title: Differential roles of hypothalamic serotonin receptor subtypes in the regulation of prolactin secretion in the turkey hen.
abstract: In the turkey, exogenous serotonin (5-hydroxytryptamine, 5-HT) increases prolactin (PRL) secretion by acting through the dopaminergic (DAergic) system. In the present study, infusion of the 5-HT(2C) receptor agonist, (R)(-)-DOI hydrochloride (DOI), into the third ventricle stimulates PRL secretion, whereas the 5-HT(1A) receptor agonist, (+/-)-8-OH-DPAT hydrobromide (DPAT), inhibits PRL secretion. Using the immediate-early gene, c-fos, as an indicator of neuronal activity, in situ hybridization histochemistry showed preferential c-fos co-localization within tyrosine hydroxylase immunoreactive neurons (the rate limiting enzyme in DA synthesis) in the areas of the nucleus preopticus medialis (POM) and the nucleus premammillaris (PMM), in response to DPAT and DOI, respectively. To clarify the involvement of 5-HT(1A) and 5-HT(2C) receptors in PRL regulation, their mRNA expression was determined on hypothalamic tissue sections from birds in different reproductive stages. A significant difference in 5-HT1A receptor was observed, with the POM of hypoprolactinemic short day and photorefractory birds showing the highest expression. 5-HT2C receptors mRNA did not change during the reproductive cycle. The data presented support the notion that DA neurons in the PMM and POM mediate the stimulatory and inhibitory effects of 5-HT, respectively, on PRL secretion and the 5-HTergic system can both stimulate and inhibit PRL secretion.
authors.affiliation: Department of Animal Science, University of Minnesota, St. Paul, MN, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bakken
authors.affiliation: Department of Animal Science, University of Minnesota, St. Paul, MN, USA.
authors.forename: Seong Wook
authors.initials: SW
authors.lastname: Kang
authors.affiliation: Department of Animal Science, University of Minnesota, St. Paul, MN, USA.
authors.forename: Sunantha
authors.initials: S
authors.lastname: Kosonsiriluk
authors.affiliation: Department of Animal Science, Tokyo University of Agriculture, Japan.
authors.forename: Takehito
authors.initials: T
authors.lastname: Kuwayama
authors.affiliation: School of Biology, Institute of Science, Suranaree University of Technology, Thailand. Electronic address: yupaporn@sut.ac.th.
authors.forename: Yupaporn
authors.initials: Y
authors.lastname: Chaiseha
authors.affiliation: Department of Animal Science, University of Minnesota, St. Paul, MN, USA.
authors.forename: Mohamed E
authors.initials: ME
authors.lastname: El Halawani
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000502:physiology*; D005260:Female; D015870:Gene Expression; D007031:Hypothalamus / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D044282:Receptor, Serotonin, 5-HT1A / Q000502:physiology*; D044405:Receptor, Serotonin, 5-HT2C / Q000502:physiology*; D055703:Reproductive Physiological Phenomena; D014422:Turkeys / Q000378:metabolism*
chemical_list: D030161:Avian Proteins; D044405:Receptor, Serotonin, 5-HT2C; D044282:Receptor, Serotonin, 5-HT1A; D011388:Prolactin
keywords: Birds; Dopamine; Prolactin; Serotonin receptor; Vasoactive intestinal peptide