CORTICOTROPIN-RELEASING HORMONE IS A RAPID AND POTENT CONVULSANT IN THE INFANT RAT

Corticotropin-releasing hormone (CRH) administered into the cerebral ventricles of rats during the first postnatal week caused a specific and stereotyped behavior sequence: rhythmic chewing and licking (jaw myoclonus) were followed by 'limbic'-type seizures. The onset of the seizures was much more rapid (2-45 min vs 3-7 h) than in adult rats, and the convulsant doses were much lower (50 x 10(-12) mol per gram brain weight vs 750 x 10(-12) mol per gram brain weight in adults). CRH potency in inducing seizures varied inversely with age. CRH-induced seizures occurred prior to any changes in serum corticosterone, and were eliminated by the administration of a CRH antagonist, as well as of phenytoin. Electrocorticographic correlates of CRH-induced behaviors in the infant rat were inconsistent, suggesting a subcortical origin of CRH-induced paroxysmal events in the immature brain.