Miki Kenji, Iwata Koichi, Tsuboi Yoshiyuki, Sumino Rhyuji, Fukuoka Tetsuo, Tachibana Toshiya, Tokunaga Atsushi, Noguchi Koichi
Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan Department of Physiology, School of Dentistry Nihon University, 1-8-13 Kandasurugadai, Chiyoda-ku, Tokyo 101-8310, Japan.
Pain. 1998 Jun;76(3):407-415. doi: 10.1016/S0304-3959(98)00073-6.
To examine the functional role of dorsal column nuclei in neuropathic pain, electrophysiological properties of low- and high-threshold dorsal column nuclei neurons in neuropathic and normal rats were examined. Single-neuronal activities were recorded from the gracile nucleus (GN) in rats at 10-14 days after application of four loose ligatures around the sciatic nerve (chronic constriction nerve injury; CCI). A total of 190 units were recorded from the GN in naive and CCI rats. The largest population of low-threshold mechanoreceptive (LTM) neurons recorded from the GN of naive rats were classified as rapidly-adapting (RA) LTM neurons, whereas those from CCI rats were slowly-adapting (SA) neurons. Mean orthodromic latencies of GN neurons ipsilateral to the CCI after sciatic nerve stimulation were significantly longer than those of naive animals and those of GN neurons without receptive fields were significantly longer than any other type of neurons. One hundred and eight of 190 GN neurons were also antidromically activated following electrical stimulation of the ventro-lateral posterior nucleus of the thalamus. Furthermore, when stronger stimuli were applied to the sciatic nerve, some GN neurons also responded with long latencies. GN neurons of sham-operated naive rats and those contralateral to the CCI had mechanical receptive fields on the paw, whereas 8.0% of the GN neurons in the CCI side did not have any detectable mechanical receptive field. Receptive field size was not significantly different between neurons ipsilateral or contralateral to the CCI and those of naive rats. Spontaneous activity of GN neurons from the ipsilateral side was significantly higher than those from the contralateral side. On the other hand, spontaneous activity of GN neurons both ipsilateral and contralateral to the CCI were significantly higher than those from naive rats. Furthermore, afterdischarges of GN neurons ipsilateral and contralateral to the CCI were significantly higher than those of naive rats. The present data suggest that the dorsal column pathway is involved in CCI-produced sensory abnormalities by conveying their hyperactivity to thalamic neurons.
为研究背柱核在神经性疼痛中的功能作用，我们检测了神经病理性大鼠和正常大鼠中低阈值和高阈值背柱核神经元的电生理特性。在坐骨神经周围进行四处宽松结扎（慢性压迫性神经损伤；CCI）后10 - 14天，记录大鼠薄束核（GN）的单神经元活动。在未处理大鼠和CCI大鼠的GN中共记录到190个单位。从未处理大鼠的GN记录到的最大群体的低阈值机械感受性（LTM）神经元被分类为快速适应（RA）LTM神经元，而从CCI大鼠记录到的则是缓慢适应（SA）神经元。坐骨神经刺激后，CCI同侧GN神经元的平均顺向潜伏期显著长于未处理动物，且无感受野的GN神经元的潜伏期显著长于其他任何类型的神经元。在对丘脑腹后外侧核进行电刺激后，190个GN神经元中有108个也被逆向激活。此外，当对坐骨神经施加更强刺激时，一些GN神经元也会出现长潜伏期反应。假手术未处理大鼠和CCI对侧的GN神经元在爪上有机械感受野，而CCI侧8.0%的GN神经元没有任何可检测到的机械感受野。CCI同侧或对侧的神经元与未处理大鼠的神经元之间，感受野大小无显著差异。同侧GN神经元的自发活动显著高于对侧。另一方面，CCI同侧和对侧GN神经元的自发活动均显著高于未处理大鼠。此外，CCI同侧和对侧GN神经元的后放电均显著高于未处理大鼠。目前的数据表明，背柱通路通过将其过度活动传递给丘脑神经元，参与了CCI引起的感觉异常。
