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.

Epidermal growth factor directly stimulates steroidogenesis in primary cultures of porcine Leydig cells: actions and sites of action.

Abstract: The actions and the mechanisms of action of epidermal growth factor (EGF) in testicular steroidogenesis were investigated using a model of primary culture of purified porcine Leydig cells from immature intact animals EGF decreased (17-fold) human CG (hCG)-induced dehydroepiandrosterone (DHEA) accumulation in the medium whereas it enhanced (25- fold) that of testosterone The maximal and half-maximal effects on both DHEA and testosterone secretions were observed at similar concentrations which were, respectively, 3 (5 × 10-10 M) and 07 (11 × 10-11 M) ng/ml EGF, after 72-h treatment EGF effect on DHEA and testosterone secretion was similarly observed whether the cells were acutely (3 h) stimulated with hCG (1 ng/ml) or with 8-bromo-cAMP (10-3 M) TO further localize the steroidogenic biochemical steps affected by EGF, the growth factor action on steroidogenic enzyme activities was investigated EGF increased Δ5 steroid intermediate (ie pregnenolone and DHEA) formation [evaluated in the presence of 10

Molten Globule Structure and Steroidogenic Activity of N-218 MLN64 in Human Placental Mitochondria

Abstract: Progesterone synthesis by the human placenta requires the conversion of mitochondrial cholesterol to pregnenolone by cytochrome P450scc. Most steroidogenic tissues use the steroidogenic acute regulatory protein (StAR) to deliver cholesterol to the inner mitochondrial membrane where P450scc is located, but StAR is not expressed in the human placenta. However, the human placenta does express MLN64, which has a C-terminal domain homologous to StAR that can also transport cholesterol. We investigated the ability of bacterially expressed N-218 MLN64 and N-62 StAR to transport cholesterol between artificial membranes and to its inner membrane site of use in placental mitochondria. Urea denaturation experiments show that N-218 MLN64 undergoes a pH-dependent and denaturant-dependent structural transition to a molten globule state, as reported previously for N-62 StAR. N-218 MLN64 stimulated cholesterol transfer between artificial phospholipid vesicles with an initial rate of 6.5 mol/min·mol N-218 MLN64. Both N-21...

Stromal cells of the human postmenopausal ovary display a distinctive biochemical and molecular phenotype.

Abstract: The stroma of the human postmenopausal ovary is postulated to produce androgens, but evidence for and against this idea exits in the literature. The purpose of this study was to determine whether key steroidogenic enzymes involved in androgen synthesis are expressed in the postmenopausal ovarian stroma. Stromal cells were isolated from postmenopausal ovaries and expression for genes involved in steroidogenesis [steroidogenic acute regulatory protein (StAR), P450scc, 3β-hydroxysteroid dehydrogenase (3β-HSD) P450c17, and P450c27] as well as for several growth factor binding proteins [gremlin, IGF binding protein-4, follistatin, and secreted frizzled-related protein (sFRP)-1 and -4], were compared with cultured human theca cells and dermal fibroblasts. Production of steroids (pregnenolone, progesterone, and hydroxysterol metabolites) and the metabolism of [3H] pregnenolone by ovarian stromal cells were also assessed. Isolated ovarian stromal cells from different subjects had a uniform morphology within and a...