HYPOXIC AND EXCITOTOXIC DAMAGE TO CULTURED RAT RETINAL GANGLION-CELLS

The cytotoxic effects of hypoxia and excitatory amino acids on culture d retinal ganglion cells were studied. The influence of coculture with retinal Muller glia and cortical astrocytes on cell survival was eval uated, as were the effects of the N-methyl-DL-aspartate inhibitor, MK- 801. Dissociated retinal neurons from 7-day-old Sprague-Dawley rats we re plated on a laminin substrate, neocortex-derived glial monolayers, or Muller cell monolayers. Ganglion cells were labeled by injection of DiI into the superior colliculus 2 days prior to dissociation. Exposu re of cultured ganglion cells to glutamate and N-methyl-DL-aspartate s howed a time- and concentration-dependent survival rate. Exposure of c ells to hypoxia demonstrated a survival rate that was dependent on tim e and O-2 concentration. Excitotoxic and hypoxic damage was entirely b locked by the specific non-competitive inhibitor of N-methyl-DL-aspart ate, MK-801. Retinal ganglion cells cultured on cortical astrocytes an d retina-derived Muller glia showed significantly better survival rate s (P < 0.001) than cells cultured on laminin-coated dishes under contr ol conditions, in hypoxia (9% to 15% O-2), and after exposure to 200 m u M glutamate. Retinal ganglion cells cultured on Muller glia showed s ignificantly better survival rates (P < 0.01) than those cultured on c ortical astrocytes under conditions of hypoxia (9% to 15% O-2) and exp osure to 200 mu M glutamate. The results demonstrate that excitotoxic and hypoxic damage to cultured retinal ganglion cells is moderated by NMDA receptor blockade and by the presence of glial cells, especially retinal Muller cells. This system may provide a useful model for study ing the pathophysiology of excitotoxicity and hypoxia on cultured reti nal ganglion cells, and may be used to help identify potentially clini cally useful therapeutic agents. (C) 1996 Academic Press Limited