Role of lipoic acid on insulin resistance and leptin in experimentally diabetic rats

Objective: We aimed to examine the changes in serum insulin and leptin levels in induced type I diabetes mellitus in relationship to glycemic state and lipid profiles and to clarify the role of lipoic acid (LA). Methods: Ninety-six male rats were equally divided into the following: a control group (normal, nondiabetic), a diabetic group induced by subcutaneous injection of alloxan (non-LA-treated), and an LA-treated diabetic group (for 4 weeks). Body weight, serum lipid profile, glucose, insulin, homeostasis model assessment insulin resistance (HOMA-IR), and leptin were measured. Results: This study showed a significant increase in serum triacylglycerol (TG), total cholesterol, glucose levels, and HOMA-IR and a significant decrease in body weight gain, insulin, and leptin levels in the diabetic group compared to the control group. LA treatment induced a significant decrease in glucose, TG, and total cholesterol levels and significantly increased serum insulin and leptin levels in comparison with the diabetic group. Conclusion: Induced diabetes resulted in insulin resistance, hyperlipidemia, and hypoleptinemia, while LA ameliorates these changes and improves insulin sensitivity. (C) 2011 Elsevier Inc. All rights reserved.