Excitatory amino acid-induced cytotoxicity in primary cultures of mouse cerebellar granule cells correlates with elevated, sustained c-fos proto-oncogene expression.

An elevated, sustained expression of c-fos mRNA was found in primary cultures of mouse cerebellar granule cells following exposure to toxic concentrations of the excitatory amino acids, L-glutamate, L-homocysteate, S-sulpho-L-cysteine and N-methyl-D-aspartate (NMDA), using leakage of lactate dehydrogenase (LDH) as an indicator of cytotoxicity. In contrast, when used at non-toxic concentrations these compounds induced a rapid and transient increase in c-fos mRNA levels. Both LDH release and elevated, sustained c-fos mRNA induction were blocked (in the case of L-homocysteate) or reduced (in the case of L-glutamate and S-sulpho-L-cysteine) by the selective NMDA receptor antagonist (DL(+/-)-2-amino- 5-phosphonopentanoic acid) whereas 6-cyano-7-nitroquinoxaline-2,3-dione (a selective antagonist at non-NMDA ionotropic receptors) had no effect. These data suggest a role for altered c-fos mRNA expression in excitotoxic mechanisms.