Environmental enrichment (EE) has been a widely used tool to improve animal welfare, as well as to study brain plasticity. Traditional EE settings in the field of neuroscience employ highly complex cages with numerous objects and increased space, whereas more simple additions included for the control treatment are rarely considered in the experimental design. This leads to a lack of consistency of what neuroscientists designate as "standard housing," which might compromise the reproducibility of the results. Therefore, we employed standard-sized cages to study how different EE configurations can affect several biological markers of animal welfare. We first compared barren cages with cages containing nest material and a cardboard roll or cages having a complex set of elements. For this purpose, we studied anxiety-like behavior, corticosterone metabolites in feces, and cell survival in the hippocampus. Complex enrichment (CE) increased the concentration of corticosterone metabolites while also decreasing anxiety-like behavior. Interestingly, both simple and CEs were able to promote cell survival in the hippocampus, and this measure was positively correlated to corticosterone metabolites. Furthermore, in a second experiment, one of the elements of the CE was able to reduce anxiety-like behavior and blood glucose reactivity after exposure to a stressful situation. Altogether, this study calls attention about how sensitive experimental outcomes are to these simple EE elements. Even though EE is recommended by most guidelines for the care and use of laboratory animals, a detailed analysis of the EE protocol that is going to be implemented is highly encouraged. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

中文翻译：

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添加到标准尺寸笼子中的简单和复杂的富集对雌性瑞士小鼠（Mus musculus）的行为、生理和神经变量的影响。

环境富集 (EE) 已被广泛用于改善动物福利以及研究大脑可塑性。神经科学领域的传统 EE 设置采用高度复杂的笼子，其中包含大量物体和更大的空间，而在实验设计中很少考虑包含用于控制处理的更简单的添加物。这导致神经科学家称为“标准住房”的内容缺乏一致性，这可能会影响结果的可重复性。因此，我们采用标准尺寸的笼子来研究不同的 EE 配置如何影响动物福利的几种生物标志物。我们首先将贫瘠的笼子与包含巢材料的笼子和纸板卷或具有一组复杂元素的笼子进行了比较。为此，我们研究了类似焦虑的行为，粪便中的皮质酮代谢物和海马体中的细胞存活率。复合物富集 (CE) 增加了皮质酮代谢物的浓度，同时也减少了焦虑样行为。有趣的是，simple 和 CEs 都能够促进海马中的细胞存活，并且这种测量与皮质酮代谢物呈正相关。此外，在第二个实验中，CE 的一个要素能够减少暴露于压力情况后的焦虑样行为和血糖反应。总而言之，这项研究引起了人们对实验结果对这些简单 EE 元素的敏感程度的关注。尽管大多数关于实验室动物护理和使用的指南都推荐使用 EE，但强烈鼓励对将要实施的 EE 协议进行详细分析。