title: The effect of long-term treatment with steroid hormones or tamoxifen on oestrogen receptors (alpha and beta) in the endometrium of ovariectomized cynomolgus macaques.
abstract: The effects of oestrogen are mediated by two specific intracellular receptors, oestrogen receptors (ER) alpha and beta, which function as ligand-activated transcriptional regulators. Ovariectomized macaques (Macaca fascicularis) were used to study the regulation of ERalpha and ERbeta in the endometrium by immunohistochemistry and in situ hybridization after long-term hormone treatment. Animals were treated continuously for 35 Months with either conjugated equine oestrogen (CEE), medroxyprogesterone acetate (MPA), combined CEE/MPA, or tamoxifen (TAM). Treatment with CEE/MPA down-regulated ERalpha in the superficial glands. In the superficial stroma the ERalpha level was lower in the CEE/MPA group than in the CEE and MPA groups. ERbeta immunostaining was faint with minor variation in response to treatment, but increased in the superficial stroma after MPA treatment. The ratio of ERbeta/ERalpha increased in superficial stroma and gland after CEE/MPA treatment, and also in stroma after MPA and TAM. Cystic endometrial hyperplasia was observed in TAM-treated animals, in combination with a high level of ERalpha protein expression. The present data show that long-term hormone treatment affects the ERalpha and ERbeta protein levels in the endometrium. The balance between ERalpha and ERbeta seems to be important for the proliferative response to oestrogen.
authors.affiliation: Division for Reproductive Endocrinology, Department of Woman and Child Health, Karolinska Hospital, 17176 Stockholm, Sweden. Hong.Wang@ckb.ki.se
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: E
authors.initials: E
authors.lastname: Isaksson
authors.forename: B
authors.initials: B
authors.lastname: Von Schoultz
authors.forename: J M
authors.initials: JM
authors.lastname: Cline
authors.forename: L
authors.initials: L
authors.lastname: Sahlin
mesh_terms: D000818:Animals; D015536:Down-Regulation; D004717:Endometrium / Q000187:drug effects / Q000378:metabolism*; D004965:Estrogen Antagonists / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D015914:Estrogen Replacement Therapy; D004966:Estrogens, Conjugated (USP) / Q000494:pharmacology; D005260:Female; D008252:Macaca fascicularis; D008525:Medroxyprogesterone / Q000494:pharmacology; D023421:Models, Animal; D010052:Ovariectomy; D045167:Progesterone Congeners / Q000494:pharmacology; D011960:Receptors, Estrogen / Q000187:drug effects*; D013629:Tamoxifen / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D004965:Estrogen Antagonists; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004966:Estrogens, Conjugated (USP); D045167:Progesterone Congeners; D011960:Receptors, Estrogen; D013629:Tamoxifen; D008525:Medroxyprogesterone