Suncus murinus as a novel model animal that is suitable for elucidating the mechanism of daily torpor

Torpor, a state of lowered body temperature due to active reduction of the metabolic rate, has potential medical benefits. The aim of this study was to establish a novel laboratory animal that enter torpor without imposing complex conditions. When house musk shrews (Suncus murinus) were kept at an ambient temperature of 24 degrees C, most of the animals did not enter daily torpor. However, when the ambient temperature was lowered to below 20 degrees C, all of the shrews showed torpor in the absence of fasting and short-day photoperiod. The shrews that were exposed to a stepwise decrease in ambient temperature from 24 degrees C to 8 degrees C entered torpor even after returning them to a room kept at 24 degrees C. In conclusion, this study indicates that Suncus murinus may be a suitable model animal for elucidating the mechanism of daily torpor. Elucidation of the mechanisms of torpor by using this model may be useful for inducing a state of artificial hibernation in various species including humans.