A noradrenergic component of quinolinic acid-induced seizures.

Unilateral application of the convulsant brain metabolite, quinolinic acid, to unanesthetized rats resulted in a transient dramatic decrease in norepinephrine levels (nadir -70% after 2 h) in both the injected and the contralateral hippocampus. Dose-response relationships and the temporal sequence of this effect indicated a close functional association between seizure events and the decrease in hippocampal norepinephrine content. Massive release of the inhibitory transmitter, norepinephrine, may thus constitute the brain's defensive response to quinolinic acid-induced seizures.