University of Sunderland, Sunderland Pharmacy School, Wharncliffe Street, Sunderland SR1 3SD, UK.
Behav Brain Res. 2010 Mar 5;207(2):402-17. doi: 10.1016/j.bbr.2009.10.028. Epub 2009 Nov 10.
In the present report we describe the behavior of two albinos (BALB/c and CD-1) and one pigmented (c57/BL6) strains of mice exposed to a novel open space anxiety test in a single 12 min session. The test is based on exposure of mice to an unfamiliar elevated platform which is extended on two opposite sides with steep slopes presented downward or upward. In the first experiment, the behavior of mice was examined on the elevated platform at two different heights (75 and 100 cm) with downward slopes. In the second experiment, we examined the behavior of mice on the platform at the lowest height (75 cm) but with upward slopes which lead to a stand. In the third experiment, we examined the behavior of Balb/c mice on the platform at the lowest height (75 cm) with downward slopes, and a hub enclosure providing a protected space located in the centre of the platform. The least anxious strain of mice was expected to take risks and cross onto the slopes (experiments 1 and 3) and onto the stands (experiment 2). The results of experiment 1 show that Balb/c mice did not cross onto the slope, and CD-1 mice made more crossings into and spent more time on the slopes than c57 mice. The increase in the heights of the platform reduced the number of crossings on the platform in all three strains of mice, and decreased the time spent on the platform before first entry onto a slope in c57 and in CD-1 mice. It also decreased the number of entries and duration of entries onto the slopes in CD-1 mice. In experiment 2, Balb/c mice did cross onto the upward slopes but significantly less than c57 and CD-1 mice but they did not cross onto the stands attached to the end of the slopes. CD-1 mice made more entries onto and spent more time on the stands than c57 mice. In the third experiment, Balb/c and c57 mice spent most of their time inside a protective space (cylinder) placed in the centre of the platform demonstrating strong avoidance responses of the outer area of the platform, and only three c57 mice crossed onto the slopes for a very brief duration in one or two entries. In all three experiments, mice entered more frequently and spent more time in the outer areas than in the inner areas of the platform, particularly in the areas adjacent to slopes than in the areas adjacent to a void space. CD-1 mice appears the least anxious taking more risks by venturing onto the slopes and onto the stands while Balb/c appears the most anxious spending a large amount of time in the areas adjacent to the slopes. The different configurations of the test apparatus (experiments 1 and 2) seem to provide different incentives for the drive to explore and escape which may account for differences in anxiety responses whereas the presence of a protective space (experiment 3) appears to encourage avoidance responses.
在本报告中，我们描述了两种白化（BALB/c 和 CD-1）和一种色素沉着（c57/BL6）品系的小鼠在单次 12 分钟的实验中暴露于一种新的开放式焦虑测试中的行为。该测试基于将小鼠暴露于一个不熟悉的高架平台上，该平台的两个相对侧延伸出陡峭的斜坡，向下或向上倾斜。在第一个实验中，我们在两个不同的高度（75 和 100 cm）的高架平台上检查了小鼠的行为，斜坡向下。在第二个实验中，我们在最低高度（75 cm）的平台上检查了小鼠的行为，但斜坡向上，导致站立。在第三个实验中，我们检查了 Balb/c 小鼠在最低高度（75 cm）的平台上的行为，斜坡向下，以及在平台中心的保护空间的中心提供一个保护空间的中心。预期最不焦虑的品系的小鼠将冒险越过斜坡（实验 1 和 3）和站台（实验 2）。结果显示，实验 1 中的 Balb/c 小鼠没有越过斜坡，而 CD-1 小鼠比 c57 小鼠更多地进入和在斜坡上花费更多的时间。所有三种品系的小鼠的平台高度增加减少了在平台上的穿越次数，并减少了 c57 和 CD-1 小鼠首次进入斜坡前在平台上的时间。它还减少了 CD-1 小鼠进入和在斜坡上的时间。在实验 2 中，Balb/c 小鼠确实越过了向上的斜坡，但明显少于 c57 和 CD-1 小鼠，但它们没有越过斜坡末端的站台。CD-1 小鼠比 c57 小鼠更多地进入和在站台上花费更多的时间。在第三个实验中，Balb/c 和 c57 小鼠大部分时间都在平台中心放置的一个保护空间（圆柱体）内，表现出对平台外部区域的强烈回避反应，只有三只 c57 小鼠在一两个进入中短暂地越过了斜坡。在所有三个实验中，小鼠比平台的内区更频繁地进入并花费更多的时间在外区，特别是在与斜坡相邻的区域比在与空旷空间相邻的区域。CD-1 小鼠似乎最不焦虑，冒险进入斜坡和站台，而 Balb/c 小鼠似乎最焦虑，在与斜坡相邻的区域花费大量时间。测试设备的不同配置（实验 1 和 2）似乎为探索和逃避的驱动力提供了不同的激励，这可能解释了焦虑反应的差异，而保护空间的存在（实验 3）似乎鼓励了回避反应。
