Excitotoxicity of glutamate and four analogs in primary spinal cord cell cultures

Continuous glutamate exposure produced widespread neuronal damage in mixed whole dissociated murine spinal cord cell cultures. Ethidium bromide and acridine orange staining revealed that a 24 h glutamate exposure produced nearly 98% neuronal cell death but the underlying glia were spared. Continuous exposure to glutamate, N-methyl-D-aspartate (NMDA), kainate and quisqualate produced time-dependent and dose-dependent cell death as measured by the assay of lactate dehydrogenase activity in the cell culture media. Glutamate (500 microM), NMDA (100 microM) and kainate (500 microM) were equally neurotoxic. In contrast, quisqualate (100 microM) was only partially neurotoxic compared to the other glutamate analogs. The neurotoxicity of glutamate was blocked by the NMDA antagonist, MK-801. The neurotoxicity of kainate and quisqualate was blocked with the non-NMDA antagonist CNQX. Continuous exposure to (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) was not neurotoxic, even at concentrations up to 1 mM.