Electrophysiological differences between nociceptive and non-nociceptive dorsal root ganglion neurones in the rat in vivo
Electrophysiological differences between nociceptive and non-nociceptive dorsal root ganglion neurones in the rat in vivo
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DOI：
10.1113/jphysiol.2005.086199
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发表时间：
2005-06-15
影响因子：
5.5
通讯作者：
Djouhri, L
中科院分区：
文献类型：
--
作者：
Fang, X;McMullan, S;Djouhri, L
对麻醉成年大鼠1022个背根神经节（DRG）神经元进行了细胞内记录，根据背根传导速度（CV）将其分为C、A δ或A α/β，并根据其对机械和热刺激的反应将其分为伤害性反应（包括高阈值机械感受（HTM）单位）和非伤害感受（包括低阈值机械感受（LTM）和冷却单位）。其中，463例符合背根刺激诱发的动作电位（AP）分析的电生理标准。其中包括47个C-、71个A δ和102个A α/β-伤害感受性，10个C-、8个A δ-和178个A α/β-LTM，18个C-和19个A δ无反应，4个C-冷却单位。AP和后超极化（AHP）的持续时间和AP过冲的中位数显着大于伤害性比LTM单位在所有CV组。AP过冲和AHP持续时间在伤害感受器中相似;所有CV组中，AP持续时间在缓慢传导，尤其是C纤维，伤害感受器中更大。C-冷却装置比C-HTM装置具有更快的CV、更小的AP过冲和更短的AP持续时间。AC α/β-HTM的一个亚组，中等压力单位，比其他A α/β-HTM单位具有更快的CV和AP动力学。在A α/β-LTM单位中，肌梭传入具有最快的CV和AP动力学，而快速适应皮肤单位具有最慢的AP动力学。无反应和伤害性单位的AP变量在C和A δ纤维CV组中相似。纤维的能力，以遵循快速刺激列车（纤维的最大频率）与CV，但不感觉modernization.These研究结果表明，使用电生理标准识别神经元急性在体外伤害性的有用性和局限性。
Intracellular recordings were made from 1022 somatic lumbar dorsal root ganglion (DRG) neurones in anaesthetized adult rats, classified from dorsal root conduction velocities (CVs) as C, A delta or A alpha/beta, and according to their responses to mechanical and thermal stimuli as nociceptive (including high-threshold mechanoreceptive (HTM) units), and non-nociceptive (including low-threshold mechanoreceptive (LTM) and cooling units). Of these, 463 met electro-physiological criteria for analysis of action potentials (APs) evoked by dorsal root stimulation. These included 47 C-,71 A delta and 102 A alpha/beta-nociceptive, 10 C-, 8 A delta - and 178 A alpha/beta-LTM, 18 C- and 19 A delta unresponsive, and 4 C-cooling units. Medians of AP and afterhyperpolarization (AHP) durations and AP overshoots were significantly greater for nociceptive than LTM units in all CV groups. AP overshoots and AHP durations were similar in nociceptors; of all CV groups whereas AP durations were greater in slowly conducting, especially C-fibre, nociceptors. C-cooling units had faster CVs, smaller AP overshoots and shorter AP durations than C-HTM units. A subgroup of Ac alpha/beta-HTM, moderate pressure units, had faster CVs and AP kinetics than other A alpha/beta-HTM units. Of the A alpha/beta-LTM units, muscle spindle afferents had the fastest CV and AP kinetics, while rapidly adapting cutaneous units had the slowest AP kinetics. AP variables in unresponsive and nociceptive units were similar in both C- and A delta-fibre CV groups. The ability of fibres to follow rapid stimulus trains (fibre maximum following frequency) was correlated with CV but not sensory modality.These findings indicate both the usefulness and limitations of using electrophysiological criteria for identifying neurones acutely in vitro as nociceptive.