OBJECTIVETo observe the expression of SIRT1 and mitochondrial uncoupling protein 2 (UCP2) in the liver of rats with type 2 diabetes mellitus (T2DM) and nonalcoholic fatty liver (NAFLD) and explore the possible pathogenesis of T2DM and NAFLD.

METHODSTwenty-four male SD rat were randomized equally into control group and T2DM and NAFLD group (MC group), fed with standard diet and high-fat and high-sugar diet, respectively. At 12 weeks, the rats in MC group received a single dose of STZ (30 mg/kg) injected into the abdominal cavity for pancreatic islet destruction, and those in the control group received an equivalent volume of citric acid buffer. At 14 weeks, the body weight, FBG, hepatic function, blood lipid levels, FFAs, FINs and HOMA-IR of the rats were measured, and the liver pathology was examined with HE staining. The expression of SIRT1 and UCP2 in the rat liver was detected by immunohistochemistry and real-time quantitative PCR.

RESULTSAt 14 weeks, FBG, ALT, AST, TC, TG, LDL-C, VLDL, FFAs, FINs and HOMA-IR were significantly higher and HDL-C was significantly lower in MC group than in the control group (P<0.05). Pathological examination showed good structural integrity of the liver in the control group, and the liver cells were closely arranged with rich cytoplasm and round cell nuclei; in MC group, moderate to severe fatty liver was detected, and the liver cells showed severe ballooning degeneration and contained lipid vacuoles in the cytoplasm. The expression of SIRT1 was significantly lower and UCP2 significantly higher in MC group than in the control group (P<0.05).

CONCLUSIONThe expression of SIRT1 is significantly lowered and UCP2 increased in the liver of rats with T2DM and NAFLD.