The entire small intestine mediates the changes in glucose homeostasis after intestinal surgery in Goto-Kakizaki rats. Ann Surg. 2012;256:1049-1058. [PMID: 23001083 DOI: 10.1097/sla.0b013e31826c3866]

Duodenal-jejunal bypass increases intraduodenal bile acids and upregulates duodenal SIRT1 expression in high-fat diet and streptozotocin-induced diabetic rats

BACKGROUND

The mechanisms underlying diabetes remission after duodenal-jejunal bypass (DJB) remain elusive. In DJB surgery, the duodenum is excluded. However, the duodenum has emerged as an important regulator of glucose homeostasis, and elevated duodenal SIRT1 leads to improved hepatic insulin sensitivity. After DJB, bile acids (BAs) in the duodenum are not mixed and diluted by the ingested food. And activation of BA receptors promotes SIRT1 expression in many tissues. We hypothesized that BA-mediated upregulation of SIRT1 may contribute to diabetic control after DJB.

AIM

To investigate the surgical effects of DJB on duodenal SIRT1 expression and uncover the potential crosslinks between BAs and SIRT1.

METHODS

Twenty diabetic rats were randomly allocated to the sham (n = 10) and DJB (n = 10) groups. Body weight, food intake, fasting blood glucose (FBG), serum and intraduodenal total BA (TBA) levels were measured accordingly. Oral glucose tolerance test (OGTT) and intraperitoneal pyruvate tolerance test (ipPTT) were performed to evaluate the effects of surgeries on systemic glucose disposal and hepatic gluconeogenesis. The key genes of BA signaling pathway in the duodenal mucosa, including farnesoid X receptor (FXR), small heterodimer partner (SHP), and Takeda G-protein-coupled receptor 5 (TGR5) were evaluated by real-time quantitative polymerase chain reaction 8 wk postoperatively. The duodenal SIRT1, AMPK, and phosphorylated AMPK (p-AMPK) levels were evaluated by western blotting. Rat small intestine epithelial IEC-6 cells were treated with GW4064 and INT-777 to verify the effects of BAs on SIRT1 expression in enterocytes.

RESULTS

The DJB group exhibited body weight and food intake comparable to those of the sham group at all postoperative time points. The FBG level and area under the curve for the OGTT and ipPTT were significantly lower in the DJB group. The DJB group exhibited higher fasting and postprandial serum TBA levels than the sham group at both 2 and 8 wk postoperatively. At 8 wk after surgery, the DJB group showed higher intraluminal TBA concentration, upregulated mRNA expression of FXR and SHP, and elevated protein expression of SIRT1 and p-AMPK in the descending and horizontal segments of the duodenum. Activation of FXR and TGR5 receptors by GW4064 and INT-777 increased the mRNA and protein expression of SIRT1 and promoted the phosphorylation of AMPK in IEC-6 cells.

CONCLUSION

DJB elevates intraduodenal BA levels and activates the duodenal BA signaling pathway, which may upregulate duodenal SIRT1 and further contribute to improved glucose homeostasis after DJB.

Central GLP-1 contributes to improved cognitive function and brain glucose uptake after duodenum-jejunum bypass on obese and diabetic rats

The improvement of cognitive function following bariatric surgery has been highlighted, yet its underlying mechanisms remain elusive. Finding the improved brain glucose uptake of patients after Roux-en-Y gastric bypass (RYGB), duodenum-jejunum bypass (DJB), and sham surgery (Sham) were performed on obese and diabetic Wistar rats, and intracerebroventricular (ICV) injection of glucagon-like peptide-1 (GLP-1) analog liraglutide (Lira), antagonist exendin-(9-39) (Exe-9), and the viral-mediated GLP-1 receptor (Glp-1r) knockdown (KD) were applied on both groups to elucidate the role of GLP-1 in mediating cognitive function and brain glucose uptake assessed with the Morris water maze (MWM) and positron emission tomography (PET). Insulin and GLP-1 in serum and cerebral spinal fluid (CSF) were measured, and the expression of glucose uptake-related proteins including glucose transporter 1 (GLUT-1), GLUT-4, phospho-Akt substrate of 160kDa (pAS160), AS160, Rab10, Myosin-Va as well as the c-fos marker in the brain were examined. Along with augmented glucose homeostasis following DJB, central GLP-1 was correlated with the improved cognitive function and ameliorated brain glucose uptake, which was further confirmed by the enhancive role of Lira on both groups whereas the Exe-9 and Glp-1r KD were opposite. Known to activate insulin-signaling pathways, central GLP-1 contributes to improved cognitive function and brain glucose uptake after DJB.NEW & NOTEWORTHY The improvement of cognitive function following bariatric surgery has been highlighted while its mechanisms remain elusive. The brain glucose uptake of patients was improved after RYGB, and the DJB and sham surgery performed on obese and diabetic Wistar rats revealed that the elevated central GLP-1 contributes to the dramatic improvement of cognitive function, brain glucose uptake, transport, glucose sensing, and neuronal activation.

