OXYGEN RADICAL-INDUCED NEUROTOXICITY IN SPINAL-CORD NEURON CULTURES

The neurotoxic effects of oxygen radicals on spinal cord neuron cultur es derived from fetal mouse have been studied. Oxygen radicals, supero xide radical and hydrogen peroxide, were generated by adding xanthine oxidase and hypoxanthine in the culture medium. Exposure of neurons to this oxygen radical-generating system resulted in a significant cell death and decrease of choline acetyltransferase (ChAT) activity in a t ime-dependent manner in spinal cord neuron cultures. The decrease in c ell viability and ChAT enzyme activity induced by the oxygen radicals was blocked by scavengers such as superoxide dismutase (SOD), catalase , and tetrakis (2-pyridylmethyl) ethylenediamine (TPEN), a metal chela tor. Antagonists of the N-methyl-D-aspartate (NMDA) receptor, includin g MK801 (a noncompetitive NMDA antagonist), D-2-amino-5-phosphonovaler ic acid (APV) (a competitive NMDA antagonist), and 7-chloroky-nurenic acid (an antagonist at the glycine site associated with the NMDA recep tor), similarly blocked oxygen radical-induced decrease in cell viabil ity and ChAT activity in spinal cord neuron cultures. These results in dicate that both oxygen radicals and excitotoxic amino acids were invo lved in the oxidant-initiated neurotoxicity of spinal cord neurons. (C ) 1994 Wiley-Liss, Inc.