Nampt/PBEF/visfatin protects PC12 against high glucose-induced neurotoxicity in an in vitro model of diabetic neuropathy via inhibiting oxidative stress, autophagy and apoptosis

Diabetic neuropathy is a well-known complication of diabetes. It has been recently confirmed that hyperglycemia-induced toxicity participates in multiple cellular pathways that are typical for neural deterioration. Nampt/PBEF/visfatin is a novel endogenous ligand, which some studies have shown its neuroprotective effects on neurodegenerative disease. Therefore, we hypothesized that visfatin might prevent high glucose (HG)-induced neurotoxicity via the inhibition of apoptosis, autophagy, and reactive oxygen species (ROS) responses properly. In this study, Pheochromocytoma Cell Line 12 (PC12) cells were exposed to both HG concentrations (50, 75, 100,125, 150 mM) and visfatin (50, 100, 150 ng/ml) in different time-points to determine the optimum time and dose of glucose and visfatin. To investigate the effects of visfatin on HG-induced damage in PC12 diabetic neuropathy model, we examined ROS response, apoptosis, and autophagy by using ROS detection kit, flow cytometry, and Real-time PCR/western blot, respectively. We determined that HG concentration significantly increased ROS level and apoptosis of diabetic PC12 cells. However, visfatin treatment significantly decreased ROS production (P < 0.05) and apoptosis of diabetic PC12 cells (P < 0.0001). Beclin-1 mRNA level (P < 0.05) and Lc3-II protein level (P < 0.05) showed that autophagy pathway is impaired by HG concentrations. We concluded that visfatin could sufficiently decrease neural damage caused by ROS production and apoptosis under HG-induced toxicity.