嗅球损伤对脑室下区神经干细胞增殖、迁移和分化的影响

Effect of olfactory bulb lesion on proliferation, migration and differentiation of neural stem cells in subventricular zone

目的探讨损伤嗅球对脑室下区（subventricular zone，SVZ）神经于细胞（neural stem cell，NSC）增殖、迁移及其在嗅球内分化的影响。方法健康雌性SD大鼠42只，采用完全随机数字表法分为正常对照组、等渗盐水组、嗅球损伤3d、1周、2周、3周、4周组，每组6只，嗅球内局部注射N－甲基－D－天冬氨酸（N－methyl－D－asparticacid，NMDA）制作嗅球损伤模型，以5－溴脱氧尿嘧啶（5－bromo－2－deoxyuridine，BrdU）标记NSC，免疫组化法观察嗅球损伤对SVZ区NSC增殖的影响。另取大鼠18只，采用完全随机数字表法分为正常对照组、等渗盐水组和嗅球损伤组，每组6只，于嗅球损伤后7d腹腔注射BrdU，4周后分别以免疫组化和荧光双标法观察SVZ区NSC迁移及其在嗅球内的分化情况。结果嗅球损伤后3d，SVZ区BrdU阳性细胞开始增高（26．33±2．58，P〈0．01），7d达高峰（35．33±3．01，P〈0．01），以后有所下降，但第4周仍有较高水平表达（19．50±2．26，P〉0．05）。嗅球损伤后5周，损伤组喙侧迁移流（rostral migratory－stream，RMS）及嗅球内的BrdU阳性细胞数（86．50±5．09，52．83±3．87）较正常对照组和等渗盐水组明显增多（P〈0．01），荧光双标示大部分BrdU阳性细胞同时表达神经元标志物神经元核抗体（neuronal nuclei antigen，Neun），少部分细胞表达星形胶质细胞标志物胶质纤维酸性蛋白（glial fibrillary acidic protein，GFAP）。结论损伤嗅球可促进SVZ区NSC增殖及其向嗅球迁移，新生细胞不但可以分化为神经元，也可分化为胶质细胞，并可能参与损伤后的修复作用。

Objective To detect the effect of olfactory bulb （OB） lesion on proliferation, migration and differentiation of the neural stem cells （NSCs） in the subventrieular zone （SVZ）. Methods Forty-two healthy female SD rats were enrolled and randomly divided into normal control group, isotonic saline group and OB lesion at day 3, at weeks 1, 2, 3 and 4 groups, six rats per group. OB lesion was induced by N-methyl-D-aspartie acid （NMDA） injection. Bromodeoxyuridine （BrdU） was injected intraperitoneally to label NSCs. Immunohistochemical staining was used to detect the proliferation of SVZ NSCs. In addition, another 18 rats were randomly divided into normal control group, isotonic saline group and lesion group, six rats per group. BrdU was injected intraperitoneally one week after OB lesion and then the animals were sacrificed four weeks after BrdU injection to detect the migration and differentiation of NSCs with immunohistochernistry and immunoflnoreseenee. Results Three days after OB lesion, BrdU-positive cells in SVZ began to increase （26.33 ±2.58, P 〈0. O1 ） , reached the maxinmm at week l （35.33 ± 3. O1 ,P 〈 0.01 ） and still sustained a high level at week 4 （ 19.50 ± 2.26, P 〉 O. 05 ）. Five weeks after the OB lesion, the rostral migratory-stream （RMS） and the BrdU-positive cells in OB were significantly increased （ 86.50 ± 5.09, P 〈 0.01 ） and （ 52.83 ±3.87,P 〈 0.01 ） , respectively. By using fluorescence double staining, most of the BrdU-positive cells were co-localized with the neuronal nuclear antigen （Neun）, with a portion of BrdU-positive cells expressing the glial fibrillary acidic protein （GFAP）. Conclusions OB lesion can improve the proliferation of NSCs in SVZ and migration of NSCs to OB. The newborn cells can differentiate into not only neurons, but also gliocytes and may be involved in lesion repair.