Irritable bowel syndrome: a little understood organic bowel disease?

Familial coaggregation and shared familiality of functional and internalizing disorders in the Lifelines cohort

BACKGROUND

Functional disorders (FDs) are characterized by persistent somatic symptoms and are highly comorbid with internalizing disorders (IDs). To provide much-needed insight into FD etiology, we evaluated FD and ID familial coaggregation and shared familiality.

METHODS

Lifelines is a three-generation cohort study, which assessed three FDs (myalgic encephalomyelitis/chronic fatigue syndrome [ME/CFS], irritable bowel syndrome [IBS], and fibromyalgia [FM]) and six IDs (major depressive disorder [MDD], dysthymia [DYS], generalized anxiety disorder [GAD], agoraphobia [AGPH], social phobia [SPH], and panic disorder [PD]) according to diagnostic criteria. Based on 153,803 individuals, including 90,397 with a first-degree relative in Lifelines, we calculated recurrence risk ratios (λRs) and tetrachoric correlations to evaluate familial aggregation and coaggregation of these disorders in first-degree relatives. We then estimated their familiality and familial correlations.

RESULTS

Familial aggregation was observed across disorders, with λR ranging from 1.45 to 2.23 within disorders and from 1.17 to 1.94 across disorders. Familiality estimates ranged from 22% (95% confidence interval [CI]: 16-29) for IBS to 42% (95% CI: 33-50) for ME/CFS. Familial correlations ranged from +0.37 (95% CI: 0.24-0.51) between FM and AGPH to +0.97 (95% CI: 0.80-1) between ME/CFS and FM. The highest familial correlation between an ID and FD was +0.83 (95% CI: 0.66-0.99) for MDD and ME/CFS.

CONCLUSIONS

There is a clear familial component to FDs, which is partially shared with IDs. This suggests that IDs and FDs share both genetic and family-environmental risk factors. Of the FDs, ME/CFS is most closely related to IDs.

The Clinical Utility of Anorectal Manometry: A Review of Current Practices

Anorectal manometry (ARM) is a diagnostic test that utilizes pressure sensors to dynamically measure intraluminal anal and rectal pressures, thus providing an objective evaluation of anorectal functional parameters (tone, contractility, and relaxation), coordination and reflex activity, and sensation. ARM is a useful test for numerous indications including for the assessment and management of functional anorectal disorders such as fecal incontinence, functional defecatory disorders, and functional anorectal pain, preoperative assessment of anorectal function, and in facilitating/assessing response to biofeedback training. In addition, while many functional anorectal disorders present with overlapping symptoms (ie constipation, anorectal pain), ARM allows delineation of more specific disease processes and may guide treatment more effectively. In recent years the development of advanced manometric methodologies such as high-resolution anorectal manometry has also led to improved spatial resolution of data acquisition, further increasing the potential for the expansion of ARM. However, despite its ability to provide detailed information on anorectal and pelvic floor muscle function and synergy as well as the endorsements of several national and international organizations, ARM is still infrequently utilized in clinical practice. The purpose of this review is to address the current clinical applications and limitations of ARM for various disorders of the lower gastrointestinal tract. In so doing, we will provide clinicians with a framework for the use of ARM in clinical practice. This review will also discuss potential barriers to widespread adoption of ARM in clinical practice and propose possible solutions to these challenges.

Bacillus Subtilis (BG01-4TM) Improves Self-Reported Symptoms for Constipation, Indigestion, and Dyspepsia: A Phase 1/2A Randomized Controlled Trial

BACKGROUND

Functional gastrointestinal disorders (FGIDs) are common, difficult-to-manage conditions. Probiotics are emerging as a dietary component that influence gastrointestinal (GI) health. We conducted a double-blinded randomised controlled trial of a proprietary strain of deactivated Bacillus subtilis (BG01-4™) high in branched-chain fatty acids (BCFA) to treat self-reported FGID.

METHODS

Participants (n = 67) completed a four-week intervention of BG01-4™ (n = 34) or placebo (n = 33). The Gastrointestinal Symptom Rating Scale (GSRS) served as the outcome measure, collected prior to, at two weeks, and at four weeks after completion of the intervention.

RESULTS

At four weeks, one of three primary outcomes, constipation in the experimental group, was improved by 33% compared to placebo (15%); both other primary outcomes, Total GSRS and diarrhoea, were significantly improved in both the experimental and placebo groups (32%/26% and 20%/22%, respectively). The pre-planned secondary outcome, indigestion, was improved at four weeks (32%) but compared to the placebo (21%) was not significant (p = 0.079). Exploratory analysis, however, revealed that clusters for constipation (18% improvement, p < 0.001), indigestion (11% improvement, p = 0.04), and dyspepsia (10% improvement, p = 0.04) were significantly improved in the intervention group compared to the placebo.

CONCLUSIONS

These initial findings suggest that in people with self-reported FGID, BG01-4™ improves specific symptoms of constipation and related GI dysfunction. Longer-term confirmatory studies for this intervention are warranted.

TRIAL REGISTRATION

This study was registered prospectively (25 October 2021) at the Australian New Zealand Clinical Trials Registry (ACTRN12621001441808p).

Exploring the Nutrition Strategies Employed by Ultra-Endurance Athletes to Alleviate Exercise-Induced Gastrointestinal Symptoms-A Systematic Review

(1) Background: Participation in ultra-endurance sports, particularly ultra-running, has increased over the previous three decades. These are accompanied by high energetic demands, which may be further exacerbated by extreme environmental conditions. Preparation is long-term, comprising of sufficient exercise management, supportive dietary habits, and nutritional intakes for optimal adaptations. Gastrointestinal symptoms are often cited as causing underperformance and incompletion of events. Though the majority do not pose serious long-term health risks, they may still arise. It has been suggested that the nutritional interventions employed by such athletes prior to, during, and after exercise have the potential to alter symptom incidence, severity, and duration. A summary of such interventions does not yet exist, making it difficult for relevant personnel to develop recommendations that simultaneously improve athletic performance by attenuating gastrointestinal symptoms. The aim of this research is to systematically review the literature investigating the effects of a nutrition intervention on ultra-endurance athletes exercise-induced gastrointestinal symptom incidence, severity, or duration. (2) Methods: A systematic review of the literature was conducted (PubMed, CINAHL, Web of Science, and Sports Discus) in January 2023 to investigate the effects of various nutrition interventions on ultra-endurance athletes' (regardless of irritable bowel syndrome diagnosis) exercise-induced gastrointestinal symptoms. Variations of key words such as "ultra-endurance", "gastrointestinal", and "nutrition" were searched. The risk of bias in each paper was assessed using the ADA quality criteria checklist. (3) Results: Of the seven eligible studies, one was a single field-based case study, while the majority employed a crossover intervention design. A total of n = 105 participants (n = 50 male; n = 55 female) were included in this review. Practicing a diet low in short-chain, poorly absorbed carbohydrates, known as fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs), as well as employing repetitive gut challenges of carbohydrates, remain the most promising of strategies for exercise-induced gastrointestinal symptom management. (4) Conclusion: Avoiding high-FODMAP foods and practicing repetitive gut challenges are promising methods to manage gastrointestinal symptoms. However, sample sizes are often small and lack supportive power calculations.

The association between dietary acid load and odds and severity of irritable bowel syndrome in adults

No study has been conducted to investigate the association between dietary acid load and irritable bowel syndrome (IBS). So, this cross-sectional study was performed to investigate the association between dietary acid load and odds of IBS, its severity, and IBS subtypes. A sample of 3362 Iranian subjects was selected from health centers in Isfahan province. A validated semi-quantitative food frequency questionnaire (DS-FFQ) was applied to estimate dietary intakes. The dietary acid load was measured using net endogenous acid production (NEAP), dietary acid load (DAL), and potential renal acid load (PRAL) scores. In crude models, the highest compared with the lowest category of the PRAL score was significantly associated with increased odds of IBS severity in participants with BMI ≥ 25 (kg/m²) (OR = 1.54; 95% CI = (1.03-2.32). Also, the results indicated a significant positive association between the PARL and odds of mixed subtype of IBS (OR = 1.74; 95% CI = (1.11-2.74); P trend = 0.02). In propensity score-adjusted model with potential confounders, only a positive association was found between PRAL and odds of mixed subtype of IBS (OR = 1.78; 95% CI = (1.05-3.00); P trend = 0.03). The DAL and NEAP scores tended to show non-significant similar findings. This study indicates that dietary acid load might be associated with odds of mixed type of IBS. However, further research is warranted to infer these findings.

Children with chronic nausea and orthostatic intolerance have unique brain network organization: A case-control trial

BACKGROUND

Determine whether subjects with chronic nausea and orthostatic intolerance share common alterations in key brain networks associated with central autonomic control: default mode, salience, and central executive networks, and the insula, a key component of the salience network.

METHODS

Ten subjects (ages 12-18 years; 8 females, 2 males) with nausea predominant dyspepsia, orthostatic intolerance, and abnormal head-upright tilt test were consecutively recruited from pediatric gastroenterology clinic. These subjects were compared with healthy controls (n = 8) without GI symptoms or orthostatic intolerance. Resting-state fMRI and brain network modularity analyses were performed. Differences in the default mode, salience, and central executive networks, and insular connectivity were measured.

KEY RESULTS

The community structure of the default mode network and salience network was significantly different between tilt-abnormal children and controls (p = 0.034 and 0.012, respectively), whereas, no group difference was observed in the central executive network (p = 0.48). The default mode network was more consistently "intact," and the consistency of the community structure in the salience network was reduced in tilt-abnormal children, especially in the insula.

