A nutrient drink test to assess maximum tolerated volume and postprandial symptoms: effects of gender, body mass index and age in health

The melanocortin-4 receptor pathway and the emergence of precision medicine in obesity management

Over the past few decades, there has been a global surge in the prevalence of obesity, rendering it a globally recognized epidemic. Contrary to simply being a medical condition, obesity is an intricate disease with a multifactorial aetiology. Understanding the precise cause of obesity remains a challenge; nevertheless, there seems to be a complex interplay among biological, psychosocial and behavioural factors. Studies on the genetic factors of obesity have revealed several pathways in the brain that play a crucial role in food intake regulation. The best characterized pathway, thus far, is the leptin-melanocortin pathway, from which disruptions are responsible for the majority of monogenic obesity disorders. The effectiveness of conservative lifestyle interventions in addressing monogenic obesity has been limited. Therefore, it is crucial to complement the management strategy with pharmacological and surgical options. Emphasis has been placed on developing drugs aimed at replacing the absent signals, with the goal of restoring the pathway. In both monogenic and polygenic forms of obesity, outcomes differ across various interventions, likely due to the multifaceted nature of the disease. This underscores the need to explore alternative therapeutic strategies that can mitigate this heterogeneity. Precision medicine can be regarded as a powerful tool that can address this concern, as it values the understanding of the underlying abnormality triggering the disease and provides a tailored treatment accordingly. This would assist in optimizing outcomes of the current therapeutic approaches and even aid in the development of novel treatments capable of more effectively managing the global obesity epidemic.

The role of gastric function in control of food intake (and body weight) in relation to obesity, as well as pharmacological and surgical interventions

PURPOSE

The objectives of this review are to summarize the role of gastric motor functions in the development of satiation (defined broadly as postprandial fullness) and satiety (reduced appetite or postponing desire to eat after a meal) and their impact on weight change. The specific topics are the methods of measurement of gastric emptying and accommodation and their impact on food intake, satiation, and satiety. A second focus contrasts bariatric surgery to endoscopic gastroplasty that alter gastric emptying and incretin responses in markedly divergent manners.

BACKGROUND

The hormone, GLP-1, retards gastric emptying and increases gastric accommodation through vagally-mediated effects. Indeed, these effects provide the basis for the association of altered gastric emptying in the appetite and weight loss responses to pharmacological interventions particularly by those acting on receptors of incretin agonists such as liraglutide and the dual agonists, tirzepatide and cotadutide, all of which retard gastric emptying. In fact, retardation of gastric emptying and gastrointestinal adverse effects have been shown to contribute in part to the weight loss in response to this class of pharmacological agents.

SUMMARY

The motor functions of the stomach are relevant to postprandial fullness and to interventions aimed at weight loss in people with obesity.

Neurohormonal response patterns to hunger, satiation, and postprandial fullness in normal weight, anorexia nervosa, and obesity

BACKGROUND

Food intake is regulated by homeostatic and hedonic systems that interact in a complex neuro-hormonal network. Dysregulation in energy intake can lead to obesity (OB) or anorexia nervosa (AN). However, little is known about the neurohormonal response patterns to food intake in normal weight (NW), OB, and AN.

MATERIAL & METHODS

During an ad libitum nutrient drink (Ensure®) test (NDT), participants underwent three pseudo-continuous arterial spin labeling (pCASL) MRI scans. The first scan was performed before starting the NDT after a > 12 h overnight fast (Hunger), the second after reaching maximal fullness (Satiation), and the third 30-min after satiation (postprandial fullness). We measured blood levels of ghrelin, cholecystokinin (CCK), glucagon-like peptide (GLP-1), and peptide YY (PYY) with every pCASL-MRI scan. Semiquantitative cerebral blood flow (CBF) maps in mL/100 gr brain/min were calculated and normalized (nCBF) with the CBF in the frontoparietal white matter. The hypothalamus (HT), nucleus accumbens [NAc] and dorsal striatum [DS] were selected as regions of interest (ROIs).

RESULTS

A total of 53 participants, 7 with AN, 17 with NW (body-mass index [BMI] 18.5-24.9 kg/m2 ), and 29 with OB (BMI ≥30 kg/m2 ) completed the study. The NW group had a progressive decrease in all five ROIs during the three stages of food intake (hunger, satiation, and post-prandial fullness). In contrast, participants with OB showed a minimal change from hunger to postprandial fullness in all five ROIs. The AN group had a sustained nCBF in the HT and DS, from hunger to satiation, with a subsequent decrease in nCBF from satiation to postprandial fullness. All three groups had similar hormonal response patterns with a decrease in ghrelin, an increase in GLP-1 and PYY, and no change in CCK.

CONCLUSION

Conditions of regulated (NW) and dysregulated (OB and AN) energy intake are associated with distinctive neurohormonal activity patterns in response to hunger, satiation, and postprandial fullness.

A Randomized, Controlled Trial of Efficacy and Safety of Cannabidiol in Idiopathic and Diabetic Gastroparesis

BACKGROUND & AIMS

Cannabis (delta-9-tetrahydrocannabinol), a nonselective cannabinoid-receptor agonist, relieves nausea and pain. Cannabidiol (CBD), a cannabinoid receptor 2 inverse agonist with central effects, also reduces gut sensation and inflammation. We compared the effects of 4 weeks of treatment with pharmaceutical CBD vs placebo in patients with idiopathic or diabetic (diabetes mellitus) gastroparesis.

METHODS

We performed a randomized, double-blinded, placebo-controlled study of CBD twice daily (Epidiolex escalated to 20 mg/kg/d; Jazz Pharmaceuticals, Dublin, Ireland) in patients with nonsurgical gastroparesis with delayed gastric emptying of solids (GES). Symptoms were assessed by the Gastroparesis Cardinal Symptom Index Daily Diary. After 4 weeks of treatment, we measured GES, gastric volumes, and Ensure (Abbott Laboratories, Abbott Park, IL) satiation test (1 kcal/mL, 30 mL/min) to assess volume to comfortable fullness and maximum tolerance. Patients underwent specific FAAH and CNR1 genotyping. Statistical analysis compared 2 treatments using analysis of variance including baseline measurements and body mass index as covariates.

RESULTS

Among 44 patients (32 idiopathic, 6 diabetes mellitus type 1, and 6 diabetes mellitus type 2), 5 patients did not tolerate full-dose escalation; 3 withdrew before completing 4 weeks of treatment (2 placebo, 1 CBD); 95% completed 4 weeks of treatment and diaries. Compared with placebo, CBD reduced the total Gastroparesis Cardinal Symptom Index score (P = .008), inability to finish a normal-sized meal (P = .029), number of vomiting episodes/24 hours (P = .006), and overall symptom severity (P = .034). Patients treated with CBD had a higher volume to comfortable fullness and maximum tolerance and slower GES. FAAH rs34420 genotype significantly impacted nutrient drink ingestion. The most common adverse events reported were diarrhea (14 patients), fatigue (8 patients), headache (8 patients), and nausea (7 patients).

CONCLUSIONS

CBD provides symptom relief in patients with gastroparesis and improves the tolerance of liquid nutrient intake, despite slowing of GES.

CLINICALTRIALS

gov NCT #03941288.

The New Zealand eating behavior questionnaire - Validation study for a novel assessment tool to describe actionable eating behavior traits

Individualised management of obesity remains challenging and, to date, most treatment is based on clinical judgement. This study aimed to develop and validate a novel questionnaire-based tool to identify three pre-defined eating behavior (EB) traits, emotional eating, reduced satiety (constant hunger) and reduced satiation (feasters) that may predict selective medication response given their targeted actions. We recruited 977 individuals from a tertiary academic diabetes clinic to participate in this two-phase validation study. Participants self-reported weight management activities and were asked to self-assess their EB characteristics. The initial questionnaire included 42 visual analogue scale questions. In Phase I, 729 participants completed the questionnaire, including Māori (11.8%) and Pacific peoples (19.3%). After random division of the study sample, Exploratory Factor Analysis (EFA) confirmed a three-factor model as the best fit. Stepwise removal of items with inadequate factor loading retained 27 of 42 items, which accounted for 96% of the variance. Confirmatory Factor Analysis (CFA), performed on the second half of the sample, demonstrated good model fit with the final 27-item questionnaire. Internal consistency was high for factor (α = 0.82-0.95) and demographic subgroups, and similar to those obtained in the EFA. Test-retest reliability in a subset of 399 participants who repeated the questionnaire after a four-week interval (Phase II) showed moderate to good reliability. Participants classified into one of three EB types based on the highest median score among the factors. Test-retest reliability was robust for emotional eaters (71.25%) and constant hunger (68.9%). The correlation between aggregate EB score (sum of three EB scores) and BMI was significant (Spearman rho = 0.314, P = .0005). The questionnaire reliably identified three distinct EB traits, which may be informative for precision medicine applications for obesity management.

Abnormal gastrointestinal motility is a major factor in explaining symptoms and a potential therapeutic target in patients with disorders of gut-brain interaction

The objective of this article is to review the evidence of abnormal gastrointestinal (GI) tract motor functions in the context of disorders of gut-brain interaction (DGBI). These include abnormalities of oesophageal motility, gastric emptying, gastric accommodation, colonic transit, colonic motility, colonic volume and rectal evacuation. For each section regarding GI motor dysfunction, the article describes the preferred methods and the documented motor dysfunctions in DGBI based on those methods. The predominantly non-invasive measurements of gut motility as well as therapeutic interventions directed to abnormalities of motility suggest that such measurements are to be considered in patients with DGBI not responding to first-line approaches to behavioural or empirical dietary or pharmacological treatment.

