Steroidogenic activity of hACTH and related peptides on the human neocortex and fetal adrenal cortex in organ culture.

Explants prepared from the neocortex and the fetal zone of the human fetal adrenal (gestational age 13 to 18weeks) were maintained under conditions of organ culture for 7 to 9 days during which time they were exposed to hACTH and various related peptides. Corticotrophic activity was monitored by the daily release of dehydroepiandrosterone sulfate (3beta-hydroxy-5-androsten-17-one, 3-sulfate; DHA-S) and cortisol as quantified by radioimmunoassay, hACTH (2.2 x 10(-9) - 2.2 x 10(-8)M) was the most active in sustaining steroidogenesis by both neocortical and fetocortical cells. alpha-MSH possessed similar properties but not at concentrations lower than 10(-6)M, whereas CLIP (4.4 x 10(-9) - 1.1 x 10(-7)M), the 18-39 C-terminal moiety of ACTH, was devoid of activity. Corticotrophic activity with respect to fetocortical explants appeared to be that of maintenance of function best illustrated by dehydroepiandrosterone sulfate biosynthesis, while enhancement of steroidogenesis was observed in the neocortex as manifested by cortisol release. Although not eliminating the possible existence of a specific fetal corticotrophin related to ACTH1-39, the data indicate that hACTH is capable of regulating steroidogenesis in the fetal zone which is primarily geared to the formation of dehydroepiandrosterone sulfate.