Psychoneurogastroenterology: interrelations in stress-induced colonic motility and behavior.

Individual differences in behavioral and physiological response patterns to stress may contribute to vulnerability for stress-related illnesses such as functional gastrointestinal disorders. Animal models could give clues about specific individual determinants of intestinal reactivity to stress and stress-induced sensitization. Rats fitted with permanent electrodes on the proximal colon were exposed to a single session of foot shocks (10 x 6 s in 15 min, preshocked) or no shocks (control). Two weeks later, the preshocked group showed a significantly greater colonic spike burst response to a novel shock-prod stressor in the home cage than controls. The increase in burst frequency was positively correlated with the duration of active burying of the threatening prod in both experimental groups, but not with other behavioral components. Basal colonic burst frequency at rest was negatively correlated with the increase in burst frequency due to shock-prod stress in both groups, but the degree of sensitization in preshocked rats vs. controls was of similar magnitude in rats with low and high basal colonic burst frequency. The results indicate that colonic responsivity to stress is related to both basal motility status and individual coping strategies.