Persistent behavioural changes in rats following inescapable shock stress: a potential model of posttraumatic stress disorder.

Behavioural changes in rats two weeks after inescapable shock stress were studied using a shuttle-box task (active avoidance/escape). Rats exposed to inescapable shock stress two weeks beforehand showed more frequent avoidance responses and greater within-group variation in both avoidance response and general activity during the test than rats in a control group. General activity during an unstressful period (before starting the test) did not differ significantly between groups. This relatively prolonged increase in responsiveness to external stimuli in the stressful context may be a useful experimental model of posttraumatic stress disorder, especially in relation to hypervigilance.