title: Disparate actions of mifepristone (RU 486) on glands and stroma in the primate endometrium.
abstract: Besides being an antiprogestin, mifepristone (RU 486) was recently shown to antagonize oestrogen-dependent growth in the endometrium. To explore the molecular mechanisms for this phenomenon, we investigated whether or not the morphological effects of mifepristone are mediated by the progesterone receptor (PR) and whether mifepristone has disparate effects on the glandular epithelium and stroma. Six groups of hypogonadal, oestrogen-primed cynomolgus monkeys were treated for 2 weeks with: vehicle only (group I); mifepristone (group II); mifepristone plus progesterone at 0.2 mg/kg (group III), 1.0 mg/kg (group IV) or 5.0 mg/kg (group V); and progesterone only (5.0 mg/kg) (group VI). Histomorphological evaluation showed strikingly compacted stroma in the mifepristone-exposed endometria (group II), which was partially reversible by additional progesterone treatment (groups III-V). Glandular proliferation (pseudostratification, glandular mitoses) in mifepristone-treated monkeys was not significantly different from that in vehicle (oestradiol)-treated monkeys, but was inhibited by progesterone-only treatment. Cells containing vacuoles were scarce in the mifepristone-exposed endometrium, but detected frequently in progesterone-exposed endometria, indicating the strong antisecretory effect of mifepristone on glands. We conclude that oestrogen-dependent oedema in the stroma is antagonized by mifepristone. The reversal of this effect by progesterone suggests a PR-mediated mechanism. In glands, mifepristone is antiprogestogenic, but not antioestrogenic. Thus, stromal cells may be the target of antiprogestin-induced inhibition of oedema and endometrial growth.
authors.affiliation: Department of Obstetrics and Gynecology, University of Tübingen, Germany.
authors.forename: R R
authors.initials: RR
authors.lastname: Greb
authors.forename: L
authors.initials: L
authors.lastname: Kiesel
authors.forename: A K
authors.initials: AK
authors.lastname: Selbmann
authors.forename: M
authors.initials: M
authors.lastname: Wehrmann
authors.forename: G D
authors.initials: GD
authors.lastname: Hodgen
authors.forename: A L
authors.initials: AL
authors.lastname: Goodman
authors.forename: D
authors.initials: D
authors.lastname: Wallwiener
mesh_terms: D000818:Animals; D004338:Drug Combinations; D004487:Edema / Q000139:chemically induced / Q000473:pathology / Q000517:prevention & control; D004717:Endometrium / Q000187:drug effects*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D004958:Estradiol / Q000097:blood; D004967:Estrogens; D005260:Female; D006727:Hormone Antagonists / Q000494:pharmacology*; D008252:Macaca fascicularis; D015735:Mifepristone / Q000494:pharmacology*; D011374:Progesterone / Q000097:blood / Q000494:pharmacology; D017154:Stromal Cells / Q000187:drug effects / Q000378:metabolism; D014591:Uterine Diseases / Q000139:chemically induced / Q000473:pathology / Q000517:prevention & control
chemical_list: D004338:Drug Combinations; D004967:Estrogens; D006727:Hormone Antagonists; D015735:Mifepristone; D011374:Progesterone; D004958:Estradiol