Stressor-provoked behavioral changes in six strains of mice

Behavioral changes induced by inescapable shock were examined in six strains of mice. Exposure to shock provoked time-dependent disturbances of shuttle escape performance. In some strains the shock treatment did not affect escape performance, whereas in others profound performance deficits were evident. The inescapable shock treatment likewise induced strain-dependent alterations of performance in a forced-swim task. In most instances the shock treatment initially provoked invigorated responding, but in other strains the shock had no effect or depressed active responding. Finally, Y-maze spontaneous alteration performance was not affected by the shock treatment, although a strain-dependent increase of perseverative responses was evident. The occurrence of a stressor-induced deficit in one task in a particular strain of mouse was not predictive of behavioral alterations in a second task. These data are discussed with respect to animal models of depression and genetic differences associated with the response to stressors.