title: Consequence of dynorphin-A administration on anterior pituitary hormone concentrations in the adult male rhesus monkey.
abstract: This study examines the role of dynorphin-A(1-13) and dynorphin-A(1-10)-amide in the neuroendocrine regulation of anterior pituitary hormones in nonrestrained, adult male rhesus monkeys. The effects of these opioids on plasma concentrations of prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyrotropin (TSH) and growth hormone (GH) were assessed. Intravenous administration of dynorphin-A(1-13), 1-120 micrograms/kg, significantly increased plasma PRL levels. Average maximal increases of 90-230% occurred within 5 min and levels remained significantly elevated for up to 120 min. PRL response reached a plateau following the 30 micrograms/kg dose. Dynorphin-A(1-13) had no observable effects on plasma concentrations of LH, FSH, TSH or GH at any dose level studied. Administration of dynorphin-A(1-10)-amide produced significant dose-dependent increases in plasma PRL concentrations. Dose levels of 1-120 micrograms/kg produced mean peak increases from 100 to 230%, 5-10 min postadministration. Dynorphin-A(1-10)-amide had no significant effect on plasma concentrations of LH, FSH, TSH or GH. The increases in plasma PRL concentrations induced by dynorphin-A were naloxone-reversible. These results indicate a selective effect of dynorphin-A on the regulatory mechanisms of PRL secretion over that of other anterior pituitary hormones.
mesh_terms: D000818:Animals; D004399:Dynorphins / Q000494:pharmacology*; D005640:Follicle Stimulating Hormone / Q000097:blood; D013006:Growth Hormone / Q000097:blood; D007986:Luteinizing Hormone / Q000097:blood; D008253:Macaca mulatta; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000187:drug effects; D010908:Pituitary Hormones, Anterior / Q000097:blood*; D011388:Prolactin / Q000097:blood; D013972:Thyrotropin / Q000097:blood
chemical_list: D010446:Peptide Fragments; D010908:Pituitary Hormones, Anterior; D009270:Naloxone; C026843:dynorphin (1-13); D004399:Dynorphins; C039666:dynorphin amide (1-10); D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013972:Thyrotropin; D013006:Growth Hormone