部分背根切断对备用背根节和脊髓NT-4表达的影响

目的探讨NT-4在正常猫和部分去背根猫的L6背根节(手术侧和非手术侧)和脊髓Ⅱ板层与背核表达的变化。方法成年健康雄猫15只分为正常组、备用根术后7d组和14d组(动物行单侧部分去背根手术，即切除一侧L1-L5、L7-S2背根节，保留L6为备用根)，采用免疫组化ABC法，观察、计数各组背根节、脊髓实验侧Ⅱ板层(L3、L5、L6)和背核(L3)中NT-4的分布及含量。结果①去部分背根后7d，备用背根节(术侧)中NT-4阳性神经元数比正常组显著减少（P＜0．05)，但较非术侧明显增多(P＜0．05)；至术后14d，术侧备用背根节NT-4阳性神经元比正常组、7d组和非术侧均减少(P＜0．05)。②正常组、术后两时相L3、L5、L6术侧脊髓Ⅱ板层和L3背核内NT-4阳性神经元数均无明显变化。结论去部分背根主要导致备用背根节NT-4的表达发生变化。

The Changes of NT-4 Expression in Spared Root Ganglion and Spinal Cord Following Partial Dorsal Root Rhizotomy

OBJECTIVE: This study was conducted to detect the expression levels of NT-4 in the spared dorsal root ganglia (DRG, L6) on the operated side and un-operated side, in the spinal lamina II (L3, L5, L6) and Clarke's nucleus (L3) of the normal adult cats and the cats submitted to partial dorsal rhizotomy. The aim was to illuminate the temporospatial changes of NT-4 expression and its possible relation to spinal cord plasticity. METHODS: Fifteen male adult cats were divided into three groups. The cats of two groups were submitted to unilateral partial dorsal root rhizotomy (L1-L5, L7-S2 DRG were sectioned, but L6 was spared) and animals were sacrificed at survived 7 days and 14 days after operation. The sections were stained by the immunohistochemistry ABC method under the same condition, using NT-4 (1:200, Santa Cruz) antibody. The distribution and the number of NT-4 positive neurons in bilateral spared DRG (L6) in the operated/un-operated side, spinal lamina II (L3, L5, L6) and Clarke's nucleus (L3) of each animal were observed and counted. All data were analyzed by one-way ANOVA, SNK-q test and paired-t test. RESULTS: (1) Seven days after partial dorsal root rhizotomy, the number of NT-4 positive neurons in spared DRG in the operated side was significantly less than that of normal group (P<0.05), but significantly more than that of L6 DRG in the unoperated side (P<0.05); the number of NT-4 positive neurons of L6 DRG on the 14th day after partial dorsal root rhizotomy was also less than that of normal group, 7-day group, and the un-operated side (P<0.05). (2) There was no difference in respect to the number of NT-4 positive neuron in L3, L5, L6 spinal lamina II and L3 Clarke's nucleus in the operated side between the normal group, 7-day operation group and 14-day operation group (P>0.05). CONCLUSION: Our results suggest that partial dorsal root rhizotomy can mainly lead to the change of NT-4 expression in the spared root ganglion, and NT-4 in the unoperated side DRG are involved in spinal cord plasticity.