An extended exposure to shock produces a constellation of behavioral effects collectively known as learned helplessness.
Evidence suggests illness induces hyperalgesia.
Yet, inescapably shocked rats exhibit longer tail-flick latencies to radiant heat. A day after shock treatment, rats were returned to the apparatus and both vocalization and tail-flick latencies were assessed. Previously stressed subjects exhibited lower vocalization thresholds to a noxious thermal stimulus, and outcome indicative of hyperalgesia. As in prior studies, tail-flick latencies were increased. We are currently examining whether the shift in vocalization thresholds is modulated by stressor controllability.