Ontogenesis of Circadian Pituitary-Adrenal Periodicity in Rats Affected by Neonatal Treatment wth ACTH 1

Summary

Neonatal treatment with ACTH on days 7-9 and 17-19 suppressed the circadian corticosteroid rhythm in adult rats. Treatment with gel vehicle at these ages, except in females on days 17-19, or with ACTH or gel vehicle at other times neonatally did not produce similar effects. Thus, brief exposure to high circulating levels of ACTH and/or corticosteroids during two critical neonatal periods affects the normal development of mechanisms underlying cyclic pituitary-adrenal function in the rat.