摘要：

目的 观察慢性应激对APP/PS-1 双转基因阿尔茨海默病（AD）小鼠认知功能和脑组织形态学的影响，探讨环境因素的作用机制。方法 采用Morris 水迷宫实验评价C57BL/6 小鼠（正常对照组，15 只）和APP/PS-1 双转基因小鼠［27 只，包括AD 组（13 只）和AD + 慢性不可预知性温和应激（CUMS）组（14 只）］空间学习和记忆能力，刚果红染色观察海马组织淀粉样蛋白沉积，透射电子显微镜观察海马CA1 区神经元超微结构。结果 与正常对照组相比，AD + CUMS 组小鼠Morris 水迷宫实验逃避潜伏期延长［（33.14 ± 14.37）s 对（21.22 ± 12.16）s；t = -2.701，P = 0.045］，平台象限停留时间缩短［（9.74 ± 1.35）s 对（15.02 ± 1.33）s；t = 2.639，P = 0.012］。与AD 组相比，AD + CUMS 组小鼠淀粉样斑块面积占海马面积百分比增加［（0.59 ± 0.03）%对（0.04 ± 0.03）%；t = -2.900，P = 0.005］。AD 组小鼠海马神经元超微结构轻度受损，表现为神经元胞膜尚完整，胞质基质尚均匀，细胞内出现脂褐素，胞核和核膜结构尚可，线粒体嵴膜融合，高尔基体部分模糊，内质网轻度扩张；AD + CUMS 组小鼠海马神经元超微结构受损明显，表现为胞膜部分模糊不清，胞质苍白，基质不均匀，各种细胞器数目均减少，细胞内可见较多脂褐素和自噬小体，胞核内染色质边集、核膜模糊，线粒体嵴膜融合严重，核糖体数目明显减少。结论 慢性不可预知性温和应激是阿尔茨海默病小鼠认知损害的诱发因素，可以加重海马神经元的病理改变。

关键词: 应激, 阿尔茨海默病, 认知障碍, 显微镜检查, 荧光, 显微镜检查, 电子, 透射, 疾病模型, 动物

Abstract:

Objective  To observe the effect of chronic unpredictable mild stress (CUMS) on the cognitive function and brain morphological changes in APP/PS-1 mice, one of the genetic mouse models of Alzheimer's disease (AD), and to investigate the possible role of environmental factors in genetic mouse model of AD. Methods  There were 22-week-old wild-type C57BL/6 male mice (control group, N = 15) and APP/PS-1 double transgenic male mice [N = 27: AD group (N = 13) and AD + CUMS group (N = 14)] tested in this study. Morris water maze test was used to evaluate spatial learning and memory of the mice. Amyloid deposition in the hippocampus was determined by Congo red staining. The ultrastructure of neurons in hippocampal CA1 region was observed by transmission electron microscope (TEM).  Results  Compared with control group, AD + CUMS group had significantly longer fifth-day escape latency [(33.14 ± 14.37) s vs (21.22 ± 12.16) s; t = -2.701, P = 0.045], and significantly shortened time spent in platform quadrant [(9.74±1.35) s vs (15.02 ± 1.33) s; t = 2.639, P = 0.012] in Morris water maze test. Compared with AD group, the percentage of amyloid plaque area in hippocampal area was increased in AD + CUMS group [(0.59 ± 0.03)% vs (0.04 ± 0.03)%; t = -2.900, P = 0.005]. The ultrastructure of hippocampal neurons in AD group was slightly damaged: cellular membrane was intact; cell matrix was uniform; intracelluar lipofuscin could be seen; the structure of nucleus and nuclear membrane had no obvious changes; mild fusion of cristae and membrane was seen in mitochondria; Golgi apparatus was partially indistinct; endoplasmic reticulum was mildly expanded. The ultrastructure of hippocampal neurons in AD + CUMS group was obviously damaged, including blurred cell membrane, reduced low-density and high-density granules in cytoplasm, uneven cell matrix, reduced number of organelles, lipofuscin and autophagosome deposition, obvious condensation of chromatin distributing over the fringe of nuclei, blurred nuclear membrane, serious fusion of mitochondrial cristae and membrane, and obviously decreased free ribosome in cytoplasm.  Conclusions  Chronic unpredictable mild stress plays an inducing role in cognitive impairment of AD mice, aggravating the pathological changes of hippocampal neurons.

Key words: Stress, Alzheimer disease, Cognition disorders, Microscopy, fluorescence, Microscopy, electron, transmission, Disease models, animal