NITRIC-OXIDE PROMOTES SEIZURE ACTIVITY IN KAINATE-TREATED RATS

L-Arginine-derived nitrogen monoxide (NO) formation was determined in different regions of the rat brain during kainate-induced seizures. NO was trapped in vivo as a paramagnetic mononitrosyl-iron diethyldithio carbamate complex, the concentration of which was determined ex vivo b y cryogenic electron spin resonance spectroscopy. Basal NO formation ( 0.3-0.8 nmol g(-1) tissue 30 min(-1)) was detected in the brain of con trol rats. In kainate-injected rats NO formation was increased six-fol d within 30-60 min in the amygdala/temporal cortex region, and up to 1 2-fold, though more slowly, in the remaining cortex. The kainate-elici ted convulsions and NO formation were attenuated in animals pretreated with either 7-nitroindatele, a specific inhibitor of neuronal NO synt hase, or diazepam. These findings identify NO as a proconvulsant media tor in kainate-evoked seizures.