Factors associated with successful weight loss after liraglutide treatment for obesity

AIM

To identify patient factors, including gastrointestinal functions, that are predictive or associated with weight loss in response to once-daily 3 mg liraglutide administered subcutaneously (SQ) or placebo in obesity.

METHODS

One hundred and thirty-six obese adults (87% female) were randomized in a placebo-controlled, 16-week trial of liraglutide, escalated to 3 mg administered SQ daily. Gastrointestinal functions were measured at baseline and 16 weeks: gastric emptying of solids (GET1/2 ); fasting and postprandial gastric volumes; kcal ingested during ad libitum buffet meal and the nutrient drink test. GET1/2 was also measured at 5 weeks. A multiple variable regression model examined variables associated with weight loss of more than 4 kg at 16 weeks. A parsimonious model using backward selection identified the final model.

RESULTS

Weight loss of more than 4 kg at 16 weeks occurred in 71% of liraglutide- and 16% of placebo-treated patients. In all participants combined, parameters univariately associated with a weight loss of more than 4 kg were GET1/2 at 5 and 16 weeks, weight loss at 5 weeks and kcal intake during the buffet meal at 16 weeks. The final parsimonious model (area under the receiver operator characteristics [AUROC] curve = 0.832) identified that factors associated with more than 4-kg weight loss were GET1/2 at 5 weeks (OR = 2.505; 95% CI: 1.57-3.997) per 50 minutes and kcal intake during ad libitum meal at 16 weeks (OR = 0.721; 95% CI: 0.602-0.864) per 100 kcal. Among only the 60 liraglutide-treated subjects, kcal intake at 16 weeks was associated with 4-kg weight loss (AUROC = 0.757).

CONCLUSIONS

Slower GET1/2 and weight loss at 5 weeks predicted a weight loss of more than 4 kg at 16 weeks in all participants. Among liraglutide-treated adults, weight loss of more than 4 kg was associated with ad libitum meal kcal intake at 16 weeks.

Nutrient Drink Test to Assess Gastric Accommodation in Cyclic Vomiting Syndrome: Single-blinded Parallel Grouped Prospective Study

Background/Aims

Cyclic vomiting syndrome (CVS) is characterized by episodes of nausea and vomiting, separated by symptom-free intervals. The pathogenesis of CVS is poorly understood. Limited data exist on evaluating impaired gastric accommodation as a mechanistic means for symptoms. We aim to determine if CVS patients demonstrate impaired gastric accommodation applying a nutrient drink test (NDT) protocol.

Methods

Through this single-blinded pilot clinical trial, patients with CVS per Rome IV critera and healthy controls were assessed for presence of impaired gastric accommodation by administering an established NDT protocol. Statistical analysis was performed, with data presented as medians and interquartile range.

Results

Eleven CVS patients and 15 healthy controls participated in the study between January 2018 and October 2018. Median age was 42.0 years and 37.0 years; majority of subjects were female, 72.7% and 73.3%, respectively. Demographics were similar between CVS and healthy controls. Almost all healthy controls (93.3%) ingested the complete 500 mL protocol, whereas a smaller proportion (72.7%) were able to complete all 4 doses in the CVS group (P = 0.188). Post-prandial visual analogue scale scores of nausea and abdominal pain were found to be significantly higher in CVS patients compared to healthy controls.

Conclusions

To our knowledge, this is the first NDT protocol in CVS evaluating the role of impaired gastric accommodation and hypersensitivity as a possible pathophysiologic mechanism. Findings from this study suggest the presence of gastric hypersensitivity in a subset of CVS patients. These results provide the foundational data necessary for future larger testing of NDT and diagnostic accuracy in CVS.

Factors Associated With Placebo Treatment Response in Functional Dyspepsia Clinical Trials

INTRODUCTION

Controlling for potential placebo effects is an important aspect of gaining an accurate estimate of how much the therapy alone changes patient symptoms or other end points. When the placebo effect is large, this can lead to only a small fraction of changes seen in the active therapy group being attributed to the therapy itself. This problem has been well studied in some disorders of brain-gut interaction but not in functional dyspepsia where placebo response rates of 40% and higher have been reported. Understanding risk factors for placebo response might lead to changes in trial design that could reduce the magnitude of the problem. This study sought to identify risk factors for the placebo effect in a functional dyspepsia clinical trial with a longer-term aim of suggesting trial design changes that might minimize the problem.

METHODS

A secondary analysis of the clinical trial data was undertaken using 2 arms deemed to involve placebo therapy. Potential predictors were drawn from a wide range of patient characteristics including psychological, clinical, and physiological features.

RESULTS

Predictors of a stronger placebo effect on the gastrointestinal symptom rating scale included higher functional dyspepsia symptom burden at baseline (b = -0.101), coexisting irritable bowel syndrome (b = -0.436), and higher scores on the Nepean Dyspepsia Index eat/drink domain (-0.005). Baseline symptom burden and coexisting irritable bowel syndrome were found to be independent placebo predictors, explaining 13% of the variance in change in gastrointestinal symptom rating scale. Anxiety, childhood sexual abuse, sleep amount, and frequent abdominal pain were also found to be predictors of change in individual symptom scores.

DISCUSSION

The findings of this study yield actionable insights into trial methodology that may help to reduce the magnitude of the placebo effect in future functional dyspepsia treatment trials.

Effects of liraglutide on gastrointestinal functions and weight in obesity: A randomized clinical and pharmacogenomic trial

OBJECTIVE

This study aimed to determine the effects of a long-acting glucagon-like peptide-1 (GLP-1) receptor agonist, liraglutide, and placebo subcutaneously over 16 weeks on weight and gastric functions and to evaluate associations of single-nucleotide polymorphisms in GLP1R (rs6923761) and TCF7L2 (rs7903146) with effects of liraglutide.

METHODS

The study conducted a randomized, parallel-group, placebo-controlled, 16-week trial of liraglutide, escalated to 3 mg subcutaneously daily in 136 otherwise healthy adults with obesity. Weight, gastric emptying of solids (GES), gastric volumes, satiation, and body composition measured at baseline and after treatment were compared in two treatment groups using analysis of covariance.

RESULTS

Liraglutide (n = 59) and placebo (n = 65) groups completed treatment. Relative to placebo, liraglutide increased weight loss at 5 and 16 weeks (both p < 0.05), slowed time to half GES (T_1/2 ) at 5 and 16 weeks (both p < 0.001), and increased fasting gastric volume (p = 0.01) and satiation (p < 0.01) at 16 weeks. GES T_1/2 was positively correlated with weight loss on liraglutide (both p < 0.001). After 16 weeks of liraglutide, GLP1R rs6923761 (AG/AA vs. GG) was associated with reduced percent body fat (p = 0.062), and TCF7L2 rs7903146 (CC vs. CT/TT) was associated with lower body weight (p = 0.015).

CONCLUSIONS

Liraglutide, 3 mg, induces weight loss with delay in GES T_1/2 and reduces calorie intake. Slowing GES and variations in GLP1R and TCF7L2 are associated with liraglutide effects in obesity.

Cannabidiol for Functional Dyspepsia With Normal Gastric Emptying: A Randomized Controlled Trial

INTRODUCTION

Cannabidiol (CBD), a CBR2 agonist with limited psychic effects, antagonizes CB1/CB2 receptors. Allelic variation CNR1 (gene for CBR1) rs806378 and FAAH rs324420 were associated with altered gut motility and sensation. This study aimed to compare the pharmacodynamics and clinical effects of a 4-week treatment with pharmaceutical-grade CBD vs placebo and assess the interactions of FAAH and CNR1 gene variants on the effects of CBD in patients with functional dyspepsia (FD).

METHODS

We performed a randomized, double-blinded, placebo-controlled (1:1 ratio) study of CBD b.i.d. (20 mg/kg/d according to the US Food and Drug Administration escalation guidance) in FD patients with nondelayed gastric emptying (GE) at baseline. Symptoms were assessed by validated daily symptom diary (0-4 scale for upper abdominal pain, nausea, and bloating), weekly assessment of adequate relief, Leuven Postprandial Distress Scale (8 symptoms, adjectival scores rated 0-4 for severity), and quality of life (Short-Form Nepean Dyspepsia Index [average of 10 dimensions each on a 5-point scale]). After the 4-week treatment, all patients underwent measurements of GE of solids, gastric volumes, and Ensure nutrient satiation test. Statistical analysis compared 2 treatments for all endpoints and the effects of CBD in association with FAAH rs324420 and CNR1 rs806378.

RESULTS

CBD and placebo effects on physiological functions and patient response outcomes were not significantly different. There were borderline CBD treatment-by-genotype interactions: rs806378 CNR1 with Leuven Postprandial Distress Scale ( P = 0.06) and GE solids ( P = 0.12).

DISCUSSION

Approved doses of CBD used off-label do not relieve FD with normal baseline GE of solids or alter gastric motor functions and satiation. CBD treatment-by-gene interactions suggest potential benefits for postprandial distress with CNR1 rs806378 T allele.

Clinical trial: a single-centre, randomised, controlled trial of tradipitant on satiation, gastric functions, and serum drug levels in healthy volunteers

BACKGROUND

Tradipitant, an NK1 receptor antagonist, improved symptoms in patients with gastroparesis. It is unclear whether these effects are mediated centrally (e.g., vomiting centre) or on gastric functions. As a class, NK1 antagonists may retard gastric emptying (GE) or increase fasting and postprandial gastric volumes (GV).

AIM

To evaluate the effects of tradipitant relative to placebo on gastric motor functions, satiation, postprandial symptoms, and pharmacokinetics.

