DIRECT EVIDENCE FOR THE ROLE OF NITRIC-OXIDE ON THE GLUTAMATE-INDUCEDNEURONAL DEATH IN CULTURED CORTICAL-NEURONS

It has been reported that glutamate-induced neurotoxicity is related t o an increase in nitric oxide (NO) concentration. An NO-sensitive elec trode has been developed to measure NO concentration directly. Using t his electrode, we examined NO concentration and neuronal survival afte r glutamate application in rat cultured cortical neurons. We also exam ined the effects of NMDA receptor antagonists, MK-801 and ketamine, an d the NO synthetase inhibitor, L-NMMA on NO production and neuronal de ath. After 7 days in culture, application of glutamate (1 mM) or L-arg inine (0.3 mM) to the cultured medium increased NO concentration, and decreased the number of anti-microtubule-associated protein 2 positive neurons. Both pretreatment with MK-801 (300 mu m) and ketamine (300 m u m) prevented glutamate-, but not L-arginine-induced increase in NO c oncentration and neuronal death. L-NMMA prevented both glutamate- and L-arginine-induced NO production and neuronal death. The nitric oxide donor, S-nitroso-N-acetyl-D,L-penicillamine (SNAP) also caused neurona l death, and MK-801, ketamine and L-NMMA did not prevent SNAP-induced toxicity. We have demonstrated excitatory amino acid-induced changes o f NO concentration and the parallel relationship between changes of NO concentration and neuronal death. In conclusion, an increase in NO co ncentration does induce neuronal death, and the inhibition of the prod uction of NO prevents glutamate-induced neuronal death. (C) 1998 Elsev ier Science B.V.