GENETIC-DIFFERENCES IN THE MOUSE DEFENSE TEST BATTERY

The mouse defense test battery (MDTB) has been designed to examine anx iogenic- or anxiolytic-like properties of psychoactive drugs through e ffects on specific defensive behaviors. In the present study, the MDTB was used to evaluate the potential contribution of genetic factors to these behaviors. The data revealed pronounced differences in several defense reactions among four inbred strains (BALB/c, C57BL/6, CBA, DBA /2) and one outbred (Swiss) mouse line. Thus, when subjects were intro duced into the apparatus, Swiss and C57BL/6 displayed the highest leve ls of horizontal and vertical activities, while BALB/c and DBA/2 mice showed intermediate and CBA low activity rates. When subjects were cha sed by the rat, C57BL/6 mice used flight as the dominant defense strat egy, while the defensive responses of BALB/c, C57BL/6, and DBA/2 mice consisted of flight reactions and risk assessment activities. However, when flight or escape was not possible, risk assessment became the pr edominant feature of the defense repertoire in the C57BL/6 mice. When defensive threat/attack behaviors were required, Swiss, BALB/c, DBA/2, and C57BL/6 mice showed very similar reactions in terms of the magnit ude of the responses observed. CBA mice were poorly defensive in all t hese test situations. Finally, after the rat was removed from the test apparatus, Swiss, DBA/2, and C57BL/6 mice displayed more vertical act ivities than BALB/c mice. These latter, however, showed an increased l evel of ambulation compared to the activity recorded before the rat ex posure. Together, these findings indicate that genetic factors contrib ute to defensive behaviors in this animal model of anxiety. The differ ent behavioral profiles displayed by the strains used here may provide the means to obtain a better insight into the neurobehavioral mechani sms involved in anxiety-related disorders. (C) 1997 Wiley-Liss, Inc.