Diunsaturated Aldehyde, trans,trans-2,4-Decadienal in the Intestinal Lumen Suppresses Gastric Emptying through Serotonin Signaling in Rats.

We recently demonstrated that a diunsaturated aldehyde, trans,trans-2,4-decadienal (2,4-decadienal), potently stimulated secretion of cholecystokinin in the enteroendocrine cell line. Gut hormones such as cholecystokinin and serotonin play critical roles in reducing postprandial gastric emptying. In the present study, we first demonstrated that oral administration of 2,4-decadienal (50-100 mg/kg) reduced gastric emptying rate in rats, assessed by both the acetaminophen absorption test and the phenol red recovery method. In contrast, saturated aldehyde, alcohol, and fatty acids having the same chain length as 2,4-decadienal did not affect the gastric emptying rate. Duodenal administration of 2,4-decadienal potently reduced gastric emptying rate, but intraperitoneal administration did not. Furthermore, the gastric inhibitory effect of 2,4-decadienal was attenuated by treatment with a serotonin receptor antagonist. These results demonstrated that 2,4-decadienal in the small intestinal lumen has a potent inhibitory effect on gastric emptying, possibly through stimulation of the serotonin-producing enteroendocrine cells.