CONCLUSIONS AND INFERENCES

Children with chronic nausea and orthostatic intolerance have altered connectivity in the default mode network and salience network/insula, which supports over-monitoring of their body and altered processing of bodily states resulting in interoceptive hyper self-awareness. The connectivity of the salience network would not support optimal regulation of appropriate attention to internal and external stimuli, and the hyper-connected default mode network may result in a persistent self-referential state with feelings of emotion, pain, and anxiety.

Thalamic abnormalities in older adults with remitted early-onset depression using structural magnetic resonance imaging

BACKGROUND

The thalamus is a key diencephalic structure involved in major depressive disorder (MDD). Studies have consistently revealed abnormalities in thalamic volumes in older adults with late-onset depression (LOD), however abnormalities in older adults with early-onset depression (EOD) have not yet been well-studied.

METHODS

Fifty-nine euthymic participants with a history of EOD and fifty-nine matched comparison participants without a lifetime history of depression underwent neuroimaging, medical and neuropsychological assessments. Thalamic volumes were compared between groups. To investigate the previously-proposed right hemispheric (RH) dominance theory of MDD, we explored the bilateral, right and left hemispheric (LH) thalamic volumes. Multiple regression analyses were used to evaluate between-group and within-group effects. Correlational analyses examined associations between group and cognitive performance.

RESULTS

Relative to the comparison group, those with EOD had significantly larger bilateral, LH and RH thalamic volumes. Those with EOD, those who were younger, and those who had fewer years of education demonstrated larger bilateral and LH thalamic volumes. For RH thalamic volumes, those with EOD and those who were younger demonstrated larger RH thalamic volumes. EOD within-group models were also run to assess associations between relevant depression variables. The results showed that only age was significant for bilateral and RH thalamic volumes. For the LH thalamic volumes, the model was not significant. No significant correlations were found between cognitive performance and EOD groups.

CONCLUSION

Older adults with a history of EOD showed significantly larger bilateral, RH and LH thalamic volumes. Further research is needed to delineate potential underlying mechanisms of this change.

Stress Watch: The Use of Heart Rate and Heart Rate Variability to Detect Stress: A Pilot Study Using Smart Watch Wearables

Stress is an inherent part of the normal human experience. Although, for the most part, this stress response is advantageous, chronic, heightened, or inappropriate stress responses can have deleterious effects on the human body. It has been suggested that individuals who experience repeated or prolonged stress exhibit blunted biological stress responses when compared to the general population. Thus, when assessing whether a ubiquitous stress response exists, it is important to stratify based on resting levels in the absence of stress. Research has shown that stress that causes symptomatic responses requires early intervention in order to mitigate possible associated mental health decline and personal risks. Given this, real-time monitoring of stress may provide immediate biofeedback to the individual and allow for early self-intervention. This study aimed to determine if the change in heart rate variability could predict, in two different cohorts, the quality of response to acute stress when exposed to an acute stressor and, in turn, contribute to the development of a physiological algorithm for stress which could be utilized in future smartwatch technologies. This study also aimed to assess whether baseline stress levels may affect the changes seen in heart rate variability at baseline and following stress tasks. A total of 30 student doctor participants and 30 participants from the general population were recruited for the study. The Trier Stress Test was utilized to induce stress, with resting and stress phase ECGs recorded, as well as inter-second heart rate (recorded using a FitBit). Although the present study failed to identify ubiquitous patterns of HRV and HR changes during stress, it did identify novel changes in these parameters between resting and stress states. This study has shown that the utilization of HRV as a measure of stress should be calculated with consideration of resting (baseline) anxiety and stress states in order to ensure an accurate measure of the effects of additive acute stress.

Uncovering the pathophysiology of irritable bowel syndrome by exploring the gut-brain axis: a narrative review

Objective

To improve the pathophysiological understanding of irritable bowel syndrome (IBS) by exploring the gut-brain axis.

Background

Disorders of gut-brain interaction (DGBIs) are gastrointestinal (GI) disorders in which alterations in bowel functions occur. IBS, which is one of the most studied DGBIs, is linked with abdominal distress or pain without obvious structural or biochemical anomalies.

Methods

The etiology of IBS has not been clearly described but is known to be multifactorial, involving GI motility changes, post-infectious reactivity, visceral hypersensitivity, gut-brain interactions, microbiota dysbiosis, small intestinal bacterial overgrowth, food sensitivity, carbohydrate malabsorption, and intestinal inflammation.

Conclusions

One of the main features of IBS is the occurrence of structural and functional disruptions in the gut-brain axis, which alter reflective and perceptual nervous system reactions. Herein, we provide a brief summary of this topic. Furthermore, we discuss animal models, which are important in the study of IBS, especially as it is linked with stressors. These animal models cannot fully represent the human disease but serve as important tools for understanding this complicated disorder. In the future, technologies, such as organ-on-a-chip models and metabolomics, will provide novel information regarding the pathophysiology of IBS, which will play an important role in treatment development. Finally, we take a brief glance at how acupuncture treatments may hold potential for patients with IBS.

Pharmacological treatments of Chinese herbal medicine for irritable bowel syndrome in adults: A network meta-analysis of randomized controlled trials

INTRODUCTION

Plenty of clinical studies have suggested the value of Chinese herbal medicine (CHM) for patients with irritable bowel syndrome (IBS), but their efficacy and safety have not been systematically concluded yet. This article aimed to compare and rank the therapeutic effect and safety of CHM with routine pharmacotherapies and placebo in the treatment of IBS.

METHODS

Randomized controlled trials regarding CHM to treat IBS were searched in six databases from inception to Jan 31, 2020. A network meta-analysis was conducted to analyze the data of included publications. The quality assessment was assessed by Cochrane Handbook and GRADEpro software. The risk ratio was calculated for dichotomous outcomes while the standardized mean difference was used for continuous variables with 95% credible intervals. A Funnel plot was performed to evaluate publication bias. The surface under the cumulative ranking curve was conducted to rank the included interventions. Data were analyzed with STATA 15.0 and Review Manager 5.3.

RESULT

3194 records were searched, and 28 eligible trials involving 3323 patients ere identified. Compared with conventional therapies and placebo, Jianpi-Chushi therapy showed significant improvement in adequate relief and IBS symptom severity scale; Shugan-Jianpi therapy showed the best efficacy in relieving the abdominal pain and abdominal distension; Wenshen-Jianpi therapy had a better effect on avoiding adverse effects and improving stool character.

CONCLUSION

This study confirmed that CHM could be beneficial for patients with IBS in relieving their clinical symptoms and should be recommended as alternative therapies. The quality of evidence in this study based on the GRADE system was "low".

The effects of tegaserod, a gastrokinetic agent, on voltage-gated K+ channels in rabbit coronary arterial smooth muscle cells

Tegaserod, a gastroprokinetic agent, is used to treat irritable bowel syndrome. Despite its extensive clinical use, little is known about the effects of tegaserod on vascular ion channels, especially K+ channels. Therefore, we examined the effects of tegaserod on voltage-gated K+ (Kv) channels in rabbit coronary arterial smooth muscle cells using the whole-cell patch-clamp technique. Tegaserod inhibited Kv channels in a concentration-dependent manner with an IC50 value of 1.26 ± 0.31 µmol/L and Hill coefficient of 0.81 ± 0.10. Although tegaserod had no effect on the steady-state activation curves of the Kv channels, the steady-state inactivation curve was shifted toward a more negative potential. These results suggest that tegaserod inhibits Kv channels by influencing their voltage sensors. The recovery time constant of channel inactivation was extended in the presence of tegaserod. Furthermore, application of train steps (1 and 2 Hz) in the presence of tegaserod progressively increased the inhibition of Kv currents suggesting that tegaserod-induced Kv channel inhibition is use (state)-dependent. Pretreatment with a Kv1.5 subtype inhibitor suppressed the Kv current. However, additional application of tegaserod did not induce further inhibition. Pretreatment with a Kv2.1 or Kv7 inhibitor did not affect the inhibitory effect of tegaserod on Kv channels. Based on these results, we conclude that tegaserod inhibits vascular Kv channels in a concentration- and use (state)-dependent manner independent of its own functions. Furthermore, the major Kv channel target of tegaserod is the Kv1.5 subtype.

Fatigue in irritable bowel syndrome is associated with plasma levels of TNF-α and mesocorticolimbic connectivity

Irritable bowel syndrome (IBS) is a symptom-based disorder of gut-brain interactions generating abdominal pain. It is also associated with a vulnerability to develop extraintestinal symptoms, with fatigue often reported as one of the most disturbing. Fatigue is related to brain function and inflammation in several disorders, however, the mechanisms of such relations in IBS remain elusive. This study aimed to elucidate fatigue and its association with a resting state network of mesocorticolimbic regions of known importance in fatigue, and to explore the possible role of circulating TNF-α levels in IBS and healthy controls (HC). Resting state functional magnetic resonance imaging (fMRI) was conducted in 88 IBS patients and 47 HC of similar age and gender to investigate functional connectivity between mesocorticolimbic regions. Further, fatigue impact on daily life and plasma levels of the proinflammatory cytokine tumor necrosis factor-α (TNF-α), of known relevance to immune activation in IBS, were also measured. The selected mesocorticolimbic regions indeed formed a functionally connected network in all participants. The nucleus accumbens (NAc), in particular, exhibited functional connectivity to all other regions of interest. In IBS, fatigue impact on daily life was negatively correlated with the connectivity between NAc and dorsolateral prefrontal cortex bilaterally (left p = 0.019; right p = 0.038, corrected for multiple comparisons), while in HC, fatigue impact on daily life was positively correlated to the connectivity between the right NAc and anterior middle insula in both hemispheres (left p = 0.009; right p = 0.011). We found significantly higher levels of TNF-α in IBS patients compared to HC (p = 0.001) as well as a positive correlation between TNF-α and fatigue impact on daily life in IBS patients (rho = 0.25, p = 0.02) but not in HC (rho = -0.13, p = 0.37). There was no association between functional connectivity in the mesocorticolimbic network and plasma levels of TNF-α in either group In summary, this novel multimodal study provides the first evidence that the vulnerability to fatigue in IBS is associated with connectivity within a mesocorticolimbic network as well as immune activation. These findings warrant further investigation, both peripherally and potentially with measurements of central immune activation as well.

