Irritable bowel syndrome patients show enhanced modulation of visceral perception by auditory stress

Novel insights in the role of peripheral corticotropin-releasing factor and mast cells in stress-induced visceral hypersensitivity

Visceral hypersensitivity is one of the hallmarks in irritable bowel syndrome (IBS) pathophysiology. Stress is well known to affect visceral sensitivity in humans and rodents, an effect which is associated in part with alterations of intestinal epithelial permeability in rodents. Although the pathophysiology of visceral hypersensitivity is still unclear, two key factors have been identified as playing a major role in its modulation, namely peripheral corticotropin-releasing factor (CRF) and mast cells. In a recent study in Neurogastroenterology and Motility, van den Wijngaard et al. demonstrate that the mast-cell dependent visceral hypersensitivity observed in maternally separated rats after an acute exposure to a psychological stress can be prevented but not reversed by the peripherally restricted CRF receptor antagonist, α-helical CRF(9-41). They further show that the preventive effect of the CRF receptor antagonist is linked to a stabilization of mast cells and maintenance of the epithelial barrier at the colonic level. These data suggest that post stress mast cell activation and subsequent visceral hypersensitivity are not targeted by peripheral CRF receptor antagonists. These novel insights in the role of peripheral CRF in the modulation of stress-induced visceral hypersensitivity add to our growing understanding of the mechanisms that may lie at the origin of visceral pain disturbances following stress and will contribute to enhance the development of drugs that may have potential therapeutic benefits for IBS patients.

Altered psychobiological responsiveness in women with irritable bowel syndrome

OBJECTIVE

Although stress has been considered an important pathophysiological factor in irritable bowel syndrome (IBS), there is incomplete understanding of its physiological mechanisms. The current study was designed to compare diurnal hypothalamic-pituitary-adrenal (HPA) axis activity in IBS patients and controls and their psychobiological response to a psychosocial stressor.

METHODS

Basal and stimulated HPA axis activity was assessed in 57 women with IBS and 20 matched controls. Psychiatric comorbidity was assessed using a standardized clinical interview. Salivary morning cortisol and diurnal profile were obtained, and the Trier Social Stress Test (TSST) was administered. Levels of cortisol and adrenocorticotropic hormone (ACTH) were measured before and within 1 hour after the stressor. Overall stress experience and stress related to the TSST were assessed using standardized questionnaires.

RESULTS

All subjects showed intact circadian variation of cortisol. However, IBS patients with predominant diarrhea exhibited substantially heightened cortisol levels at awakening (p < .03) and a blunted cortisol awakening response. In response to the TSST, patients exhibited significantly blunted cortisol (p < .05) and slightly attenuated ACTH secretion compared with controls. During the recovery period, ACTH levels were significantly lower (p < .04) in patients than those in healthy subjects. Women with IBS perceived higher stress susceptibility than control subjects did (p < .01).

CONCLUSIONS

The enhanced morning cortisol levels in one subgroup of IBS patients may indicate an association between basal HPA axis activity and predominant bowel habit. The downregulated HPA axis reactivity in IBS after the TSST suggests a downregulated sensitivity of the endocrine system. On the contrary, all subjective stress ratings were increased in the IBS group, which may indicate increased stress susceptibility.

Stress-induced visceral analgesia assessed non-invasively in rats is enhanced by prebiotic diet

AIM

To investigate the influence of repeated water avoidance stress (rWAS) on the visceromotor response (VMR) to colorectal distension (CRD) and the modulation of the response by a prebiotic diet in rats using a novel surgery-free method of solid-state manometry.

METHODS

Male Wistar rats fed a standard diet with or without 4% enzyme-treated rice fiber (ERF) for 5 wk were subjected to rWAS (1 h daily x 10 d) or no stress. The VMR to graded phasic CRD was assessed by intraluminal colonic pressure recording on days 0 (baseline), 1 and 10 (45 min) and 11 (24 h) after rWAS and expressed as percentage change from baseline. Cecal content of short chain fatty acids and distal colonic histology were assessed on day 11.

RESULTS

WAS on day 1 reduced the VMR to CRD at 40 and 60 mmHg similarly by 28.9% ± 6.6% in both diet groups. On day 10, rWAS-induced reduction of VMR occurred only at 40 mmHg in the standard diet group (36.2% ± 17.8%) while in the ERF group VMR was lowered at 20, 40 and 60 mmHg by 64.9% ± 20.9%, 49.3% ± 11.6% and 38.9% ± 7.3% respectively. The visceral analgesia was still observed on day 11 in ERF- but not in standard diet-fed rats. By contrast the non-stressed groups (standard or ERF diet) exhibited no changes in VMR to CRD. In standard diet-fed rats, rWAS induced mild colonic histological changes that were absent in ERF-fed rats exposed to stress compared to non-stressed rats. The reduction of cecal content of isobutyrate and total butyrate, but not butyrate alone, was correlated with lower visceral pain response. Additionally, ERF diet increased rWAS-induced defecation by 26% and 75% during the first 0-15 min and last 15-60 min, respectively, compared to standard diet, and reduced rats' body weight gain by 1.3 fold independently of their stress status.

CONCLUSION

These data provide the first evidence of psychological stress-related visceral analgesia in rats that was enhanced by chronic intake of ERF prebiotic.

Psychological Co-morbidity in Functional Gastrointestinal Disorders: Epidemiology, Mechanisms and Management

Functional gastrointestinal disorder (FGID) is one of the commonest digestive diseases worldwide and leads to significant morbidity and burden on healthcare resource. The putative bio-psycho-social pathophysiological model for FGID underscores the importance of psychological distress in the pathogenesis of FGID. Concomitant psychological disorders, notably anxiety and depressive disorders, are strongly associated with FGID and these psychological co-morbidities correlate with severity of FGID symptoms. Early life adversity such as sexual and physical abuse is more commonly reported in patients with FGID. There is mounting evidence showing that psychological disorders are commonly associated with abnormal central processing of visceral noxious stimuli. The possible causal link between psychological disorders and FGID involves functional abnormalities in various components of the brain-gut axis, which include hypothalamic-pituitary-adrenal system, sympathetic and parasympathetic nervous system, serotonergic and endocannabinoid systems. Moreover, recent studies have also shown that psychological distress may alter the systemic and gut immunity, which is increasingly recognized as a pathophysiologic feature of FGID. Psychotropic agent, in particular antidepressant, and psychological intervention such as cognitive behavioral therapy and meditation have been reported to be effective for alleviation of gastrointestinal symptoms and quality of life in FGID patients. Further studies are needed to evaluate the impact of early detection and management of co-morbid psychological disorders on the long-term clinical outcome and disease course of FGID.

Chronic psychosocial stress induces reversible mitochondrial damage and corticotropin-releasing factor receptor type-1 upregulation in the rat intestine and IBS-like gut dysfunction

The association between psychological and environmental stress with functional gastrointestinal disorders, especially irritable bowel syndrome (IBS), is well established. However, the underlying pathogenic mechanisms remain unknown. We aimed to probe chronic psychosocial stress as a primary inducer of intestinal dysfunction and investigate corticotropin-releasing factor (CRF) signaling and mitochondrial damage as key contributors to the stress-mediated effects. Wistar-Kyoto rats were submitted to crowding stress (CS; 8 rats/cage) or sham-crowding stress (SC; 2 rats/cage) for up to 15 consecutive days. Hypothalamic-pituitary-adrenal (HPA) axis activity was evaluated. Intestinal tissues were obtained 1h, 1, 7, or 30 days after stress exposure, to assess neutrophil infiltration, epithelial ion transport, mitochondrial function, and CRF receptors expression. Colonic response to CRF (10 μg/kg i.p.) and hyperalgesia were evaluated after ending stress exposure. Chronic psychosocial stress activated HPA axis and induced reversible intestinal mucosal inflammation. Epithelial permeability and conductance were increased in CS rats, effect that lasted for up to 7 days after stress cessation. Visceral hypersensitivity persisted for up to 30 days post stress. Abnormal colonic response to exogenous CRF lasted for up to 7 days after stress. Mitochondrial activity was disturbed throughout the intestine, although mitochondrial response to CRF was preserved. Colonic expression of CRF receptor type-1 was increased in CS rats, and negatively correlated with body weight gain. In conclusion, chronic psychosocial stress triggers reversible inflammation, persistent epithelial dysfunction, and colonic hyperalgesia. These findings support crowding stress as a suitable animal model to unravel the complex pathophysiology underlying to common human intestinal stress-related disorders, such as IBS.

