EVIDENCE FOR DUAL CORTICOSTEROID-RECEPTOR MECHANISMS IN THE FEEDBACK CONTROL OF ADRENOCORTICOTROPHIN SECRETION

Abstract

SUMMARY The influence of several corticosteroids on stress-induced secretion of adrenocorticotrophin was studied. Two periods of inhibition were demonstrated. Fast feedback occurred within minutes with small doses of corticosterone, and was of short duration which was further curtailed as the dose of corticosterone was raised. Delayed feedback occurred after 1 h or later, required larger doses and the duration of inhibition was increased with increased dosage. Corticosterone and cortisol were agonists on both fast and delayed feedback. However, 11-deoxycorticosterone and 11-deoxycortisol were antagonists on fast feedback but agonists on delayed feedback. It is concluded that the two feedback mechanisms have different dynamics and separate receptors.