Lack of Effect of Chlordiazepoxide on the Number of Falls in a Novel Falling‐Trap Test in Male C57BL / 6N Mice

Abstract

Behavioral tests in mice and other animals are widely used to study anxiety and to evaluate the efficacy of anxiolytic compounds. However, the validity of behavioral tests used to assess anxiety-like behavior has been questioned because their results are often inconsistent and not readily replicated across studies. We developed a simple falling-trap test to examine whether the number of falls could serve as an index of anxiety-like behavior. The test is designed to produce falls from an elevated path, based on the hypothesis that less-anxious mice would be more prone to fall. Male C57BL/6N mice were given vehicle or chlordiazepoxide (CDP), and their behavior was evaluated using both the novel test and the elevated plus maze (EPM). The outcomes were the number of falls in the falling-trap test and open-arm time in the EPM. In the falling-trap test, CDP-treated mice did not show a statistically significant increase in the number of falls compared with control mice. In contrast, CDP significantly increased open-arm time in the EPM. Thus, under the present experimental conditions, these findings did not support the hypothesis that the number of falls in the falling-trap test could serve as a measure of anxiety-like behavior. Further studies are needed to determine the conditions under which this assay could be useful and to establish its reliability and validity.