title: Metabolism of estrogens by rabbit blastocysts: formation of estrogen glucosides and preferential conversion of estrone to estradiol-17 beta.
abstract: When day 6 rabbit blastocysts were cultured (3 embryos/mL) in medium 199 containing 3.68 microM estradiol-17 beta (E2), 40% of E2 was metabolized in 24 h, at a rate of 18 pmol/embryo(b)/h, yielding 4 major metabolite fractions. Two of them were identified to be estrogen glucosides: 17 beta-hydroxyestra-1,3,5(10)-trien-3-yl beta-D-glucopyranoside (E(2)3G) (12 pmol/b/h) and 17-oxoestra-1,3,5(10)-trien-3-yl beta-D-glucopyranoside (E(1)3G) (0.5 pmol/b/h). If the blastocysts were cultured in 3.68 microM E1 medium, 75% of E1 was metabolized in 24 h (34.1 pmol/b/h); most of it appears as E2 (8 pmol/b/h), E(1)3G (16 pmol/b/h), and E(2)3G (6 pmol/b/h). Thus, the 17 beta-hydroxysteroid dehydrogenase activity in the rabbit blastocysts catalyzes mainly in the direction of the E1----E2 conversion, with little or no E2----E1. This may be responsible in part for the faster metabolism of E1 than E2 by the rabbit blastocyst. In comparison with the rat, mouse, and hamster blastocyst, the rabbit embryo shows an additional capability to conjugate large amounts of estrogens into glucosides by steroid glucosyltransferase.
authors.affiliation: Department of Obstetrics and Gynecology, University of Massachusetts Medical Center, Worcester 01655.
authors.forename: J T
authors.initials: JT
authors.lastname: Wu
authors.forename: K I
authors.initials: KI
authors.lastname: Williams
mesh_terms: D015067:17-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D000818:Animals; D001755:Blastocyst / Q000201:enzymology*; D002855:Chromatography, Thin Layer; D003460:Crystallization; D046508:Culture Techniques; D004958:Estradiol / Q000378:metabolism*; D004967:Estrogens / Q000378:metabolism*; D004970:Estrone / Q000378:metabolism; D005960:Glucosides / Q000096:biosynthesis*; D006027:Glycosides / Q000096:biosynthesis*; D006868:Hydrolysis; D011817:Rabbits
chemical_list: D004967:Estrogens; D005960:Glucosides; D006027:Glycosides; D004970:Estrone; D004958:Estradiol; D015067:17-Hydroxysteroid Dehydrogenases