Mechanisms underlying visceral hypersensitivity in irritable bowel syndrome

Visceral hypersensitivity is currently considered a key pathophysiological mechanism involved in pain perception in large subgroups of patients with functional gastrointestinal disorders, including irritable bowel syndrome (IBS). In IBS, visceral hypersensitivity has been described in 20%-90% of patients. The contribution of the central nervous system and psychological factors to visceral hypersensitivity in patients with IBS may be significant, although still debated. Peripheral factors have gained increasing attention following the recognition that infectious enteritis may trigger the development of persistent IBS symptoms, and the identification of mucosal immune, neural, endocrine, microbiological, and intestinal permeability abnormalities. Growing evidence suggests that these factors play an important role in pain transmission from the periphery to the brain via sensory nerve pathways in large subsets of patients with IBS. In this review, we will report on recent data on mechanisms involved in visceral hypersensitivity in IBS, with particular attention paid to peripheral mechanisms.

Do interactions between stress and immune responses lead to symptom exacerbations in irritable bowel syndrome?

Irritable bowel syndrome (IBS) is a common, debilitating gastrointestinal (GI) disorder, with a worldwide prevalence of between 10% and 20%. This functional gut disorder is characterized by episodic exacerbations of a cluster of symptoms including abdominal pain, bloating and altered bowel habit, including diarrhea and/or constipation. Risk factors for the development of IBS include a family history of the disorder, childhood trauma and prior gastrointestinal infection. It is generally accepted that brain-gut axis dysfunction is fundamental to the development of IBS; however the underlying pathophysiological mechanisms remain elusive. Additional considerations in comprehending the chronic relapsing pattern that typifies IBS symptoms are the effects of both psychosocial and infection-related stresses. Indeed, co-morbidity with mood disorders such as depression and anxiety is common in IBS. Accumulating evidence points to a role for a maladaptive stress response in the initiation, persistence and severity of IBS-associated symptom flare-ups. Moreover, mechanistically, the stress-induced secretion of corticotropin-releasing factor (CRF) is known to mediate changes in GI function. Activation of the immune system also appears to be important in the generation of IBS symptoms and increasing evidence now implicates low-grade inflammation or immune activation in IBS pathophysiology. There is a growing body of research focused on understanding at a molecular, cellular and in vivo level, the relationship between the dysregulated stress response and immune system alterations (either individually or in combination) in the etiology of IBS and to the occurrence of symptoms.

Effect of self-management intervention on cortisol and daily stress levels in irritable bowel syndrome

Self-management programs that include cognitive behavioral strategies have been shown to improve gastrointestinal (GI) symptoms, psychological distress, and quality of life (QoL) in persons with irritable bowel syndrome (IBS). However, less is known about the physiological impact of such a change. As part of a randomized controlled trial using a comprehensive self-management (CSM) intervention (n = 126) compared to usual care (UC; n = 62), cortisol levels were measured in 4 weekly first morning urine samples at baseline and at 3-, 6-, and 12-month follow-up. In addition, diary (28 days) ratings of stress were recorded at baseline, 3, 6, and 12 months. The omnibus test of all three outcome times showed no differences in urine cortisol levels between the CSM and UC groups (p = .400); however, at 3 months the CSM group had significantly higher cortisol levels than the UC group (p = .012). The CSM group reported lower daily stress levels (p = .046 from the omnibus test of all 3 time points) than the UC group, with the effect getting stronger over time. Despite marked improvements in reported stress and previously reported GI and psychological distress symptoms at later follow-ups, the CSM program did not reduce urine cortisol levels in adults with IBS. These results suggest that the first-void urine cortisol levels are not reflective of self-reported daily stress in this patient population.

Community-based study on psychological comorbidity in functional gastrointestinal disorder

Functional gastrointestinal disorder (FGID) is one of the commonest digestive diseases worldwide. Current evidence supports a bio-psycho-social pathophysiological model for FGID, which underscores the importance of psychological and social factors in development of FGID. Concomitant psychological disorders, which include anxiety, depression and somatization, have been shown to be associated with FGID in both specialist and community-based studies. This suggests that the association is genuine rather than biased observation in referral centers. Furthermore, psychological distress such as depression, anxiety and phobia are strongly correlated with severity of FGID symptoms. There are biologically plausible mechanisms that support the causal role of psychological disorders in FGID. Psychological distress, in particular anxiety, can induce aggravation of visceral hyperalgesia as well as hypervigilance in FGID patients. This leads to poorer quality of life and increased utilization of healthcare service in addition to worsening of symptoms. Despite the numerous reports on the potential therapeutic value of psychotropic agents and psychological intervention, the importance of screening for concomitant psychological disorder in FGID patients has not been fully recognized in daily practice. Most FGID patients tend to have very low awareness of their mood symptoms, which lead to delayed diagnosis, deterioration of disease and unnecessary investigations. Many of these patients may be reluctant to accept the diagnosis of concomitant psychological disorders and therefore a good doctor-patient rapport and therapeutic relationship are essential for management of these patients.

Pooled analysis of brain activity in irritable bowel syndrome and controls during rectal balloon distension

BACKGROUND

Brain-imaging literature of irritable bowel syndrome (IBS) suggests an abnormal brain-gut communication. We analyzed the literature to evaluate and compare the aspects of brain activity in individuals with IBS and control subjects experiencing controlled rectal stimulation.

METHODS

PubMed was searched until September 2010. Data from 16 articles reporting brain activity during rectal balloon distensions in IBS compared to control groups was analyzed. Prevalence rates and pairwise activations were assessed using binomial distributions for 11 selected regions of interest. The data were aggregated to adjust for center effect.

KEY RESULTS

There was considerable variability in the literature regarding regions and their activity patterns in controls and individuals with IBS. There was no significant difference found in the thalamus, anterior cingulate cortex, posterior cingulate cortex, and prefrontal cortex, however, results show limited evidence of consensus for the anterior insula (AI) (P = 0.22). Pairwise activity results suggest that pairs involving the AI tend to have more consistent activity together than pairs which do not involve the AI (posterior insula and AI, P = 0.08; posterior cingulate cortex and AI, P = 0.16), however, no pairwise evaluation reached significance.

CONCLUSIONS & INFERENCES

Our pooled analysis demonstrates that the literature reports are quite heterogeneous but there is some evidence that there may be patterns of higher activity more common in individuals with IBS than in controls. A consensus, though, regarding study designs, analysis approach and reporting could create a clearer understanding of brain involvement in IBS pathophysiology.

The role of stress on physiologic responses and clinical symptoms in irritable bowel syndrome

Studies support the concept that irritable bowel syndrome (IBS) is a biopsychosocial disorder that can be explained by a neurobiological model which postulates stress-induced alterations in central stress and arousal circuits and activation of parallel motor outputs from brain regions that can affect bodily function and behavior. Sustained stress can result in chronic overactivity or underactivity of allostatic (or adaptive) systems, including the hypothalamic-pituitary-adrenal (HPA) axis, autonomic nervous system, metabolic, and immune systems, can occur. Animal and human studies have demonstrated that chronic or sustained stress is associated with the onset and exacerbation of symptoms of IBS. Chronic stress is also an independent predictor of developing post-infectious IBS. IBS patients specifically show stress-induced alterations in gastrointestinal motility, rectal perception, autonomic tone and HPA axis responses, although these findings are not entirely consistent among studies. This can be in part due to differences in study methodology or to various factors that can affect these physiologic responses. A greater recognition and understanding of the effects of stress in IBS may help identify targets for future drug development and also help guide more effective management of IBS symptoms.

