降糖增效方对糖尿病大鼠肝脏胰岛素信号通路IRS1位点磷酸化的影响

Effects of Jiangtang Zengxiao Fang on Phosphorylation of IRS1 in Diabetic Rats

目的通过观察降糖增效方对糖尿病大鼠肝脏胰岛素受体底物1(insulin receptor substrates 1,IRS1)磷酸化的影响来探讨该方发挥降糖增效作用的机制。方法将40只6~8周龄雄性ZDF(fa/fa)大鼠随机分为模型组、二甲双胍组(0.134 g/kg)、降糖增效方组(0.64 g/kg)、联合组(降糖增效方0.64 g/kg+二甲双胍0.134 g/kg),另选ZDF(fa/+)大鼠10只为正常组,连续干预6周;实验结束检测体空腹血糖(fasting blood glucose,FBG)、血清胰岛素水平(fasting insulin,FINS)、胰岛素抵抗指数(homeostatic model assessment of insulin resistance,HOMA-IR)、天门冬氨酸氨基转移酶(aspartate aminotransferase,AST)、血肌酐(serum creatinine,Scr)、尿素氮(blood urea nitrogen,BUN)、口服葡萄糖耐量试验(oral glucose tolerance test,OGTT);蛋白免疫印迹法(Western bloting)检测IRS1丝氨酸磷酸化位点ser307、ser612、ser1101表达。结果与模型组相比较,各治疗组大鼠FBG、FIns、HOMA-IR、OGTT2 h血糖水平、AUC、SCr、BUN显著降低(P<0.05,P<0.01);肝组织p-IRS1 Ser307、p-IRS1 ser612、p-IRS1 ser1101蛋白表达显著降低(P<0.05,P<0.01);与二甲双胍、降糖增效方组比较,联合组大鼠FBG、FIns、HOMA-IR显著降低(P<0.05,P<0.01);OGTT2 h血糖水平以及AUC显著降低(P<0.05,P<0.01);肝组织p-IRS1 Ser307、p-IRS1 ser612、p-IRS1 Ser1101蛋白表达显著降低(P<0.05,P<0.01)。结论降糖增效方降低糖尿病大鼠肝脏IRS1 ser307/612/1101位点磷酸化水平,这可能是其增加降糖疗效的机制。

Objective To observe effects of Jiangtang Zengxiao Fang(JZF)on phosphorylation of insulin receptor substrates 1(IRS1)in diabetic rats,and to investigate the mechanism of synergism of reducing blood glucose.Methods A total of 406-8 week male ZDF(fa/fa)rats were randomly divided into a model group,a metformin group(0.134 g/kg),a JZF group(0.64 g/kg),and a combination group(JZF 064 g/kg+metformin 0.134 g/kg).Another 10 ZDF(fa/+)rats were set as a normal group.The rats were continuously intervened for 6 weeks.Fasting blood glucose(FBG),fasting insulin(Fins),homeostasis model assessment-Insulin resistance(HOMA-IR),aspartate aminotransferase(AST),serum creatinine(Scr),blood urea nitrogen(BUN)and oral glucose tolerance test(OGTT)were detected after experiment.Western blot was used to detect the expression of ser307,ser612,ser1101 in phosphorylation of IRS1 in liver.Results Compared with the model group,FBG,Fins,HOMA-IR,Blood glucose level of 2 h in OGTT,AUC,AST,Scr and BUN in each group were decreased significantly(P<0.05,P<0.01).p-IRS1 ser307,p-IRS1 ser612,pIRS1 ser1101 protein expression level in the liver tissue were decreased significantly(P<0.05,P<0.01).Compared with JZF group and metformin group,FBG,Fins and HOMA-IR of the combination group were decreased significantly(P<0.05,P<0.01).Blood glucose level and AUC were significantly decreased at 2 h in OGTT(P<0.05,P<0.01).p-IRS1 ser307,p-IRS1 ser612,p-IRS1 ser1101 protein expression level in the liver tissue were significantly decreased(P<0.05,P<0.01).Conclusion JZF can regulate p-IRS1 ser307,p-IRS1 ser612,p-IRS1 ser1101 expression in liver tissue of diabetic rats,which might be the mechanism of improving the efficacy of reducing blood glucose.