Histopathology and pathogenesis of behaviorally induced gastric lesions in rats.

The development of behaviorally induced acute gastric "stress" ulcers was studied in rats. Rats were first trained to press a bar for food. During either 19 or 29 consecutive days of testing they continued to work for food but were also stressed by mild foot shock. This schedule has previously been shown to be impressively ulcerogenic, though otherwise not physically traumatic. Gastric lesions fell into two histologic classes: an acute ulcerative-hemorrhagic process with several different manifestations and a focal clear cell metaplasia of the gastric pit epithelium. The following explanation is tentatively offered to account for these findings: a) Stress induces constriction of the blood vessels of the muscularis mucosa and results in focal mucosal infarction. b) The gastric pit metaplasia may reflect a response to a stress-induced impairment of the protective mucous coat. In addition, preliminary data suggest that ulceration and healing occur continuously throughout the test period so that no ulcer progresses to perforation.