Leptin attenuates oxidative stress and neuronal apoptosis in hyperglycemic condition

One of the main pathological mechanisms of neurotoxicity in diabetic situation is oxidative stress promoted by hyperglycemia. It has been shown that leptin has neuroprotective effects and may provide neuronal survival signals. This study was designed to reveal the possible neuroprotective effects of leptin in hyperglycemic conditions. Pheochromocytoma (PC12) cell viability was assessed via the MTT test. Cellular reactive oxygen species (ROS) generation was determined by DCFH-DA analysis. The malondialdehyde (MDA) and glutathione (GSH) levels were measured in high-glucose-treated PC12 cells with and without leptin cotreatment. Western blotting was performed to measure apoptosis markers (Cleaved caspase-3 and Bax/Bcl2 ratio). Elevation of glucose levels (100 mmol/L) consecutively increased intracellular ROS and MDA level, and apoptosis in PC12 cells after 24 h leptin administration (12 and 24 nmol/L) decreased the high-glucose-induced cell toxicity, caspase-3 activation, and Bax/Bcl-2 ratio. Also, cotreatment with leptin (12 and 24 nmol/L) significantly reduced oxidative damage to PC12 cells in high-glucose condition, as reflected by the diminution in MDA and ROS levels and the increase in GSH content. Our finding demonstrates that leptin has protective effects against hyperglycemia-induced neural damage. This could be related to the attenuation of oxidative stress and neural apoptosis.