Effects of duodeno-jejunal bypass on glucose metabolism in obese rats with type 2 diabetes

The role of weight control in the management of type 2 diabetes mellitus: Bariatric surgery

Diabetes mellitus is one of the major epidemics in the United States. It is heavily associated with obesity and multiple metabolic derangements that lead to long term morbidity, mortality as well as financial burden. Although medical therapy has been the mainstay in the management of diabetes mellitus, there remains a large portion of this patient population which struggles to obtain adequate glycemic control and long-term weight control with medical management alone. Bariatric surgery is a powerful tool in combating diabetes mellitus and affects glucose homeostasis through a variety of pathways. While it does provide a durable pathway for weight loss, improvement in glucose homeostasis is not only affected by the weight loss seen after bariatric surgery. Changes in gut hormone secretion, insulin regulation, and gut microbial composition also affect how these operations improve glucose homeostasis. Through improvement in the management of diabetes mellitus, comorbidities including cardiovascular disease, in turn demonstrate improvement. In this article, we will discuss the role of bariatric (metabolic) surgery as it relates to long term weight loss and the impact that weight loss has on improvement in diabetes mellitus.

The role of bilio-pancreatic limb in nonalcoholic steatohepatitis improvement after duodenal-jejunal bypass in rats

BACKGROUND

Nonalcoholic fatty liver disease, which is highly associated with obesity, includes nonalcoholic steatohepatitis. Lipopolysaccharides from the intestine would induce inflammation in the liver in nonalcoholic fatty liver disease. This study aimed to examine the role of the bilio-pancreatic limb in the effect of duodenal-jejunal bypass on nonalcoholic steatohepatitis, with respect to the gut-liver axis, using a rat model.

METHODS

Nonalcoholic steatohepatitis model rats were randomly assigned into 3 groups as follows: 1 sham group and 2 duodenal-jejunal bypass groups. The 2 duodenal-jejunal bypass groups were defined according to the bilio-pancreatic limb length: 30 cm (30-DJB group) and 0 cm (0-DJB group). Pathology findings and blood biochemistry, inflammatory cytokine and lipopolysaccharides receptor mRNA in the liver and common channel, and lipopolysaccharide-binding protein level in the portal vein were assessed.

RESULTS

The reduction in plasma alanine aminotransferase and nonalcoholic fatty liver disease activity score in the 30-DJB group was not observed in the 0-DJB group, similar to the sham group. In the liver tissue, mRNA of inflammatory cytokines and lipopolysaccharide receptors, the area occupied by CD68-positive macrophages, and the number of CD3-positive T-lymphocytes on immunostaining were lower in the 30-DJB group; however, these findings were not observed in the 0-DJB group, and lipopolysaccharide-binding protein levels in the portal vein and mRNA expressions of inflammation-related genes in the common channel showed similar tendencies.

CONCLUSION

The bilio-pancreatic limb plays an important role in the beneficial effect of duodenal-jejunal bypass for nonalcoholic steatohepatitis. The bilio-pancreatic limb may suppress lipopolysaccharides-related cascades in the liver by reducing intestinal inflammation.

Mechanism of Bile Acid Reabsorption in the Biliopancreatic Limb After Duodenal-Jejunal Bypass in Rats

BACKGROUND

Bile acids (BAs) are important in the metabolic effects of bariatric surgery. Most BAs are reabsorbed in the ileum and recycled back to the liver. We have reported that this enterohepatic circulation was shortened by duodenal-jejunal bypass (DJB), and the biliopancreatic (BP)-limb plays an important role in reabsorption of BAs. However, the mechanism of BA reabsorption in BP-limb remains uncertain. We aimed to investigate the mechanisms of BA reabsorption after DJB, especially focusing on carrier-mediated transport of BAs and the impact of the presence or absence of lipids on BA reabsorption.

METHODS

Otsuka-Long-Evans-Tokushima fatty rats or Sprague-Dawley rats were assigned to a control group and DJB group. BA levels in the divided small intestine were quantified with liquid chromatography-mass spectrometry. Labeled BA was injected and perfused with BA transporter inhibitors or mixture of lipids in the isolated BP-limb, and bile was sampled and analyzed.

RESULTS

Conjugated BA levels in the BP-limb were significantly higher than that of the control group. BA absorption tended to decrease by the apical sodium-dependent BA transporter inhibitor and was significantly decreased by the organic anion-transporting peptide (OATP) inhibitor. BA absorption tended to increase in the absence of lipid solutions compared with that in the presence of lipid solutions.

