Notch1介导有氧运动改善阿尔茨海默症小鼠海马超微结构与空间记忆能力

关键词：阿尔茨海默症  有氧运动  Notch1  学习记忆

Keywords:Alzheimer's disease  aerobic exercise  Notch1  learning and memory

摘要：

      摘要 目的：观察DAPT抑制Notch1后，有氧运动对阿尔茨海默症（Alzheimer's disease， AD）小鼠海马组织病理学的改变，探究有氧运动能否通过Notch1改善AD小鼠的病理学特征及学习记忆能力。 方法：将3月龄APP/PS1双转基因AD小鼠随机分为4组：对照组（ADV）、运动对照组（ADV+E）、Notch1抑制组（ADD）和运动中Notch1抑制组（ADD+E），每组20只。对照组自然喂养，运动组进行有氧运动干预，自然喂养或运动干预均为20周。在第18周注射溶剂或Notch1抑制剂，第19周进行为期1周的Morris水迷宫实验，第20周进行为期1周的八臂迷宫实验，评估小鼠的学习记忆能力。随后取脑组织，采用电镜技术检测神经元及其突触损伤等病理变化，采用实时PCR、免疫荧光及Western Blot技术分别检测Aβ沉积及Notch1表达。 结果：在MWM水迷宫实验的过程中，ADV+E组的表现显著优于ADV组小鼠（P<0.05），ADD+E组与ADD组小鼠表现没有显著差异，ADD组与ADV组小鼠表现没有显著差异，ADV+E组的表现显著优于ADD+E组小鼠（P<0.05）。在八臂迷宫的最终测试实验中，ADV+E组的表现显著优于ADV组小鼠（P<0.05），ADD+E组与ADD组小鼠表现没有显著差异，ADD组与ADV组小鼠表现没有显著差异，ADV+E组的表现优于ADD+E组小鼠（P<0.05）。通过电镜发现，与ADV组相比，ADV+E组突触的数量显著增加，其PSD厚度相较于ADV组也有显著增加（P<0.05）；ADD+E组与ADD组之间在突触的数量、PSD厚度及突触间隙之间的距离没有显著差异；ADD组与ADV组之间在突触的数量、PSD厚度及突触间隙之间的距离没有显著差异；与ADV+E组相比，ADD+E组突触的数量显著降低，其PSD厚度相较于ADV组也有显著降低（P<0.05）。通过实时PCR、免疫荧光及Western Blot研究发现与ADV组小鼠相比，ADD组小鼠海马DG区Notch1的表达显著降低（P<0.05），Aβ1-42没有显著差异；ADV+E组小鼠海马DG区Aβ1-42、Notch1表达显著低于ADV组（P<0.05）；ADD+E组小鼠海马DG区Aβ1-42、Notch1的表达与ADD组相比没有显著差异。 结论：抑制Notch1会抑制运动对AD小鼠病程及学习记忆能力的改善作用。因此，Notch1可能是运动改善AD小鼠的病理学特征及学习记忆能力的重要影响因子。

Abstract:

      Abstract Objective： To observe the changes of aerobic exercise on hippocampal histopathology of AD mice after inhibiting Notch1 signaling pathway by DAPT， and explore whether aerobic exercise can improve the pathological characteristics and learning and memory ability of AD mice through Notch1. Method： Three months old APP/PS1 double transgenic AD mice were randomly divided into four groups： control group（ADV）， exercise control group（ADV+E）， Notch1 inhibition group （ADD） and exercise Notch1 inhibition group（ADD+E），20 mice in each group. The control group did not receive exercise intervention， while the exercise group received aerobic exercise intervention. Natural feeding or exercise intervention lasted for 20 weeks. solvent or Notch1 inhibitors were injected at 18 weeks. To assess the learning and memory abilities,Morris Water Maze（MWM） was tested at 19 weeks， and eight-arm maze was tested at 20 weeks. Subsequently，brain tissue was taken and pathological changes were detected by electron microscopy. Real time PCR，immunofluorescence and Western Blot were used to detect Aβ deposition and Notch1 expression，respectively. Result： In the MWM testing， the ADV+E group had better performance than that the ADV group （P<0.05）， there was no significant difference between ADD+E group and ADD group，as well as between ADD group and ADV group， and the performance of ADV+E group was better than that of the ADD+E group （P<0.05）. In the 8 arm maze testing， the performance of ADV+E group was better than that of the ADV group （P<0.05）， and there was no significant difference between ADD+E group and ADD group， as well as between ADD group and ADV group， and the performance of ADV+E group was better than that of the ADD+E group （P<0.05）. The results of electron microscopy showed that the mitochondrial morphology of mice in ADV+E group was significantly better than that of the mice in AD group （P<0.05）. Compared with the ADV group， the number of synapses and the PSD thickness were significantly increased（P<0.05）. There were no significant differences in the number of synapses， the thickness of PSD and the distance between synaptic gaps between ADD+E group and ADD group, as well as between ADD group and ADV group. Compared with the ADV+E group， the number of synapses in the ADD+E group was significantly decreased， and the PSD thickness in the ADD+E group was also significantly decreased compared with the ADV group （P<0.05）. The results of real time PCR， immunofluorescence and Western blot showed that compared with the ADV group， the expression of Notch1 in the ADD group was significantly decreased （P<0.05）， while the expression of Aβ1-42 showed no significant difference. The expressions of Aβ1-42 and Notch1 in the ADV+E group were significantly lower than those in the ADV group（P<0.05）. The hippocampal expressions of Aβ1-42 and Notch1 in the ADD+E group had no significant differences with those in the ADD group. Conclusion： Inhibiting the expression of Notch1 perhaps can inhibit the exercise-induced improvement of the disease course and learning and memory ability of AD mice. Therefore， Notch1 signaling pathway may be an important factor in the exercise-induced improvement of pathological characteristics and learning and memory ability of AD mice.