Duodenal-Jejunal Bypass Preferentially Elevates Serum Taurine-Conjugated Bile Acids and Alters Gut Microbiota in a Diabetic Rat Model

Bile acids (BAs) have emerged as important signaling molecules in regulating metabolism and are closely related to gut microbiota. Bariatric surgery elevates serum BAs and affects gut microbiota universally. However, the specific profiles of postsurgical BA components and gut microbiota are still controversial. The aim of this study is to investigate the serum profiles of BA components and gut microbiota after duodenal-jejunal bypass (DJB). DJB and SHAM procedures were performed in a high-fat-diet/streptozotocin-induced diabetic rat model. Body weight, energy intake, oral glucose tolerance test, insulin tolerance test, HOMA-IR, serum hormones, serum BAs, expression of BA transporters, and gut microbiota were analyzed at week 2 and week 12 postsurgery. Compared with SHAM, DJB achieved rapid and durable improvement in glucose tolerance and insulin sensitivity, with enhanced GLP-1 secretion. DJB also elevated serum BAs, especially the taurine-conjugated BAs, with upregulation of BA transporters in the terminal ileum. The phylum level of Firmicutes and Proteobacteria abundance was increased postsurgery, at the expense of Bacteroidetes. DJB preferentially increases serum taurine-conjugated BAs, probably because of more BA reabsorption in the terminal ileum. The gut microbiota is altered with more Firmicutes and Proteobacteria and less Bacteroidetes.