METHODS

We conducted a randomised, double-blind, placebo-controlled, single-centre study of tradipitant 85 mg or matching placebo b.i.d. for 9 consecutive days in 24 healthy volunteers. During the last 2 days of treatment, participants underwent scintigraphic measurements of GE of 320 kcal egg meal, fasting and postprandial GV by SPECT, and satiation by nutrient drink ingested to maximum tolerated volume (MTV) and symptoms 30 min later. Treatments were compared by Wilcoxon rank sum test. The study had 80% power to detect group differences of 23.6% in GV and 29.2% in GE T_1/2 .

RESULTS

The two groups of healthy participants were well balanced based on demographic features, age, and BMI. There were nonsignificant positive correlations between blood levels of tradipitant and accommodation GV and GE at 4 h. There were no significant effects of tradipitant, 85 mg b.i.d. for 9 days compared to placebo on GE, GV, satiation, or symptoms 30 min after MTV.

CONCLUSION

Tradipitant, 85 mg b.i.d., does not significantly affect gastric motor functions (GV or GE). Importantly, there was no retardation of GE by tradipitant, which is important in relation to its potential use in patients with gastroparesis.

CLINIC TRIALS REGISTRY

ClinicalTrials.gov #NCT04849559.

Homeostatic regulation of food intake

Food intake and energy expenditure are key regulators of body weight. To regulate food intake, the brain must integrate physiological signals and hedonic cues. The brain plays an essential role in modulating the appropriate responses to the continuous update of the body energy-status by the peripheral signals and the neuronal pathways that generate the gut-brain axis. This regulation encompasses various steps involved in food consumption, include satiation, satiety, and hunger. It is important to have a comprehensive understanding of the mechanisms that regulate food consumption as well as to standardize the vocabulary for the steps involved. This review discusses the current knowledge of the regulation and the contribution peripheral and central signals at each step of the cycle to control appetite. We also highlight how food intake has been measured. The increasingly complex understanding of regulation and action mechanisms intervening in the gut-brain axis offers ambitious targets for new strategies to control appetite.

Precision Medicine and Obesity

Obesity is a chronic, relapsing, and multifactorial disease, with a rising prevalence and an associated high economic burden. Achieving successful and sustained weight loss outcomes with current interventions is challenging. This is due, at least in part, to the disease's heterogenous pathophysiology that is yet to be completely understood. Technological advances and greater capabilities for the extraction and storage of information have facilitated the application of precision medicine. Several precision medicine initiatives have been proposed to improve obesity outcomes. Most of these initiatives are based on -omics technologies. Although the data generated from these technologies have led to developing hypotheses that may explain the underpinnings of obesity, their applicability to the clinical practice is yet to be determined. There are other initiatives that have identified quantitative or qualitative physiologic traits that can be targeted and that could have a more immediate clinical impact. This review aims to provide a perspective of current initiatives for precision medicine for obesity.

Gastric accommodation: Physiology, diagnostic modalities, clinical relevance, and therapies

BACKGROUND

Gastric accommodation is an essential gastric motor function which occurs following ingestion of a meal. Impaired gastric fundic accommodation (IFA) is associated with dyspeptic symptoms. Gastric accommodation is mediated by the vagal pathway with several important physiologic factors such as duodenal nutrient feedback playing a significant role. IFA has been described as a pathophysiologic factor in several gastrointestinal disorders including functional dyspepsia, diabetic gastropathy, post-Nissen fundoplication, postsurgical gastrectomy, and rumination syndrome. Modalities for gastric accommodation assessment include gastric barostat, intragastric meal distribution via scintigraphy, drinking tests (eg, water load), SPECT, MRI, 2D and 3D ultrasound, and intragastric high-resolution manometry. Several treatment options including sumatriptan, buspirone, tandospirone, ondansetron, and acotiamide may improve symptoms by increasing post-meal gastric volume.

PURPOSE

Our aim is to provide an overview of the physiology, diagnostic modalities, and therapies for IFA. A literature search was conducted on PubMed, Google Scholar, and other sources to identify relevant studies available until December 2020. Gastric accommodation is an important gastric motor function which if impaired, is associated with several upper gastrointestinal disorders. There are an increasing number of gastric accommodation testing modalities; however, each has facets which warrant consideration. Evidence regarding potentially effective therapies for IFA is growing.

Randomised clinical trial: safety, pharmacokinetics and pharmacodynamics of trazpiroben (TAK-906), a dopamine D2 /D3 receptor antagonist, in patients with gastroparesis

BACKGROUND

Gastroparesis is a chronic gastric motility disorder. Dopamine D₂ /D₃ receptor antagonists metoclopramide and domperidone are current treatment options but are associated with central nervous system and cardiovascular safety concerns, respectively, precluding chronic use. Trazpiroben (TAK-906), a dopamine D₂ /D₃ receptor antagonist, is under development for chronic treatment of moderate-to-severe gastroparesis. Nonclinical data suggest trazpiroben will have D₂ /D₃ receptor antagonism comparable with metoclopramide or domperidone.

AIMS

To evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics (effect on prolactin and gastric function) of twice-daily trazpiroben (5, 25 and 100 mg) in participants with gastroparesis.

METHODS

This phase 2a pilot study evaluated gastric emptying using the gastric emptying breath test, with metoclopramide as an internal control. Gastric accommodation and gastroparesis symptoms were assessed using the nutrient drink test and American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index-Daily Diary, respectively.

RESULTS

Overall, 51 participants were enrolled. Trazpiroben was well tolerated, demonstrating a favourable safety profile without cardiovascular or central nervous system adverse events. All trazpiroben doses were rapidly absorbed and eliminated (t_1/2z 4-5 hours), and D₂ /D₃ receptor target engagement confirmed by increased serum prolactin (peaking at trazpiroben 25 mg). No effect on gastric emptying was demonstrated with trazpiroben or metoclopramide (P > 0.05), although benefits in volume-to-fullness were seen at trazpiroben 5 mg (P > 0.05) and 25 mg (88.5 vs -26.3 mL; P = 0.019), and nonsignificant numerical aggregate symptom score improvements were observed with trazpiroben 25 mg vs placebo (P = 0.182).

CONCLUSIONS

Trazpiroben was well tolerated with a favourable safety profile, supporting its further development for the treatment of gastroparesis. ClinicalTrials.gov identifier: NCT03268941.

Nutrient Drinking Test as Biomarker in Functional Dyspepsia

INTRODUCTION

Functional dyspepsia (FD) is a prevalent condition with multifactorial pathophysiology, including impaired gastric accommodation (GA), hypersensitivity to gastric distention, and delayed gastric emptying. Drink tests (DT) have been proposed as a potential biomarker for the presence and severity of gastric sensorimotor dysfunction. Thus, we aimed to summarize the state of knowledge on different DT and their potential as a biomarker for FD.

METHODS

A PubMed and MEDLINE search was conducted for English language articles, reviews, meta-analyses, case series, and randomized controlled trials, including also published meeting abstracts.

RESULTS

Several DT have been described in literature (e.g., different type of liquid, number of calories used, pace of drinking, and subject's awareness of the amount of liquid drunk). FD patients ingest significantly less volume in the different variants of the tests. The slow nutrient ("satiety drinking") test (SDT) studies show the most consistent separation between health and FD and correlation with GA. However, sensitivity to distention may be correlated with rapid DT. SDTs were used to evaluate the effect of several pharmacological agents, often showing concordance between their effects on GA and tolerated nutrient volume. This correlation was not found mainly for agents with central actions.

DISCUSSION

An SDT is a potential diagnostic biomarker in FD, reflecting GA. Additional studies are required to confirm its role as a predictive biomarker for treatment outcome in FD.

Personalization of Endoscopic Bariatric and Metabolic Therapies Based on Physiology: a Prospective Feasibility Study with a Single Fluid-Filled Intragastric Balloon

BACKGROUND

The intragastric balloon (IGB) is commonly used for weight loss. Identifying patients who are most likely to tolerate and benefit from IGB therapy will optimize outcomes. Our aims were to prospectively utilize a gastric emptying study to predict intolerance and treatment response with a single fluid-filled IGB and to develop a physiologic prediction model with a treatment algorithm.

MATERIALS AND METHODS

A total of 32 patients had a gastric emptying study before and 2-3 months after placement of an IGB. Multiple logistic regression analyses were performed to calculate likelihood ratios and to develop a physiologic prediction model.

RESULTS

Patients in the higher gastric retention quartile at baseline had a 6.2-time higher likelihood ratio for early balloon removal secondary to intolerance (p = 0.013). Utilizing baseline gastric emptying to predict intolerance to the IGB may have prevented 75% of early removal cases. Decreased gastric emptying at 3 months after balloon placement was significantly correlated with percent total body weight loss (%TWBL) at 6 and 12 months (p = 0.01 and p = 0.014, respectively). At 6 months after IGB, patients with no change in their gastric emptying at 3 months lost significantly less weight compared with those with increased gastric retention (median %TBWL = 9.0% [4.5-14.7] versus 17.3% [12.2-24.4], p = 0.016).

CONCLUSION

Utilizing gastric emptying as a physiologic predictor of intolerance and response to the single fluid-filled IGB can improve outcomes. This pilot feasibility trial ushers in the era of personalized endoscopic bariatric therapies to maximize patients' tolerance, cost-effectiveness, and meaningful weight loss.

Reference values for the water load test in healthy school children and adolescents

BACKGROUND AND STUDY AIM

The water load test (WLT) is an easy and cheap tool, useful in evaluating gastric accommodation and visceral hypersensitivity. This test can be used in diagnosing functional gastrointestinal disorders, like functional dyspepsia. Our main aim was to propose reference values for the WLT. Our secondary aim was to correlate the water volume drunk with the students' gender, age, and anthropometric measures.

