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A friend’s four year old daughter recently complained to me about how badly her mosquito bite itched. She was about to burst into tears. The fact that an uncomfortable itchy sensation can drive many of us to distraction led many scientists to believe that the nervous system deals with itch much as it does pain. Others spent years looking, unsuccessfully, for neurons that tell us to scratch rather than that we just hurt.
Now, according to a study in the August 7th issue of the journal Science, researchers say they’ve finally found specific itch neurons in mice. They located them in the mouse spinal cord by following up on previous research that showed that some mice respond to itchy stimuli more than others.
When scientists knocked out the itch neurons, the mice no longer had the urge to scratch in response to known itchy stimulus. But they could still sense and avoid pain, showing that itch and pain are processed independently.The researchers hope that these findings could eventually lead to better treatments for chronic itch, by targeting the specific biochemical pathways involved. As for the four-year-old? She forgot about her itchy bug bite as soon as lunch arrived.
—Cynthia Graber