CONCLUSION

We attributed the increased BA reabsorption in the BP-limb to lack of food in the BP-limb, which contains concentrated BAs and no lipids. OATP played an important role in BA reabsorption in the BP-limb. Therefore, BAs would be reabsorbed in different manners after DJB.

Putting the Hindgut Hypothesis to the Test in a Diabetic Zucker Rat Model

BACKGROUND

The hindgut theory hypothesizes a key role of differential hindgut stimulation following metabolic procedures in ameliorating diabetes mellitus. We used two strategies to remove the hindgut from intestinal continuity in order to analyze its impact on diabetes mellitus.

METHODS

Loop duodeno-jejunostomy (DJOS) with exclusion of one-third of total intestinal length was performed in 3 groups of 9-week-old Zucker diabetic fatty rats. In group 1, no further alteration of the intestinal tract was made. Group 2 received additional ileal exclusion (IE). Group 3 underwent additional resection of 50% of the ileum with side-to-side ileocecal anastomosis (IR). One, 2, and 4 months after surgery, fasting blood glucose levels, oral glucose tolerance tests (OGTT), and glucose-stimulated hormone analyses were conducted, and bile acid blood levels were compared. Body weight was documented weekly.

RESULTS

In relation to DJOS, glucose control was not impaired in IR or IE. On the contrary, only IR could maintain preOP glucose values until 4 months. There were no significant weight differences between the groups. Confirming effective ileal diversion, bile acid blood levels were significantly higher in the DJOS group compared with both IR and IE (p = 0.0025 and p = 0.0047). Operative interventions had no impact on GLP-1 levels at any time point (ANOVA p > 0.05 for all). Insulin secretion was preserved in all groups.

CONCLUSION

This data supports the hypothesis that the mechanisms driving amelioration of diabetes mellitus are complex and cannot be reduced to the ileum.

Increased Bile Acid Signals After Duodenal-Jejunal Bypass Improve Non-alcoholic Steatohepatitis (NASH) in a Rodent Model of Diet-Induced NASH

BACKGROUND

The increasing incidence of non-alcoholic steatohepatitis (NASH) has resulted in it becoming a common cause of liver-related mortality; however, no efficient treatment has been established. It has been reported that bariatric surgery improves metabolic comorbidities, such as diabetes mellitus and NASH. Although the mechanism is unclear, it is thought that the changes in bile acid (BA) signaling via its nuclear receptor, farnesoid X receptor (FXR), produce various metabolic effects. We sought to investigate the effects and mechanisms of bariatric surgery on NASH improvement.

METHODS

Male Sprague-Dawley rats were fed by a high-fat and high-fructose diet, which results in obesity, insulin resistance, and NASH. Rats underwent duodenal-jejunal bypass (DJB), which is a main component of bariatric procedures. The liver pathological findings and the expression level of mRNA of FXR were investigated. The plasma BA level was measured in peripheral and portal vein blood.

RESULTS

DJB suppressed weight gain, improved insulin resistance, and ameliorated NASH mainly in a point of inflammation. The plasma BA level along with the expression of FXR and its target transcriptional factor, small heterodimer partner (SHP), in the liver were elevated.

CONCLUSIONS

DJB has a direct effect on NASH improvement, and there is a possibility that an anti-inflammatory effect is functioning as a part of the mechanism. The increase of plasma bile acid level followed by the stimulation of FXR signaling may contribute to this phenomenon.

Meal patterns after bariatric surgery in mice and rats

With behavioral and pharmacological interventions continuously failing to tackle the obesity epidemic, bariatric surgery has been hailed as the most effective treatment strategy. Current literature suggests that bariatric surgery successfully decreases body weight and excess fat mass through targeting both variables of the energy homeostasis - energy intake and energy expenditure. Here we review current knowledge on changes in caloric consumption, an important arm in the energy balance equation, in rodent models of bariatric surgery. In particular, circadian feeding dynamics, post-surgical caloric intake at both "rapid weight loss" phase and "weight maintenance" phase, as well as meal pattern analysis will be the subject of this review. Considering that different types of bariatric surgery may trigger differential energy intake dynamics resulting in variable weight loss outcomes, the effects of most popular surgeries - vertical sleeve gastrectomy (VSG), Roux-en-Y gastric bypass (RYGB), and gastric banding (GB) - are elaborated. Potential candidate mechanisms underlying alterations in food intake and meal patterns following different bariatric procedures are briefly discussed at the end.

