title: Progesterone synthesis by human luteal cells: modulation by estradiol.
abstract: To assess the role of estradiol (E2) upon progesterone (P4) synthesis, a well defined human midluteal cell system was used. A dose-dependent inhibition of P4 synthesis with and without hCG was induced by E2. In addition, E2 had a dose related cumulative effect on pregnenolone as compared with control experiments (2-fold, P < 0.05) as well as in hCG-stimulated conditions (3-fold, P < 0.005). On the other hand, the concentrations of 20 alpha-hydroxyprogesterone obtained in all experimental conditions were similar to control values, indicating that the catabolism of P4 was not modified. 3 beta-Hydroxysteroid dehydrogenase activity was significantly diminished (P < 0.05) in the presence of E2. Finally, the kinetic studies on P4 synthesis from pregnenolone showed a competitive type of inhibition with a K1 of 2.22 x 10(-6) mol/L. These data indicate an inhibition of 3 beta-hydroxysteroid dehydrogenase on human corpus luteum by E2.
authors.affiliation: Department of Cell Biology and Genetics, School of Medicine, University of Chile, Santiago.
authors.forename: M
authors.initials: M
authors.lastname: Vega
authors.forename: L
authors.initials: L
authors.lastname: Devoto
authors.forename: O
authors.initials: O
authors.lastname: Castro
authors.forename: P
authors.initials: P
authors.lastname: Kohen
mesh_terms: D004092:20-alpha-Dihydroprogesterone / Q000378:metabolism; D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism; D000328:Adult; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000008:administration & dosage / Q000494:pharmacology; D003338:Corpus Luteum / Q000187:drug effects / Q000378:metabolism*; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007700:Kinetics; D011284:Pregnenolone / Q000096:biosynthesis; D011374:Progesterone / Q000096:biosynthesis*
chemical_list: D006063:Chorionic Gonadotropin; D003470:Culture Media; D004092:20-alpha-Dihydroprogesterone; D011374:Progesterone; D004958:Estradiol; D011284:Pregnenolone; D015096:3-Hydroxysteroid Dehydrogenases