| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
2 Sleep Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States
3 Pharmacology, Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
* To whom correspondence should be addressed. E-mail: tscammel{at}bidmc.harvard.edu.
Core body temperature (Tb) is influenced by many physiological factors, including behavioral state, locomotor activity, and biological rhythms. To determine the relative roles of these factors, we examined Tb in orexin knockout (KO) mice, which have a narcolepsy-like phenotype with severe sleep-wake fragmentation. Because orexin is released during wakefulness and is thought to promote heat production, we hypothesized that orexin KO mice would have lower Tb while awake. Surprisingly, Tb was the same in orexin KO mice and wild-type (WT) littermates during sustained wakefulness. Orexin KO mice had normal diurnal variations in Tb, but the ultradian rhythms of Tb, locomotor activity, and wakefulness were markedly reduced. During the first 15 min of spontaneous sleep, the Tb of WT mice decreased by 1.0°C, but Tb in orexin KO mice decreased only 0.4°C. Even during intense recovery sleep after 8 hr of sleep deprivation, the Tb of orexin KO mice remained 0.7°C higher than in WT mice. This blunted fall in Tb during sleep may be due to inadequate activation of heat loss mechanisms or sustained activity in heat-generating systems. These observations reveal an unexpected role for orexin in thermoregulation. In addition, because heat loss is an essential aspect of sleep, the blunted fall in Tb of orexin KO mice may provide an explanation for the fragmented sleep of narcolepsy.
This article has been cited by other articles:
|
|
 |
|
  T. C. Thannickal, Y.-Y. Lai, and J. M. Siegel Hypocretin (orexin) cell loss in Parkinson's disease Brain, June 1, 2007; 130(6): 1586 - 1595. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Zhang, J. M. Zeitzer, T. Sakurai, S. Nishino, and E. Mignot Sleep/wake fragmentation disrupts metabolism in a mouse model of narcolepsy J. Physiol., June 1, 2007; 581(2): 649 - 663. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. A. Romanovsky Thermoregulation: some concepts have changed. Functional architecture of the thermoregulatory system Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2007; 292(1): R37 - R46. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. B. Persson Temperature control: from molecular insights, regulation in king penguins and diving seals, to studies in humans Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2006; 291(3): R512 - R514. [Full Text] [PDF]
|
|
|
|
|
|
M. Szekely Orexins, energy balance, temperature, sleep-wake cycle Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2006; 291(3): R530 - R532. [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
