Differential effects of gastric bypass and banding on circulating gut hormone and leptin levels

Gut motility and hormone changes after bariatric procedures

PURPOSE OF REVIEW

Metabolic and bariatric surgery (MBS) and endoscopic bariatric therapies (EBT) are being increasingly utilized for the management of obesity. They work through multiple mechanisms, including restriction, malabsorption, and changes in the gastrointestinal hormonal and motility.

RECENT FINDINGS

Roux-en-Y gastric bypass (RYGB) and laparoscopic sleeve gastrectomy (LSG) cause decrease in leptin, increase in GLP-1 and PYY, and variable changes in ghrelin (generally thought to decrease). RYGB and LSG lead to rapid gastric emptying, increase in small bowel motility, and possible decrease in colonic motility. Endoscopic sleeve gastroplasty (ESG) causes decrease in leptin and increase in GLP-1, ghrelin, and PYY; and delayed gastric motility.

SUMMARY

Understanding mechanisms of action for MBS and EBT is critical for optimal care of patients and will help in further refinement of these interventions.

Glucose metabolism after bariatric surgery: implications for T2DM remission and hypoglycaemia

Although promising therapeutics are in the pipeline, bariatric surgery (also known as metabolic surgery) remains our most effective strategy for the treatment of obesity and type 2 diabetes mellitus (T2DM). Of the many available options, Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) are currently the most widely used procedures. RYGB and VSG have very different anatomical restructuring but both surgeries are effective, to varying degrees, at inducing weight loss and T2DM remission. Both weight loss-dependent and weight loss-independent alterations in multiple tissues (such as the intestine, liver, pancreas, adipose tissue and skeletal muscle) yield net improvements in insulin resistance, insulin secretion and insulin-independent glucose metabolism. In a subset of patients, post-bariatric hypoglycaemia can develop months to years after surgery, potentially reflecting the extreme effects of potent glucose reduction after surgery. This Review addresses the effects of bariatric surgery on glucose regulation and the potential mechanisms responsible for both the resolution of T2DM and the induction of hypoglycaemia.

Effects of Roux-en-Y gastric bypass on the metabolic profile and systemic inflammatory status of women with metabolic syndrome: randomized controlled clinical trial

BACKGROUND

Obesity remains a public health problem worldwide. The high prevalence of this condition in the population raises further concerns, considering that comorbidities are often associated with obesity. Among the comorbidities closely associated with obesity, metabolic syndrome (MS) is particularly important, which potentially increases the risk of manifestation of other disorders, such as the prothrombotic and systemic pro-inflammatory states.

METHODS

A randomized, controlled clinical trial was performed involving female patients (n = 32) aged between 18 and 65 years, with a clinical diagnosis of MS, with severe obesity undergoing Roux-en-Y gastric bypass (RYGB). The study design followed the Consolidated Standards of Reporting Trials statement (CONSORT). Lipid profile, blood glucose and adipokines (adiponectin, leptin, and resistin) and (cytokines IL-1β, IL-6, IL-17, IL-23, and TNF-α) in blood plasma samples were evaluated before and six months after RYGB.

RESULTS

Patients undergoing RYGB (BSG) showed a significant improvement from preoperative grade III obesity to postoperative grade I obesity. The results showed that while HDL levels increased, the other parameters showed a significant reduction in their postoperative values when compared not only to the values observed before surgery in the BSG group, but also to the values obtained in the control group (CG). As for systemic inflammatory markers adiponectin, leptin, resistin, IL-1β, IL-6, IL-17, IL-23 and TNF- α it was observed that the levels of resistin and IL-17 in the second evaluation increased significantly when compared to the levels observed in the first evaluation in the CG. In the BSG group, while the levels of adiponectin increased, the levels of the other markers showed significant reductions in the postoperative period, in relation to the respective preoperative levels. The analysis of Spearman's correlation coefficient showed a significant positive correlation between IL-17 and IL-23 in the preoperative period, significant positive correlations between TNF-α and IL-6, TNF-α and IL-17, IL-6 and IL-17, and IL-17 and IL-23 were observed postoperatively.

CONCLUSIONS

According to our results, the reduction of anthropometric measurements induced by RYGB, significantly improves not only the plasma biochemical parameters (lipid profile and glycemia), but also the systemic inflammatory status of severely obese patients with MS. Trials registration NCT02409160.

Gut Factors Mediating the Physiological Impact of Bariatric Surgery

Despite decades of obesity research and various public health initiatives, obesity remains a major public health concern. Our most drastic but most effective treatment of obesity is bariatric surgery with weight loss and improvements in co-morbidities, including resolution of type 2 diabetes (T2D). However, the mechanisms by which surgery elicits metabolic benefits are still not well understood. One proposed mechanism is through signals generated by the intestine (nutrients, neuronal, and/or endocrine) that communicate nutrient status to the brain. In this review, we discuss the contributions of gut-brain communication to the physiological regulation of body weight and its impact on the success of bariatric surgery. Advancing our understanding of the mechanisms that drive bariatric surgery-induced metabolic benefits will ultimately lead to the identification of novel, less invasive strategies to treat obesity.

Roux-en-Y Gastric Bypass and Caloric Restriction but Not Gut Hormone-Based Treatments Profoundly Impact the Hypothalamic Transcriptome in Obese Rats

BACKGROUND

The hypothalamus is an important brain region for the regulation of energy balance. Roux-en-Y gastric bypass (RYGB) surgery and gut hormone-based treatments are known to reduce body weight, but their effects on hypothalamic gene expression and signaling pathways are poorly studied.

METHODS

Diet-induced obese male Wistar rats were randomized into the following groups: RYGB, sham operation, sham + body weight-matched (BWM) to the RYGB group, osmotic minipump delivering PYY3-36 (0.1 mg/kg/day), liraglutide s.c. (0.4 mg/kg/day), PYY3-36 + liraglutide, and saline. All groups (except BWM) were kept on a free choice of high- and low-fat diets. Four weeks after interventions, hypothalami were collected for RNA sequencing.

RESULTS

While rats in the RYGB, BWM, and PYY3-36 + liraglutide groups had comparable reductions in body weight, only RYGB and BWM treatment had a major impact on hypothalamic gene expression. In these groups, hypothalamic leptin receptor expression as well as the JAK-STAT, PI3K-Akt, and AMPK signaling pathways were upregulated. No significant changes could be detected in PYY3-36 + liraglutide-, liraglutide-, and PYY-treated groups.

CONCLUSIONS

Despite causing similar body weight changes compared to RYGB and BWM, PYY3-36 + liraglutide treatment does not impact hypothalamic gene expression. Whether this striking difference is favorable or unfavorable to metabolic health in the long term requires further investigation.

Impact of Gastropexy/Omentopexy on Gastrointestinal Symptoms after Laparoscopic Sleeve Gastrectomy

Background

Laparoscopic sleeve gastrectomy (LSG) has become a single-step operation for the management of severe obesity. A statistically significant number of participants who undergo this procedure experience nausea, vomiting, and reflux symptoms early after the operation. The objectives of this study were to measure the positive or negative effect of gastropexy on reducing distressing postoperative LSG-related gastrointestinal symptoms.

Patients and Methods

This was a comparative randomized study conducted from January 2018 to January 2021. The study was carried out in the general surgery department at Menoufia University Hospital, Menoufia Faculty of Medicine in Egypt. Two hundred participants were included randomly during this trial. The participants were divided into two groups, with 100 patients in each group. Patients in group A underwent gastropexy, and patients in group B underwent LSG without gastropexy.

Results

There was no significant difference between the groups in age or sex (p > 0.05). There was no significant difference in the length of hospital stay (p > 0.05). There was a significant difference between the two groups regarding nausea, vomiting, reflux symptoms, and the amount and frequency of antiemetics used (p < 0.001). There was also a significant difference in hospital readmissions (p < 0.05) and in clinic visits during the postoperative period.

Conclusions

Patients who underwent gastropexy showed a significant reduction in antiemetic consumption and a significantly lower incidence of postoperative nausea, vomiting, gastroesophageal reflux disease symptoms and gastric torsion than those who did not undergo gastropexy.

