Time‐dependent Component‐specific Regulation of Gastric Acid Secretion‐related Proteins by Roasted Coffee Constituents

Abstract

Consumption of coffee beverages has been reported to cause gastric irritation in some consumers as a result of increased gastric acid secretion. In the complex mechanisms of gastric acid secretion, the activity and expression of the H+,K+‐ATPase is regulated by transmitters, such as histamine, acetylcholine, gastrin, somatostatin, and their corresponding receptors. Here, we report the effect of three coffee constituents, chlorogenic acid, caffeine, and N‐methyl pyridinium ions, on the expression of the histamine receptor H2, the acetylcholine receptor M3, the gastrin receptor, the somatostatin receptor, and the H+,K+‐ATPase. Human gastric cancer cells were exposed to chlorogenic acid, caffeine, or N‐methyl pyridinium in their coffee brew‐representative concentrations as well as to physiological stimulators of gastric acid secretion. Gene expression levels of receptor proteins and those of the H+,K+‐ATPase were measured at different time points by real‐time PCR. Expression of prosecretory receptors significantly increased between one and one‐half to twofold after treatment with chlorogenic acid or caffeine compared to control cells at the same time point. Chlorogenic acid and caffeine also increased the H+,K+‐ATPase gene expression twofold higher compared to control cells. In contrast, N‐methyl pyridinium downregulated the expression of the prosecretory gastrin receptor significantly, by −27%. In conclusion, chlorogenic acid, caffeine, and N‐methyl pyridinium impair the expression of gastric acid secretion‐related proteins in a time‐dependent manner. Future work will be aimed at the elucidation of the cooperative interplay of individual components using recombinates of single coffee constituents.