水通道蛋白4基因敲除对老年小鼠行为和脑形态变化的影响

摘要

Objective:To investigate the effects of aquaporin-4 (AQP4) gene knockout on the behavior changes and cerebral morphology during aging in mice,and to compare that of young and aged mice between AQP4 knockout mice (AQP4-/-) and wild type mice (AQP4 +/+).Methods:Fifty-eight CD-1 mice were divided into four groups:young (2-3 months old) AQP4-/-,aged (17-19 months old)AQP4-/-,young AQP4 +/+ and aged AQP4 +/+.The activity levels and exploring behavior of mice were tested in open field.The neurons were stained with toluidine blue and NeuN,the astrocytes and microglias were stained with GFAP and Iba-1,respectively.The morphological changes of neuron,astrocyte and microglia were then analyzed.Results:Compared with young mice,the total walking distance in open field of aged AQP4 +/+ mice and aged AQP4-/-mice decreased 41.2％ and 44.1％,respectively (P ＜0.05) ; while there was no difference in the ratio of distance and retention time in the central area of open field.The density of neuron in cortex of aged AQP4 +/+ mice and aged AQP4-/-mice decreased 19.6％ and 15.8％,respectively (P ＜0.05),while there was no difference in the thickness of neuron cell body in hippocampus CA1 region.The density of astrocyte in hippocampus CA3 region of aged AQP4 +/+ mice and aged AQP4-/-mice increased 57.7％ and 64.3％,respectively (P ＜ 0.001),while there was no difference in the area of astrocyte.The area of microglia in hippocampus CA3 region of aged AQP4 +/+ mice and aged AQP4-/-mice increased 46.9％ and 52.0％,respectively (P ＜ 0.01),while there was no difference in the density of microglia.Compared with AQP4 +/+ mice,the young and aged AQP4-/-mice showed smaller area of astrocyte in hippocampus CA3 region,reduced 18.0％ in young mice and 23.6％ in aged mice.There was no difference between AQP4+/+ mice and AQP4-/-mice for other observed indexes.Conclusions:AQP4 may be involved in change of astrocyte and astrocyte-related behaviors during aging.AQP4 gene knockout may have limited effects on the change of neuron,microglia and most neuronal behaviors in aging process.%目的:观察AQP4基因敲除(AQP4-/-)对老年小鼠行为学和脑形态学变化的影响,揭示AQP4在脑老化中的作用.方法:58只CD-1小鼠按基因型与月龄分为4组:年轻(2～3个月龄)AQP4-/-组、老年(17 ～ 19个月龄)AQP4-/-组、年轻AQP4+/+组和老年AQP4+/+组.采用开场试验测定小鼠运动量和探究行为,脑切片进行神经元特异性染色(甲苯胺蓝染色、NeuN染色)、星形胶质细胞特异性染色(GFAP染色)和小胶质细胞特异性染色(Iba-1染色),观察并计数皮层和海马神经元、星形胶质细胞、小胶质细胞的形态和数量.结果:与年轻小鼠比较,老年AQP4+/+和AQP4-/-小鼠在开场试验的总活动距离分别减少41.2％和44.1％ (P ＜0.05),各组小鼠在中心区域的活动距离和滞留时间无差异；老年AQP4+/+和AQP4-/-小鼠皮层神经元密度分别降低19.6％和15.8％ (P ＜0.05),各组间CA1区神经元胞体层厚度无差异；老年AQP4+/+和AQP4-/-小鼠海马CA3区星形胶质细胞密度分别增加57.7％和64.3％ (P ＜0.001),各组间星形胶质细胞的总面积无显著差异；老年AQP4+/+和AQP4-/-小鼠海马CA3区小胶质细胞的面积分别增加46.9％和52.0％ (P ＜0.01),各组间小胶质细胞密度无显著变化.与AQP4+/+小鼠相比,AQP4-/-小鼠在海马CA3区星形胶质细胞总面积明显减小,年轻小鼠减小18.0％ (P ＜0.01),老年小鼠减小23.6％(P＜0.01),其余指标均无显著差异.结论:AQP4可能影响小鼠星形胶质细胞形态及与星形胶质细胞相关的神经功能,对神经元、小胶质细胞的形态和部分相关神经行为无明显影响,AQP4基因敲除对小鼠脑老化过程发生的脑形态和神经行为变化无显著影响.