Graphical abstract

A novel approach to treating opioid use disorders: Dual agonists of glucagon-like peptide-1 receptors and neuropeptide Y2 receptors

The widespread misuse of opioids and opioid use disorder (OUD) together constitute a major public health crisis in the United States. The greatest challenge for successfully treating OUD is preventing relapse. Unfortunately, there are few FDA-approved medications to treat OUD and, while effective, these pharmacotherapies are limited by high relapse rates. Thus, there is a critical need for conceptually new approaches to developing novel medications to treat OUD. Here, we review an emerging preclinical literature that suggests that glucagon-like peptide-1 receptor (GLP-1R) agonists could be re-purposed for treating OUD. Potential limitations of this approach are also discussed along with an alternative strategy that involves simultaneously targeting and activating GLP-1Rs and neuropeptide Y2 receptors (Y2Rs) in the brain using a novel monomeric dual agonist peptide. Recent studies indicate that this combinatorial pharmacotherapy approach attenuates voluntary fentanyl taking and seeking in rats without producing adverse effects associated with GLP-1R agonist monotherapy alone. While future studies are required to comprehensively determine the behavioral effects of GLP-1R agonists and dual agonists of GLP-1Rs and Y2Rs in rodent models of OUD, these provocative preclinical findings highlight a potential new GLP-1R-based approach to preventing relapse in humans with OUD.

Gastrointestinal peptides in eating-related disorders

Food intake is tightly controlled by homeostatic signals sensitive to metabolic need for the regulation of body weight. This review focuses on the peripherally-secreted gastrointestinal peptides (i.e., ghrelin, cholecystokinin, glucagon-like peptide 1, and peptide tyrosine tyrosine) that contribute to the control of appetite and discusses how these peptides or the signals arising from their release are disrupted in eating-related disorders across the weight spectrum, namely anorexia nervosa, bulimia nervosa, and obesity, and whether they are normalized following weight restoration or weight loss treatment. Further, the role of gut peptides in the pathogenesis and treatment response in human weight conditions as identified by rodent models are discussed. Lastly, we review the incretin- and hormone-based pharmacotherapies available for the treatment of obesity and eating-related disorders.

Neuropeptide Y and Peptide YY in Association with Depressive Symptoms and Eating Behaviours in Adolescents across the Weight Spectrum: From Anorexia Nervosa to Obesity

Neuropeptide Y (NPY) and peptide YY (PYY) are involved in metabolic regulation. The purpose of the study was to assess the serum levels of NPY and PYY in adolescents with anorexia nervosa (AN) or obesity (OB), as well as in a healthy control group (CG). The effects of potential confounders on their concentrations were also analysed. Eighty-nine adolescents were included in this study (AN = 30, OB = 30, and CG = 29). Anthropometric measurements and psychometric assessment of depressive symptoms, eating behaviours, body attitudes, and fasting serum levels of NPY and PYY were analysed. The AN group presented severe depressive symptoms, while the OB group held different attitudes towards the body. The levels of NPY were lower in the AN and OB groups as compared with the CG. The PYY levels were higher in the OB group than in the AN group and the CG. The severity of eating disorder symptoms predicted fasting serum concentrations of NPY. Lower levels of NPY in AN, as well as in OB suggests the need to look for a common link in the mechanism of this effect. Higher level of PYY in OB may be important in explaining complex etiopathogenesis of the disease. The psychopathological symptoms may have an influence on the neurohormones regulating metabolism.

Electronic Bypass for Diabetes: Optimization of Stimulation Parameters and Mechanisms of Glucagon-Like Peptide-1

OBJECTIVES

Intestinal electrical stimulation (IES) has been proposed for treating diabetes; however, its parameters need to be further systematically optimized. This study aimed to optimize the parameters of IES and investigate its possible mechanisms involving glucagon-like peptide-1 (GLP-1) in diabetic rats.

MATERIALS AND METHODS

Thirty-six high-fat diet-induced diabetic rats were chronically implanted with a pair of bipolar electrodes at the duodenum for IES. The oral glucose tolerance test (OGTT) was performed in a number of sessions with IES using different parameters and biphasic charge-balanced waveforms to derive the best values for train on-time, pulse frequency, and pulse width. Incretin hormones such as GLP-1 were assessed and the GLP-1 antagonist Exendin 9-39 was used to assess the role of GLP-1 in the ameliorating effect of IES on hyperglycemia.

RESULTS

The most effective IES parameters in reducing blood glucose (BG) during the OGTT were derived: 1.2 sec on, 0.3 sec off, 80 Hz, 3 msec. IES with these parameters reduced BG level by at least 29% from 15 min to 180 min (p < 0.05 for all points, N = 10). IES with these stimulation parameters increased plasma GLP-1 level at 30 min, 60 min, 90 min and gastric inhibitory peptide (GIP) level at 30 min (N = 8). Exendin 9-39 blocked the inhibitory effect of IES on BG (p > 0.05, IES + Exendin 9-39 vs. sham-IES, N = 8).

CONCLUSION

IES with the most effective parameters derived in this study improves hyperglycemia in diabetic rats. The ameliorating effect of IES on hyperglycemia is attributed to the enhanced release of GLP-1. IES has great potential for treating diabetes.

The Phantom Satiation Hypothesis of Bariatric Surgery

The excitation of vagal mechanoreceptors located in the stomach wall directly contributes to satiation. Thus, a loss of gastric innervation would normally be expected to result in abrogated satiation, hyperphagia, and unwanted weight gain. While Roux-en-Y-gastric bypass (RYGB) inevitably results in gastric denervation, paradoxically, bypassed subjects continue to experience satiation. Inspired by the literature in neurology on phantom limbs, I propose a new hypothesis in which damage to the stomach innervation during RYGB, including its vagal supply, leads to large-scale maladaptive changes in viscerosensory nerves and connected brain circuits. As a result, satiation may continue to arise, sometimes at exaggerated levels, even in subjects with a denervated or truncated stomach. The same maladaptive changes may also contribute to dysautonomia, unexplained pain, and new emotional responses to eating. I further revisit the metabolic benefits of bariatric surgery, with an emphasis on RYGB, in the light of this phantom satiation hypothesis.

What Is an L-Cell and How Do We Study the Secretory Mechanisms of the L-Cell?

Synthetic glucagon-like peptide-1 (GLP-1) analogues are effective anti-obesity and anti-diabetes drugs. The beneficial actions of GLP-1 go far beyond insulin secretion and appetite, and include cardiovascular benefits and possibly also beneficial effects in neurodegenerative diseases. Considerable reserves of GLP-1 are stored in intestinal endocrine cells that potentially might be mobilized by pharmacological means to improve the body's metabolic state. In recognition of this, the interest in understanding basic L-cell physiology and the mechanisms controlling GLP-1 secretion, has increased considerably. With a view to home in on what an L-cell is, we here present an overview of available data on L-cell development, L-cell peptide expression profiles, peptide production and secretory patterns of L-cells from different parts of the gut. We conclude that L-cells differ markedly depending on their anatomical location, and that the traditional definition of L-cells as a homogeneous population of cells that only produce GLP-1, GLP-2, glicentin and oxyntomodulin is no longer tenable. We suggest to sub-classify L-cells based on their differential peptide contents as well as their differential expression of nutrient sensors, which ultimately determine the secretory responses to different stimuli. A second purpose of this review is to describe and discuss the most frequently used experimental models for functional L-cell studies, highlighting their benefits and limitations. We conclude that no experimental model is perfect and that a comprehensive understanding must be built on results from a combination of models.

Guidelines for gastrostomy tube placement and enteral nutrition in patients with severe, refractory hypoglycemia after gastric bypass

BACKGROUND

Postbariatric hypoglycemia (PBH) affects up to 38% of Roux-en-Y gastric bypass (RYGB) patients. Severe cases are refractory to diet and medications. Surgical treatments including bypass reversal and pancreatectomy are highly morbid and hypoglycemia often recurs. We have developed a highly effective method of treatment by which enteral nutrition administered through a gastrostomy (G) tube placed in the remnant stomach replaces oral diet: if done correctly this reverses hyperinsulinemia and hypoglycemia, yielding substantial health and quality of life benefits for severely affected patients.

OBJECTIVES

To provide clinical guidelines for placement of a G-tube to treat postRYGB hypoglycemia, including candidate selection, preoperative evaluation, surgical considerations, and post-RYGB management.

SETTING

Stanford University Hospital and Clinics.

METHODS

Based on our relatively large experience with placing and managing G-tubes for PBH treatment, an interdisciplinary task force developed guidelines for practitioners.

RESULTS

A team approach (endocrinologist, dietitian, surgeon, psychologist) is recommended. Appropriate candidates have a history of RYGB, severe hypoglycemia refractory to medical-nutrition therapy, and significantly affected quality of life. Preoperative requirements include education and expectation setting, determination of initial enteral feeding program, and establishing service with a home enteral provider. Close postoperative follow-up is needed to ensure success and may require adjustments in formula and mode/rate of delivery to optimize tolerance and meet nutritional goals. G-tube nutrition must fully replace oral nutrition to prevent hypoglycemia.

