Bigbee Allison J, Akhavan Mahnaz, Havton Leif A
Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States.
Department of Molecular, Cell, and Developmental Biology, UCLA, Los Angeles, CA, United States.
Front Neurol. 2017 Jul 31;8:291. doi: 10.3389/fneur.2017.00291. eCollection 2017.
Injuries to the conus medullaris and cauda equina portions of the spinal cord result in neurological impairments, including paralysis, autonomic dysfunction, and pain. In experimental studies, earlier investigations have shown that a lumbosacral ventral root avulsion (VRA) injury results in allodynia, which may be ameliorated by surgical replantation of the avulsed ventral roots. Here, we investigated the long-term effects of an L6 + S1 VRA injury on the plasticity of three populations of afferent projections to the dorsal horn in rats. At 8 weeks after a unilateral L6 + S1 VRA injury, quantitative morphological studies of the adjacent L5 dorsal horn showed reduced immunoreactivity (IR) for the vesicular glutamate transporter, VGLUT1 and isolectin B4 (IB4) binding, whereas IR for calcitonin gene-related peptide (CGRP) was unchanged. The IR for VGLUT1 and CGRP as well as IB4 binding was at control levels in the L5 dorsal horn at 8 weeks following an acute surgical replantation of the avulsed L6 + S1 ventral roots. Quantitative morphological studies of the L5 dorsal root ganglia (DRGs) showed unchanged neuronal numbers for both the VRA and replanted series compared to shams. The portions of L5 DRG neurons expressing IR for VGLUT1 and CGRP, and IB4 binding were also the same between the VRA, replanted, and sham-operated groups. We conclude that the L5 dorsal horn shows selective plasticity for VGLUT1 and IB4 primary afferent projections after an L6 + S1 VRA injury and surgical repair.
脊髓圆锥和马尾部位的损伤会导致神经功能障碍，包括瘫痪、自主神经功能障碍和疼痛。在实验研究中，早期调查表明腰骶部腹侧神经根撕脱（VRA）损伤会导致异常性疼痛，而撕脱的腹侧神经根的手术再植可能会改善这种情况。在此，我们研究了L6 + S1 VRA损伤对大鼠背角传入投射的三个群体可塑性的长期影响。在单侧L6 + S1 VRA损伤后8周，对相邻L5背角的定量形态学研究显示，囊泡谷氨酸转运体VGLUT1的免疫反应性（IR）降低，异凝集素B4（IB4）结合减少，而降钙素基因相关肽（CGRP）的IR不变。在撕脱的L6 + S1腹侧神经根急性手术再植后8周，L5背角中VGLUT1和CGRP以及IB4结合的IR处于对照水平。对L5背根神经节（DRG）的定量形态学研究显示，与假手术组相比，VRA组和再植组的神经元数量均未改变。VRA组、再植组和假手术组之间，表达VGLUT1和CGRP的IR以及IB4结合的L5 DRG神经元部分也相同。我们得出结论，L6 + S1 VRA损伤和手术修复后，L5背角对VGLUT1和IB4初级传入投射表现出选择性可塑性。
