Spontaneous Daily Torpor Versus Fasting-Induced Torpor in the Djungarian Hamster (Phodopus sungorus): Two Sides of a Medal or Distinct Phenomena?

Abstract

During the winter months the Djungarian hamster, Phodopus sungorus, can enter spontaneous daily torpor (SDT) even in the presence of abundant food and at thermoneutral ambient temperature. This indicates that torpor is not only a response to energy shortage and that it has not only the well-known energy saving function. Here we summarise the hallmarks of SDT and compare it to the characteristics of fasting-induced torpor (FIT) in P. sungorus. Some obvious differences let us conclude that these are two forms of hypothermia and appear to be regulated by different control mechanisms. Additionally, recent evidences suggest that SDT, at least in the Djungarian hamsters, has benefits beyond the energetic advantages.