When Oxygen Runs Low, the Naked Mole-Rat Finds a Way

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Contrary to what conventional beauty standards may lead us to believe, naked mole rats are good. As a result, the air in these confined, packed spaces is often low in oxygen and high in carbon dioxide. They're ruled by a loyal queen. They also wallow in excrement gathered at a communal toilet, presumably to give the colony averaging 80 members a common identifying odor.

But naked mole rats just carry on as normal.

To find out just how little oxygen they need, Thomas Park, a neuroscientist at the University of IL in Chicago, and Gary Lewin, a physiologist at the Max Delbrück Center for Molecular Medicine in Berlin, put naked mole rats and mice in a chamber with no oxygen.

Naked mole rats manage to avoid total glycolysis shutdown and death by pumping fructose into their cells during oxygen crises. People pass out after a breath or two of pure nitrogen, and would probably die in under 10 minutes. The discovery could have implications for humans during times of extreme oxygen deprivation, for example during a heart attack or stroke.

The report was published April 20 in Science.

"This is just the latest remarkable discovery about the naked mole-rat - a cold-blooded mammal that lives decades longer than other rodents, rarely gets cancer, and doesn't feel many types of pain", says Thomas Park, professor of biological sciences at the University of IL at Chicago, who led an worldwide team of researchers from UIC, the Max Delbrück Institute in Berlin and the University of Pretoria in South Africa on the study. No ATP means that cells eventually run out of energy and die, killing the organism in the process.

And that's exactly what naked mole rats do: they release fructose into their bloodstream when oxygen drops too low, and the sugar is taken up by heart and brain cells to keep critical systems running. "It's not as effective as the glucose pathway, but the trick is, it works without oxygen".

The naked mole rats, however, survived for at least 18 minutes. The researchers were stunned by how seemingly chill these little guys were in literally dire conditions.

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"We put them into the atmosphere chamber, which was primed at five percent oxygen, and we were ready to pull them out because they're valuable animals and we didn't want to just off them", Park explained. "They were still walking around, having a good old time".

For millions of years, naked mole rats have lived in large underground colonies, mainly located in central-east Africa. Yet they have some of nature's most incredible traits. A particularly powerful adaptation is their ability to turn on this fructose pathway that Park and his team have illuminated. Not so for the naked mole rats.

"The downside of this organization is all these animals living together in an unventilated tunnel system use up all the oxygen", Park said. "And the naked mole-rats surprised everybody, I think".

Coming to give you a kiss. By further studying the fructose pathway in naked mole rats, we could maybe develop technology inspired by their biology to help humans sustain themselves longer.

When a person has a heart attack, there is a small window of time to get the person resuscitated to get oxygen back to the brain, Park said.

Certain prejudices have prevented us from learning more about these creatures, mainly because some consider them mind-numbingly ugly. "No problems", Park says. "The most misunderstood thing is that they're ugly". "I'd say joint top with resistance to cancer".

There's a lot more that humans could learn about naked mole rats besides their biology. A small number of animals digging in random directions would starve before they found one.

"This is an exceptional feat for a mammal", says Grant McClelland, a comparative exercise physiologist at McMaster University in Hamilton, Canada, who was not involved in the work.

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