Gorodetskaya Natalia, Constantin Cristina, Jänig Wilfrid
Physiologisches Institut, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, 24098 Kiel, Germany.
Eur J Neurosci. 2003 Nov;18(9):2487-97. doi: 10.1046/j.1460-9568.2003.02974.x.
Spontaneous activity, and mechanical and thermal sensitivity were investigated in regenerating afferent nerve fibers within 4-21 days post sural nerve lesion (crush or transection and resuturing) in anaesthetized rats. About 33-40% of the myelinated (A) and 22-27% of the unmyelinated (C) fibers excited by electrical nerve stimulation exhibited at least one of these ectopic discharge properties. In total 177 A- and 169 C-fibers with ectopic activity were analysed. Most A-fibers (161/177) were mechanosensitive. Spontaneous activity (median 1 imp/s) was present in 23/177 and thermosensitivity in 14/177 A-fibers (13 of them being activated by heat stimuli). Almost all A-fibers (159/177) exhibited only one type of ectopic discharge property. Most C-fibers (94/169) were thermosensitive responding either to cold (n = 45) or to heat stimuli (n = 33) or to both (n = 16). Eighty-four of 169 C-fibers were spontaneously active (median 0.3 imp/s) and 75/169 C-fibers were mechanosensitive. Both the proportion and the discharge rate of spontaneously active C-fibers were significantly higher after crush than after section and resuturing of the nerve. About 60% of the C-fibers (101/169) had only one ectopic discharge property and 40% two or three. In conclusion, regenerating cutaneous afferent A- and C-fibers may develop mechano- and/or thermosensitivity as well as spontaneous activity. We suggest that spontaneous and evoked ectopic activity in regenerating cutaneous afferents are a function of the intrinsic functional properties of these neurons and of the interaction between the regenerating nerve fibers and non-neural cells during Wallerian degeneration in the nerve distal to the nerve lesion.
在麻醉大鼠的腓肠神经损伤（挤压或横断并缝合）后4 - 21天内，对再生传入神经纤维的自发活动、机械敏感性和热敏感性进行了研究。经电神经刺激激发的有髓（A）纤维中约33 - 40%以及无髓（C）纤维中22 - 27%表现出至少一种这些异位放电特性。总共分析了177条具有异位活动的A纤维和169条C纤维。大多数A纤维（161/177）对机械刺激敏感。23/177的A纤维存在自发活动（中位数为1次冲动/秒），14/177的A纤维具有热敏感性（其中13条被热刺激激活）。几乎所有A纤维（159/177）仅表现出一种类型的异位放电特性。大多数C纤维（94/169）对热刺激敏感，对冷刺激（n = 45）、热刺激（n = 33）或两者都有反应（n = 16）。169条C纤维中有84条自发活动（中位数为0.3次冲动/秒），75/169的C纤维对机械刺激敏感。挤压神经后，自发活动的C纤维比例和放电率均显著高于神经横断并缝合后。约60%的C纤维（101/169）仅具有一种异位放电特性，40%具有两种或三种。总之，再生的皮肤传入A纤维和C纤维可能会产生机械和/或热敏感性以及自发活动。我们认为，再生皮肤传入纤维中的自发和诱发异位活动是这些神经元内在功能特性以及神经损伤远端神经沃勒变性过程中再生神经纤维与非神经细胞之间相互作用的结果。