PATIENTS AND METHODS

We performed the WLT in students aged 8 to 17 years. Students drank water ad libitum for 3 minutes or until pain, satiety or vomiting occurred. We correlated anthropometric variables with water volumes drunk. Upper and lower limit for the maximum tolerated volume were calculated as the 5th and 95th percentile. Pain and nausea were recorded before and after the test.

RESULTS

We evaluated 99 students, with a median age (inter quartile range) of 11 years 10-13 years) and 55.6 % were girls. Median water volume drank was 380 ml (190-540 ml). Boys (523 ml, interquartile range : 275-760 ml) drank more water than girls (380 ml, interquartile range : 190-570 ml) (p = 0.016). There was a significant correlation between water volume drank and students´ age, weight, height, and body mass index. Of the students that completed the WLT, 22.2 % had nausea and 30.3 % had mild abdominal pain after the test.

CONCLUSIONS

We proposed reference values for the WLT in children aged 8 to 17 years. Adverse effects are minimal, it is safe to perform, and well tolerated.

Gastric Sensory and Motor Functions and Energy Intake in Health and Obesity-Therapeutic Implications

Sensory and motor functions of the stomach, including gastric emptying and accommodation, have significant effects on energy consumption and appetite. Obesity is characterized by energy imbalance; altered gastric functions, such as rapid gastric emptying and large fasting gastric volume in obesity, may result in increased food intake prior to reaching usual fullness and increased appetite. Thus, many different interventions for obesity, including different diets, anti-obesity medications, bariatric endoscopy, and surgery, alter gastric functions and gastrointestinal motility. In this review, we focus on the role of the gastric and intestinal functions in food intake, pathophysiology of obesity, and obesity management.

Functional dyspepsia in children: A study of pathophysiological factors

BACKGROUND AND AIM

Functional dyspepsia (FD) is common in children, and treatment targeted towards the altered pathophysiology can improve outcome. We evaluated FD children for abnormality of gastric accommodation and emptying, psychological stressors (PS), Helicobacter pylori (HP) infection, and post-infectious FD.

METHODS

Diagnosis of FD was based on ROME III criteria. Clinical evaluation including dyspeptic symptom scoring and assessment for PS was performed. Satiety drink test for gastric accommodation, gastroscopy with biopsy for HP infection, and solid meal gastric emptying were performed. Sixty-seven healthy children were enrolled for assessing PS and satiety drink test.

RESULTS

Fifty-five FD children (33 boys, age 12 [6-18] years) with symptoms for 4 (2-48) months and dyspeptic score of 5 (1-13) were enrolled. PS were more common in FD than in controls (46/55 vs 9/67; P < 0.001). Median satiety drink volume was 360 mL (180-1320 mL); no patients had satiety drink volume of < 5th centile of healthy children. The frequency (98% vs 85%; P = 0.01) and severity (65 [10-175] vs 50 [5-130]; P < 0.001) of postprandial symptoms were higher in FD than in controls. Of the postprandial symptoms, pain (20.3% vs 0%; P = 0.000) was present only in FD. Delayed gastric emptying was present in 6.5%, HP infection in 11%, and post-infectious FD in 13% cases. Etiological factor was identified in 87% children, with 20% having multiple factors.

CONCLUSIONS

Abnormality of gastric sensorimotor function is seen in one-fourth of FD cases. HP infection and post-infectious FD are present in 11% and 13% cases, respectively.

Impact of improvement of sleep disturbance on symptoms and quality of life in patients with functional dyspepsia

BACKGROUND/AIMS

Functional dyspepsia (FD) is often comorbid with sleep disturbance. However, it is not fully understood how sleep disturbance affects the pathophysiology of FD. We aimed to investigate the relationship between FD and sleep disturbance.

METHODS

We prospectively enrolled 20 FD patients with sleep disturbance between December 2018 and July 2019. Patients took sleep aids for 4 weeks and filled out questionnaires before and after taking sleep aids. Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and Athens Insomnia Scale (AIS) were used to evaluate the severity of their sleep disturbance. Modified Frequency Scale for the Symptoms of Gastroesophageal Reflux Disease (mFSSG), Gastrointestinal Symptom Rating Scale (GSRS), and the Japanese version of Patient Assessment of Constipation Quality of Life (JPAC-QOL) were used to evaluate the severity of GI symptoms. Short-Form 36-Item Health Survey (SF-36) was used to evaluate QOL. Pre- and post-sleep medication values of questionnaires were compared.

RESULTS

Among 20 enrolled patients, 16 completed the study protocol. Zolpidem, eszopiclone, and suvorexant were administered to six, nine, and one patient, respectively. Each median total score of questionnaires (pre-/post-sleep medication, respectively) was as follows: PSQI, 10.0/8.5; ESS, 12.5/5.0; AIS, 10.0/4.0; mFSSG, 21.0/16.0; GSRS, 44.0/31.0 (Pain in GSRS, 11.0/5.0); JPAC-QOL, 26.0/15.5; SF-36, 63.9/71.9. All of these results showed statistically significant differences between pre- and post-sleep medication (p < 0.05).

CONCLUSIONS

Improvement of sleep disturbance by administration of sleep aids resulted in improvement of GI symptoms and QOL in patients with FD. This effect may be related to pain modification.

Physical activity is associated with accelerated gastric emptying and increased ghrelin in obesity

BACKGROUND

Rapid gastric emptying, increased food intake, and alterations in gastrointestinal hormones are associated with obesity. The effect of regular physical activity (PA) on food intake, gastric emptying (GE), gastric accommodation, and gastrointestinal (GI) hormones in adults with obesity remains unclear. Our aim was to compare, at time of presentation, weight trends, eating behavior, GE, and GI hormone levels among individuals with obesity who engage in regular PA compared to those who do not.

METHODS

In 270 participants with obesity, we performed validated measurements of GI phenotypes: GE of solids and liquids, gastric volume (GV) during fasting and after consumption of 200 mL Ensure®, satiety by kcal intake (T-kcal) during a buffet meal, satiation (volume to fullness [VTF] and maximal tolerated volume [MTV]) of a liquid nutrient, and plasma levels of fasting and postprandial GLP-1, PYY, CCK, and ghrelin. Physical Activity Stages of Change Questionnaire was used to assess whether participants were regularly PA or not.

KEY RESULTS

PA was associated with lower BMI (Δ 2.01 kg/m² , P = .001) and body weight (Δ 4.42 kg, P = .0278). GE of solids (T-50% Δ 7.54 min, P = .021) and liquids (T-50% Δ 2.99 min, P = .029%) was significantly more rapid in physically active participants. PA was also associated with relatively higher postprandial ghrelin AUC (Δ 10.4 pg/mL, P = .015). There was no significant difference in postprandial satiation, satiety, GV, or other GI hormones (CCK, PYY, or GLP-1) between groups.

CONCLUSIONS & INFERENCES

Physical activity is associated with lower BMI, but faster GE and higher postprandial ghrelin levels, two factors that are also associated with obesity.

Associations of gastric volumes, ingestive behavior, calorie and volume intake, and fullness in obesity

Whereas gastric emptying significantly predicts calorie intake, the association between gastric capacity and satiation and satiety is unclear. To study the associations between gastric volumes and ingestive behaviors with satiation and satiety in obesity, 62 healthy adult obese patients (57 female) with no eating disorders underwent measurements of satiety, as determined by kilocalories of ingestion at a buffet meal, and satiation by volume to comfortable fullness (VTF) and maximum tolerated volume (MTV), while drinking Ensure (30 mL/min). Fasting and postprandial gastric volumes were measured by validated single-photon emission computed tomography. We also measured eating [Weight Efficacy Life-Style Questionnaire score (WEL)] and exercise behaviors associated with obesity. Spearman correlation-assessed relationships of measured traits and linear regression analysis to identify predictors of satiation or satiety. The participants were aged 38 ± 10.1 yr and the body mass index (BMI) 36.8 ± 4.8 kg/m². Fasting gastric volume was significantly correlated with VTF (r_s = 0.3, P = 0.03), but not with MTV or buffet meal kilocalorie ingestion. Regression analysis identified sex (P = 0.02, with males having significantly higher fasting gastric volume) and fasting gastric volume (0.04) as predictors of higher VTF. An increase in fasting gastric volume of 50 mL resulted in a 6-mL increase in VTF. Buffet meal intake was inversely related to the ability to resist the urge to eat; factors associated with ingestive behavior (increase in total WEL score) significantly correlated with satiety and gastric accommodation (P < 0.05). Gastric capacity during fasting is associated with calorie intake to the point of comfortable fullness; factors associated with ingestive behavior are associated with satiety and gastric accommodation.NEW & NOTEWORTHY Buffet meal intake was inversely related to the ability to resist the urge to overeat. Factors associated with ingestive behavior significantly correlated with satiety and gastric accommodation. Gastric capacity during fasting is associated with calorie intake to the point of comfortable fullness; factors associated with ingestive behavior are associated with satiety and gastric accommodation.

