Vasoactive intestinal peptide and its role in continuous and seasonal reproduction in birds

Sunantha Kosonsiriluk, Natagarn Sartsoongnoen, Orn anong Chaiyachet, Nattiya Prakobsaeng, Thaweesak Songserm, Israel Rozenboim, Mohamed El Halawani, Yupaporn Chaiseha*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Native Thai chicken, an equatorial species breeds throughout the year, whereas turkeys are seasonal temperate zone breeder whose reproductive cycle is terminated by the onset of photorefractoriness. This study investigated VIPergic activity throughout a reproductive cycle in both species, hypothesizing that the differential expression of vasoactive intestinal peptide (VIP) would provide an insight into the differing reproductive strategies of the two species. Distribution of VIP neurons in the native Thai chicken and a comparison of VIPergic activity in the nucleus inferioris hypothalami (IH) and nucleus infundibuli hypothalami (IN) were investigated. VIP immunoreactivity was found throughout the native Thai chicken brain, predominantly located within the IH-IN. The pattern of VIP distribution in the native Thai chicken supports the findings reported in temperate zone species. Unlike the turkey, where there is a dissociation between VIPergic activity and prolactin levels during photorefractoriness, in the native Thai chicken, which do not express photorefractoriness, changes in VIP immunoreactive (VIP-ir) neurons within the IH-IN were directly correlated with prolactin throughout the reproductive cycle. VIPergic activity reached its lowest level after hatching of the chicks in the native Thai chicken, while in the turkey VIPergic activity was lowest only after exposure to a short day photoperiod and the acquisition of photosensitivity. This suggests that VIP neurons in the IH-IN may play a pivotal role in regulating the reproductive cycle and its differential expression following hatching of the young may, in part, account for the difference in reproductive mode between equatorial, continually breeding, non-photoperiodic birds and seasonally breeding, photoperiodic birds.

Original languageAmerican English
Pages (from-to)88-97
Number of pages10
JournalGeneral and Comparative Endocrinology
Issue number1
StatePublished - Oct 2008

Bibliographical note

Funding Information:
The authors acknowledge the financial support from the Thailand Research Fund (TRF) through the Royal Golden Jubilee (RGJ) Ph.D. program (Grant No. PHD/0226/2544 to S.K. and Y.C.), the TRF (Grant No. RSA4780001 to Y.C.), and the Research and Development Grant of Suranaree University of Technology to Y.C. The authors are grateful to University Farm of Suranaree University of Technology for providing the chicken barns.


  • Equatorial birds
  • Immunohistochemistry
  • Native Thai chicken
  • Photoperiod
  • Photorefractory
  • Turkey
  • Vasoactive intestinal peptide


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