Effects of aging on gastrin and somatostatin secretion from isolated perfused rat stomach

We have examined the release of gastrin and somatostatin from the isolated perfused stomach of rats of three different age groups (4 months, 12 months, and 24 months old) in response to bombesin and carbachol. The basal release of gastrin was diminished in 24-month-old rats. Basal somatostatin release showed an age-related decrease. Bombesin (10(-10) and 10(-9) M) and carbachol (10(-8) and 10(-7) M) stimulated gastrin release in each age group. The integrated release of gastrin in response to bombesin (10(-10) and 10(-9) M) or carbachol (10(-8) M) did not differ among the three age groups, although integrated gastrin release in response to carbachol (10(-7) M) decreased in 24-month-old rats. Bombesin-stimulated release of somatostatin decreased in 12- and 24-month-old rats. Carbachol inhibited release of somatostatin in each age group. Compared with 4-month-old rats, the inhibition of somatostatin release by carbachol was less in 24-month-old rats at 10(-8) and 10(-7) M, and less in 12-month-old rats at 10(-7) M. The decreased basal gastrin secretion and well-preserved gastrin response were further confirmed in conscious aged rats tested by means of oral gavage with 10% peptone. Our findings indicate that gastrin response to the stimuli is well preserved with aging, whereas the response of somatostatin diminishes in an age-related manner. Aging has different effects on the release of gastrin and somatostatin from the rat stomach.