Separate peripheral pathways for pruritus in man
Separate peripheral pathways for pruritus in man
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DOI：
10.1152/jn.90482.2008
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发表时间：
2008-10-01
影响因子：
2.5
通讯作者：
Ringkamp, Matthias
中科院分区：
文献类型：
--
作者：
Namer, Barbara;Carr, Richard;Ringkamp, Matthias
最近的研究结果表明，人类皮内插入牛皮针产生的瘙痒是不依赖组胺的。非组胺能瘙痒的神经机制知之甚少。为探讨哪些神经纤维介导了男性皮肤瘙痒，用显微神经学技术记录了健康志愿者腓神经皮肤C-纤维的动作电位。机械反应和不敏感的C-伤害性感受器对牛皮针、组胺和辣椒素的反应性进行了测试。所有受试机械反应C单位(24/24，但无机械不敏感C纤维(0/17))均能引起瘙痒并激活。组胺也会引起瘙痒，但与母牛不同，它只在机械不敏感的单位引起持久激活(8/12)。在机械反应的C单位中，组胺不引起或仅引起与瘙痒的时间进程无关的短暂和微弱的反应。注射辣椒素激活了六个机械反应纤维中的四个和四个机械不敏感C纤维中的三个。母牛和组胺激活明显不同的非重叠的C纤维群体，同时引起相似的瘙痒感觉。我们假设，母鸡激活了一条瘙痒通路，该通路起源于外周的表面机械反应(多模式)C纤维，或许还有其他传入单位。它不同于组胺介导的瘙痒通路，也不涉及组胺敏感的机械不敏感纤维。
Recent findings suggest that itch produced by intradermal insertion of cowhage spicules in human is histamine independent. Neuronal mechanisms underlying nonhistaminergic itch are poorly understood. To investigate which nerve fibers mediate cowhage induced itch in man, action potentials were recorded from cutaneous C-fibers of the peroneal nerve in healthy volunteers using microneurography. Mechano-responsive and -insensitive C-nociceptors were tested for their responsiveness to cowhage spicules, histamine, and capsaicin. Cowhage spicules induced itching and activated all tested mechano-responsive C-units (24/24, but no mechano-insensitive C-fibers (0/17). Histamine also induced itch, but in contrast to cowhage, it caused lasting activation only in mechano-insensitive units (8/12). In mechano-responsive C-units, histamine caused no or only short and weak responses unrelated to the time course of itching. Capsaicin injections activated four of six mechano-responsive fibers and three of four mechano-insensitive C-fibers. Cowhage and histamine activate distinctly different nonoverlapping populations of C-fibers while inducing similar sensations of itch. We hypothesize that cowhage activates a pathway for itch that originates peripherally from superficial mechano-responsive (polymodal) C-fibers and perhaps other afferent units. It is distinct from the pathway for histamine-mediated pruritus and does not involve the histamine-sensitive mechano-insensitive fibers.