RENAL CORTICAL EXPRESSION OF MESSENGER-RNAS FOR ANTIOXIDANT ENZYMES IN NORMAL AND DIABETIC RATS

Increased oxidative stress has been implicated in the development of v ascular complications of diabetes. In this study, we examined the hypo thesis whether chronic hyperglycemia induces oxidative stress by lower ing renal espression and activity of antioxidant enzymes and a decreas e in glutathione, an antioxidant, in streptozotocin diabetic rats. The results show that the expression of mRNAs for Cu/Zn superoxide dismut ase and glutathione peroxidase was significantly increased and that of catalase was decreased in diabetic rats. However, the superoxide dism utase activity was significantly lower in diabetic than normal glomeru li, whereas the activities of the other two enzymes correlated with th eir mRNA expression. Total glutathione content was significantly decre ased in diabetic compared to normal glomeruli. The data suggest that h yperglycemia induces oxidative stress by over-expressing rather than l owering certain antioxidant enzyme mRNAs in the kidney of diabetic rat s. Enhanced nonenzymatic glycation of enzyme protein seems to be the c ause for the observed decrease in glomerular superoxide dismutase acti vity. (C) 1997 Academic Press.