Differential responding of autonomic function to histamine H₁ antagonism in irritable bowel syndrome

Neurotransmitter and Intestinal Interactions: Focus on the Microbiota-Gut-Brain Axis in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder of unknown etiology. IBS is caused by a disruption in the gut-brain axis. Given the importance of the gut microbiota in maintaining local and systemic homeostasis of immunity, endocrine, and other physiological processes, the microbiota-gut-brain axis has been proposed as a key regulator in IBS. Neurotransmitters have been shown to affect blood flow regulation, intestinal motility, nutrient absorption, the gastrointestinal immune system, and the microbiota in recent studies. It has the potential role to play a function in the pathophysiology of the gastrointestinal and neurological systems. Transmitters and their receptors, including 5-hydroxytryptamine, dopamine, γ-aminobutyric acid, and histamine, play an important role in IBS, especially in visceral sensitivity and gastrointestinal motility. Studies in this field have shed light on revealing the mechanism by which neurotransmitters act in the pathogenesis of IBS and discovering new therapeutic strategies based on traditional pharmacological approaches that target the nervous system or novel therapies that target the microbiota.

Food Intolerance: The Role of Histamine

Histamine is a natural amine derived from L-histidine. Although it seems that our knowledge about this molecule is wide and diverse, the importance of histamine in many regulatory processes is still enigmatic. The interplay between different types of histamine receptors and the compound may cause ample effects, including histamine intoxication and so-called histamine intolerance or non-allergic food intolerance, leading to disturbances in immune regulation, manifestation of gastroenterological symptoms, and neurological diseases. Most cases of clinical manifestations of histamine intolerance are non-specific due to tissue-specific distribution of different histamine receptors and the lack of reproducible and reliable diagnostic markers. The diagnosis of histamine intolerance is fraught with difficulties, in addition to challenges related to the selection of a proper treatment strategy, the regular course of recovery, and reduced amelioration of chronic symptoms due to inappropriate treatment prescription. Here, we reviewed a history of histamine uptake starting from the current knowledge about its degradation and the prevalence of histamine precursors in daily food, and continuing with the receptor interactions after entering and the impacts on the immune, central nervous, and gastrointestinal systems. The purpose of this review is to build an extraordinarily specific method of histamine cycle assessment in regard to non-allergic intolerance and its possible dire consequences that can be suffered.

Neurotransmitter Dysfunction in Irritable Bowel Syndrome: Emerging Approaches for Management

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder whose aetiology is still unknown. Most hypotheses point out the gut-brain axis as a key factor for IBS. The axis is composed of different anatomic and functional structures intercommunicated through neurotransmitters. However, the implications of key neurotransmitters such as norepinephrine, serotonin, glutamate, GABA or acetylcholine in IBS are poorly studied. The aim of this review is to evaluate the current evidence about neurotransmitter dysfunction in IBS and explore the potential therapeutic approaches. IBS patients with altered colorectal motility show augmented norepinephrine and acetylcholine levels in plasma and an increased sensitivity of central serotonin receptors. A decrease of colonic mucosal serotonin transporter and a downregulation of α2 adrenoceptors are also correlated with visceral hypersensitivity and an increase of 5-hydroxyindole acetic acid levels, enhanced expression of high affinity choline transporter and lower levels of GABA. Given these neurotransmitter dysfunctions, novel pharmacological approaches such as 5-HT₃ receptor antagonists and 5-HT₄ receptor agonists are being explored for IBS management, for their antiemetic and prokinetic effects. GABA-analogous medications are being considered to reduce visceral pain. Moreover, agonists and antagonists of muscarinic receptors are under clinical trials. Targeting neurotransmitter dysfunction could provide promising new approaches for IBS management.

Glioplasticity in irritable bowel syndrome

BACKGROUND

Growing evidence indicates a wide array of cellular remodeling in the mucosal microenvironment during irritable bowel syndrome (IBS), which possibly contributes to pathophysiology and symptom generation. Here, we investigated whether enteric glial cells (EGC) may be altered, and which factors/mechanisms lead to these changes.

METHODS

Colonic mucosal biopsies of IBS patients (13 IBS-Constipation [IBS-C]; 10 IBS-Diarrhea [IBS-D]; 11 IBS-Mixed [IBS-M]) and 24 healthy controls (HC) were analyzed. Expression of S100β and GFAP was measured. Cultured rat EGC were incubated with supernatants from mucosal biopsies, then proliferation and Ca²⁺ response to ATP were analyzed using flow cytometry and Ca²⁺ imaging. Histamine and histamine 1-receptor (H1R) involvement in the effects of supernatant upon EGC was analyzed.

