Change in the lipid profile, lipogenic and related enzymes in the livers of experimental diabetic rats: effect of insulin and vanadate

Administration of sodium orthovanadate to diabetic animals exhibits insulin-like effects and has been effective in the reversal of biochemical complications. This study evaluates the effect of sodium orthovanadate (0.6 mg/ml) treatment for 21 days on the hepatic glucose homeostasis and lipid metabolism in alloxan diabetic rats. The activities of two lipogenic enzymes, glucose-6-phosphate dehydrogenase and malic enzyme; and related enzymes, hexokinase and glucose-6-phosphatase were measured in the liver cytosolic fractions of diabetic rats and diabetic rats treated separately with insulin and sodium orthovanadate. The total lipids, triglycerides and cholesterol levels were estimated in the livers of the diabetic and the treated rats. The activities of both the lipogenic enzymes and hexokinase isozymes were significantly decreased, whereas the activity of glucose-6-phosphatase was significantly increased in the diabetic liver. During diabetes, the levels of total lipids and triglycerides increased significantly with a decrease in the cholesterol levels in the liver. Insulin and vanadate were able to restore the altered enzyme activities to almost control levels. Both insulin and vanadate were found to partially restore the altered levels of total lipids, triglycerides and cholesterol in the livers of diabetic rats. The results indicate that vanadate administration to diabetic animals normalizes blood glucose and causes marked improvement of altered lipid metabolism during diabetes. The present study and earlier reports suggest the possible use of vanadate as insulin replacement in the therapy of diabetes when administered at pharmacological doses. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.