Marble burying as a test of the delayed anxiogenic effects of acute immobilisation stress in mice.

A majority of rodent studies characterizing the anxiogenic effects of stress have utilized exploration-based models, such as the elevated plus-maze. An alternative strategy has relied on ethologically natural behavior such as defensive burying. One such paradigm, marble burying, has proven to be an effective behavioral assay of the anxiolytic effects of pharmacological manipulations, and of genetically modified mouse models. Relatively little, however, is known about the sensitivity of this test in assessing the anxiogenic effects of stress. Most of the earlier reports have examined the immediate, but not more long-term, effects of pharmacological or environmental manipulations in mice. Hence, we used the marble burying test to examine if acute immobilization stress leads to enhanced anxiety-like behavior in C57Bl/6 mice if the test is employed with a significant time delay. We find this test to be sensitive enough to detect the anxiogenic effects even 10 days after a single episode of 2-h immobilization stress. Our results suggest that the marble burying test could serve as a useful behavioral paradigm for not only estimating the gradual progression of the anxiogenic impact of stress over time, but also raises the possibility of using the temporal delay after stress to test the potential efficacy of post-stress interventions with anxiolytic drugs.