Ghrelin levels could be involved in the improvement of insulin resistance after bariatric surgery

The effect of weight loss on hypothalamus structure and function in obese individuals: a systematic review and meta-analysis

INTRODUCTION

Obesity presents with structural and functional hypothalamic dysfunction. However, it is unclear whether weight loss can lead to hypothalamic changes. We therefore aimed to conduct a systematic review and meta-analysis to determine the effect of body mass reduction in obese individuals on hypothalamic structure and function.

METHODS

PubMed, Embase and Cochrane databases were searched for studies that reported the change in hypothalamic structure and function after weight loss. Qualitative and quantitative analyses were performed on magnetic resonance imaging techniques, medio-basal hypothalamus T2-relaxation time, blood oxygen level dependent (BOLD) contrast, voxel-based morphometry (VBM) and biomarkers including glucose, insulin, leptin, ghrelin and inflammatory markers of interleukins. Mean differences between pre- and post-weight loss and 95% confidence intervals (CIs) were pooled using random-effects models.

RESULTS

Thirteen pre-post studies were included, of which six accounted for the meta-analysis. Studies showed a favorable decrease in T2-relaxation time (n = 1), favorable change in hypothalamic activity after weight loss on BOLD contrast (n = 4), with higher peak activities after surgical weight loss (n = 2). No differences were found in the gray matter density of the hypothalamus on VBM (n = 1). Pooled mean differences between pre- and post-surgical weight loss revealed a decrease of 8.53 mg/dl (95% CI: 5.17, 11.9) in glucose, 7.73 pmol/l (95% CI: 5.07, 10.4) in insulin, 15.5 ng/ml (95% CI: 9.40, 21.6) in leptin, 142.9 pg/ml (95% CI: 79.0, 206.8) in ghrelin and 9.43 pg/ml (95% CI: -6.89, 25.7) in IL-6 level.

CONCLUSIONS

Our study showed weight reduction in obesity led to limited structural change and significant functional changes in the hypothalamus.

Association of postoperative dietary macronutrient content and quality with total weight loss and fat-free mass loss at midterm after sleeve gastrectomy

OBJECTIVES

This study aimed to investigate the associations of macronutrient quantities and qualities with percentage total weight loss and percentage of fat-free mass loss relative to total weight loss in adults undergoing sleeve gastrectomy.

METHODS

This cross-sectional study included 146 patients on postoperative time since sleeve gastrectomy of 2 to 4 y. Diet was assessed using a food frequency questionnaire. Macronutrient quality index, carbohydrate quality index, fat quality index, and healthy plate protein quality index were calculated. The associations of dietary variables with percentage total weight loss and percentage of fat-free mass loss relative to total weight loss were determined using linear regression. Logistic regression was used to estimate the odds of non-response (percentage total weight loss < 25%) and excessive fat-free mass loss (percentage of fat-free mass loss relative to total weight loss > 28%) based on dietary intakes.

RESULTS

Forty-six (31.5%) were non-responders, and 49 (33.6%) experienced excessive fat-free mass loss. The fully adjusted model showed a 0.75 decrease in percentage total weight loss per 5% carbohydrate increase (95% CI, -1.45 to -0.05). The odds of non-response were 53% lower per 5% increase in protein (95% CI, 0.23-0.94). Each 5-g higher intake of fat was associated with 0.29 higher percentage of fat-free mass loss relative to total weight loss (95% CI, 0.03-0.55). The odds of excessive fat-free mass loss were reduced by 5% per gram of fiber intake (95% CI, 0.90-0.99). Each 5% increment in energy intake from protein that was isocalorically substituted for either carbohydrate or fat was associated with lower odds of nonresponse. Macronutrient quality indices had no significant associations.

CONCLUSIONS

Adherence to a high-protein, high-fiber diet after sleeve gastrectomy may enhance surgical success by improving total weight loss and preventing excessive fat-free mass loss.

