title: Serotonergic stimulation of prolactin secretion is inhibited by vasoactive intestinal peptide immunoneutralization in the turkey.
abstract: The neuronal mechanisms that govern prolactin (PRL) secretion in the turkey appear to involve monoaminergic systems. Considerable evidence indicates that serotonin (5-HT), acting centrally, is a potent stimulator of PRL secretion. This study, using birds actively immunized against VIP, tests the hypothesis that 5-HT stimulates PRL secretion by releasing vasoactive intestinal peptide (VIP). Nonimmunized turkeys were injected ip with saline, quipazine (5-HT agonist; 5 mg/kg), methysergide (5-HT antagonist; 8 mg/kg), or methysergide plus quipazine, and VIP-immunized birds were injected with saline or quipazine. Quipazine increased plasma PRL levels from 26.8 +/- 7.1 ng/ml at Time 0 to a peak value of 148.1 +/- 31.4 ng/ml 2 hr after infection. Pretreatment with methysergide or VIP-immunoneutralization abolished the PRL response to quipazine. Intraventricular infusion of 5-HT (1 nmol/min) caused plasma PRL to rise from a baseline of 16.3 +/- 2.6 ng/ml to 85.2 +/- 14.3 ng/ml after 30 min in nonimmunized control birds. Serotonin infusion did not induce PRL secretion in the VIP-immunized birds. These findings suggest that serotonergic stimulation of PRL secretion in the female turkey requires a functional VIPergic system.
authors.affiliation: Department of Animal Science, University of Minnesota, St. Paul 55108, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: el Halawani
authors.forename: O M
authors.initials: OM
authors.lastname: Youngren
authors.forename: I
authors.initials: I
authors.lastname: Rozenboim
authors.forename: G R
authors.initials: GR
authors.lastname: Pitts
authors.forename: J L
authors.initials: JL
authors.lastname: Silsby
authors.forename: R E
authors.initials: RE
authors.lastname: Phillips
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects; D005260:Female; D007114:Immunization; D007700:Kinetics; D008784:Methysergide / Q000494:pharmacology; D011388:Prolactin / Q000378:metabolism*; D011814:Quipazine / Q000494:pharmacology; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*; D014422:Turkeys; D014660:Vasoactive Intestinal Peptide / Q000276:immunology / Q000502:physiology*
chemical_list: D012701:Serotonin; D014660:Vasoactive Intestinal Peptide; D011814:Quipazine; D011388:Prolactin; D008784:Methysergide