TMT proteomics analysis of intestinal tissue from patients of irritable bowel syndrome with diarrhea: Implications for multiple nutrient ingestion abnormality

Diarrheal irritable bowel syndrome (IBS-D) is a chronic functional bowel disease with no clear diagnostic markers and no satisfactory treatment strategies. In recent years, the importance of intestinal microstructure and function in IBS-D has been emphasized. However, the intestinal tissue proteomics of IBS-D patients has not been analyzed. Here, we systematically analyzed the molecule profiling of the intestinal tissues in IBS-D patients through tandem mass tag (TMT)-based proteomics for the first time, aiming to reveal the pathogenesis and provide evidence for diagnosis and treatment of IBS-D. Five IBS-D patients and five healthy subjects were selected, biopsy tissue samples from the junction of sigmoid and rectum were analyzed by TMT proteomics. Differentially expressed proteins were obtained and bioinformatics analysis was performed. Furthermore, parallel reaction monitoring (PRM) and q-PCR detection were applied to validate the differentially expressed proteins. Eighty differentially expressed proteins were screened, 48 of which were up-regulated and 32 were down-regulated (fold change >1.2, P < 0.05). Bioinformatics analysis showed that these proteins were significantly enriched in the nutrient ingestion pathways which are related to immune molecules. SELENBP1, VSIG2, HMGB1, DHCR7, BCAP31 and other molecules were significantly changed. Our study revealed the underlying mechanisms of IBS-D intestinal dysfunction. SIGNIFICANCE: Irritable bowel syndrome with diarrhea (IBS-D) is a worldwide chronic intestinal disease with no definite diagnostic markers. It is still a challenge to accurately locate the pathogenesis of patients for appropriate treatment strategy. Established proteomics studies of IBS-D are only based on urine, blood, or tissue samples from animals. Our study was the first TMT proteomics analysis on intestinal biopsy tissues of patients with IBS-D, which revealed the changes of molecular spectrum of actual intestinal conditions in patients with IBS-D. Some important molecules and signaling pathways have been found abnormal in our study, which were related with nutrient uptake. They not only provided preliminary clues for low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) intolerance, an unsolved conundrum of IBS-D, but also revealed obscure problems of protein, lipid, and other nutrients ingestion in IBS-D patients. Some of these differentially expressed molecules have been preliminarily verified, and will may be potential candidate molecules for diagnostic markers of IBS-D.

Disease, Drugs and Dysbiosis: Understanding Microbial Signatures in Metabolic Disease and Medical Interventions

Since the discovery of the potential role for the gut microbiota in health and disease, many studies have gone on to report its impact in various pathologies. These studies have fuelled interest in the microbiome as a potential new target for treating disease Here, we reviewed the key metabolic diseases, obesity, type 2 diabetes and atherosclerosis and the role of the microbiome in their pathogenesis. In particular, we will discuss disease associated microbial dysbiosis; the shift in the microbiome caused by medical interventions and the altered metabolite levels between diseases and interventions. The microbial dysbiosis seen was compared between diseases including Crohn’s disease and ulcerative colitis, non-alcoholic fatty liver disease, liver cirrhosis and neurodegenerative diseases, Alzheimer’s and Parkinson’s. This review highlights the commonalities and differences in dysbiosis of the gut between diseases, along with metabolite levels in metabolic disease vs. the levels reported after an intervention. We identify the need for further analysis using systems biology approaches and discuss the potential need for treatments to consider their impact on the microbiome.

How Serotonin Level Fluctuation Affects the Effectiveness of Treatment in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is one of the most commonly diagnosed functional gastrointestinal (GI) disorders. It affects both men and women. Enteric serotonin (5HT) is responsible for gut motility, secretion, visceral hypersensitivity, and inflammation. The serotonin reuptake transporter (SERT) maintains serotonin levels by regulating its reuptake. An increase in SERT expression causes a decrease in serotonin, which leads to IBS-C (irritable bowel syndrome, constipation-predominant), whereas a decrease in SERT transcription causes an increase in serotonin, which leads to IBS-D (irritable bowel syndrome, diarrhea-predominant). Some factors can alter SERT transcription, such as certain bacteria, inflammation, growth factor, and glucagon-like peptide-1. This shows that 5HT and SERT both have an important role in IBS pathophysiology so that it would be a better subject to target for the treatment aspect of IBS. 5HT3 receptor antagonists are advisable for IBS-D to block the excessive activity of serotonin at the 5HT3 receptor and reduce gut motility. For IBS-C, we prescribe 5HT4 receptor agonists, which promote gut motility. Also, the latest treatment approach, antidepressant drugs TCAs (tricyclic antidepressants) and SSRIs (selective serotonin reuptake inhibitors), are helpful by modulating serotonin levels in the gut. In this literature review, we found that serotonin is one of the main pathophysiological factors for IBS, and we can treat IBS by targeting serotonin function on gut motility.

Is There a Correlation Between Irritable Bowel Syndrome and Lactose Intolerance?

Irritable bowel syndrome (IBS) is a poorly understood gastrointestinal disorder that affects a significant percentage of the population and has a strong negative effect on the quality of life. The lack of known pathophysiologic mechanisms has made finding effective treatment strategies difficult. One of the common recommendations by clinicians is a trial of a lactose-free diet. We have wondered if there was sufficient evidence in the currently available literature to support such a recommendation. We have also looked into other possible relationships between malabsorption syndromes and IBS. All the articles used for this review have been found in the PubMed database. We have taken into consideration the possibility that there may be both genetic differences and differences in the gut microbiome between populations living in different geographic regions. Therefore, we have included articles from different geographic regions to increase the generalizability of the findings. While there is a plethora of evidence that IBS patients commonly report milk intolerance, we have not found any conclusive evidence to suggest an objective link between IBS and any known malabsorption syndromes, including lactose malabsorption. Furthermore, trials of lactase supplementation have not led to clinical benefit. We concluded that there was no evidence to support routinely recommending a lactose-free diet for patients diagnosed with IBS, but including hydrogen breath testing in routine workup of IBS is a reasonable clinical decision. Ultimately, we believe that more clinical trials and chemical studies of the feces are needed to determine the pathophysiology and explore possible dietary recommendations for patients with IBS.

Primary healthcare utilisation and self-rated health among patients with Irritable Bowel Syndrome: What are the impacts of comorbidities, gastrointestinal symptom burden, sense of coherence and stress?

OBJECTIVES

Irritable Bowel Syndrome (IBS) is a chronic gastrointestinal disease associated with impaired quality of life and an increased use of healthcare services. Self-ratings of health have proven a powerful predictor of health outcomes. The aim of this study was to evaluate the unique impacts of comorbidities, gastrointestinal symptoms, perceived stress and sense of coherence on the number of healthcare contacts and self-rated health of IBS patients in Swedish primary care.

METHODS

In this cross-sectional study, 186 primary-care IBS patients and 360 non-IBS patients (as a reference group) were administrated a test battery of validated questionnaires. Data on comorbidities and healthcare-seeking frequency were obtained from a registry.

RESULTS

In the reduced multivariable logistic regression model, average days of abdominal pain/week (OR = 0.83, 95% CI = 0.72-0.96), age (OR = 0.95, 95% CI = 0.92-0.97) and sense of coherence (OR = 1.07, 95% CI = 1.03-1.11) remained independent, statistically significant predictors of IBS (and non-IBS) patients reporting good health. Only the number of comorbidities in general (OR = 1.22, 95% CI = 1.14-1.32) and sleep disorders in particular (OR = 5.40, 95% CI = 1.85-15.76) independently predicted high levels of primary healthcare utilisation among IBS patients.

CONCLUSION

Lack of gastrointestinal symptoms, a high sense of coherence and younger age were associated with better self-rated health in both IBS and non-IBS patients. The number of comorbidities in general and sleep disorders in particular were associated with frequent PHC contacts in IBS patients. The association between frequent primary-care contacts and sleep disorders was not seen in the control group, indicating a unique association with IBS patients.

Comparison of comorbid depression between irritable bowel syndrome and inflammatory bowel disease: A meta-analysis of comparative studies

BACKGROUND

The prevalence of comorbid depression is high in chronic gastrointestinal disorders, including irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). For these two disorders in particular, the findings have not been consistent. This meta-analysis systematically compares the rates and severity of comorbid depression between IBS and IBD patients.

METHODS

A systematic literature search was conducted using PubMed, PsycINFO, Embase, Cochrane Library, Wan Fang, SinoMed, Chinese National Knowledge Infrastructure from their inception date to September 12, 2017 for comparative studies on IBS and IBD patients. Standardized mean differences (SMDs) and odds ratios (OR) of comorbid depression were calculated using random effect models. Data on comorbid anxiety in the included studies were also extracted and analyzed.

RESULTS

Altogether, 22 studies with 1,244 IBS and 1,048 IBD patients were included. While there was no significant group difference in the prevalence of depression (10 studies, OR = 1.18, 95%CI: 0.87-1.60, P = 0.29), the IBS group had more severe depression (pooled SMD = 0.18, 95%CI: 0.04-0.33, P = 0.01) and anxiety than the IBD group (pooled SMD = 0.31, 95%CI: 0.14-0.49, P = 0.0006). Sixteen (72.7%) studies were assessed as 'high quality' using the Newcastle-Ottawa Scale (NOS).

