Published online Aug 21, 2022. doi: 10.3748/wjg.v28.i31.4338
Peer-review started: May 26, 2022
First decision: June 19, 2022
Revised: June 28, 2022
Accepted: July 25, 2022
Article in press: July 25, 2022
Published online: August 21, 2022
Processing time: 82 Days and 2.6 Hours
Duodenal-jejunal bypass (DJB) induces rapid and significant amelioration of type 2 diabetes mellitus in various diabetic rat models, while the mechanisms have not been fully elucidated. Duodenal SIRT1 regulates hepatic glucose production and hepatic insulin sensitivity through a gut-brain-liver axis, and activation of bile acid (BA) receptors promotes SIRT1 expression in many tissues. This study aimed at uncovering the roles of duodenal BAs and SIRT1 in the diabetic control after DJB.
To expand and deepen our understanding on the mechanisms underlying diabetes control after DJB, and to provide new ideas and targets for the non-surgical treatment of diabetes in the future.
To investigate the effects of DJB on the duodenal BA signaling pathway and SIRT1 expression in a diabetic rat model, and further reveal the roles of BAs in modulating SIRT1 expression in enterocytes.
DJB and sham surgeries were performed on rats with diabetes induced by high-fat diet and low-dose streptozotocin. The effects of surgeries on metabolic parameters were compared accordingly. The intraduodenal BA concentration, the key genes of BA signaling pathway and SIRT1 in the duodenal mucosa were evaluated 8 wk postoperatively. Rat small intestine epithelial IEC-6 cells were treated with GW4064 and INT-777 to verify the effects of BA receptor activation on SIRT1 expression in enterocytes.
DJB rapidly and dramatically improved glucose homeostasis in the diabetic rats independently of body weight and food intake. DJB increased both systemic and intraduodenal total BAs, activated the BA signaling pathway and promoted SIRT1 expression in the duodenum mucosa. Activation of BA receptors including farnesoid X receptor and Takeda G-protein-coupled receptor 5 increased the mRNA and protein expression of SIRT1 in IEC-6 cells.
DJB increases intraduodenal BA levels and activates the duodenal BA signaling pathway, which may further contribute to the improved hepatic insulin resistance and glucose homeostasis by upregulating SIRT1 expression in the duodenal mucosa.
Our findings provide evidence that BA-mediated upregulation of SIRT1 in the duodenum contributes to the diabetic control after DJB. This study also implicates that duodenal BAs and SIRT1 might be potential targets for improving hepatic insulin sensitivity and systemic glucose homeostasis, which lays the groundwork for developing duodenal BA and SIRT1-specific treatments to alleviate diabetes.