Whether peptide hormones other than ACTH may be responsible for the difference in size or rate and pattern of steroidogenesis of the fetal zone (FZ) compared to those of the neocortex (NC) of the human fetal adrenal gland is controversial. In the present investigation, the activity of adenylate cyclase in membrane fractions of separated zones of the human fetal adrenal gland was determined. Basal adenylate cyclase activity was 2- to 3-fold greater in NC than in FZ membrane fractions. The addition of ACTH-(1-24) stimulated adenylate cyclase activity in both zones, but the activity was more sensitive o t ACTH (10-10 M) in NC fractions than in FZ fractions (10-7 M). In addition to ACTH-(1-24), the effect of other ACTH-related peptides on the activity of adenylate cyclase in the separated zones of the adrenal gland was investigated. 16K fragments 2-36, γ3MSH, αMSH, β-endorphin, leu-enkephalin, and met-enkephalin, as well as hCG, FSH, prostaglandin (E2 prostaglandin (F2α epinephrine, and norepinephrine did not stimulate adenylate cyclase activity in either zone. It is concluded that basal and ACTH-(1-24)-stimulated adenylate cyclase activities are greater in NC than in FZ membrane fractions. In addition, the results of the present investigation do not support the concept that other ACTH-related peptides or peptide or protein hormones increase steroidogenesis by stimulating ade-nylate cyclase activity in the human fetal adrenal gland.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Clinical Biochemistry
- Biochemistry, medical