Rhein improves insulin sensitivity of diabetic rats by increasing the protein expression levels of PPAR-γ and GluT-4 in adipose tissue

Objective To investigate the mechanism for rhein to improve the insulin sensitivity in diabetes mellitus. Methods Male Wistar rats were randomly divided into normal control group (NC,n=15) and diabetic group (DM,n=40) induced by STZ and high-fat diet.Diabetic rats were randomly divided into diabetic control group (DM-C,n=15) and diabetic group treated with rhein (DM-T,n=15).Then DM-T group was given intragastric administration with rhein at the dose of 100 mg/ (kg-1·d-1) for 11 weeks.FBG,fasting serum insulin (FIns),triglyceride (TG),total cholesterol (TC),insulin sensitivity index (ISI) and other biochemical parameters in each group were measured.The protein expressions of PPAR-γ and GluT-4 were determined by immunohistochemistry and Western blot. Results At the end of the 17th week,compared with NC group,DM-C group showed higher FBG and TG,lower ISI,lower protein expressions of PPAR-γ and GluT-4 in the adipose tissue.Compared with DM-C group,DM-T group showed lower FBG [(15.73±3.08 vs 22.57±3.23) mmol/l,P0.01],higher ISI (-4.97±0.29 vs -5.46±0.61,P0.05).Integrated optical density (IOD) showed higher protein expression of PPAR-γ of DM-T group in adipose tissue as compared with DM-C group [13613.35 (7293.85~17198.73) vs 4750.70 (3346.63~10390.63),P0.01].Integrated density (ID) showed higher protein expression of GluT-4 of DM-T group in adipose tissue as compared with DM-C group [1.157 (0.921~1.953) vs 0.828 (0.621~1.010),P0.01]. Conclusions Rhein increases the protein expressions of PPAR-γ and GluT-4 in adipose tissue,decreases FBG and improves insulin sensitivity of diabetic rats.