THE TIME COURSE AND SPECIFICITY OF THE CHANGES IN THE BEHAVIORAL AND DORSAL HORN CELL RESPONSES TO NOXIOUS STIMULI FOLLOWING PERIPHERAL-NERVE CAPSAICIN TREATMENT IN THE RAT
THE TIME COURSE AND SPECIFICITY OF THE CHANGES IN THE BEHAVIORAL AND DORSAL HORN CELL RESPONSES TO NOXIOUS STIMULI FOLLOWING PERIPHERAL-NERVE CAPSAICIN TREATMENT IN THE RAT
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DOI：
10.1016/0306-4522(82)90119-1
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发表时间：
1982-01-01
期刊：
影响因子：
3.3
通讯作者：
WOOLF, CJ
中科院分区：
文献类型：
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作者：
FITZGERALD, M;WOOLF, CJ
辣椒素是一种特异性作用于感觉初级传入纤维的神经毒素，我们在一组大鼠的1条坐骨神经上局部施用辣椒素。从这之后的1-16天，进行了一系列的行为和电生理研究。大鼠足部对受控热有害刺激的退出潜伏期显著提高（200%）。在治疗后第1天达到高峰；然后，反应下降到稳定但较高的水平。16天。对有害机械刺激的反应不受辣椒素处理的影响。脊髓背角的单单元分析显示，在治疗后的前2天，响应C外周射射的深层（4、5和6）神经元数量正常（60%）。在处理后第3天，输入C的细胞数量开始下降，在第7天达到最大降幅（25%），并一直持续到第16天。与c诱发反应的延迟效应相反，对皮肤有害加热作出反应的细胞数量在第1天从控制水平的60%下降到20%，并保持下降长达16天。因此，局部辣椒素治疗后热镇痛的发生与背角中有害热诱发反应减少的时间过程密切相关。由于在早期预处理时，电c诱发的活动是正常的，这些影响可能是由于对皮肤中外周c纤维伤害感受器的作用。在后期，辣椒素似乎也作用于纤维的中央末端，减少向二级背角神经元的传递。
Capsaicin, a neurotoxin which acts specifically on sensory primary afferent C[chemosensitive]-fibers was applied locally to 1 sciatic nerve of a group of rats. From 1-16 days following this a series of behavioral and electrophysiological studies were performed. The latency of foot withdrawal of the rats to a controlled thermal noxious stimuli was significantly elevated (200%). The peak increase occurred on day 1 after treatment; the responses then fell to a steady but elevated level for .ltoreq. 16 days. Responses to noxious mechanical stimuli were unaffected by capsaicin treatment. Single unit analysis of the dorsal horn of the spinal cord showed that the number of neurons in deep laminae (4, 5 and 6) responding to a C peripheral volley was normal (60%) for the 1st 2 days after treatment. On day 3 posttreatment, the number of cells with a C input began to fall reaching a maximal decrease on day 7 (25%), where it remained up to day 16. In contrast to this delayed effect on C-evoked responses, the number of cells responding to noxious heating of the skin fell from control levels of 60% down to 20% on day 1 and remained decreased for up to 16 days. The onset of thermal analgesia following local capsaicin treatment therefore, closely parallels the time course of the decrease of noxious heat-evoked responses in the dorsal horn. Since at early pretreatment times, the electrically C-evoked activity is normal these effects are likely to be due to action on peripheral C-fiber nociceptors in the skin. At a later stage capsaicin also appears to act on the central terminals of fibers reducing transmission to 2nd order dorsal horn neurons.