Transient receptor potential ankyrin1 (TRPA1) is a non-selective cation channel activated by cold stimuli under 17 °C, mechanosensation, and pungent irritants such as allyl isothiocyanates (AITC) and cinnamaldehyde (CA). TRPA1 is located in the sensory terminals of nociceptive fibers in their target organs, such as urinary bladder and the small intestine, and the activation of TRPA1 elicited contractile responses in these organs. However, little is known about the functional role of TRPA1 in non-neural tissues, especially in the gastrointestinal tract. We demonstrated that TRPA1 is highly expressed in enterochromaffin (EC) cells in enteric mucosa, and that TRPA1 stimulation with agonists evokes the release of 5-hydroxytryptamine (5-HT) from EC cells.1) This could produce contraction of guinea-pig ileum by stimulating serotonergic mechanisms. The release of 5-HT from the mucosa and the stimulation of 5-HT3 receptors located in the myenteric plexus may contribute to the TRPA1 agonist-induced contractions in guinea pig ileum. Gastrointestinal (GI) dysmotility and visceral pain/discomfort are the main symptoms of irritable bowel syndrome (IBS). The neurotransmitter 5-HT has been shown to be involved in the pathophysiology of IBS. Especially, postprandial plasma level of 5-HT in patients with IBS with constipation (IBS-C) has been reported to be lower than that in healthy subjects. As mentioned above, we originally found that TRPA1 receptors were expressed on EC cells in GI tract, which are 5-HT releasing cells.1) Therefore, TRPA1 receptor is expected to be involved in GI motility and to be a novel target of the drug for IBS-C. ASP7663 has been newly synthesized in Astellas Pharma Inc. as a novel selective TRPA1 receptor agonist. The compound activated human, rat, and mouse TRPA1 receptors with EC50 values of 0.51(0.40-0.66), 0.54(0.40-0.72), and 0.50(0.41-0.63) µM, respectively. We examined the effect of ASP7663 on constipation using an experimental rodent model of IBS-C.2) Further, the effect of ASP7663 on visceral pain response was also examined. ASP7663 showed anti-constipation effects in Loperamide-induced delay of colonic transit in mice, and analgesic effect in colorectal distension-induced visceral pain responses in rat.3) Consequently, ASP7663 is expected to be a novel and promising therapeutic agent for IBS-C with substantial efficacy in relieving on both constipation and visceral pain symptoms Our results indicate that TRPA1 acts as a sensor molecule for EC cells and may regulate the gastrointestinal function. TRPA1 activation by ingested food containing pungent ingredients, such as mustard oil and cinnamon oil, could promote gastrointestinal motility through these mechanisms. Furthermore, in case of functional GI disorder, such as IBS, TRPA1 receptor agonists hold promise as a beneficial treatment. In addition, our research on the QGP-1 cell line, a new model for the investigation of TRPA1 function in the human EC cell,4) and functional role of TRPA1 in GI motility in dog5) would also be mentioned.