Altered Vagal Signaling and Its Pathophysiological Roles in Functional Dyspepsia

The effect of corticotropin-release hormone on duodenal permeability and immune activation in healthy volunteers in a double-blind placebo-controlled study

In functional dyspepsia, increased gut permeability, low-grade inflammation, and altered sensorimotor function have been reported. Both stress and corticotropin-release hormone (CRH) have been shown to increase small bowel permeability in a mast-cell-dependent manner. Moreover, eosinophil-derived CRH has been implicated in mast cell activation. The aim of this study was to evaluate whether CRH administration alters duodenal permeability and immune activation in healthy volunteers (HVs). An intravenous bolus of 100-µg CRH or placebo was administered in HVs in a crossover, double-blind, randomized manner. Two hours later, a gastroscopy was performed to measure permeability in Ussing chambers and to count mast cells and eosinophils on duodenal biopsies. Supernatant was assessed for eosinophil-derived neurotoxin (EDN), tryptase, and chymase. In addition, CRH was administrated ex vivo to baseline biopsies pretreated with or without lodoxamide. Results are described as means ± SD. P values < 0.05 were considered significant. Twenty HVs completed the study. Mast cell or eosinophil counts were not significantly altered after CRH versus Placebo (respectively P = 0.31 and P = 0.069). Tryptase, but not chymase, significantly decreased after CRH (respectively P = 0.037 and P = 0.44) with a trend for a decrease in EDN (P = 0.053). Permeability was unaltered comparing both conditions. Ex vivo, transepithelial electrical resistance significantly decreased after CRH exposure compared with baseline (P = 0.010), which was not prevented by pretreatment with lodoxamide. In vivo CRH administration reduced tryptase levels in the supernatant of duodenal biopsies without affecting permeability, whereas ex vivo duodenal permeability increased regardless of mast cell stabilization. These results suggest the involvement of mast cells in regulating gut permeability in HVs in response to CRH, possibly influenced by in vivo compensatory mechanisms.NEW & NOTEWORTHY Our investigation breaks new ground by directly examining the effects of corticotropin-release hormone (CRH) on duodenal alterations, including permeability and immune activation, in healthy subjects. Intriguingly, our findings highlight disparities between ex vivo and in vivo pathways affecting duodenal permeability, offering novel insights into the potential pathophysiology of CRH on the duodenum.

Exploring the Connection between Sleep Disorders, Emotional Distress, and Quality of Life in Functional Dyspepsia

OBJECTIVE

This study aimed to explore the factors influencing sleep disorders in patients with functional dyspepsia.

METHODS

A total of 100 patients with functional dyspepsia admitted to Gong An County People's Hospital from 2020 to 2021 were selected. According to the Pittsburgh Sleep Quality Index (PSQI), those with a score ≥8 were classified as the occurrence group, whereas those with a score <8 were classified as the non-occurrence group. Clinical and disease characteristics of patients were collected. Logistic regression analysis was used to identify influencing factors. The emotional distress and quality of life of patients with different severities of sleep disorders were compared. Pearson's correlation was used to identify the relationship between the degree of sleep disorders and various indicators.

RESULTS

Out of 100 patients with functional dyspepsia, 58 (58.00%) had varying degrees of sleep disturbance. Logistic regression analysis showed that factors measured by the Self-Rating Anxiety Scale (SAS) (odds ratio [OR] = 3.088, p = 0.007), Self-Rating Depression Scale (SDS) (OR = 3.268, p = 0.005), Perceived Stress Scale (PSS) (OR = 2.659, p = 0.019), and Functional Digestive Disorders Quality of Life (FDDQL) questionnaire (OR = 2.591, p = 0.022) were the main factors influencing sleep disturbance. Pearson correlation analysis suggested that SAS (r = 0.677, p < 0.001), SDS (r = 0.623, p < 0.001), and PSS (r = 0.550, p < 0.001) scores were positively correlated with the severity of sleep disturbance, whereas FDDQL (r = -0.623, p < 0.001) score was negatively correlated with the severity of sleep disturbance.

CONCLUSION

Functional dyspepsia patients are prone to varying degrees of sleep disorders, which are closely related to emotional distress and quality of life. Clinical interventions can be developed in advance to stabilize patient emotions and improve their quality of life.

