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目的:观察降钙素基因相关肽(calcitonin gene-related peptide,CGRP)样阳性终末在L5脊神经结扎模型大鼠脊髓背角浅层内的表达变化。方法:建立大鼠L5脊神经结扎模型(L5 spinal nerve ligation model,SNL),建模后分别在1、3、5、7 d和14 d不同时间点通过von Frey丝检测大鼠后爪的机械性痛敏,然后在大鼠分别存活7 d和14 d时灌注取材,采用免疫组织化学染色结合平均光密度(optical density,OD)分析的方法以及免疫电镜标记技术检测脊髓背角浅层内CGRP样阳性物质的表达变化。结果:(1)行为学结果显示:模型组大鼠的机械性痛敏的阈值明显降低,与正常组比较有显著性差异(p<0.05),提示建模成功;(2)免疫组织化学染色显示:正常大鼠脊髓背角浅层内存在大量密集分布的CGRP样阳性终末,主要分布于脊髓背角的I层和II层。SNL模型大鼠在结扎7 d和14 d后脊髓背角浅层内CGRP样阳性产物的表达明显增多,其平均OD值分别为38.30±3.11和35.70±2.36,与正常对照组(25.10±2.30)比较,具有显著性差异(P<0.05);(3)电镜结果显示:CGRP样免疫活性物质只分布于轴突终末内,且主要与树突结构形成非对称性突触。结论:CGRP样免疫阳性物质在SNL模型大鼠脊髓背角浅层内的表达增加,提示CGRP样阳性终末在伤害性信息的传递中具有重要作用。
Objective: To observe the expression changes of calcitonin gene-related peptide (CGRP) -like terminals in the superficial layers of dorsal horn of spinal cord in L5 spinal nerve ligation rats. Methods: The rat L5 spinal nerve ligation model (SNL) was established. The mechanical properties of rat hind paws were detected by von Frey wires at different time points after 1, 3, 5, 7 d and 14 d Pain-sensitive, and then in rats were survival for 7 d and 14 d perfusion material, immunohistochemical staining combined with the average optical density (optical density, OD) analysis methods and immunoelectron microscopy markers in spinal dorsal horn CGRP-like Changes in the expression of positive substances. Results: (1) The results of behavioral study showed that the threshold of mechanical hyperalgesia in model group was significantly lower than that in normal group (p <0.05), suggesting that the modeling was successful; (2) Immunohistochemical staining The results showed that there were a large number of dense CGRP-like positive terminals in the superficial layers of spinal dorsal horn of normal rats, which were mainly distributed in the I and II layers of spinal dorsal horn. In the SNL model rats, the expression of CGRP-like products in the superficial layers of dorsal horn of spinal cord increased significantly after 7 and 14 days of ligation, with the average OD values of 38.30 ± 3.11 and 35.70 ± 2.36, respectively, compared with those of the normal control group (25.10 ± 2.30) (P <0.05). (3) Electron microscopy results showed that CGRP-like immunoreactive substance only distributed in the terminal of axon, and mainly formed asymmetric synapse with dendritic structure. CONCLUSION: The expression of CGRP-like immunoreactive substance in the superficial layer of dorsal horn of SNL model rats increased, suggesting that CGRP-like positive terminals play an important role in the transmission of nociceptive information.