Different roles for the pituitary and adrenal cortex in the control of enkephalin peptide localization and cortico-medullary interaction in the sheep adrenal during development.

We have investigated the effect of adrenocorticotrophic hormone (ACTH) replacement after fetal hypophysectomy on the pattern of localization of enkephalin-containing peptides (enkephalins) and phenylethanolamine N-methyltransferase (PNMT) in the fetal sheep adrenal. We have also investigated the relative roles of the fetal pituitary and adrenal cortex in determining the extent of the interdigitation of the peripheral adrenaline (AD)-containing cells of the adrenal medulla with the inner zones of the adrenal cortex in the late gestation fetus. Fetal hypophysectomy (Hx; n = 12) or sham operations (n = 8) were performed at 109-118d. At 138 or 139d, ACTH (1-24) (10.5 micrograms/h) was infused intravenously for 72 h into 4 Hx fetuses (Hx + ACTH group). Saline was infused for 72 h into 4 Hx fetuses (Hx + Sal) and into 4 sham-operated fetal sheep (Intact + Sal). Fetal adrenal glands were collected at autopsy from 141/2d Intact + Sal, Hx + Sal and Hx + ACTH groups, from 4 intact fetal sheep at 145-147d gestation (145/7d Intact group) and 4 Hx fetal sheep at 147-164d gestation (147/64d Hx group). Adrenals were also collected from 4 newborn lambs at 10-12d after birth (10/12d Newborn group). Using the peroxidase-antiperoxidase immunocytochemical staining method, sections of adrenal glands (10-12 microns) from all groups were stained anti-PNMT. Sections of adrenal glands from the 141/2d groups were also stained separately with anti-dopamine-beta-hydroxylase (anti-D beta H) and anti-enkephalin (anti-ENK).(ABSTRACT TRUNCATED AT 250 WORDS)