Pregnancy and a high-fat, high-sugar diet each attenuate mechanosensitivity of murine gastric vagal afferents, with no additive effects

Gastric vagal afferents (GVAs) sense food-related mechanical stimuli and signal to the CNS to initiate meal termination. Pregnancy and diet-induced obesity are independently associated with dampened GVA mechanosensitivity and increased food intake. Whether a high-fat, high-sugar diet (HFHSD) impacts pregnancy-related adaptations in GVA signalling is unknown and was investigated in this study. Three-week-old female Glu Venus-expressing mice, on a C57BL/6 background, were fed standard laboratory diet (SLD) or HFHSD for 12 weeks, and then half of each group were mated to generate late pregnant (Day 17.5; P-SLD N = 12, P-HFHSD N = 14) or non-pregnant (NP-SLD N = 12, NP-HFHSD N = 16) groups. Body weight and food intake were monitored in Promethion metabolic cages from before mating until Day 17.5 of pregnancy or equivalent ages in non-pregnant mice, prior to tissue collection at 07.00 h for in vitro single fibre GVA recording and gene expression analysis. Pregnant mice gained more weight than non-pregnant mice but weight gain was unaffected by diet. By mid-pregnancy, light-phase food intake (kJ and g) was higher in pregnant than in non-pregnant mice (each P < 0.001) due to larger meals (kJ and g, each P < 0.001), irrespective of diet. Pregnancy and HFHSD-feeding reduced tension-sensitive GVA mechanosensitivity (each P < 0.01), but pregnancy did not further downregulate GVA stretch responses within HFHSD mice (P = 0.652). Nodose ganglia growth hormone receptor mRNA abundance was upregulated in pregnancy, possibly contributing to lower GVA mechanosensitivity during pregnancy in SLD mice. Larger light-phase meals in pregnant compared to non-pregnant HFHSD mice may therefore reflect the downregulation of other satiety pathways. KEY POINTS: Gastric vagal afferents (GVAs) regulate food intake by sensing the arrival and quantity of food and communicating this information to the brain. In standard laboratory diet (SLD) mice, gastric tension-sensitive vagal afferent mechanosensitivity was attenuated in pregnant compared to non-pregnant mice, which is concurrent with increases in total food intake and meal size. Nodose ganglia growth hormone receptor mRNA abundance was increased in pregnancy, possibly accounting for attenuated GVA mechanosensitivity in pregnant SLD mice. In non-pregnant mice, tension-sensitive GVA mechanosensitivity was selectively attenuated in high-fat, high-sugar diet (HFHSD) compared to SLD mice. Despite this, HFHSD mice ate less food and smaller meals compared to the SLD mice, suggesting other satiety mechanisms are limiting food intake. Despite higher food intake, there was no further reduction in mechanosensitivity in pregnant HFHSD mice compared to non-pregnant HFHSD mice and further studies are required to increase understanding of food intake regulation across pregnancy.

Investigating the modulation of gastric sensations and disposition toward food with taVNS

Interoception, the perception of visceral sensations, is key for several survival functions, including those related to feeding behavior. Sensations of hunger and satiety are mediated by gastric signals transmitted via the vagus nerve to the Nucleus of Solitary Tract. Transcutaneous auricular vagus nerve stimulation (taVNS) has been shown to modulate brain-viscera communication and to impact interoceptive processing in the cardiac domain. Yet, its effect on gastric interoception remains unclear. The aim of this study was to investigate taVNS' modulatory effects on gastric interoception using the Water Load Test-II (WLT-II) and its impact on food-related dispositions through a disposition and willingness to eat task (DWET). Participants underwent active or sham taVNS while performing the WLT-II and DWET. Results showed no significant difference in gastric interoceptive accuracy and amount of water ingested between taVNS groups. However, we found a significant reduction in food liking after the fullness phase of the WLT-II in the active (vs sham) taVNS group, suggesting an influence of vagal activation in the inhibition of food enjoyment when satiated. These findings suggest that, while taVNS may not directly enhance gastric interoceptive accuracy at a conscious level, it influences food-related dispositions, likely by modulating the processing of gastric signals. Further research exploring the intricate relationship between vagal modulation, interoceptive abilities and eating behaviors is warranted to elucidate the underlying mechanisms and, possibly, develop targeted interventions for eating disorders.

