Mechanical response properties of A and C primary afferent neurons innervating the rat intracranial dura
Mechanical response properties of A and C primary afferent neurons innervating the rat intracranial dura
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DOI：
10.1152/jn.00029.2002
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发表时间：
2002-12-01
影响因子：
2.5
通讯作者：
Strassman, AM
中科院分区：
文献类型：
--
作者：
Levy, D;Strassman, AM
颅内硬脑膜接受来自三叉神经节的小纤维感觉神经支配，该神经被认为与包括偏头痛在内的某些类型的头痛有关。研究了硬脑膜传入神经元的机械响应特性，以研究不同人群在阈值、斜率、适应性和机械敏感性发生率方面的差异。在尿素麻醉大鼠的三叉神经节中记录硬脑膜传入神经元，并通过它们对硬脑膜休克的持续潜伏期反应来识别它们。根据对硬脑膜休克的反应潜伏期，将神经元分为快速A （>5 m/s）、慢速A（5大于等于传导速度（CV）大于等于1.5 m/s）和C （< 1.5 m/s）。机械感受野是通过抚摸或压痕硬脑膜的外表面来识别的。用伺服力控制的机械刺激器对硬脑膜感受野进行2秒等速等速压痕刺激，得到刺激-反应曲线。慢A种群具有最高的机械敏感单位比例（97%）、最高的坡度和最低的阈值。因此，通过所有三个标准，慢a具有最高的机械敏感性。相反，快速A种群的机械敏感性最低，因为它的机械敏感性单位百分比最低（66%），斜率最低，阈值最高。新C居群在这三个性质上都是中间的，但与慢a比与快a更相似。三种纤维的斜率与阈值呈负相关。大多数神经元对持续2秒的刺激表现出缓慢的适应反应。根据拟合的指数曲线是衰减到零还是衰减到非零平台，对自适应神经元进行细分；后一组含有最敏感的神经元，因为它们具有最低的阈值和最高的斜率。非适应神经元的初始放电速率通常低于适应神经元。快速的A神经元比慢速的A和C神经元表现出更大、更快的适应能力。无论CV大小，坡度最小的神经元的适应速度相对较快。传导较慢的部分C神经元与其他C神经元有许多特性：更多的机械不敏感神经元，更高的阈值，更多的非适应神经元。这些机械反应特性的差异可能部分与背根神经节细胞亚群中涉及脉冲产生的膜电流的差异有关。
The intracranial dura receives a small-fiber sensory innervation from the trigeminal ganglion that is thought to be involved in some types of headaches, including migraine. Mechanical response properties of dural afferent neurons were examined to investigate variation across the population in the properties of threshold, slope, adaptation, and incidence of mechanosensitivity. Dural afferent neurons were recorded in the trigeminal ganglion of urethan-anesthetized rats and were identified by their constant-latency response to dural shock. Neurons were classified as fast A (>5 m/s), slow A (5 greater than or equal to conduction velocity (CV) greater than or equal to 1.5 m/s), or C (< 1.5 m/s), based on response latency to dural shock. Mechanical receptive fields were identified by stroking or indenting the outer surface of the dura. Stimulus-response curves were obtained from responses to 2-s constant-force indenting stimuli of graded intensities delivered to the dural receptive field With a servo force-controlled mechanical stimulator. The slow A population had the highest percentage of mechanosensitive units (97%) as well as the highest slopes and the lowest thresholds. Thus by all three criteria, the slow As had the highest mechanosensitivity. Conversely, the fast A population had the lowest mechanosensitivity in that it had the lowest percentage of mechanosensitive units (66%), the lowest slopes, and the highest thresholds. ne C population was intermediate with respect to all three properties but was much more similar to the slow As than to the fast As. All three fiber classes showed a negative correlation between slope and threshold. The majority of neurons showed a slowly adapting response to a maintained 2-s stimulus. Adapting neurons could be subdivided based on whether the fitted exponential curve decayed to zero or to a nonzero plateau; the latter group contained the most sensitive neurons in that they had the lowest thresholds and highest slopes. Nonadapting neurons generally had lower initial firing rates than adapting neurons. Fast A neurons exhibited greater and more rapid adaptation than slow A and C neurons. Neurons with the lowest slopes, regardless of CV, had relatively rapid adaptation. The more slowly conducting portion of the C population was distinguished from the other C neurons by A number of properties: more mechanically insensitive neurons, higher thresholds, and more nonadapting neurons. These differences in mechanical response properties may be related in part to differences in membrane currents involved in impulse generation that have been described in subpopulations of dorsal root ganglion cells.