TIME-COURSE STUDY OF OXIDATIVE STRESS IN AORTA AND HEART OF DIABETIC RAT

1. Oxygen free radicals have been suggested to be a contributory facto r in complications of diabetes mellitus. In the present study, we inve stigated the lipid peroxide level [thiobarbituric acid-reactive substa nces (TBARS)] and activities of antioxidant enzymes (superoxide dismut ase, catalase and glutathione peroxidase) in aorta, heart and blood of control and streptozotocin-induced diabetic rats at various stages of development of diabetes (0 to 6 weeks). 2. There was no change in the TBARS levels of aorta, heart and blood in the control group, A signif icant (P<0.05) increase in TBARS levels of aorta, heart and blood was observed in the diabetic group. 3. There were no significant changes i n the activities of superoxide dismutase, catalase and glutathione per oxidase in the aorta, heart and blood of control rats at all time inte rvals. In the diabetic group, there was a significant (P<0.05) increas e in the activity of superoxide dismutase and glutathione peroxidase i n aorta from the fourth week onwards while the activity of catalase in creased at all time intervals, In the heart of diabetic rats, the acti vity of total superoxide dismutase and Cu-Zn-superoxide dismutase incr eased significantly (P<0.05) from the second week onwards while activi ty of Mn-superoxide dismutase decreased at the fourth week and increas ed at the sixth week. The activity of catalase and glutathione peroxid ase increased significantly (P<0.05) at all time intervals. In the blo od, the activity of superoxide dismutase and glutathione peroxidase in creased from the third week while catalase activity increased from the fourth week. 4. The present findings suggest that oxidative stress st arts at early onset of diabetes mellitus and increases progressively.