幻肢痛大鼠脊髓背角神经元和突触数量的变化

Changes in the number of synapses and neurons in spinal dorsal horn in a rat model of phantom limb pain

目的 探讨幻肢痛大鼠脊髓背角神经元和突触数量的变化.方法 健康成年SD大鼠11只,雄雌不拘,体重290～300 g,随机分为2组：假手术组（S组,n=5）和单侧坐骨神经横断组（P组,n=6）.术后持续观察P组大鼠自噬情况,并进行自噬评分.术后28 d时,取L3～6节段脊髓组织,分别进行尼氏染色（显示神经元）和突触素免疫组织化学染色（显示突触数量）,计数手术侧和非手术侧脊髓背角神经元和突触的数量.结果 P组自术后2 d开始陆续发生自噬,自噬评分9～11分.与S组比较,P组各节段双侧脊髓背角神经元数量及L3.6节段脊髓背角突触数量差异无统计学意义（P＞0.05）,手术侧L4.5节段脊髓背角突触数量增加（P＜0.05）.结论 幻肢痛大鼠脊髓背角突触数量增加,神经元数量未发生变化;突触数量增加可诱发幻肢痛.

Objective To investigate the changes in the number of synapses and neurons in the spinal dorsal horn in a rat model of phantom limb pain. Methods Eleven healthy adult SD rats of both sexes weighing 209-300 g were randomly divided into 2 groups： sham operation group （group S, n = 5） and phantom limb pain group （group P, n = 6）. Phantom limb pain was induced by resection of a 0.5 cm segment of unilateral sciatic nerve in group P. In group S unilateral sciatic nerve was exposed but not transected. The animals were observed for autotomy and scored （0 = no autotomy, 13 = the worst autotomy） after operation and were sacrificed on the 28th day after operation. The L3-6 segment of the spinal cord was removed for determination of the number of neurons （by Nissl＇s staining） and synapses （by synaptophysin immuno-histochemistry）.Results In group S no animal developed autotomy. In group P autotomy started from the 2nd day after operation and the score reached 9-11. The number of the neurons in the spinal dorsal horn in all 4 segments and the number of synapses in L3 and 16 segments were comparable between the two sides and the 2 groups. The number of synapses in the spinal dorsal horn of L4and L5 segment was significantly larger in the operated side than in the contralateral side in group P. Conclusion The number of synapses in the spinal dorsal horn significantly increases in animals with plantom limb pain which induces no increase in the number of neurons in the spinal dorsal horn.