The Mid-Term Effects of Transit Bipartition with Sleeve Gastrectomy on Glycemic Control, Weight Loss, and Nutritional Status in Patients with Type 2 Diabetes Mellitus: a Retrospective Analysis of a 3-Year Follow-up

BACKGROUND

Metabolic surgery is an effective treatment method for glycemic control and weight loss in obese patients with type 2 diabetes mellitus (T2DM). This study aimed to present the mid-term metabolic effects and weight loss results of the patients with T2DM who underwent transit bipartition with sleeve gastrectomy (TB-SG).

METHODS

A total of 32 obese patients with T2DM who underwent TB-SG were included in the study. The T2DM remission status after surgery was evaluated. The postoperative glycemic variables, weight loss, lipid profile, and nutritional profile were also compared with the baseline values.

RESULTS

At 36 months after surgery, T2DM remission occurred in 27 patients (84.3%) and the mean BMI decreased from 44.70 ± 9.34 to 29.75 ± 2.19 kg/m². The percentage of total weight loss (TWL) and excess weight loss (EWL) was 33.84% and 77.19%, respectively. The mean LDL values significantly decreased compared to baseline; however, the mean HDL did not significantly differ. No significant difference was observed regarding the mean albumin, vitamin B12, and folic acid levels.

CONCLUSION

TB-SG procedure seems promising in terms of T2DM remission and weight loss with less malnutrition and vitamin deficiency in treating obese patients with T2DM.

Preoperative predictors of early relapse/no-remission of type-2 diabetes after metabolic surgery in Chinese patients

Remission of type 2 diabetes mellitus (T2DM) after metabolic surgery in some patients is not sustained. There is limited data regarding the preoperative factors predicting early relapse of T2DM in Chinese patients. The objective of this study is to look for preoperative predictors of early T2DM relapse/no remission in patients with obesity and diabetes who underwent Roux-en-Y gastric bypass (RYGB) or loop duodeno-jejunal bypass with sleeve gastrectomy (LDJB-SG). This is a retrospective study of 113 patients who underwent RYGB or LDJB-SG for T2DM. All T2DM patients with BMI 27.5 to 37.5 kg/m² , having uncontrolled diabetes and T2DM patients with BMI > 37.5 were included in the study. A multivariate analysis with a logistic regression model was used for analysed factors. Nineteen patients (16.8%) had early relapse and 12 (10.6%) did not have remission. Mean age of patients was significantly more who relapsed/no-remission (44.9 vs 40.3 years). On univariate analysis, base line weight (86 vs 96.7 kg) was significantly lower in patients who relapsed/no-remission. Patients with sustained remission had statistically significant low glycosylated haemoglobin (P < .030), plasma glucose (120 minutes) (P < .002) on OGTT, area under curve glucose (P < .011) values and more C-peptide (P < .006) on univariate analysis. Only duration of diabetes (OR 2.78, 95% CI 1.56-4.97, P < .001) was found to be independent preoperative factor associated with early relapse/no-remission. Two years of diabetes duration was the cut-off point to predict relapse/no-remission (sensitivity 78.9, specificity 63.4, receiver operating characteristic curve 0.71). Duration of diabetes is the most probable, independent preoperative predictor of early T2DM relapse/no-remission in patient with obesity and diabetes undergoing metabolic surgery.

Restoration of myocardial glucose uptake with facilitated myocardial glucose transporter 4 translocation contributes to alleviation of diabetic cardiomyopathy in rats after duodenal-jejunal bypass

AIMS/INTRODUCTION

Duodenal-jejunal bypass (DJB) surgery has been reported to effectively relieve diabetic cardiomyopathy (DCM). However, the specific mechanisms remain largely unknown. The present study was designed to determine the alterations of myocardial glucose uptake (MGU) after DJB and their effects on DCM.

MATERIALS AND METHODS

Duodenal-jejunal bypass and sham surgeries were carried out in diabetic rats induced by a high-fat diet and a low dose of streptozotocin, with chow-diet fed rats as controls. Bodyweight, food intake, glucose homeostasis and lipid profiles were measured at indicated time-points. Cardiac function was evaluated by transthoracic echocardiography and hemodynamic measurement. Cardiac remodeling was assessed by a series of morphometric analyses along with transmission electron microscopy. Positron-emission tomography with fluorine-18 labeled fluorodeoxyglucose was carried out to evaluate the MGU in vivo. Furthermore, myocardial glucose transporters (GLUT; GLUT1 and GLUT4), myocardial insulin signaling and GLUT-4 translocation-related proteins were investigated to elucidate the underlying mechanisms.

