褪黑素及其受体激动剂对Mfn2介导的T2DM大鼠肝糖代谢基因的调节作用

Regulation Effects of Melatonin and Its Receptor Agonist on Liver Glucose Metabolism Gene Mediated by Mfn2 in T2DM Rats

目的研究褪黑素及其受体激动剂Neu-p11对线粒体融合蛋白2(Mfn2)介导2型糖尿病(T2DM)大鼠肝糖代谢关键基因的调节作用。方法采用长期高脂肪饲养加小剂量链脲佐菌素诱导雌性大鼠T2DM动物模型,分为模型组、褪黑素组和Neu-p11低、高剂量组,同时增加正常大鼠为正常对照组,灌胃给药4周。测定大鼠空腹血糖(FBG)、胰岛素(INS),计算胰岛素抵抗指数(HOMA-IR)和胰岛素敏感指数(ISI),并进行腹腔葡萄糖耐量试验。采用RT-PCR方法测定肝脏Mfn2及葡萄糖激酶(GK)、磷酸烯醇式丙酮酸羧激酶(PEPCK)、葡糖糖-6-磷酸酶(G-6-P)、糖原合成激酶-3β(GSK-3β)的mRNA表达量。观察肝脏组织病理形态变化。结果 4组T2DM大鼠不同时间点FBG水平显著高于正常对照组,INS和HOMA-IR水平高于正常对照组,ISI水平低于正常对照组,PEPCK、G-6-P、GK、GSK-3β和Mfn2 mRNA表达水平与正常对照组比较差异均有统计学意义(P<0.01)。给药4周后,Neu-p11低剂量组FBG、INS和HOMA-IR水平低于模型组(P<0.05)。褪黑素组和Neu-p11低、高剂量组Mfn2 mRNA表达水平以及Neu-p11低剂量组GK mRNA表达水平均高于模型组(P<0.05,P<0.01)。褪黑素组和Neu-p11低、高剂量组G-6-P mRNA表达水平以及Neu-p11低、高剂量组PEPCK mRNA表达水平均低于模型组(P<0.05,P<0.01)。褪黑素组和Neu-p11低、高剂量组明显改善了T2DM大鼠肝脏的组织形态,Neu-p11低剂量组改善效果显著。结论 Neu-p11可改善由Mfn2介导的T2DM大鼠的胰岛素抵抗、糖代谢异常及肝糖代谢酶mRNA异常表达,达到保护肝脏,治疗糖尿病的作用。

Objective To study regulation effects of melatonin and its receptor agonist on liver glucose metabolism gene mediated by Mfn2 in type 2 diabetes mellitus(T2DM)rats.Methods Models of T2DM female rats had been fed with high-fat feeding and induced by long-term small dose Streptozotocin,and then the rats were divided into model group,melatonin group and Neu-p11 low and high dose groups,and other normal rats were recruited as control group,and intragastric administration was continued for 4 weeks.Fasting plasma glucose(FBG)and insulin(INS)were detected,and homeostasis model of assessment-insulin resistance(HOMA-IR)and insulin sensitivity index(ISI)values were calculated,and celiac glucose tolerance test was also performed.Reverse transcription-polymerase chain reaction(RT-PCR)was used to detect mRNA expressions of hepatic Mfn2 and glucokinase(GK),phosphoenolpyruvate carboxykinase(PEPCK),glucose-6-phosphate(G-6-P),glycogen synthase kinase-3β(GSK-3β).Histopathologic changes of liver tissues were observed.Results In four T2DM model groups,FBG levels were significantly higher at different time points,and INS and HOMA-IR levels were significantly higher,while ISI levels were significantly lower than those in control group,and there were significant differences in PEPCK,G-6-P,GK,GSK-3βand Mfn2 mRNA expressions between four T2DM model groups and control group(P<0.01).After 4 weeks of drug therapy,FBG,INS and HOMA-IR levels in Neu-p11 low dose group were significantly lower than those in model group(P<0.05).Mfn2 mRNA expressions in melatonin group and Neu-p11 low and high dose groups,and GK mRNA expression in Neu-p11 low dose group were significantly higher than those in model group(P<0.05,P<0.01).G-6-P mRNA expressions in melatonin and Neu-p11 low and high dose groups,and PEPCK mRNA expressions in Neu-p11 low and high dose groups were significantly lower than those in model group(P<0.05,P<0.01).Liver tissue morphologies of T2DM rats in melatonin and Neu-p11 low and high dose groups were significantly improved,and the improvement in Neu-p11 low dose group was more significant.Conclusion Neu-p11 can improve insulin resistance,glucose metabolism abnormality and abnormal mRNA expression of hepatic glucose metabolism enzyme mediated by Mfn2 in T2DM rats in order to protect liver and treat diabetes mellitus.