Meta-analysis and meta-regression of hypothalamic-pituitary-adrenal axis activity in functional somatic disorders

Dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis is the most investigated biological risk marker in functional somatic disorders (FSDs), such as chronic fatigue syndrome (CFS), fibromyalgia (FM), and irritable bowel syndrome (IBS). Our aim was to assess whether there is an association between basal hypocortisolism and FSD and to identify potential moderators of this association. Meta-analysis on 85 studies revealed that although basal cortisol levels were generally lower in FSD subjects compared to controls, this association did not reach statistical significance (SMD -0.07, 95% CI -0.17 to 0.04, p=0.241). However, when the three FSD were assessed separately, statistically significant basal hypocortisolism was observed in CFS subjects compared to controls (SMD -0.14, 95% CI -0.28 to 0.00, p=0.047), but not in FM or IBS. When all potential moderators were entered into a meta-regression analysis, only type of FSD and female gender were significant independent predictors of basal hypocortisolism. In conclusion, we did not find evidence to consider all three main FSD as hypocortisolemic disorders, as significant reduction in basal cortisol compared to healthy controls was only found in CFS and in females with FM, but not in IBS.

The role of experimental models in developing new treatments for irritable bowel syndrome

Irritable bowel syndrome (IBS) is characterized by chronic, recurrent abdominal pain and altered bowel habits and is currently defined by symptom criteria and the absence of detectable organic disease. The underlying pathophysiology remains incompletely understood. Despite considerable efforts by the scientific community and the pharmaceutical industry to develop novel pharmacological treatments aimed at chronic visceral pain, the traditional approach to identifying and evaluating novel drugs for this target have largely failed to translate into effective IBS treatments. However, several novel drugs aimed at normalizing bowel movements have produced clinical effects, not only on the primary target, but also on pain and discomfort. While some of the commonly used experimental animal models for the pain dimension of IBS have some face and construct validity, the predictive validity of most of the models is either unknown, or has been disappointing. A reverse translational approach is proposed, which is based on identification and characterization of brain endophenotypes in patients, followed by translation of these endophenotypes for pharmacological studies in rodent models.

Protocol for a randomized controlled study of Iyengar yoga for youth with irritable bowel syndrome

Introduction

Irritable bowel syndrome affects as many as 14% of high school-aged students. Symptoms include discomfort in the abdomen, along with diarrhea and/or constipation and other gastroenterological symptoms that can significantly impact quality of life and daily functioning. Emotional stress appears to exacerbate irritable bowel syndrome symptoms suggesting that mind-body interventions reducing arousal may prove beneficial. For many sufferers, symptoms can be traced to childhood and adolescence, making the early manifestation of irritable bowel syndrome important to understand. The current study will focus on young people aged 14-26 years with irritable bowel syndrome. The study will test the potential benefits of Iyengar yoga on clinical symptoms, psychospiritual functioning and visceral sensitivity. Yoga is thought to bring physical, psychological and spiritual benefits to practitioners and has been associated with reduced stress and pain. Through its focus on restoration and use of props, Iyengar yoga is especially designed to decrease arousal and promote psychospiritual resources in physically compromised individuals. An extensive and standardized teacher-training program support Iyengar yoga's reliability and safety. It is hypothesized that yoga will be feasible with less than 20% attrition; and the yoga group will demonstrate significantly improved outcomes compared to controls, with physiological and psychospiritual mechanisms contributing to improvements.

Methods/Design

Sixty irritable bowel syndrome patients aged 14-26 will be randomly assigned to a standardized 6-week twice weekly Iyengar yoga group-based program or a wait-list usual care control group. The groups will be compared on the primary clinical outcomes of irritable bowel syndrome symptoms, quality of life and global improvement at post-treatment and 2-month follow-up. Secondary outcomes will include visceral pain sensitivity assessed with a standardized laboratory task (water load task), functional disability and psychospiritual variables including catastrophizing, self-efficacy, mood, acceptance and mindfulness. Mechanisms of action involved in the proposed beneficial effects of yoga upon clinical outcomes will be explored, and include the mediating effects of visceral sensitivity, increased psychospiritual resources, regulated autonomic nervous system responses and regulated hormonal stress response assessed via salivary cortisol.

Trial registration

ClinicalTrials.gov NCT01107977.

Blunted affect is associated with hypothalamic--pituitary--adrenal axis (HPA) hypoactivity and elevated CSF-interleukin-1 beta (IL-1β) in response to lumbar puncture

OBJECTIVE

Proinflammatory activity has been suggested as one of the psychophysiological mechanisms responsible for the health risks associated with stress and mood disorders. There have been limited studies evaluating central immune and hypothalamic- pituitary-adrenal (HPA) axis responses to experimental stress in healthy women. The current study compared, under a controlled condition, the baseline measures and biological and psychological responses to a physical stressor (lumbar puncture [LP]) of healthy women who exhibited an abnormal serum cortisol response (nonresponders [NRs]) to the LP to those of normal controls (responders [Rs]), allowing assessment of stress responsivity and the functional integrity of the feedback system of the HPA axis, sympathetic nervous system (SNS), and neuroimmune axis.

METHOD

Serum adrenocorticotropic hormone (ACTH), cortisol, interleukin (IL)-6, IL-1sR, and central IL-1β, IL-6, norepineprhine (NE), corticotropin-releasing factor (CRF), and affective states (using the Stress Symptom Rating Questionnaire) were measured in five NRs and seven Rs.

RESULTS

Compared with NR subjects, Rs had significantly higher levels of ACTH and central IL-1β, higher ratings of attention, and lower perceived stress and anxiety. There were no differences between the groups in serum cortisol, IL-6, or IL-1sR or in central IL-6, NE, and CRF.

CONCLUSIONS

Women with significantly elevated IL-1β (NRs) responded to an extreme physical stressor with an attenuated HPA system and abnormal subjective ratings compared to healthy women with lower values of central IL-1β. These findings support the suppression of the effects of HPA-axis cortisol on proinflammatory cytokine production. It is possible that these differences in the psychoneuroimmunological profiles of NRs will lead to increased psychobiological vulnerability and predict future health risk.

Gating of sensory information differs in patients with interstitial cystitis/painful bladder syndrome

PURPOSE

Altered sensory processing in interstitial cystitis/painful bladder syndrome cases may result from a deficiency of the central nervous system to adequately filter incoming visceral afferent information. We used prepulse inhibition as an operational measure of sensorimotor gating to examine early pre-attentive stages of information processing in females with interstitial cystitis/painful bladder syndrome and healthy controls.

MATERIALS AND METHODS

We assessed prepulse inhibition in 14 female patients with interstitial cystitis/painful bladder syndrome and 17 healthy controls at 60 and 120-millisecond prepulse-to-startle stimulus intervals. We evaluated group differences in prepulse inhibition, and relationships between prepulse inhibition, neuroticism and acute stress ratings.

RESULTS

Patients showed significantly decreased prepulse inhibition at 60 and 120-millisecond prepulse intervals. The prepulse inhibition deficit was related to acute stress ratings in the patients. However, increased neuroticism appeared to mitigate the prepulse inhibition deficit in those with interstitial cystitis/painful bladder syndrome, possibly reflecting greater vigilance.

CONCLUSIONS

Compared to healthy controls, female patients with interstitial cystitis/painful bladder syndrome had decreased ability to adequately filter incoming information and perform appropriate sensorimotor gating. These results suggest that a possible mechanism for altered interoceptive information processing in interstitial cystitis/painful bladder syndrome cases may be a general deficit in filtering mechanisms due to altered pre-attentive processing.

Relationships between Irritable Bowel Syndrome Pain, Skin Temperature Indices of Autonomic Dysregulation, and Sensitivity to Thermal Cutaneous Stimulation

This study evaluated relationships between irritable bowel syndrome (IBS) pain, sympathetic dysregulation, and thermal pain sensitivity. Eight female patients with diarrhea-predominant IBS and ten healthy female controls were tested for sensitivity to thermal stimulation of the left palm. A new method of response-dependent thermal stimulation was used to maintain pain intensity at a predetermined level (35%) by adjusting thermal stimulus intensity as a function of pain ratings. Clinical pain levels were assessed prior to each testing session. Skin temperatures were recorded before and after pain sensitivity testing. The temperature of palmar skin dropped (1.5°C) when the corresponding location on the opposite hand of control subjects was subjected to prolonged thermal stimulation, but this response was absent for IBS pain patients. The patients also required significantly lower stimulus temperatures than controls to maintain a 35% pain rating. Baseline skin temperatures of patients were significantly correlated with thermode temperatures required to maintain 35% pain ratings. IBS pain intensity was not significantly correlated with skin temperature or pain sensitivity. The method of response-dependent stimulation revealed thermal hyperalgesia and increased sympathetic tone for chronic pain patients, relative to controls. Similarly, a significant correlation between resting skin temperatures and thermal pain sensitivity for IBS but not control subjects indicates that tonic sympathetic activation and a thermal hyperalgesia were generated by the chronic presence of visceral pain. However, lack of a significant relationship between sympathetic tone and ratings of IBS pain casts doubt on propositions that the magnitude of IBS pain is determined by psychological stress.

