Society: AGA

Introduction: Patients with upper gastrointestinal (UGI) symptoms of abdominal pain, nausea, vomiting, and bloating often complain within the postprandial period. These symptoms overlap in gastroparesis (GP) and functional dyspepsia (FD), with the only distinction of gastric emptying delay being the main facet in clinical evaluation that separates the two entities. The small bowel postprandial response, an increase in contractile activity following meal intake, is known to be blunted in GP compared to healthy volunteers (HV) as measured by wireless motility capsule (WMC). This neuro-mediated reflex has not been evaluated in those with FD. The primary aim of the study was to assess the small bowel postprandial response in FD compared to GP and HV.
Methods: WMC data of HV and subjects with UGI symptoms suggestive of GP from prior clinical trials were analyzed. A gastric emptying time (GET) cut-off of 5 hours was used to classify symptomatic subjects as GP or FD. All subjects ingested a 250 cc standardized Ensure® meal after a 6-hour fast post-WMC ingestion. Area under the pressure curve (AUC), a measure of both contractile frequency and amplitude, data was extracted from a 20 minutes pre-prandial baseline and three consecutive 20-minute postprandial time periods to allow for granular assessment of contractility during the first 60-minute postprandial period. Comparison of postprandial windows to baseline and comparison of respective windows between subject groups was performed using a paired and unpaired t-tests, respectively. Significance level was defined as p< 0.05.
Key Results: 107 HV, 18 FD and 24 GP subjects were analyzed. All subjects showed a significant postprandial increase in AUC in all periods compared to baseline (p < 0.05). HV showed a robust meal response from meal ingestion to 40 minutes which expectedly decreases from 40 to 60 minutes postprandially (Figure 1). GP had a blunted meal response in all post-prandial time periods compared to HV (Figure 1). FD had a postprandial response pattern distinct from HV and GP, showing some intermediate blunting immediately after the meal but with distinctly increased contractile activity later compared to GP (Figure 1).
Conclusion: FD subjects have small bowel motor component abnormalities during the meal response without delayed gastric emptying. The patterns appear to be intermediate blunting (within the first 20-minutes postprandially) of the small bowel meal response in between a healthy and gastroparetic pattern. These motility abnormalities in the small bowel could be contributing to symptoms in FD or be a consequence of neuro-enteric dysfunction in FD patients.

Figure 1. Comparison of the area under the curve (AUC) of the small bowel pressure profile before and after a standardized meal intake between healthy, functional dyspepsia (FD), and gastroparesis (GP) subjects.

Background and aims: Epigastric pain is one of the major symptoms in patients with functional dyspepsia (FD) that affects up to 16% of the general population. Currently treatment options for epigastric pain in FD are limited. Our previous studies have shown promising effects of auricular vagus nerve stimulation (aVNS) for treating pain in both animal model of gastric hyperalgesia (GH) and patients with FD. Duodenal epithelial barrier impairment and immune activation are believed to play an important role in the pathogenesis of FD. This study aimed to explore analgesic effects and autoimmune mechanisms of aVNS in treating visceral pain in a rodent model of GH.
Methods: GH was induced by the gastric iodoacetamide (IA) treatment in the neonatal stage. Control rats (n=5) received neonatal vehicle treatment. The IA-treated rats in adulthood were randomized to Sham (no stimulation output, n=10) or aVNS (n=10), 1 hour daily for 10 days using parameters previously shown to suppress visceral pain. Gastric visceromotor reflex to graded gastric distensions (GD) was assessed by electromyogram (EMG). Autonomic functions were assessed by the spectral analysis of heart rate variability (HRV) to derive the low frequency (LF, reflecting mainly sympathetic activity) and high frequency (HF, reflecting vagal activity) components. Duodenal tissues were collected for the assessment of mucosal barrier function by the measurement of transepithelial electrical resistance (TEER) and the measurement of tight junction protein expression using Western blot. Duodenum mast cell activity was accessed by tryptase concentration normalized with tissue weight.
Results: 1) Compared with sham-aVNS, aVNS resulted in a decrease in the EMG response to GD, at 40, 60 and 80mmHg (P<0.01 for all) and mast cell activity accessed by tryptase concentration (10.3±3.6 vs. 14.9±5.0 ug/ml/mg, P=0.05), and an increase in duodenum mucosal integrity assessed by TEER (49.6±14.1 vs. 33.2±13.5 Ω.cm², P=0.03), the expression of duodenal tight junction ligandins occludin by 4.5 fold (P=0.026) and vagal efferent activity (HF: 0.52±0.24 vs. 0.33±0.13, P<0.05; LF/HF: 1.30±1.05 vs. 2.52±1.47, P<0.05) in the IA-treated rats. 2) Moreover, the aVNS-treated GH rats showed values comparable to the normal controls in mast cell activity (10.3±3.6 vs. 10.4±2.9 ug/ml/mg, P=0.94), TEER (49.6±14.1 vs. 50.6±5.5, P=0.87), protein expression of occludin (P=0.36) and vagal activity (HF: 0.52±0.24 vs. 0.58±0.17, P=0.62; LF/HF: 1.30±1.05 vs. 0.89±0.73, P=0.41), suggesting normalization of these activities/functions.
Conclusion: aVNS ameliorates gastric hypersensitivity by improving duodenal barrier function and structure possibly mediated via the autoimmune mechanisms.

