瘙痒和挠痒有什么科学依据吗?

"Before, the focus was on next-generation antihistamines," Dr. Bautista said. "Now, it's on new molecular and cellular targets to develop new therapies. The pharmaceutical industry is recognizing that they have to go beyond antihistamines."
“以前，他们的研发重点一直是新一代的抗组胺药物，”鲍蒂斯塔博士说，“现在，他们则瞄准了新的分子和细胞靶标来开发新的疗法。医药行业已经认识到，他们不能再局限于抗组胺药物，必须有所超越。”

But pain pathways have to be dissected in minute detail if new targets are to be found. Many researchers say that one of the most important advances in the field was reported in the journal Nature in 2007 by a Washington University team led by Zhou-Feng Chen, who is now director of the itch center. Working with mice, his team was studying receptors, molecules on cells that respond to certain chemical signals to change the cells' behavior.
但是，要找到新的靶标，就必须将疼痛通路的每个微小的细节都剖析清楚。现任华盛顿大学瘙痒中心主任陈宙峰(Zhou-Feng Chen)领导团队利用小鼠研究了可对特定的化学信号作出反应，并改变细胞行为的细胞表面受体和分子。这一2007年发表在《自然》杂志(Nature)上的研究被众多研究人员一致认为是该领域最重要的进展之一。

The group was the first to find a receptor in the spinal cord that was specific for itching, called gastrin-releasing peptide receptor, or GRPR. The discovery helped to prove that signals for itching and pain travel on different pathways.
该小组首次在脊髓中发现了瘙痒特异性受体，称为胃泌素释放肽受体(gastrin-releasing peptide receptor)，简称GRPR。这一发现有助于证明瘙痒和疼痛的信号传导途径并不相同。

In an interview, Dr. Chen said that mice without the receptor — or with the receptor blocked by a drug — did not itch. Nor was the group without a receptor harmed by the lack of it.
陈博士在接受采访时表示，不具备该受体，或该受体被药物阻断的小鼠就不会产生瘙痒的感觉。且无受体组的小鼠并未因此而受到损害。

"If you block function of this receptor alone, you pretty much stop chronic itching," he said.
“仅仅阻断该受体的功能，就几乎足以给慢性瘙痒画上句号，”他说。

The receptor is present in humans, too, and Dr. Chen said it might be possible to develop a drug that would block it.
该受体也存在于人体之中，陈博士认为未来有望开发出一种可以阻断它的药物。

For many patients, new treatments cannot come soon enough.
但对于大多数患者而言，新疗法问世的速度还不够快。

Chronic itching becomes more common with age. One reason is that older people often develop dry skin, but Dr. Yosipovitch said the itching also might occur because certain nerves in the skin deteriorate — nerves that transmit pain and inhibit itching. "Then itch kind of pops out," he said.
随着年龄的增长，慢性瘙痒在人群中日渐常见。其原因之一是老年人往往存在皮肤干燥。但杨斯波维奇博士认为，皮肤中某些神经的受损也可能造成瘙痒——这些神经原本负责传导疼痛并抑制瘙痒，它们一出毛病，“瘙痒就蹦了出来，”他说。

Aging monkeys have provided some clues. When Dr. Yosipovitch was still at Wake Forest, he and his colleagues noticed older female macaques scratching their backs and lower limbs, the same spots where older people tend to itch.
衰老的猴子为此提供了一些线索。早在杨斯波维奇博士在维克森林大学工作时，他和同事们就发现老年雌性狝猴会抓挠自己的背部和下肢——老年人经常感到瘙痒的也是同样的部位。

They sent samples from the monkeys to Dr. Chen, who found extra activity in the skin and spinal cord from the gene that produces GRPR, the itch receptor. Why the gene becomes more active with aging is not known, but this finding in a primate supports the idea that the receptor is a good target for new drugs in people, Dr. Chen said.
他们将这些猴子的样本送到了陈博士的实验室。陈博士他们随后发现，在这些猴子的皮肤和脊髓里，表达瘙痒受体GRPR的基因过度活跃。陈博士表示，目前尚不清楚该基因为什么会随着衰老而趋于活跃，但这一在灵长类身上得到的发现支持这一观点：该受体是研发治疗人类瘙痒的新药的良好靶标。

Many older people have trouble with itching in hard-to-reach spots on the back, between or just below the shoulder blades.
许多老年人都存在这样的麻烦：瘙痒的部位正好位于后背上肩胛骨下方或其之间的位置，他们的手很难够着。

"It drives them crazy," said Dr. Cornelius, at Washington University. They rub against door jambs, stockpile back scratchers, and enlist others to scratch them.
“这简直要把他们逼疯了，”科尼利厄斯博士在华盛顿大学时说。他们只好用身体摩擦门框，大量购置痒痒挠，并要求其他人来帮他们瘙痒。

