Morris水迷宫实验：优化小鼠品系和测试环境
Summary
This manuscript describes a Morris water maze (MWM) protocol tailored for use with a commonly used mouse model of Alzheimer’s disease. The MWM is widely used in transgenic mouse models. Implementation of a procedure sensitive to the background strain of the mouse model is essential for detecting group differences.
Abstract
The Morris water maze (MWM) is a commonly used task to assess hippocampal-dependent spatial learning and memory in transgenic mouse models of disease, including neurocognitive disorders such as Alzheimer’s disease. However, the background strain of the mouse model used can have a substantial effect on the observed behavioral phenotype, with some strains exhibiting superior learning ability relative to others. To ensure differences between transgene negative and transgene positive mice can be detected, identification of a training procedure sensitive to the background strain is essential. Failure to tailor the MWM protocol to the background strain of the mouse model may lead to under- or over- training, thereby masking group differences in probe trials. Here, a MWM protocol tailored for use with the F1 FVB/N x 129S6 background is described. This is a frequently used background strain to study the age-dependent effects of mutant P301L tau (rTg(TauP301L)4510 mice) on the memory deficits associated with Alzheimer’s disease. Also described is a strategy to re-optimize, as dictated by the particular testing environment utilized.
Introduction
转基因小鼠模型已经有助于评估阿尔茨海默氏病（AD）的病理生理学，以及治疗性干预的潜在。认知任务，如在Morris水迷宫（MWM），通常使用与这些模型，以确定的记忆障碍的分子相关因素，并评估临床前药物的疗效。这是至关重要的，但是，认知任务的动态范围足够宽，以检测细微的治疗效果。与AD小鼠模型，认知缺陷通常是年龄依赖性，小鼠显示性能逐步下降（ 例如 ，1）。利用一个敏感的认知任务的可允许检测细微的差别较早在动物的寿命，从而减少与衰老动物相关的成本。例如，减少的海马依赖性巴恩斯训练试验的数目从15到5迷宫增加了工作的难度，造成对d在3xTg模型赤字在较早的年龄比以前etection报道2。早期发现的赤字不仅提供了大量的时间和成本节约，这也增加了可能性，潜在的认知缺陷的分子变化可以被识别。
影响的认知任务的灵敏度的一个因素是小鼠模型的遗传背景应变。例如，BALB / c小鼠相比其他菌株，如C57BL / 6 3表现出优异的性能在学习和记忆任务。 F1的FVB /的N×129S6背景用于两个AD的最广泛的机型，和的Tg2576 RTG（TauP301L）4510款。该菌株表现出MWM相对于其他菌株，包括B6 / SJL小鼠4出众的学习能力。正因为如此出众的学习能力，经过大量的训练使用单一探头可以掩盖从过度训练造成的组间差异。此外，sensitivit探测试验y可以为年龄依赖性。之前我们已经表明，较早的探测试验，经过有限的隐藏平台的训练，都是在年轻的Tg2576的差异相比，比年轻的转基因阴性对照同窝更敏感更广泛的培训后，5探头插入试验。相比之下，经过广泛的培训探测试验是中老年（20-25个月）相比老同窝Tg2576小鼠更敏感比更早的探测试验5。由散布探针试验在整个训练，可能是一个敏感的试验将确定增加，尤其是当纵向测试被执行并且一个特定的探针试验的灵敏度是年龄依赖性的。 图1示出的F1 FVB / N x的性能优越对于这株优化协议下129S6小鼠相比B6 / SJL背景下的协议一起训练更广泛的培训小鼠。
该MWM是一般认为，以提供可靠的措施，是在这两个时间和实验室6再现的。例如，主协议最初由美国明尼苏达我们的实验室1,7已成功地与西弗吉尼亚大学8细微的修改来实现。同样，减值相当于水平RTG（TauP301L）的变化相对4510小鼠，如果安置无病原体或常规条件下，9至对照同窝。然而，该测试环境可以影响MWM任务的灵敏度。因素，例如室内照明，排风口，温度梯度和噪声都有助于环境线索4可最终影响性能。当我们的明尼苏达实验室和动物饲养被移动到一个新的建筑物，最多在野生型性能降低38％，观察，基本上减少了任务和检测转基因相关的缺陷的能力的动态范围。这种变化在PErformance发生尽管设计测试室是等价的尺寸和配置的，并使用相同的施加的视觉线索。 A“重新优化”的原始协议被要求增加新的测试环境的MWM任务的动态范围。
这里专为与F1 FVB / N利用原有协议x 129S6背景5描述。因为一些研究表明应力差MWM性能10和预处理相关的所用性能11减轻这种应力诱发赤字，预处理协议被设计为适应小鼠到池之前MWM测试的引入和除去。以下预处理，小鼠经历可见平台训练，其中一个凸起的平台上都标有一个标志。可见平台训练来识别小鼠与涉及感觉异常性能问题。用在描述PROT排除标准ocol部分，性能不称职的小鼠从隐藏的培训平台和探测试验的后续检查中删除。在隐藏平台的训练和探头试验损伤被解释为认知缺陷，因为感觉性能分解出来的数据。可见平台的培训结束后，老鼠开始隐藏平台的训练，其中该平台浸没在水中，并保持在相对位置外部线索相同。在该平台被除去（探针试验）试验是在散布在整个隐藏平台训练以评估额外训练的影响。因为探针的试验发生在每一天的开始，前附加隐蔽平台训练，探针试验测量动物记住以下一个20小时的延迟平台的位置的能力，考虑参考存储器12的量度。最后，方法，使这个原始协议被重新优化时的变化在测试环境打乱了控制性能描述。
Protocol
Representative Results
Discussion
在MWM任务被广泛用于评估空间学习和记忆。然而，这个任务的鲁棒性可受许多因素的影响，并需要优化为背景应变和测试环境。如在图4中，相同的训练协议和应用在两个不同的检测室（相当于大小和布局）使用视觉提示产生显著不同的探针性能。由于检测室的许多特征可能有助于空间线索4，据推测，这两个房间中的一些这使测试更困难未知的方式显著不同。在修改的额外迷?…
Declarações
The authors have nothing to disclose.
Acknowledgements
这项工作是支持普通医学科学研究所（里德/恩格勒-Chiurazzi – U54GM104942），国立神经疾病和中风（阿什 – R01NS33249，R01NS63249和R01NS79374），铜业（恩格勒-Chiurazzi – P20GM109098）时，阿尔茨海默氏症协会（里德 – NIRG-12-242187），西弗吉尼亚大学一个研究学部参议院拨款（里德），一个WVU PSCOR补助金（里德），以及内部资金从医学教务处的西弗吉尼亚大学学院（恩格勒-Chiurazzi）。内容完全是作者的责任，并不一定代表美国国立卫生研究院或阿尔茨海默氏症协会的官方意见。
Materials
| Viewer Tracking software | Biobserve | This particular software is not a requirement – there are other tracking systems available | |
| Pre-handling pool | Dimensions approximately 1 foot wide x 2 feet long x 1.5 feet deep | ||
| Plastic beaker | 1 liter | ||
| Scoop | |||
| Small net | |||
| Stopwatch | |||
| White circular tub | |||
| Non-toxic white tempera paint | Any color can paint can be used; must completely cover the hidden platform | ||
| Platform | Color should contrast that of maze | ||
| Curtain rod | |||
| Curtains | |||
| Mouse performance tracking software | |||
| Circular tub | Uusally white in color; approximately 4 feet in diamater | ||
| Platform | Painted same color as the water |
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