INTERINDIVIDUAL VARIABILITY IN SWISS MALE-MICE - RELATIONSHIP BETWEENSOCIAL-FACTORS, AGGRESSION, AND ANXIETY

In the present study we carried out a series of experiments in Swiss a lbino male mice to investigate a) the effects of previous social exper ience on the levels of anxiety in the elevated plus-maze (EPM) and b) whether the response of males in the EPM differs in relation to the di fferent social status. In Experiment 1 we tested in the EPM male mice that received different social experience Results showed that individu ally housing generally increased measures of anxiety in the EPM compar ed with the group-housing condition. Moreover, aggressive males, scree ned during dyadic encounters in a neutral cage, displayed the highest levels of anxiety relative to the other experimental conditions. In Ex periment 2 male mice remained group-housed and were observed to record their social status. Results showed that those animals rated as socia lly dominant displayed a higher level of EPM anxiety relative to subor dinates. From an ethological perspective our findings may be interpret ed in terms of coping strategies, with aggressive/dominant animals typ ified by higher levels of risk assessment and open-arm avoidance than defensive/subordinate animals. (C) 1998 Elsevier Science Inc.