Abstract #45

# 45
The emerging role of bile acids as nutrient-sensing signals.
Ignacio R. Ipharraguerre*1,2, 1Institute of Human Nutrition and Food Science, University of Kiel, Kiel, Germany, 2Lucta S.A, Montornes del Valles, Spain.

Traditionally, bile acids (BA) have been viewed as detergent molecules involved in the intestinal digestion and absorption of lipids and hepatic maintenance of cholesterol homeostasis. During the last 15 years, however, it has become clear that BA are important regulatory molecules with systemic endocrine functions that signal changes in luminal nutrients and microbial activity during the fed-fast cycle. The regulatory actions of BA are primarily mediated by the nuclear receptor FXR (farnesoid X receptor), the G-protein coupled receptor TGR5 and cellular signaling pathways (AKT and ERK1/2). These proteins are highly expressed in the liver as well as enterocytes, endocrine cells and enteric neurons in the small intestine. Surprisingly, BA receptors are also present in several tissues outside the biliary tree including adipose tissue, pancreas, and immune cells. In mice, via interaction with these sensors and pathways, BA control the expression of genes and concentration of circulating hormones involved in the regulation of lipid and glucose metabolism, energy expenditure, intestinal integrity, motility, and immune homeostasis, gut microbial growth, and inflammation. In pigs, evidence from seminal studies indicates that BA signaling is implicated in the intestinal secretion of glucagon-like peptides, gut mucosal growth and protection, nutrition-related liver disease, and changes in host weight and metabolism resulting from variations in gut microbiota. It is important to note that BA differ in their ability to activate signaling pathways and that the composition of the BA pool varies remarkably among non-ruminant animals. In fact, all non-ruminant species of interest (e.g., pig, chicken, rabbit, horse) have unique BA signatures. In view of these differences and the emerging role of BA as regulatory molecules, the study of their involvement in signaling outside the enterohepatic circulation and in mediating reciprocal communication between the host and its microbiota will become a relevant and expanding field of research in animal nutrition and physiology.

Key Words: bile acid signaling, FXR, TGR5

Speaker Bio
Ignacio Ipharraguerre currently holds a research position at the Institute of Human Nutrition and Food Science, University of Kiel, Germany and leads the Innovation Division at Lucta, Spain. He received a degree in Agricultural Sciences from University of Buenos Aires, Argentina in 1995.  After serving 3 years as Technical Consultant in Argentina, he began his graduate studies at the University of Illinois where he obtained the M.S. (2001) and Ph.D. (2004) degrees in Animal Sciences. Ignacio joined Cargill Animal Nutrition in 2005 as Innovation Development Manager (USA) and, two years later, he decided to continue his professional career in Europe.