SNI模型大鼠脊髓背角N-甲基-D-天冬氨酸受体和降钙素基因相关肽的表达

Changes of Nervronal N-methyl-D-aspartate Recaptors and Calcitonin Gene-related Peptide Expression in the Spinal Dorsal Horn Neuron Following Spared Nerve Injury of Sciatic Nerve in Rats

【目的】观察坐骨神经分支选择结扎切断模型（Spared nerve injury model,SNI）痛阈及脊髓背角N-甲基-D-天冬氨受体（NMDAR）、降钙素基因相关肽（CGRP）表达的变化。【方法】健康雄性SD大鼠27只,体重220-280 g。随机分为3组（n=9）。对照组（C组）;假手术组（sham组）;坐骨神经分支选择结扎切断模型组（SNI组）。在模型制作前1 d和模型制作后14 d内,每组均进行疼痛行为学观察。所有组别均在模型制作后d2、d7、d14天观察行为学改变后分批取材（每批3只）,用免疫组化法观察大鼠L5节段水平脊髓背角NMDAR和CGRP的表达。【结果】与C组和sham组比较,SNI组在SNI术后均出现机械性异常疼痛痛阈降低（P〈0.01）,但热刺激后爪退缩潜伏时间无统计学意义（P〉0.05）;同时SNI组大鼠脊髓背角NMDAR和CGRP免疫阳性产物数量和表达增加（P〈0.01）。【结论】SNI模型大鼠出现典型的疼痛行为学特征时,其脊髓背角NMDAR和CGRP表达也明显增强,并且脊髓背角NMDAR和CGRP的变化趋势大体相同。

[Objective] To investigate expression of N methyl-D-aspartate recaptors（NMDAR） and Calcitonin gene-related peptide （CGRP） in the spinal dorsal horn neurons induced by spared nerve injury of sciatic nerve. [Methods] twenty-seven healthy male Sprague-Dawley rats （220-280 g） were randomly devided into three groups（n=9）： control group（group C） , sham group （group sham）,spared nerve injury model group （ group SNI）. These rats in group SNI which received a lesion of two of the three terminal branchesof the sciatic nerve（tibial and common peroneal nerves） leaving the remaining sural nerve intact. Mechanical allodynia and radiogenic heat pain thresholds of each group were measured on day 1 pre-surgery and on day 1, 2, 7, 14 postsurgery. On day 2, 7, 14 post-surgery 2 hours after pain thresholds observation, the rats of each group were killed in batch （3 rats/batch）, and the L5 spinal cord were dissected for determination of the expression of NMDAR and CGRP using immunohistochemical techniques. [Result]There were significant difference on the statistics in pain threshold in group SNI as comparede with that in group C and group sham（ P 〈0.01） on days 14 post-surgery, but the radiant heat stimulus paw withdrawal latency was no change in SNI group comparede with that in group C and group sham（ P 〉0.05）. The expression of NMDAR and CGRP immunoreactive soma in the superficial laminae of the L- spinal dorsal horn was significantly increased in group SNI than that in group C and group sham（ P 〈0. 01）. [Conclusion] Hyperpathia may be caused in the injured side limbs of rats following spared nerve injury of sciatic nerve. Simultaneously, neuronal NMDAR and CGRP expression may be significantly increased in rat spinal dorsal horn .