Table 1.

The main receptor involved in bile acids signaling.

Receptor	Tissue	Bile Acid	Summary of Implications of High BA Pool	References
FXR	Liver, cholangiocytes, colonocytes, small intestine, heart	CDCA, DCA, LCA	Glucose metabolism and cholesterol metabolism are altered, which result in downregulation of LDL-R expression, increase in LDL-C levels, and upregulation of transcriptional activity of bile acids.	[14,15,16,17]
Others; PXR, LXR, VDR, S1P	Liver and heart	LCA	The receptors regulate hepatic lipid metabolism, activate ERK 1/2, and Akt and then lead to regulation of lipid and glucose metabolism.	[18,19,20,21]
TGR5	Liver, heart, dendritic cells,	TLCA, LCA, DCA, CDCA, CA, UDCA,	Modulates insulin signaling pathway and aids in the regulation hepatic glucose metabolism and inhibition of LPS-induced cytokine expression.	[13,22,23]
Muscarinic	Liver, brain, eyes, heart, and colon carcinoma	Lithocholyltaurine (LCT), TCA	Modulate glucose homeostasis, thermogenesis, inflammatory response, and stimulate parasympathetic nerves.	[24,25]
Sphingosine-1-phospahate (S1P)	Cholangio carcinoma, heart, liver	TCA	Promotes cholangiocarcinoma growth, lipid metabolism, angiogenesis, and cardiac cellular signaling.	[26,27,28,29]
Large conductance voltage- and Ca2+-activated potassium (K+) (BK) channels	Liver and intestinal tract	LCA	Improves vascular muscle cells vasodilation.	[30,31]

BA, bile acid; CDCA, chenodeoxycholic acid; DCA, deoxycholic acid; LCA, lithocholic acid; TLCA, taurolithocholic acid; TCA, taurocholic acid; CA, cholic acid; UDCA, ursodeoxycholic acid; ERK, extracellular signal-regulated kinase; FXR, farnesoid X-receptor; LDL-R, Low-density lipoprotein- receptor; LDL-C, Low-Density lipoprotein- cholesterol; PXR, Pregnane X receptor; LXR, Liver X receptor; VDR, Vitamin D receptor.