AJP - Regulatory, Integrative and Comparative Physiology, Vol 252, Issue 4 743-R748, Copyright © 1987 by American Physiological Society
Negative-feedback inhibition of fetal ACTH secretion by maternal cortisol
C. E. Wood
Previous studies in this laboratory have shown that small increases in
fetal cortisol (F) decreased basal fetal plasma renin activity (PRA) and
completely inhibited the fetal adrenocorticotropin hormone (ACTH) response
to hypotension. The present study was designed to quantitate suppression of
fetal ACTH and renin secretion by maternal F. Fetal and maternal femoral
arteries and veins were chronically catheterized (11 fetuses, 118-129 days
gestation). Maternal intravenous infusion of 0, 0.5, 1.0, and 2.0
micrograms F X kg-1 X min-1 (n = 5-6) increased mean maternal and fetal
cortisol and suppressed fetal ACTH responses to a subsequent period of
hypotension in a dose-related manner. Increases in fetal plasma cortisol to
8.3 ng/ml completely suppressed the fetal ACTH response to hypotension. The
results indicate that increases in maternal plasma cortisol concentration
sufficient to produce modest increases in fetal plasma cortisol inhibit
fetal ACTH secretion.
