The role of bile acids in regulating glucose and lipid metabolism

In recent years, bile acids (BAs) are increasingly being appreciated as signaling molecules beyond their involvement in bile formation and fat absorption. The farnesoid X receptor (FXR) and the G protein-coupled bile acid receptor 1 (GPBAR1, also known as TGR5) are two dominating receptors through which BAs modulate glucose and lipid metabolism. FXR is highly expressed in the intestine and liver. GPBAR1 is highly expressed in the intestine. The present study reviews the metabolism and regulation of BAs, especially the effects of BAs on glucose and lipid metabolism by acting on FXR in the liver and intestine, and GPBAR1 in the intestine. Furthermore, it explains that fibroblast growth factor 15/19 (FGF15/19), ceramide, and glucagon like peptide-1 (GLP-1) are all involved in the signaling pathways by which BAs regulate glucose and lipid metabolism. This article aims to provide an overview of the molecular mechanisms by which BAs regulate glucose and lipid metabolism, and promote further scientific and clinical research on BAs.