部分背根切断对备用背根节和脊髓IGF—I表达的影响

目的探讨IGF—I在正常猫和部分去背根猫的L6双侧背根节和脊髓Ⅱ板层(L3、L6、L5)与背核(L3)表达及变化，以了解IGF—I与脊髓可塑性的关系。方法成年健康雄猫15只分为正常组、备用根术后7d组与14d组，每组5只。用兔抗IGF—I(1：200)抗体行免疫组化ABC法染色。观察、计数并比较各组背根节、脊髓实验侧I板层(L3、L5、L6)和背核(L3)中IGF—I的分布、含量。结果①IGF—I在去部分背根后7d，术侧背根节阳性细胞数比正常组显著减少(P＜0．05)，与非术侧比无差异(P＞0．05)；术后14d，术侧背根节IGF—I阳性神经元数比正常组亦显著减少(P＜0．05)，与术后7d组比无差异(P＞0．05)，较非术侧者明显减少(P＜0．01)。②各组L3、L5、L6术侧脊髓Ⅱ板层内IGF—I阳性神经元数均无明显差异(P＞0．05)。L。背核IGF—I阳性神经元数在术后两时相则先减少后增加(P＜0．05)，且在术后14d时恢复至正常水平(P＞0．05)。结论部分背根切断导致双侧背根节IGF—I表达改变和脊髓背核IGF—I表达改变，提示IGF—I与脊髓可塑性有关。

The influence of partial dorsal root rhizotomy on IGF-I expression in spared root ganglion and spinal cord]

OBJECTIVE: To explore the temporospatial changes of IGF-I expression 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 adult cats that have undergone partial dorsal rhizotomy, and compare them against those of the normal adult cats so as to unveil the relation between IGF-I and the plasticity of spinal cord. METHODS: Fifteen male adult cats were divided into three groups. The cats of two groups were subjected to unilateral partial dorsal root rhizotomy (L1-L5, L7-S2 DRG were sectioned, but L6 was spared) and were sacrificed at 7 days and 14 days after operation. The bilateral L6 dorsal root ganglia and L3, L5, L6 spinal cord of all groups were made into frozen sections 20 microm thick. Then, the sections were stained by the immunohistochemistry ABC method using IGF-I (1:200, Santa Cruz) antibody. The distribution and the number of IGF-I positive neurons in bilateral spared DRG (L6) on the operated/un-operated side, in spinal lamina I (L3, L5, L6) and in Clarke' 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 IGF-I positive neurons in spared DRG on the operated side declined as compared with that of normal group (P<0.05), but it was not significantly different from that of L6 spared DRG on the un-operated side (P>0.05). On the 14th day, the IGF-I expression in neurons of L6 DRG on the operated side was significantly lower than that of normal group and that of L6 spared DRG on the unoperated side (P<0.01), but it was not significantly different from that of the 7th day group (P>0.05). (2) There was no difference in number of IGF-I positive neuron in L3, L5, L6 spinal lamina II between normal group, 7th day post-operation group and 14th day post-operation group (P>0.05). After operation, IGF-I expression in Clarke's nucleus declined on the 7th day (P<0.05) and came back to normal level on the 14th day (P>0.05). CONCLUSION: Partial dorsal root rhizotomy can lead to the change of IGF-I expression in bilateral DRG and Clarke's nucleus, which suggests that IGF-I be related with spinal cord plasticity.