Responsiveness of C Neurons in Rat Dorsal Root Ganglion to 5-Hydroxytryptamine-Induced Pruritic Stimuli In Vivo
Responsiveness of C Neurons in Rat Dorsal Root Ganglion to 5-Hydroxytryptamine-Induced Pruritic Stimuli In Vivo
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DOI：
10.1152/jn.00938.2009
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发表时间：
2010-07-01
影响因子：
2.5
通讯作者：
Yoshimura, Megumu
中科院分区：
文献类型：
--
作者：
Hachisuka, Junichi;Furue, Hidemasa;Yoshimura, Megumu
张文忠，张文忠，张文忠.大鼠背根神经节C神经元对5-羟色胺诱发的在体炎症刺激的反应性。J Neurophysiol 104：271-279，2010.首次发表于2010年5月19日; doi：10.1152/jn.00938.2009。瘙痒是皮肤病中的常见症状，并且引起皮肤的无休止的抓挠，这加重了病情。然而，瘙痒感的机制是神秘的。本研究通过行为学测试和在体大鼠背根神经节（DRG）神经元电生理记录，分析了5-羟色胺（5-HT）局部皮肤给药引起的过敏性刺激的反应。局部应用5-羟色胺的喙回引起抓挠，而应用的车辆没有。皮下注射阿片受体拮抗剂纳洛酮后，抓挠次数减少，表明抓挠优先由瘙痒而不是疼痛感介导。为了阐明DRG神经元对局部应用的5-HT的反应的放电特性，从DRG神经元在体内进行细胞内记录。A β和A δ神经元对5-HT无反应，而C神经元对5-HT有重复放电反应，其中25个（27%）可分为两种类型：一种是短暂型，放电频率较低，在5 min内逐渐降低;另一种是持久型，具有高放电频率，5 min后持续增加。持久型C神经元放电模式的时间过程与抓挠行为相似。有趣的是，长持续型神经元的快后超极化明显小于5-HT不敏感型神经元。这些结果表明，大鼠DRG内对5-HT敏感的长持续放电C神经元负责向脊髓传递炎症信息。
Hachisuka J, Furue H, Furue M, Yoshimura M. Responsiveness of C neurons in rat dorsal root ganglion to 5-hydroxytryptamine-induced pruritic stimuli in vivo. J Neurophysiol 104: 271-279, 2010. First published May 19, 2010; doi:10.1152/jn.00938.2009. Itching is a common symptom in dermatologic diseases and causes restless scratching of the skin, which aggravates the condition. The mechanism of the itch sensation, however, is enigmatic. The present study included behavioral tests and electrophysiological recordings from rat dorsal root ganglion (DRG) neurons in vivo to analyze the response to pruritic stimuli induced by topical application of 5-hydroxytryptamine (5-HT) to the skin. Topically applied 5-HT to the rostral back evoked scratching, whereas application of the vehicle did not. Following subcutaneous injection of the opioid receptor antagonist naloxone, the number of scratches decreased, suggesting that the scratching was preferentially mediated by itch but not pain sensation. To elucidate the firing properties of DRG neurons in response to topically applied 5-HT, intracellular recordings were made from DRG neurons in vivo. None of the A beta and A delta neurons responded to 5-HT; in contrast, 25 of 91 C neurons (27%) exhibited repetitive firing in response to 5-HT, which could be classified into two firing patterns: one was a transient type, characterized by low firing frequency that decreased within 5 min; the other was a long-lasting type, having high firing frequency that continued increasing after 5 min. The time course of the firing pattern of long-lasting C neurons was comparable to the scratching behavior. Intriguingly, the long-lasting-type neurons had a significantly smaller fast afterhyperpolarization than that of the 5-HTinsensitive neurons. These observations suggest that the long-lastingfiring C neurons in rat DRG sensitive to 5-HT are responsible for conveying pruritic information to the spinal cord.