CONCLUSIONS

G-tube placement in the remnant stomach represents a relatively well-tolerated and effective treatment for severe, refractory hypoglycemia after RYGB.

Dipeptidyl peptidase-4 activity, lipopolysaccharide, C-reactive protein, glucose metabolism, and gut peptides 3 months after bariatric surgery

BACKGROUND

Bariatric surgery induces weight loss, but changes in glucose metabolism, gut peptides, and inflammatory biomarkers still have conflicting results.

SETTINGS

University hospital.

OBJECTIVES

We investigated glucose metabolism, gut hormones, and inflammatory profile after bariatric surgery and medical treatment.

METHODS

Forty patients with obesity were recruited and were subjected to Roux-en-Y gastric bypass (n = 15; Bariatric Surgery Group - BSG) or received medical care (n = 20; MG). Sleeve gastrectomy was performed in five patients who were excluded from analysis. Glucose, insulin, homeostatic model for the assessment of insulin resistance (HOMA-IR), glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), glucagon, ghrelin, dipeptidyl peptidase-4 (DPP-4) activity, circulating lipopolysaccharide (LPS), LPS-binding protein (LPB) and high-sensitivity C-reactive protein (hs-CRP) were evaluated before and three months after each treatment. Except for HOMA-IR, hs-CRP, and LBP, all variables were assessed at fasting and 30- and 60-minutes after a standard meal.

RESULTS

After 3 months, both groups lost weight. However, BSG had a more extensive reduction than MG (respectively, 17.6% vs. 4.25%; P < 0.01). Except for LPS levels, higher on BSG than MG (1.38 ± 0.96 vs. 0.83 ± 0.60 EU/ml, P < 0.01), groups were similar before treatment. In respect to metabolic/hormonal changes, the BSG showed higher glucose, insulin, GLP-1, and GIP levels at 30-min and also GLP-1 at 30- and 60-minutes. DPP-4 activity, HOMA-IR, and fasting LBP did not change. LPS levels at 60-minutes decreased after surgery in the BSG. hs-CRP decreased on BSG compared to MG.

CONCLUSIONS

Bariatric surgery resulted in more extensive effects on glucose metabolism, gut hormones, and inflammation.

Prospective study of gut hormone and metabolic changes after laparoscopic sleeve gastrectomy and Roux-en-Y gastric bypass

Background

Laparoscopic sleeve gastrectomy (SG) has surpassed Roux-en-Y gastric bypass (RYGB) as the most prevalent bariatric procedure worldwide. While RYGB and SG demonstrate equivalent short-term weight loss, long-term weight loss tends to be greater after RYGB. Differences in the effect of these procedures on gastrointestinal hormones that regulate energy homeostasis are felt to partially underlie differences in outcomes. The objective of this study was to prospectively quantify blood levels of gut hormones of energy and glucose homeostasis at one year follow up to delineate possible reasons for greater efficacy of RYGB over SG in achieving weight loss.

Methods

Patients undergoing SG (n = 19) and RYGB (n = 40) were studied before surgery and at 2,12, 26, and 52 weeks postoperatively. Blood samples drawn in the fasted state and after a liquid mixed meal were assayed at baseline, 26, and 52 weeks for peptide YY (PYY), glucagon-like peptide-1 (GLP-1), ghrelin, insulin, glucose, and leptin. Fasting and postprandial appetitive sensations were assessed by visual analog scale.

Results

At 1 year there was greater weight loss in RYGB compared with SG patients (30% vs 27%; P = 0.03). Area under the curve (AUC) after the mixed meal for PYY was greater in RYGB patients (P<0.001). RYGB patients had significant increases in GLP-1 AUC compared to baseline (P = 0.002). Ghrelin levels decreased only after SG compared to baseline (P<0.001) but were not significantly different from RYGB. There was a trend toward decreased sweet cravings in RYGB patients (P = 0.056).

Conclusions

Differences in gastrointestinal hormones that regulate energy and glucose homeostasis are a possible mechanism for greater efficacy of RYGB compared to SG.

Integrated Analysis of Key Genes and Pathways Involved in Nonalcoholic Steatohepatitis Improvement After Roux-en-Y Gastric Bypass Surgery

BACKGROUND

As the incidence of nonalcoholic fatty liver disease (NAFLD) increases globally, nonalcoholic steatohepatitis (NASH) has become the second common cause of liver transplantation for liver diseases. Recent evidence shows that Roux-en-Y gastric bypass (RYGB) surgery obviously alleviates NASH. However, the mechanism underlying RYGB induced NASH improvement is still elusive.

METHODS

We obtained datasets, including hepatic gene expression data and histologic NASH status, at baseline and 1 year after RYGB surgery. Differentially expressed genes (DEGs) were identified comparing gene expression before and after RYGB surgery in each dataset. Common DEGs were obtained between both datasets and further subjected to functional and pathway enrichment analysis. Protein-protein interaction (PPI) network was constructed, and key modules and hub genes were also identified.

RESULTS

In the present study, GSE106737 and GSE83452 datasets were included. One hundred thirty common DEGs (29 up-regulated and 101 down-regulated) were identified between GSE106737 and GSE83452 datasets. KEGG analysis showed that mineral absorption, IL-17 signaling pathway, osteoclast differentiation, and TNF signaling pathway were significantly enriched. Based on the PPI network, IGF1, JUN, FOS, LDLR, TYROBP, DUSP1, CXCR4, ATF3, CXCL2, EGR1, SAA1, CTSS, and PPARA were identified as hub genes, and three functional modules were also extracted.

CONCLUSION

This study identifies the global gene expression change in the liver of NASH patients before and after RYGB surgery in a bioinformatic method. Our findings will contribute to the understanding of molecular biological changes underlying NASH improvement after RYGB surgery.

Toward a Medical Gastric Bypass: Chronic Feeding Studies With Liraglutide + PYY3-36 Combination Therapy in Diet-Induced Obese Rats

BACKGROUND

Combination therapies of anorectic gut hormones partially mimic the beneficial effects of bariatric surgery. Thus far, the effects of a combined chronic systemic administration of Glucagon-like peptide-1 (GLP-1) and peptide tyrosine tyrosine 3-36 (PYY_3-36) have not been directly compared to Roux-en-Y gastric bypass (RYGB) in a standardized experimental setting.

METHODS

High-fat diet (HFD)-induced obese male Wistar rats were randomized into six treatment groups: (1) RYGB, (2) sham-operation (shams), (3) liraglutide, (4) PYY_3-36, (5) PYY_3-36+liraglutide (6), saline. Animals were kept on a free choice high- and low-fat diet. Food intake, preference, and body weight were measured daily for 4 weeks. Open field (OP) and elevated plus maze (EPM) tests were performed.

RESULTS

RYGB reduced food intake and achieved sustained weight loss. Combined PYY_3-36+liraglutide treatment led to similar and plateaued weight loss compared to RYGB. Combined PYY_3-36+liraglutide treatment was superior to PYY_3-36 (p ≤ 0.0001) and liraglutide (p ≤ 0.05 or p ≤ 0.01) mono-therapy. PYY_3-36+liraglutide treatment and RYGB also reduced overall food intake and (less pronounced) high-fat preference compared to controls. The animals showed no signs of abnormal behavior in OF or EPM.

CONCLUSIONS

Liraglutide and PYY_3-36 combination therapy vastly mimics reduced food intake, food choice and weight reducing benefits of RYGB.

Proceedings of the 2017 ASPEN Research Workshop-Gastric Bypass: Role of the Gut

The goal of the National Institutes of Health-funded American Society for Parenteral and Enteral Nutrition 2017 research workshop (RW) "Gastric Bypass: Role of the Gut" was to focus on the exciting research evaluating gut-derived signals in modulating outcomes after bariatric surgery. Although gastric bypass surgery has undoubted positive effects, the mechanistic basis of improved outcomes cannot be solely explained by caloric restriction. Emerging data suggest that bile acid metabolic pathways, luminal contents, energy balance, gut mucosal integrity, as well as the gut microbiota are significantly modulated after bariatric surgery and may be responsible for the variable outcomes, each of which was rigorously evaluated. The RW served as a timely and novel academic meeting that brought together clinicians and researchers across the scientific spectrum, fostering a unique venue for interdisciplinary collaboration among investigators. It promoted engaging discussion and evolution of new research hypotheses and ideas, driving the development of novel ameliorative, therapeutic, and nonsurgical interventions targeting obesity and its comorbidities. Importantly, a critical evaluation of the current knowledge regarding gut-modulated signaling after bariatric surgery, potential pitfalls, and lacunae were thoroughly addressed.

