Experimental study of oxidative stress in the kidneys of diabetic rats

Objective To observe changes of oxidative stress in kidneys and their roles in diabetic nephropathy of rats. Methods Diabetic rats were induced by streptozocin (STZ). 36 rats were randomly divided into normal control group (NC group), DⅠgroup〔given protamine zinc insulin (PZI) 2~4 U/2 days〕 and DⅡgroup (given PZI 9~12 U·kg~-1 ·d~-1 ). 12 weeks later, blood glucose, blood cholesterol, trigalloyl glycerol (TG), urea nitrogen, creatinine, HbA1c, urinary creatinine, and urinary protein for 24 hours were measured. The activities of antioxidant enzymes in renal cortex, including total superoxide dismutase (TSOD), Cu-Zn SOD, Mn SOD, catalase (CAT), glutathione peroxidase (GSH-Px), and maleic dialdehyde (MDA) were measured by chromatometry. Results There was no significant difference in all indexes between NC and DⅡgroups. Compared with the other groups, the levels of blood glucose, cholesterol, TG, HbA1c in DⅠgroup increased significantly, the activities of TSOD, Cu-Zn SOD, CAT decreased significantly, but the activity of GSH-Px increased significantly. There was no significant difference in the activities of Mn SOD among three groups. The level of MDA in DⅠgroup was much higher than that in NC or DⅡgroup. Urinary protein in DⅠgroup was significantly higher than that in the other two groups, while creatinine clearance rates decreased significantly. Conclusions Diabetes could cause increase of oxidative stress in kidney of diabetic rats, which play an important role in pathogenesis of diabetic nephropathy.