Effects of unpredictability versus loss of predictability of shock on gastric lesions in rats

Abstract

The relative importance of unpredictability versus loss of predictability of electric tail-shock affecting stress pathology was assessed by using an index of the severity of gastric lesions in male Sprague-Dawley rats. Although repeated sessions of unpredictable shock produced more severe gastric lesions in a greater percentage of rats than did repeated sessions of either predictable or no shock, there was no significant difference, in terms of both incidence and severity of lesions, between lack of predictability and loss of predictability. However, rats exposed first to unpredictable shock and subsequently to predictable shock had significantly fewer lesions than rats exposed continuously to unpredictable shock. The results emphasize only the deleterious effects of shock unpredictability. The effects of changes in predictability of shock on gastric erosions are not clearly supported by the results. © 1984, Psychonomic Society, Inc.. All rights reserved.