在小鼠试验的气味辨别和习惯化
Summary
This manuscript describes a protocol to examine the olfactory system of rodents. The olfactory habituation/dishabituation test will allow investigators to determine whether a mouse habituates to a repeatedly presented odor and whether the mouse demonstrates dishabituation when presented a novel odor.
Abstract
This video demonstrates a technique to establish the presence of a normally functioning olfactory system in a mouse. The test helps determine whether the mouse can discriminate between non-social odors and social odors, whether the mouse habituates to a repeatedly presented odor, and whether the mouse demonstrates dishabituation when presented with a novel odor. Since many social behavior tests measure the experimental animal’s response to a familiar or novel mouse, false positives can be avoided by establishing that the animals can detect and discriminate between social odors. There are similar considerations in learning tests such as fear conditioning that use odor to create a novel environment or olfactory cues as an associative stimulus. Deficits in the olfactory system would impair the ability to distinguish between contexts and to form an association with an olfactory cue during fear conditioning.
In the odor habitation/dishabituation test, the mouse is repeatedly presented with several odors. Each odor is presented three times for two minutes. The investigator records the sniffing time directed towards the odor as the measurement of olfactory responsiveness. A typical mouse shows a decrease in response to the odor over repeated presentations (habituation). The experimenter then presents a novel odor that elicits increased sniffing towards the new odor (dishabituation). After repeated presentation of the novel odor the animal again shows habituation. This protocol involves the presentation of water, two or more non-social odors, and two social odors. In addition to reducing experimental confounds, this test can provide information on the function of the olfactory systems of new knockout, knock-in, and conditional knockout mouse lines.
Introduction
小鼠是依赖于嗅觉用于导航新环境，寻找食物，用于识别其它个人，和性行为1-3。重要的是，研究人员建立实验动物是否不管理涉及食品，社会交往，或意在引起从鼠标的响应任何气味行为测试前的嗅觉功能感。嗅觉缺失或无法不同的气味区分，可能会导致在各种行为范例误报或底片，所以其它类型的行为测试之前，执行一个鼠标的检测和辨别气味的能力应该建立。
嗅觉习惯/ dishabituation试验是在20世纪80年代4首先描述。测试已适应于由Drs小鼠使用。穆押嗯和杰奎琳·克劳利5。这是一种简单而廉价的测试，允许调查者ESTAblish一个鼠标可以检测和气味区分。除了测试嗅觉，该测试允许研究者观察小鼠的一般行为，应在测试方案的早期完成。关于鼠标的运动定性观察，焦虑的迹象，活动水平，并回应社会对气味的食物的气味可能预示着在测试可能进行的新领域。
在该试验中，浸入各种气味棉签呈现给小鼠三次在一排。与每个重复介绍的气味，将鼠标，观察者向棉棒，花费更少的时间与每个随后呈现调查它。当一个新的气味呈现，dishabituation发生，并且一个典型的鼠标会花费更多的时间来调查拭子，这表明它可在当前和以前的气味5区分。此测试被施用给一只小鼠在一时间，并包括45分钟ACClimation期间随后测试45分钟。
虽然这个测试很容易进行可能被用于调查有关鼠标的嗅觉系统的复杂问题。嗅觉的其他流行的测试，如掩埋食品测试，简单地建立嗅觉缺失的存在或不存在。然而，嗅觉辨别和习惯测试允许研究者确定鼠标不仅具有检测气味，但不同的气味之间可以区分的能力。习惯和dishabituation的格局已被用于建立新的突变体6,7气味区分。在一个令人惊讶的研究，Fadool及其同事利用气味的复杂混合物，表明小鼠基因靶向删除的Kv1.3通道都“的嗅觉超级”，可以区分非常相似的气味比正常老鼠更8。
当检查了新的基因敲除小鼠模型是有用的establis^ h的正常行为存在基本的感官任务。当早期的测试方案完成后，气味辨别和习惯测试给出了一个调查员有机会观察到任何异常行为。这些观察结果可以防止在随后的测试假阳性或阴性结果归因于混淆的突变体的特征。研究人员继续调查社会行为，需要验证基本的嗅觉功能变得越来越重要。除了检查嗅觉在突变系，这种测试可用于解决特定的问题，例如一个药物治疗是否特异性增加动物的响应社会刺激气味，或者如果它们的反应增大到所有刺激气味。
Protocol
Representative Results
Discussion
本文提供的结果是最优的小鼠。小鼠表现出一种新的气味了强烈的反响，然后迅速，观察者。之一，在该方法中的关键步骤是气味的制备。调查人员需要采取非常谨慎，以彼此隔离的气味，以防止污染。另一个重要方面是棉签的呈现。研究者需要解决的棉签的最佳位置，以便鼠标可以调查尖，但不撕裂的尖端。测试的一个重要组成部分是气味的选择。我们提出了三个非社会的气味，但它不会是很?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
This work is supported by a Baylor University Research Council grant and by a research grant from the Epilepsy Foundation.
Materials
| Mouse cage | Allentown | Standard mouse cage | |
| Wire lid | Allentown | BCU Mouse WBL 2500 | |
| Bedding | Harlan | 7090 Sani-Chips | |
| Cotton swabs | VWR | 89031-270 | 6” wooden handle |
| Banana extract | McCormick | ||
| Almond extract | McCormick | ||
| Laboratory tape | VWR | 89098-062 | |
| Stop watch | VWR | 62374-000 | |
| Nitrile gloves | VWR | 82026 | |
| Timing device | VWR | 61161-350 | |
| 15 mL conical tubes | VWR | 89003-294 | |
| 2 L beakers | Pyrex | 1003 | |
| Parafilm | Parafilm | PM-992 | 4” x 250’ |
| 1 L bottle with cap | VWR | 89000-240 |
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