Miki K, Iwata K, Tsuboi Y, Morimoto T, Kondo E, Dai Y, Ren K, Noguchi K
Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo, Japan.
Pain. 2000 Mar;85(1-2):263-71. doi: 10.1016/s0304-3959(99)00279-1.
A total of 68 neurons were recorded from the ventro-postero-lateral nucleus of thalamus (VPL) in rats with a unilateral chronic constriction injury (CCI) of the sciatic nerve (n=20), sham operation (n=24) and naive rats (n=24), and effects of the lesion of dorsal column (DC) pathway [DC lesion or DC+gracile nucleus lesions] on VPL nucleus neuronal activities were studied. In the VPL nucleus contralateral to the CCI (receiving input from the injured nerve), response latencies of low threshold mechanoreceptive (LTM) and wide dynamic range (WDR) neurons to electrical stimulation of the sciatic nerve were significantly longer than that in the contralateral VPL nucleus receiving input from the sham-operated side (P<0.05). In contrast, response latencies of LTM and WDR neurons to DC stimulation were not different between the sham operated and CCI sides (0.05). Background activity of WDR neurons was significantly higher in the VPL nucleus contralateral to the CCI side when compared to neurons in the VPL nucleus contralateral to the sham operated side and in naive animals. Responses of LTM and WDR neurons to innocuous mechanical stimulation of the receptive fields were significantly decreased after DC and DC+gracile nucleus lesions in all animals. However, the responses of WDR neurons to noxious stimuli were selectively reduced only in rats with CCI by DC and DC+gracile nucleus lesions (P<0.05). The decrease in noxious stimulus-evoked responses of WDR neurons in the VPL nucleus contralateral to the CCI side after DC and DC+gracile nucleus lesions was greater than that in the VPL nucleus contralateral to the sham operated side and naive animals. These results indicated that DC and DC+gracile nucleus lesions produced selective and stronger effect on noxious responses of VPL nucleus WDR neurons receiving input from the site of nerve injury. The findings suggest that the gracile nucleus-thalamic pathway conveys, or modulates, nociceptive information to the VPL nucleus following peripheral nerve injury, resulting in an increase in VPL nucleus response to noxious stimuli that contributes to the development of mechanical hyperalgesia.
在坐骨神经单侧慢性压迫损伤（CCI）大鼠（n = 20）、假手术大鼠（n = 24）和正常大鼠（n = 24）中，共记录了68个丘脑腹后外侧核（VPL）的神经元，并研究了背柱（DC）通路损伤[DC损伤或DC + 薄束核损伤]对VPL核神经元活动的影响。在与CCI相对侧的VPL核（接收来自损伤神经的输入）中，低阈值机械感受性（LTM）和广动力范围（WDR）神经元对坐骨神经电刺激的反应潜伏期明显长于接收来自假手术侧输入的对侧VPL核（P < 0.05）。相反，假手术侧和CCI侧的LTM和WDR神经元对DC刺激的反应潜伏期没有差异（P>0.05）。与假手术侧对侧VPL核中的神经元以及正常动物相比，CCI侧对侧VPL核中WDR神经元的背景活动明显更高。在所有动物中，DC和DC + 薄束核损伤后，LTM和WDR神经元对感受野无害机械刺激的反应明显降低。然而，仅在CCI大鼠中，DC和DC + 薄束核损伤选择性地降低了WDR神经元对有害刺激的反应（P < 0.05）。DC和DC + 薄束核损伤后，CCI侧对侧VPL核中WDR神经元有害刺激诱发反应的降低大于假手术侧对侧VPL核和正常动物。这些结果表明，DC和DC + 薄束核损伤对接收来自神经损伤部位输入的VPL核WDR神经元的有害反应产生了选择性和更强的影响。这些发现表明，薄束核 - 丘脑通路在周围神经损伤后将伤害性信息传递或调节至VPL核
