Leptin and Insulin Interaction Modulates Pancreatic Nitric Oxide Levels in Diabetic Rats

Background and Objective: Diabetes mellitus, characterized by hyperglycemia due to insulin secretion deficits, involves the crucial influence of leptin on pancreatic hormones. Nitric oxide (NO), a key signal molecule, is vital for leptin’s action in various cell types, including pancreatic β-cells. This study investigates the interplay of leptin and insulin with NO in streptozotocin-induced diabetic rats. Materials and Methods: Rats were categorized into seven groups: Control, Streptozotocin (Diabetes), Leptin, Insulin, Streptozotocin+Leptin, Streptozotocin+Insulin and Streptozotocin+Leptin+Insulin. Regular blood glucose measurements, serum leptin and insulin level determinations, immunohistochemical detection of nitric oxide synthases and leptin expressions and histopathological examinations were conducted. Results: Blood glucose levels in Streptozotocin+Insulin and Streptozotocin+Leptin+Insulin groups closely resembled those in the control group. Weaker inducible nitric oxide synthase immunoreactivity was observed in the Streptozotocin+Leptin, Streptozotocin+Insulin and Streptozotocin+Leptin+Insulin groups compared to the Streptozotocin group. Positive leptin immunoreactivity was intense in the islets of the Streptozotocin+Leptin+Insulin group. Conclusion: Combined leptin and insulin treatment normalized hyperglycemia in diabetic rats by suppressing inducible nitric oxide synthase availability and enhancing insulin sensitivity in the pancreas.