Prenatal and postnatal ovine adrenal cell responses to prostaglandin E-2

OBJECTIVE: To examine the secretory effect of prostaglandin E-2 (PGE(2)) an d ACTH on the adrenal glands of prenatal and postnatal sheep. METHODS: Immunocytochemistry was used to examine the adrenal cortex and med ulla for 17 alpha -hydroxylase and tyrosine hydroxylase immunoreactivity. M icrophysiometric technique was used to measure [H+] after exposure of whole dispersed prenatal and postnatal adrenal glands to PGE(2), ACTH, or both. RESULTS: Immunocytochemistry showed many cortical-type cells in all adrenal medullae and many medullary-type cells in fetal adrenal cortices. Maximum H+ responsiveness to PGE(2) decreased with increasing age. The developmenta l age-related pattern of maximum percentage change in [H+] during ACTH expo sure was similar to previous findings with cortisol production as the endpo int. ACTH stimulated H+ production at 80 days' gestation and at all ages gr eater than 125 days' gestation (P < .05). The molar concentration of ligand required to elicit a response that tvas 50% of maximum response (EC50) for the ACTH response was lower in fetuses than in newborn lambs (<1 day and 3 days old), bmt there was no change in EC50 for PGE(2) across the ages stud ied. Adrenal cell response to ACTH after prior ACTH and PGE(2) exposure was higher (P < .05) compared with ACTH after ACTH or ACTH alone at 110 days' gestation only and was lower in S-day-om lambs. CONCLUSIONS: Bared an the ACTH results, microphysiometry was a valid method for investigating dispersed adrenal cell physiology. Prostaglandin E-2 sti mulated dispersed adrenal cells during the mid-gestation ACTH refractory pe riod, but this effect decreased with increasing age. Prostaglandin E-2 sens itized adrenal cells to ACTH at 110 days' gestation but inhibited ACTH effe cts at postnatal day 3. Copyright (C) 2001 by the Society for Gynecologic I nvestigation.