effect of gastric secretagogues during ontogenesis in rats

The effects of histamine, bethanechol and pentagastrin on gastric acid secretion were studied in rats of younger and older age groups. After 48 hours starvation, the pylorus was ligated and each of the secretagogues was administered subcutaneously to individual groups. Four hours later the animals were sacrified by chloroform-induced asphyxia and the stomach was removed after ligating the cardiac end. The stomach contents, obtained by flushing with 3 ml of distilled water, were used to determine the volume of gastric juice and its free and total acidity. Histamine and bethanechol produced a greater increase in the volume and acidity of gastric juice in older animals as compared to younger ones. Pentagastrin also produced greater increase in these parameters in older animals but it was not statistically significant. Possible explanation of these results include variable size of parietal cell mass and/or difference in the sensitivity of parietal cells to individual secretagogues in animals of different age groups