Hypothalamic Thyroid Hormone Catabolism Acts as a Gatekeeper for the Seasonal Control of Body Weight and Reproduction

Perry Barrett, Francis J. P. Ebling, Sandrine Schuhler, Dana Lorraine Wilson, Alexander Ross, Amy Warner, Preeti Jethwa, Anita Boelen, Theo J. Visser, Daniel M. Ozanne, Zoe A. Archer, Julian Mercer, Peter John Morgan

Research output: Contribution to journalArticle

198 Citations (Scopus)

Abstract

Seasonal adaptations in physiology exhibited by many animals involve an interface between biological timing and specific neuroendocrine systems, but the molecular basis of this interface is unknown. In this study of Siberian hamsters, we show that the availability of thyroid hormone within the hypothalamus is a key determinant of seasonal transitions. The expression of the gene encoding type III deiodinase ( Dio3) and Dio3 activity in vivo ( catabolism of T-4 and T-3) is dynamically and temporally regulated by photoperiod, consistent with the loss of hypothalamic T3 concentrations under short photoperiods. Chronic replacement of T3 in the hypothalamus of male hamsters exposed to short photoperiods, thus bypassing synthetic or catabolic deiodinase enzymes located in cells of the ependyma of the third ventricle, prevented the onset of shortday physiology: hamsters maintained a long- day body weight phenotype and failed to undergo testicular and epididymal regression. However, pelage moult to a winter coat was not affected. Type II deiodinase gene expression was not regulated by photoperiod in these hamsters. Collectively, these data point to a pivotal role for hypothalamic DIO3 and T-3 catabolism in seasonal cycles of body weight and reproduction in mammals.

Original languageEnglish
Pages (from-to)3608-3617
Number of pages10
JournalEndocrinology
Volume148
Issue number8
Early online date3 May 2007
DOIs
Publication statusPublished - Aug 2007

Keywords

  • type-2 deiodinase gene
  • inactivating enzyme genes
  • photoperiodic regulation
  • phodopus-sungorus
  • Djungarian hamster
  • Siberian Hamsters
  • Pars Tuberalis
  • Melatonin Receptors
  • energy-balance
  • retinoic acid

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