Regulação da adipogênese e da secreção de quemerina por ácidos graxos de cadeia média e pelo ácido graxo eicosapentaenóico em células 3T3-L1

• Ano de defesa: 2010
• Autor(a) principal: Costa, André Gustavo Vasconcelos
• Orientador(a): Bressan, Josefina
• Banca de defesa: Aliaga, Maria Jesus Moreno , Paula, Sérgio Oliveira de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Ciência e Tecnologia de Alimentos
• Departamento: Ciência de Alimentos; Tecnologia de Alimentos; Engenharia de Alimentos
• País: BR
• Palavras-chave em Português: Lipídios; Síndrome metabólica; Adipocinas
• Palavras-chave em Inglês: Lipids; Metabolic syndrome; Adipokines
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS
• Link de acesso: http://locus.ufv.br/handle/123456789/447

The incidence of obesity has been drastically increasing, reaching epidemic proportions worldwide, mainly in Western and industrialized countries. Scientific evidence relates obesity to a chronic inflammatory process of low intensity, due to increased pro-inflammatory cytokines, such as an abnormal production of tumor necrosis factor alpha (TNF&#945;). Hypertrophy and hyperplasia of adipocytes have been associated with diseases related to the metabolic syndrome, in which obesity seems to be the pivot. Therefore, the study of adipogenesis is crucial in the understanding of obesity, as well as its treatment. Studies suggest that both the eicosapentaenoic acid (EPA) and medium-chain fatty acids (MCFA) are capable of modulating the incorporation of lipids during the adipogenesis and of regulating the expression of key adipogenic transcription factors to cell differentiation. This study aimed to evaluate the effect of EPA and MCFA (C8:0 and C12:0) over the adipogenesis in 3T3-L1 cells. Moreover, the effect of such fatty acids over the mRNA expression and chemerin secretion, a new adipocyte involved in adipogenesis, was evaluated. Hence, preadipocytes were cultured in the presence (induced adipogenesis) or absence (spontaneous adipogenesis) of a hormonal cocktail. Throughout the differentiation process, cells were treated with C8:0 (250 &#956;M), C12:0 (250 &#956;M) and EPA (100 or 200 &#956;M), supplemented or not with TNF&#945;. During the experimental period, samples were collected in order to assess the gene expression of: preadipogenenic factor (DLK1), wingless related MMTV integration site 10b (WNT10b); CCAAT / enhancer-binding proteins (C/EBP) &#946;, &#948;, and &#945;; peroxisome proliferator-activated receptor gamma (PPAR&#947;) and chemerin. The incorporation of lipids was determined by Oil Red-O. Furthermore, still regarding the study of chemerin, mature adipocytes were incubated for 24 hours with the previously described fatty acids, along with TNF&#945; and insulin, in the presence or absence of protein kinases inhibitors. At the end of this period, an analysis of the mRNA expression and chemerin secretion was conducted. The results showed that during the induced adipogenesis, the fatty acids did not significantly alter the incorporation of lipids. On the other hand, during the spontaneous adipogenesis, EPA (200 &#956;M) promoted a greater incorporation of lipids (p<0.05), while the tested MCFA demonstrated no such effect. When added of TNF&#945;, the C8:0 decreased the incorporation of lipids during the induced adipogenesis, thus enhancing the inhibitory effect of this cytokine. When added of TNF&#945;, EPA stimulated the mRNA expression of the DLK1, WNT10b and C/EBP&#946;, whereas the C/EBP&#945; and PPAR&#947; expression were inhibited. The EPA did not present significant effects over the C/EBP&#948;. The MCFA were able to regulate the expression of the classical transcriptional adipogenic factors (C/EPB&#946;, &#945; and &#948; and PPAR&#947;), with particular emphasis given to the effects achieved by the C8:0. Regarding the expression of chemerin, it was observed that, apparently, the studied fatty acids did not participate in the secretion and expression of such adipokine. However, in a 24-hour incubation study, TNF&#945; stimulated the expression of the mRNA chemerin, as well as its secretion, possibly via phosphatidil inositol 3-kinase (PI3K). In conclusion, the results showed that the analyzed fatty acids are capable of modulating the incorporation of lipids, as well as the expression of key adipogenic transcription factors, thus potentializing the effect of the TNF&#945;.