Effect of stressor intensity on habituation and sensitization of glucocorticoid responses in rats.

Studied the effect of stressor intensity on habituation/sensitization of the adrenocortical stress response (ASR) in rats. When lower intensity shock was given, the response first habituated to no-shock control levels but later returned to the same magnitude as seen on the 1st probe day. Plasma corticosterone responses given higher intensity shock never habituated and instead demonstrated an increased response indicative of sensitization. Responsiveness to exogenous adrenocorticotropin 24 hr after the last stress session was monotonically related to the intensity of the stressor presented during the experimental sessions. Data are consistent with the rule from habituation literature that stimulus intensity is inversely related to the magnitude of habituation and extend the dual process theory of P. M. Groves and R. F. Thompson (see record 1971-02046-001) to an endocrine respondent. The data also suggest that an explanation as to the discrepancies in the literature concerning ASR to repeated presentation of stressors may relate to differences in the stressor parameters used. (PsycINFO Database Record (c) 2010 APA, all rights reserved)