Lewis Susannah S, Grace Peter M, Hutchinson Mark R, Maier Steven F, Watkins Linda R
Department of Psychology & Neuroscience, University of Colorado, Boulder, USA.
Department of Psychology & Neuroscience, University of Colorado, Boulder, USA; School of Medicine, University of Adelaide, Adelaide, Australia.
Brain Behav Immun. 2017 Aug;64:59-64. doi: 10.1016/j.bbi.2016.12.004. Epub 2016 Dec 18.
Despite pain being a sensory experience, studies of spinal cord ventral root damage have demonstrated that motor neuron injury can induce neuropathic pain. Whether injury of cranial motor nerves can also produce nociceptive hypersensitivity has not been addressed. Herein, we demonstrate that chronic constriction injury (CCI) of the buccal branch of the facial nerve results in long-lasting, unilateral allodynia in the rat. An anterograde and retrograde tracer (3000MW tetramethylrhodamine-conjugated dextran) was not transported to the trigeminal ganglion when applied to the injury site, but was transported to the facial nucleus, indicating that this nerve branch is not composed of trigeminal sensory neurons. Finally, intracisterna magna injection of interleukin-1 (IL-1) receptor antagonist reversed allodynia, implicating the pro-inflammatory cytokine IL-1 in the maintenance of neuropathic pain induced by facial nerve CCI. These data extend the prior evidence that selective injury to motor axons can enhance pain to supraspinal circuits by demonstrating that injury of a facial nerve with predominantly motor axons is sufficient for neuropathic pain, and that the resultant pain has a neuroimmune component.
尽管疼痛是一种感觉体验，但对脊髓腹侧神经根损伤的研究表明，运动神经元损伤可诱发神经性疼痛。颅运动神经损伤是否也会产生伤害性超敏反应尚未得到探讨。在此，我们证明面神经颊支的慢性压迫损伤（CCI）会导致大鼠出现持久的单侧异常性疼痛。当将顺行和逆行示踪剂（3000MW 四甲基罗丹明偶联葡聚糖）应用于损伤部位时，它不会运输到三叉神经节，但会运输到面神经核，这表明该神经分支不是由三叉神经感觉神经元组成。最后，经小脑延髓池注射白细胞介素-1（IL-1）受体拮抗剂可逆转异常性疼痛，这表明促炎细胞因子 IL-1 参与了面神经 CCI 诱导的神经性疼痛的维持。这些数据扩展了先前的证据，即通过证明主要为运动轴突的面神经损伤足以导致神经性疼痛，以及由此产生的疼痛具有神经免疫成分，从而表明对运动轴突的选择性损伤可增强对脊髓上回路的疼痛感受。
