Loss of sensitivity to ACTH of adrenocortical cells isolated from maturing domestic fowl

Maturation of domestic fowl corticosteroidogenesis was evaluated using purified adrenocortical cells. Basal corticosterone production decreased steadily from 2 days to 26 weeks after hatching. However, maximally stimulated corticosterone production was not changed. In contrast, the half-maximal steroidogenic concentrations (ED50 values or effective doses for 50% maximal effect) of ACTH analogs increased approximately 40 times by 26 weeks, but the ED50 values of 8-bromo-cyclic AMP and pregnenolone were not changed. This suggests that adrenocortical cell sensitivity to ACTH decreases with maturation of the domestic fowl.