2型糖尿病合并非酒精性脂肪肝大鼠肝脏SIRT1、UCP2表达的变化

Hepatic SIRT1 and UCP2 expressions in rats with type 2 diabetes mellitus and nonalcoholic fatty liver

目的观察2型糖尿病(T2DM)合并非酒精性脂肪肝(NAFLD)大鼠肝脏沉默调节蛋白1(SIRT1)、线粒体脱偶连蛋白2(UCP2)表达的情况,探讨T2DM合并NAFLD的可能发病机制。方法雄性SD大鼠24只,随机分为正常对照组(NC组,12只)和T2DM合并NAFLD模型组(MC组,12只)。NC组喂以常规饲料,MC组喂以高脂高糖饲料。12周末隔夜空腹给予MC组大鼠腹腔注射链脲佐菌素(30 mg/kg)1次,破坏部分胰岛,NC组注射相应体积的柠檬酸缓冲液。14周末测定两组大鼠体质量、空腹血糖、谷丙转氨酶、谷草转氨酶、总胆固醇、甘油三酯、高密度脂蛋白、低密度脂蛋白、极低密度脂蛋白、游离脂肪酸、空腹胰岛素、计算胰岛素抵抗指数,并观察肝脏组织的病理变化,免疫组化法及Real-time PCR法测定肝脏组织中SIRT1、UCP2的表达情况。结果 14周时MC组大鼠空腹血糖、谷丙转氨酶、谷草转氨酶、总胆固醇、甘油三酯、低密度脂蛋白、极低密度脂蛋白、游离脂肪酸、空腹胰岛素、计算胰岛素抵抗指数均较NC组大鼠升高(P<0.05),高密度脂蛋白较NC组减低(P<0.05)。病理组织学结果表明NC组大鼠肝组织结构完整,肝细胞排列紧密成肝索,细胞质丰富,细胞核圆形;MC组大鼠肝细胞高度气球样变,胞质中有大量脂滴空泡,肝组织均可见中至重度脂肪肝。在免疫组化和mRNA水平上表明,MC组肝脏SIRT1表达较NC组明显降低(P<0.05),而UCP2表达较NC组明显升高(P<0.05)。结论在T2DM合并NAFLD大鼠肝脏组织中SIRT1表达显著降低,UCP2表达显著升高。

Objective To 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.Methods Twenty-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.Results At 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（P0.05）.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（P0.05）.Conclusion The expression of SIRT1 is significantly lowered and UCP2 increased in the liver of rats with T2DM and NAFLD.