Parallel development of excitotoxic vulnerability to N-methyl-D-aspartate and kainate in dispersed cultures of the rat cerebral cortex

The development of excitotoxic cell death caused by L-glutamate, N-methyl-D-aspartate, quinolinate and kainate was examined in dispersed primary cultures of the rat cerebral cortex. Cell death was evaluated by phase-contrast microscopy and quantified by the measurement of lactic dehydrogenase activity in the culture medium. Cells obtained from embryonic cerebral cortex on days 16-18 of pregnancy, and maintained in a serum-supplemented medium, started to respond to glutamate N-methyl-D-aspartate quinolinate and kainate by cell death on day 7 in vitro. The sensitivity to the neurotoxins increased rapidly, and in a similar fashion, during the second week and remained unchanged up to day 21. Our findings indicate that, unlike the cerebral cortex in situ, the sensitivity of cultured cortical cells to the cytotoxicity mediated by N-methyl-D-aspartate and kainate receptors develops in a nearly parallel fashion.