Avaliação das alterações morfo-funcionais hepáticas e do balanço redox em um modelo murino para a síndrome metabólica induzida por uma dieta hipercalórica

Abstract

The non-alcoholic fat liver diseases (NAFLD) have been presented, recently, as a novel component of the Metabolic Syndrome (MetS), representing the oxidative stress a critical role in their progression. In this context, the present study aimed to assess the morphofunctional hepatic alterations and the redox balance in a murine model for the MetS induced by a high calorie diet, after treatment with tempol and apocinina. C57Bl/6 male mice, young (6-8 weeks) and elderly (53-57 weeks), were divided in four groups: control group (CT; “n” young=8 and “n” elderly=5), fed with “chow” diet (14% calories from lipids); DHC group (“n” young=9 and “n” elderly=5), receiving hypercaloric diet for 14 weeks (58,4% calories from lipids); DHC + Tempol group (“n” young=4 and “n” elderly=9), which received hypercaloric diet and treatment with tempol (50mg/kg) in the water for drinking; DHC + Apocinin group (“n” young=4 and “n” elderly=9), fed with a hypercaloric diet and under apocinin treatment (50mg/kg) in the water for drinking. Metabolic and the redox state assessment, as well as the histological analyses were performed. After the end of the experimental period, young DHC animals were not shown to present significant weight gain, being the latter observed in the elderly DHC animals, when compared to CT group. The treatment with tempol and apocinin was not effective in modifying this parameter in both groups. The DHC animals, both young and elderly, showed fasting hyperglicaemia, and the treatment with tempol and apocinin did not change this profile. A significant improvement in the glucose tolerance was observed in the young animals after the treatment with apocinin, but the treatment with tempol failed to show so. In the elderly animals, a significant improvement in the glucose tolerance and insulin sensitivity was identified after the treatment with tempol and apocinin. An elevated accumulation of visceral fat was identified in the DHC animals (young and elderly), so that the treatment with tempol and apocinin did not alter this profile. An elevated serum concentration of total cholesterol was shown in the young and elderly DHC animals when compared to the CT group, the same not happening to triglycerides, VLDL and lipid peroxidation in both groups, young and elderly. The pharmacological treatment was not shown to be effective in altering these serum parameters. In the young DHC animals, it was not observed significant changes in the enzymatic activities of the AST and ALT, as well as AST/ALT ratio, ALP, γ-GT, LDH, albumin and total proteins, when compared to the CT group. However, in the DHC elderly animals, and increased AST activity and AST/ALT ratio were observed among these parameters of hepatic assessment. The DHC animals, young and elderly, presented elevated lipid peroxidation and fat liver accumulation, with numerous fat vacuoles at histology. The pharmacological treatment with tempol and apocinin ameliorated, in a qualitative manner, the fat accumulation in the liver, both in the young and elderly animals, without, however, modifying the hepatic lipid peroxidation. Furthermore, the DHC elderly animals presented high hepatic levels of total lipids, triglycerides, total cholesterol and VLDL cholesterol, with a similar condition not being observed in the DHC young animals. The hepatic activity of the antioxidant enzymes (SOD and CAT) was not shown to be significantly different after the dietary and pharmacological treatments. An increase in the NADPH oxidase activity, and consequently the increased production of superoxide anion (•O2 -), may be involved in the mechanisms associated to the MetS and the NAFLD.