THURSDAY, May 23 (HealthDay News) -- The sensation of itching is hardwired into the nervous system and can be traced back to a small molecule released in the spinal cord, according to a new study in mice.
Researchers say this molecule, known as natriuretic polypeptide b (Nppb), triggers a signal that passes through the central nervous system. Ultimately, this signal is experienced as an itch. Since the nervous systems of humans and mice are similar, the researchers concluded that a similar process probably occurs in people.
"Our work shows that itch, once thought to be a low-level form of pain, is a distinct sensation that is uniquely hardwired into the nervous system with the biochemical equivalent of its own dedicated landline to the brain," study senior author Mark Hoon, a scientist at the U.S. National Institute of Dental and Craniofacial Research, said in an institute news release.
The findings might someday help scientists develop treatments for chronic itch conditions, such eczema and psoriasis, the researchers suggested.
For the new study, the researchers first identified the signaling components on nerve cells that contain a molecule called TRPV1. These nerve cells help to monitor certain external conditions, such as extreme temperature changes or detecting pain. In examining how these cells recognize various sensations, the study authors screened the molecule, Nppb.
"We tested Nppb for its possible role in various sensations without success," study lead author Santosh Mishra, a researcher in the Hoon laboratory, said in the news release. However, he added, "When we exposed the Nppb-deficient mice to several itch-inducing substances, it was amazing to watch. Nothing happened. The mice wouldn't scratch."
When Nppb or its nerve cell was not present, mice stopped scratching because the signal wasn't going through, the researchers explained.
The investigators also focused on the dorsal horn
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