Interaction of the Vagus Nerve and Serotonin in the Gut-Brain Axis

The gut-brain axis represents an important bidirectional communication network, with the vagus nerve acting as a central conduit for peripheral signals from the various gut organs to the central nervous system. Among the molecular mediators involved, serotonin (5-HT), synthesized predominantly by enterochromaffin cells in the gut, plays a pivotal role. Gut-derived serotonin activates vagal afferent fibers, transmitting signals to the nucleus tractus solitarius (NTS) and modulating serotonergic neurons in the dorsal raphe nucleus (DRN) as well as the norepinephrinergic neurons in the locus coeruleus (LC). This interaction influences emotional regulation, stress responses, and immune modulation. Emerging evidence also highlights the role of microbial metabolites, particularly short-chain fatty acids (SCFAs), in enhancing serotonin synthesis and vagal activity, thereby shaping gut-brain communication. This review synthesizes the current knowledge on serotonin signaling, vagal nerve pathways, and central autonomic regulation, with an emphasis on their implications for neuropsychiatric and gastrointestinal disorders. By elucidating these pathways, novel therapeutic strategies targeting the gut-brain axis may be developed to improve mental and physical health outcomes.

Reduced Gastric Mucosal Nerve Density in Functional Dyspepsia: Clinical Significance and Functional Correlation

INTRODUCTION

The aim of this study was to quantitatively examine gastric mucosal nerve density (GMND) in patients with functional dyspepsia (FD) and analyzed its clinical correlation.

METHODS

We prospectively enrolled 35 patients with FD and 16 age-matched and gender-matched healthy controls for comparison of GMND on endoscopic biopsy, scores of Gastroparesis Cardinal Symptom Index, and gastric emptying scintigraphy.

RESULTS

Patients with FD had lower GMND than the controls in gastric antrum, body, and fundus. GMND was inversely correlated with the Gastroparesis Cardinal Symptom Index scores, but not correlated with gastric emptying scintigraphy parameters.

DISCUSSION

GMND was reduced in FD and inversely correlated with the symptom severity.

The Interactions Between Diet and Gut Microbiota in Preventing Gestational Diabetes Mellitus: A Narrative Review

Recent studies have revealed that dysbiosis, defined as alterations in gut microbiota, plays an important role in the development and the progression of many non-communicable diseases, including metabolic disorders, such as type 2 diabetes mellitus and gestational diabetes mellitus (GDM). The high frequency of GDM makes this disorder an important public health issue, which needs to be addressed in order to reduce both the maternal and fetal complications that are frequently associated with this disease. The studies regarding the connections between gut dysbiosis and GDM are still in their early days, with new research continuously emerging. This narrative review seeks to outline the mechanisms through which a healthy diet that protects the gut microbiota is able to prevent the occurrence of GDM, thus providing medical nutritional therapeutic perspectives for the management of GDM.

Acupuncture improves the symptoms, serum ghrelin, and autonomic nervous system of patients with postprandial distress syndrome: a randomized controlled trial

BACKGROUND

Whether gastrointestinal hormones in patients with postprandial distress syndrome (PDS) are altered by acupuncture, and whether such alterations are related to the autonomic nervous system (ANS), remains an open question.

OBJECTIVE

This study aims to investigate the effects of acupuncture on symptoms, serum hormones, and ANS in PDS patients.

METHODS

This randomized controlled clinical trial was conducted at Beijing Hospital of Traditional Chinese Medicine affiliated with Capital Medical University. Sixty-two PDS patients were randomly assigned equally to acupuncture or sham acupuncture arm (3 sessions per week for 4-week). The main outcome measures which were evaluated at baseline and 4-week included cardinal symptoms, serum hormones including ghrelin, vasoactive intestinal peptide (VIP), substance P (SP), and ANS.

RESULTS

Among the 62 randomly assigned participants, 51 (82%) were included in the baseline characteristics and outcome analysis. Gastrointestinal symptoms including response rate (p = 0.001) and dyspepsia symptom severity (p = 0.002) were significantly improved after acupuncture treatment. Serum ghrelin concentration was significantly higher in acupuncture group than in sham acupuncture group (8.34 ± 3.00 ng/ml versus 6.52 ± 2.00 ng/ml, p = 0.022) after 4-week treatment, instead of VIP and SP (p > 0.05). The acupuncture group had significantly higher vagal activity, showing with increasing of high-frequency component (HF, p ≤ 0.001) and decreasing of the ratio of low-frequency and HF (p ≤ 0.001). In relationship analysis, the HF component exhibited a significant inverse correlation with symptom severity (R = - 0.501, p ≤ 0.001), but not with ghrelin level (R = 0.026, p = 0.865).

CONCLUSION

Acupuncture may improve the symptoms and increase the ghrelin level of PDS patients, the therapeutic effect of acupuncture was associated with the alteration of vagal activity.

