Regulate cholesterol Homeostasis
Bile acids are well recognized as essential for regulating cholesterol homeostasis and the digestion and absorption of fat through the intestine. In recent years, however, bile acids have emerged as crucial signaling molecules with endocrine functions, acting as ligands for the G-protein coupled receptor TGR5 and the nuclear receptor farnesoid X receptor (FXR) resulting in the secretion of GLP-1, PYY and oxyntomodulin from enteroendocrine L-cells. Hence bile acids decrease blood glucose levels and are anorexigenic through PYY and oxyntomodulin, causing weight loss. This has elevated the importance of bile acids beyond fat digestion and into triglyceride, cholesterol, and glucose homeostasis. There is growing interest in bile acids as therapeutic targets for the treatment of obesity, type 2 diabetes, and hyperlipidemia.
The study of bile acid functions requires methods which cover the complexity of this structurally diverse group of molecules. In recent years a number of methods using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) have been developed, which allow analysis of free and conjugated bile acids without derivatization. Most other methods have the disadvantage of time consuming extraction procedures, long analysis times and lack of baseline separation for isobaric species.
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