Functional Dyspepsia: A Narrative Review With a Focus on Sex-Gender Differences

Functional dyspepsia (FD) is among the most common gastrointestinal disorders affecting quality of life (QoL). As it frequently occurs in women than in men the comparison of various aspects including prevalence, clinical manifestations, and QoL in FD between women and men is very important for understanding the disease distribution and burden, evaluating treatment options, developing new drugs, and allocating medical resources. However, little is known about sex or gender differences among patients with FD. In spite of limited studies, consistent points are that FD occurs more often in women than in men and there are several symptom differences between men and women with FD. In addition, women with FD tend to have lower QoL than men with FD. Similarly, the pathophysiology of FD likely to vary depending on gender. Furthermore, a sex-gender-oriented approach in healthcare system could enhance understanding heterogeneous patients suffering from FD. Due to the sex-gender differences in physiological and psychological factors, treatment strategies should differ between women and men with FD. In conclusion, an individualized and multicomponent approach that considers sex and gender issues might improve FD treatment and improve patient Qol, especially for women.

Association between gastrointestinal phenotypes and weight gain in younger adults: a prospective 4-year cohort study

Background/Objectives:

Gastrointestinal phenotypes have previously been associated with obesity, however it is unknown if these phenotypes are a cause or a consequence of obesity and weight gain. Our aim was to assess whether these gastrointestinal phenotypes are associated with future weight gain in younger adults.

Subjects/Methods:

At baseline, 126 adult participants under the age of 35 were weighed and underwent measurement of gastrointestinal phenotypes including gastric emptying (GE), gastric volume, satiation, satiety and gastrointestinal hormones. Patients were re-appraised after median 4.4 years unless, during the period of follow up, they participated in a formal weight loss program, received obesity-weight loss interventions, or developed a health condition likely to affect weight. Participants were dichotomized into two groups for each phenotype at the median of each phenotype.

Results:

In total, 60 participants met criteria for inclusion and were evaluated after a median of 4.4 years [IQR: 3.5 to 5],36 participants were excluded due to conditions that would abnormally affect weight during study period including pregnancy and weight loss treatment, and 30 participants were lost to prospective follow-up. Faster GE was significantly associated with weight gain. Those with faster GE at baseline (n=30) gained a median of 9.6 kg [3.1 to 14.9] compared to those with slower GE at baseline (n=30) who gained a median of 2.8 kg [−4.6 to 9.2] (p=0.03), over the follow-up period. There was no association between the other phenotypes and weight gain.

Conclusions:

In adults ≤35 years old, faster gastric emptying is associated with significantly increased weight gain over the medium term. This provides supportive evidence for the role of gastric emptying in weight gain and development of obesity.

GLP-1 Analog Modulates Appetite, Taste Preference, Gut Hormones, and Regional Body Fat Stores in Adults with Obesity

PURPOSE

Obesity is associated with alterations in appetite, gastrointestinal hormone levels and excessive fat mass. We previously published a double-blind, placebo-controlled, randomized, 16-week trial on effects of once-daily glucagon-like peptide-1 (GLP-1) analog, liraglutide on weight, satiation, and gastric functions in obese volunteers. The aim of this substudy is to compare to placebo the effects of liraglutide on appetite, taste preference, regional body fat stores, and anthropometric measurements.

METHODS

Forty obese adults received standard instruction for weight management, monthly behavioral intervention utilizing motivational interviews, and 16-week treatment of once-daily liraglutide (escalated to 3 mg SQ daily). At baseline and 16 weeks, the following were measured: appetite and taste preferences rated every 30 min for 5 h after ingesting 300 mL Ensure®; maximal tolerated volume (MTV) with a nutrient drink test; fasting and postprandial bioactive GLP-1 (7-36) and peptide YY (PYY) levels; total and regional body fat with dual-energy X-ray absorptiometry, and waist and hip circumference.

RESULTS

Thirty-five participants (17 liraglutide; 18 placebo) completed the trial. Compared to placebo group, liraglutide group had significant reductions in MTV; prospective food consumption score; desire to eat something sweet, salty, savory or fatty; and an increase in perceived fullness. Postprandial plasma levels of GLP-1 decreased and PYY levels increased with liraglutide relative to baseline. Significant reductions in total body, trunk, and upper and lower body fat without reduction in lean body mass were observed.

CONCLUSION

Liraglutide 3 mg SQ modulates appetite, taste preference, gut hormones, and regional body fat stores in adults with obesity without reduction in lean body mass.

Secretin effects on gastric functions, hormones and symptoms in functional dyspepsia and health: randomized crossover trial

Abnormal gastric accommodation (GA) and gastric emptying contribute to pathophysiology in functional dyspepsia (FD). Secretin is a key regulator of GA in animal studies. Our aim was to study the effects of secretin on gastric motility, satiation, postprandial symptoms, and key hormones. We performed two double-blind, randomized, saline-controlled crossover trials in 10 healthy volunteers and 10 patients with FD by Rome IV criteria. We used measured GA (by validated SPECT method) after a ¹¹¹In radiolabeled Ensure 300-mL meal and quantified gastric emptying for 30 min by scintigraphy. Satiation was measured by volume to fullness (VTF) and maximum tolerated volume (MTV) on an Ensure nutrient drink test and postprandial symptoms 30 min post-MTV. Fasting and postprandial GLP-1, GIP, and HPP were measured. The ages and sex distribution of healthy controls and patients with FD were similar. Compared with placebo, secretin delayed gastric emptying at 30 min in both health [-11% (-16, -4), P = 0.004]; and FD [-8% (-9, 0), P = 0.03]. Satiation (VTF and MTV), GA, and plasma levels of GLP-1, GIP, and HPP did not differ between treatment arms in health or FD. On ANCOVA analysis (adjusting for age and sex), secretin did not consistently increase postprandial symptoms in health or FD. Secretin delayed gastric emptying in both health and FD without significantly altering GA, VTF, or MTV or selected hormones. Thus, secretin receptor activation may provide a novel therapeutic mechanism for patients with FD and rapid gastric emptying.NEW & NOTEWORTHY The naturally occurring hormone secretin retards gastric emptying of solids without deleteriously affecting gastric accommodation, satiation, other upper gastrointestinal hormones, or postprandial symptoms. Given these findings, a subset of patients with rapid gastric emptying (e.g., the estimated 20% of patients with functional dyspepsia) could be candidates for treatments that stimulate a secretin receptor such as sacubitril, which inhibits neprilysin, an enzyme that degrades secretin.

Insights on Obesity in Children and Adults: Individualizing Management

For the management of obesity in childhood and adolescence, nonoperative approaches have limited efficacy, including community-based and behavioral interventions and pharmacotherapy approved for use in adults. Roux-en-Y gastric bypass (RYGB) and laparoscopic sleeve gastrectomy are efficacious in reducing weight, body mass index, and comorbidities in adolescents. Understanding the phenotype associated with obesity provides an opportunity to individualize patients' treatments directed at the brain-gut axis. These phenotypes include rapid gastric emptying, increased fasting gastric volume, reduced postprandial incretins, and central mechanisms that impact appetite and satiation including hedonic eating and affective disorders. Further studies are required in adolescents. Identifying phenotypes could enhance the efficacy of behavioral, dietary, and pharmacotherapeutic interventions alone or in combination in children and adolescents.

Biological Response to Meal Ingestion: Gender Differences

In a previous study, we demonstrated that women enjoyed and tolerated lower meal loads than men. Hence, we hypothesized that with the same meal load, their postprandial response is more pronounced than in men. We performed a randomized parallel trial in 12 women and 12 men comparing the postprandial responses to a palatable comfort meal. We measured homeostatic sensations (hunger/satiety, fullness) and hedonic sensations (digestive well-being, mood) on 10 cm scales, vagal tone by heart ratio variability and the metabolomic profile before and after meal ingestion. Gender differences were analyzed by repeated measures ANCOVA. Overall (n = 24), ingestion of the probe meal induced satiation, fullness, digestive well-being and improved mood (main time-effect p ≤ 0.005 for all). Women exhibited a more intense sensory experience, specially more postprandial fullness, than men [main gender-effect F (1, 21) = 7.14; p = 0.014]; hedonic responses in women also tended to be stronger than in men. Women exhibited more pronounced effects on vagal tone [main gender-effect F (1, 21) = 5.5; p = 0.029] and a different lipoprotein response than men. In conclusion, our data indicate that gender influences the responses to meal ingestion, and these differences may explain the predisposition and higher incidence in women of meal-related functional disorders.

GI Motility Testing: Stomach, Small Bowel, and Colon

Symptoms of abdominal pain, nausea, vomiting, bloating, abdominal distention, diarrhea, and constipation are common and may relate to abnormalities in gastrointestinal motility. There are a number of different options to study gastrointestinal motility. This article reviews novel and standard motility tests available in the stomach, small bowel, and colon. The indications for testing, technical details, advantages, and disadvantages of each test will be summarized.

Meal Enjoyment and Tolerance in Women and Men

Various conditioning factors influence the sensory response to a meal (inducible factors). We hypothesized that inherent characteristics of the eater (constitutive factors) also play a role. The aim of this proof-of-concept study was to determine the role of gender, as an individual constitutive factor, on the meal-related experience. Randomized parallel trial in 10 women and 10 men, comparing the sensations before, during, and after stepwise ingestion of a comfort meal up to full satiation. Comparisons were performed by repeated Analysis of Covariance (ANCOVA) measures. During stepwise ingestion, satisfaction initially increased up to a peak, and later decreased down to a nadir at the point of full satiation. Interestingly, the amount of food consumed at the well-being peak was lower, and induced significantly less fullness in women than in men. Hence, men required a larger meal load and stronger homeostatic sensations to achieve satisfaction. The same pattern was observed at the level of full satiation: men ate more and still experienced positive well-being, whereas in women, well-being scores dropped below pre-meal level. The effect of gender on the ingestion experience suggests that other constitutive factors of the eater may also influence responses to meals.

