The effect of vertical sleeve gastrectomy on food choice in rats.
ABSTRACT: Diets high in fat are implicated in the development and maintenance of obesity, and obese individuals display greater preferences for high-fat foods than do their lean counterparts. Weight-reduction bariatric surgery is associated with changes in food choice. In particular, after Roux-en-Y gastric bypass (RYGB), humans and rodents select or prefer foods that are lower in fat content. We asked whether a bariatric surgical procedure limited to the stomach, vertical sleeve gastrectomy (VSG), causes a similar reduction of fat intake/preference.Rats received VSG or Sham surgery or remained surgically naïve, and were assessed for food preference using three diet-choice paradigms. Using progressive-ratio (PR) and conditioned taste aversion paradigms, we further asked whether surgically induced changes in food choice are secondary to changes in the reward value of food and/or to the formation of a food aversion. Finally, food choice was compared between VSG- and RYGB-operated rats.VSG rats decreased their intake of dietary fat, and shifted their preference toward lower caloric-density foods. This change in food choice was not associated with changes in motivated responding on a PR schedule for either a fat or a carbohydrate food reinforcer. When VSG and RYGB were compared directly, both procedures caused comparable changes in food choice. The conditioned taste aversion paradigm revealed that VSG rats form an aversion to an intra-gastric oil administration whereas RYGB rats do not.VSG and RYGB, two anatomically distinct bariatric procedures, produce similar changes in food choice.
Project description:BACKGROUNDBariatric surgeries are the most effective treatments for successful and sustained weight loss, but individuals vary in treatment response. Understanding the neurobiological and behavioral mechanisms accounting for this variation could lead to the development of personalized therapeutic approaches and improve treatment outcomes. The primary objectives of this study were to investigate changes in taste preferences and taste-induced brain responses after Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) and to identify potential taste-related predictors of weight loss.METHODSFemales, ages 18 to 55, with a body mass index greater than or equal to 35 kg/m2, and approved for bariatric surgery at the Johns Hopkins Center for Bariatric Surgery were recruited for participation. Demographics, anthropometrics, liking ratings, and neural responses to varying concentrations of sucrose plus fat mixtures were assessed before and after surgery via visual analog scales and functional MRI.RESULTSBariatric surgery produced decreases in liking for sucrose-sweetened mixtures. Greater preference for sucrose-sweetened mixtures before surgery was associated with greater weight loss in RYGB, but not VSG. In the RYGB group only, individuals who showed lower taste-induced activation in the ventral tegmental area (VTA) before surgery and greater changes in taste-induced VTA activation 2 weeks following surgery experienced increased weight loss.CONCLUSIONThe anatomical and/or metabolic changes associated with RYGB may more effectively "reset" the neural processing of reward stimuli, thereby rescuing the blunted activation in the mesolimbic pathway found in patients with obesity. Further, these findings suggest that RYGB may be particularly effective in patients with a preference for sweet foods.FUNDINGNIH K23DK100559 and Dalio Philanthropies.
Project description:It is well established that bariatric surgery, the most effective method to achieve long-term weight loss in obese subjects, reverses enhanced preference and intake of sweet/fatty foods. Although taste and odor preference changes following bariatric surgery have been previously described, their time course and relationship to weight loss remains an issue. The aim of this study was to determine the relationship between taste and odor preference changes and successful weight loss following bariatric surgery. A cross-sectional study was performed on 195 human subjects with body mass index (BMI) above 30 (at least class I obesity), who were scheduled to receive (n = 54) or had previously received (n = 141) Roux-en-Y gastric bypass (RYGB). A Self-Assessment Manikin test was used to measure each participant's affective reaction (ranging from pleasure to displeasure) to a variety of food-related and odor-related pictures. Results confirmed earlier reports about changes in sweet/fatty foods preference after surgery and revealed a shift in preference toward less calorie-dense foods. Relatedly, endorsements of "favorite" foods were mostly sweet/fatty foods in subjects awaiting surgery but were shifted toward more healthy choices, particularly vegetables, in subjects post-RYGB surgery. However, food preference ratings trended toward pre-surgical levels as the time since surgery increased. Answers to open-ended questions about why their diet changed post-surgery revealed that changes in cravings, rather than changes in taste per se, were the major factor. Surprisingly, patients rating a coffee taste as more pleasing after surgery had a lower post-surgical BMI. No associations of odors with change in BMI were apparent. Results showed that following bariatric surgery taste preferences are significantly altered and that these changes correlate with lowered BMI. However, these changes fade as time since surgery lengthens. These results may suggest diagnostic criteria to identify people at risk for less than optimal changes in BMI following bariatric surgery.