Introduction:
Female gender has been shown to be a risk factor for gastroparesis, functional dyspepsia, and GERD. There was evidence that estrogen and progesterone can contribute to delayed gastric emptying. However, it is unclear if oral contraceptives (OCP) and hormone replacement therapy (HRT) would increase the risks of gastroparesis (GP) and functional dyspepsia (FD). The aim of the study was to evaluate the risks of developing common upper gastrointestinal disorders in patients who were on OCP and HRT.

Material and Methods:
A population based cohort analysis was performed using TriNetX. We selected adult female patients who were taking oral contraceptives. We also selected female patients aged 50 and above who were on HRT. The control group consists of adult female patients who received intrauterine device (IUD) for birth control. Propensity score matching was performed to adjust for age, race, ethnicity, diabetes, BMI and hemoglobin A1C. We compared the incidence of GP, FD, gastroesophageal reflux disease (GERD), Barrett’s esophagus (BE), esophagitis in OCP cohort with IUD cohort. Similar comparison was performed for HRT cohort and IUD cohort.

Results:
We identified a total of 3,065,444 patients who were taking OCPs, 240,420 patients who were on HRT, and 513,883 patients who received IUD insertion. Patients who were on OCPs were at higher risks for developing GP (OR 1.37-1.64), FD (OR 1.11-1.23), GERD (OR 1.15-1.20), BE (1.03-1.40), and esophagitis (OR 1.03-1.15) than patients who received IUD insertion. Similarly, patients who received HRT were also at higher risks for developing GP (OR 1.64-2.60), FD (OR 1.40-1.83), GERD (OR 1.65-1.86), BE (1.17-2.05), and esophagitis (OR 1.55-2.03) than patients who received IUD insertion.

Conclusions:
Oral contraceptives and hormone replacement therapy are associated with higher risks of developing upper gastrointestinal disorders than patients who received IUD insertion. Further research would be necessitated to determine the role of estrogen and progesterone on the upper gastrointestinal tract.

Table 1 Upper gastrointestinal disorders in patientson OCP and HRT

Table 1 Upper gastrointestinal disorders in patientson OCP and HRT

Background
Gastric emptying testing (GET) is used to assess gastric motility, however is non-specific and insensitive for neuromuscular disorders. Gastric Alimetry® is a new medical device combining non-invasive gastric electrophysiological mapping and validated symptom profiling. This study assessed patient-specific phenotyping using Gastric Alimetry with comparison to GET.
Methods
Patients with chronic gastroduodenal symptoms underwent simultaneous GET and Gastric Alimetry. Tests comprised a 30-minute baseline, 99mTC-labelled egg meal, and 4-hour postprandial recording. Results were referenced to normative ranges. Symptoms were profiled in the validated Gastric Alimetry App, phenotyped with rule-based criteria, and compared to questionnaires. Three symptom profiles were phenotyped: i) continuous (symptoms do not correlate with meal or gastric activity); ii) gastric sensorimotor (symptoms increase within 30 minutes of the meal and decay as gastric activity decreases); and iii) Other (symptoms that do not fit the other two symptom profiles).
Results
75 patients with chronic gastroduodenal symptoms were assessed; 77% female, median age 43, median BMI 24.0. Motility abnormality detection rates (Figure 1A) were: GET 22.7% (14 delayed, 3 rapid); Gastric Alimetry spectral analysis 33.3% (14 dysrhythmic / low amplitude; 5 high amplitude; 6 abnormal frequency); combined yield 42.7%. All groups showed similar symptom profiles and did not correlate with specific Rome criteria or health psychology (p>0.05). Gastric Alimetry symptom phenotypes (Figure 1A) were: gastric sensorimotor 17%; continuous 30%; other 53%. The sensorimotor phenotype correlated strongly with gastric amplitude (median r=0.61 vs r=0.08 and r=0.06 respectively; p=0.0002). Only the continuous phenotype correlated with depression and anxiety (p<0.05), while Rome IV Criteria did not correlate (p>0.05). Delayed emptying was not predictive of specific Gastric Alimetry phenotypes (Figure 1B).
Conclusion
Gastric Alimetry generated a higher yield for motility abnormalities than GET in patients with chronic gastroduodenal symptoms. Gastric Alimetry also identified patient-specific symptom phenotypes, showing correlations with health psychology variables not observed with Rome IV and GET. GET and Gastric Alimetry assess different aspects of gastric function, indicating these tests may have complementary roles.

Peng Du

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