Itch Gene Discovered

Relief may soon be at hand for chronic scratchers:-
Scratch no more. A remedy for that unpleasant itching sensation could be in the offing with researchers spotting the first ever gene responsible for itchiness in the central nervous system.

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Itching is a widespread problem often associated with skin diseases.

The discovery of the itch gene  GRPR (gastrin-releasing peptide receptor) — by two Washington University School of Medicine researchers could lead to treatments that provide relief from chronic and severe scratchiness.

Zhou-Feng Chen and his post-doctoral fellow Yan-Gang Sun reported in Nature last week the GRPR gene codes for a receptor that resides in a very small population of spinal cord nerve cells that relay pain and itch signals. Their tests on mice showed that the animals that lacked this gene scratched much less than those having it when given itchy stimuli.

Chronic itching is a widespread problem and is often associated with skin disorders such as eczema. But sometimes kidney failures or liver disorders too trigger an itching sensation. It can also be a serious side effect of certain cancer therapies or powerful painkillers like morphine. For some, chronic itching can be very disruptive, interfering with sleep or resulting in scarring. Whatever the cause, effective treatment options are limited for itchiness.

Traditionally, scientists regarded itchiness as just a less intense version of the pain sensation. As a result, research on itching has been patchy. Itch research has always lived in the shadow of pain research,….says Chen.

In the beginning, Chen’s team, too, wasn’t actually looking for the itch gene. The scientists stumbled upon it accidentally while trying to figure out the genes associated with the pain stimuli. Among the pain-sensing genes they identified, GRPR stood out because it was present in only a few nerve cells in the spinal cord known to relay pain and/or itch signals to the brain. This prompted them to study some mice that were missing the GRPR gene to find out how they were different from normal mice.

The research was a little disappointing at first,  says Chen.  The knockout mice seemed to have the same reactions to painful stimuli as normal mice.

But the puzzle was resolved when his co-worker, Sun, injected a substance that stimulated GRPR to the spinal cords of normal mice — the rodents started scratching themselves as if they had a severe itch. This tip off led to detailed investigation that resulted in the discovery of the first gene implicated in the urge to itch.

Source:The Telegraph (Kolkata, India)

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