Influence of aging on gastric ulcer healing activities of cimetidine and omeprazole.

In this study, we compared the effects of cimetidine and omeprazole on the healing of acetic acid-induced gastric ulcers in 8-, 48-, and 96-week-old rats. The repeated oral administration of cimetidine or omeprazole for 14 consecutive days markedly accelerated the ulcer healing in 8- and 48-week-old rats. However, both drugs were ineffective in 96-week-old rats. The basal gastric acid secretion of 8-, 48-, and 96-week-old rats decreased with aging. A single oral administration of cimetidine or omeprazole strongly decreased basal gastric acid secretion in the three different ages of rats. Cimetidine and omeprazole produced a potent and sustained serum gastrin-elevating action in 8- and 48-week-old rats. However, the gastrin-elevating actions of both drugs in 96-week-old rats were much weaker than in the 8- and 48-week-old rats. These results indicate that cimetidine and omeprazole have potent gastric ulcer healing actions in 8- and 48-week-old rats, as well as potent serum gastrin-elevating actions, but both drugs are ineffective in 96-week-old rats, which have lost their gastrin-elevating actions.