Cytoprotective Effect of α-Lipoic Acid on RIN-m5F Cultured with High Glucose

Abstract:

The aim of this study is to investigate whether α-lipoic acid(α- LA) prevents high glucose-induced oxidative damage and apoptosis of pancreatic islet beta cells. In the present sudy，RIN-m5F cells were incubated with different concentration of glucose(11 mmol/L，22 mmol/L and 44 mmol/L) in the presence or absence of 200 mol/L α-LA for 72 h. Then，cellular reactive oxygen species(ROS) levels，malandialdehyde(MDA) levels，total antioxidant capacity(T-AOC) and superoxide dismutase(SOD) activity were assayed with the appropriate test kits；mitochondrial membrane potential was detected by flow cytometry；relative genes levels were analyzed by reverse transcriptase polymerase chain reaction；western blotting was used to determine protein expression of GSK-3β and p-GSK-3β(Ser9). The results show that α-LA significantly reduced the MDA formation and inhibited the ROS production induced by high glucose，whereas increased T-AOC and SOD activity. Additionally，α- LA induced membrane depolarization and increased mitochondrial membrane potential. These effects were mediated by Bcl-2 associated X protein(BAX) and B-cell lymphoma-2(BCL-2) expression. Western blotting indicated that α-LA inhibited GSK-3β by increasing p-GSK-3β(Ser9) level. Therefore，our data suggest that α-LA can effectively attenuate high glucose-induced RIN-m5F cell oxidative damage and apoptosis，by mechanisms which probably involves the inactivation of GSK-3β by phosphorylation. These findings provide a new interpretation on the role of α-LA in the treatment of diabetes.