Efficacy of Sleeve Gastrectomy with Duodenal-Jejunal Bypass for the Treatment of Obese Severe Diabetes Patients in Japan: a Retrospective Multicenter Study

BACKGROUND

The incidence of obesity with type 2 diabetes (T2DM) is increasing in Japan. The main bariatric surgery procedures in Japan are laparoscopic sleeve gastrectomy (LSG) and LSG with duodenal-jejunal bypass (LSG/DJB) because of the high incidence of gastric cancer and difficulty exploring a remnant stomach after gastric bypass. However, few studies have compared the antidiabetic effect of LSG/DJB with LSG alone.

PURPOSE

The purpose of this study is to compare the antidiabetic effect of LSG/DJB with that of LSG alone in Japanese obese diabetic patients.

METHODS

This was a retrospective multicenter study including 298 cases: 177 and 121 LSG and LSG/DJB cases, respectively. We investigated the antidiabetic effect of these two procedures at 12 months after surgery. Univariate and multivariate analyses were done to evaluate the predictive factors of T2DM remission.

RESULTS

The diabetes remission rate at 12 months after surgery was 80.8% for LSG and 86.0% for LSG/DJB. Insulin use and HbA1c ≤ 6.7% were significant predictive factors in multivariate analysis for all patients. In patients with ABCD score ≥ 6, the diabetes remission rate was 94.8% and there was no difference between procedures. Only duration of diabetes and insulin use were significant predictive factors both in univariate and multivariate analyses. However, in cases with ABCD score ≤ 5, the remission rate was 70.3% and procedure type was the most significant predictive factor for diabetes remission (odds ratio [OR] 5.140).

CONCLUSIONS

Although both LSG and LSG/DJB have good antidiabetic effects in Japanese obese patients, LSG/DJB is more effective for patients with lower ABCD scores.

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.

Biliopancreatic limb plays an important role in metabolic improvement after duodenal-jejunal bypass in a rat model of diabetes

BACKGROUND AND AIMS

Roux-en-Y gastric bypass improves glucose metabolism in clinical practice, and duodenal-jejunal bypass (DJB), an experimental bypass procedure, also improves metabolism in animals. However, the mechanism remains controversial; especially, the role of the biliopancreatic limb (BP-limb) remains unclear. Our aim was to examine the importance of the function of the BP-limb after DJB using a novel operative model.

METHODS

Otsuka Long-Evans Tokushima Fatty rats with diabetes were divided into the following groups: DJB with a short alimentary limb (A-limb) and long BP-limb (B-DJB group), DJB with jejunectomy (J-DJB group) in which the entire length of the jejunum used for the BP-limb of the B-DJB group was excised; and a sham operation group. Glucose tolerance, plasma bile acid levels, and the gut microbiota were assessed postoperatively.

RESULTS

Glucose tolerance was improved and weight gain was suppressed after surgery in the B-DJB group. In contrast, these effects were cancelled in the J-DJB group. The plasma levels of bile acids in the B-DJB group were greater than those in other groups. The analysis of gut microbiota showed distinct differences between the B-DJB and other groups; especially, the relative abundance of genus Bifidobacterium was much higher in the B-DJB group.

CONCLUSION

The BP-limb played an important role in the control of weight gain, glucose tolerance, and increased plasma bile acid levels after DJB in this rat model of type 2 diabetes mellitus. Plasma bile acids and gut microbiota may be involved in these processes.

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.

Detailed characterization of incretin cell distribution along the human small intestine

BACKGROUND

Incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1), are physiologic stimulants of insulin release that have been implicated in diabetes remission after bariatric surgery. The detailed distribution of incretin cells along the human small gut, so far unknown, is of utmost importance for the understanding of the metabolic changes observed after bariatric surgery because diabetes remission rate varies according to the type of anatomic rearrangement.

OBJECTIVE

To characterize the distribution of incretin producing cells along the human jejunum-ileum.

SETTING

Academic public institution.

METHODS

Small intestines (n = 30) from autopsies were sampled every 20 cm along their entire length and tissue microarrays were constructed. The percentage of immunohistochemistry-stained cell areas for GLP-1, GIP, and chromogranin A at each segment length was quantified using a computer-aided analysis tool.

RESULTS

The percentage of stained area for GLP-1 immunoreactive cells was found to be significantly higher from 200 cm from Treitz ligament onward compared with the first 80 cm of the small intestine, whereas GIP immunoreactive cells were predominant expressed in the first 80 cm. In contrast, chromogranin A expression was constant along the entire jejunum-ileum.

CONCLUSION

The uneven distribution of GLP-1-expressing cells, with a higher density from 200 cm of the jejunum-ileum, could contribute to explain the improvement of glycemic profile of diabetic patients observed after anatomic rearrangement of the intestinal tract, in particular when subjected to gastric bypass with longer biliopancreatic limbs.