Dependence of protective effect of α-tocopherol on its concentration and time of action on pc12 cells under conditions of oxidative stress

At the short-term incubation (0.5 and 1.5 h) of cells of the PC12 neuronal line with α-tocopherol, its protective effect against the cytotoxic hydrogen peroxide action was increased with rise of its concentration in samples; the protection was practically absent at action of nanomolar antioxidant concentrations, but was well expressed at its micromolar concentrations. These data agree with the concept that α-tocopherol increases the cell viability by reacting directly with free radicals, which leads to formation of the less reactive compounds deprived of non-paired electron. The evidence is obtained that at the long-term action on PC12 cells, α-tocopherol not only in micro-, but also in nanomolar concentrations increases significantly the cell viability under conditions of oxidative stress. As follows from the obtained data, an important role in realization of the α-tocopherol protective effect at the long-term incubation seems to be played by modulation by this antioxidant of activity of protein kinase activated by extracellular signaling, phosphatidylinosite 3-kinase, and protein kinase C.