RELATIONSHIP BETWEEN ACTH-SECRETION AND CORTICOID BINDING TO SPECIFIC RECEPTORS IN PERIFUSED ADENOHYPOPHYSES

This study reports on the kinetics of glucocorticoid-induced inhibition of ACTH release, together with steroid binding to specific pituitary receptors. It was shown that corti-costerone (CORT) inhibited ACTH output provoked by either corticotropin-releasing factor (CRF) extracts or dbcAMP, in a manner which was both dose-and time-dependent. A close correlation appeared to exist between the degree of ACTH blockade and the percentage of filled steroid-binding sites. However, exposure of hypophyses to CORT for a critical period of time was a prerequisite for such a relationship to develop. Furthermore, it was found that dexamethasone (DEX) was more potent than CORT in inhibiting ACTH secretion and, in addition, bound to a greater extent to nuclei of pituitary cells. These data suggest the existence of a close correlation between occupancy of pituitary glucocorticoid receptors and modulation of ACTH secretion. © 1979 S. Karger AG, Basel.