The effect of cage shelf on the behaviour of male C57BL/6 and BALB/c mice in the elevated plus maze test.

The effect of environmental enrichment in the form of a cage shelf on the behaviour of male C57BL/6 and BALB/c mice was compared. Male C57BL/6 and BALB/c mice were randomly allocated into 12 cages per strain. The mice were kept in control conditions or exposed to a cage shelf for two, four, six or eight weeks, and thereafter assessed with the elevated plus maze. C57BL/6 mice displayed a trend of being less anxious than the BALB/c mice. A cage shelf increased the number of entries made into the open arms and the total number of entries only in the case of the C57BL/6 mice, but had no effect on the behaviour of the BALB/c mice. In conclusion, the effect of a cage shelf on the elevated plus maze behaviour of mice depends on the strain of the animals.