Age-related topographical metabolic signatures for the rat gastrointestinal contents

Symbiotic gut microbiota is essential for mammalian physiology and analyzing the metabolite compositions of gastrointestinal contents is vital for understanding the microbiome-host interactions. To understand the developmental dependence of the topographical metabolic signatures for the rat gastrointestinal contents, we systematically characterized the metabolite compositional variations of the contents in rat jejunum, ileum, cecum, and colon for two age-groups using ¹H NMR spectroscopy and multivariate analysis. Significant topographical metabolic variations were present for the jejunal, ileal, cecal, colonic contents, and feces, reflecting the absorption functions for each intestinal region and the gut microbiota therein. The concentrations of amino acids, lactate, creatine, choline, bile acids, uracil and urocanate decreased drastically from jejunal to ileal contents followed with steady decreases from cecal content to feces. Short-chain fatty acids (SCFAs) and arabinoxylan-related carbohydrates had highest levels in cecal content and feces, respectively. Such topographical metabolic signatures for the intestinal contents varied with animal age highlighted by the level changes for lactate, choline, taurine, amino acids, carbohydrates, keto-acids, and SCFAs. These findings provided essential information for the topographical metabolic variations in the gastrointestinal tract and demonstrated metabolic profiling as a useful approach for understanding host-microbiome interactions and functional status of the gastrointestinal regions.