State of art on the mechanisms of laparoscopic sleeve gastrectomy in treating type 2 diabetes mellitus

Obesity and type-2 diabetes mellitus (T2DM) are metabolic disorders. Obesity increases the risk of T2DM, and as obesity is becoming increasingly common, more individuals suffer from T2DM, which poses a considerable burden on health systems. Traditionally, pharmaceutical therapy together with lifestyle changes is used to treat obesity and T2DM to decrease the incidence of comorbidities and all-cause mortality and to increase life expectancy. Bariatric surgery is increasingly replacing other forms of treatment of morbid obesity, especially in patients with refractory obesity, owing to its many benefits including good long-term outcomes and almost no weight regain. The bariatric surgery options have markedly changed recently, and laparoscopic sleeve gastrectomy (LSG) is gradually gaining popularity. LSG has become an effective and safe treatment for type-2 diabetes and morbid obesity, with a high cost-benefit ratio. Here, we review the me-chanism associated with LSG treatment of T2DM, and we discuss clinical studies and animal experiments with regard to gastrointestinal hormones, gut microbiota, bile acids, and adipokines to clarify current treatment modalities for patients with obesity and T2DM.

Somatostatin: From a supporting actor to the protagonist to explain the long-term effect of sleeve gastrectomy on glucose metabolism

BACKGROUND

Bariatric/metabolic surgery has become the most effective treatment against type 2 Diabetes mellitus (T2DM). The role of many gastrointestinal hormones in T2DM has been proposed, but the pathophysiological models described vary greatly depending on the anatomical rearrangements after surgery. We focus on somatostatin as a common factor in two of the most commonly performed surgical procedures in a healthy rodent model. We performed sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) and also an experimental surgery without gastric involvement (intestinal resection of 50 % jejunum-ileum portion -IR50 %).

METHODS

We used five groups of Wistar rats: fasting control, sham-operated, SG-operated, RYGB-operated and IR50-operated. We analysed several parameters 4 and 23 weeks after surgery: plasma SST-14/28 fractions, plasma glucose, insulin release and SST-producing cell expression in the duodenum and pancreatic islets.

RESULTS

Numerous SST-producing cells in the duodenum but a low number in the pancreas and a long-term loss of glucose tolerance were observed in SG and RYGB animals. Additionally, a high plasma SST-28 fraction was found in animals after SG but not after RYGB. Finally, IR50 animals showed no differences versus controls.

CONCLUSIONS

In our SG model the amplitude of insulin response after metabolic surgeries, is mediated by SST-28 plasma levels derived from the proportional compensatory effect of gastric SST-producing tissue ablation. In addition, a strong compensatory response to the surgical loss of gastric SST-producing cells, leads to long-term loss of insulin production after SG but not in the others.

The role of the gastric fundus in glycemic control

PURPOSE

Ghrelin, one of the most studied gut hormones, is mainly produced by the gastric fundus. Abundant evidence exists from preclinical and clinical studies underlining its contribution to glucose regulation. In the following narrative review, the role of the gastric fundus in glucose regulation is summarized and we investigate whether its resection enhances glycemic control.

METHODS

An electronic search was conducted in the PubMed® database and in Google Scholar® using a combination of medical subject headings (MeSH). We examined types of metabolic surgery, including, in particular, gastric fundus resection, either as part of laparoscopic sleeve gastrectomy (LSG) or modified laparoscopic gastric bypass with fundus resection (LRYGBP + FR), and the contribution of ghrelin reduction to glucose regulation.

RESULTS

Fourteen human studies were judged to be eligible and included in this narrative review. Reduction of ghrelin levels after fundus resection might be related to early glycemic improvement before significant weight loss is achieved. Long-term data regarding the role of ghrelin reduction in glucose homeostasis are sparse.

CONCLUSION

The exact role of ghrelin in achieving glycemic control is still ambiguous. Data from human studies reveal a potential contribution of ghrelin reduction to early glycemic improvement, although further well-designed studies are needed.

Retrospective Comparison of SADI-S Versus RYGB in Chinese with Diabetes and BMI< 35kg/m2: a Propensity Score Adjustment Analysis

BACKGROUND

As a modification of the duodenal switch (DS), single-anastomosis duodenal-ileal bypass with sleeve gastrectomy (SADI-S) has recently become very popular and is successful for weight loss and T2DM remission. However, current studies have been mostly aimed at patients with severe obesity.

OBJECTIVES

In this study, we firstly compare primary SADI-S to the Roux-en-Y gastric bypass (RYGB) in Chinese with diabetes and BMI< 35 kg/m².

METHODS

Using a propensity score (PS) matching analysis, we analyzed all patients with diabetes and BMI< 35 kg/m² who underwent primary SADI-S or RYGB. All surgeries were conducted by a single surgeon at a Chinese center from June 2017 to January 2019.

