Ginkgolide B attenuates ethanol-induced neurotoxicity through regulating NADPH oxidases

Ethanol has long been demonstrated to trigger cell apoptosis in the central nervous system. The over-production of reactive oxygen species (ROS) is considered as one of the most important mechanisms involving in the apoptosis caused by ethanol. Ginkgolide B (GB), which was widely used as a monomer of traditional Chinese medicine, was reported to scavenge free radicals in endothelial cells and smooth muscle cells. But whether GB can prevent ethanol-induced neurotoxicity is still unknown. The aim of this study was to investigate effects of GB on ethanol-induced cytotoxicity, oxidative stress and apoptosis and explore potential protective molecular mechanism of GB. It was found that GB inhibited cell injury and apoptosis in a dose-dependent manner in ethanol-treated PC12 cells by MTT and LDH assays. It was also found that activities of caspase-3 increased by ethanol were mostly abrogated by GB. Further, GB decreased the production of ROS and subsequent over-production of lipid peroxides. A significant increase of alcohol dehydrogenase (ADH) and CYP2E1 enzyme activity was found in the ethanol-exposed PC12 cells as compared to controls. However, GB pretreatment did not significantly affect ethanol-induced ADH and CYP2E1 activities. Quantitative real-time PCR and Western blot analysis demonstrated that ethanol treatment resulted in a significant increase in mRNA and protein expression of NADPH oxidases, which are main oxidases producing ROS in neurons. Moreover, expression and activities of NADPH oxidases were down-regulated by GB. These results indicate that ethanol-induced neurotoxicity is ameliorated by GB mainly through regulating expression and activity of NADPH oxidases.