RESULTS

The DJB group showed restored systolic and diastolic cardiac function, along with significant remission in cardiac hypertrophy, cardiac fibrosis, lipid deposit and ultrastructural disorder independent of weight loss compared with the sham group. Furthermore, the DJB group showed upregulated myocardial insulin signaling, hyperphosphorylation of AKT substrate of 160 kDa (AS160) and TBC1D1, along with preserved soluble N-ethylmaleimide-sensitive factor attachment protein receptor proteins, facilitating the GLUT-4 translocation to the myocardial cell surface and restoration of MGU.

CONCLUSIONS

The present findings provide evidence that restoration of MGU is implicated in the alleviation of DCM after DJB through facilitating GLUT-4 translocation, suggesting a potential choice for treatment of human DCM if properly implemented.

Facilitated Ca2+ homeostasis and attenuated myocardial autophagy contribute to alleviation of diabetic cardiomyopathy after bariatric surgery

Bariatric surgery has been reported to relieve diabetic cardiomyopathy (DCM) effectively. However, the mechanisms remain largely unknown. To determine the effects of bariatric surgery on DCM via modulation of myocardial Ca²⁺ homeostasis and autophagy, sleeve gastrectomy (SG), duodenal-jejunal bypass (DJB), and sham surgeries were performed in diabetic rats induced by high-fat diet and a low dose of streptozotocin. Cardiac remodeling was assessed by a series of morphometric and histological analyses. Transthoracic echocardiography and hemodynamic measurements were performed to determine cardiac function. Ca²⁺ homeostasis was evaluated by measuring Ca²⁺ transients with fura-2 AM in isolated ventricular myocytes along with detection of the abundance of Ca²⁺ regulatory proteins in the myocardium. Myocardial autophagic flux was determined by expression of autophagy-related proteins in the absence and presence of chloroquine. Both SG and DJB surgery alleviated DCM morphologically and functionally. Ca²⁺ transients exhibited a significantly higher amplitude and faster decay after SG and DJB, which could be partially explained by increased expression of ryanodine receptor 2, sarco(endo)plasmic reticulum Ca²⁺-2ATPase, 12.6-kDa FK506-binding protein, and hyperphosphorylation of phospholamban. In addition, a lower level of light chain 3B and higher level of p62 were detected after both SG and DJB, which was not reversed by chloroquine treatment and associated with activated mammalian target of rapamycin and attenuated AMP-activated protein kinase signaling pathway. Collectively, these results provided evidence that bariatric surgery could alleviate DCM effectively, which may result, at least in part, from facilitated Ca²⁺ homeostasis and attenuated autophagy, suggesting a potential choice for treatment of DCM when properly implemented. NEW & NOTEWORTHY The present study is the first to investigate the modulation of myocardial Ca²⁺ homeostasis and autophagy after bariatric surgery and to examine its effects on diabetic cardiomyopathy. Bariatric surgery could facilitate myocardial Ca²⁺ homeostasis and attenuate myocardial autophagy, contributing to the alleviation of cardiomyopathy morphologically and functionally in a diabetic rat model.

Deactivation of the NLRP3 inflammasome in infiltrating macrophages by duodenal-jejunal bypass surgery mediates improvement of beta cell function in type 2 diabetes

OBJECTIVE

Bariatric surgery could improve pancreatic beta cell function, thereby leading to the remission of the type 2 diabetes mellitus (T2DM). However, the specific mechanism underlying this phenomenon is yet to be revealed. The aim of this study is to test the hypothesis that Nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome in infiltrating macrophages plays an important role in the modulation of beta cell function after duodenal-jejunal bypass (DJB) surgery.

METHODS

DJB and sham surgery were performed in diabetic Sprague-Dawley (SD) rats induced by high-fat diet (HFD) and streptozotocin (STZ). Body weight, food intake, and glucose tolerance test (GTT) were measured at indicated time points. Apoptosis of the beta cells was measured by Terminal deoxynucleotidyl transferase mediated dUTP Nick End Labeling (TUNEL) assay. We also assessed the macrophage content and NLRP3 expression in the rat model. Furthermore, macrophage reconstitution was performed after DJB surgery. Beta cell function and NLRP3 inflammasome pathway were re-evaluated in wild-type macrophage reconstitution group and NLRP3-knockdown macrophage reconstitution group.

RESULTS

DJB surgery group rats displayed rapid and sustained improvement in glucose tolerance. Decreased apoptosis and improved secretion function of the beta cells were observed in DJB surgery group. NLRP3 inflammasome pathway in infiltrating macrophages was also suppressed after DJB surgery. Moreover, diabetic remission acquired by DJB sustained in NLRP3-knockdown macrophage reconstitution group, while extinguished in group reconstituted with wild-type macrophage.

CONCLUSIONS

NLRP3 inflammasome deactivation in infiltrating macrophages is involved in marked beta cell function improvement after DJB surgery.

Effects of Bariatric Surgery on Serum Bile Acid Composition and Conjugation in a Diabetic Rat Model

BACKGROUND

Serum bile acids (BAs) are elevated following bariatric surgery and have emerged as a potential glucose-lowering beneficial factor. 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 diabetic rat model.

