Scientists pinpoint cells that send itch message to brain

The AP (8/7, Neergaard) reports that, according to research published online Aug. 6 in the journal Science, “scientists have pinpointed a key group of cells that sends itch-alerts to the brain. When researchers at Washington University in St. Louis knocked out those cells in mice, it alleviated their itchiness without affecting their ability to sense pain — work that opens a possible new target for creating better itch relievers.”

BBC News (8/6) explained that the investigators “found itch and pain signals seem to be transmitted along different pathways in the spinal cord.” Two years ago, the Washington University team “identified an ‘itch gene,’ called GRPR.” For the present study, “they injected the spinal cord of mice with a toxin that killed off cells in which the gene was active,” and by so doing “were able to eliminate the scratch response in some animals completely.” Because the animals “continued to respond normally to pain,” that demonstrated that “the key cells were active in transmitting the sensation of itching, but not the sensation of pain.”

Pointing out the clinical implications of the finding, the UK’s Daily Mail (8/7) reports, “As well as eczema sufferers, likely beneficiaries of new treatments include diabetics and liver patients, who are often plagued by the urge to scratch.” In addition, “kidney dialysis patients often suffer severe itching as a consequence of their kidney failure. Those affected are 17 percent more likely to die than other dialysis patients, possibly due to loss of sleep.” Patients with AIDS also experience “chronic itching,” while “some cancer patients find their painkillers irritate their skin to such an extent that they have to cut back on the drugs.” In all these cases, “scratching can cause severe skin damage, leading to infections in patients who are already very ill,” as well as discomfort and distress.

The Dayton Business Journal (8/6) and Reuters (8/7) also covered the story, as did Time (8/6, Blue) in its Wellness blog.

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