 14 and 28 of LC treatment. Data are shown as means &#177; SD. The level of significance between groups at each sampling time was set at *p&lt; 0.05, **p&lt; 0.01, *** p&lt; 0.001, **** p&lt; 0.0001.</italic></title>
            </caption>
            <graphic xlink:href="1678-4170-abc-117-04-0715-00044-gf03-en.tif"/></fig>
        </p>
        <p>As for the chemerin and CMKLR1 mRNA levels in cardiac muscle, a three-way ANOVA analysis showed a main effect of sampling time (chemerin p = 0.0001, CMKLR1 p = 0.0003), LC treatment (chemerin; p = 0.0002, CMKLR1 p = 0.0002), diabetic condition (chemerin; p = 0.0002, CMKLR1 p = 0.0001) and interaction between the three factors (chemerin; p &lt; 0.0001, CMKLR1 p = 0.0002). The mRNA and protein levels of chemerin and CMKLRI in cardiac tissue of diabetic mice were higher than that in normal animals at all sampling times after diabetes induction (p&lt;0.05) ( <xref ref-type="fig" rid="f04001">Figure 4</xref> and <xref ref-type="table" rid="t2001">Table 2</xref> ). Oral consumption of LC for two weeks had no significant effect on the reduction of chemerin or CMKLRI expression in cardiac tissue of diabetic mice (p&gt;0.05), while the expression of the studied genes was reduced in cardiac tissue of diabetic mice after 28 days of LC treatment, when compared with that in diabetic, untreated animals (p&lt;0.05) ( <xref ref-type="fig" rid="f04001">Figure 4</xref> , <xref ref-type="table" rid="t2001">Table 2</xref> ).</p>
        <p>
          <fig id="f04001">
            <label>Figure 4</label>
            <caption>
              <title>&#8211; <italic>Gene expression levels of chemerin (A) and CMKLRI (B) in adipose tissue of different experimental groups on days 0, 14 and 28 of LC treatment. The qRT-PCR method was used for the analysis of the relative expression of studied genes. GAPDH was used as the housekeeping gene. The level of significance between the groups at each sampling time was set at *p&lt; 0.05, **p&lt; 0.01, *** p&lt; 0.001, **** p&lt; 0.0001.</italic></title>
            </caption>
            <graphic xlink:href="1678-4170-abc-117-04-0715-00044-gf04-en.tif"/></fig>
        </p>
        <p>
          <table-wrap id="t2001">
            <label>Table 2</label>
            <caption>
              <title>&#8211; Concentration of chemerin in cardiac tissue of experimental groups. Data are shown as mean &#177; SD. Different lower-case letters (a,b) demonstrate significant differences between groups in each day of the experiment (p &lt; 0.05). Different upper-case letters (A,B) demonstrate significant differences between times of treatment in each group (p &lt; 0.05)</title>
            </caption>
            <table frame="hsides" rules="groups">
              <colgroup>
                <col/>
                <col/>
                <col/>
                <col/>
              </colgroup>
              <thead>
                <tr>
                  <th colspan="4">Cardiac tissue chemerin level (ng/mg protein)</th>
                </tr>
                <tr>
                  <th colspan="4">
                    <hr/>
                  </th>
                </tr>
                <tr>
                  <th colspan="4">Days of LC treatment</th>
                </tr>
                <tr>
                  <th colspan="4">
                    <hr/>
                  </th>
                </tr>
                <tr>
                  <th align="left" style="font-weight:normal"> </th>
                  <th>0</th>
                  <th>14</th>
                  <th>28</th>
                </tr>
              </thead>
              <tbody>
                <tr>
                  <td>Control</td>
                  <td align="center">2.47 &#177; 0.42<sup>aA</sup></td>
                  <td align="center">2.56 &#177; 0.27<sup>aA</sup></td>
                  <td align="center">2.27 &#177; 0.22<sup>aA</sup></td>
                </tr>
                <tr>
                  <td>Diabetic</td>
                  <td align="center">3.01 &#177; 0.31<sup>aA</sup></td>
                  <td align="center">4.97 &#177; 0.48<sup>bB</sup></td>
                  <td align="center">5.51 &#177; 0.41<sup>bB</sup></td>
                </tr>
                <tr>
                  <td>Diabetic + LC</td>
                  <td align="center">2.81 &#177; 0.16<sup>aA</sup></td>
                  <td align="center">4.42 &#177; 0.38<sup>bB</sup></td>
                  <td align="center">3.13 &#177; 0.29<sup>cA</sup></td>
                </tr>
                <tr>
                  <td>Control + LC</td>
                  <td align="center">2.32 &#177; 0.38<sup>aA</sup></td>