TRIAL REGISTRATION

The trial is registered with the ISRCTN registry, ISRCTN12511434. Registered 31 March 2017, https://www.isrctn.com/ .

Comprehensive Investigation of Homology and Heterogeneity Between Aurantii Fructus and Aurantii Fructus Immaturus Using Chemometrics Combined with Network Pharmacology

Aurantii Fructus (AF) and Aurantii Fructus Immaturus (AFI) are distinct herbs outlined by the Chinese Pharmacopoeia. They are sourced from the same plant but harvested at different times, resulting in differences in efficacy. It is important to avoid mixing them clinically and to distinguish between the two. Furthermore, dissimilar cultivation conditions may cause variability in the quality of herbs, so it is vital to differentiate drugs from dissimilar origins. In this study, two plants, AF and AFI from different provinces, were comparatively analyzed based on High Performance Liquid Chromatography (HPLC) fingerprints and classified using chemometric methods. The results indicate that the two medicines can be clearly distinguished. Also, AF and AFI grown in different locations can be distinguished. Ten chemical markers were screened, and their variations were determined, including eriocitrin, narirutin, naringin, meranzin hydrate, naringenin, hesperidin, nobiletin, tangeretin, neohesperidin, and poncirin. Subsequent network pharmacology correlated the screened chemical components with the biological network of the organism. The material basis of the difference in efficacy of the two homologous herbs was explored from the perspective of changes in chemical composition. This study provides a reference for formulating quality evaluation standards for AF and AFI and lays a foundation for the efficacy-related quality research of the two.

Influence of autonomic nervous dysfunction on eating during hemodialysis sessions: An observational study

Although some studies have indicated that eating during hemodialysis may induce hypotension and cardiovascular events, some patients still consume food during their treatment. This prospective study was conducted to determine whether the need to eat during hemodialysis treatment was related to abnormal glucose metabolism and autonomic nerve dysfunction. Seventy patients were enrolled in this study, and their demographic features and various laboratory parameters were analyzed. At each routine hemodialysis visit, predialysis, intradialysis, and postdialysis blood pressure measurements were systematically conducted. A 24-hour ambulatory electrocardiogram (ECG) was performed during the hemodialysis interval, and heart rate variability (HRV) values were calculated. Additionally, whether the patients ate during the hemodialysis treatments was recorded. Another 20 people who underwent physical examinations during the same period and were matched for sex and age were included in the control group. The HRV values of the hemodialysis patients were generally lower than those of the control group. Univariate analysis revealed significant differences in sex, age, calcium antagonist use, blood calcium levels, insulin levels, diastolic blood pressure (DBP) measurements, and HRV indices between hemodialysis patients who ate and those who did not eat during hemodialysis (P < .05), whereas there were no significant differences in diabetes status or in the hemoglobin, albumin, blood glucose and C-peptide levels (P > .05). Multivariate analysis revealed that low values for very low frequency (VLF) and postdialysis DBP were risk factors for fasting intolerance during hemodialysis treatments. Autonomic dysfunction may affect whether hemodialysis patients tolerate fasting during dialysis. VLF evaluation may provide information that can be used to develop a more reasonable intradialytic nutritional supplementation method.

Auricular Acupressure in Relieving PONV and Promoting Gastrointestinal Function Recovery in Females After Laparoscopic Sleeve Gastrectomy: A Prospective Randomized Controlled Trial

BACKGROUND

The role of current pharmacological treatment after laparoscopic sleeve gastrectomy (LSG) is limited. The incidence of postoperative nausea and vomiting (PONV) after LSG remains high. Auricular acupressure (AA) is believed to relieve PONV after laparoscopic surgeries, but its role in patients with obesity after LSG has yet to be confirmed.

METHODS

Ninety-five female patients who underwent LSG were randomized into two groups: AA combined with conventional anti-nausea medication (AA group, 47 patients) or conventional anti-nausea medication group (control group, 48 patients). Index of nausea and vomiting and retching (INVR) scores, postoperative anti-vomiting medication use, time of first anus exhausting, time of first fluid intake, and time of first to get out of bed were collected within 48 h after surgery.

RESULTS

Demographic data of patients in both groups were balanced and comparable. INVR score (F = 7.505, P = 0.007), vomiting score (F = 11.903, P = 0.001), and retching score (F = 12.098, P = 0.001) were significantly lower in the AA group than that in the control group within 48 h postoperatively. Use of metoclopramide was significantly less in the AA group than in the control group (4.7 [5.5]) vs. 8.8 [7.6], P = 0.004); time to first anus exhausting was significantly less in the AA group than in the control group (17.50 [6.00] vs. 20.42 [8.62], P = 0.020).

