title: Expression of hypothalamic GnRH-I mRNA in the female turkey at different reproductive states and following photostimulation.
abstract: In birds, changes in hypothalamic gonadotropin-releasing hormone-I (GnRH-I) content and release are correlated with reproductive stages. This study examined the distribution and expression level of GnRH-I mRNA in anatomically discrete hypothalamic nuclei throughout the turkey reproductive cycle and following photostimulation. GnRH-I mRNA expression was determined using in situ hybridization in non-photostimulated (NPS), egg-laying (LAY), incubating (INC) and photorefractory (REF) hens. Overall, GnRH-I mRNA expression was greatest in the nucleus commissurae pallii (nCPa) and around the organum vasculosum lamina terminalis (OVLT), with less expression observed in the nucleus septalis lateralis (SL), cortico-habenula cortico-septum area, and within the nucleus preopticus medialis. GnRH-I mRNA expression was significantly increased in nCPa, OVLT, and SL after NPS hens (6L:18D) were exposed to a 30 or 90 min pulse of light beginning 14 h after first light (dawn). GnRH-I mRNA abundance within nCPa, OVLT and SL was greater in LAY than in NPS and INC hens, while mRNA expression was least in REF hens. These results indicate that GnRH-I mRNA expression in birds is sensitive to light stimulation during the photosensitive period and can be used to more precisely characterize their different reproductive stages.
authors.affiliation: Department of Animal Science, University of Minnesota, 495 AnSci/Vet Med Bldg., 1988 Fitch Ave., St. Paul, MN 55108 ,USA.
authors.forename: Seong W
authors.initials: SW
authors.lastname: Kang
authors.forename: Aree
authors.initials: A
authors.lastname: Thayananuphat
authors.forename: Israel
authors.initials: I
authors.lastname: Rozenboim
authors.forename: James R
authors.initials: JR
authors.lastname: Millam
authors.forename: John A
authors.initials: JA
authors.lastname: Proudman
authors.forename: Mohamed E
authors.initials: ME
authors.lastname: El Halawani
mesh_terms: D000818:Animals; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D007031:Hypothalamus / Q000502:physiology; D010060:Ovulation; D017440:Photoperiod; D012333:RNA, Messenger / Q000096:biosynthesis; D014422:Turkeys / Q000502:physiology*
chemical_list: D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone