Additional effects of duodenojejunal bypass on glucose metabolism in a rat model of sleeve gastrectomy

Duodenal-Jejunal Bypass Restores Sweet Taste Receptor-Mediated Glucose Sensing and Absorption in Diabetic Rats

Aim: The aim of the study is to identify the regulatory role of intestinal sweet taste receptors (STRs) and glucose transporters (SGLT1, GLUT2) and gut peptide secretion in duodenal-jejunal bypass (DJB)-ameliorated glycemic control in Type 2 diabetes. Materials and Methods: DJB and sham surgeries were performed in streptozotocin-induced diabetic male rats. The blood GLP-1 and GLP-2 levels were evaluated under feeding and fasting conditions. The expression of STRs (T1R2, T1R3), sweet taste signaling effector (Gα-gustducin), SGLT1, and GLUT2 was detected in the intestinal alimentary limb (A limb), biliopancreatic limb (BP limb), and common limb (C limb). The effects of STR inhibition on glucose control were measured with lactisole. Results: Glucose tolerance was improved in DJB-operated rats compared with the sham group, similar to that of normal control rats, without significant differences in food intake and body weight. The plasma GLP-1 levels of DJB rats were increased under diet-fed condition, and GLP-2 levels were increased after fasting. The villus height and crypt depth were significantly increased in the A limb of DJB-operated rats. In addition, GLP-1 expression was restored in enterocytes. The expression of T1R2, Gα-gustducin, and SGLT1 was elevated in the A limb after DJB, while GLUT2 was downregulated in the A, BP, and C limbs. The localization of GLUT2 was normalized in the three intestinal limbs after DJB. However, the beneficial effects of DJB on glucose control were abolished in the presence of lactisole in vivo. Conclusion: DJB ameliorates glycemic control probably by restoring STR-mediated glucose sensing and absorption with the responses of GLP-1 and GLP-2 to carbohydrate.

Intestinal glucose excretion: A potential mechanism for glycemic control

The gut has been increasingly recognized in recent years as a pivotal organ in the maintenance of glucose homeostasis. Specifically, the profound and enduring improvement in glucose metabolism achieved through metabolic surgery to modify the anatomy of the gut has prompted scholars to acknowledge that the most effective strategy for treating type 2 diabetes mellitus (T2DM) involves the gut. The mechanisms underlying the regulation of glucose metabolism by the gut encompass gut hormones, bile acids, intestinal gluconeogenesis, gut microbiota, and signaling interactions between the gut and other organs (liver, brain, adipose, etc.). Recent studies have also revealed a novel phenomenon of glucose lowering through the gut: metabolic surgery and metformin promote the excretion of glucose from the circulation into the intestinal lumen by enterocytes. However, there is still limited understanding regarding the underlying mechanisms of intestinal glucose excretion and its contribution to glycemic control. This article reviews current research on intestinal glucose excretion while focusing on its role in T2DM management as well as potential mechanisms.

Transcriptome Changes and Metabolic Outcomes After Bariatric Surgery in Adults With Obesity and Type 2 Diabetes

Context

Bariatric surgery has been shown to be effective in inducing complete remission of type 2 diabetes in adults with obesity. However, its efficacy in achieving complete diabetes remission remains variable and difficult to predict before surgery.

Objective

We aimed to characterize bariatric surgery-induced transcriptome changes associated with diabetes remission and the predictive role of the baseline transcriptome.

Methods

We performed a whole-genome microarray in peripheral mononuclear cells at baseline (before surgery) and 2 and 12 months after bariatric surgery in a prospective cohort of 26 adults with obesity and type 2 diabetes. We applied machine learning to the baseline transcriptome to identify genes that predict metabolic outcomes. We validated the microarray expression profile using a real-time polymerase chain reaction.

