Histamine H3 Receptor and Orexin A Expression During Daily Torpor in the Djungarian Hamster (Phodopus sungorus)

Annika Herwig, E. A. Ivanova, H. Lydon, Perry Barrett, S. Steinlechner, A. S. Loudon

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Seasonal animals use different strategies to reduce energy expenditure in the face of reduced seasonal food availability. For example, the ground squirrel enters a hibernation state with reduced metabolism, hypothermia and suppressed central nervous system activity, whereas the Djungarian hamster (Phodopus sungorus) employs daily bouts of torpor associated with reduced body temperature and energy expenditure. Studies in the hibernating ground squirrel implicate an increase in histamine synthesis and histamine H-3 receptor expression in the brain as a central mechanism governing hibernation. In the present study, we demonstrate an up-regulation of H-3 receptors in several brain nuclei in the Djungarian hamster during bouts of daily torpor, a shallow form of hypothermia, suggesting that histaminergic pathways may play a general role in maintaining low body temperature and torpor state in mammals. These regions include the arcuate nucleus, dorsomedial hypothalamus, suprachiasmatic nucleus, dorsal lateral geniculate nucleus and tuberomammilary nucleus. Interestingly, expression of the mRNA for orexins, a group of neuropeptides that increase wakefulness, remains unchanged during the arousal from daily torpor, suggesting that this classic 'arousal' pathway is not involved in the transition from a hypothermic to the euthermic state.

Original languageEnglish
Pages (from-to)1001-1007
Number of pages7
JournalJournal of Neuroendocrinology
Volume19
Issue number12
Early online date5 Oct 2007
DOIs
Publication statusPublished - Dec 2007

Keywords

  • H3R
  • daily torpor
  • phodopus
  • orexin
  • retinal ganglion-cells
  • dorsomedial hypothalamus
  • Siberian hamster
  • ground-squirrels
  • arcuate nucleus
  • brain histamine
  • gene-expression
  • hibernation
  • rats
  • nerons

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