Topic
Pregnenolone
About: Pregnenolone is a research topic. Over the lifetime, 3539 publications have been published within this topic receiving 126444 citations. The topic is also known as: (3b)-3-hydroxy-Pregn-5-en-20-one & 3-Hydroxypregn-5-en-20-one.
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TL;DR: In human adult subcutaneous adipose tissue, there was no in vitro conversion of progesterone to testosterone and no aromatization of androstenedione or testosterone labeled with 14C was demonstrated.
Abstract: The uptake and metabolism of various steroids in adipose tissue have been studied using both in vitro and in vivo techniques. The in vitro uptake of progesterone and testosterone (60%) was found to be much higher than the uptake of cortisol and estriol (13%). In vivo, the uptake of testosterone, androstenedione, estrone and estradiol by the total adipose mass was much greater in obese patients than in non obese individuals. Estrone and estradiol were found to be interconvertible following incubation with human adipose tissue slices. In vitro, progesterone was metabolized to a variety of compounds with 20α-dihydroprogesterone4 being the major metabolite. No conversion of cholesterol or cholesterol sulfate to pregnenolone or pregnenolone sulfate could be demonstrated in the brown adipose tissue of a newborn infant. In human adult subcutaneous adipose tissue, there was no in vitro conversion of progesterone to testosterone and no aromatization of androstenedione or testosterone labeled with 14C was ...
81 citations
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TL;DR: The substrate specificity, nuclear localization, and tissue localization of SULT2B1b suggest a role in regulating the responsiveness of cells to adrenal androgens via their direct inactivation or by preventing their conversion to more potent androgens and estrogens.
80 citations
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TL;DR: The findings suggest that the presence of the 27HC biosynthesis pathway in adipocytes may represent a defense mechanism to prevent the formation of new fat cells upon overfeeding with dietary cholesterol.
80 citations
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TL;DR: Estrogen therapy in 10 postmenopausal women resulted in significant increases in the serum levels of 3 of the steroids compared to those in untreated subjects, confirming the postulate that ovarian estrogens stimulate the secretion of adrenal androgens.
80 citations
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TL;DR: A revised model of the fetoplacental steroidogenic unit is presented which may explain both normal and fetal hyperplasia and postnatal involution of the adrenal cortex and the variations from this pattern seen in apituitary children.
Abstract: The effect upon steroidogenesis of adding various steroids produced by the placenta was studied in short term cultures of human fetal adrenal cells. The addition of high concentrations (103 ng/ml) of estrone or estriol inhibited the production of cortisol, but only the former elicited a parallel increase in dehydroepiandrosterone (DHA) production. Estradiol was effective in inhibiting Δ4-3-ketosteroid production at concentrations of 10-100 ng/ml, levels which approach those found in the fetal circulation, while DHA production was increased at concentrations of 1 eg/ml. The addition of progesterone (4 eg/ml) to the medium caused increased production of cortisol and corticosterone, but had no effect on DHA production. Pregnenolone (4)eg/ml) increased the basal production of DHA and slightly impaired both basal and ACTH-stimulated aldosterone production, but had no effect on cortisol production. The data demonstrate that of the many fetal and placental factors which have been studied to date, only ACTH and e...
80 citations