Regardless of the remarkable advances we seem to make on an almost hourly basis these days, as human beings with the capacity for everything from capturing images on film/microchips to rocketing to Mars, there is still so much we hardly understand. Even some of the most basic elements of our world can still elude our intellectual grasp.
There are still so many itches we just can't seem to scratch.
But one of these elementary components to our world — why we itch — has now received advanced study and it's one more thing we as a society may finally understand a bit better than before, as per a report in Scientific American published on Tuesday, April 23.
In the past, scientists believed that we itch because of a "mild manifestation" of pain or "malfunction" of nerve endings that are super-sensitive and find themselves in a "feedback loop." A new development, however, shows this is not the case, as scientists have now zeroed in on those singular nerve cells that make us itch.
Along with their colleagues, neuroscientists Liang Han and Xinzhong Dong of Johns Hopkins University came upon a unique protein receptor called MrgprA3 that exists on certain sensory neurons with nerve endings in the skin. These researchers found that such neurons produced electric signals when affected by chemicals that cause itching, whereas they did not react similarly under conditions involving "painful" stimuli such as hot water.
A recent study published by the itch researchers in Nature Neuroscience illustrates that when genetic engineering was used to selectively kill off all of the MrgprA3 neurons in mice, those mice stopped scratching themselves entirely, even after being exposed to itch-inducing substances.
"Our current study has shown experimentally for the first time the existence of itch-specific nerves," Dong said.
That itch has now been determined to be separate from those senses that affect pain, temperature and touch means new drugs can be developed that block MrgprA3 receptors. This is good news for anyone who has ever been afflicted by things such as poison ivy or eczema.
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