CONCLUSIONS

Although the prevalence of comorbid depression was similar between groups, IBS patients had more severe comorbid depressive and anxiety symptoms compared to IBD patients. Appropriate assessment and treatment of depressive and anxiety symptoms in these patient groups should be implemented.

Association of mitochondrial displacement loop polymorphisms with diarrhea-predominant irritable bowel syndrome: A preliminary study

OBJECTIVES

To investigate whether single nucleotide polymorphisms (SNPs) in the mitochondrial displacement loop (D-loop) were associated with irritable bowel syndrome (IBS).

METHODS

Altogether 40 participants were recruited and classified into three groups, including 20 that fulfilled the Rome III criteria for diarrhea-predominant IBS (IBS-D), 10 with constipation-predominant IBS (IBS-C), and 10 healthy volunteers (controls). DNA was extracted from biopsy specimens of the colon obtained during routine colonoscopies. The mitochondrial D-loop was sequenced and variants were identified in comparison with the reference sequence from GenBank. We searched GenBank and MITOMAP to determine whether a variant could be considered an SNP.

RESULTS

No significant differences in sex, age and body mass index were found among the three groups. The average numbers of SNPs in the IBS-D, IBS-C and control groups were 12.2 ± 2.7, 9.8 ± 1.8 and 9.9 ± 2.1, respectively. The frequency of SNPs was significantly higher in the IBS-D group than in the IBS-C group and controls (P < 0.05). No significant difference was found between the latter two groups. Each SNP was compared among the three groups and the frequency of 199C was found to be significantly higher in the control group than in the IBS-D group (P = 0.03), but no significant difference in its frequency was found between the IBS-C group and controls.

CONCLUSIONS

Patients with IBS-D have a higher incidence of SNPs in the mitochondrial D-loop than controls. The genotype 199C may be associated with a lower risk of IBS-D.

Clinical Practice Guidelines for Irritable Bowel Syndrome in Korea, 2017 Revised Edition

In 2011, the Korean Society of Neurogastroenterology and Motility (KSNM) published clinical practice guidelines on the management of irritable bowel syndrome (IBS) based on a systematic review of the literature. The KSNM planned to update the clinical practice guidelines to support primary physicians, reduce the socioeconomic burden of IBS, and reflect advances in the pathophysiology and management of IBS. The present revised version of the guidelines is in continuity with the previous version and targets adults diagnosed with, or suspected to have, IBS. A librarian created a literature search query, and a systematic review was conducted to identify candidate guidelines. Feasible documents were verified based on predetermined inclusion and exclusion criteria. The candidate seed guidelines were fully evaluated by the Guidelines Development Committee using the Appraisal of Guidelines for Research and Evaluation II quality assessment tool. After selecting 7 seed guidelines, the committee prepared evidence summaries to generate data exaction tables. These summaries comprised the 4 main themes of this version of the guidelines: colonoscopy; a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols; probiotics; and rifaximin. To adopt the core recommendations of the guidelines, the Delphi technique (ie, a panel of experts on IBS) was used. To enhance dissemination of the clinical practice guidelines, a Korean version will be made available, and a food calendar for patients with IBS is produced.

Beneficial effects of Rifaximin in post-infectious irritable bowel syndrome mouse model beyond gut microbiota

BACKGROUND AND AIMS

Rifaximin is a minimally absorbed antibiotic, which has shown efficacy in irritable bowel syndrome (IBS) patients. However, the mechanism on how it effects in IBS is still incompletely defined. In this study, Trichinella spiralis-infected post-infectious (PI) IBS mouse model was used, to assess the action of rifaximin on visceral hypersensitivity, barrier function, gut inflammation, and microbiota.

METHODS

Post-infectious IBS model was established by T. spiralis infection in mice. Rifaximin were administered to PI-IBS mice for seven consecutive days. The abdominal withdrawal reflex and threshold of colorectal distention were employed to evaluate visceral sensitivity. Smooth muscle contractile response was recorded in the organ bath. Intestinal permeability was measured by Ussing chamber. Expression of tight junction protein and cytokines were measured by Western blotting. Ilumina miseq platform was used to analyze bacterial 16S ribosomal RNA.

RESULTS

Post-infectious IBS mice treated with rifaximin exhibited decreased abdominal withdrawal reflex score, increased threshold, reduced contractile response, and intestinal permeability. Rifaximin also suppressed the expression of interleukin-12 and interleukin-17 and promoted the expression of the major tight junction protein occludin. Furthermore, rifaximin did not change the composition and diversity, and the study reavealed that rifaximin had a tiny effect on the relative abundance of Lactobacillus and Bifidobacterium in this PI-IBS model.

CONCLUSIONS

Rifaximin alleviated visceral hypersensitivity, recovered intestinal barrier function, and inhibited low-grade inflammation in colon and ileum of PI-IBS mouse model. Moreover, rifaximin exerts anti-inflammatory effects with only a minimal effect on the overall composition and diversity of the gut microbiota in this model.

Sexual Abuse Is Associated With an Abnormal Psychological Profile and Sleep Difficulty in Patients With Irritable Bowel Syndrome in Taiwan

Background/Aims

Both sexual and physical abuse history have been reported to be associated with irritable bowel syndrome (IBS) in Western countries. The impact of abuse history in IBS patients in Asia remains unclear. We aim to determine the prevalence of abuse history, its associated psychological profiles, and sleep problems among IBS patients in Taiwan.

Methods

In total, 194 Rome III-defined IBS patients were invited to participate. Age- and sex-matched healthy carriers of chronic hepatitis B or hepatitis C without chronic abdominal symptoms were identified as disease-controls. We administered a validated questionnaire to evaluate bowel symptoms, physical/sexual abuse history, anxiety/depression (Hospital Anxiety and Depression Scale [HADS]), and sleep quality.

Results

IBS patients had a significantly higher prevalence of sexual abuse history than the disease-control group both before (16.5% vs 6.7%, P < 0.05) and after (16.0% vs 6.6%, P < 0.05) adolescence. These significant differences were mainly observed in women (13.4% vs 3.4%, P < 0.05). No difference was noted in history of physical abuse between the 2 groups. IBS patients with a history of sexual abuse had significantly higher HADS scores and higher frequencies of sleep difficulty than those without.

Conclusions

In Taiwan, sexual abuse history was more prevalent in female IBS patients than controls. Sexual abuse history may contribute to higher anxiety/depression levels and sleep difficulties, which are commonly experienced in IBS patients. In Asia, abuse history should be obtained when approaching IBS patients to facilitate better management.

Gene expression profiles in peripheral blood mononuclear cells correlate with salience network activity in chronic visceral pain: A pilot study

BACKGROUND

Distinct gene expression profiles in peripheral blood mononuclear cells (PBMCs) consistent with increased sympathetic nervous system activity have been described in different populations under chronic stress. Neuroinflammatory brain changes, possibly related to the migration of primed monocytes to the brain, have been implicated in the pathophysiology of chronic pain. Irritable bowel syndrome (IBS) is a stress-sensitive gastrointestinal disorder associated with altered brain-gut interactions and increased sympathetic/vagal tone and anxiety. Reports about immune alterations in IBS are conflicting. This pilot study aimed to test how PBMC gene expression inflammatory profiles are correlated with altered brain signatures in the salience system.

METHODS

Sixteen IBS and 16 healthy controls (HCs) completed resting state MRI scans. Gene expression profiles in PBMCs were assessed using human transcriptome array-2. Bioinformatic analyses determined differential expression of PBMCs between IBS and HCs. Partial least squares, a multivariate analysis technique, was used to identify disease correlations between PBMC gene expression profiles and functional activity in the brain's salience network.

KEY RESULTS

Regions of the salience network, including the mid cingulate cortex, and mid and superior temporal gyrus were positively correlated with several pro-inflammatory genes (interleukin 6, APOL2) in IBS, but negatively correlated with several anti-inflammatory genes (KRT8, APOA4) in HCs.

CONCLUSIONS & INFERENCES

Based on rodent studies, one may speculate that chronically activated stress signaling pathways in IBS maintain a pro-inflammatory state in the periphery. Alternatively, primed monocytes may migrate to the brain during stress, inducing regional neuroinflammatory changes in salience regions involved in the modulation of visceral sensitivity.

Relationship between use of selective serotonin reuptake inhibitors and irritable bowel syndrome: A population-based cohort study

AIM

To investigate the relationship between selective serotonin reuptake inhibitor (SSRI) use and the subsequent development of irritable bowel syndrome (IBS).

METHODS

This retrospective, observational, population-based cohort study collected data from Taiwan's National Health Insurance Research Database. A total of 19653 patients newly using SSRIs and 78612 patients not using SSRIs, matched by age and sex at a ratio of 1:4, were enrolled in the study from January 1, 2000 to December 31, 2010. The patients were followed until IBS diagnosis, withdrawal from the National Health Insurance system, or the end of 2011. We analyzed the effects of SSRIs on the risk of subsequent IBS using Cox proportional hazards regression models.