Electroacupuncture plus standard of care for managing refractory functional dyspepsia: protocol of a pragmatic trial with economic evaluation

INTRODUCTION

This trial proposes to compare the effectiveness and cost-effectiveness of electroacupuncture (EA) plus on-demand gastrocaine with waiting list for EA plus on-demand gastrocaine in providing symptom relief and quality-of-life improvement among patients with functional dyspepsia (FD).

METHODS AND ANALYSIS

This is a single-centre, pragmatic, randomised parallel-group, superiority trial comparing the outcomes of (1) EA plus on-demand gastrocaine group and (2) waiting list to EA plus on-demand gastrocaine group. 132 (66/arm) endoscopically confirmed, Helicobacter pylori-negative patients with FD will be recruited. Enrolled patients will respectively be receiving (1) 20 sessions of EA over 10 weeks plus on-demand gastrocaine; or (2) on-demand gastrocaine and being nominated on to a waiting list for EA, which entitles them 20 sessions of EA over 10 weeks after 12 weeks of waiting. The primary outcome will be the between-group difference in proportion of patients achieving adequate relief of symptoms over 12 weeks. The secondary outcomes will include patient-reported change in global symptoms and individual symptoms, Nepean Dyspepsia Index, Nutrient Drink Test, 9-item Patient Health Questionnaire (PHQ9), and 7-item Generalised Anxiety Disorder Scale (GAD7). Adverse events will be assessed formally. Results on direct medical costs and on the EuroQol (EQ-5D) questionnaire will also be used to assess cost-effectiveness. Analysis will follow the intention-to-treat principle using appropriate univariate and multivariate methods. A mixed model analysis taking into account missing data of these outcomes will be performed. Cost-effectiveness analysis will be performed using established approach.

ETHICS AND DISSEMINATION

The study is supported by the Health and Medical Research Fund, Government of the Hong Kong Special Administrative Region of China. It has been approved by the Joint Chinese University of Hong Kong - New Territories East Cluster Clinical Research Ethics Committee. Results will be published in peer-reviewed journals and be disseminated in international conference.

TRIAL REGISTRATION NUMBER

ChiCTR-IPC-15007109; Pre-result.

Effects of Antidepressants on Gastric Function in Patients with Functional Dyspepsia

BACKGROUND

Functional dyspepsia (FD) is a highly prevalent functional bowel disorder. The effects of antidepressant therapy (ADTx) on gastric sensorimotor function in FD patients are poorly understood.

AIMS

Determine whether FD and subtypes with abnormalities in gastric function respond differently to ADTx compared to those with normal physiology.

METHODS

This multicenter, prospective trial randomized FD patients to 12 weeks of amitriptyline (AMI; 50 mg), escitalopram (ESC; 10 mg), or matching placebo. Demographics, symptoms, psychological distress, gastric emptying, and satiation were measured. Gastric accommodation (GA) using single-photon emission computed tomography imaging was performed in a subset of patients. An intent to treat analysis included all randomized subjects. The effect of treatment on gastric emptying was assessed using ANCOVA. A post hoc appraisal of the data was performed categorizing patients according to the Rome III subgrouping (PDS and EPS).

RESULTS

In total, 292 subjects were randomized; mean age=44 yrs. 21% had delayed gastric emptying. Neither antidepressant altered gastric emptying, even in those with baseline delayed gastric emptying. GA increased with ADTx (P=0.02). Neither antidepressant affected the maximal-tolerated volume (MTV) of the nutrient drink test although aggregate symptom scores improved compared to placebo (P=0.04). Patients with the combined EPS-PDS subtype (48%) had a lower MTV on the nutrient drink test compared to the EPS group at baseline (P=0.02). Postprandial bloating improved with both AMI (P=0.03) and ESC (P=0.02).

CONCLUSIONS

Amitriptyline (50 mg) improves FD symptoms but does not delay gastric emptying, even in patients with baseline delayed gastric emptying. GA improved with low-dose ADTx; the precise mechanism of action is unknown warranting further study.

Relationship of gastric emptying or accommodation with satiation, satiety, and postprandial symptoms in health

The contributions of gastric emptying (GE) and gastric accommodation (GA) to satiation, satiety, and postprandial symptoms remain unclear. We aimed to evaluate the relationships between GA or GE with satiation, satiety, and postprandial symptoms in healthy overweight or obese volunteers (total n = 285, 73% women, mean BMI 33.5 kg/m²): 26 prospectively studied obese, otherwise healthy participants and 259 healthy subjects with previous similar GI testing. We assessed GE of solids, gastric volumes, calorie intake at buffet meal, and satiation by measuring volume to comfortable fullness (VTF) and maximum tolerated volume (MTV) by using Ensure nutrient drink test (30 ml/min) and symptoms 30 min after MTV. Relationships between GE or GA with satiety, satiation, and symptoms were analyzed using Spearman rank (r_s ) and Pearson (R) linear correlation coefficients. We found a higher VTF during satiation test correlated with a higher calorie intake at ad libitum buffet meal (r_s = 0.535, P < 0.001). There was a significant inverse correlation between gastric half-emptying time (GE T_1/2) and VTF (r_s = -0.317, P < 0.001) and the calorie intake at buffet meal (r_s = -0.329, P < 0.001), and an inverse correlation between GE Tlag and GE25% emptied with VTF (r_s = -0.273, P < 0.001 and r_s = -0.248, P < 0.001, respectively). GE T_1/2 was significantly associated with satiation (MTV, R = -0.234, P < 0.0001), nausea (R = 0.145, P = 0.023), pain (R = 0.149, P = 0.012), and higher aggregate symptom score (R = 0.132, P = 0.026). There was no significant correlation between GA and satiation, satiety, postprandial symptoms, or GE. We concluded that GE of solids, rather than GA, is associated with postprandial symptoms, satiation, and satiety in healthy participants.NEW & NOTEWORTHY A higher volume to comfortable fullness postprandially correlated with a higher calorie intake at ad libitum buffet meal. Gastric emptying of solids is correlated to satiation (volume to fullness and maximum tolerated volume) and satiety (the calorie intake at buffet meal) and symptoms of nausea, pain, and aggregate symptom score after a fully satiating meal. There was no significant correlation between gastric accommodation and either satiation or satiety indices, postprandial symptoms, or gastric emptying.

Clinical assessment of gastric emptying and sensory function utilizing gamma scintigraphy: Establishment of reference intervals for the liquid and solid components of the Nottingham test meal in healthy subjects

BACKGROUND

Current investigations of stomach function are based on small test meals that do not reliably induce symptoms and analysis techniques that rarely detect clinically relevant dysfunction. This study presents the reference intervals of the modular "Nottingham test meal" (NTM) for assessment of gastric function by gamma scintigraphy (GSc) in a representative population of healthy volunteers (HVs) stratified for age and sex.

METHODS

The NTM comprises 400 mL liquid nutrient (0.75 kcal/mL) and an optional solid component (12 solid agar-beads (0 kcal). Filling and dyspeptic sensations were documented by 100 mm visual analogue scale (VAS). Gamma scintigraphy parameters that describe early and late phase Gastric emptying (GE) were calculated from validated models.

KEY RESULTS

Gastric emptying (GE) of the liquid component was measured in 73 HVs (male 34; aged 45±20). The NTM produced normal postprandial fullness (VAS ≥30 in 41/74 subjects). Dyspeptic symptoms were rare (VAS ≥30 in 2/74 subjects). Gastric emptying half-time with the Liquid- and Solid-component -NTM was median 44 (95% reference interval 28-78) minutes and 162 (144-193) minutes, respectively. Gastric accommodation was assessed by the ratio of the liquid-NTM retained in the proximal:total stomach and by Early phase emptying assessed by gastric volume after completing the meal (GCV0). No consistent effect of anthropometric measures on GE parameters was present.

CONCLUSIONS AND INFERENCES

Reference intervals are presented for GSc measurements of gastric motor and sensory function assessed by the NTM. Studies involving patients are required to determine whether the reference interval range offers optimal diagnostic sensitivity and specificity.

Effects of NK1 receptors on gastric motor functions and satiation in healthy humans: results from a controlled trial with the NK1 antagonist aprepitant

Aprepitant, an NK1 receptor antagonist, is approved for the treatment of chemotherapy-induced or postoperative emesis by blocking NK1 receptors in the brain stem vomiting center. The effects of NK1 receptors on gastric functions and postprandial symptoms in humans are unclear; a single, crossover study did not show a significant effect of aprepitant on gastrointestinal transit. Our aim was to compare, in a randomized, double-blind, placebo-controlled, parallel-group study (12 healthy volunteers per group), the effects of aprepitant vs. placebo on gastric emptying of solids (by scintigraphy) with a 320-kcal meal, gastric volumes (GVs; fasting and accommodation by single photon emission-computed tomography ), satiation [maximum tolerated volume (MTV)], and symptoms after a dyspeptogenic meal of Ensure. Aprepitant (125 mg on day 1, followed by 80 mg on days 2-5) or placebo, one tablet daily, was administered for 5 consecutive days. Statistical analysis was by unpaired rank sum test, adjusted for sex difference and body mass index. To assess treatment effects on symptoms, we incorporated MTV in the model. Aprepitant increased fasting, postprandial, and accommodation GV and tended to increase volume to fullness and MTV by ~200 kcal. However, aprepitant increased aggregate symptoms, nausea, and pain scores after ingestion the MTV of Ensure. There was no significant effect of aprepitant on gastric half-emptying time of solids. We conclude that NK1 receptors are involved in the control of GV and in determining postprandial satiation and symptoms. Further studies of the pharmacodynamics and therapeutic role of NK1 receptor antagonists in patients with gastroparesis and dyspepsia are warranted.NEW & NOTEWORTHY Aprepitant increases fasting, postprandial, and accommodation gastric volumes. Aprepitant increases volume to fullness and maximum tolerated volume during a nutrient drink test. NK1 receptors are involved in the control of gastric volume and in determining postprandial satiation and symptoms.

