title: A possible role of progesterone receptor in mouse oocyte in vitro fertilization regulated by norethisterone and its reduced metabolite.
abstract: BACKGROUND
  The contraceptive effect of the progestogen norethisterone (NET) and its main metabolites 5alpha-NET and 3beta,5alpha-NET has been demonstrated in several species, and most studies have focused on the effects of these compounds in the uterus. We previously reported that 5alpha-NET inhibits the progesterone (P(4))-induced acrosome reaction in pig and mouse spermatozoa and induces severe morphological damage in two-cell fertilized mouse oocytes.
  
  
  METHODS
  The main goal of this study was to analyze the possible role of P(4) receptor (PR) in the effects of NET and 5alpha-NET on the oocyte fertilization process. Different steroid treatments were used with or without cumulus-enclosed oocytes.
  
  
  RESULTS
  It was demonstrated that NET increases the percentage of fertilized oocytes in the same manner as P(4) does, while 5alpha-NET reduces the percentage of fertilized oocytes. This effect was not reversed by P(4) in the same concentrations.
  
  
  CONCLUSIONS
  A possible molecular mechanism for the effects of 5alpha-NET may be through a PR localized in the oocyte plasma membrane.
authors.affiliation: Departamento de Investigación Biomédica, Instituto Nacional de Perinatología, Isidro Espinoza de los Reyes, Mexico City 11000, Mexico. floresh8@yahoo.com
authors.forename: Héctor
authors.initials: H
authors.lastname: Flores-Herrera
authors.forename: Paola
authors.initials: P
authors.lastname: Díaz-Cervantes
authors.forename: Gustavo
authors.initials: G
authors.lastname: De la Mora
authors.forename: Verónica
authors.initials: V
authors.lastname: Zaga-Clavellina
authors.forename: Felipe
authors.initials: F
authors.lastname: Uribe-Salas
authors.forename: Ivone
authors.initials: I
authors.lastname: Castro
mesh_terms: D020101:Acrosome Reaction; D000818:Animals; D003280:Contraceptives, Oral, Synthetic / Q000494:pharmacology*; D005260:Female; D005306:Fertilization / Q000187:drug effects* / Q000502:physiology; D005307:Fertilization in Vitro; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009640:Norethindrone / Q000031:analogs & derivatives / Q000494:pharmacology*; D009865:Oocytes / Q000378:metabolism*; D011897:Random Allocation; D011980:Receptors, Progesterone / Q000187:drug effects* / Q000378:metabolism
chemical_list: D003280:Contraceptives, Oral, Synthetic; D011980:Receptors, Progesterone; D009640:Norethindrone