Functional maturation of the primate fetal adrenal in vivo. II. Ontogeny of corticosteroid synthesis is dependent upon specific zonal expression of 3 beta-hydroxysteroid dehydrogenase/isomerase.

Abstract

Cortisol, produced by the primate fetal adrenal, regulates the maturation of organ systems necessary for extrauterine life. During most of primate pregnancy, however, the fetal adrenal lacks the enzyme 3 beta-hydroxysteroid dehydrogenase/isomerase (3 beta HSD), which is essential for cortisol synthesis. Therefore, we used immunohistochemistry and in situ hybridization techniques to investigate the developmental expression of 3 beta HSD in the fetal rhesus monkey adrenal from 109 days' gestation until term (165 +/- 5 days) and assessed the role of ACTH in the induction of its expression and localization. We also examined whether ACTH regulates the expression of two other steroidogenic enzymes, cytochrome P450 cholesterol side-chain cleavage (P450scc) and P450 17 alpha-hydroxylase, 17/20-lyase (P450c17), in the fetal rhesus monkey adrenal. To stimulate ACTH secretion from the fetal pituitary in vivo, we administered metyrapone to late gestation fetal rhesus monkeys for 3-7 days. Adrenals were collected from untreated fetuses at 109-125 days (n = 5), 130-148 days (n = 7), 155-172 days (n = 4), and after metyrapone treatment at 135-137 days (n = 4). The cortical width and total amount of 3 beta HSD staining were measured using an image analysis system. 3 beta HSD was localized primarily in the definitive zone cells of the adrenal from fetuses between 109-148 days, whereas at term (155-172 days), 3 beta HSD was localized in both definitive and transitional zone cells. The cortical width and total amount of 3 beta HSD staining in the adrenal increased significantly (P < 0.05) between 148 days (137 +/- 14 microns and 3,689 +/- 522 grains) and 155 days (315 +/- 61 microns and 7,321 +/- 2,008 grains). Interestingly, in metyrapone-treated fetuses at 135-137 days, 3 beta HSD messenger RNA (mRNA) and protein were localized extensively in both the definitive and transitional zones, a pattern seen only in term fetal adrenals in untreated animals. In addition, metyrapone treatment significantly (P < 0.05) increased cortical width (386 +/- 95 microns) and total 3 beta HSD immunostaining (29,063 +/- 13,692 grains) compared with age-matched controls. In contrast to 3 beta HSD, P450scc mRNA was detected in the definitive, transitional, and fetal zones, and its expression was not altered after metyrapone treatment. P450c17 mRNA was detected in the transitional and fetal zones, and the relative abundance was greater in the transitional zone. The relative abundance of P450c17 mRNA was increased in the fetal zone after metyrapone treatment. In summary, at term or after metyrapone treatment, expression of 3 beta HSD is induced in the transitional zone of the fetal rhesus monkey adrenal gland, an indication of functional maturation of the primate adrenal cortex. These data suggest that the ontogenetic increase in fetal pituitary ACTH secretion plays an important role in the induction of 3 beta HSD expression in the transitional zone.

Differential Actions of Metyrapone on the Fetal Pituitary-Adrenal Axis in the Sheep Fetus in Late Gestation1

“…Metyrapone treatment for 3-7 days similarly resulted in an increase in both adrenal growth and adrenocortical cell size in the primate fetus [39]. The most likely factor responsible for the increased adrencortical growth in the metyrapone-infused fetuses is either ACTH or another trophic peptide derived from POMC.…”

Functional Biology of the Primate Fetal Adrenal Gland: Advances in Technology Provide New Insight

“…[14][15][16][34][35][36] In our initial studies, we chose to investigate the expression of three enzymes, namely cytochrome P450 cholesterol side-chain cleavage (CYP11A1), cytochrome P450 17 ␣ hydroxylase (CYP17) and 3 ␤ hydroxysteroid dehydrogenase (3 ␤ HSD), which play a pivotal role in sthe teroidogenesis pathway and define the steroidogenic potential of the different zones in the adrenal cortex. 35,36 As further factors have been identified as being necessary for complete adrenal steroidogenic function, such as steroidogenic factor-1(SF-1), steroidogenic acute regulatory protein (StAR), adrenocortical cytochrome b5 and DHEAsulphotransferase, additional studies have been undertaken to examine their spatial and temporal localization. The findings from these studies have provided further evidence to support our original conclusions and have added to our current understanding of the functional capabilities of the developing primate adrenal cortex [37][38][39] (see Fig.…”

“…[34][35][36][37][38]41 morphological appearance, which appears to function as a reservoir of precursor stem cells and does not acquire a steroidogenic phenotype enabling it to secrete aldosterone until close to term; (ii) the transitional zone, located at the interface between the inner fetal zone and the definitive zone, which begins functioning by approximately 24-28 weeks of human pregnancy and possesses enzymes necessary to produce cortisol (CYP11A1, CYP17) and 3 ␤ HSD; and (iii) the large inner fetal zone, which begins functioning early in pregnancy and possesses the enzymes necessary for the synthesis of the androgen DHEA and DHEA-S (CYP11A1, CYP17 and sulphokinase). 35,36 Based on the functional capacities of the definitive zone, transitional zone and fetal zone, we proposed that these three zones are analogous to the zona glomerulosa, zona fasciculata and zona reticularis, respectively, of the mature adrenal cortex. 2,[14][15][16][34][35][36] Given the small size of the fetal rhesus monkey and the hyperreactivity of the primate uterus to intervention, few studies have investigated the in vivo responsiveness of the fetal pituitary-adrenal axis.…”

Developmental changes in steroidogenic enzymes in human postnatal adrenal cortex: immunohistochemical studies

“…A portion of DHEA is subsequently sulphated to DHEAS by dehydroepiandrosterone sulfotransferase (DHEA-ST). Intra-adrenal localization of these steroidogenic enzymes has been documented in human and primate adrenal gland (Mesiano et al, 1993;Sasano, 1994;Coulter et al, 1996;Mesiano & Jaffe, 1997;Coulter & Jaffe, 1998). However, the alterations of intra-adrenal steroidogenic enzymes during human postnatal development have not been examined in detail, and alterations of steroidogenesis of C 19 steroids in the adrenal during adrenarche remain unknown.…”