Results

Sixteen patients entered diabetes remission at 12 months and 10 did not. The gene-expression analysis showed similarities and differences between responders and nonresponders. The difference included the expression of critical genes (SKT4, SIRT1, and TNF superfamily), metabolic and signaling pathways (Hippo, Sirtuin, ARE-mediated messenger RNA degradation, MSP-RON, and Huntington), and predicted biological functions (β-cell growth and proliferation, insulin and glucose metabolism, energy balance, inflammation, and neurodegeneration). Modeling the baseline transcriptome identified 10 genes that could hypothetically predict the metabolic outcome before bariatric surgery.

Conclusion

The changes in the transcriptome after bariatric surgery distinguish patients in whom diabetes enters complete remission from those who do not. The baseline transcriptome can contribute to the prediction of bariatric surgery-induced diabetes remission preoperatively.

Changes of Short-Chain Fatty Acids and Their Receptors in an Obese Rat Model After Sleeve Gastrectomy

BACKGROUND

Short-chain fatty acids (SCFAs) and gut microbiota have health-related effects and are associated with a wide range of disorders. However, the changes of SCFAs and their receptors after sleeve gastrectomy (SG) remain unclear. This study aimed to examine changes of SCFAs and their receptors after SG in an obese rat model.

METHODS

Thirty obese Sprague-Dawley rats eating a high-energy diet for 6 weeks were divided into three groups: sham-operated (SO) control, pair-fed (PF) control, and SG group. Six weeks after the surgery, metabolic parameters, SCFA levels in the blood and stool, mRNA and protein expression of SCFA receptors in the ileum and epididymal fat, and gut microbiota were examined.

RESULTS

Metabolic parameters in the SG group were significantly improved compared with the SO group. Acetic acid levels in the blood and stool were significantly higher in the SG group than the PF group. The butyric acid level in the stool was also significantly higher in the SG group than in the PF group. In the ileum and epididymal fat, mRNA and protein expression of GPR41 was significantly higher in the SG group than in the other two groups, and mRNA and protein expression of GPR43 was significantly higher in the SG group than in the PF group. Increases in the genera Enterococcus, Lactobacillus, Lactococcus, and Clostridium were observed in the stool after SG.

CONCLUSIONS

SG may activate SCFA pathways through a change in gut microbiota.

Sodium-glucose co-transporter 1 (SGLT1) differentially regulates gluconeogenesis and GLP-1 receptor (GLP-1R) expression in different diabetic rats: a preliminary validation of the hypothesis of "SGLT1 bridge" as an indication for "surgical diabetes"

BACKGROUND

Sodium-glucose co-transporter 1 (SGLT1) may play a synergistic role in gluconeogenesis (GNG) and glucagon-like peptide-1 (GLP-1) expression. We proposed the hypothesis of a "SGLT1 bridge" as an indication for "surgical diabetes" that was preliminary validated in the present study.

METHODS

We selected nonobese diabetic Goto-Kakizaki (GK) rats and Zuker diabetic fat (ZDF) rats to represent advanced and early diabetes, respectively. Based on glucose gavage with or without SGLT1 inhibitor phlorizin, the rats were divided into 4 groups: Gk-Glu, GK-P, ZDF-Glu, and ZDF-P. The expressions of SGLT1, GLP-1 receptor (GLP-1R), glucose-6 phosphatase (G6Pase), and phosphoenolpyruvate carboxykinase-1 (Pck1) were determined by immunohistochemistry (IHC) or quantitative reverse transcription polymerase chain reaction (RT-qPCR), and the effects of phlorizin were analyzed.

