部分去背根猫Sema3A及其受体NP-1在脊髓和背根节的表达

目的研究部分去背根对神经生长抑制因子Sema3A在脊髓及其受体NP-1在备用背根节内表达的影响。方法建立猫的单侧备用背根模型,分别在术后7d、14d取L3、L5、L6脊髓节段及手术侧L6背根节进行免疫组织化学ABC法染色,同时设置正常对照组。脊髓背角内检测Sema3A免疫阳性产物的平均光密度值(OD值),背根节内计数NP-1阳性中小神经元数。结果在L3脊髓节段,Sema3A的表达术后7d(0.25±0.14)、14d(0.27±0.09)较正常对照组(0.37±0.87)减弱(P<0.05);在L5脊髓节段,Sema3A的表达术后7d(0.26±0.11)较正常组减弱(P<0.05),术后14d(0.33±0.09)时有所恢复;L6脊髓节段各组Sema3A的表达无明显变化。背根节内,术后7dNP-1阳性中小神经元数(30.85±10.26)较正常组(45.06±12.47)减少(P<0.05),14d时阳性中小神经元数(40.73±12.25)较7d时有所增加(P<0.05)。结论脊髓部分去背根后,Sema3A及其受体NP-1表达的时空变化可能与脊髓损伤后可塑性有关。

Expression of Sema3A and NP-1 in Spinal Cord and Spared Dorsal Root Ganglion after Partial Dorsal Root Rhizotomy of Cat

OBJECTIVE: To investigate the expression of semaphorin 3A (Sema3A) and neuropilin 1 (NP-1) in spinal cord and dorsal root ganglion after partial dorsal root rhizotomy. METHODS: 15 adult cats were used for this study and divided into 3 groups: normal control group, 7 d and 14 d postoperative groups (7Th day and 14th day groups) undergoing unilateral partial dorsal root rhizotomy. The L3, L5 and L6 segments of spinal cord and L6 dorsal root ganglia (DRG) in operated side were made into frozen sections. By immunohistochemistry ABC method, the sections of spinal cord were stained with specific Sema3A antibody, and L6 DRG were stained with NP-1 antibody. The mean optical density (OD) of Sema3A immunoreactivity in dorsal horn was measured and the number of NP-1 positive medium-small sized neurons in spared DRG was counted. RESULTS: After partial dorsal root rhizotomy, in L3 segment the expression of Sema3A decreased in 7th day group (0.25 +/- 0. 14) compared with that in normal group(0. 37 +/- 0.87) (P < 0.05), but kept the level along to 14th day group (0.27 +/- 0.09); in L5 segment, the expression of Sema3A decrea sed in 7th day group (0.26 +/- 0.11) (P < 0.05), and then recovered to normal level in 14th day group (0.33 +/- 0.09); in L6 segment, OD values in dorsal horn had no changes to all groups. The number of NP-1 positive medium-small sized neurons in spared DRG (30.85 +/- 10.26) was decreased in 7th day group (P < 0.05), compared with that in normal group (45.06 +/- 12.47), while increased in 14th day group (P < 0.05). CONCLUSION: Changes in the expression of Sema3A in spinal cord and the expression of NP-1 in L6 DRG after partial root rhizotomy may be involved in collateral sprouting of spared root in superficial lamina.