title: Effects of ovarian hormones on brain opioid binding sites in castrated female rats.
abstract: These experiments were performed to analyze whether treatments of ovariectomized female rats with ovarian steroid regimens able to induce either an increase (positive feedback effect) or a decrease (negative feedback effect) of serum levels of luteinizing hormone (LH) have some impact on the characteristics of mu-opioid binding sites in circumscribed areas of the brain. The increase of serum levels of LH elicited by a treatment with estradiol benzoate (EB) plus progesterone (P; positive feedback effect) was accompanied by a significant decrease in the number of mu-binding sites in the hypothalamus and in the corpus striatum. The decrease in serum levels of LH induced by a treatment with EB alone (negative feedback effect) brought about a significant increase of the number of mu-binding sites in the thalamus and in the hippocampus. These results seem to suggest that the release of LH induced by EB plus P may involve a decrease of hypothalamic mu-binding sites. Apparently, the inhibitory effect on LH release exerted by EB alone does not involve any change of the density of these binding sites in the hypothalamus.
authors.affiliation: Department of Endocrinology, University of Milano, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Dondi
authors.forename: P
authors.initials: P
authors.lastname: Limonta
authors.forename: R
authors.initials: R
authors.lastname: Maggi
authors.forename: F
authors.initials: F
authors.lastname: Piva
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D004723:Endorphins / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000378:metabolism
chemical_list: D004723:Endorphins; D017450:Receptors, Opioid, mu; D011374:Progesterone; D004958:Estradiol