Naked Mole-Rats Offer Pain Relief Insights

on September 25 2012 5:03 PM
naked mole-rat
Proteins have a lot to do with naked mole rats' unusual longevity. Wikimedia Commons/Roman Klementschitz

It might look like a wrinkly hot dog with teeth, but the naked mole-rat is actually an amazingly hardy animal. They can live up to be 30 years old – more than 10 times the lifespan of some similarly-sized rodents. As far as we know, they’re impervious to cancer. And they live in environments that most mammals would find toxic.

Maybe, by finding out what makes the naked mole-rat so long-lived and robust, we can borrow a little bit of that staying power for ourselves. Aging researchers, for example, recently zeroed in on the brain protein Neuregulin 1, or NRG-1, finding that naked mole rats had the most plentiful and persistent supply of it among all the rodent species they studied.

Now some researchers are trying to figure out how naked mole-rats can cheerfully traipse through acidic fumes that make other animals gag. The answer could lead to better treatments for chronic pain.

In a recent paper published in the journal PLoS ONE, researchers from the University of Illinois at Chicago delved into how naked mole-rats are able to survive in carbon dioxide-rich environments that would be too acidic and painful for us to survive in. They say understanding the rodent’s mechanism of resisting pain could contribute to more powerful treatments for chronic pain in humans.

Carbon dioxide builds up in naked mole-rat nests because their underground habitats are very crowded and poorly ventilated, the authors wrote. These conditions make the air in a naked mole-rat nest very acidic, which would normally trigger pain pathways that are activated by acidic fumes.

The UIC researchers wanted to test the naked mole-rat’s behavior in acidic environments, so they put test animals in cages that contained various strengths of acidic fumes. The naked mole-rats seemed oblivious to most concentrations of fumes, wandering around in acidic and non-acidic environments for about the same amount of time. They only began to avoid acidic fumes at very high levels, way beyond what made experimental rats and mice flee the room, according to the paper.

To gauge whether or not the naked mole-rats were responding physiologically to the acidic environment, the scientists measured a protein called c-Fos, which can help determine if nerve cells are firing.

They found that the naked mole-rats had no activity in the trigeminal nucleus – a bundle of nerves in the brainstem that serves as a repository for sensory information, including pain -- in response to the acidic fumes. But in rats and mice, acidic environments activated the trigeminal nucleus, and caused the animals to rub their noses and try to avoid the fumes.

The authors think that the naked mole-rat's unique pain pathway is a special adaptation for living in its crowded, carbon-dioxide rich environment. By better understanding how naked mole-rats tamp down their pain response to acidic environments, scientists may be able to dull the pain caused by acidification of injured tissues.

"Acidification is an unavoidable side-effect of injury," author Thomas Park said in a statement. "Studying an animal that feels no pain from an acidified environment should lead to new ways of alleviating pain in humans."

SOURCE: LaVinka et al. “Blunted Behavioral and C Fos Responses to Acidic Fumes in the African Naked Mole-Rat.” PLoS ONE 7: e45060.

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