Endocrinology, Vol 105, 613-617, Copyright © 1979 by Endocrine Society
alpha-Melanocyte-stimulating hormone and adrenocorticotropin in the regulation of glucocorticoid secretion during the perinatal period in sheep
AJ Llanos, J Ramachandran, RK Creasy, AM Rudolph and M Seron-Ferre
To determine the role of other ACTH-like peptides in the regulation of
glucocorticoid secretion in fetal sheep, we examined the responses of the
adrenal gland of fetal and newborn sheep to comparable single doses of
alpha MSH (75 micrograms) or ACTH (50 micrograms) during the last third of
gestation and the first month of postnatal life. alpha MSH first increased
the plasma glucocorticoid concentration at 121--130 days of gestation [from
16 +/- 1.5 to 36.9 +/- 9 (SE) ng/ml]; the response to alpha MSH persisted
on days 131--140 of gestation and during the first month after birth. ACTH
first increased the plasma glucocorticoid concentration at 131--140 days of
gestation and increased it further in the first month after birth (from
18.9 +/- 3.6 to 97.0 +/- 10 ng/ml). The observations that the adrenal
glands of fetuses and newborn lambs responded to alpha MSH at a dose
comparable to that of ACTH and that the response to alpha MSH in the fetus
preceded the response to ACTH may indicate that adrenal receptors mature
during fetal development. These data also suggest that the regulation of
the adrenal during fetal life may involve more than one tropic hormone.
