Abstract: As an important component of bile, bile acid is synthesized by the liver using cholesterol as a raw material. It can be excreted into the digestive tract together with bile under the stimulation of exogenous food and related hormones. Bile acids can emulsify fat, promote intestinal absorption of lipids, and regulate liver and intestine functions, increasing energy consumption, improve insulin sensitivity. The bile acid, generally can be synthesized in two ways, the classical route and the alternative route. The enterohepatic circulation can recycle about 95% of the bile acids synthesized from the beginning, and only 5% which can be refilled through alternative ways to ensure the dynamic balance of the bile acid pool will be lost. Therefore, the enterohepatic circulation plays a vital role in regulating the homeostasis of bile acids. With the deepening of research, the metabolism and transport mechanisms of bile acids have been gradually clarified, and the functions of transporters involved in the enterohepatic circulation have become more clear in recent years. The farnesoid X receptor (FXR), as an important nuclear factor, can regulate the expression of bile acid transporter through small heterodimer receptor (SHP), retinoic acid receptor α (RARα), combined with fibroblast growth factor 15/19 (FGF15/19), and then affects bile acids homeostasis. This article describes the significant transporters involved in the enterohepatic circulation of bile acids and the regulatory mechanism of FXR, which will provide a theoretical basis for further exploration of bile acid functions in the future.

Key words: bile acids transporter, enterohepatic circulation, FXR