title: The circadian clock stops ticking during deep hibernation in the European hamster.
abstract: Hibernation is a fascinating, yet enigmatic, physiological phenomenon during which body temperature and metabolism are reduced to save energy. During the harsh season, this strategy allows substantial energy saving by reducing body temperature and metabolism. Accordingly, biological processes are considerably slowed down and reduced to a minimum. However, the persistence of a temperature-compensated, functional biological clock in hibernating mammals has long been debated. Here, we show that the master circadian clock no longer displays 24-h molecular oscillations in hibernating European hamsters. The clock genes Per1, Per2, and Bmal1 and the clock-controlled gene arginine vasopressin were constantly expressed in the suprachiasmatic nucleus during deep torpor, as assessed by radioactive in situ hybridization. Finally, the melatonin rhythm-generating enzyme, arylalkylamine N-acetyltransferase, whose rhythmic expression in the pineal gland is controlled by the master circadian clock, no longer exhibits day/night changes of expression but constantly elevated mRNA levels over 24 h. Overall, these data provide strong evidence that in the European hamster the molecular circadian clock is arrested during hibernation and stops delivering rhythmic output signals.
authors: Département de Neurobiologie des Rythmes, Institut des Neurosciences Cellulaires et Intégratives, Unité Mixte de Recherche 7168/LC2, Centre National de la Recherche Scientifique, Université Louis Pasteur, Strasbourg Cedex, France.
authors: Florent G
authors: FG
authors: Revel
authors: Annika
authors: A
authors: Herwig
authors: Marie-Laure
authors: ML
authors: Garidou
authors: Hugues
authors: H
authors: Dardente
authors: Jérôme S
authors: JS
authors: Menet
authors: Mireille
authors: M
authors: Masson-Pévet
authors: Valérie
authors: V
authors: Simonneaux
authors: Michel
authors: M
authors: Saboureau
authors: Paul
authors: P
authors: Pévet
mesh_terms: D000818:Animals; D056926:CLOCK Proteins; D002940:Circadian Rhythm / Q000502:physiology*; D006224:Cricetinae; D005060:Europe; D005786:Gene Expression Regulation; D006605:Hibernation / Q000502:physiology*; D013997:Time Factors; D015534:Trans-Activators / Q000235:genetics
chemical_list: D015534:Trans-Activators; D056926:CLOCK Proteins
references: J Comp Physiol B. 2001 Jun;171(5):431-9
references: 11497131
references: Annu Rev Physiol. 2004;66:275-89
references: 14977404
references: Proc Natl Acad Sci U S A. 2006 Dec 5;103(49):18775-80
references: 17121986
references: J Biol Rhythms. 2004 Oct;19(5):400-13
references: 15534320
references: J Comp Physiol B. 1994;163(8):690-8
references: 8195473
references: Comp Biochem Physiol A Comp Physiol. 1985;80(1):21-3
references: 2858288
references: J Neurosci. 1982 Feb;2(2):143-57
references: 6278102
references: Proc Natl Acad Sci U S A. 1989 Aug;86(16):6408-11
references: 2762331
references: Cell. 1999 Jan 8;96(1):57-68
references: 9989497
references: J Biol Rhythms. 2003 Aug;18(4):275-86
references: 12932080
references: Physiol Rev. 2003 Oct;83(4):1153-81
references: 14506303
references: Am J Physiol. 1984 Dec;247(6 Pt 2):R1062-6
references: 6507651
references: J Biol Rhythms. 2006 Dec;21(6):458-69
references: 17107936
references: Chronobiol Int. 2000 Mar;17(2):103-28
references: 10757457
references: Am J Physiol Regul Integr Comp Physiol. 2003 Apr;284(4):R1043-52
references: 12626365
references: J Comp Physiol B. 2002 Jan;172(1):47-58
references: 11824403
references: Neurosci Lett. 1994 Jan 3;165(1-2):117-21
references: 8015710
references: Sleep. 1993 Jun;16(4):372-86
references: 8341898
references: Am J Physiol. 1994 Apr;266(4 Pt 2):R1259-66
references: 8184970
references: Chronobiol Int. 2006;23(1-2):269-76
references: 16687300
references: J Comp Physiol B. 2002 Jan;172(1):59-70
references: 11828985
references: Nat Rev Genet. 2005 Jul;6(7):544-56
references: 15951747
references: J Exp Zool. 1986 Aug;239(2):247-54
references: 3746234
references: Annu Rev Physiol. 2004;66:239-74
references: 14977403
references: Am J Physiol. 1994 Apr;266(4 Pt 2):R1251-8
references: 8184969
references: J Comp Physiol B. 1995;165(3):171-82
references: 7665733