METHODS

Duodenal-jejunal bypass (DJB), sleeve gastrectomy (SG), and sham operation were performed in diabetic rats induced by high-fat diet (HFD) and streptozotocin (STZ). 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 7α hydroxylase (CYP7A1), bile acid: CoA synthase (BACS) and bile acid-CoA: amino acid N-acyltransferase (BAAT) at both transcriptional and protein levels in the liver were evaluated at 12 weeks postoperatively.

RESULTS

Compared with sham group, DJB and SG both achieved rapid and sustained improvements in glucose tolerance and insulin sensitivity. They also resulted in increased serum BAs, especially the taurine-conjugated BAs by elevated conjugation. No obvious difference was detected between DJB and SG except that SG achieved decreased weight gain and food intake.

CONCLUSIONS

The preferentially elevated serum taurine-conjugated BAs were similar after different bariatric surgeries, and the enhanced conjugation of BAs in the liver might account for the changed serum BAs profiles.

Diabetes recurrence after metabolic surgeries correlates with re-impaired insulin sensitivity rather than beta-cell function

AIM

To investigate factors causing diabetes recurrence after sleeve gastrectomy (SG) and duodenal-jejunal bypass (DJB).

METHODS

SG and DJB were performed on rats with diabetes induced by high-fat diet (HFD) and streptozotocin (STZ). HFD was used to induce diabetes recurrence at 4 wk postoperatively. Body weight, oral glucose tolerance test, homeostatic model assessment of insulin resistance (HOMA-IR), insulin signaling [IR, insulin receptor substrate (IRS)1, IRS2, phosphatidylinositol 3-kinase and AKT in liver and skeletal muscle], oral glucose stimulated insulin secretion, beta-cell morphology (mass, apoptosis and insulin secretion), glucagon-like peptide (GLP)-1, PYY and ghrelin were compared among SG rats with common low-fat diet (SG-LFD), SG with HFD (SG-HFD), DJB rats with LFD (DJB-LFD), DJB with HFD (DJB-HFD) and sham-operation with LFD (Sham) at targeted postoperative times.

RESULTS

SG and DJB resulted in significant improvement in glucose tolerance, lower HOMA-IR, up-regulated hepatic and muscular insulin signaling, higher levels of oral glucose-stimulated insulin secretion, bigger beta-cell mass, higher immunofluorescence intensity of insulin, fewer transferase-mediated dUTP-biotin 3’ nick end-labeling (TUNEL)-positive beta cells and higher postprandial GLP-1 and PYY levels than in the Sham group. The improvement in glucose tolerance was reversed at 12 wk postoperatively. Compared with the SG-LFD and DJB-LFD groups, the SG-HFD and DJB-HFD groups showed higher HOMA-IR, down-regulated hepatic and muscular insulin signaling, and more TUNEL-positive beta cells. No significant difference was detected between HFD and LFD groups for body weight, glucose-stimulated insulin secretion, beta-cell mass, immunofluorescence intensity of insulin, and postprandial GLP-1 and PYY levels. Fasting serum ghrelin decreased in SG groups, and there was no difference between HFD-SG and LFD-SG groups.

CONCLUSION

HFD reverses the improvement in glucose homeostasis after SG and DJB. Diabetes recurrence may correlate with re-impaired insulin sensitivity, but not with alterations of beta-cell function and body weight.

Targeting the gastrointestinal tract to treat type 2 diabetes

The rising global rates of type 2 diabetes and obesity present a significant economic and social burden, underscoring the importance for effective and safe therapeutic options. The success of glucagon-like-peptide-1 receptor agonists in the treatment of type 2 diabetes, along with the potent glucose-lowering effects of bariatric surgery, highlight the gastrointestinal tract as a potential target for diabetes treatment. Furthermore, recent evidence suggests that the gut plays a prominent role in the ability of metformin to lower glucose levels. As such, the current review highlights some of the current and potential pathways in the gut that could be targeted to improve glucose homeostasis, such as changes in nutrient sensing, gut peptides, gut microbiota and bile acids. A better understanding of these pathways will lay the groundwork for novel gut-targeted antidiabetic therapies, some of which have already shown initial promise.

Duodenal-jejunal bypass attenuates progressive failure of pancreatic islets in streptozotocin-induced diabetic rats

BACKGROUND

Preservation of pancreatic beta cell function has been increasingly appealing in the treatment of type 2 diabetes. Evidence is still limited on how bariatric surgery affects pancreatic beta cell apoptosis.

SETTING

University medical center.

OBJECTIVE

The study aimed to investigate the effect of a major component of Roux-en-Y gastric bypass, duodenal-jejunal bypass, on protecting pancreatic beta cells from progressive loss.