Project description:This prospective, observational fMRI study examined changes over time in blood oxygen level dependent (BOLD) response to high- and low-calorie foods (HCF and LCF) in bariatric surgery candidates and weight-stable controls.Twenty-two Roux-en-Y gastric bypass (RYGB) participants, 18 vertical sleeve gastrectomy (VSG) participants, and 19 weight-stable controls with severe obesity underwent fMRI before and 6 months after surgery/baseline. BOLD signal change in response to images of HCF vs. LCF was examined in a priori regions of interest.RYGB and VSG participants lost 23.6% and 21.1% of initial weight, respectively, at 6 months, and controls gained 1.0%. Liking ratings for HCF decreased significantly in the RYGB and VSG groups but remained stable in the control group. BOLD response in the ventral tegmental area (VTA) to HCF (vs. LCF) declined significantly more at 6 months in RYGB compared to control participants but not in VSG participants. Changes in fasting ghrelin correlated positively with changes in VTA BOLD signal in both RYGB and VSG but not in control participants.Results implicate the VTA as a critical site for modulating postsurgical changes in liking of highly palatable foods and suggest ghrelin as a potential substrate requiring further investigation.
Project description:BACKGROUND AND PURPOSE:Roux-en-Y gastric bypass surgery (RYGB) remains one of the most effective treatments for obesity and type 2 diabetes. Despite this, the mechanisms through which it acts are still not well understood. Bile acid signaling through the transmembrane G-protein-coupled receptor TGR5 has been shown to have significant effects on metabolism and has recently been reported to be necessary for the full effects of vertical sleeve gastrectomy (VSG), a bariatric surgery with similar effects to RYGB. The goal of the current study is therefore to investigate the role of bile acid signaling through TGR5 to see if it is necessary to obtain the full effects of RYGB. METHODS:High-fat diet-induced obese TGR5-/- and wildtype mice (WT) were subjected to RYGB, sham surgery, or weight matching (WM) to RYGB mice via caloric restriction. Body weight, body composition, food intake, energy expenditure, glucose tolerance, insulin sensitivity, and liver weight were measured. RESULTS:Although the difference in fat mass 20 weeks after surgery between RYGB and sham-operated mice was slightly reduced in TGR5-/- mice when compared to wildtype mice, loss of body weight and fat mass from preoperative levels, reduction of food intake, increase of energy expenditure, and improvement in glycemic control were similar in the two genotypes. Furthermore, improvements in glycemic control were similar in non-surgical mice weight-matched to RYGB. CONCLUSIONS:We conclude that bile acid signaling through TGR5 is not required for the beneficial effects of RYGB in the mouse and that RYGB and VSG may achieve their similar beneficial effects through different mechanisms.
