Effects Of Globular Adiponectin On Insulin Secretion And The Expression Of IR And IRS-1in Diabetic Rats

Objective To investigate the influence of globular adiponectin （gAd） on insulinsecretion and the expression of IR （insulin receptor） and IRS^-1(insulin receptorsubstrate^-1) in HFD/STZ induced diabetic rats.Methods Male Wistar rats were randomly divided into normal control group （NCgroup） and diabetic model group. Type2diabetic rats were induced by high-fat dietand low-dose STZ （28mg/kg） intraperitoneal injection. Then the diabetic model ratswere further randomly divided into type2diabetic control rats （T2DM group） andtype2diabetic rats treated with gAd （gAd group）. Rats of gAd group wereintraperitoneally injected with3.5μg· kg^-1· d^-1gAd for7days, while Rats of NCgroup and T2DM group received0.9%saline instead. The concentrations of bloodglucose, fasting serum insulin, cholesterol （TC）, triglyceride （TG）, low densitylipoprotein （LDL-C）, and high density lipoprotein （HDL-C） were measured. IR andIRS^-1 protein expression were examined by western blotting andimmunohistochemistry. IR and IRS^-1 mRNA expression in liver and skeletal muscletissue were analyzed by Quantitative Real-Time RT-PCR.Results （1） Serum blood glucose, cholesterol, triglyceride, and low densitylipoprotein of gAd-treated group decreased than those of T2DM group, while fastingserum insulin of gAd-treated group increased than that of T2DM group.（2） IR proteinand mRNA expression in hepatic and skeletal muscle tissues of T2DM rats increasedcompared to those of NC group.（3） Treatment with gAd reduced the expression of IRprotein in hepatic and skeletal muscle tissues of diabetic rats, and it down-regulatedIR mRNA expression in hepatic tissue.（4） Hepatic IRS^-1 protein and mRNAexpression of T2DM rats increased than those of NC group, but no statisticaldifference was found in skeletal muscle tissue between the two groups.（5）GAd-treatment had no impact on IRS^-1 protein expression in hepatic and skeletal muscle tissues of diabetic rats.Conclusion Globular adiponectin exerts its beneficial effects on type2diabetic ratsthrough mediating dyslipidemia, promoting insulin secretion, and regulating IRexpression in hepatic and skeletal muscle tissues.