Effects of grape seed proanthocyanidin extract on oxidative stress induced by diabetes in rat kidney.

Background: This study examined the effect of grape seed proanthocyanidin extract (GSPE) on lipid peroxidation content and activity of tissue antioxidant enzymes, including catalase, superoxide dismutase and glutathione peroxidase in diabetic rats.

Methods: Thirty male rats were divided into three groups of 10 rats each: control, diabetic and diabetic groups that received 500 mg/kg GSPE for 6 weeks. Diabetes was induced by a single intraperitoneal injection of streptozotocin (50 mg/kg body weight). Rats with fasting blood glucose levels above 250 mg/dl were used as diabetic animals. The first 24-hour urinary albumin excretion (UAE) was measured two weeks after diabetes induction and then each week until the end of the experimental period in all groups. Lipid peroxidation content and activities of catalase, superoxide dismutase and glutathione peroxidase were measured in kidney homogenate supernatants. Statistical significance of differences was assessed with one-way ANOVA by SPSS followed by Tukey's t-test. P < 0.05 was assumed statistically significant.

Results: UAE in diabetic nephropathy rats were significantly higher than in control. In addition, an increase in lipid peroxidation content and decrease in catalase, superoxide dismutase and glutathione peroxidase activities in kidney of diabetic nephropathy rats were observed. The GSPE administration did not affect on body weight, but significantly decreased lipid peroxidation and augmented the activities of antioxidant enzymes studied in kidney of diabetic nephropathy rats as well as reduced UAE and decreased kidney weight.

Conclusion: The results suggested that GSPE could ameliorate diabetic nephropathy rats through reduction of oxidative stress and increase in renal antioxidant enzyme activity.