How to Improve and Refine the Elevated Plus Maze for Laboratory Mice

Abstract

peer reviewedThe daily light-dark cycles synchronize behavioural and physiological processes to the external environment. Light is the most important environmental cue that coordinates many aspects such as activity, maintenance behaviours, hormonal regulation or long-term potentiation. Mice are among the main animals used in behavioural neuroscience and preclinical research laboratories. Although nocturnal, they are generally tested during day (i.e. during their resting phase). Even if convenient for the experimenter, a perturbation of the sleep-wake cycle such as manipulations during day can generate some stress to the animal, produce few reliable data, contributing to reproducibility issue, and may lead to negative consequences for health, physiology, behaviour and cognition. Then the testing moment could be an important variable affecting animal behavior. It appears that rodents are less anxious during the dark phase, however, a lack of data regarding the effect the testing moment on behavior has recently been highlighted. Additionally, several studies evaluating the effects of the testing moment have shown conflicting results; these differences can be explained by various methodological aspects such as parameters related to the procedure but also by the way of collecting and interpreting behavioral data. In this study, we focused on an anxiety test. We tested 4 different testing moment to determine if there is a more appropriate testing moment where mice show the less anxiety. Previously, we have shown that the way of analyzing behavior can affect the results. Here, we refined our observation method to improve the data interpretation