METHODS

Forty-five normal Sprague-Dawley rats were randomly assigned into 3 groups: duodenal-jejunal bypass (DJB) group (n = 16) and sham (S) group (n = 17), based upon the procedure received, and a control (C) group (n = 12) without any procedure performed, to eliminate potential traumatic effects from surgery. Ten days after surgery, streptozotocin (STZ, 45 mg/kg weight) was injected intraperitoneally into each animal, including the control animals, to selectively induce pancreatic beta cell apoptosis. Weight, food intake, plasma glucose level, and the results of an oral glucose tolerance test were measured before surgery, pre-STZ injection, and up to 4 weeks after STZ injection. Plasma insulin and glucagon-like peptide-1 levels were also assayed during oral glucose tolerance test. At the end, pancreatic tissues were sliced and stained for beta cell analysis.

RESULTS

There were no significant differences in weight among all groups at any time points measured, despite rats in the S and C groups consuming more food than those in the DJB group as measured on day 10 (P<.05) and day 20 (P<.01) after STZ injection. Animals undergoing DJB did not experience symptoms typical of uncompensated diabetes, including hyperphagia and progressive weight loss. After STZ injection, fasting plasma glucose levels in the DJB group were significantly lower than those in the C and S groups (P<.001). When challenged by glucose load, DJB rats also had a better glycemic excursion (P<.01) and incretin response compared with C and S rats (P<.05). In addition, pancreatic beta cell size and mass was better preserved in DJB rats (P< .001).

CONCLUSION

DJB is able to protect pancreatic beta cells from apoptosis, which leads to better glycemic control and delayed onset of diabetes. These results imply the necessity of including a DJB component when designing bariatric procedure to achieve a better long-term outcome.

Effects of sleeve gastrectomy with jejuno-jejunal or jejuno-ileal loop on glycolipid metabolism in diabetic rats

AIM

To explore the effect of sleeve gastrectomy (SG) with jejuno-jejunal or jejuno-ileal loop on glycolipid metabolism in diabetic rats.

METHODS

Diabetic rats, which were induced by high-fat diet (HFD), nicotinamide and low-dose streptozotocin, underwent sham operations, SG, SG with jejuno-ileal loop (SG-JI) and SG with jejuno-jejunal loop (SG-JJ) followed by postoperative HFD. Then, at the time points of baseline and 2, 12 and 24 wk postoperatively, we determined and compared several variables, including the area under the curve for the results of oral glucose tolerance test (AUC_OGTT), serum levels of triglyceride, cholesterol and ghrelin in fasting state, homeostasis model assessment of insulin resistance (HOMA-IR), body weight, calorie intake, glucagon-like peptide (GLP)-1 and insulin secretions after glucose gavage at dose of 1 g/kg.

RESULTS

At 2 wk postoperatively, rats that underwent SG, SG-JJ and SG-JI, compared with sham-operated (SHAM) rats, demonstrated lower body weight, calorie intake and ghrelin (P < 0.05 vs SHAM), enhanced secretion of insulin and GLP-1 after glucose gavage (P < 0.05 vs SHAM), improved AUC_OGTT, HOMA-IR, fasting serum triglyceride and cholesterol (AUC_OGTT: 1616.9 ± 83.2, 837.4 ± 83.7, 874.9 ± 97.2 and 812.6 ± 81.9, P < 0.05 vs SHAM; HOMA-IR: 4.31 ± 0.54, 2.94 ± 0.22, 3.17 ± 0.37 and 3.41 ± 0.22, P < 0.05 vs SHAM; Triglyceride: 2.35 ± 0.17, 1.87 ± 0.23, 1.98 ± 0.30 and 2.04 ± 0.21 mmol/L, P < 0.05 vs SHAM; Cholesterol: 1.84 ± 0.21, 1.53 ± 0.20, 1.52 ± 0.20 and 1.46 ± 0.23 mmol/L). At 12 wk postoperatively, rats receiving SG-JJ and SG-JI had lower body weight, reduced levels of triglyceride and cholesterol and elevated level of GLP-1 compared to those receiving SG (P < 0.05 vs SG). At 24 wk after surgery, compared with SG, the advantage of SG-JJ and SG-JI for glucolipid metabolism was still evident (P < 0.05 vs SG). SG-JI had a better performance in lipid metabolism and GLP-1 secretion of rats than did SG-JJ.

CONCLUSION

SG combined with intestinal loop induces better glycolipid metabolism than simple SG, with the lipid metabolism being more improved with SG-JI compared to SG-JJ.

Alterations in gut microbiota during remission and recurrence of diabetes after duodenal-jejunal bypass in rats

AIM: To observe the alterations in gut microbiota in high-fat diet (HFD)-induced diabetes recurrence after duodenal-jejunal bypass (DJB) in rats.

