Scientists succeed in inducing hibernation-like state in rodents

A team of Japanese scientists said they have succeeded in artificially inducing a hibernation-like state in rodents by stimulating nerve cells, suggesting beneficial implications for human medical applications and deep space exploration.

The University of Tsukuba and Riken, a state-run research institute, announced their discovery in the online edition of the scientific journal Nature.


Stimulation of the brain area, which puts warm-temperature animals into hibernation

Like the human brain, the mouse brain has many partitions, and different partitions have different functions. Studies have found that as long as a special stimulation is applied to a small area of the lower thalamus, the mouse will enter a low body temperature and low metabolism dormant state that lasts for several days, which is very similar to hibernation.


The method of stimulation is also very simple. It is to inject a drug called CNO into the vein of mice. Such a simple method can achieve such an amazing effect, which is amazing.


A detailed analysis showed that the set point of the body temperature (the body temperature under a certain constant temperature) of the mice in the dormant state was about 28 degrees, which was a full 9 degrees lower than the normal 37 degrees. This temperature can be considered as the body temperature that the mouse deliberately maintains in this state, just like the body temperature of the Siberian chipmunk during hibernation is 5 degrees.


Supplied photo shows a mouse in a normal state (L) and a mouse in a hibernation-like state. (Photo courtesy of University of Tsukuba)(Kyodo)


The study also found that when the outside temperature is lower than 28 degrees, dormant mice will curl up, muscle tremors and other behaviors. At the same time, the metabolism rate, which had been greatly slowed down, increased sharply in order to keep the body temperature above 20 degrees as much as possible.


This shows that even in the dormant state, experimental mice will maintain their body temperature at an appropriate level through a series of (perhaps unconscious) behaviors, and will not drop to a life-threatening level.


Since the temperature set points of hibernating animals are inherent characteristics formed during hundreds of millions of years of evolution, a higher set point means that the metabolic rate will not drop too much. Therefore, how to further reduce the body temperature set point of dormant animals, It is one of the focus of future research.


The researchers also tested the mice after the hibernation state was lifted, and found that their exercise ability and memory ability were not observably affected. The results of body anatomy also showed that there were no visible changes in their brain, heart, muscle and other tissues and organs.


What's more gratifying is that the same mouse can repeatedly switch between sleep and normal state, indicating that this sleep is reversible. This provides more possibilities for practical applications.


In addition to mice, researchers also did the same experiment on rabbits. The body weight of rabbits is 10 times that of mice, and there is no hibernation habit, but similar induction of hibernation has been observed in experiments.


Next, researchers will also set their sights on some more advanced species, including primates, to help us move towards our ultimate goal-human hibernation.


The research leader, Professor Takeshi Sakurai from the University of Tsukuba’s Department of Medicine, said, “We guess that, regardless of whether there is a hibernation habit, dormancy-inducing nerves are widely present in the mammalian brain. When there is an emergency such as food shortage or drug stimulation Under circumstances, their dormancy-inducing nerves may be activated." This is obviously of great significance to the survival challenges in some extreme situations.


[1]A discreteneuronal circuit induces a hibernation-like state in rodents

[2]Flipping theswitch on the thermoregulatory system

[3]「究極の省エネ」、人工冬眠 筑波大がスイッチ発見