title: Regulation of myometrial beta 2-adrenergic receptors by progesterone and estradiol-17 beta in late pregnant rats.
abstract: Rat myometrium exhibited a marked decrease in the concentration of beta 2-adrenergic receptors immediately before parturition, i.e., in the last 6 h of pregnancy. This phenomenon continued until the withdrawal of myometrial progesterone (-94% from Day 18 of pregnancy to term) and coincided with the sharp increase (+200%) of the myometrial concentration of estradiol. A linear positive correlation was found (r2 = 0.645) between the concentration of beta 2-adrenergic receptors and the log ratio of myometrial concentration of progesterone/myometrial concentration of estradiol (P/E2), suggesting a modulation of beta 2-adrenergic receptors by steroids. In rats with estrogen-dominated uteri (intact of ovariectomized late pregnant rats injected with estradiol), there was no change either in concentration or affinity of beta 2-adrenergic receptors relative to untreated control pregnant rats. In contrast, rats with progesterone-dominated uteri (intact or ovariectomized late pregnant rats treated with progesterone or ovariectomized rats) have an increased number of beta 2-adrenergic receptors, with a decreased affinity of these receptors compared to untreated control pregnant rats or to estrogen-treated rats. These results suggest that progesterone regulates the number of beta 2-adrenergic receptors in myometrium of late pregnant rats. The mechanisms by which progesterone exerts this regulation remains to be elucidated.
authors.affiliation: Laboratoire de Physiologie de la Reproduction, C.N.R.S. U.A. 040555, Université Pierre et Marie Curie, Paris, France.
authors.forename: J P
authors.initials: JP
authors.lastname: Maltier
authors.forename: Y
authors.initials: Y
authors.lastname: Benghan-Eyene
authors.forename: C
authors.initials: C
authors.lastname: Legrand
mesh_terms: D000818:Animals; D004958:Estradiol / Q000032:analysis / Q000494:pharmacology / Q000502:physiology*; D005260:Female; D009215:Myometrium / Q000032:analysis / Q000378:metabolism*; D010052:Ovariectomy; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D011374:Progesterone / Q000032:analysis / Q000494:pharmacology / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D013997:Time Factors
chemical_list: D011943:Receptors, Adrenergic, beta; D011374:Progesterone; D004958:Estradiol