Measuring anxiety- and locomotion-related behaviours in mice: a new way of using old tests.

RATIONALE

Batteries of tests that are thought to measure different aspects of anxiety-related behaviour are used to characterise mice after genetic or pharmacological manipulation. However, because of the potentially confounding effects of repeated testing and natural intra-individual variations in behaviour over time, subjecting mice to a succession of tests is not ideal.

OBJECTIVES

The aim of this study was to investigate, in mice, the utility of an integrated apparatus that combines three classical tests of anxiety, the open field, elevated plus maze (EPM) and light/dark box.

METHODS

Mice from four different strains (CD-1, BALB/cJ, DBA/2J, C57BL/6J) were used in a series of five experiments where their behaviour was observed for 15 min in the integrated apparatus. Responses to anxiety-modulating drugs and 2-day repeated testing were evaluated.

RESULTS

CD-1 mice explored the apparatus thoroughly, providing measures from all areas throughout the entire testing session. Factor analysis showed that measures of locomotion and anxiety-related behaviour were dissociable. BALB/cJ, DBA/2J and C57BL/6J showed markedly different behavioural profiles, largely consistent with previous studies examining individual tests. Avoidance of aversive environments did not increase with repeated testing. In CD-1 mice, the anxiolytics diazepam and alprazolam (4 and 2 mg/kg, respectively) increased the approach towards the EPM open arms. Alprazolam also had sedative effects, whereas the anxiogenic pentylenetetrazole had no effects.

CONCLUSIONS

These findings suggest that the triple test is sensitive to genetic/pharmacological influences on anxiety and locomotion and that, by providing quasi-simultaneous measures from three different apparatuses, it may represent an alternative to the use of test batteries.