Effect of Vitamin E on Diabetic Nephropathy in Streptozotocin-Induced Diabetic Rats

Diabetic nephropathy (DN) is a serious complication of diabetes mellitus; oxidative stress plays a key role in the pathogenesis of DN. The objective of this study was to evaluate the antioxidant effect of vitamin E on diabetic nephropathy. A control group and three groups of rats with streptozotocin-induced diabetes mellitus (untreated diabetic rats and diabetic rats treated with vitamin E 250 and 500 mg/kg) were studied. After 4 weeks of treatment, the kidneys were removed under anesthesia with sodium pentobarbital. The kidneys were weighed, the AT₁ and AT₂ receptor expression was measured by Western blot, and the activities of glutathione peroxidase, catalase, and superoxide dismutase were determined in the renal cortex. Rats with diabetes mellitus had hyperglycemia, increased food and water consumption, and higher urinary volume than control rats. In diabetic rats (DM), kidney hypertrophy was observed and measured by kidney weight, protein/DNA ratio in the renal cortex, and proximal tubular cell area; proteinuria and reduced creatinine clearance were observed. AT₁ and AT₂ receptor expression in the kidney cortex of DM rats increased significantly compared to normoglycemic rats; antioxidant enzyme activities were decreased; treatment with vitamin E reversed kidney hypertrophy and reduced proteinuria; reduction in expression of AT₁ and AT₂ receptors was associated with increased antioxidant activity. Thus, treatment with vitamin E slows the progress of DN.