I. Physiological Significance of the Fetal Adrenal IN MOST mammalian species, products of the fetal adrenal gland appear to play an important role in regulating maturation of various organ systems in the fetus (1–5), providing the fetus homeostatic mechanisms to respond to stress (6), and initiating and/or participating in the cascade of events culminating in the birth of a newborn (7–9). Thus, cortisol, presumably of fetal adrenal origin, is one of the chemical messengers involved in the stimuli to lung maturation (3,4), deposition of glycogen in the liver (10, 11), and induction of several enzymes in the fetal brain, retina, pancreas, and gastrointestinal tract (12–17) that normally are associated with late intrauterine life. It is well known, from the elegant work of Liggins and colleagues (7), that ablation of the fetal adrenal in sheep prevents parturition, whereas infusion of cortisol or ACTH1 to the fetus induces premature delivery. Although evidence that the fetal adrenal of the human or nonhuman ...

Regulation of the primate fetal adrenal cortex.

Publisher Summary Fetal adrenal has the same intrinsic properties and responds to the same pituitary regulatory mechanisms as in postnatal life. The transformation of fetal zone cells occurs within a band of small, dense cells, which are deficient in smooth endoplasmic reticulum. The essential role of the fetal adrenal is to be able to secrete sufficient amounts of cortisol and aldosterone to permit survival immediately after parturition. The major factors that militate against the maintenance of appropriate free cortisol levels in utero include the inhibition of 3β-hydroxysteroid dehydrogenase activity by placental and intra-adrenal steroids and rapid placental and peripheral metabolism of cortisol to cortisone. The characteristic zonal morphology of the fetal cortex reflects a response to the necessarily high levels of plasma adrenocorticotropic hormone (ACTH), as a reduction in ACTH release is consistently followed by rapid adrenal involution. In the normal course of events, this occurs after parturition as the fetal zone becomes transformed to zona fasciculata. Neither the fetal pituitary nor the adrenal cortex possesses unique properties and functions; however, each is forced to perform its usual tasks in a somewhat difficult environment.

The adrenal cortex in the fetus and neonate

A new assay for the measurement of steroid 17alpha-hydroxylase activity in beef adrenals is described. This method is based on the biochemical mechanism of the enzymic reaction, i.e. the direct and stereospecific substitution of the proton located on the hydroxylated position. Progesterone or pregnenolone specifically labelled on the 17 position are solubilized in the incubation mixture with the help of Tween 80 and incubated under optimal conditions. The tritium enzymically released from the substrate is found in the medium as a molecule of water which is then distilled under reduced pressure and counted by liquid scintillation. The results obtained with this new method are comparable with those obtained with a conventional method using a 14C-labelled substrate.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1976.tb10042.x

New assay for pregnenolone and progesterone 17alpha- hydroxylase based on the specific substitution of a tritium situated on carbon 17.

The present study was designed to determine whether PRL, in addition to ACTH, stimulates adrenal secretion of dehydroepiandrosterone (DHA) in vivo at midgestation in the baboon fetus (Papio anubis). On day 100 of gestation (term = day 184), fetuses were exteriorized, and a constant infusion of saline (0.1 ml/min) was initiated via a fetal femoral vein. Forty minutes later, a bolus injection of 30 nmol ACTH/ml saline (n = 5), 40 nmol ovine PRL/ml saline (n = 4), or 1 ml saline (n = 5) was administered via the fetal femoral venous catheter. ACTH (0.15 nmol/min-0.1 ml saline), PRL (0.20 nmol/minO.l ml saline), or saline (0.1 ml/min) was then infused for an additional 25 min. Blood samples were obtained from the contralateral fetal femoral vein and the maternal saphenous vein immediately before and after peptide infusion and from the umbilical vein and artery at the end of the infusion. Fetal serum DHA concentrations (range, 9μ11 μg/100 ml) were significantly increased (P < 0.05) by PRL and ACTH, but not by s...

The Effects of Adrenocorticotropin and Prolactin on Adrenal Dehydroepiandrosterone Secretion in the Baboon Fetus

Publisher Summary This chapter describes steroidogenesis in the zones of the mammalian adrenal cortex By the microanatomy of the adrenal cortex, exemplified by those eutherian and metatherian species, it is clear that there are three major zones, namely, the zona glomerulosa, the zona fasciculata, and the zona reticularis with sub-divisions and additional zones Cells of organs are replaced throughout life, and the adrenal cortex is no exception; controversy lies in the mode whereby this is achieved Whatever may be the fact of the matter, the three zones produce various steroids in differing amounts and with both common and disparate controlling mechanisms The chapter discusses the receptor sites for ACTH and isolated cell studies It also discusses acute and chronic factors affecting secretion along with renin-angiotensin system, functional aspects of adrenocortical zonation, metatheria, adrenocortical sex steroids, and gonadotrophins

Steroidogenesis in the Zones of the Mammalian Adrenal Cortex

Patterns of steroid biosynthesis by human adrenals incubated in vitro with [7alpha-3H) pregnenolone: changes with (a) gestational age, (b) incubation period and (c) weight of incubated tissue.

Milner Aj

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Patterns of steroid biosynthesis by human adrenals incubated in vitro with [7alpha-3H) pregnenolone: changes with (a) gestational age, (b) incubation period and (c) weight of incubated tissue.