Minie Vanessa A, Petric Radmila, Ramos-Maciel Stephanie, Wright Emily C, Trainor Brian C, Duque-Wilckens Natalia
Department of Psychology, University of California Davis, CA 95616.
Department of Biology, University of North Carolina at Greensboro, Greensboro, NC, United States.
Appl Anim Behav Sci. 2021 Aug;241. doi: 10.1016/j.applanim.2021.105381. Epub 2021 Jun 29.
Domesticated mice and rats have shown to be powerful model systems for biomedical research, but there are cases in which the biology of species is a poor match for the hypotheses under study. The California mouse () has unique traits that make it an ideal model for studying biological mechanisms underlying human-relevant behaviors such as intra-female aggression, biparental care, and monogamy. Indeed, peer-reviewed scientific publications using California mouse as a model for behavioral research have more than doubled in the past decade. Critically, behavioral outcomes in captive animals can be profoundly affected by housing conditions, but there is very limited knowledge regarding species-specific housing needs in California mice. Currently, California mouse investigators have to rely on guidelines aimed for more common laboratory species that show vastly different physiology, behavior, and/or ecological niche. This not only could be suboptimal for animals' welfare, but also result in lack of standardization that could potentially compromise experimental reproducibility and replicability across laboratories. With the aim of assessing how different housing systems can affect California mouse behavior both in the home cage as well as the open field and social interaction tests before and after social defeat stress, here we tested three different caging systems: 1. Standard mouse cage, 2. Large cage, and 3. Large cage + environmental enrichment (EE), which focused on increasing vertical complexity based on observations that California mice are semiarboreal in the wild. We found that the effects of housing were largely sex specific: compared to standard cages, in females large + EE reduced home cage stereotypic-like backflipping and rearing behaviors, while large cage increased social interactions. In males, the large+EE cage reduced rearing and digging but did not significantly affect backflipping behavior. Interestingly, while there were no significant differences in the open field and social interaction pre-stress behaviors, large and large+EE housing increased the sensitivity of these tests to detect stress induced phenotypes in females. Together, these results suggest that increasing social and environmental complexity affects home cage behaviors in male and female California mice without interfering with, but rather increasing the magnitude of, the effects of defeat stress on the open field and social interaction tests.
家鼠和大鼠已被证明是生物医学研究的强大模型系统，但在某些情况下，物种生物学与所研究的假设并不匹配。加州小鼠（）具有独特的特征，使其成为研究与人类相关行为（如雌性间攻击、双亲照料和一夫一妻制）背后生物学机制的理想模型。事实上，在过去十年中，以加州小鼠为行为研究模型的同行评审科学出版物数量增加了一倍多。至关重要的是，圈养动物的行为结果会受到饲养条件的深刻影响，但关于加州小鼠特定物种的饲养需求的知识非常有限。目前，加州小鼠研究人员不得不依赖针对生理、行为和/或生态位差异很大的更常见实验室物种的指导方针。这不仅可能对动物福利不理想，还会导致缺乏标准化，这可能会损害跨实验室的实验可重复性和可复制性。为了评估不同的饲养系统如何在社交失败应激前后影响加州小鼠在笼内、旷场和社交互动测试中的行为，我们测试了三种不同的饲养系统：1. 标准小鼠笼，2. 大笼子，3. 大笼子 + 环境富集（EE），后者基于加州小鼠在野外半树栖的观察结果，侧重于增加垂直复杂性。我们发现饲养的影响在很大程度上具有性别特异性：与标准笼子相比，在雌性中，大笼子 + EE 减少了笼内刻板的后翻和竖毛行为，而大笼子增加了社交互动。在雄性中，大 + EE 笼子减少了竖毛和挖掘行为，但对后翻行为没有显著影响。有趣的是，虽然在应激前的旷场和社交互动行为上没有显著差异，但大笼子和大笼子 + EE 饲养增加了这些测试检测雌性应激诱导表型的敏感性。总之，这些结果表明，增加社交和环境复杂性会影响雄性和雌性加州小鼠的笼内行为，而不会干扰，反而会增加失败应激对旷场和社交互动测试的影响程度。
