小鼠缺血再灌注损伤后海马齿状回Wnt1、Wnt3a的表达变化

The changes of Wnt1,Wnt3a expressions in hippocampus of mice suffering ischemic reperfusion injury

目的探讨Wnt/β-catenin相关因子在缺血再灌注小鼠海马中的表达变化。方法将80只1月龄健康雄性昆明小鼠随机分为正常组、假手术组、缺血再灌注1、3、7、14、21、28 d组,通过夹闭小鼠双侧颈总动脉0.5 h再通的方法建立小鼠脑缺血再灌注损伤模型,采用腹腔注射5-溴脱氧尿嘧啶核甘(BrdU)检测海马齿状回区神经干细胞(NSCs)增殖规律及通过原位杂交法和免疫组织化学染色方法检测Wnt/β-catenin信号通路重要信号分子Wnt1、Wnt3a的表达变化。结果 BrdU检测显示正常组和假手术组小鼠海马齿状回区可见少量BrdU阳性细胞,缺血再灌注后3 d BrdU阳性细胞开始增高(P<0.01),缺血再灌注后7 d达高峰(P<0.01),随着灌注时间的延长呈下降趋势,缺血再灌注后28 d,BrdU阳性细胞数降至正常水平(P>0.05)。原位杂交法结果显示正常组、假手术组海马齿状回颗粒细胞下层均无明显Wnt1、Wnt3a阳性表达。缺血再灌注各组均可见Wnt1、Wnt3a阳性细胞,再灌注后1 d表达开始增加,14 d达高峰,28 d减少至正常水平。与正常组和假手术组比较,缺血再灌注各组Wnt1、Wnt3a阳性细胞数明显增多(P<0.05)。结论小鼠脑缺血再灌注损伤可激发内源性NSCs的增殖。当Wnt/β-catenin途径被激活时,Wnt1、Wnt3a在海马齿状回颗粒细胞下层的表达,为进一步研究Wnt信号通路在脑缺血再灌注损伤中的作用及其机制奠定了基础。

Objective To observe changes of Wnt/β-catenin related factors in hippocampus of mice suffering ischemic reperfusion injury（IRI）. Methods 80 one-month age, healthy Kunming mice, male, were divided into normal control group, Mock group and isehe- mic reperfusion groups （further divided into 1st, 3rd, 7th, 14th, 21st, 28th day groups）. IRI model was established by clamping carotid ar- teries in both sides for half an hour and then removing the clamp. Proliferation profile of neural stem cells （NSCs） in dentate gyrus region was explored by intraperitoneal injection of BrdU and expression changes of Wntl and Wnt3a molecules in Wnt/β-catenin signaling pathway were investigated with in situ hybridization and immunohistochemical staining method. Results Few BrdU positive cells were observed in dentate gyrus region from normal control and Mock group mice. The amount of BrdU positive cells started to increase from the 3rd day in IR1 group and peaked on the 7th day（P 〈0. 01 ） ,and then decreased. The amount of BrdU positive cells on 28th day was reduced to normal level （P 〉 0. 05）. In situ hybridization results showed no obvious expression of Wntl and Wnt3a in basolateral layer of particulate cells from nor- mal control and Mock groups. Wntl and Wnt3a positive cells were observed in 1RI group. The expression level increased the second day after repel-fusion and peaked on the 14th day, on day 28, the expression returned to normal level. Compared with normal control and Mock groups, Wntl and Wnt3a positive cells in ischemic reperfusion group increased significantly and the differences were significant（ P 〈 0. 05 ）. Conclusions IRI could lead to proliferation of endogenous NSCs. Once Wnt/13-catenin pathway is activated, the expression of Wntl and Wnt3a in basolateral layer of particulate cells from dentate gyrus region are increased which lays foundation h^r further study of W＇nt pathway＇s effects in the process of IRI.