Lawson S N, McCarthy P W, Prabhakar E
Department of Physiology, University of Bristol, United Kingdom.
J Comp Neurol. 1996 Feb 12;365(3):355-66. doi: 10.1002/(SICI)1096-9861(19960212)365:3<355::AID-CNE2>3.0.CO;2-3.
Intracellular voltage recordings and fluorescent dye injections were made in vitro in 107 neurons in lumbar dorsal root ganglia (DRGs) of 6- to 8-week-old rats. Calcitonin gene-related, peptide-like immunoreactivity (CGRP-LI) was examined in these neurones, which were divided into C-, A delta-, and A alpha/beta-fibre neurones on the basis of their conduction velocities (CVs). A-fibre neurones with CGRP-LI had significantly longer mean action potential (AP) and afterhyperpolarisation (AHP) durations than those without CGRP-LI. A delta neurones with CGRP-LI had significantly longer AHP durations, slower CVs and slower maximal fibre following frequencies than those without CGRP-LI. They also had longer AP durations (not significant). The largest A delta neurones were CGRP-LI negative, whereas the smaller cells were either positive or negative. A alpha/beta neurones with CGRP-LI also had longer mean APs (not significant) and AHPs (significant) than those without CGRP-LI, and the cell size distributions were similar for positive and negative neurones. Most A-fibre neurones with CGRP-LI had inflections on the falling phase of the somatic AP. Of the A-fibre neurones with such inflections (Ai neurones), those with CGRP-LI had longer AP durations (not significant) and longer AHP durations (significant) than Ai neurones without CGRP-LI, pointing to a functionally distinct subgroup of Ai neurones. There were no significant differences in electrophysiological properties or cell size measurements between C-fibre neurones with and without detectable CGRP-LI. The patterns of electrophysiological properties of A delta neuronal somata with CGRP-LI and of most, but not all, A alpha/beta neuronal somata with CGRP-LI are similar to those reported for cutaneous nociceptors with A fibres in rat (Ritter and Mendell [1992] J. Neurophysiol. 68:2033-2041). Because rat DRG neurones that express CGRP normally also express trkA (Averill et al. [1995] Eur. J. Neurosci. 7:1484-1494), the properties described here of neurones with CGRP-LI are probably the same as those of DRG neurones with trkA.
对6至8周龄大鼠腰段背根神经节（DRG）中的107个神经元进行了细胞内电压记录和荧光染料注射实验。检测了这些神经元中降钙素基因相关肽样免疫反应性（CGRP-LI），并根据其传导速度（CV）将它们分为C类、Aδ类和Aα/β类纤维神经元。具有CGRP-LI的A类纤维神经元的平均动作电位（AP）和超极化后电位（AHP）持续时间明显长于没有CGRP-LI的神经元。具有CGRP-LI的Aδ神经元的AHP持续时间明显更长，CV更慢，最大纤维跟随频率更慢，比没有CGRP-LI的神经元。它们的AP持续时间也更长（不显著）。最大的Aδ神经元CGRP-LI阴性，而较小的细胞则为阳性或阴性。具有CGRP-LI的Aα/β神经元的平均AP（不显著）和AHP（显著）也比没有CGRP-LI的神经元更长，阳性和阴性神经元的细胞大小分布相似。大多数具有CGRP-LI的A类纤维神经元在躯体AP的下降相有拐点。在有这种拐点的A类纤维神经元（Ai神经元）中，具有CGRP-LI的神经元的AP持续时间（不显著）和AHP持续时间（显著）比没有CGRP-LI的Ai神经元更长，这表明Ai神经元存在一个功能上不同的亚组。有或没有可检测到的CGRP-LI的C类纤维神经元在电生理特性或细胞大小测量方面没有显著差异。具有CGRP-LI的Aδ神经元胞体和大多数（但不是全部）具有CGRP-LI的Aα/β神经元胞体的电生理特性模式与大鼠中具有A纤维的皮肤伤害感受器所报道的相似（Ritter和Mendell [1992] J. Neurophysiol. 68:2033-2041）。因为正常表达CGRP的大鼠DRG神经元也表达trkA（Averill等人 [1995] Eur. J. Neurosci. 7:1484-1494），这里描述的具有CGRP-LI的神经元的特性可能与具有trkA的DRG神经元的特性相同。
