Acute stress disrupts risk assessment behavior in mice

The effects of stress on risk assessment behavior in mice were studied by examining latency to emerge from a safe compartment into a large, well-lit open field. In the first experiment different groups of mice were exposed for 1 h to tube restraint, fixed interval 2-min foot shock, or attack by an aggressive conspecific. Nonstressed controls were left undisturbed in the home cage. Thirty minutes following stress animals were placed in the safe compartment and latency to emerge was recorded. Results showed all of the stressed groups exhibited significantly faster emergence latencies than nonstressed controls. In the second experiment the duration of this effect was examined by testing different groups at varying intervals following tube restraint stress. Results showed that mice tested 0.5 and 1 h following stress exhibited short entry latencies and reduced head poke responses. Performance had returned to nonstress levels 3 h after stress. These data suggest that stress reduces caution by disrupting risk assessment behaviors.