Small underground rodents, with wrinkled skin and almost hairless, the shaved ratopines or naked mole rats ( Heterocephalus glaber ) are as hardy as they are strange. They not only tolerate pain, overcome cancer, live for about 30 years, but are also able to remain without oxygen for up to 18 minutes .
Shaved ratopines are heterothermic, that is, they are thermoregulated, but their internal temperature can also vary according to needs
Now, researchers from the University of Ottawa (Canada) have discovered how this mammal can save energy in case of hypoxia – reducing its metabolic rate by up to 85% – and survive in conditions low oxygen. The results are published in the journal Nature Communications .
For scientists it was a mystery to understand how these small rodents, which until now were considered cold-blooded and whose body temperature was believed to vary depending on the environment, were [19459002 ] thermoregulate or produce heat, an energy-intensive activity, while experiencing oxygen deficiency , in which case saving energy is essential for survival.
“We wanted to know how they compensate for thermoregulation and energy savings in hypoxia. We discovered that they deactivate chill-free thermogenesis (in mitochondrial brown adipose tissue ) very rapidly through a novel mechanism ”, explains Matthew Pamenter , associate professor of the department of Biology of the Canadian university and director of the Pamenter laboratory.
The data thus shows that they not only actively generate heat, but can modulate this generation very quickly in hypoxia. “Therefore, they are heterothermic , that is, they are thermoregulated, but their internal temperature can also vary according to needs,” emphasizes the researcher.
A: Naked mole rat in normoxia. Bright yellow / red / orange colors indicate that the region between the shoulder blades is the hottest part of the animal. This is where most of the brown adipose tissue is found and therefore the main source of heat generated by chill-free thermogenesis. Image B: The same animal in hypoxia. The animal is darker in color and very close to the background color, indicating that its body temperature has basically dropped to room temperature (or very slightly above). / Matthew Pamenter
A unique mechanism
The procedure by which these African mammals tolerate hypoxia – related to many human-related pathologies, such as [19459002 ] stroke or chronic lung disorders– sheds light on how nature has solved the problem of tolerance to oxygen starvation, the study says. The key to living without it is hypometabolism , or reducing energy use.
The procedure by which these African mammals tolerate hypoxia sheds light on how nature has solved the problem of tolerance to oxygen starvation
Scientists found a mechanism that involves rapid clearance of uncoupling protein (UCP1) from cells of intrascapular brown adipose tissue . “Rats can do it in one hour of exposure to moderate hypoxia, while in other small rodents the reduction of UCP1 takes more than three days. This is an important step in understanding how naked mole rats can save energy in hypoxia and survive in a hypoxic environment, ”says Pamenter.
On the other hand, after traveling to South Africa , with the support of a grant National Geographic Explorers , to collect tissues from other species of mole rats used in this study , in collaboration with Nigel Bennet , a researcher at the University of Pretoria in South Africa, the team found that a similar rapid change in UCP1 occurs with exposure to hypoxia in these animals as well.
However, it does not occur in a solitary species. “This suggests that this response may be driven by the social structure of the colony in small rodents (naked mole rats are an eusocial species, like bees and ants),” adds the scientist.
Hang Cheng, et al. “Naked mole-rat brown fat thermogenesis is diminished during hypoxia through a rapid decrease in UCP1” Nature Communications
Rights: Creative Commons.