Home | Skin, Hair and Nails | Scratching Beneath the Surface: the Cause of Chronic Itch

Scratching Beneath the Surface: the Cause of Chronic Itch

New Haven, Conn. — Millions of people suffer from relentless itching, unrelated to allergies or bug bites, that cannot be relieved by antihistamines or topical creams.

 

Now, a research team led by Yale School of Medicine has identified a peptide (a grouping of amino acids) produced in the body that may contribute to this kind of chronic itch. The discovery could open avenues for development of anti-itch treatments to relieve the discomfort. The study appears in the Journal of Neuroscience.

Building upon a previous study that showed how the peptide BAM8-22 evokes scratching in mice, the Yale-led team tested the effect on humans. BAM8-22 produced itching in each of 15 healthy volunteers, accompanied by sensations of pricking, stinging and burning. In comparison, another peptide that is identical to BAM8-22, except for the deletion of the last four amino acids, produced little or no sensation. Further, researchers discovered that pretreatment of the tested skin with an antihistamine cream did not inhibit the sensations evoked by BAM8-22.

The leader of the research team, Robert LaMotte, professor of anesthesiology and neurobiology at Yale School of Medicine, explained the implications for potential treatment: "BAM8-22 binds to a receptor that is found in sensory nerve fibers supplying the skin of the mouse and a receptor that has structural similarities in human skin. Development of an antagonist of this receptor may prove useful in the treatment of itch that is not relieved by antihistamines."

"Histamine is a chemical substance released by mast cells in the skin. It is a major contributor to itch from insect bites and hives caused by certain foods, drugs, infection or emotional stress; this type of itch responds well to antihistamines," LaMotte said. "But for chronic itch from most disorders of the skin, such as atopic dermatitis, or itch accompanying certain neurological diseases, like multiple sclerosis or systemic diseases — including those of the liver or kidney — antihistamines are not effective."

Other authors of the study are Parul Sikand, associate research scientist at Yale School of Medicine, and Xinzhong Dong, associate professor at Johns Hopkins School of Medicine and co-leader of the research team.

The study was funded by grants from the National Institutes of Neurological Disorders and Stroke.

 PRESS CONTACT: Helen Dodson 203-436-3984

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