Cardiac remodeling in obesity and after bariatric and metabolic surgery; is there a role for gastro-intestinal hormones?

Introduction: Obesity is associated with various diseases such as type 2 diabetes, hypertension, obstructive sleep apnea syndrome (OSAS), metabolic syndrome, and cardiovascular diseases. It affects several organ systems, including the pulmonary and cardiac systems. Furthermore, it induces pulmonary and cardiac changes that can result in right and/or left heart failure.Areas covered: In this review, authors provide an overview of obesity and cardiovascular remodeling, the individual actions of the gut hormones (like GLP-1 and PYY), the effects after bariatric/metabolic surgery and its influence on cardiac remodeling. In this review, we focussed and searched for literature in Pubmed and The Cochrane library (from the earliest date until April 2019), regarding cardiac function changes before and after bariatric surgery and literature regarding changes in gastrointestinal hormones.Expert opinion: Regarding the surgical treatment of obesity and metabolic diseases there is recognition of the importance of both weight loss (bariatric surgery) and improvement in metabolic milieu (metabolic surgery). A growing body of evidence further suggests that bariatric surgical procedures [like the Sleeve Gastrectomy (SG), Roux-en Y Gastric Bypass (RYGB), or One Anastomosis Gastric Bypass (OAGB)] have can improve outcomes of patients suffering from a number of cardiovascular diseases, including heart failure.

The Role of Bariatric Surgery on Diabetes and Diabetic Care Compliance

PURPOSE OF REVIEW

Bariatric surgery is a durable and long-term solution to treat both obesity and its associated comorbidities, specifically type 2 diabetes mellitus (T2DM). Many studies have demonstrated the benefits of bariatric surgery on T2DM, but weight recidivism along with recurrence of comorbidities can be seen following these procedures. Patient compliance post-bariatric surgery is linked to weight loss outcomes and comorbidity improvement/resolution. The role of compliance with respect to T2DM medication in bariatric patients specifically has not recently been examined. This article seeks to review the role of bariatric surgery on short- and long-term resolution of T2DM, recurrence, and compliance with T2DM medication following bariatric surgery.

RECENT FINDINGS

Seven randomized control trials have examined metabolic surgery versus medical therapy in glycemic control in patients meeting criteria for severe obesity. Six out of seven studies demonstrate a significant advantage in the surgical arms with regards to glycemic control, as well as secondary endpoints such as weight loss, serum lipid levels, blood pressure, renal function, and other parameters. While patient compliance with lifestyle modifications post-bariatric surgery is linked to weight loss outcomes, there are no studies to date that directly evaluate the role of lifestyle modifications and T2DM medication adherence in the management of T2DM post-bariatric surgery. Bariatric surgery is an effective treatment option to achieve long-term weight loss and resolution of obesity-related medical comorbidities, specifically T2DM. Patient compliance to lifestyle modifications post-bariatric surgery is linked to weight loss outcomes and comorbidity resolution. The role of diabetic care compliance in bariatric patient outcomes, however, is poorly understood. Further studies are needed to elucidate the predictors and associated risk factors for non-compliance in this patient population.

Mechanisms of Weight Loss After Sleeve Gastrectomy and Adjustable Gastric Banding: Far More Than Just Restriction

Obesity has reached global epidemic proportions in recent decades. Bariatric surgery is currently accepted as most effective in alleviating morbid obesity and related disorders. Sleeve gastrectomy (SG) and adjustable gastric banding (AGB) have gained popularity since the beginning of this century because of their efficacy, safety, and simplicity. SG, in particular, has emerged as the most popular bariatric procedure because of its simpler concept and shorter operative time compared with gastric bypass. Caloric restriction, however, cannot account for the sustained weight loss and improved glucose metabolism seen following SG and AGB. Other mechanisms, including changes in gastrointestinal hormone secretion, rearrangement of hypothalamic and vagal control, alteration in energy expenditure, and re-regulation of bile acid metabolism and the intestinal flora environment, are thought to contribute to the postoperative benefits. This review focuses on clinical and experimental literature addressing the potential mechanisms for SG and AGB procedures in human and animal models. Understanding such mechanisms can provide important insight into how current gastric restrictive procedures work and how future treatments of obesity, both surgical and nonsurgical, can be developed.

Banded versus nonbanded Roux-en-Y gastric bypass: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Bariatric surgery is remarkably effective in achieving weight loss and improving obesity-related co-morbidities; however, efforts still continue to improve its long-term outcomes. Particularly, banded Roux-en-Y gastric bypass (RYGB) has been scrutinized in comparison to standard (nonbanded) RYGB in terms of benefits and postoperative complications.

OBJECTIVES

This study aims to compare the safety and efficacy of banded versus nonbanded RYGB.

SETTING

Meta-analysis of randomized controlled trials (RCTs).

METHODS

A meta-analysis of high-quality studies that compared banded and nonbanded RYGB was conducted through February 2019 by systematically searching multiple electronic databases. Published RCTs comparing these 2 procedures were included to pool the data on excess weight loss, food tolerability, and postoperative complications.

RESULTS

Three RCTs were eligible to be included in this meta-analysis, comprising a total of 494 patients (247 in each group). Two of the RCTs provided 2-year postoperative data, and 1 study reported 5-year outcome. Age ranged from 21 to 50 years, and body mass index ranged from 42 to 65 kg/m². Percentage of excess weight loss was significantly greater with banded RYGB than with nonbanded RYGB (mean difference 5.63%; 95% CI 3.26-8.00; P < .05). Postoperative food intolerance, emesis, and dysphagia were more common after banded RYGB (odds ratio 3.76; 95% CI 2.27-6.24; P < .001). Nevertheless, major postoperative complications did not significantly differ between the 2 groups.

CONCLUSION

Findings of this meta-analysis of RCTs indicate that in a medium-term follow-up, excess weight loss with banded RYGB would be 5% greater than that with the nonbanded RYGB (about 1 point difference in body mass index) at the expense of more food intolerance and postoperative vomiting; however, the frequency of postoperative complications would not be significantly different.

Metabolic surgery for the treatment of type 2 diabetes in patients with BMI lower than 35 kg/m2 : Why caution is still needed

Bariatric surgery has shifted from being a risky procedure to an evidence-based one, with proven benefits on all-cause mortality, cardiovascular disease, cancer, and diabetes control. The procedure has an overall positive result on type 2 diabetes mellitus (T2DM), with a substantial number of patients achieving disease remission. This has resulted in several studies assessing possible weight-independent effects of bariatric surgery on glycemic improvement, in addition to recommendation of the procedure to patients with class 1 obesity and T2DM, for whom the procedure was classically not indicated, and adoption of a new term, "metabolic surgery," to highlight the overall metabolic benefit of the procedure beyond weight loss. Recently, the Diabetes Surgery Summit (DSS) has included metabolic surgery in its T2DM treatment algorithm. Although the discussion brought by this consensus is highly relevant, the recommendation of metabolic surgery for patients with uncontrolled T2DM and a body mass index of 30 to 35 kg/m² still lacks enough evidence. This article provides an overall view of the metabolic benefits of bariatric/metabolic surgery in patients with class 1 obesity, compares the procedure against clinical treatment, and presents our rationale for defending caution on recommending the procedure to less obese individuals.

Mechanisms for the metabolic success of bariatric surgery

To date, bariatric surgery remains the most effective strategy for the treatment of obesity and its comorbidities. However, given the enormity of the obesity epidemic, and sometimes variable results, it is not a feasible strategy for the treatment of all obese patients. A simple PubMed search for 'bariatric surgery' reveals over 28 000 papers that have been published since the 1940s when the first bariatric surgeries were performed. However, there is still an incomplete understanding of the mechanisms for the weight loss and metabolic success of surgery. An understanding of the mechanisms is important because it may lead to greater understanding of the pathophysiology of obesity and thus surgery-alternative strategies for the treatment of all obese patients. In this review, the potential mechanisms that underlie the success of surgery are discussed, with a focus on the potential endocrine, neural and other circulatory factors (eg, bile acids) that have been proposed to play a role.

Intestinal electrical stimulation attenuates hyperglycemia and prevents loss of pancreatic β cells in type 2 diabetic Goto-Kakizaki rats

BACKGROUND/OBJECTIVE

Recently, intestinal electrical stimulation (IES) has been reported to result in weight loss; however, it is unclear whether it has a therapeutic potential for diabetes. The aim of the present study was to explore the potential hypoglycemic effects of IES and its possible mechanisms involving β cells in diabetic rats.

