RFamide-Related Peptide and its Cognate Receptor in the Sheep: cDNA Cloning, mRNA Distribution in the Hypothalamus and the Effect of Photoperiod

H. Dardente, M. Birnie, G. A. Lincoln, D. G. Hazlerigg

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129 Citations (Scopus)


Photoperiodic responses enable animals to adapt their physiology to predictable patterns of seasonal environmental change. In mammals, this depends on pineal melatonin secretion and effects in the hypothalamus, but the cellular and molecular substrates of its action are poorly understood. The recent identification of a mammalian orthologue of the avian gonadotrophin-inhibitory hormone gene has led to interest in its possible involvement in seasonal breeding. In long-day breeding Syrian hamsters, hypothalamic RFamide-related peptide (RFRP) expression is increased by exposure to long photoperiod. Because, opposite to hamsters, sheep are short-day breeders, we predicted that a conserved role in mammalian reproductive activation would decrease RFRP expression in sheep under a long photoperiod. We cloned the ovine RFRP cDNA and examined its expression pattern in Soay sheep acclimated to a 16 : 8 h or 8 : 16 h light/dark cycle (LP and SP, respectively). RFRP was expressed widely in the sheep hypothalamus and increased modestly overall with exposure to LP. Interestingly, RFRP expression in the ependymal cells surrounding the base of the third ventricle was highly photoperiodic, with levels being undetectable in animals held on SP but consistently high under LP. These data are inconsistent with a conserved reproductive role for RFRP across mammals. Additionally, we cloned the ovine homologue of the cognate RFRP receptor, rfr-2 (NPFF1) and found localised expression in the suprachiasmatic nuclei and in the pars tuberalis. Taken together, these data strengthen the emerging view that interplay between ependymal cells and the pars tuberalis might be important for the seasonal timing system.

Original languageEnglish
Pages (from-to)1252-1259
Number of pages8
JournalJournal of Neuroendocrinology
Issue number11
Early online date22 Aug 2008
Publication statusPublished - Nov 2008


  • RFamide peptides
  • seasonal reproduction
  • photoperiod
  • pars tuberalis
  • G protein-coupled receptor
  • gonadotropin-inhibitory hormone
  • prolactin-releasing peptide
  • LPXRF-amide peptides
  • neuropeptide FF
  • expression
  • identification
  • localization
  • reproduction
  • family


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