Serum levels of insulin and leptin in lipoic acid- treated and nontreated experimentally diabetic rats

Diabetes is characterized by hyperphagia, and polydypsia. However, the mechanisms by which diabetes produces these effects are not clear. This study was conducted to examine changes in serum insulin and leptin levels in induced-type 1 diabetes mellitus in relation to concomitant changes in body weight, glycemic state and lipid profiles in rats. Moreover, we aimed to clarify that the treatment with lipoic acid (LA) is capable of reversing these effects or not. Ninety-six male rats were divided into 3 groups, control group (32 rats) was considered as normal non-diabetic, 64 rats were subcutaneously injected with alloxan (120 mg/kg.b.wt) for induction of diabetes. Then the diabetic rats were divided into two equal subgroups, the first is diabetic group that was not treated with LA, and the other is LA-treated diabetic group that was treated with LA at a dose 100 mg/kg b.wt / day for four weeks. Body weight, serum lipid profile, glucose, insulin, homeostasis model assessment– insulin resistance (HOMA-IR) and leptin were measured. The data showed significant increase in serum triacylglycerol, total cholesterol and glucose levels as well as HOMA-IR while significant decrease in the mean body weight gain, serum insulin and leptin levels in diabetic group in comparison with control group. The treatment with lipoic acid led to significant decrease in serum fasting and postprandial glucose, triacylglycerol and total cholesterol levels as well as slight decreased HOMA-IR with significant increased levels of serum insulin and leptin in comparison with diabetic group. It could be concluded that alloxan-induced diabetes led to hyperglycaemia, insulin resistance, hyperlipideamia and hypoleptinamia. Moreover, treatment with lipoic acid ameliorates these changes and improves insulin sensitivity.