title: Gonadal steroid hormones upregulate medial preoptic mu-opioid receptors in the rat.
abstract: The density of mu-opioid receptors is dependent upon the levels of gonadal steroid hormones in the medial preoptic area of ovariectomized female rats. Because the region containing these cyclical mu-opioid receptors is relatively small, autoradiographic analysis of the binding of a saturating concentration of mu-selective radioligand was used to determine whether hormone treatment affects maximal binding capacity of these receptors. The results reveal that gonadal steroid hormones upregulate mu-opioid receptor binding capacity specifically in the medial preoptic area 27 h later, without affecting binding in adjacent brain regions. This suggests that hormones induce a functional increase of medial preoptic area mu-opioid receptors which could serve to regulate reproductive activities.
authors.affiliation: Department of Psychiatry, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: L
authors.initials: L
authors.lastname: Zhou
authors.forename: R P
authors.initials: RP
authors.lastname: Hammer
mesh_terms: D000818:Animals; D001345:Autoradiography; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000378:metabolism; D005260:Female; D012739:Gonadal Steroid Hormones / Q000378:metabolism / Q000494:pharmacology*; D011301:Preoptic Area / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure*; D011374:Progesterone / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000187:drug effects / Q000378:metabolism*; D013256:Steroids / Q000378:metabolism / Q000494:pharmacology; D014316:Tritium; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D004745:Enkephalins; D012739:Gonadal Steroid Hormones; D017450:Receptors, Opioid, mu; D013256:Steroids; D014316:Tritium; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D011374:Progesterone