BEHAVIORAL STRESS-RESPONSE OF GENETICALLY SELECTED AGGRESSIVE AND NONAGGRESSIVE WILD HOUSE MICE IN THE SHOCK-PROBE DEFENSIVE BURYING TEST/

Genetically selected aggressive and nonaggressive male wild house mice were tested in the shock-probe/defensive burying test. Five distinct behaviors (burying, immobility, rearing, grooming, and exploration) we re recorded in two environmental situations: fresh and home cage sawdu st. Nonaggressive animals, characterized by a Long Attack Latency (LAL ), showed more immobility in both test situations than animals having Short Attack Latencies (SAL), whereas SAL males displayed more defensi ve burying than LAL ones when tested with fresh sawdust. Testing;with home cage sawdust, however, resulted in the same duration of defensive burying in SAL and LAL. These results support earlier findings about the existence of two heritable, fundamentally different strategies to cope with aversive situations. Aggressive (SAL) animals react actively to environmental challenges, whereas nonaggressive animals react acti vely or passively, depending on the characteristics of the stressful e nvironment. These mouse lines, selected for attack latency, i.e., aggr ession, may, therefore, be important tools to unravel the genetic arch itecture underlying the physiological and neuronal mechanisms of behav ioral strategies towards stressful events.