Implicating a Temperature-Dependent Clock in the Regulation of Torpor Bout Duration in Classic Hibernation.
Fiche publication
Date publication
septembre 2018
Journal
Journal of biological rhythms
Auteurs
Membres identifiés du Cancéropôle Est :
Dr CIOCCA Dominique
Tous les auteurs :
Malan A, Ciocca D, Challet E, Pévet P
Lien Pubmed
Résumé
Syrian hamsters may present 2 types of torpor when exposed to ambient temperatures in the winter season, from 8°C to 22°C (short photoperiod). The first is daily torpor, which is controlled by the master circadian clock of the body, located in the SCN. In this paper, we show that daily torpor bout duration is unchanged over the 8°C to 22°C temperature range, as predicted from the thermal compensation of circadian clocks. These findings contrast with the second type of torpor: multi-day torpor or classic hibernation. In multi-day torpor, bout duration increases as temperature decreases, following Arrhenius thermodynamics. We found no evidence of hysteresis from metabolic inhibition and the process was thus reversible. As a confirmation, at any temperature, the arousal from multi-day torpor occurred at about the same subjective time given by this temperature-dependent clock. The temperature-dependent clock controls the reduced torpor metabolic rate while providing a reversible recovery of circadian synchronization on return to euthermy.
Mots clés
Arrhenius kinetics, circadian clock, daily torpor, hypothermia, temperature effects
Référence
J. Biol. Rhythms. 2018 Sep 7;:748730418797820