KEY RESULTS

Compared to HC, the mucosal area immunoreactive for S100β was significantly reduced in biopsies of IBS patients, independently of the IBS subtype. IBS-C supernatants reduced EGC proliferation and IBS-D and IBS-M supernatants reduced Ca²⁺ response to ATP in EGC. EGC expressed H1R and the effects of supernatant upon Ca²⁺ response to ATP in EGC were blocked by pyrilamine and reproduced by histamine via H1R. IBS supernatants reduced mRNA expression of connexin-43. The S100β-stained area was negatively correlated with the frequency and intensity of pain and bloating.

CONCLUSION AND INFERENCES

Changes in EGC occur in IBS, involving mucosal soluble factors. Histamine, via activation of H1R-dependent pathways, partly mediates altered Ca²⁺ response to ATP in EGC. These changes may contribute to the pathophysiology and the perception of pain and bloating in patients with IBS.

Evidence-based clinical practice guidelines for irritable bowel syndrome

New strategies for the care of irritable bowel syndrome (IBS) are developing and several novel treatments have been globally produced. New methods of care should be customized geographically because each country has a specific medical system, life style, eating habit, gut microbiota, genes and so on. Several clinical guidelines for IBS have been proposed and the Japanese Society of Gastroenterology (JSGE) subsequently developed evidence-based clinical practice guidelines for IBS. Sixty-two clinical questions (CQs) comprising 1 definition, 6 epidemiology, 6 pathophysiology, 10 diagnosis, 30 treatment, 4 prognosis, and 5 complications were proposed and statements were made to answer to CQs. A diagnosis algorithm and a three-step treatment was provided for patients with chronic abdominal pain or abdominal discomfort and/or abnormal bowel movement. If more than one alarm symptom/sign, risk factor and/or routine examination is positive, colonoscopy is indicated. If all of them, or the subsequent colonoscopy, are/is negative, Rome III or compatible criteria is applied. After IBS diagnosis, step 1 therapy consisting of diet therapy, behavioral modification and gut-targeted pharmacotherapy is indicated for four weeks. Non-responders to step 1 therapy proceed to the second step that includes psychopharmacological agents and simple psychotherapy for four weeks. In the third step, for patients non-responsive to step 2 therapy, a combination of gut-targeted pharmacotherapy, psychopharmacological treatments and/or specific psychotherapy is/are indicated. Clinical guidelines and consensus for IBS treatment in Japan are well suited for Japanese IBS patients; as such, they may provide useful insight for IBS treatment in other countries around the world.

Current and emerging pharmacotherapeutic options for irritable bowel syndrome

Treatment of irritable bowel syndrome (IBS) is challenging for both primary care physicians and gastroenterologists because of the heterogeneity of the patient population and the multifactorial pathophysiologies responsible for the symptoms in IBS. This review focuses on the current and emerging pharmacological treatments for IBS. Many of the current medications used to treat this disorder have distinct properties such as efficacy for different symptoms, safety profiles, contraindications, costs, dosing regimens, treatment duration and long-term data. All of these factors, in addition to patient preference and cognitive, food and environmental triggers, must be considered prior to any medication selection. This review will focus on randomized controlled trials with a general uniformity in study design, a rigorous patient selection and appropriate treatment durations. We will also discuss other exciting emerging treatments for IBS such as the µ-opioid receptor (agonists and antagonists), selective κ-opioid receptor agonists, anti-inflammatory drugs, serotonergic agents, bile acid modulators and intestinal bile acid transporters, which may prove promising in treating our patients.

The effect of Korean hand acupuncture on young, single Korean students with irritable bowel syndrome

The purpose of this study was to test the effectiveness of Korean hand acupuncture (KHA) on bowel symptoms, stress, mental health, and heart rate variability in women with irritable bowel syndrome. From a total sample of 42 women with irritable bowel syndrome diagnosed with Rome III, 21 were randomly selected to be given KHA, whereas 21 were given sham KHA. The KHA group received KHA on 16 spots related to bowel symptoms, whereas the sham KHA group received treatment to areas unrelated to bowel symptoms. KHA needles were applied for 25 minutes, twice a week, for 4 weeks. After the treatment, bowel symptoms were measured using a Bowel Symptom Severity Scale, stress using a global assessment of recent health, mental health using the Symptom Checklist-90-Revised, and heart rate variability. SAS 9.1 (SAS Institute, Cary, NC) was used to analyze the data, and a chi-square test, t test, and paired t test were used for analysis. The KHA group had a decrease in symptoms such as loose stool, bloating, abdominal discomfort, and abdominal pain compared with the sham KHA group (p < .05). However, there were no significant effects on stress, mental health, and heart rate variability. KHA was effective for bowel symptoms such as loose stool, bloating, abdominal discomfort, and abdominal pain, and it could be applied to patients with irritable bowel syndrome. There is a need for further research on the effectiveness of KHA in women with irritable bowel syndrome using more diverse physiological indexes.