Quantitative assessment and characterization of visceral hyperalgesia evoked by esophageal balloon distention and acid perfusion in patients with functional heartburn, nonerosive reflux disease, and erosive esophagitis

BACKGROUND AND OBJECTIVES

The role of esophageal hypersensitivity in functional heartburn (FH) with negative pH test, negative symptom index, and the proton pump inhibitor (PPI) failure has not been established. The aim of this study was to investigate the characterization of visceral hyperalgesia evoked by esophageal balloon distention and acid perfusion in patients with FH, nonerosive reflux disease, and erosive esophagitis and further characterize the pathophysiologic mechanism of FH.

METHODS

A total of 21 FH patients (with esophageal acid exposure <3.1% and a symptom index<50% and nonresponse to a therapeutic trial with proton pump inhibitors, 25 Nonerosive reflux disease (NERD) patients (with esophageal acid exposure>4%), 23 erosive esophagitis (EE) patients (LA grade B to D), and 18 healthy controls were recruited in the study. Mechanosensitivity including the initial perception threshold (IPT) and pain threshold (PT) was evaluated by using a Barostat with a double-random staircase distension protocol. Chemosensitivity was graded along a visual analog scale after perfusion of saline and 0.1 N HCl.

RESULTS

The baseline IPTs and PTs were all lower in patients with FH, NERD, and EE than in the controls (all P<0.01). In addition, the baseline PT in FH patients was significantly lower than those in NERD (P=0.015) and EE patients (P<0.001). After acid perfusion, the mean symptom intensity scores were significantly greater in patients with FH, NERD, and EE than those in the controls (all P<0.001). The postacid perfusion IPTs in patients with FH, NERD, and EE were all significantly lower than the corresponding baseline values (all P<0.01). The PTs in FH (P=0.026) and EE patients (P<0.001) were significantly lower than the corresponding baseline values. Moreover, the postacid perfusion PT was significantly lower in FH patients than in NERD patients (P<0.001).

CONCLUSIONS

FH patients are more sensitive to mechanical or chemical stimuli than NERD patients. Sensitization of esophageal acid-sensitive chemoreceptors may exert a significant influence on the pressure-sensitive mechanoreceptors, and there is the cooperative interaction in the process of esophageal visceral hyperalgesia.

Asian consensus on irritable bowel syndrome

BACKGROUND AND AIMS

Many of the ideas on irritable bowel syndrome (IBS) are derived from studies conducted in Western societies. Their relevance to Asian societies has not been critically examined. Our objectives were to bring to attention important data from Asian studies, articulate the experience and views of our Asian experts, and provide a relevant guide on this poorly understood condition for doctors and scientists working in Asia.

METHODS

A multinational group of physicians from Asia with special interest in IBS raised statements on IBS pertaining to symptoms, diagnosis, epidemiology, infection, pathophysiology, motility, management, and diet. A modified Delphi approach was employed to present and grade the quality of evidence, and determine the level of agreement.

RESULTS

We observed that bloating and symptoms associated with meals were prominent complaints among our IBS patients. In the majority of our countries, we did not observe a female predominance. In some Asian populations, the intestinal transit times in healthy and IBS patients appear to be faster than those reported in the West. High consultation rates were observed, particularly in the more affluent countries. There was only weak evidence to support the perception that psychological distress determines health-care seeking. Dietary factors, in particular, chili consumption and the high prevalence of lactose malabsorption, were perceived to be aggravating factors, but the evidence was weak.

CONCLUSIONS

This detailed compilation of studies from different parts of Asia, draws attention to Asian patients' experiences of IBS.

Asian motility studies in irritable bowel syndrome

Altered motility remains one of the important pathophysiologic factors in patients with irritable bowel syndrome (IBS) who commonly complain of abdominal pain and stool changes such as diarrhea and constipation. The prevalence of IBS has increased among Asian populations these days. Gastrointestinal (GI) physiology may vary between Asian and Western populations because of differences in diets, socio-cultural backgrounds, and genetic factors. The characteristics and differences of GI dysmotility in Asian IBS patients were reviewed. MEDLINE search work was performed including following terms, 'IBS,' 'motility,' 'transit time,' 'esophageal motility,' 'gastric motility,' 'small intestinal motility,' 'colonic motility,' 'anorectal function,' and 'gallbladder motility' and over 100 articles were categorized under 'esophagus,' 'stomach,' 'small intestine,' 'colon,' 'anorectum,' 'gallbladder,' 'transit,' 'motor pattern,' and 'effect of stressors.' Delayed gastric emptying, slow tansit in constipation predominant IBS patients, rapid transit in diarrhea predominant IBS patients, accelerated motility responses to various stressors such as meals, mental stress, or corticotrophin releasing hormones, and altered rectal compliance and altered rectal accomodation were reported in many Asian studies regarding IBS. Many conflicting results were found among these studies and there are still controversies to conclude these as unique features of Asian IBS patients. Multinational and multicenter studies are needed to be performed vigorously in order to elaborate characteristics as well as differences of altered motililty in Asian patients with IBS.

Guanylate cyclase C-mediated antinociceptive effects of linaclotide in rodent models of visceral pain

BACKGROUND Linaclotide is a novel, orally administered investigational drug currently in clinical development for the treatment of constipation-predominant irritable bowel syndrome (IBS-C) and chronic idiopathic constipation. Visceral hyperalgesia is a major pathophysiological mechanism in IBS-C. Therefore, we investigated the anti-nociceptive properties of linaclotide in rodent models of inflammatory and non-inflammatory visceral pain and determined whether these pharmacological effects are linked to the activation of guanylate cyclase C (GC-C). METHODS Orally administered linaclotide was evaluated in non-inflammatory acute partial restraint stress (PRS) and acute water avoidance stress (WAS) models in Wistar rats, and in a trinitrobenzene sulfonic acid (TNBS)-induced inflammatory model in Wistar rats and GC-C null mice. KEY RESULTS In TNBS-induced colonic allodynia, linaclotide significantly decreased the number of abdominal contractions in response to colorectal distension without affecting the colonic wall elasticity change in response to distending pressures after TNBS. However, linaclotide had no effect on visceral sensitivity under basal conditions. In addition, linaclotide significantly decreased colonic hypersensitivity in the PRS and WAS models. In wild type (wt) and GC-C null mice, the instillation of TNBS induced similar hyperalgesia and allodynia. However, in post-inflammatory conditions linaclotide significantly reduced hypersensitivity only in wt mice, but not in GC-C null mice. CONCLUSIONS & INFERENCES These findings indicate that linaclotide has potent anti-nociceptive effects in several mechanistically different rodent models of visceral hypersensitivity and that these pharmacological properties of linaclotide are exerted through the activation of the GC-C receptor. Therefore, linaclotide may be capable of decreasing abdominal pain in patients suffering from IBS-C.

Increased auditory startle reflex in children with functional abdominal pain

OBJECTIVE

To test the hypothesis that children with abdominal pain-related functional gastrointestinal disorders have a general hypersensitivity for sensory stimuli.

STUDY DESIGN

Auditory startle reflexes were assessed in 20 children classified according to Rome III classifications of abdominal pain-related functional gastrointestinal disorders (13 irritable bowel syndrome [IBS], 7 functional abdominal pain syndrome; mean age, 12.4 years; 15 girls) and 23 control subjects (14 girls; mean age, 12.3 years) using a case-control design. The activity of 6 left-sided muscles and the sympathetic skin response were obtained by an electromyogram. We presented sudden loud noises to the subjects through headphones.

RESULTS

Both the combined response of 6 muscles and the blink response proved to be significantly increased in patients with abdominal pain compared with control subjects. A significant increase of the sympathetic skin response was not found. Comorbid anxiety disorders (8 patients with abdominal pain) or Rome III subclassification did not significantly affect these results.

