alpha-Tocopherol protects PC12 cells from hyperoxia-induced apoptosis.

A rat clonal pheochromocytoma cell line (PC12) was cultured under normoxic (21% O2) and hyperoxic (50% O2) conditions. PC12 cells underwent apoptotic cell death when they were cultured in charcoal-stripped medium in a high-oxygen atmosphere. Vitamin E homologs, alpha-tocopherol (alphaT), beta-tocopherol (betaT), gamma-tocopherol (gammaT), and delta-tocopherol (deltaT), were added to the culture medium to study their biological activities. AlphaT was more effective than gammaT and deltaT in preventing hyperoxia-induced cell death. Addition of exogenous alphaT to charcoal-treated medium prevented lactate dehydrogenase (LDH) leakage from PC12 cells and also inhibited the apoptosis, which was accompanied by DNA fragmentation. Additional alphaT was rapidly concentrated in PC12 cells, suggesting that it exerts antioxidant effects. Our data show that PC12 cell death under high-oxygen conditions is due to apoptosis and that, among the vitamin E homologs, alphaT most effectively prevents hyperoxic apoptosis.