RESULTS

A total of 236 patients in the SSRI cohort (incidence, 2.17/1000 person-years) and 478 patients in the comparison cohort (incidence, 1.04/1000 person-years) received a new diagnosis of IBS. The mean follow-up period from SSRI exposure to IBS diagnosis was 2.05 years. The incidence of IBS increased with advancing age. Patients with anxiety disorders had a significantly increased adjusted hazard ratio (aHR) of IBS (aHR = 1.33, 95%CI: 1.11-1.59, P = 0.002). After adjusting for sex, age, urbanization, family income, area of residence, occupation, the use of anti-psychotics and other comorbidities, the overall aHR in the SSRI cohort compared with that in the comparison cohort was 1.74 (95%CI: 1.44-2.10; P < 0.001). The cumulative incidence of IBS was higher in the SSRI cohort than in the non-SSRI cohort (log-rank test, P < 0.001).

CONCLUSION

SSRI users show an increased risk of subsequent diagnosis of IBS in Taiwan.

Do Symptoms of Irritable Bowel Syndrome Improve when Patients Receive Cognitive Behavioural Therapy for Co-morbid Anxiety Disorders in a Primary Care Psychological Therapy (IAPT) Service?

BACKGROUND

Irritable bowel syndrome (IBS) is a common co-morbid condition with anxiety disorders, and patients often report a fear of incontinence in public places. This type of bowel control anxiety (BCA) can be conceptualized as a phobic syndrome. Yet little evidence exists on the prevalence or outcomes of these co-morbidities in routine primary care psychological therapy (Improving Access to Psychological Therapies, IAPT) services.

AIMS

To examine the prevalence and outcomes of IBS and BCA patients treated with cognitive behavioural therapy (CBT) for anxiety disorders within a routine IAPT service.

METHOD

An observational cohort study screened 2322 referrals to an IAPT service over 12 months for the presence of IBS. Patients with co-morbid anxiety disorders and IBS were grouped into those with, and without BCA. Patients completed the IBS symptom severity scale and the IAPT minimum data set. Diagnoses and outcomes were examined for all groups up to 6 months follow-up.

RESULTS

A greater proportion of BCA patients had a primary diagnosis of phobic disorder. After receiving CBT, patients made clinically significant improvement in both anxiety and IBS symptoms at 6 months follow-up. Patients with BCA made greater improvement in phobia scales and IBS symptoms than non-BCA patients.

CONCLUSIONS

Anxiety disorders with co-morbid IBS improved significantly in a routine IAPT service. A significant proportion of co-morbid IBS sufferers had a fear of incontinence in public places (BCA). Directly addressing and modifying these fears with CBT appeared to enhance improvement in both phobic anxiety and IBS symptoms.

The mucosal immune system: master regulator of bidirectional gut-brain communications

Communication between the brain and gut is not one-way, but a bidirectional highway whereby reciprocal signals between the two organ systems are exchanged to coordinate function. The messengers of this complex dialogue include neural, metabolic, endocrine and immune mediators responsive to diverse environmental cues, including nutrients and components of the intestinal microbiota (microbiota-gut-brain axis). We are now starting to understand how perturbation of these systems affects transition between health and disease. The pathological repercussions of disordered gut-brain dialogue are probably especially pertinent in functional gastrointestinal diseases, including IBS and functional dyspepsia. New insights into these pathways might lead to novel treatment strategies in these common gastrointestinal diseases. In this Review, we consider the role of the immune system as the gatekeeper and master regulator of brain-gut and gut-brain communications. Although adaptive immunity (T cells in particular) participates in this process, there is an emerging role for cells of the innate immune compartment (including innate lymphoid cells and cells of the mononuclear phagocyte system). We will also consider how these key immune cells interact with the specific components of the enteric and central nervous systems, and rapidly respond to environmental variables, including the microbiota, to alter gut homeostasis.

Cortisol levels in hair are altered in irritable bowel syndrome - A case control study in primary care

OBJECTIVE

Stress is an important component in the pathophysiology of irritable bowel syndrome (IBS). Long term Hypothalamus Pituitary Adrenal (HPA)-axis activity can be studied by measuring hair cortisol concentrations (HCC). Some previous studies have indicated a dysregulated HPA-axis in IBS patients, but cortisol levels in hair have not yet been studied. We investigated whether HCC and self-reported stress differentiate IBS patients from controls.

METHODS

In a cross-sectional study within 10 Swedish Primary Health Care Centers we compared patients in working age with active IBS to patients without GI complaints. The participants donated hair samples and completed questionnaires including a scale of self-reported perceived stress (PSS). 169 Rome III-fulfilling IBS patients and 316 non-IBS patients were available for final analyses.

RESULTS

IBS patients had significantly lower HCC, median=16.3pg/mg, IQR=26.9pg/mg, compared to non-IBS patients, median=22.8pg/mg, IQR=29.1pg/mg. There was also a difference in the distribution of HCC quintiles between the two groups, with 30.2% IBS patients and 14.2% of non-IBS patients in the lowest quintile of HCC. PSS was higher among IBS patients with a mean (SD) total score of 25.3 (8.0) compared to controls 21.4, (7.5). Quintiles of HCC and PSS stayed significantly but very weakly related to IBS (B=-0.332, Std error=0.146, p<0.005) in multivariable analyses.

CONCLUSION

This study suggests a possible suppression of the HPA-axis activity in a considerable portion of IBS patients.

Lipopolysaccharide induces visceral hypersensitivity: role of interleukin-1, interleukin-6, and peripheral corticotropin-releasing factor in rats

BACKGROUND

Lipopolysaccharide (LPS) induces visceral hypersensitivity, and corticotropin-releasing factor (CRF) also modulates visceral sensation. Besides, LPS increases CRF immunoreactivity in rat colon, which raises the possibility of the existence of a link between LPS and the CRF system in modulating visceral sensation. The present study tried to clarify this possibility.

METHODS

Visceral sensation was assessed by abdominal muscle contractions induced by colonic balloon distention, i.e., visceromotor response, electrophysiologically in conscious rats. The threshold of visceromotor response was measured before and after administration of drugs.

RESULTS

LPS at a dose of 1 mg/kg subcutaneously (sc) decreased the threshold at 3 h after the administration. Intraperitoneal (ip) administration of anakinra (20 mg/kg), an interleukin-1 (IL-1) receptor antagonist, or interleukin-6 (IL-6) antibody (16.6 µg/kg) blocked this effect. Additionally, IL-1β (10 µg/kg, sc) or IL-6 (10 µg/kg, sc) induced visceral allodynia. Astressin (200 µg/kg, ip), a non-selective CRF receptor antagonist, abolished the effect of LPS, but astressin₂-B (200 µg/kg, ip), a CRF receptor type 2 (CRF2) antagonist, did not alter it. Peripheral CRF receptor type 1 (CRF1) stimulation by cortagine (60 µg/kg, ip) exaggerated the effect of LPS, but activation of CRF2 by urocortin 2 (60 µg/kg, ip) abolished it.

CONCLUSIONS

LPS induced visceral allodynia possibly through stimulating IL-1 and IL-6 release. In addition, this effect was mediated through peripheral CRF signaling. Since the LPS-cytokine system is thought to contribute to altered visceral sensation in the patients with irritable bowel syndrome, these results may further suggest that CRF plays a crucial role in the pathophysiology of this disease.

Potential of in vivo real-time gastric gas profiling: a pilot evaluation of heat-stress and modulating dietary cinnamon effect in an animal model

Gastroenterologists are still unable to differentiate between some of the most ordinary disorders of the gut and consequently patients are misdiagnosed. We have developed a swallowable gas sensor capsule for addressing this. The gases of the gut are the by-product of the fermentation processes during digestion, affected by the gut state and can consequently provide the needed information regarding the health of the gut. Here we present the first study on gas sensor capsules for revealing the effect of a medical supplement in an animal (pig) model. We characterise the real-time alterations of gastric-gas in response to environmental heat-stress and dietary cinnamon and use the gas profiles for understanding the bio-physiological changes. Under no heat-stress, feeding increases gastric CO2 concentration, while dietary cinnamon reduces it due to decrease in gastric acid and pepsin secretion. Alternatively, heat-stress leads to hyperventilation in pigs, which reduces CO2 concentration and with the cinnamon treatment, CO2 diminishes even more, resulting in health improvement outcomes. Overall, a good repeatability in gas profiles is also observed. The model demonstrates the strong potential of real-time gas profiler in providing new physiological information that will impact understanding of therapeutics, presenting a highly reliable device for monitoring/diagnostics of gastrointestinal disorders.

Immune response in irritable bowel syndrome: A systematic review of systemic and mucosal inflammatory mediators

OBJECTIVE

To systematically review the available data on cytokine and immune cells in the peripheral blood and mucosal biopsy samples from patients with irritable bowel syndrome (IBS).

METHODS

From a review of the literature, data on cytokines and immune cells that had been assayed in at least three independent studies were collated and trends examined.

RESULTS

Levels of interleukin (IL)-10 tended to be decreased and those of IL-6, IL-8, tumor necrosis factor-α and IL-1β increased in the systemic circulation in IBS, while in the mucosa, IL-10 was decreased and IL-8, mast cells, enterochromaffin cells and CD3⁺ T lymphocytes were increased. However, these findings were not consistent across all studies and, in some instances, were limited to certain IBS sub-populations.

CONCLUSIONS

The interpretation of this literature is limited by several factors, such as the intrinsic heterogeneity of IBS and a lack of standardization in study design. While a number of intriguing immunological observations have been made in IBS, more work is needed before a compelling case can be made for a role for immune-mediated events in the etiology of IBS.

Effectiveness of osteopathic manipulative therapy for managing symptoms of irritable bowel syndrome: a systematic review

CONTEXT

Irritable bowel syndrome (IBS) is a common and often lifelong functional gastrointestinal disorder. There is a scarcity of effective management options for IBS.

OBJECTIVE

To assess the effectiveness of osteopathic manipulative therapy (OMTh) for managing the symptoms of IBS.

