miRNA-146a靶向干预改善晚期APP/PS1双转基因模型小鼠认知功能的实验研究

Experimental study on miRNA-146a targeted intervention in the improvement of cognitive function in late APP/PS1 double transgenic model mice

目的探讨miRNA-146a靶向干预对晚期APP/PS1(APPswe/PSEN1dE9)双转基因小鼠认知功能的改善作用。方法选用18月龄APP/PS1小鼠,分为AD组、干预组(ADI组)、同月龄C57小鼠(CON组),每组6只。ADI组小鼠给予miRNA-146a agomir 1 nmol,隔日鼻腔给药,AD组和CON组小鼠用DEPC(diethyl pyrocarbonate)代替,30 d后,采用Morris水迷宫、Y迷宫进行行为认知功能检测,免疫荧光和ELISA检测海马内Aβ含量的变化,同时采用Western Blotting检测海马内tau蛋白异常磷酸化的变化。结果ADI组小鼠的逃避潜伏期随着训练次数逐渐下降,与同龄AD组小鼠相比,第2、3、4、5天的逃避潜伏期明显缩短,在原平台所在象限停留时间及游泳路程百分比均明显增加(P<0.05或0.01)。在Y迷宫自发性交替反应实验中,ADI组小鼠在新异臂的停留时间、穿越新异臂的次数比同月龄AD组小鼠明显增加(P<0.05或0.01)。ADI组小鼠与AD组比较,海马区Aβ、Aβ42沉积斑数量显著降低,两组海马可溶性及不可溶性Aβ42含量的比较差异有统计学意义(P<0.05或0.01)。ADI组小鼠与AD组相比,海马组织中P-tau S396、P-tau T181和Ptau T205蛋白异常磷酸化水平明显减少(P<0.05或0.01)。结论miRNA-146a agomir靶向干预可改善晚期AD小鼠的行为和认知功能障碍,降低AD小鼠海马区Aβ/Aβ42蛋白的沉积及tau蛋白的异常磷酸化水平,缓解AD病理、生理进程。

Objective To investigate the effect of miRNA-146a targeted intervention in the improvement of cognitive function in late APP/PS1 double transgenic mice.Methods 18-month-old APP/PS1 mice were divided into the AD Group,intervention group(ADI Group)and the group of C57 mice with same month of age(CON Group),6 mice in each group.The ADI Group was given nasally administered with 1 nmol miRNA-146a agomir every other day,which was replaced with DEPC(Diethyl pyrocarbonate)for the AD and CON Group.After 30 days,Morris water maze(MWM)and Y-maze were used to detect behavioral cognitive function,immunofluorescence and ELISA were used to detect the changes of Aβcontent in hippocampus,and Western Blotting was used to detect the abnormal phosphorylation of tau protein in hippocampus.Results The ADI Group had the escape latency gradually reduced with the increase of training times,and had the escape latency on Day 2,3,4 and 5 significantly shortened and had the dwell time in the quadrant of the original platform and the percentage of swimming distance increased significantly compared with the Group AD at the same age(P<0.01).In Y-maze spontaneous alternating reaction experiment,the ADI Group had the dwell time in new arm and the number of crossing the new arm significantly higher than the AD Group at the same age(P<0.05 or 0.01).Compared with the AD Group,the ADI Group had the number of Aβand Aβ42 deposits in the hippocampus significantly decreased,and there was statistical difference in the content of soluble and insoluble Aβ42 in hippocampus between the two groups(P<0.05 or 0.01),and had the abnormal phosphorylation levels of P-tau S396,P-tau T181 and P-tau T205 in hippocampus significantly reduced(P<0.05 or 0.01).Conclusion The miRNA-146a agomir targeted intervention can improve the behavioral and cognitive dysfunction in late AD mice,significantly reduce the deposition of Aβ/Aβ42 protein and abnormal phosphorylation level of tau protein in hippocampus of AD mice,and alleviate the pathophysiological process of AD.