CONCLUSIONS

This study demonstrates an objective hyperresponsivity to nongastrointestinal stimuli. Children with abdominal pain-related functional gastrointestinal disorders may have a generalized hypersensitivity of the central nervous system.

Prevalence and risk factors of irritable bowel syndrome in healthy screenee undergoing colonoscopy and laboratory tests

INTRODUCTION

The prevalence of irritable bowel syndrome (IBS) after excluding organic disease has not been reported in Korea.

METHODS

Of 5,605 participants in a health screening program, inclusion criteria were persons who underwent colonoscopy and completed questionnaires. Exclusion criteria were persons diagnosed with colon cancer, inflammatory bowel disease, previous colectomy, and abnormal results of thyroid function tests. IBS was defined by Rome III criteria. Physical and psychological stress was evaluated with visual analogue scales, ranging from 0 to 10. Risk factors for IBS were estimated with odds ratios (OR) and 95% confidence intervals (CI) using logistic regression analysis.

RESULTS

The prevalence of IBS was 8.2% (5,605) in the total population and 9.1% (393/4,296) in the final study sample. IBS had a positive association with female sex (adjusted OR, 1.33; 95% CI, 1.00-1.79; p = 0.05) and current smoking (adjusted OR, 1.31; 95% CI, 1.00-1.71; p = 0.05). The prevalence of IBS increased with increased psychological stress (adjusted p for trend = 0.005) and decreased with increasing age (adjusted p for trend <0.001), with adjusted OR of 0.95 (95% CI, 0.68-1.33) for age of 40.0 to 49.9 years; 0.79 (95% CI, 0.54-1.15) for age of 50.0 to 59.9 years; and 0.51 (95% CI, 0.30-0.86) for age of 60 years or more, compared with age less than 40 years. Drinking status, body mass index, hypertension, diabetes, and use of sedatives had no association with IBS.

CONCLUSIONS

The prevalence of IBS increased with decreasing age and increasing psychological stress, and was positively associated with female sex and current smoking.

Hypothalamic--pituitary-- adrenal axis dysregulation in women with irritable bowel syndrome in response to acute physical stress

Irritable bowel syndrome (IBS) supports the concept of a dysregulated hypothalamic-pituitary-adrenal (HPA) axis. This study investigates the neuroendocrine and psychological responses to the acute physical stress of a lumbar puncture (LP) in women with diarrhea-predominant IBS by assessing central and peripheral HPA activity and affective measures. Blood samples have been collected at baseline and immediately post- and 1 hr following LP from 13 women with IBS and 13 controls. Plasma adrenocorticotropic hormone (ACTH), cortisol, epinephrine, and norepinephrine levels are analyzed. A single measure of cerebrospinal fluid (CSF) concentrations of corticotropin-releasing factor (CRF(CSF)) and norepinephrine(CSF) is noted. Affective assessments are used to rate anxiety and depression with the Hospital Anxiety and Depression Scale (HADS) and acute mood state is rated using the Stress Symptom Rating questionnaire (stress, anxiety, anger, arousal). The women with IBS display blunted ACTH and cortisol responses to the LP along with a profile of affective responsiveness suggestive of chronic psychosocial stress, although no CRF(CSF) differences between groups are observed.

Widespread hypersensitivity is related to altered pain inhibition processes in irritable bowel syndrome

The mechanisms of chronic pain in irritable bowel syndrome (IBS) have been widely investigated but remain unclear. The present study investigated the relation between visceral hypersensitivity, cutaneous thermal sensitivity, and central pain mechanisms. Rectal sensitivity was assessed with a barostat, and forearm and calf sensitivity with a contact thermode. Central mechanisms were assessed by counterirritation using sustained cold-pain to the hand and painful electric shocks to the ankle. Psychological symptoms were also assessed, using questionnaires. Female volunteers with diarrhea-predominant IBS (n=27) and healthy controls (n=25) participated in the study. IBS patients had lower rectal and calf pain thresholds compared to controls (p's<0.05). IBS patients also reported more pain than controls for rectal distensions, and heat pain on the calf and forearm (all p's<0.001). Cold-pain inhibited shock-pain in controls but not IBS patients (controls: -13.5+/-5.3 vs IBS: +1.9+/-10.5; p<0.01). In addition, visceral hypersensitivity was significantly correlated to cutaneous thermal hypersensitivity and pain inhibition deficits, although effects were only weak and moderate, respectively. Furthermore, covariance analyses indicated that psychological factors accounted for group differences in visceral hypersensitivity and pain inhibition deficits. In conclusion, this study confirms the relation between altered pain inhibition processes and widespread hypersensitivity in IBS. The present results also suggests that psychological symptoms and altered pain processing in IBS patients may reflect at least in part, common underlying mechanisms.

Peripheral factors in the pathophysiology of irritable bowel syndrome

The pathophysiology of IBS is complex and still incompletely known. Both central and peripheral factors are thought to contribute to the symptoms of IBS, including psychosocial factors, abnormal GI motility and secretion, and visceral hypersensitivity. In this review the involvement of peripheral factors in the pathophysiology in IBS is reviewed. Altered GI motility is commonly found in this patient group, even though a specific motor pattern has been hard to find. Colonic transit has been found to be of relevance for the bowel habit of the patient. Abnormal gas handling within the gut is also commonly seen, and seems to be one, but not the only factor responsive for bloating. There is also limited evidence supporting the presence of abnormal GI secretion in IBS, but its relevance for symptoms remains unclear. Visceral hypersensitivity is currently considered to be one of the most important pathophysiological factors in IBS. It can be modulated by several external and internal factors and recent studies support an association between colorectal sensitivity and the symptoms reported by the patients, especially pain.

Essential role for TRPV1 in stress-induced (mast cell-dependent) colonic hypersensitivity in maternally separated rats

Irritable bowel syndrome is in part characterized by an increased sensitivity to colonic distension. Stress is an important trigger factor for symptom generation. We hypothesized that stress induces visceral hypersensitivity via mast cell degranulation and transient receptor ion channel 1 (TRPV1) modulation. We used the rat model of neonatal maternal separation (MS) to investigate this hypothesis. The visceromotor response to colonic distention was assessed in adult MS and non-handled (NH) rats before and after acute water avoidance (WA) stress. We evaluated the effect of the mast cell stabilizer doxantrazole, neutralizing antiserum against the mast cell mediator nerve growth factor (NGF) and two different TRPV1 antagonists; capsazepine (non-specific) and SB-705498 (TRPV1-specific). Immunohistochemistry was used to assess post-WA TRPV1 expression in dorsal root ganglia and the presence of immunocytes in proximal and distal colon. Retrograde labelled and microdissected dorsal root ganglia sensory neurons were used to evaluate TRPV1 gene transcription. Results showed that acute stress induces colonic hypersensitivity in MS but not in NH rats. Hypersensitivity was prevented by prestress administration of doxantrazole and anti-NGF. Capsazepine inhibited and SB-705498 reversed poststress hypersensitivity. In MS rats, acute stress induced a slight increase in colonic mast cell numbers without further signs of inflammation. Post-WA TRPV1 transcription and expression was not higher in MS than NH rats. In conclusion, the present data on stress-induced visceral hypersensitivity confirm earlier reports on the essential role of mast cells and NGF. Moreover, the results also suggest that TRPV1 modulation (in the absence of overt inflammation) is involved in this response. Thus, mast cells and TRPV1 are potential targets to treat stress-induced visceral hypersensitivity.

