Effect of chemically defined diets on antral and serum gastrin levels in rats

When rats were fed isocaloric amounts of chemically defined diets with variable amounts of protein (8-60%) or fat (0-30%) over a 10-day period, their serum and antral gastrin concentrations were, respectively, 60 and 40% lower than the levels of chow-fed rats. It was also determined that neither the low bulk content of these diets nor their inability to adequately buffer the gastric pH contributed to this response. The time course of this dietary-induced reduction in gastrin levels was investigated and it was found that the serum hormone levels were significantly reduced as early as 1-2 h after chow-fed rats were placed on these chemically defined diets. Antral gastrin levels were maintained at normal levels for 4-5 days after rats started consuming these synthetic diets and fell thereafter. With all of the chemically defined diets tested, the gastrin secretory response to a meal was significantly reduced. It therefore appears that synthetic diets lack some undefined food constituent present in chow that is required for the normal postprandial release of gastrin or, alternatively, that they contain an inhibitory factor which blocks the normal secretory response.