Unsaturated aldehydes induce CCK secretion via TRPA1 in STC-1 cells.

Scope Cholecystokinin (CCK) producing cells sense luminal contents to regulate the exocrine pancreas, gastric motility, and appetite. Although long-chain fatty acids (FAs, ≥ C12) are well known to stimulate CCK secretion, the CCK-releasing activities of other aliphatic compounds, such as aldehydes (Alds) or alcohols (Alcs), have not been studied. Methods and results We tested the CCK-releasing activities of various aliphatic compounds with various carbon chain lengths (C3-C13) and degrees of unsaturation in the enteroendocrine cell line STC-1. CCK released from the cell was measured using an ELISA, and intracellular calcium concentration was measured using Fura-2. Mono- and di-unsaturated Alds at 100 μM, but not saturated Alds, induced CCK secretion in STC-1 cells. Alcs and FAs failed to induce CCK secretion, regardless of carbon chain length or degree of unsaturation. Unsaturated Alds increased intracellular calcium concentration, but saturated Alds, Alcs, and FAs did not. Intracellular calcium mobilization and CCK secretion induced by unsaturated Alds was abolished in the absence of extracellular calcium. In addition, the inhibition of the transient receptor potential ankyrin 1 (TRPA1) channel suppressed unsaturated Ald-induced CCK secretion and intracellular calcium mobilization. Conclusion Unsaturated Alds are potent aliphatic stimulants for CCK secretion through the activation of TRPA1.