外源性NGF对大鼠坐骨神经切断缝合术后脊髓和背根节CGRP表达的影响

观察外源性神经生长因子(NGF)对坐骨神经切断立即缝合后大鼠脊髓和背根节(DRG)内不同时间点降钙素基因相关肽(CGRP)表达的影响。成年SD雄性大鼠随机分为NGF组、生理盐水(NS)组、假手术组与正常对照组。实验组动物右侧坐骨神经切断后立即缝合,每天给予NGF(400单位/kg腹腔注射),动物分别存活1、3、5、7、14、21、28d,免疫组织化学方法结合图像分析检测相应节段脊髓和背根节内CGRP的表达。结果表明,NGF处理组术侧背根节与脊髓后角内的CGRP表达明显高于同时间点的NS对照组,平均光密度值相比P<0.05。但各组中脊髓前角运动神经元内的CGRP表达没有明显变化(P>0.05)。结果提示外源性的NGF能明显增加损伤后背根节感觉神经元与损伤侧脊髓后角的CGRP表达,对CGRP在脊髓前角运动神经元内的表达没有明显影响。

EFFECT OF EXOGENOUS NGF ON THE EXPRESSION OF CGRP IN SPINAL CORD AND DORSAL ROOT GANGLION AFTER SUTURING TRANSECTED SCIATIC NERVE IN RAT

The present study was designed to investigate the effect of exogenous nerve growth factor (NGF) on the expression of calcitonin gene-related peptide (CGRP) in dorsal root ganglion(DRG)and spinal cord after suturing transected rat sciatic nerve immediately. Adult male SD rats (n=110) were divided randomly into NGF, normal saline(NS), sham and normal groups. Rats in NGF group were injected exogenous NGF(400 U/kg.wt) every day after suturing transected right sciatic nerve. The rats were allowed to survive for 1, 3, 5, 7, 14, 21 and 28 d after operation. Immunohistochemical staining and image analysis techniques were used to detect the expression of CGRP in ipsilateral DRG and spinal cord. The result shows that in NGF group, NGF treatment induced an increase of CGRP expression in ipsilateral sensory neurons of DRG and the dorsal horn of spinal cord at different time points, and there was a statistic difference in the mean optical density compared with other groups (P<0.05). On the contrary, there was no change in the expression of CGRP in the ventral horn of spinal cord after application of NGF (P>0.05). Our results suggest that exogenous NGF can up-regulate the expression of CGRP in DRG and the dorsal horn of spinal cord after suturing transected sciatic nerve immediately, but no effect on the expression of CGRP in the ventral horn of spinal cord.