SUBJECTS/METHODS

Diabetic Goto-Kakizaki (GK) rats were chronically implanted with one pair of electrodes in the duodenum. The oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were performed with or without IES, and plasma glucagon-like peptide-1 (GLP-1) and insulin level were measured. In the other two OGTT sessions, rats were treated with either Exendin (9-39) (GLP-1 antagonist) or Exendin (9-39) plus IES to investigate the underlying mechanism involving GLP-1. Gastric emptying and small intestinal transit were also measured with or without IES. In a chronic study, GK rats were treated with IES or Sham-IES for 8 weeks. Blood glucose, plasma GLP-1 and insulin level, body weight, and food intake were measured. Pancreas weight, islet β-cell apoptosis, and proliferation were also analyzed.

RESULTS

Acute IES reduced blood glucose level from 60 to 120 min during OGTT by 16-20% (all p < 0.05, vs. Sham-IES). GLP-1 antagonist significantly blocked the inhibitory effect of IES on hyperglycemia from 15 to 120 min (all p < 0.05). IES accelerated the small intestinal transit by 15% (p = 0.004). After 8 weeks of chronic stimulation, IES significantly reduced blood glucose (p < 0.05) and body weight (p = 0.02) and increased the plasma GLP-1 concentration (p < 0.05). Furthermore, we observed that chronic IES reduced pancreatic β-cell apoptosis (p = 0.045), but showed no effects on β-cell proliferation.

CONCLUSIONS

Our study firstly proved the hypoglycemic effect of IES in a rodent model of type 2 diabetes, possibly attributed to the increasing GLP-1 secretion and improvement in β-cell functions.

Metabolic and Endocrine Consequences of Bariatric Surgery

Obesity is one of the most serious worldwide epidemics of the twenty-first century according to the World Health Organization. Frequently associated with a number of comorbidities, obesity threatens and compromises individual health and quality of life. Bariatric surgery (BS) has been demonstrated to be an effective treatment to achieve not only sustained weight loss but also significant metabolic improvement that goes beyond mere weight loss. The beneficial effects of BS on metabolic traits are so widely recognized that some authors have proposed BS as metabolic surgery that could be prescribed even for moderate obesity. However, most of the BS procedures imply malabsorption and/or gastric acid reduction which lead to nutrient deficiency and, consequently, further complications could be developed in the long term. In fact, BS not only affects metabolic homeostasis but also has pronounced effects on endocrine systems other than those exclusively involved in metabolic function. The somatotropic, corticotropic, and gonadal axes as well as bone health have also been shown to be affected by the various BS procedures. Accordingly, further consequences and complications of BS in the long term in systems other than metabolic system need to be addressed in large cohorts, taking into account each bariatric procedure before making generalized recommendations for BS. In this review, current data regarding these issues are summarized, paying special attention to the somatotropic, corticotropic, gonadal axes, and bone post-operative health.

Food Intake and Eating Behavior After Bariatric Surgery

Obesity is an escalating global chronic disease. Bariatric surgery is a very efficacious treatment for obesity and its comorbidities. Alterations to gastrointestinal anatomy during bariatric surgery result in neurological and physiological changes affecting hypothalamic signaling, gut hormones, bile acids, and gut microbiota, which coalesce to exert a profound influence on eating behavior. A thorough understanding of the mechanisms underlying eating behavior is essential in the management of patients after bariatric surgery. Studies investigating candidate mechanisms have expanded dramatically in the last decade. Herein we review the proposed mechanisms governing changes in eating behavior, food intake, and body weight after bariatric surgery. Additive or synergistic effects of both conditioned and unconditioned factors likely account for the complete picture of changes in eating behavior. Considered application of strategies designed to support the underlying principles governing changes in eating behavior holds promise as a means of optimizing responses to surgery and long-term outcomes.

Central Modulation of Energy Homeostasis and Cognitive Performance After Bariatric Surgery

In moderately or morbidly obese patients, bariatric surgery has been proven to be an effective therapeutic approach to control body weight and comorbidities. Surgery-mediated modulation of brain function via modified postoperative secretion of gut peptides and vagal nerve stimulation was identified as an underlying mechanism in weight loss and improvement of weight-related diseases. Increased basal and postprandial plasma levels of gastrointestinal hormones like glucagon-like peptide 1 and peptide YY that act on specific areas of the hypothalamus to reduce food intake, either directly or mediated by the vagus nerve, are observed after surgery while suppression of meal-induced ghrelin release is increased. Hormones released from the adipose tissue like leptin and adiponectin are also affected and leptin plasma levels are reduced in treated patients. Besides homeostatic control of body weight, surgery also changes hedonistic behavior in regard to food intake and cognitive performance involving the limbic system and prefrontal areas.

Ghrelin, a gastrointestinal hormone, regulates energy balance and lipid metabolism

Ghrelin, an acylated peptide hormone of 28 amino acids, is an endogenous ligand of the released growth hormone secretagogue receptor (GHSR). Ghrelin has been isolated from human and rat stomach and is also detected in the hypothalamic arcuate nucleus. Ghrelin receptor is primarily located in the neuropeptide Y and agouti-related protein neurons. Many previous studies have shown that ghrelin and GHSR are involved in the regulation of energy homeostasis, and its administration can increase food intake and body weight gain. AMP-activated protein kinase is activated by ghrelin in the hypothalamus, which contributes to lower intracellular long-chain fatty acid level. Ghrelin appears to modulate the response to food cues via a neural network involved in the regulation of feeding and in the appetitive response to food cues. It also increases the response of brain areas involved in visual processing, attention, and memory to food pictures. Ghrelin is also an important factor linking the central nervous system with peripheral tissues that regulate lipid metabolism. It promotes adiposity by the activation of hypothalamic orexigenic neurons and stimulates the expression of fat storage-related proteins in adipocytes. Meanwhile, ghrelin exerts direct peripheral effects on lipid metabolism, including increase in white adipose tissue mass, stimulation of lipogenesis in the liver, and taste sensitivity modulation.

The Gut-Brain Axis, the Human Gut Microbiota and Their Integration in the Development of Obesity

Obesity is a global epidemic, placing socioeconomic strain on public healthcare systems, especially within the so-called Western countries, such as Australia, United States, United Kingdom, and Canada. Obesity results from an imbalance between energy intake and energy expenditure, where energy intake exceeds expenditure. Current non-invasive treatments lack efficacy in combating obesity, suggesting that obesity is a multi-faceted and more complex disease than previously thought. This has led to an increase in research exploring energy homeostasis and the discovery of a complex bidirectional communication axis referred to as the gut-brain axis. The gut-brain axis is comprised of various neurohumoral components that allow the gut and brain to communicate with each other. Communication occurs within the axis via local, paracrine and/or endocrine mechanisms involving a variety of gut-derived peptides produced from enteroendocrine cells (EECs), including glucagon-like peptide 1 (GLP1), cholecystokinin (CCK), peptide YY3-36 (PYY), pancreatic polypeptide (PP), and oxyntomodulin. Neural networks, such as the enteric nervous system (ENS) and vagus nerve also convey information within the gut-brain axis. Emerging evidence suggests the human gut microbiota, a complex ecosystem residing in the gastrointestinal tract (GIT), may influence weight-gain through several inter-dependent pathways including energy harvesting, short-chain fatty-acids (SCFA) signalling, behaviour modifications, controlling satiety and modulating inflammatory responses within the host. Hence, the gut-brain axis, the microbiota and the link between these elements and the role each plays in either promoting or regulating energy and thereby contributing to obesity will be explored in this review.

Surgery for Diabetes: Clinical and Mechanistic Aspects

According to the most recent publication by the Canadian Public Health Agency, obesity affects 25% of adults. In addition, there is a clear association between the recent rise in obesity and the increased prevalence of type 2 diabetes. Medical therapy for obesity has shown limited long-term effectiveness, and surgical treatment is now recognized by medical authorities as part of the armamentarium for the management of type 2 diabetes in severely obese patients. The current indications for obesity surgery and postoperative management are reviewed. The choice of surgery should balance expected benefits associated with weight loss (including remission rate of type 2 diabetes), side effects and the risks for early and long-term complications. Long-term outcomes of metabolic surgery for diabetes vary according to the type of surgery (ranging between 20% and 90% remission rates) and the underlying metabolic changes. Several controlled trials have been published in recent years confirming the superiority of metabolic surgery over medical treatment for the management of type 2 diabetes associated with severe obesity. Some of the known underlying mechanisms of action include a combination of caloric restriction, hormonal changes, decreased nutrient absorption and changes in bile acids, microbiota and incretins. Further research is needed to clarify the mechanistic changes associated with each surgical procedure and their respective long-term outcomes.