Project description:Importance:There are few nationwide studies comparing the risk of reintervention after contemporary bariatric procedures. Objective:To compare the risk of intervention after Roux-en-Y gastric bypass (RYGB) vs vertical sleeve gastrectomy (VSG). Design, Setting, and Participants:This cohort study used a nationwide US commercial insurance claims database. Adults aged 18 to 64 years who underwent a first RYGB or VSG procedure between January 1, 2010, and June 30, 2017, were matched on US region, year of surgery, most recent presurgery body mass index (BMI) category (based on diagnosis codes), and baseline type 2 diabetes. The prematch pool included 4496 patients undergoing RYGB and 8627 patients undergoing VSG, and the final weighted matched sample included 4476 patients undergoing RYGB and 8551 patients undergoing VSG. Exposures:Bariatric surgery procedure type (RYGB vs VSG). Main Outcomes and Measures:The primary outcome was any abdominal operative intervention after the index procedure. Secondary outcomes included the following subtypes of operative intervention: biliary procedures, abdominal wall hernia repair, bariatric conversion or revision, and other abdominal operations. Nonoperative outcomes included endoscopy and enteral access. Time to first event was compared using multivariable Cox proportional hazards regression modeling. Results:Among 13?027 patients, the mean (SD) age was 44.4 (10.3) years, and 74.1% were female; 13.7% had a preoperative BMI between 30 and 39.9, 45.8% had a preoperative BMI between 40 and 49.9, and 24.2% had a preoperative BMI of at least 50. Patients were followed up for up to 4 years after surgery (median, 1.6 years; interquartile range, 0.7-3.2 years), with 41.9% having at least 2 years of follow-up and 16.3% having at least 4 years of follow-up. Patients undergoing VSG were less likely to have any subsequent operative intervention than matched patients undergoing RYGB (adjusted hazard ratio [aHR], 0.80; 95% CI, 0.72-0.89) and similarly were less likely to undergo biliary procedures (aHR, 0.77; 95% CI, 0.67-0.90), abdominal wall hernia repair (aHR, 0.60; 95% CI, 0.47-0.75), other abdominal operations (aHR, 0.71; 95% CI, 0.61-0.82), and endoscopy (aHR, 0.54; 95% CI, 0.49-0.59) or have enteral access placed (aHR, 0.58; 95% CI, 0.39-0.86). Patients undergoing VSG were more likely to undergo bariatric conversion or revision (aHR, 1.83; 95% CI, 1.19-2.80). Conclusions and Relevance:In this nationwide study, patients undergoing VSG appeared to be less likely than matched patients undergoing RYGB to experience subsequent abdominal operative interventions, except for bariatric conversion or revision procedures. Patients considering bariatric surgery should be aware of the increased risk of subsequent procedures associated with RYGB vs VSG as part of shared decision-making around procedure choice.
Project description:The effect of vertical sleeve gastrectomy (VSG) on food preference has not been examined in humans, but VSG decreases preference for fat and calorically dense foods in rodents. A validated Food Preference Questionnaire (FPQ) assessed food preference changes before and 6 weeks after VSG in humans. The FPQ was completed before and 43?±?19 days (Mean?±?SD) after VSG. Fifteen subjects (14 females) completed the study. Hedonic ratings decreased for foods high in fat and sugar (p?=?0.002) and high in fat and complex carbohydrate (p?=?0.007). Fat preference (p?=?0.048) decreased, VSG reduced preference for calorically dense foods high in fat, sugar, and complex carbohydrate, and these changes may contribute to the weight loss with VSG.
Project description:OBJECTIVE:We investigated whether vertical sleeve gastrectomy (VSG) and Roux-en-Y gastric bypass surgery (RYGB) have a differential impact on post-operative risk of acute pancreatitis (AP). METHODS:This retrospective study uses the 2012-2014 National Readmission Database. We compared morbidly obese patients who underwent VSG (n?=?205,251), RYGB (n?=?169,973), and hernia repair (HR) control (n?=?16,845). Our main outcome was rates of AP within 6 months post- vs. 6 months pre-surgery in VSG, RYGB, and HR. We also investigated risk factors and outcomes of AP after bariatric surgery. RESULTS:The rates of AP increased post- vs. pre-VSG (0.21% vs. 0.04%; adjusted odds ratio [aOR]?=?5.16, P?<?0.05) and RYGB (0.17% vs. 0.07%; aOR?=?2.26, P?<?0.05) but not post-HR. VSG was associated with a significantly greater increase in AP risk compared to RYGB (aOR?=?2.28; 95% CI: 1.10, 4.73). Furthermore, when compared to HR controls, only VSG was associated with a higher AP risk (aOR?=?7.58; 95% CI: 2.09, 27.58). Developing AP within 6 months following bariatric surgery was mainly associated with younger age (18-29 years old: aOR?=?3.76 for VSG and aOR: 6.40 for RYGB, P?<?0.05) and gallstones (aOR?=?85.1 for VSG and aOR?=?46 for RYGB, P?<?0.05). No patients developed "severe AP" following bariatric surgery. CONCLUSIONS:More patients develop AP within 6 months after VSG compared to RYGB and controls. This risk is highest for younger patients and those with gallstones. Prospective studies examining mechanisms and prevention are warranted.
