Small underground rodents, with wrinkled skin and almost no hair, the shaved rats or naked mole rats (heterocephalus glaber) are as difficult as they are strange. Not only do they tolerate pain, they outgrow cancer, they live to be about 30 years old, but they are also able to go without oxygen. up to 18 minutes.
Shaved rats 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) discovered how this mammal can save energy in hypoxia – reducing its metabolic rate by up to 85% – and survive in low oxygen conditions. 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 blood and whose body temperature varied depending on the environment, thermoregular or produce heat, an activity that requires a lot of energy, while experiencing the oxygen deficiency, in which case saving energy is essential for survival.
“We wanted to know how they compensate thermoregulation and energy savings in hypoxia. We found that they turn off thermogenesis without the shivers (in mitochondrial brown adipose tissue) very quickly through a new mechanism”, he explains Matthew Pamenter, associate professor in the Department of Biology at the Canadian university and director of the Pamenter laboratory.
The data therefore shows that they not only actively generate heat, but can modulate that generation very quickly in the event of 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. The 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 is therefore the main source of heat generated by cold-free thermogenesis. Image B: the same animal in hypoxia. The animal’s color is darker and very close to the background color, indicating that its body temperature has basically dropped to room temperature (or slightly above). / Matthew Pamenter
A unique mechanism
The procedure by which these African mammals tolerate hypoxia – related to many human-related pathologies such as ictus or the chronic lung diseases – sheds light on how nature solved the problem of oxygen starvation tolerance, the study says. To live without it the key is hypometabolism, or reducing energy usage.
The procedure by which these African mammals tolerate hypoxia sheds light on how nature solved the problem of tolerance to oxygen starvation.
Scientists have discovered a mechanism that consists in the rapid elimination of the uncoupling protein (UCP1) from the cells of the brown adipose tissue intrascapularis. “Rats can do this within an hour of exposure to moderate hypoxia, whereas in other small rodents the reduction in UCP1 takes more than three days. This is an important step towards 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 scholarship National Geographic Explorers, to collect tissues from other species of mole rats used in this study, in collaboration with Nigel BennettA researcher at the University of Pretoria in South Africa, the team found that a similar rapid shift in UCP1 occurs with exposure to hypoxia in these animals as well.
However, this does not occur in a solitary species. “This suggests that this response may be driven by social structure of the colony in small rodents (the naked mole rat is a eusocial species, like bees and ants) ”, adds the scientist.
Hang Cheng, et al. “The thermogenesis of brown fat in the naked mole rat is decreased during hypoxia through a rapid decrease in UCP1” Nature Communications
Rights: Creative Commons.