The condition has a name, notalgia paresthetica, and is often associated with spine and disk problems that pinch or damage nerves. The skin in the itchy spots may darken.
这种疾病名为感觉异常性背痛(notalgia paresthetica)，它通常与脊柱和椎间盘出现问题，压迫或损伤了神经相关。痒点处的肤色有可能会变暗。

"Some neurologists, I would say the majority, do not know about this," Dr. Yosipovitch said.
“一部分神经科医生，甚至可以说其中的大多数都不知道这一点，”杨斯波维奇博士说。

He and other doctors have prescribed various remedies — numbing patches, sometimes along with the hot-pepper ingredient capsaicin; Botox injections; pills like gabapentin that affect nerve transmission; and physical therapy to change posture. Often, it is possible to find something that helps.
他和其他医生也曾处方过多种治疗方法：止痒贴片，有时辅以辣椒中的成分辣椒素；注射肉毒杆菌毒素(Botox)；加巴喷丁(gabapentin)等可影响神经传导的药剂；物理治疗等，试图改善瘙痒症状。但基本上没有一种见效。

Dr. Yosipovitch said many patients found their way to him only after seeing multiple doctors who could not help and who sometimes misdiagnosed their problems as mental rather than physical.
杨斯波维奇博士说，许多患者都是在拜访过众多表示爱莫能助的医生（其中甚至有人将身体的瘙痒误诊为心理疾病）后才找上了自己。

"They're not crazy," he said.
“他们当然不是脑筋出了问题，”他说。

One of the patients was a boy who had scratched his arms and legs raw. Unable to find a cause or a treatment that worked, doctors had referred him and his family to a psychiatrist.
其中一名患者是个男孩子，他把自己的手臂和腿都抓挠得破了皮。医生找不到病因，也没什么有效的疗法，只好将他转诊给了心理医生。

In an interview, the patient, Joshua Riegel, now 18, said, "They said I was doing it to manipulate my parents." Thus began what he calls "that weird part of my life where they thought I was mentally ill."
这位名叫乔舒亚·里格尔(Joshua Riegel)的患者现年18岁，他在接受采访时说：“他们都说我这样是故意的，目的是为了作弄我的父母。”从那时候起，他称其为“我被当成精神病的一段最诡异的人生经历”开始了。

He was 12 or 13 when the psychiatrist prescribed antidepressants, which he dutifully took for two or three years. But they brought on terrible side effects: At one point he was hospitalized with suicidal thoughts.
在他十二三岁的时候，心理医生一直给他处方抗抑郁药物，他听话地坚持服用了两三年。可这些药物带来了可怕的副作用：他一度因为自杀念头而不得不住院。

As a last resort, his parents took him from their home in Hillsville, Va., to see Dr. Yosipovitch, who was then at Wake Forest.
抱着最后一丝希望，他的父母带他离开了位于弗吉尼亚州希尔斯维尔的家，来到维克森林大学拜访当时在那里工作的杨斯波维奇博士。

"He had a hunch on what it was," Mr. Riegel said.
“他好像凭直觉就知道是哪里不对劲，”里格尔先生说。

Tests found a rare form of a genetic disease, epidermolysis bullosa, that was causing a particularly destructive set of symptoms: intense itching and skin so fragile that scratching ripped it to shreds.
经过测试，研究人员发现他患有一种很罕见的遗传病——大疱性表皮松解症(epidermolysis bullosa)，这种病可以造成一系列极具破坏性的症状：剧烈瘙痒，皮肤极度脆弱，以至于连挠痒都会将皮肤划破。

"Dr. Yosipovitch was quite angry I was being told I was mentally ill when I wasn't," Mr. Riegel recalled.
“在得知明明没有精神病的我却被人说成是精神病时，杨斯波维奇博士非常生气，”里格尔先生回忆道。

Getting off the antidepressants lifted his spirits and let him be normal again. Since then, other drugs have been prescribed for the itching, with mixed results. It never really goes away, but Mr. Riegel uses video games or his cellphone to take his mind off it and keep from scratching.
停用抗抑郁药物后，他的精神重新振奋起来，并恢复了正常。此后，医生向他处方了其他药物来治疗瘙痒，效果好坏参半。虽然从未真正摆脱过瘙痒，但里格尔先生可以借助电脑游戏或手机转移自己的注意力，以避免抓伤自己。

For people with other types of chronic itching, Dr. Yosipovitch said: "This is just the beginning of a big era. In the next five years I predict there will be drugs targeted specifically for itch. We're in the middle of the tip of an iceberg."
对于患有其他类型慢性瘙痒的患者而言，杨斯波维奇博士说：“这个伟大的时代才刚刚拉开序幕。预计在接下来的五年里就会出现专门针对瘙痒的靶向药物。我们正站在冰山的一角上。”