                  <td align="center">2.67 &#177; 0.33<sup>aA</sup></td>
                  <td align="center">2.37 &#177; 0.28<sup>aA</sup></td>
                </tr>
              </tbody>
            </table>
            <table-wrap-foot>
              <fn id="TFN1001">
                <p>
                  <italic>LC: l-carnitine.</italic>
                </p>
              </fn>
            </table-wrap-foot>
          </table-wrap>
        </p>
        <p>Regarding adipose chemerin and CMKLR1 mRNA and protein levels, a three-way ANOVA analysis showed a main effect of sampling time (chemerin; p = 0.0008, CMKLR1 p = 0.0001), LC treatment (chemerin; p = 0.0003, CMKLR1 p = 0.0001), diabetic condition (chemerin; p = 0.0003, CMKLR1 p = 0.0001) and interaction between three factors (chemerin; p = 0.0007, CMKLR1 p = 0.0001). It was observed that animals that received HF/HC supplemented diet had higher protein and mRNA levels of chemerin and CMKLRI in adipose tissue on days 7 , 14 and 28 after the final feeding when compared with animals that received a normal diet (p&lt;0.05) ( <xref ref-type="fig" rid="f05001">Figure 5 A-B</xref> , <xref ref-type="table" rid="t3001">Table 3</xref> ). The treatment of diabetic mice with LC for 14 or 28 days resulted in a significant reduction in chemerin protein and mRNA levels in adipose tissue of diabetic animals when compared with untreated, diabetic mice (p&lt;0.05) ( <xref ref-type="fig" rid="f05001">Figure 5A</xref> , <xref ref-type="table" rid="t2001">Table 2</xref> ). Animals that received LC for 14 days showed no significant change in CMKLRI expression (p&gt;0.05), while those that were treated with LC for 28 days had a lower expression of CMKLRI when compared with untreated, diabetic mice (p&lt;0.05) ( <xref ref-type="fig" rid="f05001">Figure 5B</xref> ).</p>
        <p>
          <fig id="f05001">
            <label>Figure 5</label>
            <caption>
              <title>&#8211; <italic>Gene expression levels of chemerin (A) and CMKLRI (B) in cardiac tissue of different experimental groups on days 0, 14 and 28 of LC treatment. The qRT-PCR method was used for the analysis of the relative expression of studied genes. GAPDH was used as the housekeeping gene. Data are shown as means &#177; SD. The level of significance between groups at each sampling time was set at *p&lt; 0.05, **p&lt; 0.01, *** p&lt; 0.001, **** p&lt; 0.0001.</italic></title>
            </caption>
            <graphic xlink:href="1678-4170-abc-117-04-0715-00044-gf05-en.tif"/></fig>
        </p>
        <p>
          <table-wrap id="t3001">
            <label>Table 3</label>
            <caption>
              <title>&#8211; Concentration of chemerin in adipose tissue of different experimental groups. Data are presented as mean &#177; SD. Different lower-case letters (a,b) demonstrate significant differences between groups in each day of the experiment (p &lt; 0.05). Different upper-case letters (A,B) demonstrate significant differences between times of treatment in each group (p &lt; 0.05)</title>
            </caption>
            <table frame="hsides" rules="groups">
              <colgroup>
                <col/>
                <col/>
                <col/>
                <col/>
              </colgroup>
              <thead>
                <tr>
                  <th colspan="4">Adipose tissue chemerin level (ng/mg protein)</th>
                </tr>
                <tr>
                  <th colspan="4">
                    <hr/>
                  </th>
                </tr>
                <tr>
                  <th colspan="4">Days of LC treatment</th>
                </tr>
                <tr>
                  <th colspan="4">
                    <hr/>
                  </th>
                </tr>
                <tr>
                  <th align="left" style="font-weight:normal"> </th>
                  <th>0</th>
                  <th>14</th>
                  <th>28</th>
                </tr>
              </thead>
              <tbody>
                <tr>
                  <td>Control</td>
                  <td align="center">7.62 &#177; 2.58<sup>aA</sup></td>
                  <td align="center">8.11 &#177; 1.32<sup>aA</sup></td>
                  <td align="center">6.49 &#177; 1.07<sup>aA</sup></td>
                </tr>
                <tr>
                  <td>Diabetic</td>
                  <td align="center">13.22 &#177; 3.61<sup>bA</sup></td>
                  <td align="center">14.78 &#177; 2.59<sup>bA</sup></td>
                  <td align="center">16.72 &#177; 97<sup>bB</sup></td>
                </tr>
                <tr>