Influence of the Resected Gastric Volume on the Weight Loss After Laparoscopic Sleeve Gastrectomy

BACKGROUND

The relation between the resected gastric volume and the weight loss after laparoscopic sleeve gastrectomy appears conflicting in the literature. Both the residual and the resected volumes represent the total gastric volume, and if the weight loss is related to one of the two volumes, it should be related to the other. While some reports indicate that the weight loss is related to the resected gastric volume, others state that the weight loss is not related to the residual volume. The aim is to investigate the influence of the resected gastric volume on the weight loss after surgery.

METHODS

The study included 287 consecutive patients. Gastrectomy was performed encroaching over a 38-Fr calibrating tube all the way to the angle of His. Filling volume of the resected stomach, with tap water, was measured. Patients were analyzed into group 1 with BMI ≤50 kg/m(2) and group 2 >50 kg/m(2).

RESULTS

Females represented 74 % of cases. Mean age was 32.9 ± 9.5 years; preoperative BMI = 48.7 ± 7.9 kg/m(2). The mean resected gastric volume was 1525 ± 408 ml, and it was significantly lower in females compared to that in males (1443 ± 311 vs 1824 ± 502 ml, p < 0.001). Data were analyzed in two groups: group 1 with BMI ≤5050 kg/m(2) and group 2 >50 kg/m(2). Both groups were similar in preoperative BMI (p = 0.399) and excess weight percent (EW%) (p = 0.33). Group 2 had a resected gastric volume (1663 ± 424.7 ml) greater than that of group 1 (1440 ± 347 ml; p < 0.001). The percentage of excess weight loss (EWL%) was 57.9 ± 14.5 % at 6 months (62.7 ± 13.5 % vs 48.34 ± 11.29 %, p < 0.001), 77 ± 19 % at 12 months (84 ± 19.6 % vs 68 ± 14.2 %, p = 0.001), 76.6 ± 7.4 % at 18 months (79.7 ± 4.8 vs 74.7 ± 8.2 %, p = 0.5), and 75.8 ± 11.5 % at 24 months (81.7 ± 11.17 vs 70 ± 11 %, p = 0.8) (group 1 vs group 2, respectively). At 12 months, 86 % patients achieved more than 50 % EWL% (100 % of group 1 vs 60 % of group 2). Preoperative BMI correlated with resected gastric volume (r = 0.239, p = 0.004). In multiple regression, the initial BMI was a predictor of EWL% at 6 and 12 months (r partial = -0.65, p < 0.0001) while the resected gastric volume was not.

CONCLUSIONS

The resected gastric volume is related to the total gastric volume when the technique is standardized and the residual volume is calibrated using a consistent technique. It is not in itself a predictor of weight loss, but it is related to the initial BMI which predicts the weight loss.

Nutrient drink test: Normative values in Indian children

BACKGROUND

Nutrient drink test (NDT) is a simple, non-invasive method to assess gastric function including accommodation. However, data on normal satiety drink volume (SDV) in children is scanty with no information about postprandial symptoms (PPS). Our aims were to establish normal values of NDT in healthy children and evaluate its correlation with age, gender, and anthropometry.

METHODS

Six- to 18-year-old healthy children underwent the NDT. The nutrient drink (0.94 kcal/mL) was given at a constant rate of 15 mL/min in 6-12-year-old subjects and at 30 mL/min in 13-18-year-old subjects till satiety score of 5 was reached. Postprandial symptoms (30 min) of fullness, nausea, bloating, and pain were scored using a visual analogue scale (0-100 mm) individually and as aggregate score.

RESULTS

Sixty-seven children (40 boys, age 12 [6-18 years]) were enrolled. Median SDV was 360 [180-960 mL], higher in 13-18-year-olds in comparison to 6-12-year-old children (360 [240-1002] vs. 300 [148-960] mL; p=0.005). SDV showed significant correlation with age, weight, and height. SDV was higher in boys than girls (450 [240-1074] vs. 330 [240-480] mL; p=0.02) in the older children (13-18 y), but it was similar in the younger children. Mild fullness (40 [0-80]) was the only PPS seen in 85% children and none had pain. PPS were not different between boys and girls or younger and older children.

CONCLUSION

The study provides normative data of SDV and PPS by NDT in 6-18-year-old children. SDV correlated with age and was higher in adolescent boys than girls.

The Intragastric Pressure Measurement: A Novel Method to Assess Gastric Accommodation in Functional Dyspepsia Children

BACKGROUND

Impaired gastric accommodation (GA) is proposed as a main pathophysiological mechanism for functional dyspepsia (FD). At present, the gastric barostat is the criterion standard to measure GA. Hence, this procedure is invasive and it may alter gastric physiology. Recently, we proposed the measurement of intragastric pressure (IGP) by means of high-resolution manometry during nutrient intake as a potential alternative for assessing GA in adults.

OBJECTIVES

Our aim was first to study the feasibility of the IGP measurement with nutrient tolerance in children with FD and second to compare these results with young healthy adults.

METHODS

A high-resolution manometry probe and a feeding tube were positioned in the proximal stomach. The IGP was measured before and during intragastric infusion of a nutrient drink (ND, 300 kcal, 60 mL/min). Subjects were asked to score their satiation and epigastric symptoms. The test ended when the subjects scored maximal satiation.

RESULTS

A total of 15 healthy volunteers (HVs, 21.7 ± 4.7 years, 21.1 ± 0.3 kg/m) and 17 patients with FD (14.4 ± 0.7 years, 19.6 ± 0.7 kg/m) participated. Patients with FD experienced mainly from postprandial fullness (86%), epigastric pain (71%), and bloating (62%). In both groups, intragastric infusion of ND induced a drop in IGP (area above the IGP curve FD: -15.5 ± 3.5 mmHg vs HVs: -18.0 ± 8.7 mmHg; P = 0.57). Patients showed impaired nutrient tolerance compared with HVs (587.6 ± 80.2 vs 936 ± 66.2 kcal; P = 0.003). All patients and HVs tolerated the catheters and could finalize the study.

CONCLUSIONS

The measurement of IGP during intragastric ND infusion was well tolerated in children. Nutrient tolerance was reduced in children with FD compared with HVs. In the future, this may be a useful tool to assess GA accommodation and nutrient tolerance in children.

Endoscopic Sleeve Gastroplasty Alters Gastric Physiology and Induces Loss of Body Weight in Obese Individuals

BACKGROUND & AIMS

Although bariatric surgery is the most effective therapy for obesity, only a small proportion of candidates undergo this surgery. Endoscopic sleeve gastroplasty (ESG) is a minimally invasive procedure that reduces the size of the gastric reservoir. We investigated its durability and effects on body weight and gastrointestinal function in a prospective study of obese individuals.

METHODS

Twenty-five obese individuals (21 female; mean body mass index, 35.5 ± 2.6 kg/m²; mean age, 47.6 ± 10 years) underwent ESG with endoluminal creation of a sleeve along the gastric lesser curve from September 2012 through March 2015 at the Mayo Clinic in Rochester, Minnesota. Subjects were followed for a median period of 9 months. We measured changes in body weight and recorded adverse events; patients were assessed by endoscopy after 3 months. Four participants underwent pre-ESG and post-ESG analyses to measure solid and liquid gastric emptying, satiation (meal tolerance), and fasting and postprandial levels of insulin, glucose, and gut hormones.

RESULTS

Subjects had lost 53% ± 17%, 56% ± 23%, 54% ± 40%, and 45% ± 41% of excess body weight at 6, 9, 12, and 20 months, respectively, after the procedure (P < .01). Endoscopy at 3 months showed intact gastroplasty in all subjects. After ESG, physiological analyses of 4 participants showed a decrease by 59% in caloric consumption to reach maximum fullness (P = .003), slowing of gastric emptying of solids (P = .03), and a trend toward increased insulin sensitivity (P = .06). Three patients had serious adverse events (a perigastric inflammatory collection, a pulmonary embolism, and a small pneumothorax) but made full recoveries with no need for surgical interventions. No further serious adverse events occurred after the technique was adjusted.

CONCLUSIONS

ESG delays gastric emptying, induces early satiation, and significantly reduces body weight. ESG could be an alternative to bariatric surgery for selected patients with obesity. ClincialTrials.gov number: NCT 01682733.

Measurement of Gastrointestinal and Colonic Motor Functions in Humans and Animals

Accurately measuring the complex motor behaviors of the gastrointestinal tract has tremendous value for the understanding, diagnosis and treatment of digestive diseases. This review synthesizes the literature regarding current tests that are used in both humans and animals. There remains further opportunity to enhance such tests, especially when such tests are able to provide value in both the preclinical and the clinical settings.

Development and validation of a large, modular test meal with liquid and solid components for assessment of gastric motor and sensory function by non-invasive imaging

BACKGROUND

Current investigations of stomach function are based on small test meals that do not reliably induce symptoms and analysis techniques that rarely detect clinically relevant dysfunction. This study introduces the large 'Nottingham Test Meal' (NTM) for assessment of gastric motor and sensory function by non-invasive imaging.

METHODS

NTM comprises 400 mL liquid nutrient (0.75 kcal/mL) and 12 solid agar-beads (0 kcal) with known breaking strength. Gastric fullness and dyspeptic sensations were documented by 100 mm visual analogue scale (VAS). Gastric emptying (GE) were measured in 24 healthy volunteers (HVs) by gastric scintigraphy (GS) and magnetic resonance imaging (MRI). The contribution of secretion to gastric volume was assessed. Parameters that describe GE were calculated from validated models. Inter-observer agreement and reproducibility were assessed.

