部分背根切断对备用背根节GDNF、FGF-2表达的影响

目的 探讨部分背根切断后不同时相备用背根节(DRG)中胶质细胞源性神经营养因子(GDNF)、成纤维细胞神经生长因子(FGF-2)的表达变化。方法 15只猫分正常组、单侧部分背根切断7d及14d组，每组5只。分别于术后7d、14d处死动物，取正常组一侧、模型组手术侧L6DRG，用兔抗GDNF、FGF-2抗体行免疫组化ABC法染色，计数DRG内两因子阳性总细胞及阳性大、中小细胞的数量。结果 GDNF在正常猫DRG大、中小细胞均有分布；去部分背根后，两时相备用DRG GDNF阳性神经元总数均有下降且呈进行性递减。DRG阳性中小细胞数亦为术后两时相进行性下降，DRG阳性大神经元术后两时相均较正常组显著减少，但术后14d与术后7d组无显著性差异。FGF-2在脊髓DRG大、中小细胞亦有分布;去部分背根后7d，FGF-2阳性神经元总数下降，14d时又恢复至正常，中小细胞亦表现为先减少后上升的趋势，而大细胞则术后两时相与正常组间无显著差异。结论 去部分背根手术可致备用DRG中GDNF阳性神经元总数进行性下降，FGF-2表现为术后7d下降，14d时恢复。

Effect of Partial Dorsal Root Rhizotomy on Expression of GDNF and FGF-2 in Spared Dorsal Root Ganglia

OBJECTIVE: To explore the temporal change on the expression of GDNF and FGF-2 in spared dorsal root ganglia after partial dorsal root rhizotomy. METHODS: Fifteen cats were divided into the normal group, and the partial dorsal root rhizotomy groups. The partial dorsal root rhizotomy groups were sacrificed on day 7 or 14 and the L6 dorsal root ganglia were taken out from each animal and were made into frozen sections 20 microm in thickness respectively. The sections were stained under the same condition using specific GDNF (1 : 500) and FGF-2 (1 : 500) antibody by ABC method. The GDNF and FGF-2 positive large-sized, and medium-small-sized neurons in DRG were counted in each group. All data were analyzed by q test. RESULTS: GDNF immunoreactivity was observed in both large-sized and medium-small-sized DRG neurons. The number of total positive neurons decreased 7 days after partial dorsal root rhizotomy, and was still small after 14 days. Interestingly, the tendency in the number of positive medium-small-sized DRG neurons was just the same as that of total positive neurons while the positive large sized neurons displayed no difference between the 7th day group and the 14th day group, though the number also decreased after operation. FGF-2 immunoreactivity was noted in both large sized and medium-small-sized DRG neurons. After partial dorsal root rhizotomy, the number of total positive neurons decreased on the 7th day and came back to normal level on the 14th day. The number of positive medium-small sized neurons also showed declination followed by escalation, just the same as that of total positive neurons while the number of positive large-sized neurons exhibited no difference between the normal group and the rhizotomy groups. CONCLUSION: Partial dorsal root rhizotomy can lead to continuously declination of total GDNF immunoreactive neurons in spared ganglia, till the 14th day. FGF-2 expression showed declination on the 7th day, but returned to normal level on the 14th day after partial dorsal root rhizotomy. These findings indicate that the expression change of GDNF and FGF-2 after partial dorsal root rhizotomy correlates with the plasticity of spinal cord.