Scientists Turn Off Ability to Feel Cold

Scientists Turn Off Ability to Feel Cold

file000647336049Scientists have discovered a way to shut down the body’s ability to feel cold. It’s a breakthrough they say might one day lead to the development of more effective ways to treat pain.

“The problem with pain drugs now is that they typically just reduce inflammation, which is just one potential cause of pain, or they knock out all sensation, which often is not desirable,” said David McKemy, associate professor of neurobiology at the University of Southern California’s Dornsife College of Letters, Arts and Sciences.

“One of our goals is to pave the way for medications that address the pain directly in a way that does not leave patients completely numb.”

McKemy and his research team managed to selectively shut off the ability of mice to sense cold by manipulating a sensory network of neurons in their skin. They did it by usinga bacterial toxin to kill neurons equipped with so-called TRPM8 channels, cellular structures that help relay sensations of cold. However, neurons that sense heat, touch and mechanical pain were left intact.

With the help of a mouse-tracking software program developed by one of McKemy’s students, the researchers tested with and without TRPM8 neurons on a multi-temperature surface. The surface temperature ranged from 32 to 122 degrees, and mice were allowed to move freely among the regions.

The control mice tended to stick to an area around 86 degrees and avoided both colder and hotter areas.

Mice without TRPM8 neurons avoided the hotter surfaces and but not the cold — even when the cold should have been painful or was potentially dangerous.

In tests of grip strength, both the control and those without the TRPM8 neurons had the same responses to touch and coordinated movement, such as balancing on a rod while it rotated.

McKemy told Health Day, further research could help patients who may have extreme sensitivity to cold as a side effect to their medication.

“Some side effects of certain chemotherapy drugs cause sensitivity to the cold, so much that a cool glass of water is excruciatingly cold. Some diabetics and people who have bone injuries also show these sorts of things,” McKemy said.

But the ability to turn off cold has more implications than just getting rid of momentary discomfort. By narrowing in on pain at the molecular level, doctors hope to gain a better understanding of the specific ways in which people feel sensations.

And that, said McKemy, might one day lead to the treatment of pain with more precision, along with development of medications that don’t knock out all ability to feel for suffering patients.

 

Authored by: Richard Lenti