KEY RESULTS

NTM produced moderate fullness (VAS ≥30) but no more than mild dyspeptic symptoms (VAS <30) in 24 HVs. Stable binding of meal components to labels in gastric conditions was confirmed. Distinct early and late-phase GE were detected by both modalities. Liquid GE half-time was median 49 (95% CI: 36-62) min and 68 (57-71) min for GS and MRI, respectively. Differences between GS and MRI measurements were explained by the contribution of gastric secretion. Breaking strength for agar-beads was 0.8 N/m(2) such that median 25 (8-50) % intact agar-beads and 65 (47-74) % solid material remained at 120 min on MRI and GS, respectively. Good reproducibility for liquid GE parameters was present and GE was not altered by agar-beads.

CONCLUSIONS & INFERENCES

The NTM provided an objective assessment of gastric motor and sensory function. The results were reproducible and liquid emptying was not affected by non-nutrient agar-beads. The method is potentially suitable for clinical practice.

Upper gastrointestinal sensitivity to meal-related signals in adult humans - relevance to appetite regulation and gut symptoms in health, obesity and functional dyspepsia

Both the stomach and small intestine play important roles in sensing the arrival of a meal, and its physico-chemical characteristics, in the gastrointestinal lumen. The presence of a meal in the stomach provides a distension stimulus, and, as the meal empties into the small intestine, nutrients interact with small intestinal receptors, initiating the release of gut hormones, associated with feedback regulation of gastrointestinal functions, including gut motility, and signaling to the central nervous system, modulating eating behaviours, including energy intake. Lipid appears to have particularly potent effects, also in close interaction with, and modulating the effects of, gastric distension, and involving the action of gut hormones, particularly cholecystokinin (CCK). These findings have not only provided important, and novel, insights into how gastrointestinal signals interact to modulate subjective appetite perceptions, including fullness, but also laid the foundation for an increasing appreciation of the role of altered gastrointestinal sensitivities, e.g. as a consequence of excess dietary intake in obesity, or underlying the induction of gastrointestinal symptoms in functional dyspepsia (a condition characterized by symptoms, including bloating, nausea and early fullness, amongst others, after meals, particularly those high in fat, in the absence of any structural or functional abnormalities in the gastrointestinal tract). This paper will review the effects of dietary nutrients, particularly lipid, on gastrointestinal function, and associated effects on appetite perceptions and energy intake, effects of interactions of gastrointestinal stimuli, as well as the role of altered gastrointestinal sensitivities (exaggerated, or reduced) in eating-related disorders, particularly obesity and functional dyspepsia.

Pharmacological, Pharmacokinetic, and Pharmacogenomic Aspects of Functional Gastrointestinal Disorders

This article reviews medications commonly used for the treatment of patients with functional gastrointestinal disorders. Specifically, we review the animal models that have been validated for the study of drug effects on sensation and motility; the preclinical pharmacology, pharmacokinetics, and toxicology usually required for introduction of new drugs; the biomarkers that are validated for studies of sensation and motility endpoints with experimental medications in humans; the pharmacogenomics applied to these medications and their relevance to the FGIDs; and the pharmacology of agents that are applied or have potential for the treatment of FGIDs, including psychopharmacologic drugs.

Gastrointestinal traits: individualizing therapy for obesity with drugs and devices

BACKGROUND AND AIMS

The aims of this article were to review the discrepancy between numbers of people requiring weight loss treatment and results and to assess the potential effects of pharmacologic treatments (recently approved for obesity) and endoscopically deployed devices on quantitative GI traits in development for obesity treatment.

METHODS

We conducted a review of relevant literature to achieve our objectives.

RESULTS

The 2013 guidelines increased the number of adults recommended for weight loss treatment by 20.9% (116.0 million to 140.2 million). There is an imbalance between efficacy and costs of commercial weight loss programs and drug therapy (average weight loss about 5 kg). The number of bariatric procedures performed in the United States has doubled in the past decade. The efficacy of bariatric surgery is attributed to reduction in the volume of the stomach, nutrient malabsorption with some types of surgery, increased postprandial incretin responses, and activation of farnesoid X receptor mechanisms. These GI and behavioral traits identify sub-phenotypes of obesity, based on recent research.

CONCLUSIONS

The mechanisms or traits targeted by drug and device treatments include centrally mediated alterations of appetite or satiation, diversion of nutrients, and alteration of stomach capacity, gastric emptying, or incretin hormones. Future treatment may be individualized based on quantitative GI and behavioral traits measured in obese patients.

Exenatide in obesity with accelerated gastric emptying: a randomized, pharmacodynamics study

Obesity is associated with differences in satiety, gastric emptying (GE), gastric volume, and psychological traits. Exenatide, a short-acting glucagon-like peptide 1 (GLP-1) receptor agonist, is associated with variable weight loss. We compared the effects of exenatide, 5 μg, and placebo SQ, twice daily for 30 days on GE of solids and liquids (scintigraphy), satiety (ad libitum buffet meal), satiation (nutrient drink test, maximum tolerated volume [MTV]), and weight loss in 20 participants with documented accelerated GE of solids (T1/2 < 90 min). Exenatide delayed GE of solids (T1/2 [Δ] 86 min relative to placebo, P < 0.001) and reduced calorie intake at buffet meal ([Δ] 129 kcal compared to placebo). Median weight loss was -0.95 kg (IQR -0.7 to -2.1) for exenatide and -0.55 kg (0.3 to -2.1) for placebo (P = 0.23); 80% of exenatide group had documented reduction in weight. In the exenatide treatment group, there was an inverse correlation between gastric emptying T1/2 and MTV (R = -0.548, P = 0.089). The univariate association of weight change with posttreatment MTV was borderline (Rs = 0.43, P = 0.06); in the multiple regression model, posttreatment MTV was associated with weight change (P = 0.047). The effect of the short-acting GLP-1 receptor agonist, exenatide, on GE is associated with the change in food intake, and the latter impacts weight loss in response to exenatide treatment.

Effect of Amitriptyline and Escitalopram on Functional Dyspepsia: A Multicenter, Randomized Controlled Study

BACKGROUND & AIMS

Antidepressants are frequently prescribed to treat functional dyspepsia (FD), a common disorder characterized by upper abdominal symptoms, including discomfort or postprandial fullness. However, there is little evidence of the efficacy of these drugs in patients with FD. We performed a randomized, double-blind, placebo-controlled trial to evaluate the effects of antidepressant therapy on symptoms, gastric emptying (GE), and meal-induced satiety in patients with FD.

METHODS

We performed a study at 8 North American sites of patients who met the Rome II criteria for FD and did not have depression or use antidepressants. Patients (n = 292; 44 ± 15 years old, 75% were female, 70% with dysmotility-like FD, and 30% with ulcer-like FD) were randomly assigned to groups given placebo, 50 mg amitriptyline, or 10 mg escitalopram for 10 weeks. The primary end point was adequate relief of FD symptoms for ≥5 weeks of the last 10 weeks (of 12). Secondary end points included GE time, maximum tolerated volume in Nutrient Drink Test, and FD-related quality of life.

RESULTS

An adequate relief response was reported by 39 subjects given placebo (40%), 51 given amitriptyline (53%), and 37 given escitalopram (38%) (P = .05, after treatment, adjusted for baseline balancing factors including all subjects). Subjects with ulcer-like FD given amitriptyline were >3-fold more likely to report adequate relief than those given placebo (odds ratio = 3.1; 95% confidence interval: 1.1-9.0). Neither amitriptyline nor escitalopram appeared to affect GE or meal-induced satiety after the 10-week period in any group. Subjects with delayed GE were less likely to report adequate relief than subjects with normal GE (odds ratio = 0.4; 95% confidence interval: 0.2-0.8). Both antidepressants improved overall quality of life.

CONCLUSIONS

Amitriptyline, but not escitalopram, appears to benefit some patients with FD, particularly those with ulcer-like (painful) FD. Patients with delayed GE do not respond to these drugs. ClinicalTrials.gov ID: NCT00248651.

Association of UCP-3 rs1626521 with obesity and stomach functions in humans

OBJECTIVE

To examine the association of gene variants of uncoupling proteins (UCP)-2 and -3 with obesity and gastrointestinal (GI) traits.

METHODS

In 255 overweight or obese adults, the associations of gene variants in UCP-2 (-3474, rs659366) and UCP-3 (rs1626521, rs2075577, rs15763) with body weight (BW) and GI traits were studied. Gene variants were genotyped by TaqMan® assay. The associations of genotypes with BW and GI traits (gastric emptying, gastric volume, satiety by buffet meal, satiation by nutrient drink test and GI hormones) were assessed using ANOVA corrected for false detection rate (FDR).

RESULTS

A novel UCP-3 gene variant, rs1626521, was identified; it was associated with BW (P = 0.039), waist circumference (P = 0.035), and significantly higher postprandial gastric volume (P = 0.003) and calories ingested at buffet meal (P = 0.006, both significant with FDR). In a subgroup of 11 participants, rs1626521 was also associated with reduced mitochondrial bioenergetics efficiency in skeletal muscle (P = 0.051). In an in vitro study in HEK293 cells, rs1626521 reduced UCP-3 protein expression (P = 0.049). Associations detected between other genotypes and GI traits were nonsignificant with FDR.

CONCLUSIONS

A newly identified functional variant (rs1626521) in UCP-3 affects postprandial gastric functions and satiety and may contribute to weight gain and alter human mitochondrial function.