Differences in anxiety-related behavior and response to diazepam in BALB/cByJ and C57BL/6J strains of mice.

The study in an ethological perspective of inbred strains of mice offers a more accurate description of anxiety-related behavior. In this context, behavioral performances of the BALB/cByJ and C57BL/6J strains were systematically compared in the staircase test, the light/dark test and the elevated plus maze test. A rarely used variable, the latency of the first entry in the dark box, was also recorded in the light/dark test. A new statistical approach to this measure meant that specific avoidance strategies could be differentiated in the two strains. A study of the behavioral responses of the two strains given treatment with diazepam, a widely used anxiolytic compound, was also carried out. Results showed substantial differences between BALB/cByJ and C57BL/6J strains. C57BL/6J mice had high baseline activity and exploration of a new environment, suggesting a low level of anxiety. BALB/cByJ mice displayed defensive and protective behavior, with limited exploration of the new environment together with low locomotor activity. The response to diazepam was also different for each strain: C57BL/6J mice showed higher sensitivity to diazepam treatment than did BALB/cByJ mice.