What is the Origin of Secondary Bile Acid Signaling?

This concept stems from gastroenterology and endocrinology, highlighting the critical role of the gut microbiome in host physiology. Primary bile acids are synthesized in the liver, but the 'Secondary' designation emphasizes the microbial transformation that generates molecules with distinct signaling capabilities. The discovery of bile acid receptors like FXR and TGR5 cemented this as a major communication axis.

What is the Mechanism of Secondary Bile Acid Signaling?

Secondary bile acids function as ligands for the Farnesoid X Receptor (FXR) and the G-protein-coupled bile acid receptor 5 (TGR5). FXR activation in the liver and intestine regulates bile acid synthesis, glucose, and lipid metabolism. TGR5 activation in the gut and brown adipose tissue enhances energy expenditure and improves insulin sensitivity. This signaling pathway is a direct mechanism for the gut microbiota to exert systemic metabolic control.

Secondary Bile Acid Signaling ∞ Area

Secondary Bile Acid Signaling

Meaning

Secondary Bile Acid Signaling refers to the crucial communication pathways mediated by bile acids that have been chemically modified by the gut microbiota. These microbially-derived secondary bile acids, such as deoxycholic acid and lithocholic acid, act as potent signaling molecules by binding to specific nuclear and membrane receptors throughout the body. This signaling is a key mechanism linking gut microbial health to host metabolism, glucose regulation, and hormonal function.