METHODS: We assigned HDF- and low-dose streptozotocin-induced diabetic rats into two major groups to receive DJB and sham operation respectively. When the DJB was completed, we used HFD to induce diabetes recurrence. Then, we grouped the DJB-operated rats by blood glucose level into the DJB-remission (DJB-RM) group and the DJB-recurrence (DJB-RC) group. At a sequence of time points after operations, we compared calorie content in the food intake (calorie intake), oral glucose tolerance test, homeostasis model assessment of insulin resistance (HOMA-IR), concentrations of glucagon-like peptide 1 (GLP-1), serum insulin, total bile acids (TBAs) and lipopolysaccharide (LPS) and alterations in colonic microbiota.

RESULTS: The relative abundance of Firmicutes in the control (58.06% ± 11.12%; P < 0.05 vs sham; P < 0.05 vs DJB-RC) and DJB-RM (55.58% ± 6.16%; P < 0.05 vs sham; P < 0.05 vs DJB-RC) groups was higher than that in the sham (29.04% ± 1.36%) and DJB-RC (27.44% ± 2.17%) groups; but the relative abundance of Bacteroidetes was lower (control group: 33.46% ± 10.52%, P < 0.05 vs sham 46.88% ± 2.34%, P < 0.05 vs DJB-RC 47.41% ± 5.67%. DJB-RM group: 34.63% ± 3.37%, P < 0.05 vs sham; P < 0.05 vs DJB-RC). Escherichia coli was higher in the sham (15.72% ± 1.67%, P < 0.05 vs control, P < 0.05 vs DJB-RM) and DJB-RC (16.42% ± 3.00%; P < 0.05 vs control; P < 0.05 vs DJB-RM) groups than in the control (3.58% ± 3.67%) and DJB-RM (4.15% ± 2.76%) groups. Improved HOMA-IR (2.82 ± 0.73, P < 0.05 vs DJB-RC 4.23 ± 0.72), increased TBAs (27803.17 ± 4673.42 ng/mL; P < 0.05 vs DJB-RC 18744.00 ± 3047.26 ng/mL) and decreased LPS (0.12 ± 0.04 ng/mL, P < 0.05 vs DJB-RC 0.19 ± 0.03 ng/mL) were observed the in DJB-RM group; however, these improvements were reversed in the DJB-RC group, with the exception of GLP-1 (DJB-RM vs DJB-RC P > 0.05).

CONCLUSION: Alterations in gut microbiota may be responsible for the diabetes remission and recurrence after DJB, possibly by influencing serum LPS and TBAs.

Expedited Biliopancreatic Juice Flow to the Distal Gut Benefits the Diabetes Control After Duodenal-Jejunal Bypass

BACKGROUND

Serum bile acids (BAs) are elevated after metabolic surgeries including Roux-en-Y gastric bypass (RYGB), ileal transposition (IT), and duodenal-jejunal bypass (DJB). Recently, BAs have emerged as a kind of signaling molecules, which can not only promote glucagon-like peptide-1 (GLP-1) secretion but can also regulate multiple enzymes involved in glucose metabolism. The aim of this study was to investigate whether expedited biliopancreatic juice flow to the distal gut contributes to the increased serum GLP-1 and BAs and benefits the diabetes control after DJB.

METHODS

DJB, long alimentary limb DJB (LDJB), duodenal-jejunal anastomosis (DJA), and sham operation were performed in diabetic rats induced by high-fat diet (HFD) and low dose of streptozotocin (STZ). Body weight, food intake, oral glucose tolerance, insulin tolerance, glucose-stimulated insulin and GLP-1 secretion, fasting serum total bile acids (TBAs), and lipid profiles were measured at indicated time points.

RESULTS

Compared with sham operation, DJA, DJB, and LDJB all achieved rapid and dramatic improvements in glucose tolerance and insulin sensitivity independently of food restriction and weight loss. DJB and LDJB-operated rats exhibited even better glucose tolerance, higher fasting serum TBAs, and higher glucose-stimulated GLP-1 secretion than the DJA group postoperatively. No difference was detected in insulin sensitivity and glucose-stimulated insulin secretion between DJA, DJB, and LDJB groups.

CONCLUSIONS

Expedited biliopancreatic juice flow to the distal gut was associated with augmented GLP-1 secretion and increased fasting serum TBA concentration, which may partly explain the metabolic benefits of DJB.

In Vivo Models for Incretin Research: From the Intestine to the Whole Body

Incretin hormones are produced by enteroendocrine cells (EECs) in the intestine in response to ingested nutrient stimuli. The incretin effect is defined as the difference in the insulin secretory response between the oral glucose tolerance test and an isoglycemic intravenous glucose infusion study. The pathophysiology of the decreased incretin effect has been studied as decreased incretin sensitivity and/or β-cell dysfunction per se. Interestingly, robust increases in endogenous incretin secretion have been observed in many types of metabolic/bariatric surgery. Therefore, metabolic/bariatric surgery has been extensively studied for incretin physiology, not only the hormones themselves but also alterations in EECs distribution and genetic expression levels of gut hormones. These efforts have given us an enormous understanding of incretin biology from synthesis to in vivo behavior. Further innovative studies are needed to determine the mechanisms and targets of incretin hormones.

