Estudo do músculo esquelético de camundongos C57BL/6 com síndrome metabólica

• Autor(a) principal: Carvalho, Manoela Lopes
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/7877
• topic: Muscle; Skeletal; Metabolic syndrome; Diet; High-fat; Músculo esquelético; Síndrome metabólica; Dieta hiperlipídica; Músculo esquelético; Síndrome metabólica; Dieta hiperlipídica; CNPQ::CIENCIAS BIOLOGICAS::MORFOLOGIA

Metabolic syndrome is a collection of cardiometabolic risk factors that includes obesity, insulin resistance, hypertension and dyslipidemia. A high-fat diet causes body mass gain and potentially increase other risk factors associated with metabolic syndrome in C57BL/6 mice. The lipid accumulation in non-adipose cells can cause cell dysfunction or cell death via apoptosis, and these processes have been broadly defined as lipotoxicity. In order to examine the possible effects of a high-fat diet in the skeletal muscle morphology, twenty male C57BL/6 mice at 13 weeks of age were allocated to feed one of the two diets during 16 weeks: high-fat chow (HF group, 60% calories from fat) or b) standard chow diet (SC group, 10% calories from fat. The mice were sacrificed blood samples were obtained by cardiac puncture for biochemistry analyzes. The results showed that plasma TC and TG were higher in HF group than SC group. No difference was found to FG between the groups, but FI was higher in HF animals in comparison to SC ones. The HF animals also showed higher HOMA-IR than SC animals and the HF group had major BM gain. In order to analyze the skeletal muscle ultrastructure, the mice gastrocnemius muscles were dissected and samples were fixed with 2.5% glutaraldehyde and ultrathin n sections were examined in a 906 Zeiss transmission electron microscope. In order to realize the lipid droplet quantification, muscle samples were fixed with 2.5% glutaraldehyde, washed Imidazol buffer and three Epon blocks of each mouse were randomly selected and the grids were observed using a transmission electron microscope (EM 906 Zeiss). Transmission electron microscopy revealed changes in the skeletal muscle ultrastructure of the HF group, as enhancement of the lipid droplets deposition and large and altered intermyofibrillar mitochondria. Lipid droplet quantification revealed elevated intramyocellular lipids deposition in HF group compared with SC group (P< 0.0001). Muscle sections obtained of both experimental groups were also immunolabeled with anti-mouse SERCA1 (sarco/endoplasmic reticulum Ca2+ ATPase) primary antibody and the confocal microscopy revealed an increased expression of SERCA1 in skeletal muscle fibers HF group when compared with the SC group. Therefore, the results indicate that a HF diet influence the ultrastructure of muscle fibers, increasing the number of lipid droplets, changing the mitochondrial morphology and increasing the expression of SERCA1. In addition promotes the development of a collection of metabolic disorders, characterizing the typical metabolic syndrome shape.