Changes in Enterohepatic Circulation after Duodenal–Jejunal Bypass and Reabsorption of Bile Acids in the Bilio-Pancreatic Limb

Background and Aims: Duodenal–jejunal bypass (DJB) shows great effects on weight loss and diabetes improvement. Previously, we reported that the bilio-pancreatic (BP) limb plays an important role in glycemic improvement and in serum bile acid (BA) level increase as reported by Miyachi et al. (Surgery 159(5):1360–71, 2016). This study aimed to investigate the mechanism of BA elevation after DJB and the relationship between these effects and BP-limb length. Methods: Otsuka Long-Evans Tokushima Fatty rats with diabetes were randomly assigned into four groups: one sham group and three DJB groups. Three DJB groups were defined according to the BP-limb length: 0 cm, 15 cm, and 30 cm. The lengths of the alimentary limb and common channel were set equally in each DJB groups. Body weight, glucose tolerance, and BA levels in the liver, bile juice, portal vein, and intestinal contents were assessed postoperatively. Changes in enterohepatic circulation of BAs were assessed using labeled BA. Results: BA elevation after DJB was higher with longer BP-limb. In the 30-cm group, the serum total BA level and BA levels in the portal vein, liver, and bile juice were greater than those in other groups. The enterohepatic circulation was shortened in the 15-cm and 30-cm groups. Conclusions: Shortening of the “enterohepatic circulation” by early reabsorption of BAs in the BP-limb, not by the early influx of bile juice into the ileum, was the main cause of BA elevation after DJB. Thus, glycemic improvement and elevation of BA concentration after DJB depend on the BP-limb length.