DEPRESSIVE BEHAVIOR AND STRESS-ULCER IN WISTAR-KYOTO RATS

Wistar Kyoto (WKY) rats, as compared to several other rat strains, are hypoactive in the open field test and in the defensive burying test. WKY rats readily acquire a learned helplessness task as well as a pass ive avoidance tasks. WKY rats also reveal a greater susceptibility to restraint-induced stress ulcer. The behavioral tests suggest the prese nce of depressive behavior in WKY rats. When exposed to the Porsolt fo rced-swim test of 'behavioral despair', WKY rats are judged as exhibit ing more depressive behavior. Desipramine not only reduced immobility in the forced-swim test, but also diminished the severity 6f restraint -induced stress ulcer. These data suggested a heightened activity of t he hypothalamic-pituitary axis. Basal plasma ACTH levels did not diffe r between WKY rats and Wistar rats, but serial plasma ACTH response to restraint stress was significantly greater for WKY rats. These data s uggest that depressive behavior is a characteristic of WKY rats and th is strain is a valuable model for studying depression which may be ind uced by an exaggerated stress response.