DATA SOURCES

Articles without language or publication-date restriction were searched in PubMed, Embase, Cochrane Library, PEDro, OSTMED.DR, and Osteopathic Research Web. Search terms included irritable bowel syndrome, IBS, functional colonic disease, colon irritable, osteopath*, osteopathic manipulation, osteopathic medicine, clinical trial, and randomized clinical trial. Experts in the field of visceral osteopathy were also contacted to identify additional studies.

STUDY SELECTION

The authors evaluated randomized controlled trials (RCTs) of OMTh for IBS in adults in whom IBS was diagnosed using Rome (I-III) criteria. If OMTh was not the sole intervention in the intervention group and if the same additional interventions were not applied to the control group, the study was excluded.

DATA EXTRACTION

Citation identification, study selection, and data extraction were independently undertaken by 2 reviewers with a data extraction form from the Cochrane Collaboration. A consensus method was used to resolve disagreements concerning the assessment of the methodologic quality of the RCTs that were reviewed.

RESULTS

The search identified 10 studies that examined OMTh for patients with IBS; 5 studies (204 patients) met the inclusion criteria. All studies were assessed as having low risk of bias according to the Cochrane Collaboration criteria, although there was heterogeneity in the outcome measures and control interventions. Three studies used visual analog scales for abdominal pain, whereas others used the IBS severity score and the Functional Bowel Disorder Severity Index. A variety of secondary outcomes were used. All studies reported more pronounced short-term improvements with OMTh compared with sham therapy or standard care only. These differences remained statistically significant after variable lengths of follow-up in 3 studies.

CONCLUSION

The present systematic review provides preliminary evidence that OMTh may be beneficial in the treatment of patients with IBS. However, caution is required in the interpretation of these findings because of the limited number of studies available and the small sample sizes.

Visceral Hypersensitivity and Altered Colonic Motility in Type 2 Diabetic Rat

Background/Aims

Abnormal visceral sensitivity and disordered motility are common in patients with diabetes mellitus. The purpose of the present study was to investigate whether visceral sensation and bowel motility were altered in a rat model of type 2 diabetes mellitus accompanied by weight loss.

Methods

A type 2 diabetic rat model in adulthood was developed by administrating streptozotocin (STZ; 90 mg/kg, i.p.) to neonatal rats. Eight weeks after STZ administration, rats with blood glucose level of 200 mg/dL or higher were selected and used as diabetic group (n = 35) in this study. Abdominal withdrawal reflex and arterial pulse rate were measured to examine visceral nociception induced by colorectal distension (0.1–1.0 mL). The amplitude, frequency, and area under the curve (AUC) of spontaneous phasic contractions of colonic circular muscles were recorded in vitro to examine colonic motility.

Results

STZ-treated diabetic rats gained significantly less weight for 8 weeks than control (P < 0.01). Forty-eight percent of the diabetic rats showed enhanced visceral nociceptive response to colorectal distension. Diabetic rats did not differ from control rats in colorectal compliance. However, the frequency and AUC, not the amplitude, of colonic spontaneous contraction in vitro was significantly decreased in diabetic rats compared to control rats (P < 0.01 in frequency and P < 0.05 in AUC).

Conclusions

These results demonstrate visceral hypersensitivity and colonic dysmotility in a rat model of type 2 diabetes mellitus accompanied by weight loss.

More negative self-esteem and inferior coping strategies among patients diagnosed with IBS compared with patients without IBS--a case-control study in primary care

Background

Irritable Bowel Syndrome (IBS) is a chronic, relapsing gastrointestinal disorder, that affects approximately 10% of the general population and the majority are diagnosed in primary care. IBS has been reported to be associated with altered psychological and cognitive functioning such as mood disturbances, somatization, catastrophizing or altered visceral interoception by negative emotions and stress. The aim was to investigate the psychosocial constructs of self-esteem and sense of coherence among IBS patients compared to non-IBS patients in primary care.

Methods

A case–control study in primary care setting among IBS patients meeting the ROME III criteria (n = 140) compared to controls i.e. non-IBS patients (n = 213) without any present or previous gastrointestinal complaints. The data were collected through self-reported questionnaires of psychosocial factors.

Results

IBS-patients reported significantly more negative self-esteem (p < 0.001), lower scores for positive self-esteem (p < 0.001), and lower sense of coherence (p < 0.001) than the controls. The IBS-cases were also less likely to report ‘good’ health status (p < 0.001) and less likely to report a positive belief in the future (p < 0.001). After controlling for relevant confounding factors in multiple regressions, the elevation in negative self-esteem among IBS patients remained statistically significant (p = 0.02), as did the lower scores for sense of coherence among IBS cases (p = 0.04).

Conclusions

The more frequently reported negative self-esteem and inferior coping strategies among IBS patients found in this study suggest the possibility that psychological therapies might be helpful for these patients. However these data do not indicate the causal direction of the observed associations. More research is therefore warranted to determine whether these psychosocial constructs are more frequent in IBS patients.

Irritable bowel syndrome: A microbiome-gut-brain axis disorder?

Irritable bowel syndrome (IBS) is an extremely prevalent but poorly understood gastrointestinal disorder. Consequently, there are no clear diagnostic markers to help diagnose the disorder and treatment options are limited to management of the symptoms. The concept of a dysregulated gut-brain axis has been adopted as a suitable model for the disorder. The gut microbiome may play an important role in the onset and exacerbation of symptoms in the disorder and has been extensively studied in this context. Although a causal role cannot yet be inferred from the clinical studies which have attempted to characterise the gut microbiota in IBS, they do confirm alterations in both community stability and diversity. Moreover, it has been reliably demonstrated that manipulation of the microbiota can influence the key symptoms, including abdominal pain and bowel habit, and other prominent features of IBS. A variety of strategies have been taken to study these interactions, including probiotics, antibiotics, faecal transplantations and the use of germ-free animals. There are clear mechanisms through which the microbiota can produce these effects, both humoral and neural. Taken together, these findings firmly establish the microbiota as a critical node in the gut-brain axis and one which is amenable to therapeutic interventions.

Epidermal growth factor upregulates serotonin transporter and its association with visceral hypersensitivity in irritable bowel syndrome

AIM: To investigate the role of epidermal growth factor (EGF) in visceral hypersensitivity and its effect on the serotonin transporter (SERT).

METHODS: A rat model for visceral hypersensitivity was established by intra-colonic infusion of 0.5% acetic acid in 10-d-old Sprague-Dawley rats. The visceral sensitivity was assessed by observing the abdominal withdrawal reflex and recording electromyographic activity of the external oblique muscle in response to colorectal distension. An enzyme-linked immunosorbent assay was used to measure the EGF levels in plasma and colonic tissues. SERT mRNA expression was detected by real-time PCR while protein level was determined by Western blot. The correlation between EGF and SERT levels in colon tissues was analyzed by Pearson’s correlation analysis. SERT function was examined by tritiated serotonin (5-HT) uptake experiments. Rat intestinal epithelial cells (IEC-6) were used to examine the EGF regulatory effect on SERT expression and function via the EGF receptor (EGFR).

RESULTS: EGF levels were significantly lower in the rats with visceral hypersensitivity as measured in plasma (2.639 ± 0.107 ng/mL vs 4.066 ± 0.573 ng/mL, P < 0.01) and in colonic tissue (3.244 ± 0.135 ng/100 mg vs 3.582 ± 0.197 ng/100 mg colon tissue, P < 0.01) compared with controls. Moreover, the EGF levels were positively correlated with SERT levels (r = 0.820, P < 0.01). EGF displayed dose- and time-dependent increased SERT gene expressions in IEC-6 cells. An EGFR kinase inhibitor inhibited the effect of EGF on SERT gene upregulation. SERT activity was enhanced following treatment with EGF (592.908 ± 31.515 fmol/min per milligram vs 316.789 ± 85.652 fmol/min per milligram protein, P < 0.05) and blocked by the EGFR kinase inhibitor in IEC-6 cells (590.274 ± 25.954 fmol/min per milligram vs 367.834 ± 120.307 fmol/min per milligram protein, P < 0.05).

CONCLUSION: A decrease in EGF levels may contribute to the formation of visceral hypersensitivity through downregulation of SERT-mediated 5-HT uptake into enterocytes.

Treatment of diarrhea-predominant irritable bowel syndrome with mesalazine and/or Saccharomyces boulardii

CONTEXT

Irritable bowel syndrome (IBS) is a functional bowel disease characterized by abdominal pain and altered intestinal habits. The pathophysiology of IBS remains unclear. Recent studies have demonstrated that some IBS patients, especially in diarrhea-predominant IBS (IBS-D), display persistent signs of minor mucosal inflammation and a modified intestinal microflora. The mesalazine has known intestinal anti-inflammatory properties. Saccharomyces boulardii is a probiotic used for a long time in treatment of diarrhea, including infectious diarrhea.

OBJECTIVE

Evaluate the effects of mesalazine alone, combined therapy of mesalazine with liophylised Saccharomyces boulardii or alone on symptoms of IBS-D patients.

METHODS

Based on Rome III criteria, 53 IBS-D patients (18 year or more) were included. To exclude organic diseases all patients underwent colonoscopy, stool culture, serum anti-endomisium antibody, lactose tolerance test and ova and parasite exam. Patients were divided in three groups: mesalazine group (MG) - 20 patients received mesalazine 800 mg t.i.d. for 30 days; mesalazine and Saccharomyces boulardii group (MSbG) - 21 patients received mesalazine 800 mg t.i.d. and Saccharomyces boulardii 200 mg t.i.d. for 30 days and; Saccharomyces boulardii group (SbG) - 12 patients received Sb 200 mg t.i.d. for 30 days. Drugs that might have any effect on intestinal motility or secretion were not allowed. Symptom evaluations at baseline and after treatment were performed by means of a 4-point likert scale including: stool frequency, stool form and consistency (Bristol scale), abdominal pain and distension. Paired t test and Kruskal-Wallis test were used for statistical analyses.

