Long-term sensitization of cardiovascular stress responses after a single stressful experience.

There is evidence that the experience of traumatic events may play a role in the pathogenesis of somatic diseases, including cardiovascular disorders. In this study, telemetry was used to investigate the long-term effects of a single stressful experience on cardiovascular and behavioral responses to novel challenges 2 weeks later. Rats were exposed to footshocks and tested for sensitization using the following challenges: novel cylinder (Day 14); shock prod acquisition test (Day 15); and shock prod retention test (Day 16). No difference in basal somatomotor activity (SA), heart rate (HR) and blood pressure between preshocked rats and control rats was found. However, preshocked rats displayed an enhanced blood pressure response compared to controls during the shock prod acquisition test and the shock prod retention test. No differential increase in HR response between both groups was found. During the novel cylinder test, the preshocked rats displayed less SA while no behavioral differences were found in the shock prod acquisition test and the shock prod retention test. We conclude that a single stressful experience induces long-term sensitization of blood pressure responses to novel challenges that are not necessarily linked to sensitized behavioral responses. The footshock model may be a useful model to study autonomic hyperresponsivity found in posttraumatic stress disorder (PTSD).