GPBAR1 and Constipation: TGR5 and TRPA1 distributed on intestinal mucosa serve as critical irritant sensors for luminal secondary BAs and mediate ECs secret excessive 5-HT to promote gastrointestinal propulsion.29,31,45 It’s reported that DCA stimulated 5-HT release and promote intestinal propulsion via TGR5 and tgr5-ko mice exhibited obvious constipation.46 Besides, TRPA1 agonist could promote the contraction of ileum by stimulating 5-HT in ECs.47 Initially, both overexpression in colon of PCD mice were revealed in our study.