                  <td>Diabetic + LC</td>
                  <td align="center">12.64 &#177; 2.09<sup>bA</sup></td>
                  <td align="center">10.36 &#177; 1.78<sup>cB</sup></td>
                  <td align="center">10.97 &#177; 3.12<sup>bB</sup></td>
                </tr>
                <tr>
                  <td>Control + LC</td>
                  <td align="center">6.82 &#177; 1.94<sup>aA</sup></td>
                  <td align="center">7.09 &#177; 2.06<sup>aA</sup></td>
                  <td align="center">7.44 &#177; 1.19<sup>aA</sup></td>
                </tr>
              </tbody>
            </table>
            <table-wrap-foot>
              <fn id="TFN2001">
                <p>
                  <italic>LC: l-carnitine.</italic>
                </p>
              </fn>
            </table-wrap-foot>
          </table-wrap>
        </p>
        <p>Regarding serum IL1-&#946; and TNF-&#945; levels, a three-way ANOVA analysis showed a main effect of sampling time (IL1-&#946;; p = 0.0004 and TNF-&#945;; p = 0.0002), treatment <italic>(</italic> IL1-&#946;; p p = 0.0002 and TNF-&#945;; p = 0.0002) diabetic condition (IL1-&#946;; p = 0.0005, TNF-&#945; p = 0.0001) and interaction between the three factors (IL1-&#946;; p = 0.0008, TNF-&#945; p = 0.0002). Serum IL1-&#946; and TNF-&#945; levels were significantly increased in the diabetic group when compared to the control group on days 14 and 28 after induction of diabetes (p &lt;0.05) ( <xref ref-type="table" rid="t4001">Tables 4</xref> and <xref ref-type="table" rid="t5001">5</xref> ). The treatment of diabetic mice with LC for 14 days had no significant effects on serum levels of IL-1&#946; and TNF-&#945; compared to untreated diabetic mice (p&gt;0.05). However, four weeks after treatment with LC, serum levels of both inflammatory factors were significantly reduced, when compared to untreated diabetic mice.</p>
        <p>
          <table-wrap id="t4001">
            <label>Table 4</label>
            <caption>
              <title>&#8211; Serum concentration of IL1-&#946; in different experimental groups. Data are presented as mean &#177; SD. Different lower-case letters (a,b) demonstrate significant differences between groups on each day of the experiment (p &lt; 0.05). Different upper-case letters (A,B) demonstrate significant differences between times of treatment in each group (p &lt; 0.05)</title>
            </caption>
            <table frame="hsides" rules="groups">
              <colgroup>
                <col/>
                <col/>
                <col/>
                <col/>
              </colgroup>
              <thead>
                <tr>
                  <th colspan="4">Serum TNF-&#945; (pmol/L)</th>
                </tr>
                <tr>
                  <th colspan="4">
                    <hr/>
                  </th>
                </tr>
                <tr>
                  <th colspan="4">Days of LC treatment</th>
                </tr>
                <tr>
                  <th colspan="4">
                    <hr/>
                  </th>
                </tr>
                <tr>
                  <th align="left" style="font-weight:normal"> </th>
                  <th>0</th>
                  <th>14</th>
                  <th>28</th>
                </tr>
              </thead>
              <tbody>
                <tr>
                  <td>Control</td>
                  <td align="center">0.71 &#177; 0.19<sup>aA</sup></td>
                  <td align="center">0.65 &#177; 0.10<sup>aA</sup></td>
                  <td align="center">0.75 &#177; 0.09<sup>aA</sup></td>
                </tr>
                <tr>
                  <td>Diabetic</td>
                  <td align="center">0.65 &#177; 0.11<sup>aA</sup></td>
                  <td align="center">3.92 &#177; 0.38<sup>bB</sup></td>
                  <td align="center">7.10 &#177; 0.68<sup>bC</sup></td>
                </tr>
                <tr>
                  <td>Diabetic + LC</td>
                  <td align="center">1.33 &#177; 0.16<sup>bA</sup></td>
                  <td align="center">3.34 &#177; 0.50<sup>bB</sup></td>
                  <td align="center">3.94 &#177; 0.43<sup>cB</sup></td>
                </tr>
                <tr>
                  <td>Control + LC</td>
                  <td align="center">0.78 &#177; 0.18<sup>aA</sup></td>
                  <td align="center">0.98 &#177; 0.16<sup>aA</sup></td>
                  <td align="center">0.57 &#177; 0.11<sup>dB</sup></td>
                </tr>
              </tbody>
            </table>
            <table-wrap-foot>
              <fn id="TFN3001">
                <p>
