大鼠坐骨神经损伤对背根节GDNF的表达的影响

目的 应用免疫组化技术观察大鼠坐骨神经条件性损伤对相应背根节及坐骨神经胶质细胞源性神经营养因子（glial cell line-derived neurotrophic factor,GDNF)表达的影响，以探讨GDNF对损伤神经元的作用。方法 45只成年雌性Wistar大鼠随机分为3组：A组（N＝5）正常对照组，B组（N＝20）坐骨神经压榨伤组，C组（N＝20）坐骨神经切断／结扎组；B、C两组按存活期不同再各分为4个亚组，每组5例。大鼠分别于伤后3天、2周、1个月、2个月处死，取材L5节段损伤侧背根节及损伤坐骨神经的远近节段，免疫组化染色观测GDNF表达。结果 （1）正常背根节细胞GDNF表达主要分布于小神经元，少数为大神经元。（2）坐骨神经损伤促使同侧背根节神经元GDNF表达显著增强，伤后2周达到高峰；B组背根节细胞GDNF表达在伤后1个月时轻度下调，伤后2个月恢复为对照组水平。C组背根节细胞GDNF表达保持高水平，并至观察后期2个月。（3）坐骨神经损伤同时诱导背根节卫生细胞及坐骨神经雪旺氏细胞，GNDF表达显著增强，其中远端坐骨神经GDNF表达强于近端。B组这些细胞的阳性表达持续至伤后2周，C组伤后1个月时其表达仍显著。结论 GDNF是参与损伤初级感觉神经元反应的重要因子，并可能对正常及受损背根节细胞发挥营养作用。

Experimental study on GDNF expression of dorsal root ganglion in the conditioning lesions of sciatic nerve in rats

Objective To investigate the effect of sciatic nerve injury on the expression of GDNF of dorsal root ganglion(DRG)and sciatic nerve in rats.?Methods Forty five adult female Wistar rats were divided into three groups randomly: group A(n=5) served as control group, B(n=20)were subjected to sciatic nerve crush and group C(n=20) were subjected to sciatic nerve transection/ligtion. The latter two groups were further divided into four subgroups according to different survival periods (3 day, 2 week, 1 month and 2 month), respectively. The rats were sacrificed on above time points respectively. Ipsilateral L5 DRG or proximal and distal segment of injuried sciatic nerve were removed, Immunohistochemical technique was used for detection of the expression of GDNF.?Results (1)?The positive GDNF immunoreactivity was found predominantly in the small neurons of normal DRG;only a few of the large neurons also expressed GDNF weakly.(2)?Sciatic nerve injury induced significantly the expression of GDNF of primary sensory neurons in DRG which reached its peak at 2 weeks postlesion. The expression of GDNF of DRG in group B was reduced slightly at 1 month and reached control level at 2 month postlesion, however,in group C, the expression of GDNF kept at higher level at 2 month observed.(3)? GDNF of Schwann cells was upregulated in the injuried sciatic nerve distally and proximally,but this increase was more modest proximally;?the satellites in DRG was also upregulated GDNF remarkedly.Expression of GDNF in these cells continued 2 weeks in group B and 1 month in group C postlesion respectively.?Conclusion These findings suggest that GDNF is an important factor in the event following adult primary sensory neurons injury and may be involved in the trophic support to these cells.