Duodenal-jejunal bypass surgery suppresses hepatic de novo lipogenesis and alleviates liver fat accumulation in a diabetic rat model

BACKGROUND

Duodenal-jejunal bypass (DJB) surgery can induce rapid and durable remission of type 2 diabetes mellitus (T2DM), but the intrinsic mechanisms remain to be elucidated. Recent studies indicated that improved hepatic insulin resistance and insulin signaling transduction might contribute to the diabetic control after DJB. Given the important role of liver adiposity in hepatic insulin resistance, this study was aimed at investigating the effects of DJB on glucose homeostasis and liver fat accumulation in a T2DM rat model induced by high-fat diet (HFD) and small dose of streptozotocin (STZ).

METHODS

Forty adult male diabetic rats induced by HFD and small dose of STZ were randomly assigned to sham and DJB groups. Body weight, calorie intake, hormone levels, glucose, and lipid parameters were measured at indicated time points. Subsequently, hepatic triglycerides (TG) content and the protein levels of sterol regulatory element binding protein-1 (SREBP-1), carbohydrate response element binding protein (ChREBP), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC) were evaluated at 2 and 8 weeks postoperatively.

RESULTS

Compared with sham group, DJB induced rapid and significant improvements in glucose homeostasis and insulin sensitivity independently of weight loss and calorie restriction. The DJB-operated rats exhibited lower liver TG content and decreased hepatic SREBP-1, ChREBP, ACC, and FAS at 8 weeks postoperatively.

CONCLUSIONS

DJB alleviated hepatic fat accumulation and downregulated the key transcriptional regulators and enzymes involved in hepatic de novo lipogenesis, which might contribute to improved hepatic insulin sensitivity and glucose homeostasis after DJB.

Glucoregulatory Relevance of Small Intestinal Nutrient Sensing in Physiology, Bariatric Surgery, and Pharmacology

Emerging evidence suggests the gastrointestinal tract plays an important glucoregulatory role. In this perspective, we first review how the intestine senses ingested nutrients, initiating crucial negative feedback mechanisms through a gut-brain neuronal axis to regulate glycemia, mainly via reduction in hepatic glucose production. We then highlight how intestinal energy sensory mechanisms are responsible for the glucose-lowering effects of bariatric surgery, specifically duodenal-jejunal bypass, and the antidiabetic agents metformin and resveratrol. A better understanding of these pathways lays the groundwork for intestinally targeted drug therapy for the treatment of diabetes.

Metabolic surgery and intestinal gene expression: Digestive tract and diabetes evolution considerations

AIM: To investigate the effects of bariatric surgery on metabolic parameters, incretin hormone secretion, and duodenal and ileal mucosal gene expression.

METHODS: Nine patients with type 2 diabetes mellitus (T2DM), chronic serum hyperglycemia for more than 2 years, and a body mass index (BMI) of 30-35 kg/m² underwent metabolic surgery sleeve gastrectomy with transit bipartition between May 2011 and December 2011. Blood samples were collected pre and 3, 6 and 12 mo postsurgery. Duodenal and ileal mucosa samples were collected pre- and 3 mo postsurgery. Pre- and postoperative blood samples were collected in the fasting state before ingestion of a standard meal (520 kcal) and again 30, 60, 90, and 120 min after the meal to determine hemoglobin A_1c (HbA_1c) levels and the lipid profile, which consisted of triglyceride and total cholesterol levels. Intestinal gene expression of p53 and transforming growth factor (TGF)-β was analyzed using quantitative reverse-transcription PCR. Gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) were quantified using the enzyme-linked immunoassay method and analyzed pre- and postoperatively. Student’s t test or repeated measurements analysis of variance with Bonferroni corrections were performed as appropriate.

RESULTS: BMI values decreased by 15.7% within the initial 3 mo after surgery (31.29 ± 0.73 vs 26.398 ± 0.68, P < 0.05) and then stabilized at 22% at 6 mo postoperative, resulting in similar values 12 mo postoperatively (20-25 kg/m²). All of the patients experienced improved T2DM, with 7 patients (78%) achieving complete remission (HbA_1c < 6.5%), and 2 patients (22%) achieving improved diabetes (HbA_1c < 7.0% with or without the use of oral hypoglycemic agents). At 3 mo postoperatively, fasting plasma glucose had also decreased (59%) (269.55 ± 18.24 mg/dL vs 100.77 ± 3.13 mg/dL, P < 0.05) with no further significant changes at 6 or 12 mo postoperatively. In the first month postoperatively, there was a complete withdrawal of hypoglycemic medications in all patients, who were taking at least 2 hypoglycemic drugs preoperatively. GLP-1 levels significantly increased after surgery (149.96 ± 31.25 vs 220.23 ± 27.55) (P < 0.05), while GIP levels decreased but not significantly. p53 gene expression significantly increased in the duodenal mucosa (P < 0.05, 2.06 fold) whereas the tumor growth factor-β gene expression significantly increased (P < 0.05, 2.52 fold) in the ileal mucosa after surgery.

