Influence of aging on stress ulcer formation in rats

The effects of aging on stress ulcer formation were examined in male Fischer 344 rats at 2, 8-9, 11-12, 17-18 and 21-24 months old. The animals were restrained and immersed in a water bath (22 degrees C) for 1, 2, 4 and 8 h. The incidence and severity of gastric corpus ulceration increased linearly with age. Basal acid secretion, determined 4 h after pylorus ligation, decreased with age, but there were no age-related differences in the effect on acid secretion of histamine and vagal nerve stimulation in the lumen-perfused stomachs of anesthetized rats. On morphological examination, surface epithelial cells in aged rats (21-24 months) were found to be intact, but the gastric foveolae were shallow and the chief cell layer was thick in aged rats. Deficiencies of vascular networks were observed in aged rat stomachs. These results indicate that an insufficiency of gastric mucosal microvascular networks and the preserved gastric acid response in the vulnerable mucosa may be involved in the mechanisms underlying aggravation of stress ulcer formation in aged rats.