RESULTS

Twenty-six patients who underwent SADI-S and 65 patients who underwent RYGB were included in our analysis. Of these, 26 (100%) of patients in the SADI-S group and 43 (66%) of patients in the RYGB group completed the 24-month follow-up. No severe perioperative complication was observed in either group. There was a statistically higher percentage of total weight loss with SADI-S at the 2-year follow-up when compared to RYGB (p = 0.017 after PS correction). After PS adjustment, 76.5% of patients in the SADI-S group and 82.4% of patients in the RYGB group achieved complete remission of T2DM (p = 1.000). Nutritional outcomes were similar in the two groups.

CONCLUSION

In Chinese with diabetes and BMI< 35 kg/m², with comparable T2DM remission and nutritional outcomes, primary SADI-S allows for better weight loss than RYGB. Compared with RYGB, SADI-S is also a safe, effective, and feasible treatment for these patients.

Long-Term Changes in Leptin, Chemerin, and Ghrelin Levels Following Roux-en-Y Gastric Bypass and Laparoscopic Sleeve Gastrectomy

AIM

Published reports showed conflicting results regarding the sustained alterations in leptin, chemerin, and ghrelin concenratios after metabolic surgery. Therefore, we performed the present work to contrast the alterations in leptin, chemerin, and ghrelin levels one year after Roux-en-Y gastric bypass (RYGB) versus laparoscopic sleeve gastrectomy (LSG).

METHODS

The present research is a prospective, comparative one that followed 100 cases for whom RYGB or LSG was done. We assessed the serum values of adiposity-associated mediators, including adipokcytokines (leptin and active chemerin) and gastrointestinal hormones (total ghrelin). The primary outcome in the present study was the alterations in leptin, chemerin, and ghrelin values at 12 months after RYGB and LSG.

RESULTS

The serum leptin level decreased significantly in the LSG group with a mean change of - 170.8 ± 29.4 ng/mL (p < 0.001). Similarly, the serum leptin concentration decreased significantly in the RYGB group, with a mean change of - 165.42 ± 53.4 (p < 0.001). In addition, the mean reduction in baseline chemerin levels 12 months after the operation was considerable in the LSG cohort (- 23.24 ± 9.5 ng/mL) and RYGB group (- 22.12 ± 15.9 ng/mL). The ghrelin values demonstrated a notable reduction in the LSG cohort (- 0.083 ± 0.11 pg/mL) and RYGB group (- 0.068 ± 0.097 pg/mL). However, the changes in the three hormones were not substantially different between both groups (p > 0.05).

CONCLUSION

Both RYGB and LSG result in a considerable, comparable decrease in the postoperative serum concentrations of leptin, chemerin, and ghrelin.

Oleic acid restores the rhythmicity of the disrupted circadian rhythm found in gastrointestinal explants from patients with morbid obesity

BACKGROUND & AIMS

We investigated whether oleic acid (OA), one of the main components of the Mediterranean diet, participates in the regulation of the intestinal circadian rhythm in patients with morbid obesity.

METHODS

Stomach and jejunum explants from patients with morbid obesity were incubated with oleic acid to analyze the regulation of clock genes.

RESULTS

Stomach explants showed an altered circadian rhythm in CLOCK, BMAL1, REVERBα, CRY1, and CRY2, and an absence in PER1, PER2, PER3 and ghrelin (p > 0.05). OA led to the emergence of rhythmicity in PER1, PER2, PER3 and ghrelin (p < 0.05). Jejunum explants showed an altered circadian rhythm in CLOCK, BMAL1, PER1 and PER3, and an absence in PER2, REVERBα, CRY1, CRY2 and GLP1 (p > 0.05). OA led to the emergence of rhythmicity in PER2, REVERBα, CRY1 and GLP1 (p < 0.05), but not in CRY2 (p > 0.05). OA restored the rhythmicity of acrophase and increased the amplitude for most of the genes studied in stomach and jejunum explants. OA placed PER1, PER2, PER3, REVERBα, CRY1 and CRY2 in antiphase with regard to CLOCK and BMAL1.

CONCLUSIONS

There is an alteration in circadian rhythm in stomach and jejunum explants in morbid obesity. OA restored the rhythmicity of the genes related with circadian rhythm, ghrelin and GLP1, although with slight differences between tissues, which could determine a different behaviour of the explants from jejunum and stomach in obesity.

