Abstract
Corticotrophic activity of opiate-like peptides was assessed by their ability to stimulate the formation of C(21) steroids from [(3)H] progesterone by three-day old cultures of fetal calf adrenal cells. ACTH(1-39), ACTH(α1-24) and a purified preparation of pituitary ovine β-endorphin caused a marked increase in 17α and 21-hydroxylation while a preparation of pure synthetic porcine β-endorphin gave a minimal stimulation. The activity of the purified ovine β-endorphin preparation could not be accounted for by contamination by ACTH or by a synergistic action between the two peptides. The novel pituitary factor described here may be due to a contaminant of the β-endorphin peak which is different from ACTH(1-39).