The myocardial protective effects of puerarin on STZ-induced diabetic rats

To investigate the myocardial protective effects of puerarin on streptozotocin (STZ)-induced diabetic rats and the possible mechanism were involved. 45 Sprague-Dawley male rats were randomly divided into 3 groups as diabetic group (intraperitoneally injected STZ 65 mg/kg), puerarin treatment group (intraperitoneally injected STZ 65 mg/kg, and intraperitoneally injected puerarin 100 mg/kg/day for 4 weeks), and control group (intraperitoneally injected saline 6 ml/kg). Four weeks after the model induction, the myocardial changes were observed by H-E stain and Transmission electron microscopy, the alteration of thrombospondin-1 (TSP-1) protein and mRNA expression in the myocardium were also assessed by immunohistochemistry and real-time PCR. The heart function of three groups' rats was tested by Langendorff isolated in vivo heart perfusion. The differences in the data of weight and blood sugar of diabetic between puerarin treatment and normal groups were significant after 4 weeks (P<0.01). Our results demonstrated that diabetic myocardial ultrastructural changes included myofibrillar disarrangements and mitochondria disruption. These damages were significantly less severe in the puerarin treatment group compared with the diabetic group. A significant decrease of TSP-1 expression was observed in the puerarin treated rats' myocardium compared to the diabetic rats (P<0.01). Left ventricular systolic end pressure (LVSEP) and left ventricular developed pressure (LVDP) of puerarin treatment group were also significantly increased compared to diabetic group (P<0.01). Altogether puerarin could improve the left ventricular function of diabetic rats and showed protective effects of myocardium by decreasing the TSP-1 expression in myocardium of diabetic rats.