Rifaximin therapy of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder characterized by abdominal pain and altered bowel habits in the absence of specific organic pathology. Although the underlying pathogenesis of IBS is not well-understood, small intestinal bacterial overgrowth (SIBO) or other abnormalities in the gut flora is believed to contribute to the development of a subset of IBS cases. Rifaximin is a poorly absorbed antimicrobial with activity against enteric pathogens. A number of studies have shown a significant improvement in IBS symptoms with antibiotic therapy including rifaximin. In this review, we discuss the pharmacokinetics, in vitro susceptibility profile, and efficacy and safety data from clinical trials of rifaximin treatment of IBS.

Enhanced auditory brainstem response and parental bonding style in children with gastrointestinal symptoms

BACKGROUND

The electrophysiological properties of the brain and influence of parental bonding in childhood irritable bowel syndrome (IBS) are unclear. We hypothesized that children with chronic gastrointestinal (GI) symptoms like IBS may show exaggerated brainstem auditory evoked potential (BAEP) responses and receive more inadequate parental bonding.

METHODOLOGY/PRINCIPAL FINDINGS

Children aged seven and their mothers (141 pairs) participated. BAEP was measured by summation of 1,000 waves of the electroencephalogram triggered by 75 dB click sounds. The mothers completed their Children's Somatization Inventory (CSI) and Parental Bonding Instrument (PBI). CSI results revealed 66 (42%) children without GI symptoms (controls) and 75 (58%) children with one or more GI symptoms (GI group). The III wave in the GI group (median 4.10 interquartile range [3.95-4.24] ms right, 4.04 [3.90-4.18] ms left) had a significantly shorter peak latency than controls (4.18 [4.06-4.34] ms right, p = 0.032, 4.13 [4.02-4.24] ms left, p = 0.018). The female GI group showed a significantly shorter peak latency of the III wave (4.00 [3.90-4.18] ms) than controls (4.18 [3.97-4.31] ms, p = 0.034) in the right side. BAEP in the male GI group did not significantly differ from that in controls. GI scores showed a significant correlation with the peak latency of the III wave in the left side (rho = -0.192, p = 0.025). The maternal care PBI scores in the GI group (29 [26]-[33]) were significantly lower than controls (31 [28.5-33], p = 0.010), while the maternal over-protection PBI scores were significantly higher in the GI group (16 [12]-[17]) than controls (13 [10.5-16], p = 0.024). Multiple regression analysis in females also supported these findings.

CONCLUSIONS

It is suggested that children with chronic GI symptoms have exaggerated brainstem responses to environmental stimuli and inadequate parental behaviors aggravate these symptoms.

Biopsychosocial model of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common chronic disorder seen in gastroenterology and primary care practice. It is characterized by recurrent abdominal pain or discomfort associated with disturbed bowel function. It is a heterogeneous disorder with varying treatments, and in this regard physicians sometimes struggle with finding the optimal approach to management of patients with IBS. This disorder induces high health care costs and variably reduces health-related quality of life. IBS is in the class of functional gastrointestinal disorders, and results from dysregulation of central and enteric nervous system interactions. Psychosocial factors are closely related to their gut physiology, associated cognitions, symptom manifestations and illness behavior. Therefore, it is important for the physician to recognize the psychosocial issues of patients with IBS and in addition to build a good patient-physician relationship in order to optimize treatment. This review focuses on the interaction between psychological and physiological factors associated with IBS by using a biopsychosocial model. In this article, we describe (1) the predisposing psychological features seen in early life; (2) the psychological factors associated with life stress, the symptom presentation, and their associated coping patterns; (3) gut pathophysiology with emphasis on disturbances in motility, visceral hypersensitivity and brain-gut interactions; and finally (4) the clinical outcomes and effective treatments including psychotherapeutic methods.

Biopsychosocial model of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common chronic disorder seen in gastroenterology and primary care practice. It is characterized by recurrent abdominal pain or discomfort associated with disturbed bowel function. It is a heterogeneous disorder with varying treatments, and in this regard physicians sometimes struggle with finding the optimal approach to management of patients with IBS. This disorder induces high health care costs and variably reduces health-related quality of life. IBS is in the class of functional gastrointestinal disorders, and results from dysregulation of central and enteric nervous system interactions. Psychosocial factors are closely related to their gut physiology, associated cognitions, symptom manifestations and illness behavior. Therefore, it is important for the physician to recognize the psychosocial issues of patients with IBS and in addition to build a good patient-physician relationship in order to optimize treatment. This review focuses on the interaction between psychological and physiological factors associated with IBS by using a biopsychosocial model. In this article, we describe (1) the predisposing psychological features seen in early life; (2) the psychological factors associated with life stress, the symptom presentation, and their associated coping patterns; (3) gut pathophysiology with emphasis on disturbances in motility, visceral hypersensitivity and brain-gut interactions; and finally (4) the clinical outcomes and effective treatments including psychotherapeutic methods.