Plasma ghrelin, adiponectin and leptin levels in obese rats with type 2 diabetes mellitus after sleeve gastrectomy and gastric plication

The prevalence of obesity has increased in recent decades and has become a public health problem. In obesity patients the metabolism of almost all adipokines is markedly dysregulated. Studies regarding levels of ghrelin, leptin, and adiponectin after bariatric surgery reveal contradictory results. The purpose of the present study was to analyze modification of body weight and plasma levels of fasting glucose, ghrelin, adiponectin and leptin, in obese rats with T2DM after sleeve gastrectomy (SG), gastric plication (GP) and sham-operated (SO). Eighteen specimens where randomized to three weight-matched groups: Group SG underwent sleeve gastrectomy (n=6), group GP underwent gastric plication (n=6) and the control group SO underwent sham surgery (n=6). Upon surgery a normal rat chow diet (Bio-Serv^® product no. F4031) was fed to the rats until the end of the experiment. Additional blood samples were harvested after 4 weeks. The results revealed that body mass decreased in the SG (783.17±101.39 vs. 658.33±86.57 g; P<0.0001) and the GP (781.33±103.12 vs. 702.33±84.06 g; P=0.004) rats after surgery. There were significant lower fasting glucose levels at 4 weeks postoperative in the SG group compared to the SO group (83.1±12.81 vs. 104.5±9.81 mg/dl; P=0.016). The same trend was observed in the GP group vs. the SO group (86.7±11.43 vs. 104.5±9.81 mg/dl; P=0.026). There was no difference regarding mean glucose levels between the SG group compared to the GP group (P>0.05). Plasma acylated ghrelin and leptin levels decreased four weeks after surgery compared to preoperative levels, while adiponectin levels increased four weeks after surgery in the SG and GP groups, respectively. The present study revealed that plasma glucose levels, ghrelin and leptin levels decreased after SG and GP, while adiponectin levels improved. This suggests that there may be hormonal contribution in weight loss.

Impact of Metabolic Surgery on Type-2 Diabetes Remission

Diabetes Mellitus is characterized by numerous metabolic disorders, which have in common the serum elevation of glucose, caused for a pancreatic malfunction in insulin secretion and / or its action. It is a non-communicable disease, considered major public health problems and generalized growth worldwide, being a chronic disease, which can generate a high treatment cost. Metabolic surgery is a safe treatment, regulated by the Federal Council of Medicine and useful in treating people with BMI over 30 years of age, who are unable to control pathologies associated with obesity, primarily type 2 diabetes. The general objective of this study is to understand through a literature review the main impacts of metabolic surgery about the remission of DM 2. This present study it is an exploratory and descriptive study carried out through a literature review. Data were collected through research in virtual health databases, at the Virtual Health Library - VHL, Latin American and Caribbean Health Sciences Information System, LILACS, National Library of Medicine - MEDLINE, Scielo, USP database, PUBMED theses and books. Metabolic surgery proof be a good and effective treatment for having and maintaining good weight loss, as well as a significant clinical and metabolic improvement that extends beyond weight loss. Metabolic surgery is a satisfactory way of achieving long-term weight reduction in obese individuals, increasing survival for these patients. Obese patients with DM2 have a long-term remission of DM2 after bariatric / metabolic surgery. Therefore, it concludes that such procedure is effective in the treatment of the disease and other diseases associated with obesity.

Revisiting the Ghrelin Changes Following Bariatric and Metabolic Surgery

Since the description of ghrelin in 1999, several studies have dug into the effects of this hormone and its relationship with bariatric surgery. While some aspects are still unresolved, a clear connection between ghrelin and the changes after metabolic surgery have been established. Besides weight loss, a significant amelioration in obesity-related comorbidities following surgery has also been reported. These changes in patients occur in the early postoperative period, before the weight loss appears, so that amelioration may be mainly due to hormonal changes. The purpose of this review is to go through the current body of knowledge of ghrelin's physiology, as well as to update and clarify the changes that take place in ghrelin concentrations following bariatric/metabolic surgery together with their potential consolidation to outcomes.

Remission of Type 2 Diabetes and Sleeve Gastrectomy in Morbid Obesity: a Comparative Systematic Review and Meta-analysis

BACKGROUND

The sleeve gastrectomy (SG) has gained popularity which has resulted in a rising number of patients with T2DM to undergo this procedure. This systematic review and meta-analysis aimed to compare the long-term effects of SG on T2DM remission with remission seen after Roux-en-Y gastric bypass (RYGB) or gastric banding (GB).

METHODS

A literature search was performed in PubMed and Cochrane Library using the following search terms: 'sleeve gastrectomy', 'diabetes', 'gastric bypass' and 'gastric banding'. Studies published between January 2000 and April 2018, and with following inclusion criteria were selected for this review: BMI ≥ 35 kg/m2, age ≥ 18 years, follow-up ≥ 1 year, T2DM. Data was statistically analysed using a random-effects model and results were expressed as odds ratio with 95% confidence interval.

