Changes in gastric function and healing of chronic gastric ulcers in aged rats.

The present study was designed to determine the relationship between changes in gastric function caused by aging and the healing of gastric ulcers. Male Fischer-344 rats (young, 2 months; aged, 24-26 months) were used. Gastric ulcers were induced by luminal application of an acetic acid solution (60%, 0.2 ml, 45 sec). The basal and histamine-stimulated gastric acid secretions in aged animals were significantly lower than those in young animals. However, the serum gastrin levels were almost the same in the two groups. Gastric mucosal blood flow and mucosal cell proliferation were also decreased in aged animals. Gastric contractile activity induced by electrical vagal stimulation was almost the same in the two groups, while the gastric relaxative response was significantly reduced in aged animals. The development and healing rate of gastric ulcers in aged animals were almost the same as those in young animals. Histologically, regeneration of the ulcerated mucosa was significantly reduced and tissue contraction occurred in aged animals, as compared to in young animals. We concluded that aging had little or no influence on the development and healing rate of gastric ulcers in rats, but the quality of ulcer healing was quite different between young and aged animals, probably resulting from various gastric dysfunctions related to ulcer healing.