CONCLUSION: Metabolic surgery ameliorated diabetes in all of the patients, accompanied by increased anti-proliferative intestinal gene expression in non-excluded segments of the intestine.

Duodeno-jejunal tube placement in an experimental model of obesity: effects on food behaviour and basal energy expenditure

BACKGROUND

Metabolic surgery can modulate weight as well as food intake and basal energy expenditure. In this study, we evaluate the effectiveness of duodenal exclusion by analysing anthropometric results, intake variations, food behaviour and calorimetric parameters.

METHODS

This is an experimental study with 8-week-old Sprague-Dawley male rats. The sequences used are as follows: Cafeteria diet for 3 weeks, followed by surgery and sacrifice at 4 weeks. Four experimental groups are as follows: two non-obese groups (n = 15; surgery = 10, sham = 5) and two obese groups by cafeteria diet (n = 15; surgery = 10, sham = 5). Surgery performed was duodenal exclusion with physical barrier. Weight, intake, glycaemia and basal energy expenditure by indirect calorimetry were monitored before and after surgery.

RESULTS

Weight changes in groups that underwent intervention were significant. The reduction in calorie consumption after surgery was significant in the obese intervention group despite an increased standard feed consumption (161 ± 11 vs 139 ± 13 Kcal/day, p < 0.05; due to a lower consumption of cafeteria diet). In non-obese animals, changes were transient. Basal energy expenditure decreased in both intervention groups: 6.2 ± 0.5 vs 5.5 ± 0.4 Kcal/kg/h in non-obese animals and 5.6 ± 0.3 vs 4.7 ± 0.3 Kcal/kg/h in obese animals (p < 0.05).

CONCLUSIONS

Duodeno-jejunal tube placement stops weight gain in obese and non-obese animals. In obese animals, there is an important qualitative change in appetite towards standard feed with a significant decrease in caloric intake. In non-obese animals, changes in quantitative intake are transient. This surgery decreases basal energy expenditure in obese animals. This may be attributed to an enhanced thermogenic effect of food and a slowing in the animal's weight gain.

Renal function is ameliorated in a diabetic nephropathy rat model through a duodenal-jejunal bypass

AIMS

Diabetes surgery is growing in popularity and has been shown to have marked effects on diabetes. However, several studies have shown it may induce some renal injury, and, currently, the impact of diabetes surgery on renal function is unclear. In this study, we examined renal function and histological changes in rats with diabetic nephropathy (DN) following a duodeno-jejunal bypass (DJB) operation.

METHODS

Rats with streptozotocin (STZ)-induced diabetes were randomly assigned to 3 groups: DJB group (DJB), Sham-DJB group (S-DJB) and diabetes group (DM). Six age-matched normal rats were assigned as the control group. DJB and sham surgery were performed. Body weight, food intake, glucose levels, lipid parameters, cystatin C (Cys_C) levels, serum and urinary creatinine, 24h urine albumin excretion rate (UAER) and glomerular filtration rate (GFR) were measured. Histological analysis and immunohistochemical studies of renal sections were also performed.

RESULTS

DJB ameliorated renal function by improving UAER, GFR and Cys_C levels 4 and 8 weeks after surgery. It also improved lipid metabolism by decreasing fasting total serum cholesterol (TC) and triglyceride (TG) levels. Immuno-staining of synaptopodin showed podocyte injury was also improved in DJB glomeruli compared with sham and DM groups. Histological analysis showed that the mesangial expansion was not significantly prevented 8 weeks after DJB surgery.

CONCLUSION

DJB ameliorated renal function in UAER and GFR but not mesangial expansion in a DN rat model. The improvement of renal function may be attributed to reversing the injury or loss of podocytes after DJB surgery.

Enteroendocrine secretion of gut hormones in diabetes, obesity and after bariatric surgery

Gastric bypass surgery is associated with a major weight loss and often causes remission in patients with type 2 diabetes. Surgery is also associated with dramatic increases in the secretion of the gut hormones, glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), both of which regulate appetite and food intake, while GLP-1 in addition functions as an incretin hormone, stimulating insulin secretion. It has been possible to probe the role of GLP-1 for the diabetes resolution after gastric bypass using a GLP-1 receptor antagonist, and it is clear that the enhanced beta cell sensitivity to glucose which underlies the enhanced insulin secretion in the patients after the operation depends critically on the increased GLP-1 secretion. Both hormones seem to contribute importantly to the reduction in food intake after bypass and, therefore, to the weight loss. Currently, there are no data to indicate that decreased secretion of the hormones is involved in the pathogenesis of obesity and/or diabetes, but impaired secretion generally observed in obesity (and hence also in diabetes) may contribute to the development. Because of these effects receptor agonists for both hormones are currently being developed for the treatment of obesity and diabetes.