Changing 17 beta-hydroxysteroid dehydrogenase activity in preimplantation rat and mouse embryos.
The 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity in rat and mouse preimplantation embryos was determined by measuring the interconversion of estradiol (E2) and estrone (E1). Rat and mouse embryos were cultured in medium containing 450 nM [3H]E1 or -E2 and the amount of [3H]E1 and -E2 in the medium at the end of the first hour was determined. The results showed that in both species 17 beta-HSD activity was detectable from the one-cell stage (Day 1) onward. In the rat, 17 beta-HSD effected primarily E2----E1 conversion, with the activity decreasing from Day 1 to Day 5. In the mouse, we found primarily E1----E2 conversion from Day 1 to the morning of Day 4, then E2----E1 increased sharply to near the E1----E2 rate in the evening of Day 4 and surpassed the E1----E2 rate the next morning. It seems that: 1) 17 beta-HSD is active throughout the entire preimplantation period, and 2) the enzyme activity changes during preimplantation development. Thus, the rat and mouse preimplantation embryo could regulate the E1- to -E2 ratio in the embryos and in their environment.
D015067:17-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D000818:Animals; D001755:Blastocyst / Q000201:enzymology* / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism; D004970:Estrone / Q000378:metabolism; D005260:Female; D005865:Gestational Age; D051379:Mice; D008815:Mice, Inbred Strains; D051381:Rats
D004970:Estrone; D004958:Estradiol; D015067:17-Hydroxysteroid Dehydrogenases