Protective effects of alpha lipoic acid on high glucose-induced neurotoxicity in PC12 cells

Hyperglycemia plays an important role in the development of diabetic neuropathy. In this study, we investigated the protective effects of alpha lipoic acid (ALA) against high glucose-induced neurotoxicity in PC12 cells as a suitable in vitro model for studying neuronal functions. PC12 cells were treated with high glucose (25 mg/ml for 24 h) in the absence and presence of ALA (100 μM for 24 h). The viability of PC12 cells was estimated by using MTT assay. The expression of pro- apoptotic Bax, anti- apoptotic Bcl-2 and caspase 3 protein were evaluated by western blotting. The reactive oxygen species (ROS) levels were determined with 2,7-dichlorodihydro- fluorescein diacetate (H₂DCFDA). Biochemical markers of oxidative stress were assessed by using the total antioxidant power (TAP), lipid peroxidation (LPO), ADP/ATP ratio, activity of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). Pretreatment of PC12 cells with ALA, significantly improved high glucose-induced toxicity by increasing activity of antioxidant enzymes CAT and SOD in the PC12 cell. It also increased the concentrations of TAP. An elevated level of cell death and ROS in high glucose conditions, diminished with ALA treatment. Over expression of Bax and caspase 3 protein, elevation of ADP/ATP ratio and LPO level in high glucose- treated PC12 cells, were significantly reduced by ALA. It was concluded that ALA attenuates neurotoxicity induced by high glucose in PC12 cells.