title: Role of estrogen receptor α and β in the induction of progesterone receptors in hypothalamic ventromedial neurons.
abstract: The estrogen induction of progesterone receptors (PRs) in the ventrolateral division of the hypothalamic ventromedial nucleus (VMNvl) is critical for the regulation of female sexual behavior. VMNvl neurons express PRs and both types of estrogen receptors (ERα and ERβ), and their sequential activation initiates the molecular mechanisms underlying sexual behavior. To assess the relative importance of each ER subtype in the induction of PRs, we have estimated the total number of PR-immunoreactive neurons and quantified the total amount of PR protein in the VMNvl of adult ovariectomized rats that were injected with either estradiol benzoate (EB) or the specific agonists of the ERα, propyl-pyrazole triol (PPT), and of the ERβ, diaryl-propionitrile (DPN), in different doses and schedules. The administration of EB and of PPT alone, but not of DPN alone, increased the total number of PR-immunoreactive neurons and PR protein levels. When the specific agonists were administered sequentially, the total number of PR-immunoreactive neurons also increased, particularly when PPT was administered before DPN. Conversely, the concomitant administration of PPT and DPN did not increase the number of PR-immunoreactive neurons. The observation that PPT increases the number of PR-immunoreactive neurons and the levels of PR protein far less than EB shows that the estradiol induction of PRs in the VMNvl does not involve solely the activation of the ERα and suggests that it might also implicate the activation of membrane receptors. The present results also show that ERβ activation averts the action of ERα in the induction of PRs.
authors.affiliation: Department of Anatomy, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal. sasusana@med.up.pt
authors.forename: S I
authors.initials: SI
authors.lastname: Sá
authors.forename: P A
authors.initials: PA
authors.lastname: Pereira
authors.forename: V
authors.initials: V
authors.lastname: Malikov
authors.forename: M D
authors.initials: MD
authors.lastname: Madeira
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives; D047628:Estrogen Receptor alpha / Q000819:agonists / Q000378:metabolism*; D047629:Estrogen Receptor beta / Q000819:agonists / Q000378:metabolism*; D005260:Female; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009570:Nitriles / Q000008:administration & dosage; D010636:Phenols; D011422:Propionates / Q000008:administration & dosage; D011720:Pyrazoles / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D011980:Receptors, Progesterone / Q000378:metabolism*; D014697:Ventromedial Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism*
chemical_list: C486182:2,3-bis(4-hydroxyphenyl)-propionitrile; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D009570:Nitriles; D010636:Phenols; D011422:Propionates; D011720:Pyrazoles; D011980:Receptors, Progesterone; C486184:4,4',4''-(4-propyl-((1)H)-pyrazole-1,3,5-triyl) tris-phenol; C074283:estradiol 3-benzoate; D004958:Estradiol