CONCLUSIONS

AA combined with conventional anti-vomiting agents can alleviate PONV in female patients after LSG, and AA can promote gastrointestinal exhaustion.

TRIAL REGISTRATION

The trial has been registered in the Chinese Clinical Trial Registry (ChiCTR) with the registration no. ChiCTR2100047381 on June 13, 2021.

Dietary Fat Modulation of Gut Microbiota and Impact on Regulatory Pathways Controlling Food Intake

Obesity is a multifactorial disease that continues to increase in prevalence worldwide. Emerging evidence has shown that the development of obesity may be influenced by taxonomic shifts in gut microbiota in response to the consumption of dietary fats. Further, these alterations in gut microbiota have been shown to promote important changes in satiation signals including gut hormones (leptin, ghrelin, GLP-1, peptide YY and CCK) and orexigenic and anorexigenic neuropeptides (AgRP, NPY, POMC, CART) that influence hyperphagia and therefore obesity. In this review, we highlight mechanisms by which gut microbiota can influence these satiation signals both locally in the gastrointestinal tract and via microbiota-gut-brain communication. Then, we describe the effects of dietary interventions and associated changes in gut microbiota on satiety signals through microbiota-dependent mechanisms. Lastly, we present microbiota optimizing therapies including prebiotics, probiotics, synbiotics and weight loss surgery that can help restore beneficial gut microbiota by enhancing satiety signals to reduce hyperphagia and subsequent obesity. Overall, a better understanding of the mechanisms by which dietary fats induce taxonomical shifts in gut microbiota and their impact on satiation signaling pathways will help develop more targeted therapeutic interventions in delaying the onset of obesity and in furthering its treatment.

The Effects of Perioperative Probiotics on Postoperative Gastrointestinal Function in Patients with Brain Tumors: A Randomized, Placebo-Controlled Study

The incidence of postoperative gastrointestinal dysfunction among neurosurgical patients is as high as 80%. Probiotics help to maintain gastrointestinal barrier defense, provide competitive adherence to mucus and epithelial cells, and regulate gastrointestinal motility. Therefore, the purpose of this study was to investigate whether probiotics enhance gastrointestinal health after craniotomy in patients with brain tumors. This study was a 15-day, prospective, randomized, double-blind, placebo-controlled trial for patients being treated with elective craniotomy for brain tumors. Participants were randomly divided into the probiotics group (4 g probiotics, twice daily) and placebo group. The primary outcome was the time of first stool after surgery. The secondary outcomes included assessments of the gastrointestinal function, changes in gastrointestinal permeability and clinical outcomes. We enrolled a total of 200 participants (probiotics: 100; placebo: 100) and followed the principles of intention-to-treat analysis. The time of first stool and flatus were significantly shorter in the probiotics group compared to the placebo group (P < 0.001, respectively). No significant trends were observed for any other of the secondary outcome variables. Our findings suggest that probiotics can improve the gastrointestinal mobility of patients received craniotomy, and this improvement cannot be explained by changes in gastrointestinal permeability.

Perianaesthetic challenges in patients undergoing vagus nerve stimulation (VNS) placement

Patients with medically refractory epilepsy (MRE) are indicated for vagus nerve stimulation (VNS) placement. Anaesthesia for VNS placement is extremely challenging and requires several considerations. We present a man in his 20s with MRE who successfully underwent VNS placement. We review the mechanism of action of VNS, anaesthetic challenges and measures to prevent seizures.

Diet-microbial cross-talk underlying increased visceral perception

Visceral hypersensitivity, a fundamental mechanism of chronic visceral pain disorders, can result from both central or peripheral factors, or their combination. As an important regulator of normal gut function, the gut microbiota has been implicated as a key peripheral factor in the pathophysiology of visceral hypersensitivity. Patients with chronic gastrointestinal disorders, such as irritable bowel syndrome, often present with abdominal pain secondary to adverse reactions to dietary components. As both long- and short-term diets are major determinants of gut microbiota configuration that can result in changes in microbial metabolic output, it is becoming increasingly recognized that diet-microbiota interactions play an important role in the genesis of visceral sensitivity. Changes in pain signaling may occur via diet-induced changes in secretion of mediators by both the microbiota and/or host cells. This review will examine the peripheral influence of diet-microbiota interactions underlying increased visceral sensitivity.