Gut as an emerging organ for the treatment of diabetes: focus on mechanism of action of bariatric and endoscopic interventions

Increasing worldwide prevalence of type 2 diabetes mellitus and its accompanying pathologies such as obesity, arterial hypertension and dyslipidemia represents one of the most important challenges of current medicine. Despite intensive efforts, high percentage of patients with type 2 diabetes does not achieve treatment goals and struggle with increasing body weight and poor glucose control. While novel classes of antidiabetic medications such as incretin-based therapies and gliflozins have some favorable characteristics compared to older antidiabetics, the only therapeutic option shown to substantially modify the progression of diabetes or to achieve its remission is bariatric surgery. Its efficacy in the treatment of diabetes is well established, but the exact underlying modes of action are still only partially described. They include restriction of food amount, enhanced passage of chymus into distal part of small intestine with subsequent modification of gastrointestinal hormones and bile acids secretion, neural mechanisms, changes in gut microbiota and many other possible mechanisms underscoring the importance of the gut in the regulation of glucose metabolism. In addition to bariatric surgery, less-invasive endoscopic methods based on the principles of bariatric surgery were introduced and showed promising results. This review highlights the role of the intestine in the regulation of glucose homeostasis focusing on the mechanisms of action of bariatric and especially endoscopic methods of the treatment of diabetes. A better understanding of these mechanisms may lead to less invasive endoscopic treatments of diabetes and obesity that may complement and widen current therapeutic options.

Upregulation of Ghrelin Gene Expression in the Excluded Stomach of Obese Women with Type 2 Diabetes After Roux-en-Y Gastric Bypass in the SURMetaGIT Study

BACKGROUND

Mechanisms of type 2 diabetes remission (T2Dr) after Roux-en-Y gastric bypass (RYGB) in obese patients appear to involve gastrointestinal hormones.

OBJECTIVE

The objective of this study is to explore changes in ghrelin plasma levels and ghrelin gastrointestinal gene expression (GHRL) after RYGB, and their relationships to T2Dr.

SETTING

In 20 obese women with T2D, before and 3 months after RYGB, we assessed GHRL expression by microarray and quantitative RT-PCR in gastrointestinal biopsy samples and plasma levels of ghrelin.

RESULTS

After RYGB, GHRL expression increased in the excluded stomach (p < 0.05) with no change in other gastrointestinal sites. There were no significant changes in ghrelin plasma levels and no correlations with T2Dr.

CONCLUSIONS

After RYGB, over-expression of GHRL gene occurs only in the excluded stomach with no correlation to T2Dr.

The Role of GLP-1 in the Metabolic Success of Bariatric Surgery

Two of the most popular bariatric procedures, vertical sleeve gastrectomy (VSG) and Roux-en-Y gastric bypass (RYGB), are commonly considered metabolic surgeries because they are thought to affect metabolism in a weight loss-independent manner. In support of this classification, improvements in glucose homeostasis, insulin sensitivity, and even discontinuation of type 2 diabetes mellitus (T2DM) medication can occur before substantial postoperative weight loss. The mechanisms that underlie this effect are unknown. However, one of the common findings after VSG and RYGB in both animal models and humans is the sharp postprandial rise in several gut peptides, including the incretin and satiety peptide glucagonlike peptide-1 (GLP-1). The increase in endogenous GLP-1 signaling has been considered a primary pathway leading to postsurgical weight loss and improvements in glucose metabolism. However, the degree to which GLP-1 and other gut peptides are responsible for the metabolic successes after bariatric surgery is continually debated. In this review we discuss the mechanisms underlying the increase in GLP-1 and its potential role in the metabolic improvements after bariatric surgery, including remission of T2DM. Understanding the role of changes in gut peptides, or lack thereof, will be crucial in understanding the critical factors necessary for the metabolic success of bariatric surgery.

MILEPOST Multicenter Randomized Controlled Trial: 12-Month Weight Loss and Satiety Outcomes After pose SM vs. Medical Therapy

BACKGROUND

Pose ^SM is an endolumenal weight-loss intervention in which suture anchors are placed endoscopically in the gastric fundus/distal gastric body. Observational studies of pose have shown safe, effective weight loss. Twelve-month results of a randomized controlled trial comparing weight loss and satiety after pose vs. conventional medical therapy are reported.

METHODS

Subjects with classes I-II obesity were randomized in a 3:1 ratio to pose or diet/exercise guidance only (control). Pose subjects received gastric fundus and distal body suture-anchor plications with diet/exercise counseling. Total body (%TBWL) and excess weight loss (%EWL) were assessed at 6 and 12 months. Analysis of covariance (ANCOVA) was used to analyze 12-month %TBWL. Satiety changes were assessed at 6 and 12 months.

RESULTS

From November 2013 to July 2014, 44 subjects were randomized (34, 77.3 % female; mean age, 38.3 ± 10.7 years; body mass index, 36.5 ± 3.4 kg/m²) to pose (n = 34) or control (n = 10) groups in three centers. Mean pose procedure time was 51.8 ± 14.5 min; pose subjects received a mean 8.8 ± 1.3 fundal and 4.2 ± 0.7 distal body plications. Twelve-month TBWL: pose, 13.0 % (EWL, 45.0 %), n = 30 vs. control group, 5.3 % (18.1 %), n = 9; significant mean difference, 7.7 % (95 % CI 2.2, 13.2; p < 0.01). Pose subjects showed significant reductions in satiety parameters (p < 0.001); controls experienced reduced caloric intake and satiety volume (p < 0.05). No serious device- or procedure-related adverse events occurred.

CONCLUSIONS

In a randomized controlled trial at 12 months, pose-treated subjects had significantly greater weight loss than those treated with diet/exercise guidance alone. At 6 and 12 months, pose subjects showed significant reduction in satiety parameters.

STUDY REGISTRATION

clinicaltrials.gov identifier # NCT01843231.

Potential Hormone Mechanisms of Bariatric Surgery

PURPOSE OF REVIEW

In recent years, the role of the gastrointestinal (GI) tract in energy homeostasis through modulation of the digestion and absorption of carbohydrates and the production of incretin hormones is well recognized.

RECENT FINDINGS

Bariatric surgery for obesity has been a very effective method in substantially improving weight, and numerous studies have focused on intestinal adaptation after bariatric procedures. A number of structural and functional changes in the GI tract have been reported postsurgery, which could be responsible for the altered hormonal responses. Furthermore, the change in food absorption rate and the intestinal regions exposed to carbohydrates may affect blood glucose response. This review hopes to give new insights into the direct role of gut hormones, by summarising the metabolic effects of bariatric surgery.

Bariatric Surgery for Adolescents with Type 2 Diabetes: an Emerging Therapeutic Strategy

PURPOSE OF REVIEW

Type 2 diabetes (T2D) is a growing public health problem in youth, but conventional treatments are often insufficient to treat this disease and its comorbidities. We review evidence supporting an emerging role for bariatric surgery as a treatment for adolescent T2D.

RECENT FINDINGS

Paralleling what has been seen in adult patients, bariatric surgery dramatically improves glycemic control in patients with T2D. In fact, remission of T2D has been observed in as many as 95-100% of adolescents with diabetes after bariatric surgery, particularly vertical sleeve gastrectomy (VSG) and Roux-en-Y gastric bypass (RYGB) surgery. This striking outcome may be due to both weight-dependent- and weight-independent factors, and recent studies suggest that T2D-related comorbidities may also improve after surgery. Bariatric surgery including RYGB and VSG is a powerful therapeutic option for obese adolescents with T2D. Benefits must be weighed against risk for postoperative complications such as nutritional deficiencies, but earlier surgical intervention might lead to more complete metabolic remission in obese patients with T2D.

A prospective 4-year study of insulin resistance and adipokines in morbidly obese diabetic and non-diabetic patients after gastric banding

Introduction

There are insufficient data regarding the changes in adipokine levels after laparoscopic adjustable gastric banding (LAGB) in diabetic and non-diabetic patients and their effects on insulin resistance and type 2 diabetes remission.

Aim

To assess leptin, adiponectin, and insulin resistance changes after LAGB in diabetic and non-diabetic morbidly obese patients.