                  <italic>LC: l-carnitine.</italic>
                </p>
              </fn>
            </table-wrap-foot>
          </table-wrap>
        </p>
        <p>
          <table-wrap id="t5001">
            <label>Table 5</label>
            <caption>
              <title>&#8211; Serum concentration of TNF-&#945; in different experimental groups on days 0, 14 and 28 of LC treatment. Data are presented as mean &#177; SD. Different lower-case letters (a,b) demonstrate significant differences between groups in each day of the experiment (p &lt; 0.05). Different upper-case letters (A,B) demonstrate significant differences between times of treatment in each group (p &lt; 0.05)</title>
            </caption>
            <table frame="hsides" rules="groups">
              <colgroup>
                <col/>
                <col/>
                <col/>
                <col/>
              </colgroup>
              <thead>
                <tr>
                  <th colspan="4">Serum IL1-&#946; (pmol/L)</th>
                </tr>
                <tr>
                  <th colspan="4">
                    <hr/>
                  </th>
                </tr>
                <tr>
                  <th colspan="4">Days of LC treatment</th>
                </tr>
                <tr>
                  <th colspan="4">
                    <hr/>
                  </th>
                </tr>
                <tr>
                  <th align="left" style="font-weight:normal"> </th>
                  <th>0</th>
                  <th>14</th>
                  <th>28</th>
                </tr>
              </thead>
              <tbody>
                <tr>
                  <td>Control</td>
                  <td align="center">0.93 &#177; 0.11<sup>aA</sup></td>
                  <td align="center">1.02 &#177; 0.14<sup>aA</sup></td>
                  <td align="center">0.89 &#177; 0.31<sup>aA</sup></td>
                </tr>
                <tr>
                  <td>Diabetic</td>
                  <td align="center">1.23 &#177; 0.33<sup>aA</sup></td>
                  <td align="center">2.96 &#177; 0.12<sup>bB</sup></td>
                  <td align="center">5.78 &#177; 0.21<sup>bB</sup></td>
                </tr>
                <tr>
                  <td>Diabetic + LC</td>
                  <td align="center">1.33 &#177; 0.26<sup>aA</sup></td>
                  <td align="center">2.23 &#177; 0.27<sup>bB</sup></td>
                  <td align="center">3.46 &#177; 0.12<sup>cC</sup></td>
                </tr>
                <tr>
                  <td>Control + LC</td>
                  <td align="center">1.07 &#177; 0.24<sup>aA</sup></td>
                  <td align="center">0.98 &#177; 0.19<sup>aA</sup></td>
                  <td align="center">0.82 &#177; 0.41<sup>aA</sup></td>
                </tr>
              </tbody>
            </table>
            <table-wrap-foot>
              <fn id="TFN4001">
                <p>
                  <italic>LC: l-carnitine.</italic>
                </p>
              </fn>
            </table-wrap-foot>
          </table-wrap>
        </p>
      </sec>
      <sec sec-type="discussion">
        <title>Discussion</title>
        <p>In the current study, the effect of LC supplementation on the expression of chemerin and its receptor in adipose and cardiac tissues of experimentally-induced obese and insulin resistant mice were studied. In accordance with previous studies using rodent models of type 2 diabetes, our results showed that a five week-consumption of a HF/HC supplemented diet, together with injection of a single low dose of STZ in mice resulted in insulin resistance and obesity, which was characterized by hyperglycemia, hyperinsulinemia and increased HOMA-IR and body weight.<sup><xref ref-type="bibr" rid="B16">16</xref> , <xref ref-type="bibr" rid="B18">18</xref> , <xref ref-type="bibr" rid="B19">19</xref></sup> It was observed that the HF/HC diet supplementation for five weeks resulted in hyperinsulinemia, with no obvious change in blood sugar levels, while after two weeks being fed a high calorie diet, the animals showed serum symptoms of insulin resistance, including hyperinsulinemia and hyperglycemia. These findings suggest that the serum metabolic alterations induced by this treatment were more similar to those of type 2 diabetes than of type 1 diabetes.</p>
