Lipid Peroxidation, Antioxidative Enzyme Activities, and Cytosolic Free Calcium Levels in Rat Hippocampus-Derived Cells Exposed to Free Radicals

Abstract

To elucidate mechanisms of free radical-induced neuronal cell death, lipid peroxidation measured as thiobarbituric acid-reactive substances (TBARS), three antioxidative enzyme activities (superoxide dismutase, glutathione peroxidase, and catalse), and cytosolic free Ca2+ (Ca2+i) were examined in rat hippocampus-derived cells (HV 16-4) exposed to free radicals generated by a hypoxanthine-xanthine oxidase system. The viability of cells decreased with an increase in numbers of free radical positive cells in a dose-dependent manner of xanthine oxidase. The protein-bound TBARS did not change, whereas free TBARS increased at 135% of initial value. No remarkable change was observed in three antioxidative enzyme activities. On the other hand, Ca2+i increased after exposure followed by cell death. Furthermore, the addition of Co2+, a nonspecific Ca2+ channel blocker, delayed the increase of Ca2+i and subsequent cell death. These findings suggested that the influx of Ca2+ played a crucial role for HV16-4 cell death induced by free radicals.