A research group led by Tetsu Nakagawa (doctoral course student) at Hokkaido University Graduate School found that in Syrian hamsters, which are hibernating animals, when they experience hibernation, their diurnal rhythm of body temperature becomes summer-like.These results suggest that hibernation has an aspect that facilitates adaptation to the active period after awakening.
During the winter when food is scarce, hibernating animals go into a state of hypothermia to conserve energy, and in the spring they emerge from hibernation and become active.During hibernation, they stay in their burrows, where they do not receive light information that serves as seasonal indicators, so it was unclear how they adapt to environmental changes before and after hibernation.
The research group raised Syrian hamsters that had been raised in a warm summer environment with long days in a room with short days and cold winter conditions for a long period of time, and investigated changes in the diurnal rhythm of their body temperature.Syrian hamsters begin hibernation after spending several months in winter conditions, but after a certain period of time they end hibernation on their own.Through this series of processes, the diurnal rhythm of body temperature changed from a summer type to a winter type according to the surrounding environment, and then disappeared during the hibernation period.
However, after hibernation ended, the diurnal rhythm of body temperature returned to the summer pattern even though the surrounding environment was still winter, and then changed back to the winter pattern in response to the surrounding environment.On the other hand, the diurnal body temperature rhythm of Syrian hamsters, which did not hibernate even under a long-term winter-like environment, did not return to the summer pattern once it became winter-like.
These results suggest that Syrian hamsters begin hibernation with a winter-like body temperature rhythm adapted to the winter environment, and then spontaneously return to a summer-like body temperature rhythm and resume activity by the time hibernation ends. I understand.This study suggests that hibernation in mammals is a program that not only conserves energy during the winter, but also facilitates adaptation to the active period that follows awakening.
