Abstract: Bile acids not only contribute to digestion and nutrient absorption,but also have recently been shown to be a signaling molecule involved in the regulation of multiple physiological functions through the activation of corresponding receptors,such as lipid metabolism,glucose metabolism and energy metabolism.The gut-brain axis is a two-way signal system composed of the gastrointestinal tract and the central nervous system,which not only integrates the functions of the gut and the central nervous system,but also organically connects them.Bile acids interact with the gut to some extent,and the gut microbiota is the key factor of the interaction between bile acids and the gut,and also the important factor of the gut-brain axis.The effects of bile acids in different concentrations on the intestinal tract are different.The effects of bile acids on the intestinal tract are mainly reflected in their effects on the intestinal microbes,a large part of the effect of the gut on bile acids is also due to gut microbes.At present,many researches focus on the interaction between bile acids and gut microbes.In addition,bile acids and bile acid receptors have also been found in the brain,suggesting that bile acids may play a physiological role in central nervous system.Bile acids can directly or indirectly signal the central nervous system to affect various brain functions.A variety of gut hormones,vagus nerves and bile acid receptors are involved in this process,among which bile acid receptors play an important role.More and more studies show that there are complex interactions between bile acids,brain,gut and gut microbes.Bile acids may be one of the direct communication channels between gut and brain,and have potential effects on gut-brain axis.In this paper,the effects of bile acids and their receptors in the gut and brain were reviewed,and the research progress of bile acids in the gut-brain axis was introduced.

Key words: bile acid; gut-brain axis; bile acid receptor