title: Estrogen-induced guinea pig model for uterine leiomyomas: do the ovaries protect?
abstract: A guinea pig model was used to study the hormonal control of uterine leiomyomas. Twenty female guinea pigs were divided into four groups--young, old, ovariectomized (OVX), and non-OVX animals--and were given two estradiol-17 beta (E2) silastic implants each for 3-10 mo; another four older OVX animals served as controls and received empty implants. After 3 mo, 100% (8 of 8) of the OVX animals, but none of the OVX controls, developed tumors, mainly on the uterine serosa and the abdominal wall. Electron microscopy and desmin immunostaining demonstrated that the tumors were leiomyomas. In E2-treated animals, E2 levels in serum, leiomyomas, or leiomyoma-free uterine segments rose significantly while serum progesterone (P4) was negligible. Surprisingly, only 8% (1 of 12) of the non-OVX animals developed a tumor. This apparent "ovarian protection" was transient: after 6-9 mo, 50% of the remaining non-OVX animals developed leiomyomas, but these were smaller and fewer than in OVX animals. On the basis of this model, we propose the hypothesis that some factors from the ovaries suppress leiomyoma growth in response to estrogen but that as the ovaries age this protection is diminished, allowing the clinical development of leiomyomas.
authors.affiliation: Department of Obstetrics and Gynecology, University of South Florida, Tampa 33606, USA.
authors.forename: K B
authors.initials: KB
authors.lastname: Porter
authors.forename: J C
authors.initials: JC
authors.lastname: Tsibris
authors.forename: S V
authors.initials: SV
authors.lastname: Nicosia
authors.forename: J M
authors.initials: JM
authors.lastname: Murphy
authors.forename: W F
authors.initials: WF
authors.lastname: O'Brien
authors.forename: P S
authors.initials: PS
authors.lastname: Rao
authors.forename: W N
authors.initials: WN
authors.lastname: Spellacy
mesh_terms: D000818:Animals; D003893:Desmin / Q000032:analysis; D004343:Drug Implants; D004958:Estradiol / Q000097:blood / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D007150:Immunohistochemistry; D007889:Leiomyoma / Q000139:chemically induced* / Q000378:metabolism; D008854:Microscopy, Electron; D010052:Ovariectomy; D010053:Ovary / Q000502:physiology*; D011374:Progesterone / Q000097:blood; D014594:Uterine Neoplasms / Q000139:chemically induced* / Q000378:metabolism
chemical_list: D003893:Desmin; D004343:Drug Implants; D011374:Progesterone; D004958:Estradiol