Abstract
INTRACRANIAL administration of metyrapone, a blocker of the enzyme 11 -β-hydroxylase, which is essential for the biosynthesis of corticosteroids, resulted in profound stimulation of the nucleus preopticus and the CRF- ACTH axis in the teleost, Clarias batrachus. It is suggested that the putative blockade of the neurosteroid biosynthesis following metyrapone might be responsible for this action. The present study for the first time uncovers the possibility of inhibitory regulation of the CRF-ACTH axis by metyrapone sensitive neurosteroids.