title: Metabolism of 20beta-hydroxy-4-pregnen-3-one in uterine tissue of non-pregnant rats in vitro.
abstract: In vitro experiments carried out with uterus preparations of ovariectomized adult rats indicate the presence in this tissue of a 20beta-hydroxy-steroid-oxidoreductase which catalyzes the conversion of 20beta-hydroxy-4-pregnen-3-one to progesterone. Since a hepatic 20beta-hydroxysteroid-oxidoreductase is absent in adult female rats, the myometrial enzyme can be responsible for the biological activity of 20beta-hydroxy-4-pregnen-3-one in these animals. Besides progesterone five metabolites were isolated and identified after incubation of [4-14C]20beta-hydroxy-4-pregnen-3-one with uterine tissue: 20beta-hydroxy-5alpha-pregnan-3-one, 20beta-hydroxy-5beta-pregnan-3-one, 5alpha-pregnane-3alpha,20beta-diol, 4-pregnene-3alpha,20beta-diol and 4-pregnene-3beta,20beta-diol. The conversion of 20beta-hydroxy-4-pregnen-3-one to progesterone permits us to regard all five steroids isolated as progesterone metabolites in the rat uterus. 20beta-hydroxy-5beta-pregnan-3-one is the first C21-metabolite with a 5beta(H)-configuration isolated in the rat uterus, which indicates the presence of 5beta-reductase in this tissue.
mesh_terms: D004092:20-alpha-Dihydroprogesterone / Q000378:metabolism*; D000818:Animals; D005260:Female; D007536:Isomerism; D011276:Pregnanediol / Q000096:biosynthesis; D011278:Pregnanes / Q000096:biosynthesis; D011280:Pregnanolone / Q000096:biosynthesis; D011283:Pregnenes / Q000096:biosynthesis; D011374:Progesterone / Q000031:analogs & derivatives* / Q000096:biosynthesis; D051381:Rats; D014599:Uterus / Q000378:metabolism*
chemical_list: D011278:Pregnanes; D011283:Pregnenes; D004092:20-alpha-Dihydroprogesterone; D011374:Progesterone; D011280:Pregnanolone; D011276:Pregnanediol