Irritable bowel syndrome in childhood: visceral hypersensitivity and psychosocial aspects

Visceral hypersensitivity is often considered to play a major etiologic role in the pathophysiology of irritable bowel syndrome in adults, and some authors argue that this increased sensitivity is mainly due to psychological factors. In contrast, there are no data in children with irritable bowel syndrome which confirm this relationship. The aim of the study was to evaluate the relationship between psychosocial aspects and sensorymotor function in children affected by irritable bowel syndrome. Ten children fulfilling the Rome II criteria for irritable bowel syndrome and seven healthy controls were enrolled. We studied the thresholds and the perception of visceral stimuli in the rectum by means of an electronic barostat (isobaric phasic distentions, 3 mmHg/1 min, interval 1 min) and a validated questionnaire. Personality features were evaluated by means of the Big Five Questionnaire for Children. Sleep, mood disturbance, anxiety and individual performance (missed school days, school results and social activities) were also evaluated. Children with irritable bowel syndrome showed significantly lower thresholds for discomfort (14.8 +/- 3.5 vs 22.3 +/- 6.9 mmHg, P = 0.010) and a higher cumulative perception score (28.2 +/- 11.1 vs 12.3 +/- 8.0, P = 0.005) compared with healthy controls. A higher emotional instability (57.8 +/- 7.0 vs 48.7 +/- 10.1, P = 0.047), sleep disturbance (7.2 +/- 1.0 vs 9.3 +/- 0.5, P = 0.004) and anxiety (6.3 +/- 2.0 vs 2.3 +/- 1.7, P = 0.009) were observed in irritable bowel syndrome patients. Moreover, in a multivariate analysis, the cumulative perception score was significantly related to emotional instability (P = 0.042). In conclusion children with irritable bowel syndrome exhibit visceral hypersensitivity and psychosocial impairment. Emotional instability, as a personality feature in these children, seems to modulate the perception response to visceral stimulations.

Increased startle responses in interstitial cystitis: evidence for central hyperresponsiveness to visceral related threat

PURPOSE

Hypersensitivity to visceral stimuli in interstitial cystitis/painful bladder syndrome may result from enhanced responsiveness of affective circuits (including the amygdala complex) and associated central pain amplification. Potentiation of the eyeblink startle reflex under threat is mediated by output from the amygdala complex and, therefore, represents a noninvasive marker to study group differences in responsiveness in this brain circuit.

MATERIALS AND METHODS

Acoustic startle responses were examined in female patients with interstitial cystitis/painful bladder syndrome (13) and healthy controls (16) during context threat (application of muscle stimulation electrodes to the lower abdomen overlying the bladder), and cued conditions for safety (no stimulation possible), anticipation and imminent threat of aversive abdominal stimulation over the bladder.

RESULTS

Patients showed significantly greater startle responses during nonimminent threat conditions (baseline, safe and anticipation periods) while both groups showed similar robust startle potentiation during the imminent threat condition. Higher rates of anxiety and depression symptoms in the patient group did not account for the group differences in startle reflex magnitude.

CONCLUSIONS

Compared to controls, female patients with interstitial cystitis/painful bladder syndrome showed increased activation of a defensive emotional circuit in the context of a threat of abdominal pain. This pattern is similar to that previously reported in patients with anxiety disorders as well as those with irritable bowel syndrome. Since these circuits have an important role in central pain amplification related to affective and cognitive processes, these results support the hypothesis that the observed abnormality may be involved in the enhanced perception of bladder signals associated with interstitial cystitis/painful bladder syndrome.

Amitriptyline modifies the visceral hypersensitivity response to acute stress in the irritable bowel syndrome

BACKGROUND

Acute physical stress causes alteration in gut autonomic function and visceral hypersensitivity in patients with irritable bowel syndrome (IBS). We have developed a model to measure this stress response.

AIM

To assess whether treatment with a drug effective in treating IBS (amitriptyline) alters the response to acute stress in IBS patients.

METHODS

Nineteen patients with IBS were given amitriptyline 25-50 mg. Patients underwent physical stress (cold pressor) test at baseline and after 3 months of treatment. Physiological parameters measured were: stress perception; systemic autonomic tone [heart rate (HR) and blood pressure (BP)]; gut specific autonomic innervation [rectal mucosal blood flow (RMBF)] and visceral sensitivity (rectal electrosensitivity).

RESULTS

Fourteen of 19 (74%) patients improved symptomatically after 3 months of amitriptyline. Acute stress induced increased perception of stress and systemic autonomic tone and reduced RMBF in symptomatic responders and nonresponders (P > 0.05 for all). All nonresponders but only 3 of 14 responders continued to exhibit stress-induced reduced pain threshold at 3 months (change from baseline -31% vs. +2%, P < 0.03 respectively).

CONCLUSION

In this open study, amitriptyline appears to decrease stress-induced electrical hypersensitivity; this effect is independent of autonomic tone. The gut response to acute stress deserves further study as a model to study drug efficacy in IBS.

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis in irritable bowel syndrome

Enhanced stress responsiveness has been implicated as a potential mechanism contributing to the pathophysiology of irritable bowel syndrome (IBS), and should be reflected in altered function of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system. Both of these systems can modulate mucosal immune function. The aims of this study were: (i) to characterize the basal circadian rhythm of adrenocorticotropin hormone (ACTH) and cortisol in IBS vs healthy controls; (ii) to compare stimulated ACTH, cortisol and noradrenaline responses to a pelvic visceral stressor (sigmoidoscopy) in IBS and controls; and (iii) to correlate neuroendocrine responses with colonic mucosal cytokine expression and symptoms in IBS. Two separate studies were conducted in women. In Study 1, basal cortisol levels were analysed in 41 IBS and 25 controls using 24-h collections of plasma ACTH and cortisol (q10 min sampling). In Study 2, 10 IBS patients with diarrhoea (IBS-D) and 10 controls underwent sigmoidoscopy with measurements of stimulated neuroendocrine responses and cytokine mRNA expression in colonic tissue. Basal ACTH levels were significantly blunted (P < 0.05), while basal and stimulated plasma cortisol levels were higher in patients. Basal cortisol levels prior to an experimental visceral stressor positively correlated with anxiety symptoms (P < 0.004), but not IBS symptoms. Irritable bowel syndrome patients with diarrhoea had significantly decreased mRNA expression of mucosal cytokines [interleukin (IL)-2, IL-6] in the sigmoid colon vs controls (P < 0.05). Although dysregulations in stress-responsive systems such as the HPA axis and mucosal immune function are demonstrated in IBS, they do not appear to have a primary role in modulating IBS severity and abdominal pain.

The effect of chronic variable stress on bowel habit and adrenal function in rats

BACKGROUND AND AIM

Increased colonic motility is a well-known stress response and corticotropin releasing hormone plays an important role in this response, but sequential change of bowel habit and adrenal function during chronic stress has not been reported. The objective of this study was to evaluate the effect of chronic stress on bowel habit and adrenal function.

METHODS

Male Sprague-Dawley rats were exposed to chronic variable stress (CVS) for 6 weeks. We measured daily the number and weight of pellets and weekly urinary corticosterone. After 6 weeks of experiment, visceromotor response (VMR) to colorectal distention (CRD), serum corticosterone and adrenal glands weight were measured.

RESULTS

The number and weight of pellets in CVS rats was greater than those of the control rats initially and decreased during the later period. However, CVS rats showed continuously exaggerated daily variation of pellet number than control rats to the end of experimental period. Urinary corticosterone was increased in CVS rat until the fifth week, but urine and serum corticosterone were not statistically different between groups at the sixth week. However, the relative weight of adrenal glands was higher in CVS rats at the sixth week. CVS rats showed exaggerated VMR to CRD than the control rats.

CONCLUSIONS

The prolonged and variable stress to rats induced sustained bowel habit dysfunction and visceral hypersensitivity without adaptation. Chronic stress also increased adrenal activity from the early phase and finally caused adrenal hypertrophy with relatively decreased activity. But adrenal change was not parallel to bowel habit change and it remains to be seen whether adrenal dysfunction is directly related to bowel habit dysfunction.

Challenges to the therapeutic pipeline for irritable bowel syndrome: end points and regulatory hurdles

Recent advances in our understanding of basic neuroenteric mechanisms and the role of effectors and transmitters in the brain-gut axis have provided opportunities to develop new therapeutic agents for irritable bowel syndrome (IBS). Furthermore, human pharmacodynamic studies utilizing transit, colonic, or rectal sensitivity and brain imaging have been useful in determining therapeutic efficacy (particularly for drugs that act on motor function). This review provides an overview of medications that have not yet been approved for treatment of patients with IBS yet have shown promise in phase IIB trials. These include drugs that act on the serotonin receptor and transporter system: antidepressants, norepinephrine reuptake inhibitors, opioids, cholecystokinin antagonists, neurokinin-antagonists, chloride channel activators, guanylate cyclase C agonists, atypical benzodiazepines, probiotics, and antibiotics. The changing landscape in the regulatory approval process has impacted the development of IBS drugs. Guidance documents from regulatory agencies in Europe and the United States have focused on patients' reported outcomes and associated quality of life. After a decade of experience with different end points that have generated some data on psychometric validation and unprecedented information about responsiveness of the binary or global end points to drug therapy, it is necessary to pursue further validation studies before or during pivotal phase IIB or III trials. The hope of providing relief to patients should galvanize all parties to achieve these goals.

