RESUMO
Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis, insulin resistance and inflammation; however, the exact pathogenesis of NAFLD is not fully understood. Green tea polyphenols (GTP) exhibit beneficial effects against metabolic syndrome. However, the effect of GTP on NAFLD remains largely unknown. The aim of the present study was to investigate the effects of GTP on NAFLD in highfat diet (HFD)induced rats. The NAFLD rat model was induced with a HFD for 8 weeks. A total of 30 adult male Sprague Dawley rats were randomly divided into three groups: i) Normal control group; ii) HFD group; and iii) HFD with GTP group. Hematoxylin and eosin and Oil Red O analyses were performed. The levels of alanine aminotransferase (ALT), aspartate amino-transferase (AST) and inflammatory cytokines in the serum, as well as oxidative stress markers and hepatic lipids in the liver were measured. In addition, parameters associated with glucose metabolism were also assessed. Western blotting and RTqPCR were used to determine the expression levels of 5' adenosine monophosphateactivated protein kinase (AMPK). HFDinduced rats exhibited features associated with NAFLD. GTP intervention significantly reduced serum ALT and AST levels. Fasting serum glucose, insulin resistance and hepatic lipid levels were all decreased in the GTPtreated rats. GTP also significantly decreased the levels of TNFα, IL6 and malondialdehyde. In contrast, superoxide dismutase levels were increased in the liver. Furthermore, GTP also significantly increased phosphorylation of AMPK and attenuated histopathological changes indicative of injury in liver tissue. GTP has a protective effect on HFDinduced hepatic steatosis, insulin resistance and inflammation, and the underlying mechanism may involve the AMPK pathway.
