3xTg-AD转基因小鼠抑郁模型的建立及认知相关病理改变与比较

Establishment of depression model in 3xTg-AD transgenic mice and comparison of cognitive-related pathological changes

目的:为分析抑郁状态对阿尔茨海默病(AD)小鼠病理变化的影响,对3xTg-AD小鼠进行慢性社交挫败应激(CSDS)与慢性温和不可预知性应激(CUMS)刺激,建立早期AD诱发抑郁小鼠模型,并检测小鼠认知行为改变、海马区小胶质细胞的活化及神经元的丢失情况。方法:3xTg-AD小鼠3月龄时交替进行为期8 d的应激刺激,通过行为学评估小鼠抑郁状态并制订评价标准,进行认知行为的检测及分析,取海马部位脑组织切片进行免疫荧光染色,观察β-淀粉样蛋白(Aβ)沉积和微管相关蛋白(tau)的聚集情况、小胶质细胞活化及神经元的丢失情况。结果:抑郁相关行为学结果提示CSDS+CUMS组小鼠出现抑郁相关表型。认知行为检测发现CSDS+CUMS组小鼠的新物体识别指数明显降低(P<0.05),Morris水迷宫显示CSDS+CUMS组的空间记忆能力显著降低(P<0.05),但条件恐惧实验中CSDS+CUMS组小鼠无明显恐惧记忆丧失。免疫荧光染色结果显示CSDS+CUMS组小鼠海马区4月龄出现Aβ沉积,小胶质细胞的活化增加(P<0.001),并出现一定程度的神经元丢失(P<0.001);8月龄时CSDS+CUMS组小鼠提早出现tau蛋白聚集。结论:我们建立了一种AD诱发抑郁小鼠模型,3xTg-AD小鼠抑郁后提早出现学习记忆能力下降,海马区神经元AD相关病理沉积增多,并伴随小胶质细胞活化及神经元丢失。

Objective:To analyze the effect of depressive state on Alzheimer’s disease(AD)mice,3xTg-AD mice were stimulated with chronic social frustration stress(CSDS)and chronic mild unpredictable stress(CUMS),to establish an early AD-induced depression mouse model,and to detect cognitive and behavioral changes,activation of microglia in the hippocampus and neuronal loss.Methods:Three-month-old mice were subjected to 8-day stress stimulation alternately,the depressive state of the mice was evaluated by behavior,the evaluation criteria were formulated,and the cognitive behavior was detected and analyzed,and the hippocampal brain tissue sections were stained with immunofluorescence to observe the deposition ofβ-amyloid(Aβ)and the aggregation of microtubule-associated protein(tau),microglia activation and neuronal loss.Results:Depression-related behavioral results showed that the CSDS+CUMS group had depression-related phenotypes.Cognitive-behavioral testing showed that the new object recognition index of the mice in the CSDS+CUMS group was significantly reduced(P<0.05),and the Morris water maze showed that the spatial memory ability of the CSDS+CUMS group was significantly reduced(P<0.05),but there was no obvious fear memory loss in the CSDS+CUMS group in the conditioned fear experiment.The results of immunofluorescence staining showed that Aβdeposition appeared in the hippocampus at 4 months of age,the activated microglia increased(P<0.001),and a certain degree of neuronal loss appeared in the CSDS+CUMS group(P<0.001);At 8 months of age,the CSDS+CUMS group showed tau protein aggregation early.Conclusion:We established a model of AD-induced depression in AD mice,in which 3xTg-AD mice experienced early decline in learning memory and increased AD-related pathological deposition of neurons in the hippocampus,accompanied by microglial activation and neuronal loss.