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Naked Mole-Rats Bathe Their Bodies in Carbon Dioxide to Prevent Seizures

Expelled by animals as a waste product, the gas appears to play a crucial role in keeping these bizarre, burrowing rodents safe

Naked mole-rats pile on top of each other in large groups to sleep inside their nest. This behavior may help keep carbon dioxide levels high, lowering the animals' risk of seizure. (Roland Gockel)
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Pale, wrinkled, and hairless, the naked mole-rat looks more like a toothy, undercooked sausage than a paragon of mammalian health. But researchers have long known that these bizarre, burrowing rodents—which can live for decades, remarkably free of illness—guard some fascinating evolutionary secrets that help them shirk disease.

The latest find shows naked mole-rats have an unusual way of avoiding seizures: huddling so close to each other that they swaddle themselves in carbon dioxide, the gas produced when animals exhale. Seizures are caused by sudden fluctuations in brain activity, and carbon dioxide appears to tamp down naked mole-rat brain cells, according to a study published this week in Current Biology.

To be clear, naked mole-rats and humans are very different, and the researchers aren’t suggesting that other creatures should deprive themselves of air to maintain good health. But the rodents’ unusual behavior does seem to be tied to a genetic mutation that’s present in some seizure-prone people—a finding that could someday inform the development of live-saving therapies, according to a team of researchers led by the College of Staten Island’s Daniel McCloskey.

As Nina Pullano reports for Inverse, the study helps explain some of the weird tendencies of naked mole-rats, who tend to cluster up in tight heaps, even when there’s plenty of space to go around. “It seemed that no matter what we did to provide enrichment or comfort around their housing environment, they preferred to be piled on top of one another in a single cage,” McCloskey tells Inverse. “It was like building a luxury resort and having all of the guests choose to sleep in the same broom closet.”

McCloskey and his team tested the rodents’ response to different concentrations of gases: oxygen, which animals need to breathe, and carbon dioxide, a byproduct of respiration that builds up when many living bodies are packed together. In a counterintuitive twist, the naked mole-rats seemed to do best in low oxygen, high carbon dioxide conditions—but suffered seizures when the ratio was flipped, Nicoletta Lanese reports for Live Science.

When the researchers searched for a genetic explanation for the animals’ unanticipated need for carbon dioxide, they stumbled upon R952H, a mutation that makes it more difficult for naked mole-rats to keep their brain activity to a minimum, and leaving them constantly on the brink of seizing.

To protect themselves, the rodents seem to have evolved a way to leverage the natural properties of carbon dioxide—a gas that’s “really good at calming the brain down, if not shutting the brain down,” McCloskey tells Live Science. In naked mole-rats, carbon dioxide slowed runaway brain activity, keeping them calm and safe when they kept each other close.

Carbon dioxide is normally considered a waste product—the stuff our bodies want to get rid of after we’ve inhaled and processed the oxygen that’s vital for survival. But naked mole-rats have taken a chemical “that we usually consider to be bad and [are] using it for good,” Thomas Park, Thomas Park, a biologist at the University of Illinois at Chicago who wasn’t involved in the study, tells Live Science.

The R952H mutation has also been found in people with certain neurological conditions, including autism spectrum disorder, epilepsy, and schizophrenia, according to a statement. Though the study’s findings can’t translate directly to humans, they suggest that certain individuals may be more sensitive to air—and may benefit from certain respiratory therapies. According to Live Science, researchers have previously shown that quick hits of carbon dioxide can actually suppress seizures in some epilepsy patients.

Still, naked mole-rats remain some of nature’s biggest weirdos, and could be using other tactics to keep seizures and other health issues at bay. Carbon dioxide may play an important role in their survival, but it’s unlikely to be any kind of silver bullet, even for the healthiest of rodents. As McCloskey tells Live Science, “We’re curious about what other strategies these guys are using.”

About Katherine J. Wu
Katherine J. Wu

Katherine J. Wu is a Boston-based science journalist and Story Collider senior producer whose work has appeared in National Geographic, Undark magazine, Popular Science and more. She holds a Ph.D. in Microbiology and Immunobiology from Harvard University, and was Smithsonian magazine's 2018 AAAS Mass Media Fellow.

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