Effect of Pioglitazone on Expression of AdipoR1 in Skeletal Muscle of Type 2 Diabetic Rats

Aim To investigate the effects of pioglitazone on the expression of skeletal muscle AdipoR1 in type 2 diabetic rats,and explore the improvement effect and its mechanisms of pioglitazone on type 2 diabetes and insulin resistance.Methods Forty healthy eight-week-old female Sprague Dawley(SD) rats were randomly divided into normal control group(n=10),diabetic group(n=15),and pioglitazone group(n=15).Type 2 diabetes rat model was reproduced by feeding a high-sugar-fat diet followed by an intraperitoneal injection of a low dose of streptozotocin(STZ).Rats in pioglitazone group were laraged with pioglitazone 10 mg/(kg·d),while those in control group and diabetic group received the same amount of normal saline for 12 weeks.After 3 months,blood was taken from femoral vein and serum adiponectin was measured by enzyme-linked immunosorbent assay(ELISA).The structure of skeletal muscle was observed with light microscope and electron microscope.The protein expression of AdipoR1 in skeletal muscle was detected by immunohistochemical staining.Results Serum adiponectin(1.01±0.27 mg/L) in T2DM group was significantly decreased compared with normal control group(1.73±0.32 mg/L),but that of pioglitazone group(1.34±0.43 mg/L) was significantly increased compared with T2DM group(P0.05).Immunohistochemical staining showed that the expression of AdipoR1 in skeletal muscle was the most obvious in normal control group and was attenuated in T2DM group.The expression of AdipoR1 in skeletal muscle of pioglitazone group was more significant than that in T2DM group,but was weaker than that in normal control group.Light microscope and electron microscope showed no obvious abnormalities in skeletal muscle structure.Conclusions The levels of serum adiponectin and AdipoR1 in skeletal muscle decline in type 2 dia-betic rats.Pioglitazone can up-regulate the levels of serum adiponectin and AdipoR1 in skeletal muscle thus it can down-regulate the circulating levels of glucose and lipids and improve insulin sensitivity.