title: Effect of oral contraceptives on the rat brain and pituitary opioid peptides.
abstract: This study was designed to explore the hormonal regulation of CNS opioid peptide levels in female Sprague Dawley rats. Forty-eight animals were divided into 2 equal groups for acute and chronic studies. Each group was further divided into 4 subgroups, each containing 6 animals. Each rat in the control group received an inert pill (in 0.25 ml corn oil daily by gavage); the second group, 15 micrograms norethindrone (NE, a potent progestin present in the oral contraceptive Micronor); the third group, 15 micrograms NE and 1 microgram ethinyl estradiol, EE2 (present in the oral contraceptive Modicon) and the fourth group, 10 times the dose of the third group. Rats were treated either acutely for 5 days or chronically for 7 weeks. Opioid peptides were estimated by radioimmunoassay. Acute administration of 150 micrograms NE + 10 micrograms EE2 decreased the levels of methionine-enkephalin (ME), leucine-enkephalin (LE), dynorphin (DYN) and beta-endorphin like immunoreactivity (beta-EI) by about 50% in the pituitary. The same dose on chronic administration also decreased DYN, but increased the levels of ME and LE in the pituitary by 331 and 69%, respectively. In the hypothalamus, chronic administration of NE + EE2 increased the level of ME (155%) and LE (87%) as well as of DYN (97%). In the striatum, the levels of LE (33%) and DYN (115%) were elevated during chronic administration. It is concluded that the acute administration of NE + EE2, in general, reduces the levels of ME, LE, DYN and beta-EI.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.forename: G A
authors.initials: GA
authors.lastname: Tejwani
authors.forename: K K
authors.initials: KK
authors.lastname: Vaswani
authors.forename: J C
authors.initials: JC
authors.lastname: Barbacci
mesh_terms: D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D003276:Contraceptives, Oral / Q000494:pharmacology*; D003342:Corpus Striatum / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004399:Dynorphins / Q000378:metabolism; D004723:Endorphins / Q000378:metabolism*; D004743:Enkephalin, Leucine / Q000378:metabolism; D004744:Enkephalin, Methionine / Q000378:metabolism; D004997:Ethinyl Estradiol / Q000494:pharmacology; D005260:Female; D007031:Hypothalamus / Q000378:metabolism; D009640:Norethindrone / Q000494:pharmacology; D010902:Pituitary Gland / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D001615:beta-Endorphin
chemical_list: D003276:Contraceptives, Oral; D004723:Endorphins; D004997:Ethinyl Estradiol; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D001615:beta-Endorphin; D004399:Dynorphins; D009640:Norethindrone