Abstract
The gastrointestinal (GI) tract demonstrates a number of changes that accompany advanced age. In the present study, we investigated gastric acid secretion in young and old mice in response to chemical stimulation and mechanical stimulation. Gastric acid secretion was measured in anesthetized mice. Proton pump (H+,K+ ATP ase) is a good maker of the parietal cell function, therefore, protein expression of proton pump was determined by Western blotting. After 60 min basal collection, acid secretion was stimulated by histamine (500 and 1000 mg/kg) or carbachol (10 and 20 mg/kg). To investigate the response to mechanical stimulation, the stomach was distended by an intragastric injection of isotonic saline (0.5, 1.0, 1.5 and 2.0 ml). 1) Administration of 2 doses of histamine produced a dose-dependent increase in acid secretion in young mice, whereas a higher dose of histamine could not produce a significant increase in acid secretion in old mice. 2) Stimulatory effect of carbachol on gastric acid secretion did not differ between young and old mice, although the mean values tended to be lower in old animals than in the young. 3) The response to mechanical stimulation tended to be lower in old animals. 4) Protein expression of H+, K+ ATPase was significantly lower in old mice than the young. The present study showed that gastric acid secretion was different between young and old mice concerning to various kinds of stimulations. The decrease in the secretory function of the stomach in the old mice is partly associated with a decrease in parietal cells (H+,K+ ATPase ). [J Physiol Sci. 2006;56 Suppl:S142]
