title: Possible function of 17 beta-hydroxysteroid dehydrogenase in preimplantation hamster embryos.
abstract: 17 beta-Hydroxysteroid dehydrogenase (17 beta-HSD) catalyzes the interconversion of estradiol-17 beta (E2) and estrone (E1). The present study is designed to investigate the following: (1) the developmental stage of hamster embryos at which 17 beta-HSD activity first becomes detectable, and (2) the E1----E2 and E2----E1 conversion rate in the preimplantation hamster embryo. Embryos obtained from superovulated hamsters on days 1-4 were cultured in medium containing 107 ng [3H]E1 or -E2/ml and the respective conversion product, [3H]E2 or -E1, was isolated and assayed. The results show that (1) E1----E2 conversion was active in all embryos at the rate of 0.57, 0.66, 0.54 and 0.48 fmol/embryo/hr for day 1 (one-cell), 2 (two-cell), 3 (eight-cell) and 4 (blastocyst), respectively, and (2) E2----E1 conversion was not detectable in hamster embryos. In long-term blastocyst culture, E2----E1 conversion becomes detectable at 25 hours and increases sharply from 25 to 47 hours. These results suggest that (1) 17 beta-HSD may function mainly to convert E1 into E2 in preimplantation hamster embryos and (2) E2----E1 conversion may become active only during and after implantation.
authors.forename: J T
authors.initials: JT
authors.lastname: Wu
authors.forename: P S
authors.initials: PS
authors.lastname: Matsumoto
mesh_terms: D015067:17-Hydroxysteroid Dehydrogenases / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D001755:Blastocyst / Q000201:enzymology*; D006224:Cricetinae / Q000196:embryology*; D004958:Estradiol / Q000378:metabolism; D004970:Estrone / Q000378:metabolism; D008647:Mesocricetus
chemical_list: D004970:Estrone; D004958:Estradiol; D015067:17-Hydroxysteroid Dehydrogenases; C032690:3-alpha-(17-beta)-hydroxysteroid dehydrogenase (NAD(+))