Oxidative and Nitrosative Stress and Progression of Diabetic Nephropathy in Type 2 Diabetes

Background: The role of nitric oxide (NO) is controversial in diabetes nephropathy progression and the mechanisms remain unknown, especially in non-obese type 2 diabetes. To examine mechanisms of nephropathy progression in nonobese type 2 diabetes, we used spontaneously diabetic Torii (SDT) rats, a newly established model of non-obese type 2 diabetes. Methods: Fourteen male Sprague-Dawley rats were used as a control (20 weeks, n = 6; 30 weeks, n = 8), and 20-week-old male SDT rats were divided into 2 groups: diabetic (DM, n = 8) and DM + insulin (n = 8) groups. Twenty-and 36-week-old rats were sacrificed, and blood, urine, and histomorphometric analyses, mRNA expression analysis of endothelial NO synthase (eNOS) and NADPH oxidase, and blood pressure measurement were performed. Results: At 36 weeks, NO metabolites, and 8-hydroxydeoxyguanosine (8-OHdG) were significantly higher in the diabetic group than in the other 2 groups. Further renal studies showed in creased glomerular volume and mesangial area, and intensified eNOS, 8-OHdG, and nitrotyrosine immunostaining in the diabetic group. Oxidative and nitrosative stress were positively associated with increased glomerular volume and mesangial area, which were mostly recovered by insulin therapy. Conclusions: NO and oxidative stress increased in SDT rats, suggesting that these play key roles in nephropathy progression in non-obese type 2 diabetes. Copyright (C) 2010 S. Karger AG, Basel