Increasing Fetal Adrenal Formation of Cortisol from Pregnenolone During Baboon (Papio papio) Gestation

Abstract

To determine the maturational changes leading to adrenocortical self-sufficiency in baboon neonates, fetal adrenal growth and cortisol (F) production, in vitro, from pregnenolone (P₅), progesterone (P₄) and 11-deoxycortisol (S) were examined at various times during gestation. Adrenal weight of animals delivered prematurely (100-179 days gestation, term = 184) by cesarean section (N = 17) or spontaneously (N = 13) at term (181 ± 4 days, X ± SE), tripled during the second half of gestation (r = 0.82; P0.017X) and resulted primarily from growth of cortical fetal zone tissue. F production from [³H]P₅, [³H]P₄ or [³H]S (15 µCi, 1Oµg) by 50 mg homogenized tissue from selected glands incubated with NADPH was determined following extraction, and purification of [³H]F. Results were combined from animals delivered by cesarean section 84 to 54 days (N = 4), or 24 to 17 days prior to term (N = 3) and from neonates 1 day old (N = 3) or 5 and 12 days old (N = 2). F production from S (68.2 percent ± 13.1 percent, X ± SE) and P₄ (42.4 percent ± 2.9 percent) either remained constant or decreased during the study period, while that from P₅ (6.9 percent ± 1.9 percent) increased (P4 (46-77 nmole/2 adrenals) remained constant whereas that from P₅ increased (P5 for F synthesis towards term. These changes may be important in ensuring adrenocortical self-sufficiency when, after delivery, placental P₄ is no longer available for F production.