RESULTS

Compared to baseline, there were statistically significant reduction of symptom score after 30 th day therapy in all three groups: MG (P<0.0001); MSbG (P<0.0001) and in SbG (P = 0.003). There were statistically significant differences in the symptom score at 30 th day therapy of the MG, MSbG and SbG groups (P = 0.03). There were no statistical differences between MSbG and MG symptom score at 30th day therapy (P = 0.9).

CONCLUSIONS

The use of mesalazine alone, Saccharomyces boulardii alone or combined treatment with mesalasine and Saccaromyces boulardii improved IBS-D symptoms. The improvement of the symptom score was greater with mesalazine alone or combined with Sb as compared with Sb treatment alone. These preliminary results suggest that mezalazine may be useful in treatment of IBS-d patients, and warrant further larger studies.

Role of negative affects in pathophysiology and clinical expression of irritable bowel syndrome

Irritable bowel syndrome (IBS) is regarded as a multifactorial disease in which alterations in the brain-gut axis signaling play a major role. The biopsychosocial model applied to the understanding of IBS pathophysiology assumes that psychosocial factors, interacting with peripheral/central neuroendocrine and immune changes, may induce symptoms of IBS, modulate symptom severity, influence illness experience and quality of life, and affect outcome. The present review focuses on the role of negative affects, including depression, anxiety, and anger, on pathogenesis and clinical expression of IBS. The potential role of the autonomic nervous system, stress-hormone system, and immune system in the pathophysiology of both negative affects and IBS are taken into account. Psychiatric comorbidity and subclinical variations in levels of depression, anxiety, and anger are further discussed in relation to the main pathophysiological and symptomatic correlates of IBS, such as sensorimotor functions, gut microbiota, inflammation/immunity, and symptom reporting.

Irritable bowel syndrome: pathogenesis, diagnosis, treatment, and evidence-based medicine

Irritable bowel syndrome (IBS) is a chronic and debilitating functional gastrointestinal disorder that affects 9%-23% of the population across the world. The percentage of patients seeking health care related to IBS approaches 12% in primary care practices and is by far the largest subgroup seen in gastroenterology clinics. It has been well documented that these patients exhibit a poorer quality of life and utilize the health care system to a greater degree than patients without this diagnosis. The pathophysiology of IBS is not clear. Many theories have been put forward, but the exact cause of IBS is still uncertain. According to the updated ROME III criteria, IBS is a clinical diagnosis and presents as one of the three predominant subtypes: (1) IBS with constipation (IBS-C); (2) IBS with diarrhea (IBS-D); and (3) mixed IBS (IBS-M); former ROME definitions refer to IBS-M as alternating IBS (IBS-A). Across the IBS subtypes, the presentation of symptoms may vary among patients and change over time. Patients report the most distressing symptoms to be abdominal pain, straining, myalgias, urgency, bloating and feelings of serious illness. The complexity and diversity of IBS presentation makes treatment difficult. Although there are reviews and guidelines for treating IBS, they focus on the efficacy of medications for IBS symptoms using high-priority endpoints, leaving those of lower priority largely unreported. Therefore, the aim of this review is to provide a comprehensive evidence-based review of the diagnosis, pathogenesis and treatment to guide clinicians diagnosing and treating their patients.

Early life factors initiate a 'vicious circle' of affective and gastrointestinal symptoms: A longitudinal study

OBJECTIVE

Functional gastrointestinal disorders (FGID) have been shown to be associated with both comorbid mood disorders and traumatic events such as abuse earlier in life. In a longitudinal study, we tested a model that hypothesized: (i) childhood abuse was associated with subsequent mood disorder and pain or interference in life by bowel symptoms both directly and indirectly via neurotic personality; and (ii) an ongoing cycle of mood disorder impacts on bowel symptoms.

DESIGN

Subjects from the general population classified as irritable bowel syndrome and/or functional dyspepsia (IBS/FD, n = 207) or free of FGID (n = 100) were prospectively studied every 6 months over 18 months. In addition to bowel symptom interference and abdominal pain, measures of personality (neuroticism), childhood abuse history, depression, and anxiety were obtained. The hypothesized model was tested via Path Modelling.

RESULTS

Childhood abuse was found to be directly associated with neuroticism but only indirectly associated with baseline interference and mood disorders (via neuroticism). The data further supported an ongoing cycle of elevations in mood disorders and pain/interference by bowel symptoms. The data supported direct effects of interference at one time point on interference at the subsequent time point in addition to indirect effects of prior anxiety and depression. Repeating the model with pain frequency as the outcome yielded almost identical findings which suggests the findings are generalized across domains of symptoms and quality-of-life.

CONCLUSION

Our data provide support for a model characterized by a 'vicious circle' between mood disorders and FGID symptoms in adulthood, with initial input from early life factors.

Irritable bowel syndrome: Emerging paradigm in pathophysiology

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders, characterized by abdominal pain, bloating, and changes in bowel habits. These symptoms cannot be explained by structural abnormalities and there is no specific laboratory test or biomarker for IBS. Therefore, IBS is classified as a functional disorder with diagnosis dependent on the history taking about manifested symptoms and careful physical examination. Although a great deal of research has been carried out in this area, the pathophysiology of IBS is complex and not completely understood. Multiple factors are thought to contribute to the symptoms in IBS patients; altered gastrointestinal motility, visceral hypersensitivity, and the brain-gut interaction are important classical concepts in IBS pathophysiology. New areas of research in this arena include inflammation, postinfectious low-grade inflammation, genetic and immunologic factors, an altered microbiota, dietary factors, and enteroendocrine cells. These emerging studies have not shown consistent results, provoking controversy in the IBS field. However, certain lines of evidence suggest that these mechanisms are important at least a subset of IBS patients, confirming that IBS symptoms cannot be explained by a single etiological mechanism. Therefore, it is important to keep in mind that IBS requires a more holistic approach to determining effective treatment and understanding the underlying mechanisms.

A biomarker panel and psychological morbidity differentiates the irritable bowel syndrome from health and provides novel pathophysiological leads

BACKGROUNDS

The development of a reliable biomarker for irritable bowel syndrome (IBS) remains one of the major aims of research in functional gastrointestinal disorders (FGIDs) and is complicated by the absence of a perfect reference standard. Previous efforts based on genetic and immune markers have showed promise, but have not been robust.

AIM

To evaluate an extensive panel of gene expression and serology markers combined with psychological measures in differentiating IBS from health and between subtypes of IBS.

METHODS

Of subjects eligible for analysis (N = 244), 168 met criteria for IBS (60 IBS-C, 57 IBS-D and 51 mixed), while 76 were free of any FGID. A total of 34 markers were selected based on pathways implicated in pathophysiology of IBS or whole human genome screening. Psychological measures were recorded that covered anxiety, depression and somatisation. Models differentiating disease and health were based on unconditional logistic regression and performance assessed through area under the receiver-operator characteristic curve (AUC), sensitivity and specificity.

RESULTS

The performance of a combination of 34 markers was good in differentiating IBS from health (AUC = 0.81) and was improved considerably with the addition of four psychological markers (combined AUC = 0.93). Of the 34 markers considered, discrimination was derived largely from a small subset. Good discrimination was also obtained between IBS subtypes with the best being observed for IBS-C vs. IBS-D (AUC = 0.92); however, psychological variables provided almost no incremental discrimination subtypes over biological markers (combined AUC = 0.94).

CONCLUSIONS

A combination of gene expression and serological markers in combination with psychological measures shows exciting progress towards a diagnostic test for IBS compared with healthy subjects, and to discriminate IBS-C from IBS-D.

Effect of probiotic bacteria on the intestinal microbiota in irritable bowel syndrome

BACKGROUND AND AIM

In irritable bowel syndrome (IBS), the gut microbiota may be altered. Probiotic bacteria appear to be therapeutically effective. We characterized the mucosa-associated microbiota, and determined the clinical and microbiological effects of orally administered probiotic bacteria, in patients with IBS.

METHODS

Mucosal microbiota from rectal biopsies of IBS patients and controls were assessed on the V1 and V2 variable regions of the 16S ribosomal RNA gene amplified using 454 pyrosequencing. Clinical symptoms and changes in mucosal microbiota were assessed in IBS patients before and after 4 weeks of treatment with probiotic mix VSL#3.

RESULTS

Ten IBS subjects (eight female; mean age 46 years) were included. At week 4 of probiotic therapy, six patients showed symptom improvement on global symptom assessment compared with baseline (P = 0.031). Before therapy, intestinal microbiota of IBS subjects differed significantly from that of healthy controls, with less diversity and evenness than controls (n = 9; P < 0.05), increased abundance of Bacteroidetes (P = 0.014) and Synegitestes (P = 0.017), and reduced abundance of Actinobacteria (P = 0.004). The classes Flavobacteria (P = 0.028) and Epsilonproteobacteria (P = 0.017) were less enriched in IBS. Abundance differences were largely consistent from the phylum to genus level. Probiotic treatment in IBS patients was associated with a significant reduction of the genus Bacteroides (all taxonomy levels; P < 0.05) to levels similar to that of controls.

CONCLUSION

In this pilot study, global and deep molecular analysis demonstrates an altered mucosal microbiota composition in IBS. Probiotic leads to detectable changes in the microbiota. These effects of probiotic bacteria may contribute to their therapeutic benefit.

