<i>In Vitro</i>Maturation of Steroidogenic Capacity of Ovine Fetal and Neonatal Adrenal Cells*

Abstract

The in vitro production of total corticosteroids, corticosterone (B), and cortisol (F) by cultured adrenocortical cells from fetuses (115-120 days old) and newborn lambs exposed to ACTH-(1-24) was investigated in relation to the time of culture. Corticosteroids were measured by using an antibody against F, whereas B and F separately were each assayed by specific antibodies after their separation by thin layer chromatography. Basal corticosteroid production by fetal cells increased about 5-fold between days 1 and 6 of culture, whereas the production of B and F increased from 3 +/- (SE) 0.3 to 194 +/- 25 and 3.9 +/- 0.3 to 17.4 +/- 1.9 [ng (8 X 10(5) cells)-1 2 h-1], respectively. ACTH-(1-24) stimulation on day 6 further increased the production of corticosteroids (3.5-fold) and B (2-fold), but had no effect on that of F. When cells were exposed to ACTH-(1-24) from the first day of culture on, there was a dramatic enhancement of F production which became, by day 6, 100 times higher (1746 +/- 149) than in the case of cells maintained in ACTH-free medium. Basal corticosteroid production by nontreated neonatal adrenal cells increased between day 1 and 6, and this was mainly due to B, the production of which increased from 10.1 +/- 0.2 to 447 +/- 35. ACTH-(1-24) stimulation of these cells on day 6 increased 2-fold the secretion of F and 1.5-fold that of B. ACTH-(1-24) treatment (2 h/day for 5 days) of neonatal cells increased 11-fold their production of F as compared with cells cultured in ACTH-free medium, and to a lesser extent that of B. In the second set of experiments, pregnenolone (8 X 10(-5) M) was added to the medium and its conversion to B and F was measured. On day zero the production of B and F by untreated fetal cells was 31 and 16 times higher than that of cells incubated without pregnenolone but stimulated by ACTH-(1-24); however, on day 6 the increase was only 2 and 5 times higher, respectively. On day 6 production of B and F by ACTH-treated cells was modestly increased by the addition of pregnenolone. The capacity of freshly isolated neonatal adrenal cells (day zero) to convert pregnenolone to B and F was 10- and 150-fold higher, respectively, than that of cells from fetuses.(ABSTRACT TRUNCATED AT 400 WORDS)