Project description:BACKGROUND:Roux-en-Y gastric bypass (RYGB) surgery is a very effective bariatric procedure to achieve significant and sustained weight loss, yet little is known about the procedure's impact on the brain. This study examined the effects of RYGB on the brain's response to the anticipation of highly palatable versus regular food. METHODS:High fat diet-induced obese rats underwent RYGB or sham operation and were then tested for conditioned place preference (CPP) for the bacon-paired chamber, relative to the chow-paired chamber. After CPP, animals were placed in either chamber without the food stimulus, and brain-glucose metabolism (BGluM) was measured using positron emission tomography (?PET). RESULTS:Bacon CPP was only observed in RYGB rats that had stable weight loss following surgery. BGluM assessment revealed that RYGB selectively activated regions of the right and midline cerebellum (Lob 8) involved in subjective processes related to reward or expectation. Also, bacon anticipation led to significant activation in the medial parabrachial nuclei (important in gustatory processing) and dorsomedial tegmental area (key to reward, motivation, cognition and addiction) in RYGB rats; and activation in the retrosplenial cortex (default mode network), and the primary visual cortex in control rats. CONCLUSIONS:RYGB alters brain activity in areas involved in reward expectation and sensory (taste) processing when anticipating a palatable fatty food. Thus, RYGB may lead to changes in brain activity in regions that process reward and taste-related behaviors. Specific cerebellar regions with altered metabolism following RYGB may help identify novel therapeutic targets for treatment of obesity.
Project description:BACKGROUND:Weight regain and type-2 diabetes relapse has been reported in a significant proportion of vertical sleeve gastrectomy (VSG) patients in some studies, but definitive conclusions regarding the long-term comparative effectiveness of VSG and Roux-en-Y gastric bypass (RYGB) surgery are lacking both in humans and rodent models. This study's objective was to compare the effects of murine models of VSG and RYGB surgery on body weight, body composition, food intake, energy expenditure, and glycemic control. METHODS:VSG, RYGB, and sham surgery was performed in high-fat diet-induced obese mice, and the effects on body weight and glycemic control were observed for a period of 12 weeks. RESULTS:After the initial weight loss, VSG mice regained significant amounts of body weight and fat mass that were only marginally lower than in sham-operated mice. In contrast, RYGB produced sustained loss of body weight and fat mass up to 12 weeks and drastically improved fasting insulin and HOMA-IR compared with sham-operated mice. Using weight-matched control groups, we also found that the adaptive hypometabolic response to weight loss was blunted by both VSG and RYGB, and that despite large weight/fat regain, fasting insulin and HOMA-IR were markedly improved, but not reversed, in VSG mice. CONCLUSIONS:VSG is less effective to lastingly suppress body weight and improve glycemic control compared with RYGB in mice. Given similar observations in many human studies, the run towards replacing RYGB with VSG is premature and should await carefully controlled randomized long-term trials with VSG and RYGB.
Project description:OBJECTIVE:Roux-en-Y gastric bypass surgery and vertical sleeve gastrectomy (VSG) are the most commonly performed bariatric procedures. Whereas studies report new-onset alcohol misuse following Roux-en-Y gastric bypass, the impact of VSG on alcohol intake is less clear. Hedonic feeding, alcohol drinking, and hypothalamic obesity-related gene expression following VSG were evaluated. METHODS:Male Long-Evans rats underwent VSG or sham surgery. To evaluate hedonic feeding, rats received a high-fat diet following behavioral satiation on chow. Alcohol (5%-10% v/v) drinking was assessed in a two-bottle choice paradigm. Finally, polymerase chain reaction array evaluated gene expression. RESULTS:VSG induced moderate but significant weight loss. Sham rats significantly escalated high-fat diet intake following behavioral satiation, an effect significantly reduced in VSG rats. A moderate decrease in alcohol intake was observed in VSG rats at low (5%) alcohol concentration. However, overall, no significant between-group differences were evident. Key hypothalamic orexigenic transcripts linked to stimulation of food and alcohol intake were significantly decreased in VSG rats. CONCLUSIONS:VSG attenuated hedonic feeding without impacting alcohol drinking, an effect potentially mediated by alterations in genetic information flow within the hypothalamus. Importantly, these data highlight VSG as an effective bariatric procedure with a potentially reduced risk of developing alcohol use disorder.