Table 1.

Functional roles of bile acid receptors in the gut.

Section	Receptor	Major functions in the intestine	Consequences of loss of function	Selected references
	Nuclear receptors
2.1	Farnesoid X receptor (FXR)	• Bile acid and cholesterol homeostasis via ileal FGF15/19 • Suppression of mucosal immune response • Maintenance of intestinal barrier	• Increased susceptibility to intestinal inflammation • Bacterial overgrowth • Increased bile acid production, bile acid diarrhea • Promoting colorectal tumorigenesis	3,6,7
2.2	Vitamin D receptor (VDR)	• Detoxification • Modulation of bile acid biosynthesis via FGF15/19		3,30
2.2	Pregnane X receptor (PXR)	• Detoxification		3,36
2.2	Constitutive androstane receptor (CAR)	• Detoxification		3,36
	Membrane receptors
3.1	Takeda G protein-coupled receptor (TGR5; GPBAR1)	• Delayed gastric emptying • Increased colonic motility • Anti-inflammatory response • Induction of incretin secretion and modulation of glucose homeostasis via GLP-1	• Disturbed motility that varies between intestinal regions • Reduced frequency of defecation • Low stool water content • Disturbed glucose homeostasis?	37,54,77
3.2	Muscarinic acetylcholine receptor M3 (M3R)	• Cell proliferation		87
3.3	Sphingosine-1-phosphate receptor 2 (S1PR2)	• Hepatic lipid homeostasis • Cell proliferation?		90,94