SLC6A3 and irritable bowel syndrome: Since NMDA receptors are expressed in the gut and involved in altered bowel motor function and visceral pain sensation in functional gastrointestinal disorders, such as IBS [27,28], we examined the influence of DAT genetic reduction on NMDA neurotransmission, by evaluating the effect of 100 μM and 1 mM NMDA exposure in isolated ileal segments in Mg++-free conditions.