發表在《科學》（Science）雜志上的一項研究表明，老鼠具有特殊的與癢有關而不是與疼痛有關的神經細胞。

    Scratching Surface of Itch

    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.

    破解發癢的秘密

    最近我的一個朋友的四歲大的女兒向我抱怨，她被蚊子叮咬后非常難受，以致于都快要哭出來了。鑒于瘙癢引起的不適能讓我們中的大多數人心煩意亂，因此科學家 們相信神經系統在處理瘙癢的時候像處理疼痛一樣。有些科學家們花了多年的時間想找到那些告訴我們撓癢的神經細胞而不是那些告訴我們疼痛的神經細胞，但是他 們沒有獲得成功。

    目前，根據發表在8月7日《科學》（Science）雜志上的一項研究，研究者們說他們終于在老鼠身上找到了特定的瘙癢神經細胞。以前的研究顯示，相比于其它老鼠，有些老鼠對瘙癢刺激反應更甚，研究者們深入了這些研究，進而在老鼠的脊髓中找到了這些神經細胞。

    當科學家們把這些神經細胞從老鼠身上取走后，這些老鼠對已知的瘙癢刺激不再做出撓癢反應。但是，它們仍然能感受并避免疼痛，這表明老鼠的神經系統是分別處 理癢和疼痛的。研究者們希望，通過針對性地處理瘙癢過程中的特定生物化學途徑，這些研究最終能幫助更好地治療慢性瘙癢。對上面提到的那個四歲小女孩有何作 用呢？一到午餐時間到來，她就忘記蚊蟲曾叮咬過她了。