Influence of experimentally induced anxiety on rectal sensorimotor function in healthy humans

Psychological processes, especially anxiety, may have an influence on visceral perception and gastrointestinal (GI) motor function, thereby eliciting or aggravating GI symptoms. Anxiety has been shown to affect gastric sensorimotor function but it is conceivable that anxiety affects not only the stomach but also other parts of the GI tract, such as the rectum. The aim of this study was to investigate whether experimentally induced anxiety would alter rectal sensorimotor function in health. Eighteen healthy subjects (mean age 26.97 +/- 1.75 years) underwent a rectal barostat study. To assess sensitivity to rectal distension and rectal compliance, stepwise isobaric distension was performed during anxious and neutral emotional state. Two methods of emotion induction were used simultaneously: audiotape assisted recall of a neutral or anxious autobiographical experience and viewing of a set of validated neutral or fearful facial expressions. Anxiety levels were assessed by means of the Spielberger State-Trait Anxiety Inventory (STAI) and anxiety scores on a Likert scale. Anxiety scores (AUC: 2.11 +/- 1.45 vs 42.78 +/- 6.17 mm mmHg, P < 0.0001) and STAI scores (36.06 +/- 2.09 vs 45.56 +/- 2.52, P = 0.005) confirmed the efficacy of anxiety induction. Rectal compliance was not different during anxious compared with neutral emotional state (11.62 +/- 0.93 vs 10.61 +/- 0.96 mL mmHg(-1), P = NS). Pressure and volume thresholds inducing discomfort during rectal distension were not significantly different during anxious and neutral emotional state (29.33 +/- 1.41 vs 29.78 +/- 1.49 mmHg, P = NS and 249.26 +/- 16.22 vs 231.38 +/- 21.19 mL, P = NS respectively). Contrary to its influence on gastric sensorimotor function, experimentally induced anxiety does not affect rectal sensitivity or rectal compliance in healthy subjects.

Nondigestive symptoms in non-erosive reflux disease: nature, prevalence and relation to acid reflux

BACKGROUND

Nondigestive symptoms are frequent in the irritable bowel syndrome (IBS).

AIM

To characterize nondigestive symptoms in non-erosive gastro-oesophageal reflux disease (NERD) patients, as features of IBS are common in patients with NERD.

METHODS

A prospective, case-control study. NERD was defined in patients with reflux symptoms, a normal oesophageal mucosa and oesophageal pH < 4 for > or = 5% of the time during 24-h pH monitoring. Nondigestive symptoms were scored on validated scales of somatic pain, urinary, sleep and neurasthenia. IBS was defined by the Rome I criteria.

RESULTS

pH-positive NERD patients (n = 326) scored significantly higher than controls (nonpatient hospital visitors; n = 174) on all scales. The scores of pain, sleep and neurasthenia were highly specific in the discrimination of NERD patients from controls. In patients, nondigestive symptoms were independently associated with age, reflux symptoms severity and IBS status, but not with oesophageal acid exposure. NERD patients who met diagnostic criteria for IBS (49%) scored significantly higher on all the nondigestive symptoms scales than those had not met [IBS(-)]. Yet, IBS(-) patients scored significantly higher than controls on all scales.

CONCLUSIONS

Nondigestive symptoms were highly prevalent in NERD patients and were specific in their discrimination from controls. Nondigestive symptoms correlated with reflux symptoms and were predicted by IBS status.

Update on irritable bowel syndrome and gender differences

Irritable bowel syndrome (IBS) is a chronic functional GI disorder characterized by abdominal pain associated with alterations in defecation or stool frequency and consistency. In Western industrialized countries, women seek health care services for their symptoms more frequently than men. The cause of IBS is likely multifactorial involving altered motility, visceral hypersensitivity, and dysregulation of the autonomic nervous system. Many patients note that their symptoms are exacerbated by diet and stress, and women frequently report menstrual cycle fluctuations in symptoms. Current approaches to IBS management include behavioral management therapies such as dietary intake changes and stress reduction cognitive restructuring. Drug therapies are targeted at altering pain sensitivity, motility, and secretion. This review provides an overview of the pathogenesis of IBS, factors that contribute to gender differences, and current therapeutic approaches for symptom management.

Increased acoustic startle responses in IBS patients during abdominal and nonabdominal threat

BACKGROUND AND AIMS

Visceral hypersensitivity and symptom severity in Irritable Bowel Syndrome (IBS) are both exacerbated by stress. The eye-blink startle response represents a noninvasive measure of central defensive responding. Evidence for central hyperexcitability was studied in IBS patients by examining potentiation of the startle reflex to a nociceptive threat.

METHODS

Acoustic startle responses were examined in female IBS patients (n = 42) and healthy controls (n = 22) during cued periods in which an aversive abdominal or biceps stimulation was impossible (safe), possible (imminent threat) or anticipated (period just before the imminent threat), and during a threatening context (muscle stimulation pads attached but no cues for stimulation).

RESULTS

Both groups showed potentiation of startle responses during the imminent threat condition compared with both the anticipation and safe conditions. Compared with controls, IBS subjects showed significantly larger startle responses during anticipation and imminent threat conditions after receiving an initial aversive stimulation. There were no group differences during the context threat manipulation. Moreover, in IBS patients but not controls, higher neuroticism was associated with larger startle responses during safe and anticipation conditions but not imminent threat, whereas anxiety symptoms were negatively associated with startle magnitude during imminent threat.

CONCLUSIONS

Female IBS patients show increased startle responses to threat of aversive stimulation at both abdominal and nonabdominal sites compared with controls. The data represent the first demonstration of altered threat potentiated startle in a functional pain condition and provide support for the use of these paradigms in further evaluation of affective mechanisms in these disorders.

Novel techniques to study visceral hypersensitivity in irritable bowel syndrome

Visceral hypersensitivity has emerged as a key hypothesis in explaining the painful symptoms of irritable bowel syndrome (IBS), and it has been proposed as a "biologic marker" for the condition. Visceral hypersensitivity can be influenced by peripheral and central mechanisms affecting pain perception. The optimal method for its assessment in humans has not been determined. Current techniques include stimulation via the computerized barostat and electrical stimulation, response measures including the lower limb reflex, and brain imaging modalities such as functional MRI and positron emission tomography. It has been shown that IBS patients have decreased sensory thresholds to colonic and rectal balloon distention by barostat. Studies using electrical stimulation and the RIII lower limb reflex have further confirmed enhanced visceral perception in IBS. Evidence from more recent neuro-imaging studies suggests that IBS patients have abnormal activation of brain circuits involved in emotional and cognitive modulation of sensory information, resulting in ineffective pain modulation; these circuits may have a pathophysiologic role in enhancing visceral perception. There are few effective pharmacologic treatments that relieve IBS symptoms, and improved understanding of brain-gut interactions and factors relating to enhanced visceral perception may guide us in developing more efficacious treatments.

Irritable bowel syndrome subtypes differ in body awareness, psychological symptoms and biochemical stress markers

AIM: To elucidate the differences in somatic, psycho-logical and biochemical pattern between the subtypes of irritable bowel syndrome (IBS).

METHODS: Eighty IBS patients, 30 diarrhoea predominant (D-IBS), 16 constipation predominant (C-IBS) and 34 alternating IBS (A-IBS) underwent physiotherapeutic examinations for dysfunctions in body movements and awareness and were compared to an apparently healthy control group (AHC). All groups answered questionnaires for gastrointestinal and psychological symptoms. Biochemical variables were analysed in blood.

RESULTS: The D-IBS group showed less body awareness, less psychological symptoms, a more normal sense of coherence and psychosocial rating as well as higher C-peptide values. C-IBS had a higher degree of body dysfunction and psychological symptoms, as well as the lowest sense of coherence compared to controls and D-IBS. They also demonstrated the most elevated prolactin levels. A-IBS had the lowest degree of body disturbance, deteriorated quality of life and affected biochemical pattern. All subtypes had higher pain scores compared to controls. In addition they all had significantly increased triglycerides and elevated morning cortisol levels, however, without statistical significance compared with the controls.

