Somatostatin receptor activation is involved in the control of daily torpor in a seasonal mammal

Frank Scherbarth, Victoria Diedrich, Rebecca A Dumbell, Herbert A Schmid, Stephan Steinlechner, Perry Barrett

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17 Citations (Scopus)


Siberian hamsters (Phodopus sungorus) show spontaneous daily torpor only after ∼2 mo in winter-like short photoperiods (SP). Although some SP-induced hormonal changes have been demonstrated to be necessary for the occurrence of seasonal torpor, the whole set of preconditions is still unknown. Recent findings provide evidence that the hypothalamic pituitary growth axis is involved in endocrine responses to SP exposure in the photoperiodic hamsters. To examine whether suppression of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) secretion affects the incidence of daily torpor, we used two somatostatin receptor agonists, pasireotide (SOM230) and octreotide, with different affinity profiles for receptor subtypes. Pasireotide strikingly increased the torpor frequency in male hamsters compared with sham-treated controls, and torpor duration was often increased, which in some cases exceeded 12 h. In contrast, administration of octreotide reduced the body weight of SP hamsters but had only a marginal effect on torpor frequency in males and no effect in females. Together with measured concentrations of circulating IGF-1, the present results strongly suggest that reduced activity of the GH/IGF-1 axis is not critical for stimulation of torpor expression but activation of specific somatostatin receptors is critical. This putative role for certain somatostatin receptor subtypes in torpor induction provides a promising new approach to unravel the endocrine mechanisms of torpor regulation.

Original languageEnglish
Pages (from-to)R668-R674
Number of pages6
JournalAmerican Journal of Physiology-Regulatory Integrative and Comparative Physiology
Issue number6
Publication statusPublished - 15 Sept 2015

Bibliographical note

Copyright © 2015 the American Physiological Society.

We thank Dana Wilson at Rowett Institute for Nutrition and Health and Siegried Hilken at University of Veterinary Medicine Hannover for excellent technical support. We are also grateful to Thomas Ruf for generously lending the RFID reader to us. We also thank the two anonymous reviewers for helpful comments.


  • GH/IGF-1 axis
  • somatostatin receptors
  • torpor
  • seasonality
  • pasireotide (SOM230)
  • octreotide


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