Inhibition of nitric oxide formation does not protect murine cortical cell cultures from N-methyl-d-aspartate neurotoxicity

We examined the role of nitric oxide in N-methyl-d-aspartate (NMDA) receptor-mediated neurotoxicity in rat and mouse primary cortical cell cultures. In rat and mouse cultures, the NO synthase inhibitor, N^G-Nitro-l-arginine, blocked cGMP formation but not neuronal cell death following a 5–10 min exposure to 300–500 μM NMDA. N^G-Monomethyl-l-arginine was also unable to prevent neuronal death. In contrast, the non-competitive NMDA receptor antagonist, dextrophan, prevented both cGMP formation and cell death. While other data suggest that the synthesis of nitric oxide can mediate NMDA receptor-mediated neurotoxicity, present results suggest that such synthesis is not necessarily required.