        <p>Our results showed that expression of chemerin and its receptor, CMKLRI, in adipose and cardiac tissues of diabetic mice were increased after induction of experimental diabetes. It was also observed that diabetic animals had higher serum levels of chemerin when compared with healthy animals. This finding suggests that simultaneous changes that occur in the levels of chemerin and its receptor in the diabetic state exacerbates the function of this hormone in the target tissues and this may play an important role in the development of functional disturbances of adipose and cardiac tissues in the diabetic status. The bulk of human and animal data supports a relationship between chemerin, obesity and metabolic syndrome, a cluster of metabolic disorders that increase the risk of CVDs. In accordance with our results, human and animal studies reported the parallel findings that obese and diabetic animals have elevated circulating levels of chemerin compared with healthy or lean subjects or animals.<sup><xref ref-type="bibr" rid="B22">22</xref> , <xref ref-type="bibr" rid="B23">23</xref></sup> Several possible mechanisms may be assumed about the effects of increased expression of chemerin and CMKLRI on the initiation and progression of insulin resistance in diabetic animals. It is now known that inflammation has an important role in adipose tissue insulin resistance and cardiac muscle dysfunction.<sup><xref ref-type="bibr" rid="B24">24</xref></sup> Obesity is correlated with a significant increase in the production of proinflammatory cytokines, such as IL1&#946; and TNF&#945;, which can induce insulin resistance and cell death in the cardiac muscle.<sup><xref ref-type="bibr" rid="B25">25</xref> , <xref ref-type="bibr" rid="B26">26</xref></sup> Our findings showed the presence of increased serum levels of IL1&#946; and TNF&#945; following diabetes induction. Serum chemerin levels correlate with levels of proinflammatory cytokines, such as TNF-&#945;, IL1&#946; and IL-6.<sup><xref ref-type="bibr" rid="B6">6</xref> , <xref ref-type="bibr" rid="B7">7</xref> , <xref ref-type="bibr" rid="B25">25</xref></sup> Chemerin also has adverse effects on cardiomyocyte by induction of caspase-9 and Akt-mediated cell apoptosis.<sup><xref ref-type="bibr" rid="B10">10</xref></sup> Taken together, it is concluded that the observed overexpression of chemerin and its receptor in adipose and cardiac tissues of diabetic mice may have an important role in the progression of insulin resistance and cardiac dysfunctions in the diabetic status.</p>
        <p>Our results showed that LC administration for 4 weeks can attenuate the expression of chemerin and its receptor in adipose and cardiac tissues of diabetic mice. These alterations were associated with an improvement in insulin resistance symptoms and a reduction in serum chemerin and some inflammatory factors&#8217; levels. According to the results of the current study, previous studies showed that the use of LC leads to an increase in overall insulin sensitivity and whole body insulin-mediated glucose uptake in animals or humans with type 2 diabetes.<sup><xref ref-type="bibr" rid="B16">16</xref> , <xref ref-type="bibr" rid="B26">26</xref></sup> Considerable evidence supports the fact that fatty acid oversupply and obesity leads to an ectopic accumulation of several lipid metabolites in heart muscle and possibly other tissues, which are detrimental to insulin signaling and leads to insulin resistance.<sup><xref ref-type="bibr" rid="B27">27</xref></sup> Cardiac muscle cells cannot synthesize LC <italic>de novo</italic> and must acquire it exogenously via the carnitine/organic cation transporter 2.<sup><xref ref-type="bibr" rid="B28">28</xref></sup> Based on these finding we suggest that LC supplementation in the diet may restore the LC pool and reduce lipid metabolites and lipotoxicity in cardiac and adipose tissues.</p>
        <p>Based on our knowledge, the effects of LC on systemic chemerin level or its tissue expression in cardiac tissue of diabetic animals or humans have not been investigated so far. Our results, for the first time, show that protein and mRNA levels of chemerin and its receptor were reduced in the cardiac tissue of diabetic mice, concurrently with increased whole-body insulin sensitivity. Previous findings showed that chemerin mRNA and protein levels were elevated in the epicardial adipose tissue of patients with coronary artery disease.<sup><xref ref-type="bibr" rid="B29">29</xref></sup> Serum chemerin levels are also elevated in patients with coronary artery disease and correlated with the severity and extent of coronary stenosis and several cardiometabolic parameters.<sup><xref ref-type="bibr" rid="B30">30</xref></sup> It has been observed that chemerin increases apoptosis and caspase-9 activity in murine cardiomyocytes and improve the cardioprotective parameters in isolated perfused rat heart.<sup><xref ref-type="bibr" rid="B10">10</xref> , <xref ref-type="bibr" rid="B31">31</xref></sup> Chemerin treatment also alters the outcome of myoblast cells, from myogenesis to adipogenesis, which is characterized by increased ROS levels and TG content in treated cells.<sup><xref ref-type="bibr" rid="B32">32</xref></sup> Taken together, it was concluded that the reduction in chemerin levels and its receptor expression in cardiac tissue of diabetic mice after LC treatment may attenuate the adverse effect of chemerin on cardiomyocytes in diabetic animals. Further studies are needed to confirm this opinion.</p>
