Protective action of zinc against glutamate neurotoxicity in cultured retinal neurons.

PURPOSE To examine the effects of Zn2+ on glutamate-induced neurotoxicity in cultured retinal neurons. METHODS Primary cultures obtained from fetal rat retinas (16 to 19 days gestation) were used. The neurotoxic effects of excitatory amino acids were quantitatively assessed using the trypan blue exclusion method. RESULTS A brief exposure of retinal cultures to glutamate or N-methyl-D-aspartate (NMDA) induced delayed cell death. Zn2+ at concentrations of 3 to 30 microM ameliorated glutamate- and NMDA-induced neurotoxicity in a dose-dependent manner. By contrast, neurotoxicity induced by a 1-hour exposure to kainate was not affected by Zn2+. CONCLUSIONS These findings demonstrate that Zn2+ protects retinal neurons from NMDA receptor-mediated glutamate neurotoxicity.