坐骨神经结扎后大鼠背根神经节和脊髓CGRP表达的变化

目的研究大鼠坐骨神经结扎后降钙素基因相关肽(calcitoningene-relatedpeptide,CGRP)表达变化。方法SD大鼠随机分为假手术对照组和坐骨神经结扎组,实验组结扎后分别存活1、3、5、7、14、21和28d(n=8),免疫荧光(双标法)和免疫组织化学(SABC法)观察术后不同时间点CGRP和NGF在坐骨神经、背根神经节(dorsalrootganglion,DRG)和脊髓的表达变化,Westernblot结合图像分析技术对不同时间的变化进行定量测定。结果术后1d结扎远端坐骨神经内NGF大量堆积,持续到28d仍高于正常。结扎后7dDRG内CGRP阳性细胞百分率减少,持续到28d仍低于正常;结扎后14d脊髓后角CGRP下降,28d仍低于正常,各时间点脊髓前角CGRP表达未见明显变化。结论神经结扎可导致DRG和脊髓后角的CGRP表达下调,可能与靶源性的NGF来源减少有关。

CHANGES IN THE EXPRESSION OF CALCITONIN GENE-RELATED PEPTIDE IN DORSAL ROOT GANGLION AND SPINAL CORD OF RATS AFTER SCIATIC NERVE LIGATION

Objective To investigate the experssion of calcitonin gene-related peptide(CGRP) in dorsal root ganglion (DRG) and spinal cord of rats after sciatic nerve ligation. Methods 64 Sprague-Dawley rats were randomly divided into sham-operation and sciatic nerve ligtion groups, and the latter were further divided into seven subgroups of different survival periods (1,3,5,7,14,21,and 28 d) (n=8). The changes in the experssion of CGRP and nerve growth factor(NGF) in sciatic nerve, L_ 4-6 DRG, and spinal cord were detected by double immunofluorescence and avidin-biotin complex staining. Quantitative analysis using Western blot combined with image analysis was also performed.Results On the day 1 after ligation there was an accumulation of NGF-like immunoreactive products in distal segments, which lasted 28 days. The percentage of CGRP-immunoreactive neuronsinDRG started to drop on the day 7, and still remained lower than normal after 28 d. The CGRP-immunoreactivity in the ipsilateral spinal dorsal horn decreased significantly after 14d and remained lower after 28 d. There wereno significant changes of the CGRP-positive spinal ventral motoneurons in all experimental animals. Conclusion Sciatic nerve ligation can induce a decline of CGRP expression in DRG and spinal cord,which might be related to the deficiency of NGF derived from target organs.