Small hibernating mammals such as chipmunks and dormouses repeatedly awaken during the winter months, called mid-hibernation, due to a hypothermia of 10 ° C or less and a rapid rewarming to around 37 ° C.
The mechanism is why hibernating mammals can tolerate such long-term low temperatures and rapid rewarming, even though they are fatal stresses for non-hibernating mammals such as humans and mice. Most are unknown.
This time, research groups at Hokkaido University and the University of Tokyo investigated the mechanism of low-temperature tolerance at the cellular level in Syrian hamsters, which are small hibernating mammals.As a result, it was found that Syrian hamsters exhibit low temperature tolerance by retaining high concentrations of vitamin E in the liver.
First, it was confirmed that the liver cells (hepatocytes) of Syrian hamsters have strong cold tolerance that can survive even at low temperatures where mouse hepatocytes would die.However, strangely, the cold tolerance of hepatocytes disappeared or appeared depending on the type of food given to the hamster.When the research group examined this difference, hepatocytes became cold-inducible when they were fed a diet low in the vitamin E type α-Tocopherol (αT) (although it did not affect survival under normal conditions). It was found to cause cell death.
On the other hand, in the case of mice, hepatocytes were not endowed with low temperature tolerance even when fed with a diet containing a large amount of αT.Therefore, when αT in hepatocytes and blood was compared, it was found that Syrian hamsters retain αT in hepatocytes and blood at a concentration 10 times higher than that in mice. αT is known to prevent lipid peroxidation, and from this, Syrian hamsters prevent lipid peroxidation and cell death associated with low temperature and rewarming by keeping the concentration of αT high in hepatocytes and blood. It was suggested that it may be.
The mechanism of low temperature tolerance clarified in this study is expected to be applied to the reduction of organ damage in transplantation medicine.
Paper information:[Communications Biology] Hepatic resistance to cold ferroptosis in a mammalian hibernator Syrian hamster depends on effective storage of diet-derived α-tocopherol
