| BackgroundType 2 diabetes mellitus (T2DM) is a kind of chronic disease that does great harm to human health. Clinical research had showed that bariatric surgeries have rapid and sustained effects in improving T2DM. Recent studies had found that elevated serum bile acid levels following bariatric surgery and which might play an important role in the improvement of glucose tolerance and insulin sensitivity. The change of BA components and its underlying mechanisms may be of great significance during bariatric surgery. The aim of this study is to investigate the effects of different bariatric procedures on serum BA composition and explore the potential mechanisms using a T2DM rat model.MethodsWe established a T2DM rat model by high-fat diet feeding and intraperitoneal injection of low dose streptozotocin. Afterwards, Duodenal-jejunal bypass (DJB), sleeve gastrectomy (SG), and sham operation were performed in diabetic rats, and there were 10 rats in each group. Body weight, food intake, oral glucose tolerance test (OGTT), and insulin tolerance test (ITT) were measured at indicated time points. Serum BAs composition and the expression of cholesterol 7a hydroxylase (CYP7A1), bile acid:CoA synthase (BACS) and bile acid-CoA:amino acid Nacyltransferase (BAAT) at both transcriptional and protein levels in the liver were evaluated at 12 weeks postoperatively.ResultsAt 2 and 12 weeks after operation, the areas under the curves of OGTT and ITT of DJB and SG group were significantly decreased (P<0.05), which indicated that the glucose tolerance and insulin sensitivity were rapidly and sustained improved. At 12 weeks after operation, the serum total bile acids of DJB and SG group were increased (P<0.05), especially the taurine-conjugated BAs, which were elevated in both absolute value and percentage. At 12 weeks after surgery, the expression of CYP7A1 in DJB and SG group was reduced, which prompted that bile acid synthesis was inhibited, and the expression of BACS and BAAT was up-regulated, which suggested that the conjugation with amino acids was enhanced. No obvious difference was detected between DJB and SG except that SG achieved decreased weight gain and food intake.Conclusions1. DJB and SG can effectively improve the glucose tolerance and insulin resistance in T2DM rats.2. Both DJB and SG can increase the serum total bile acid in T2DM rats, especially conjugated bile acids, and there is no significant difference between those two types of operation.3. The expression of BACS and BAAT in liver after SG and DJB was increased, which suggested that conjugated with amino acids was enhanced, and that may be the important reason for the increase of serum conjugated bile acids after bariatric surgeries. |
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