Material and methods

One hundred and three patients (37 with and 66 without type 2 diabetes) underwent LAGB from January 2009 to January 2010. Glycated hemoglobin, insulin, adipokine levels and insulin resistance were evaluated preoperatively, and 1 and 4 years after LAGB.

Results

The mean patient age was 45.9 ±11.7 years and mean preoperative body mass index was 47.5 ±7.3 kg/m². A total of 80 of 103 patients (77.6%) completed the 4-year follow-up. After 4 years the mean excess weight loss was 38.8% and 39.5% in diabetic and non-diabetic patients respectively. Leptin levels decreased significantly in both groups at 1 year, but after 4 years this was noted only in non-diabetic patients. After 1 year adiponectin levels increased significantly only in non-diabetic patients (p = 0.003) and remained almost the same at 4 years. A significant decrease in insulin resistance was noted in both groups 1 year after LAGB and diabetes remission was observed in 23 (62.1%) patients. There was a negative correlation between preoperative insulin resistance and adiponectin levels throughout the follow-up period. Leptin levels positively correlated with BMI throughout the study period (baseline r = 0.45; p < 0.001; after 1 year r = 0.71; p < 0.001; after 4 years r = 0.68; p < 0.001). There was no significant correlation between leptin and adiponectin concentrations preoperatively or after 1 year; however, at 4 years it was significant (r = 0.27; p < 0.02).

Conclusions

The most significant metabolic changes occurred within 1 year after LAGB. The 4-year follow-up revealed stabilization in metabolic indices rather than significant improvement.

Liver Transplantation and Bariatric Surgery: Best Approach

Obesity has become increasingly prevalent, and the number of obese patients in need of liver transplant is expected to continue to increase. In addition, liver disease due to nonalcoholic fatty liver disease is expected to become the leading cause of liver transplantation in the near future. However, obesity remains a relative contraindication in liver transplant. New strategies in managing this patient population are clearly needed. To this end, the authors review the current literature on the efficacy of bariatric surgery in the setting of liver transplantation in obese patients.

Control of Food Intake by Gastrointestinal Peptides: Mechanisms of Action and Possible Modulation in the Treatment of Obesity

This review focuses on the control of appetite by food intake-regulatory peptides secreted from the gastrointestinal tract, namely cholecystokinin, glucagon-like peptide 1, peptide YY, ghrelin, and the recently discovered nesfatin-1 via the gut-brain axis. Additionally, we describe the impact of external factors such as intake of different nutrients or stress on the secretion of gastrointestinal peptides. Finally, we highlight possible conservative—physical activity and pharmacotherapy—treatment strategies for obesity as well as surgical techniques such as deep brain stimulation and bariatric surgery also altering these peptidergic pathways.

Comparison of consumption behavior and appetite sensations among patients with type 2 diabetes mellitus after bariatric surgery

BACKGROUND

The promising postsurgical weight loss and remission of type 2 diabetes (T2D) from bariatric surgery can be attributed to modified eating physiology after surgical procedures. We sought to investigate the changes in the parameters of consumption behaviors and appetite sensations induced by a mixed meal tolerance test, and to correlate these alterations with age, body mass index, C-peptide levels, and duration of T2D 1 year after bariatric surgery.

METHODS

A total of 16 obese patients with T2D who underwent mini-gastric bypass (GB) and 16 patients who underwent sleeve gastrectomy (SG) were enrolled in this study and evaluated using a mixed meal tolerance test one year after surgery. A visual analogue scale was used for scoring appetite sensation at different time points. The area under the curve (AUC) and the incremental or decremental AUC (ΔAUC) were compared between the two groups.

RESULTS

One year after surgery, a decreasing trend in the consumption time was observed in the GB group compared to the SG group, while the duration of T2D before surgery was negatively correlated with the post-operative consumed time in those after GB. Patients who underwent GB had significantly higher fasting scores for fullness and desire to eat, higher AUC_0'-180' of scores for desire to eat, as well as more effective post-meal suppression of hunger and desire to eat compared with those undergoing SG one year after surgery. Post-operative C-peptide levels were negatively correlated with ΔAUC_0'-180' for hunger and ΔAUC_0'-180' for desire to eat in the GB group, while negatively correlated with ΔAUC_0'-180' for fullness in the SG group.

DISCUSSION

Patients with T2D after either GB or SG exhibit distinct nutrient-induced consumption behaviors and appetite sensations post-operatively, which may account for the differential effects on weight loss and glycemic control after different surgery.

Metabolic improvements following Roux-en-Y surgery assessed by solid meal test in subjects with short duration type 2 diabetes

BACKGROUND

Glucose homeostasis improves within days following Roux-en-Y gastric bypass (RYGB) surgery. The dynamic metabolic response to caloric intake following RYGB has been assessed using liquid mixed meal tolerance tests (MMTT). Few studies have evaluated the glycemic and hormonal response to a solid mixed meal in subjects with diabetes prior to, and within the first month following RYGB.

METHODS

Seventeen women with type 2 diabetes of less than 5 years duration participated. Fasting measures of glucose homeostasis, lipids and gut hormones were obtained pre- and post-surgery. MMTT utilizing a solid 4 oz chocolate pudding performed pre-, 2 and 4 weeks post-surgery. Metabolic response to 4 and 2 oz MMTT assessed in five diabetic subjects not undergoing surgery.

RESULTS

Significant reductions in fasting glucose and insulin at 3 days, and in fasting betatrophin, triglycerides and total cholesterol at 2 weeks post-surgery. Hepatic insulin clearance was greater at 3 days post-surgery. Subjects exhibited less hunger and greater feelings of fullness and satisfaction during the MMTT while consuming 52.9 ± 6.5% and 51.0 ± 6.5% of the meal at 2 and 4 weeks post-surgery respectively. At 2 weeks post-surgery, glucose and insulin response to MMTT were improved, with greater GLP-1 and PYY secretion. Improved response to solid MMTT not replicated by consumption of smaller pudding volume in diabetic non-surgical subjects.

CONCLUSIONS

With a test meal of size and composition representative of the routine diet of post-RYGB subjects, improved glycemic and gut hormone responses occur which cannot be replicated by reducing the size of the MMTT in diabetic subjects not undergoing surgery.

TRIAL REGISTRATION

Clinical Trials.gov Identifier: NCT00957957 August 11, 2009.

FGF 19 and Bile Acids Increase Following Roux-en-Y Gastric Bypass but Not After Medical Management in Patients with Type 2 Diabetes

BACKGROUND

This study aims to quantify changes in fibroblast growth factor 19 (FGF19) and bile acids (BAs) in patients with uncontrolled type 2 diabetes randomized to Roux-en-Y gastric bypass (RYGB) vs intensive medical management (IMM) and matched for similar reduction in HbA1c after 1 year of treatment.

METHODS

Blood samples were drawn from patients who underwent a test meal challenge before and 1 year after IMM (n = 15) or RYGB (n = 15).

RESULTS

Mean HbA1c decreased from 9.7 to 6.4% after RYGB and from 9.1 to 6.1% in the IMM group. At 12 months, the number of diabetes medications used per subject in the RYGB group (2.5 ± 0.5) was less than in the IMM group (4.6 ± 0.3). After RYGB, FGF19 increased in the fasted (93 ± 15 to 152 ± 19 pg/ml; P = 0.008) and postprandial states (area under the curve (AUC), 10.8 ± 1.9 to 23.4 ± 4.1 pg × h/ml × 10(3); P = 0.006) but remained unchanged following IMM. BAs increased after RYGB (AUC ×10(3), 6.63 ± 1.3 to 15.16 ± 2.56 μM × h; P = 0.003) and decreased after IMM (AUC ×10(3), 8.22 ± 1.24 to 5.70 ± 0.70; P = 0.01). No changes were observed in the ratio of 12α-hydroxylated/non-12α-hyroxylated BAs. Following RYGB, FGF19 AUC correlated with BAs (r = 0.54, P = 0.04) and trended negatively with HbA1c (r = -0.44; P = 0.09); these associations were not observed after IMM.

CONCLUSIONS

BA and FGF19 levels increased after RYGB but not after IMM in subjects who achieved similar improvement in glycemic control. Further studies are necessary to determine whether these hormonal changes facilitate improved glucose homeostasis.

Early effects of Roux-en-Y gastric bypass on peptides and hormones involved in the control of energy balance

INTRODUCTION

Body weight varies depending on the prevailing direction of environmental pressures; however, physiological factors also play a significant role in the control of body weight. The aim of the present study was to assess the impact of Roux-en-Y gastric bypass (RYGB) on hormones and peptides involved in the control of energy balance and their possible implications in appetite/satiety.