        <p>Although the results of the current study showed that LC treatment can attenuate the increase of chemerin expression in target tissues, the molecular mechanisms regulating its expression remain poorly understood. Our results showed that LC treatment can reduce the serum levels of TNF&#945; and IL1&#946; in obese, diabetic rats. It was observed that these proinflammatory cytokines induce chemerin mRNA expression and secretion from 3T3-L1 adipocytes.<sup><xref ref-type="bibr" rid="B33">33</xref></sup> Serum chemerin levels are also associated with serum levels of TNF&#945; in obese patients.<sup><xref ref-type="bibr" rid="B34">34</xref></sup> Based on these findings, the reduction in chemerin expression in diabetic mice may be due to a decrease in the secretion of inflammatory mediators. Hyperinsulinemia improvement may also be another mechanism caused by LC in reducing chemerin expression. Our results showed that LC could attenuate the increase in insulin levels in obese, diabetic mice. Because insulin can increase chemerin secretion from adipose tissue <italic>in vitro</italic> and in tissue explants,<sup><xref ref-type="bibr" rid="B35">35</xref></sup> we suggest that insulin reduction in LC-treated animals may have a regulatory role on chemerin expression in adipose and cardiac tissues of diabetic mice.</p>
        <p>There are some possible limitations to this study. In our study, gene expression was measured in total cardiac tissue in experimental animals. In light of the fact that various cardiac cell types, such as cardiomyocytes and cardiac fibroblasts, may have different actions on the pathogenesis of cardiac disease, our data did not allow differentiating expression profiles between the different cell types. Furthermore, differences in gene expression profiles between cardiac tissues from the right and left ventricles and atria have been confirmed, in addition to differences between cardiac cell types. Thus, we did not differentiate the gene expression between different parts of cardiac tissue in experimental animals. A further limitation is related to the fact that we measured all factors in young adult animals and within a short period of an experimental diabetes model. In this regard, it is of interest recalling that aging and long-term diabetes is by far the dominant risk factor for the development of cardiovascular diseases and the prevalence of cardiovascular diseases increases dramatically with increasing age. We did not determine whether LC treatment in aged rats or those with long-term diabetes leads to a similar downregulation of the expression of chemerin and its receptor in cardiac tissue of diabetic rats.</p>
      </sec>
      <sec sec-type="conclusions">
        <title>Conclusion</title>
        <p>In summary, our data showed that the consumption of a high-calorie diet resulted in obesity, insulin resistance and upregulation of chemerin and its receptor, CMKLRI, in adipose and cardiac tissues of mice. The treatment of diabetic mice with LC can attenuate symptoms of insulin resistance and suppress the overexpression of chemerin in diabetic animals. The results of the current experiment aid in the understanding of the novel regulatory effect of LC on cardiac gene expression in obesity and diabetes conditions. Further studies are needed to provide more evidence about nutrition therapy using LC for the non-pharmacological management of patients with diabetes and CVD based on the regulation of chemerin components in cardiac muscle.</p>
      </sec>
    </body>
    <back>
      <fn-group>
        <fn fn-type="other">
          <p>Study Association</p>
          <p>This article is part of the thesis of master submitted by Rezvan Amiri, from Shahid Chamran University of Ahvaz.</p>
        </fn>
      </fn-group>
      <fn-group>
        <fn fn-type="supported-by">
          <p>Sources of Funding: This study was partially funded by Shahid Chamran University of Ahvaz</p>
        </fn>
      </fn-group>
    </back>
  </sub-article>
</article>