CONCLUSION: IBS subtypes showed different profiles in body awareness, somatic and psychological symptoms and in biochemical variables. D-IBS differed compared to the other groups by lowered body awareness, less psychological symptoms and a higher sense of coherence and elevated C-peptide values. C-IBS and A-IBS subtypes suffered more from depression and anxiety, associated with a lower quality of life. These differences may be important and will be taken into account in our treatment of these patients.

Autonomic function at rest and in response to emotional and rectal stimuli in women with irritable bowel syndrome

Our aim was to study autonomic function in patients with Irritable bowel syndrome (IBS) without constipation and psychiatric comorbidity. Respiratory sinus arrhythmia (RSA) (representing cardiac vagal activity), skin conductance (representing sympathetic activity) and heart rate were measured at baseline and as a response to emotional stress and rectal discomfort in 33 women with IBS and 21 healthy women. Baseline heart rate was higher in the patients than in the healthy volunteers. Both groups had decreased RSA and increased heart rate and skin conductance level when exposed to emotional stress, but the autonomic responses did not differ significantly between the groups. At discomfort threshold the patients had increased heart rate response and skin conductance amplitude when compared to the healthy volunteers. Correlations between autonomic responses and the depression subscale of the Hospital Anxiety and Depression (HAD) score differed markedly between the diarrhea-predominant IBS patients and the IBS patients with alternating stool habits.

Acid-related oesophageal sensitivity, not dysmotility, differentiates subgroups of patients with non-erosive reflux disease

BACKGROUND

Patients with non-erosive reflux disease can experience reflux symptoms with similar frequency and severity as those with erosive reflux disease. Oesophageal motility and acid sensitivity are thought to influence symptom occurrence.

AIM

To compare the effect of infused hydrochloric acid on oesophageal physiology in patients with non-erosive reflux disease and erosive reflux disease.

METHODS

Twelve healthy controls and 39 patients with reflux disease [14 erosive reflux disease, 11 non-erosive reflux disease with normal (functional heartburn) and 14 non-erosive reflux disease with excess acid exposure] had hydrochloric acid and saline infused into distal and then proximal oesophagus. Oesophageal contraction amplitude, lower oesophageal sphincter pressure and pain intensity were documented at baseline and during each infusion.

RESULTS

Patients with non-erosive reflux disease had higher pain sensitivity to acid than those with erosive reflux disease and controls. Proximal acid infusion caused greater pain than distal in patients with non-erosive reflux disease. Acid and saline sensitivity were more pronounced in patients with functional heartburn. Lower oesophageal sphincter pressure and oesophageal contraction amplitudes were lower in the erosive reflux disease and non-erosive reflux disease groups, but did not change during infusions.

CONCLUSIONS

Patients with non-erosive reflux disease and, to a lesser extent, patients with erosive reflux disease, are sensitive to acid in the oesophagus, being more sensitive to proximal acid. Hypersensitivity is most marked in functional heartburn patients. This acid sensitivity is not associated with motility change.

The effect of auditory stress on perception of intraesophageal acid in patients with gastroesophageal reflux disease

BACKGROUND & AIMS

Most patients with gastroesophageal reflux disease (GERD) report that stress exacerbates their symptoms, yet mechanisms underlying this association remain unknown. We sought to determine the effect of an acute laboratory stressor on perceptual and emotional responses to intraesophageal acid perfusion in healthy controls and patients with GERD.

METHODS

Forty-six patients with heartburn and 10 healthy controls underwent upper endoscopy and, if negative, pH monitoring. Assessment of psychologic factors and health-related quality of life was done by a questionnaire. Perceptual and emotional responses to intraesophageal acid at baseline, during auditory stress, and during an auditory control condition were determined using a randomized crossover design. Plasma levels of norepinephrine, adrenocorticotropic hormone, and cortisol were assessed.

RESULTS

Twenty-nine subjects were identified as nonerosive reflux disease and 17 as erosive esophagitis. Quality of life, psychologic profile, and personality assessment variables were similar among the 2 patient groups and the controls. There was a significant reduction in mean lag time to initial symptom perception and an increase in mean intensity rating and mean acid perfusion sensitivity score in the 2 patient groups during the stress period, which was not seen during the control condition. Healthy controls demonstrated lack of a significant change in all parameters of stimulus response functions to acid, regardless of condition.

CONCLUSIONS

Acute auditory stress can exacerbate heartburn symptoms in GERD patients by enhancing perceptual response to intraesophageal acid exposure. This greater perceptual response is associated with greater emotional responses to the stressor.

Reduced brainstem inhibition during anticipated pelvic visceral pain correlates with enhanced brain response to the visceral stimulus in women with irritable bowel syndrome

Cognitive factors such as fear of pain and symptom-related anxiety play an important role in chronic pain states. The current study sought to characterize abnormalities in preparatory brain response before aversive pelvic visceral distention in irritable bowel syndrome (IBS) patients and their possible relationship to the consequences of distention. The brain functional magnetic resonance imaging (fMRI) blood oxygen level-dependent (BOLD) response to anticipated and delivered mild and moderate rectal distention was recorded from 14 female IBS patients and 12 healthy controls. During cued anticipation of distention, activity decreased in the insula, supragenual anterior cingulate cortex (sACC), amygdala, and dorsal brainstem (DBS) of controls. IBS patients showed less anticipatory inactivation. Group differences were significant in the right posterior insula and bilateral DBS. Self-rated measures of negative affect during scanning were higher in patients than controls (p < 0.001), and the anticipatory BOLD decreases in DBS were inversely correlated with these ratings. During subsequent distention, both groups showed activity increases in insula, dorsal ACC, and DBS and decreases in the infragenual ACC. The increases were more extensive in patients, producing significant group differences in dorsal ACC and DBS. The amplitude of the anticipatory decrease in the pontine portion of DBS was associated with greater activation during distention in right orbitofrontal cortex and bilateral sACC. Both regions have been associated previously with corticolimbic inhibition and cognitive coping. Deficits in preparatory inhibition of DBS, including the locus ceruleus complex and parabrachial nuclei, may interfere with descending corticolimbic inhibition and contribute to enhanced brain responsiveness and perceptual sensitivity to visceral stimuli in IBS.

Sleep deprivation is hyperalgesic in patients with gastroesophageal reflux disease

BACKGROUND & AIMS

Studies have demonstrated that gastroesophageal reflux disease (GERD) can cause sleep deprivation because of nighttime heartburn or short, amnestic arousals during sleep. Sleep deprivation has been associated with reports of increased GERD severity. Our aim was to determine whether sleep deprivation enhances perception of intraesophageal acid in patients with GERD vs healthy controls.

METHODS

Ten healthy controls and 10 patients with erosive esophagitis (grades B-D) were included in the study. All subjects were randomized to either sleep deprivation (1 night with </=3 hours of sleep) or sufficient sleep (3 days with >/=7 hours sleep/night). Patients crossed over to the other arm after a washout period of 1 week. To ensure proper sleep time, we objectively monitored subjects with an actigraph. The morning after sufficient sleep or sleep deprivation, patients underwent stimulus response functions to esophageal acid perfusion.

RESULTS

Ten healthy controls and 10 GERD patients completed all stages of the study. GERD patients demonstrated a significant decrease in lag time to symptom report (91 +/- 21.6 vs 282.7 +/- 67 sec, respectively, P = .02), increase in intensity rating (9.3 +/- 1.4 vs 4.4 +/- 0.9 cm, respectively, P = .02), and increase in acid perfusion sensitivity score (48.3 +/- 8.5 vs 22.7 +/- 4.5 sec x cm/100, respectively, P = .02) after sleep deprivation as compared with nights of good sleep. Normal subjects did not demonstrate any differences in stimulus response functions to acid between sufficient sleep and sleep deprivation (578 +/- 164 vs 493.8 +/- 60.3 sec, 0.3 +/- 0.2 vs 0.45 +/- 0.2 cm, and 0.4 +/- 0.3 vs 2.4 +/- 1.4 sec x cm/100, respectively, all P = NS).

CONCLUSIONS

Sleep deprivation is hyperalgesic in patients with GERD and provides a potential mechanism for increase in GERD symptom severity in sleep-deprived patients.