L-nitroarginine, an inhibitor of NO synthase, dramatically worsens limbic epilepsy in rats.

During status epilepticus provoked by an intra-amygdala injection of kainic acid, the severity of seizures and of consequent neuronal damage was considerably increased in rats treated with L-NOARG, at a dose which completely inhibited NO synthesis. We propose that the effects of L-NOARG could be related to the loss of a retrograde inhibition exerted by NO on NMDA receptors. The complete suppression of NO formation in the brain finally facilitated the development and the generalization of seizures and their neurotoxic consequences.