Expression of hypothalamic GnRH-I mRNA in the female turkey at different reproductive states and following photostimulation

Seong W. Kang, Aree Thayananuphat, Israel Rozenboim, James R. Millam, John A. Proudman, Mohamed E. El Halawani

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)86-94
Number of pages9
JournalGeneral and Comparative Endocrinology
Issue number2
StatePublished - Apr 2006


  • Avian hypothalamus
  • GnRH-I mRNA expression
  • In situ hybridization
  • Photostimulation
  • Turkey reproductive cycle


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