METHODS

The sample included 39 individuals with extreme obesity (37 women and two men) who underwent RYGB. Anthropometric and biochemical markers were collected before surgery and 6 months after RYGB.

RESULTS

The BMI decreased from 44.3±6.4 to 31.7±5.7 kg/m (P<0.001) at the sixth month. Percentage of excess weight lost was 63.2±25.0%. Leptin and glucose levels decreased significantly 6 months after RYGB (P<0.001). Interestingly, a significant correlation was confirmed between the anorexigenic gut hormone peptide YY (PYY) and the central anorexigenic mediator α-melanocyte-stimulating hormone after 6 months of RYGB (r=0.35, P=0.004). In contrast, PYY concentrations were correlated negatively with BMI (r=-0.34, P=0.002).

CONCLUSION

In the present investigation, it was found that there is a relationship between α-melanocyte-stimulating hormone and PYY concentrations, and it supports the role of the PYY to POMC signal in appetite regulation after RYGB.

Lipocalin-type prostaglandin D2 synthase (L-PGDS) modulates beneficial metabolic effects of vertical sleeve gastrectomy

BACKGROUND

Vertical sleeve gastrectomy (VSG) ameliorates metabolic complications in obese and diabetic patients through unknown mechanisms.

OBJECTIVE

The objective of this study was to investigate the role of lipocalin-type prostaglandin D₂ synthase (L-PGDS) in glucose regulation in response to VSG using L-PGDS knock-out (KO), knock-in (KI), and C57BL/6 (wild type) mice.

SETTING

Winthrop University Hospital Research Institute.

METHODS

Animals were divided into 6 groups: L-PGDS KO sham/VSG (n = 5), L-PGDS KI sham/VSG (n = 5), and C57BL/6 (wild type) sham/VSG (n = 5). Related parameters were measured in fasting animals after 10 weeks.

RESULTS

Our intraperitoneal glucose tolerance tests and homeostatic model assessment insulin resistance results showed significant glycemic improvement 10 weeks post-VSG in both C57BL/6 and KI groups compared with the sham group. In contrast, the KO group developed glucose intolerance and insulin resistance similar to or greater than the sham group 10 weeks post-VSG. Interestingly, weight gain was insignificant 10 weeks post-VSG in all the groups and even trended higher in the KO group compared with sham. Peptide YY levels in the KO group post-VSG were slightly increased but significantly less than other groups. Similarly, the KO group showed significantly less leptin sensitivity in response to VSG compared with the KI group. Total cholesterol level remained unchanged in all groups irrespective of sham or surgery but interestingly, the KO group had significantly higher cholesterol levels. In parallel, adipocyte size was also found to be significantly increased in the KO group post-VSG compared with the sham group.

CONCLUSION

Our findings propose that L-PGDS plays an important role in the beneficial metabolic effects observed after VSG.

Type 2 Diabetes Remission Rates After Laparoscopic Gastric Bypass and Gastric Banding: Results of the Longitudinal Assessment of Bariatric Surgery Study

OBJECTIVE

The goals of this study were to determine baseline and postbariatric surgical characteristics associated with type 2 diabetes remission and if, after controlling for differences in weight loss, diabetes remission was greater after Roux-en-Y gastric bypass (RYGBP) than laparoscopic gastric banding (LAGB).

RESEARCH DESIGN AND METHODS

An observational cohort of obese participants was studied using generalized linear mixed models to examine the associations of bariatric surgery type and diabetes remission rates for up to 3 years. Of 2,458 obese participants enrolled, 1,868 (76%) had complete data to assess diabetes status at both baseline and at least one follow-up visit. Of these, 627 participants (34%) were classified with diabetes: 466 underwent RYGBP and 140 underwent LAGB.

RESULTS

After 3 years, 68.7% of RYGBP and 30.2% of LAGB participants were in diabetes remission. Baseline factors associated with diabetes remission included a lower weight for LAGB, greater fasting C-peptide, lower leptin-to-fat mass ratio for RYGBP, and a lower hemoglobin A1c without need for insulin for both procedures. After both procedures, greater postsurgical weight loss was associated with remission. However, even after controlling for differences in amount of weight lost, relative diabetes remission rates remained nearly twofold higher after RYGBP than LAGB.

CONCLUSIONS

Diabetes remission up to 3 years after RYGBP and LAGB was proportionally higher with increasing postsurgical weight loss. However, the nearly twofold greater weight loss-adjusted likelihood of diabetes remission in subjects undergoing RYGBP than LAGB suggests unique mechanisms contributing to improved glucose metabolism beyond weight loss after RYGBP.

Jejunal administration of glucose enhances acyl ghrelin suppression in obese humans

Ghrelin is a gastric hormone that stimulates hunger and worsens glucose metabolism. Circulating ghrelin is decreased after Roux-en-Y gastric bypass (RYGB) surgery; however, the mechanism(s) underlying this change is unknown. We tested the hypothesis that jejunal nutrient exposure plays a significant role in ghrelin suppression after RYGB. Feeding tubes were placed in the stomach or jejunum in 13 obese subjects to simulate pre-RYGB or post-RYGB glucose exposure to the gastrointestinal (GI) tract, respectively, without the confounding effects of caloric restriction, weight loss, and surgical stress. On separate study days, the plasma glucose curves obtained with either gastric or jejunal administration of glucose were replicated with intravenous (iv) infusions of glucose. These "isoglycemic clamps" enabled us to determine the contribution of the GI tract and postabsorptive plasma glucose to acyl ghrelin suppression. Plasma acyl ghrelin levels were suppressed to a greater degree with jejunal glucose administration compared with gastric glucose administration (P < 0.05). Jejunal administration of glucose also resulted in a greater suppression of acyl ghrelin than the corresponding isoglycemic glucose infusion (P ≤ 0.01). However, gastric and isoglycemic iv glucose infusions resulted in similar degrees of acyl ghrelin suppression (P > 0.05). Direct exposure of the proximal jejunum to glucose increases acyl ghrelin suppression independent of circulating glucose levels. The enhanced suppression of acyl ghrelin after RYGB may be due to a nutrient-initiated signal in the jejunum that regulates ghrelin secretion.

A prospective study of appetite and food craving in 30 patients with Cushing's disease

CONTEXT

Glucocorticoid (GC) exposure increases food intake, but the mechanisms in humans are not known. Investigation of appetite and food craving has not been done in patients with chronic GC exposure due to Cushing's disease (CD), either before or after treatment, and could provide insight into mechanisms of food intake and obesity in these patients.

PURPOSE

To examine whether surgical remission of CD changes appetite (prospective consumption, hunger, satisfaction, and fullness) and food cravings (sweet, salty, fatty, and savory); and to identify predictors of appetite and craving in CD remission.

METHODS

30 CD patients, mean age 40.0 years (range 17-70), mean BMI 32.3 ± 6.4, were prospectively studied before and at a mean of 17.4 mo. after remission. At each visit fasting and post-test meal (50% carbohydrate, 35% protein, 15% fat) appetite and craving scores were assessed.

RESULTS

Remission decreased prospective consumption, sweet and savory craving (p < 0.05), but did not change hunger, satisfaction, fullness, or fat craving, despite decreases in BMI and fat mass. In CD remission, serum cortisol predicted lower satisfaction and fullness, and masses of abdominal fat depots predicted higher hunger and consumption (p < 0.05).

CONCLUSIONS

Chronic GC exposure in CD patients may stimulate the drive to eat by enhancing craving, rather than regulating the sensation of hunger. Continued alterations in appetite regulation due to abdominal fat mass and circulating cortisol could play a role in the cardiovascular and metabolic risk that has been reported in CD patients despite remission.

The effect of bariatric surgery on gastrointestinal and pancreatic peptide hormones

Bariatric surgery for obesity has proved to be an extremely effective method of promoting long-term weight reduction with additional beneficial metabolic effects, such as improved glucose tolerance and remission of type 2 diabetes. A range of bariatric procedures are in common use, including gastric banding, sleeve gastrectomy and the Roux-en-Y gastric bypass. Although the mechanisms underlying the efficacy of bariatric surgery are unclear, gastrointestinal and pancreatic peptides are thought to play an important role. The aim of this review is to summarise the effects of different bariatric surgery procedures upon gastrointestinal and pancreatic peptides, including ghrelin, gastrin, cholecystokinin (CCK), glucose-dependent insulinotropic hormone (GIP), glucagon-like peptide 1 (GLP-1), peptide YY (PYY), oxyntomodulin, insulin, glucagon and somatostatin.