Response properties of dorsal root reflexes in cutaneous C fibers before and after intradermal capsaicin injection in rats.
Response properties of dorsal root reflexes in cutaneous C fibers before and after intradermal capsaicin injection in rats.
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大鼠皮内注射辣椒素前后皮肤 C 纤维背根反射的反应特性。
DOI：
10.1016/j.neuroscience.2005.01.039
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Dougherty,PM
中科院分区：
文献类型：
--
作者：
Weng,H-R;Dougherty,PM
C纤维背根反射（DRR）有助于神经源性炎症，也可能是由皮内辣椒素诱导的触摸诱发疼痛（异常性疼痛）。本文观察了39只成年雄性大鼠皮内注射辣椒素前后腓肠神经C纤维对分级机械刺激的反应。111根纤维中有三分之二没有自发活动，而其余的纤维平均每秒1.41±0.25个自发逆行峰。在静止的C纤维只有两个兴奋性感受野，而活跃的C纤维表现出三种模式的活动，兴奋性反应，抑制性反应，或没有反应的机械刺激。兴奋性反应是单独的高强度机械刺激，而抑制性反应是由有害和无害的机械刺激以分级的方式诱发的。皮内注射辣椒素增加自发和诱发DRR在所有C纤维的兴奋性反应的机械刺激，但没有获得的反应无害的刺激。辣椒素最初在具有抑制性或无感受野的C纤维中产生对自发活动的抑制，但后来恢复并达到高于基线的速率。恢复自发放电后再次施加机械刺激未能产生任何反应。局部应用1 mM β-丙氨酸（GABA转运蛋白的竞争性拮抗剂）可增加自发DRR，并通过同侧脊神经L5损伤消除，验证了逆行起源。C纤维DRR在正常感觉传递和痛觉过敏过程中的作用进行了讨论。
C fiber dorsal root reflexes (DRR) contribute to neurogenic inflammation and possibly also to touch-evoked pain (allodynia) induced by intradermal capsaicin. The responses of C fibers in the sural nerve to graded mechanical stimuli before and following intradermal capsaicin were studied in 39 adult male rats. Two-thirds of 111 fibers were without spontaneous activity, while the remaining fibers averaged 1.41±0.25 spontaneous antidromic spikes per second. Among the quiescent C fibers only two had excitatory receptive fields, whereas the active C fibers showed three patterns of activity, an excitatory response, an inhibitory response, or no response to mechanical stimulation. The excitatory responses were to high intensity mechanical stimuli alone, while inhibitory responses were evoked in a graded fashion by both noxious and innocuous mechanical stimuli. Intradermal injection of capsaicin increased spontaneous and evoked DRRs in all C fibers with excitatory responses to mechanical stimuli, but none acquired responses to innocuous stimuli. Capsaicin initially produced inhibition of spontaneous activity in C fibers with inhibitory or no receptive fields, but this later resumed and achieved a rate higher than baseline. Mechanical stimuli re-applied following the resumption of spontaneous discharges failed to produce any response. Spontaneous DRRs were increased by topical application of 1 mM β-alanine (a competitive antagonist for GABA transporters) and abolished by ipsilateral spinal nerve L5 lesion, verifying antidromic origin. The role of C fiber DRRs in normal sensory transmission and during hyperalgesia is discussed.