Patients with irritable bowel syndrome are more burdened by co-morbidity and worry about serious diseases than healthy controls--eight years follow-up of IBS patients in primary care

Background

Irritable Bowel Syndrome (IBS) is a hidden public health disease that affects up to 20% of the general population. Although co-morbidity can affect diagnose setting and treatment of the disease, there are few studies concerning diagnosed and registered co-morbidity for IBS patients in primary care. The aim of this study was to analyse co-morbidity among IBS-patients compared to age- and sex-matched controls from the general population using data from a county-wide computerized medical record system.

Methods

IBS cases were recruited from three Swedish primary health care centres during a five-years period and controls from the same corresponding geographical areas. Co-morbidity data for IBS-patients and morbidity data for controls were derived from a population-based Health Care Register (HCR) covering all diagnoses in primary as well as hospital care in the region. Odds Ratios with 95% confidence intervals for morbidity in gastro-intestinal and non-gastrointestinal diagnoses for cases with irritable bowel syndrome compared to controls were calculated separately for each gender and diagnosis.

Results

We identified more co-morbidity among IBS patients of both sexes, compared to matched controls in the general population. Patients with IBS were particularly more worried about having a serious disease than their control group. The risk among male IBS-cases to get this latter diagnose was three times higher compared to the male controls.

Conclusions

In this population based case–control study, the analysis of diagnoses from the HCR revealed a broad spectrum of common co-morbidity and significantly more physician-recorded diagnoses among IBS-patients in comparisons to the control group.

Irritable bowel syndrome and migraine: bystanders or partners?

Irritable bowel syndrome (IBS) and migraine are distinct clinical disorders. Apart from the characteristics of chronic and recurrent pain in nature, these pain-related disorders apparently share many similarities. For example, IBS is female predominant with community prevalence about 5-10%, whereas that of migraine is 1-3% also showing female predominance. They are often associated with many somatic and psychiatric comorbidities in terms of fibromyaglia, chronic fatigue syndrome, interstitial cystitis, insomnia and depression etc., even the IBS subjects may have coexisted migraine with an estimated odds ratio of 2.66. They similarly reduce the quality of life of victims leading to the social, medical and economic burdens. Their pathogeneses have been somewhat addressed in relation to biopsychosocial dysfunction, heredity, genetic polymorphism, central/visceral hypersensitivity, somatic/cutaneous allodynia, neurolimbic pain network, gonadal hormones and abuses etc. Both disorders are diagnosed according to the symptomatically based criteria. Multidisciplinary managements such as receptor target new drugs, melantonin, antispasmodics, and psychological drugs and measures, complementary and alternatives etc. are recommended to treat them although the used agents may not be necessarily the same. Finally, the prognosis of IBS is pretty good, whereas that of migraine is less fair since suicide attempt and stroke are at risk. In conclusion, both distinct chronic pain disorders to share many similarities among various aspects probably suggest that they may locate within the same spectrum of a pain-centered disorder such as central sensitization syndromes. The true pathogenesis to involve these disorders remains to be clarified in the future.

IgG-based elimination diet in migraine plus irritable bowel syndrome

OBJECTIVES

To evaluate therapeutic potential of the immunoglobulin G (IgG)-based elimination diet among migraine patients with irritable bowel syndrome (IBS).

BACKGROUND

Food elimination has been suggested as an effective and inexpensive therapeutic strategy in patients with migraine and concomitant IBS in the past studies.

METHODS

A total of 21 patients (mean [standard deviation] age: 38.0 [11.2] years; 85.7% females) diagnosed with migraine and IBS were included in this double-blind, randomized, controlled, cross-over clinical trial composed of baseline (usual diet), first diet (elimination or provocation diets), and second diet (interchange of elimination or provocations diets) phases and 4 visits.

RESULTS

IgG antibody tests against 270 food allergens revealed mean (standard deviation) reaction count to be 23.1 (14.1). Compared with baseline levels, elimination diet per se was associated with significant reductions in attack count (4.8 [2.1] vs 2.7 [2.0]; P < .001), maximum attack duration (2.6 [0.6] vs. 1.4 [1.1] days; P < .001), mean attack duration (1.8 [0.5] vs. 1.1 [0.8] days; P < .01), maximum attack severity (visual analog scale 8.5 [1.4] vs. visual analog scale 6.6 [3.3]; P < .001), and number of attacks with acute medication (4.0 [1.5] vs. 1.9 [1.8]; P < .001). There was a significant reduction in pain-bloating severity (1.8 [1.3] vs. 3.2 [0.8]; P < .05), pain-bloating within the last 10 days (3.2 [2.8] vs. 5.5 [3.1]; P < .05), and improvement obtained in quality of life (3.6 [1.4] vs. 2.9 [1.0]; P < .05) by the elimination diet as compared with provocation diet.

CONCLUSIONS

Our findings indicate that food elimination based on IgG antibodies in migraine patients who suffer from concomitant IBS may effectively reduce symptoms from both disorders with possible positive impact on the quality of life of the patients as well as potential savings to the health-care system.

Food patch testing for irritable bowel syndrome

BACKGROUND

The traditional classification of irritable bowel syndrome (IBS) as a functional disorder has been challenged in recent years by evidence of ongoing low-grade gastrointestinal tract inflammation. Inflammation may alter gastrointestinal motility and thus be central to the pathogenesis of IBS. Many foods and food additives are known to cause allergic contact dermatitis. We hypothesize that allergenic foods and food additives may elicit a similar allergic reaction in the gastrointestinal tract, giving rise to symptoms suggestive of IBS.

OBJECTIVE

We sought to determine whether skin patch testing to a panel of foods and food additives may identify food allergens that may be responsible for symptoms of IBS.

METHODS

We performed skin patch testing to common allergenic foods and food additives on individuals with a history of or symptoms suggestive of IBS. We used patch test-guided avoidance diets to determine whether avoidance alleviates IBS symptoms.

RESULTS

Thirty of the 51 study participants showed at least 1 doubtful or positive patch test result. Fourteen of the participants reported symptomatic improvement, ranging from slight to great, upon avoidance of the foods/food additives to which they reacted.

LIMITATIONS

Double-blind study design, inclusion of only patients with active IBS, larger sample size, more balanced gender distribution, testing of more foods/food additives, and longer duration of and more precise quantification of response to dietary avoidance are suggested for future studies.

CONCLUSION

Allergic contact enteritis to ingested foods, food additives, or both may contribute to IBS symptoms. Patch testing may be useful in identifying the causative foods.

Efficacy and safety of selective serotonin reuptake inhibitor antidepressants in patients with irritable bowel syndrome: A systematic review

AIM: To systematically assess the efficacy and safety of selective serotonin reuptake inhibitor (SSRI) antidepressants (SSRIs) for irritable bowel syndrome (IBS).

METHODS: PubMed, Embase, the Cochrane Central Register of Controlled Trials, Chinese Biomedical Literature Database, and China Journal Full-text Database were searched for randomized controlled trials investigating the efficacy of SSRIs in the management of IBS. The Revman 5.0 software provided by the Cochrane Collaboration was used for assessment.

RESULTS: Five placebo-controlled, double-blind, randomized trials including 300 patients were involved in this analysis. SSRIs used in these studies included citalopram, fluoxetine and paroxetine. Compared to placebo, SSRIs were not associated with a statistically significant global symptom relief [RR = 2.09, 95%CI = (0.97, 4.47), P < 0.05]. There was no significant difference in the incidence of serious adverse events between the SSRIs and placebo groups[RR = 1.38, 95%CI = (0.68, 2.82), P > 0.05].

CONCLUSION: There are no significant differences in IBS symptom improvement and incidence of side effects between SSRI and placebo groups.

Effect of the 5-HT4 receptor and serotonin transporter on visceral hypersensitivity in rats

Visceral hypersensitivity plays an important role in motor and sensory abnormalities associated with irritable bowel syndrome, but the underlying mechanisms are not fully understood. The present study was designed to evaluate the expression of the 5-HT₄ receptor and the serotonin transporter (SERT) as well as their roles in chronic visceral hypersensitivity using a rat model. Neonatal male Sprague-Dawley rats received intracolonic injections of 0.5% acetic acid (0.3-0.5 mL at different times) between postnatal days 8 and 21 to establish an animal model of visceral hypersensitivity. On day 43, the threshold intensity for a visually identifiable contraction of the abdominal wall and body arching were recorded during rectal distention. Histological evaluation and the myeloperoxidase activity assay were performed to determine the severity of inflammation. The 5-HT₄ receptor and SERT expression of the ascending colon were monitored using immunohistochemistry and Western blot analyses; the plasma 5-HT levels were measured using an ELISA method. As expected, transient colonic irritation at the neonatal stage led to visceral hypersensitivity, but no mucosal inflammation was later detected during adulthood. Using this model, we found reduced SERT expression (0.298 ± 0.038 vs 0.634 ± 0.200, P < 0.05) and increased 5-HT₄ receptor expression (0.308 ± 0.017 vs 0.298 ± 0.021, P < 0.05). Treatment with fluoxetine (10 mg·kg⁻¹·day⁻¹, days 36-42), tegaserod (1 mg·kg⁻¹·day⁻¹, day 43), or the combination of both, reduced visceral hypersensitivity and plasma 5-HT levels. Fluoxetine treatment increased 5-HT₄ receptor expression (0.322 ± 0.020 vs 0.308 ± 0.017, P < 0.01) but not SERT expression (0.219 ± 0.039 vs 0.298 ± 0.038, P = 0.654). These results indicate that both the 5-HT₄ receptor and SERT play a role in the pathogenesis of visceral hypersensitivity, and its mechanism may be involved in the local 5-HT level.