RESULTS

Glucose tolerance was worse in GK rats and the homeostasis model assessment-insulin resistance (HOMA-IR) was higher in ZDF rats, indicating different pathophysiological conditions between the different diabetic rats. GK rats showed higher activity of duodenal SGLT1 (P=0.022) and jejunal SGLT1 mRNA expression (P=0.000) and lower SGLT1 mRNA expression in the liver (P=0.000) and pancreas (P=0.000). Phlorizin effectively inhibited the activity of duodenal SGLT1 in both GK rats (P=0.000) and ZDF rats (P=0.000). In ZDF rats, the expression of GLP-1R mRNA was downregulated in the jejunum (P=0.001) and upregulated in the pancreas (P=0.021) by phlorizin, but there were no regulatory effects on GLP-1R mRNA in the jejunum and pancreas of GK rats. As for the regulatory effects on GNG, phlorizin upregulated Pck1 mRNA in the duodenum (P=0.000) and the jejunum (P=0.038), whereas it downregulated hepatic G6Pase mRNA in ZDF rats (P=0.005) and Pck1 mRNA expression in GK rats (P=0.001), suggesting that SGLT1 inhibitor may have upregulated intestinal GNG in ZDF rats and downregulated hepatic GNG in both ZDF and GK rats.

CONCLUSIONS

SGLT1 showed synergistic regulatory effects on the entero-insular axis (EIA) and the gut-brain-liver axis (GBLA), preliminarily validating the hypothesis of a "SGLT1 bridge". The distinct expression of SGLT1 and its differentially regulatory effects on diabetic rats with different pathophysiological conditions may provide probable potential indications involved in the "Surgical Diabetes" that is supposed as the inclusion for diabetic surgery.

Role of Proximal Intestinal Glucose Sensing and Metabolism in the Blood Glucose Control in Type 2 Diabetic Rats After Duodenal Jejunal Bypass Surgery

BACKGROUND

Although gastric surgery can significantly improve blood glucose homeostasis in type 2 diabetes mellitus (T2DM), its mechanism remains unclear. This study evaluated the role of intestinal glucose sensing, glucose transport, and metabolism in the alimentary limb (A limb) of T2DM rats after duodenal jejunal bypass (DJB) surgery.

METHODS

A T2DM rat model was induced via a high-glucose high-fat diet and low-dose streptozotocin injection. The diabetic rats were divided into two groups: the DJB surgery (T2DM-DJB) group and the sham surgery (T2DM-Sham) group. Wistar rats were used as wild-type control (Control). Small animal PET was used to assess the change in glucose metabolic status in the intestine. The intestinal villi height and the number of EECs after DJB were evaluated. The expressions of sweet taste receptors (T1R2/T1R3), glucose transporters (SGLT1/GLUT2), and key enzymes involved in glucose metabolism (HK2, PFK2, PKM2, G6Pase, and PCK1) in the A limb after DJB was detected by Western blot and qRT-PCR.

RESULTS

Small animal PET analysis showed the intestinal glucose metabolism increased significantly 6 weeks after DJB surgery. The intestinal villi height and the number of EECs in the A limb 6 weeks after surgery increased significantly in T2DM-DJB rats comparing to T2DM-Sham rats. The mRNA and protein expression of T1R1/T1R3 and SGLT1/GLUT2 were downregulated in DJB-T2DM rats, while enzymes involved in glucose metabolism was upregulated in the A limb in T2DM-DJB rats.

CONCLUSION

Proximal intestinal glucose sensing and metabolism play an important role in blood glucose homeostasis by DJB.

Single-Anastomosis Duodenal Switch: Conceptual Difference between East and West

Single-anastomosis duodenal switch (SADS) has become increasingly popular. This review compared the conceptual difference between Eastern (SADS-E) and Western (SADS-W) countries. After searching for SADS through PubMed and high-impact journals, 19 articles with 2280 patients were included for analysis. We found SADS-W was reserved for patients with a high body mass index (BMI) without type 2 diabetes mellitus (T2DM). Surgeons performing SADS-W used larger bougies and preferred shorter common channels. However, SADS-E was mainly preferred in T2DM patients with a low BMI. SADS-E bypassed less bowel and used smaller bougies. The spectra of major postoperative complications, nutritional deficiencies, and gastrointestinal disorders were different between SADS-E and SADS-W. SADS-W yielded better weight loss and better T2DM remission than SADS-E. SADS are effective bariatric and metabolic procedures with promising therapeutic outcomes and acceptable safety.