嗅球损伤对成年大鼠脑室下区神经干细胞增殖和NMDA受体亚单位2B表达的影响

Effects of olfactory bulb lesion on neural stem cells proliferation and expression of NMDA-receptor subunit 2B in the subventricular zone of rats

目的 研究嗅球损伤对成年大鼠脑室下区（SVZ）神经干细胞增殖和NMDA受体亚单位2B表达的影响.方法 正常成年雌性SD大鼠60只,随机分成正常对照组、生理盐水组、嗅球损伤组,嗅球内局部注射N-甲基-D-天冬氨酸（N-methyl-D-aspartic acid,NMDA）制作嗅球损伤模型,术后分3d、7d、14 d、28 d四个时间点取脑.行免疫组织化学染色观察神经干细胞（Nestin）、增殖细胞（Ki67）及NMDA受体亚单位NR2B阳性细胞数.结果 （1）各组大鼠SVZ均可见Nestin阳性细胞,嗅球损伤后7 d Nestin IOD值增加[（29601±1788）/0.01 mm2,P＜0.05],14 d达到高峰[（31400±3435）/0.01 mm2,P＜0.05],28 d后有所下降[（27600±3209）/0.01 mm2,P＜0.05].（2）各组大鼠SVZ均表达Ki67阳性细胞,嗅球损伤后7d、14 d和28 d SVZ Ki67阳性细胞数分别为[（28.60±2.41）/0.01 mm2]、[（34.00±2.55）/0.01 mm2]、[（30.40±1.14）/0.01 mm2],显著高于正常组和生理盐水组阳性细胞数（P＜0.05）.（3）各组大鼠SVZ均表达NR2B阳性细胞,嗅球损伤3d,NR2B阳性细胞数开始增加[（58.80±2.95）个/0.01 mm2,P＜0.05],14 d达到高峰[（68.40±4.04）个/0.01 mm2,P＜0.05],28 d阳性细胞数有所下降,但维持较高的水平[（62.20±3.56）个/0.01 mm2,P＜0.05].（4）嗅球损伤后不同时间点NR2B阳性细胞数与Ki67阳性细胞数有高度正相关性,r=0.968,P＜0.05.结论 （1）嗅球损伤能刺激成年大鼠SVZ神经干细胞的增殖;（2）嗅球损伤后NDMA受体亚单位NR2B表达增加,并且与神经干细胞的表达变化趋于一致,因此推断NR2B可能参与SVZ神经干细胞的增殖过程.

Objective To investigate the effects of olfactory bulb（OB） lesion on neural stem cells proliferation and expression of NMDA receptor subunit 2B in subventricular zone（SVZ） of rats.Methods Sixty adult female SD rats were randomly divided into normal group,saline group and OB lesion group.OB lesion was induced by N-methyl-D-aspartic acid （NMDA） injection.Each group was respectively divided into four time points including 3 d,7 d,14 d and 28 d.Immunohistochemistry staining was used to detect the number of Nestin,Ki67 and NR2B-positive cells in the SVZ.Results （1） Nestin positive cells in the SVZ were shown at the different time of three groups.Seven days after OB lesion,IOD value of nestin-positive cells began to increase（（29601± 1788）/0.01 mm2,P〈0.05）,reached the maximum at 14 d（（49800±3701）/0.01 mm2,P〈0.05） and still sustained a high level at 28 day（（27600±3209）/0.01 mm2,P〈0.05）.（2）Ki67 positive cells in the SVZ were shown at the different time of three groups.The number of Ki67-positive cells was increased significantly at 7 d,14 d and 28 d after OB lesion compared to normal group and saline group （P〈0.05）.（3）NR2B immune expression in the SVZ was shown at the different time of three groups.The NR2B-positive cells increased at 3 d after OB lesion（58.80±2.95,P〈0.05）,reached the maximum at 14 d（68.40±4.04,P〈0.05）.At 28 d of OB lesion,the number of positive cells was reduced,but still sustained a high level（62.20±3.56,P〈0.05）.（4）The positive cells of NR2B and Ki67 were highly positive correlation at different time after OB lesion（r=0.968,P〈0.05）.Conclusions OB lesion can stimulate neural stem cell proliferation and increases the expression of NR2B.The increased mode of NR2B is in accordance with the schedule of the neural stem cells increase induced by OB lesion.Therefore,it indicates that the NMDA receptor subunit 2B may be involved in neural stem cell proliferation.