title: Effect of mifepristone on steroid receptor expression and biotransformation of oestrogen and progesterone in rat uterus and deciduoma.
abstract: BACKGROUND
  [corrected] Mifepristone is a synthetic antiprogestin which terminates early pregnancy. Since it interferes with the progesterone maintained decidua, we compared the effect of mifepristone on oestrogen and progesterone receptors, and on the biotransformation of these hormones in normal and deciduous uterus.
  
  
  METHODS
  Ovariectomized rats were treated with an oestrogen-progesterone hormone regimen and deciduoma was induced by trauma in one horn of the rat uterus while the other served as a control under an identical hormonal milieu. Hormone receptor and biotransformation studies were done using radiolabelled oestradiol and progesterone with high specific activity.
  
  
  RESULTS
  The artificially formed decidual tissue was comparable with that of early pregnancy. Mifepristone replenished oestrogen and progesterone receptors which were suppressed by progesterone in both the normal and decidualized uterine horns. Inhibition of oestrogen receptors by progesterone correlated with decreased oestradiol levels at the site of action. Metabolism of progesterone to less potent compounds was promoted by mifepristone. The enzymatic activities of 17beta-hydroxysteroid dehydrogenase (which metabolizes oestradiol), and 20alpha-hydroxysteroid dehydrogenase and 5alpha-reductase (which metabolize progesterone) were altered by mifepristone.
  
  
  CONCLUSIONS
  The effect of mifepristone in varying the hormone receptor population and the availability of different levels of active metabolites of ovarian hormones have an Important role in the antiprogestin action of mifepristone.
authors.affiliation: All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India.
authors.forename: Urmila
authors.initials: U
authors.lastname: Vij
authors.forename: Anand
authors.initials: A
authors.lastname: Kumar
authors.forename: Kanhaiya
authors.initials: K
authors.lastname: Sharma
authors.forename: Mishi
authors.initials: M
authors.lastname: Kaushal
authors.forename: Raj
authors.initials: R
authors.lastname: Mehra
mesh_terms: D000021:Abortifacient Agents, Steroidal / Q000494:pharmacology*; D000818:Animals; D033301:Deciduoma / Q000187:drug effects*; D020847:Estrogen Receptor Modulators / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D015735:Mifepristone / Q000494:pharmacology*; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D011960:Receptors, Estrogen / Q000187:drug effects* / Q000378:metabolism; D011980:Receptors, Progesterone / Q000187:drug effects* / Q000378:metabolism; D014599:Uterus / Q000187:drug effects*
chemical_list: D000021:Abortifacient Agents, Steroidal; D020847:Estrogen Receptor Modulators; D004967:Estrogens; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D015735:Mifepristone; D011374:Progesterone