RESULTS

After exclusion, 35 out of an initial 748 studies, consisting of 18 138 T2DM patients, remained for inclusion. Of these patients, 2480 underwent a SG. The remaining patients underwent a RYGB (n = 10,597) or GB (n = 5061). One year postoperatively, SG patients reached significantly (OR 0.71, p = 0.003) less T2DM remission than RYGB. After stratifying for different criteria for remission, RYGB still tended to result in higher remission rates, but the difference was not statistically significant. Beyond 1 year of follow-up, the difference between RYGB and SG in terms of T2DM remission decreased. SG was superior to the GB (OR 2.17, p = 0.001) after 1 year of follow-up.

CONCLUSION

This review demonstrates important remission of T2DM following SG. Nevertheless, as remission was significantly more often observed following RYGB surgery, the latter procedure remains the gold standard for reaching T2DM remission in patients with concurrent obesity.

[Ghrelin deficiency in patients with type 2 diabetes: the relationships with obesity, adipose tissue dysfunction and glucose variability]

AIM

Ghrelin, a peptide hormone mostly produced by stomach, plays an important role in regulation of feeding behavior, energy balance and glucose homeostasis.

THE AIM

to determine the relationships between fasting serum levels of ghrelin, body composition, adipose tissue endocrine function and glucose variability (GV) in type 2 diabetic subjects with and without obesity.

MATERIALS AND METHODS

We observed 124 individuals with type 2 diabetes, including 42 non - obese subjects and 82 patients with obesity. Thirty non - obese healthy subjects were acted as control. The concentrations of ghrelin, leptin, resistin, and visfatin in the fasting serum were determined by Multiplex analysis. Body composition was assessed with DEXA. The 24-hour and nocturnal GV parameters were derived from continuous glucose monitoring.

RESULTS AND DISCUSSION

Ghrelin levels in patients with diabetes were decreased significantly as compared to control (p.

Targeting Bile Acid-Activated Receptors in Bariatric Surgery

Bariatric surgical procedures, including Roux-en-Y gastric bypass and vertical sleeve gastrectomy, are currently the most effective clinical approaches to achieve a significant and sustainable weight loss. Bariatric surgery also concomitantly improves type 2 diabetes and other metabolic diseases such as nonalcoholic steatohepatitis, cardiovascular diseases, and hyperlipidemia. However, despite the recent exciting progress in the understanding how bariatric surgery works, the underlying molecular mechanisms of bariatric surgery remain largely unknown. Interestingly, bile acids are emerging as potential signaling molecules to mediate the beneficial effects of bariatric surgery. In this review, we summarize the recent findings on bile acids and their activated receptors in mediating the beneficial metabolic effects of bariatric surgery. We also discuss the potential to target bile acid-activated receptors in order to treat obesity and other metabolic diseases.

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.

Evaluation of insulin resistance improvement after laparoscopic sleeve gastrectomy or gastric bypass surgery with HOMA-IR

Our purpose was to explore the remission of insulin resistance after bariatric surgery to discover the mechanism of diabetes remission excluding dietary factors. A retrospective case control study was conducted on patients with type 2 diabetes, who underwent laparoscopic sleeve gastrectomy (LSG) or laparoscopic gastric bypass surgery (LGB) in Beijing Shijitan Hospital from April 1, 2012 to April 1, 2013. The laboratory and anthropometric data was analyzed pre-surgery and during a 2-year follow-up. HOMA-IR was calculated and evaluated. The two surgical procedures were compared. No significant difference in complete remission rate was observed between the two groups (LGB group: 62.1%, LSG group: 60.0%, p = 0.892). HOMA-IR was reduced to a stable level at the 3^rd month after surgery. The cut-off value of HOMA-IR was 2.38 (sensitivity: 0.938, specificity: 0.75) and 2.33 (sensitivity: 0.941, specificity: 0.778) respectively for complete remission after LSG or LGB surgery. Insulin resistance was improved while GLP-1 and Ghrelin was changed significantly in patients with type 2 diabetes prior to weight loss either in the LSG or LGB group. HOMA-IR decreased to less than the cut-off value at the 3^rd month and was closely related to complete remission. The mechanism of bariatric surgery was not due just to simply dietary factors or body weight loss but also the remission of insulin resistance.