Effect of insulin and oral glutathione on glutathione levels and superoxide dismutase activities in organs of rats with streptozocin-induced diabetes.

The effect of insulin or glutathione treatment on glutathione content of liver and jejunal mucosa and on superoxide dismutase (SOD) activity of liver, kidney, and erythrocytes was investigated in pair-fed animals with streptozocin (STZ)-induced diabetes. Diabetes lowered hepatic glutathione concentration, but glutathione concentration of the jejunal mucosa was not affected. Insulin, but not oral glutathione, restored hepatic glutathione concentration to normal levels. Diabetes depressed activity of the cytosolic form of SOD in liver, kidney, and erythrocyte. Treatment of diabetic rats with oral glutathione or intramuscular insulin increased cytosolic SOD activity of renal cortex and liver (but not erythrocytes) to control levels. These results suggest a link between glutathione metabolism and cytosolic SOD activity in diabetes.