© ampyang/ShutterstockScientists have discovered specific nerves responsible for sensing itch. The new discovery could lead to better anti-itch treatments
A mysterious source of itchiness has been found. Certain nerve cells are specialized to detect itchy sensations, and those receptors don't detect painful sensations, according to a new study.
The finding, published Dec. 23 in the journal
Nature Neuroscience, helps resolve a long-standing debate over whether itchiness is just a weird form of pain. Additionally, now that they have pinpointed the responsible nerve fibers, researchers could silence those nerves to develop better anti-itch treatments, said Ethan Lerner, a neuroscientist at Harvard University who was not involved in the study.
"This is a very convincing piece of work," Lerner told LiveScience. Scientists "can perhaps target this particular type of nerve as a means of treating itch, but still allow you to experience the protective aspect of pain."
Itchy mysteryFor decades,
why we itch has been a mystery. While some pain nerves have been found to fire in response to itchy stimulants, nerves that responded solely to itch proved elusive. Some researchers even wondered whether itch and pain were always processed by the same nerve fibers, but interpreted by the brain differently, said study co-author Xinzhong Dong, a neuroscientist at Johns Hopkins University.
But the the urge to scratch seemed different in key ways from the experience of pain. For instance, when a mosquito bites, most people feel a powerful desire to scratch the bite, while the pain of touching a hot stove causes people to recoil, Dong told LiveScience.
Itch nervesTo identify cells that
sense itch, Dong and his colleagues genetically engineered mice whose nerve cells glowed fluorescent green when firing. The researchers then exposed the mice to irritating compounds, such as histamine and the active ingredient in itching powder, and looked for nerves that fired (and glowed green) as a result.
When the researchers burned out the nerves that lit up, the mice scratched a lot less, suggesting they were less itchy.
But that wasn't enough to prove that the nerves only sense itch, because in theory those neurons could also
sense pain. Therefore, the researchers specifically activated just those itch-detecting nerves in the faces of the mice. The animals then scratched their faces with their back paws, which they only do when itchy. (When they are in pain, they wipe their faces with their front legs.)
The newly discovered itch nerves sit inside the spine, near the spinal cord, and only innervate locations within the skin. That explains why people feel the urge to scratch their skin, but don't feel itchy in internal organs, Dong said.
"You can't have an itchy pancreas," he said.
Scratch that itchThe new findings are important because they provide a target for anti-itch medications. Current options, like anti-histamines or steroids, usually work by reducing inflammation, while many only eliminate the cause of itch for a narrow subset of problems, such as hives, Lerner said.
"Steroids are sort of a shotgun, and antihistamines, almost all the time, are hitting the wrong target," he said.
While the newly discovered nerves can't explain all itchiness (there are probably other nerves which sense both
itch and pain), targeting these nerves could be a huge improvement over current treatments, Lerner said.
After a while I just read these kinds of stories when I have insomnia because they help put me to sleep they are so boring. The subtext here is that Morgellons got out of control. It was supposed to be a re-wiring of the human circuitry BELOW THE THRESHOLD OF PERCEPTION and without all of the wiry bits coming out of people's skin. So a nice 'convincing' piece like this provides the cover for them studying the ability to turn off the itch response so that when EVERYONE finds out they have been infected with Morgellons but it is only a small percentage of the population that had an immune system reaction to it, they can turn off the itch, let the re-wiring continue because the masses will fall back to sleep as long as they are confident that the Borg Queen can rewire them without it cutting into their Short Game.
And what is convincing about a 'science' story when most of the journal articles are basically made up on the fly by the submitters? How can glowinthedark nerves be any kind of indicator of normalcy when the Heisenberg Uncertainty principle says that just doing an experiment changes the outcome?
Like I said: nitey nite.