Impact of sex and gender on irritable bowel syndrome

The Role of Estrogen across Multiple Disease Mechanisms

Estrogen is a significant hormone that is involved in a multitude of physiological and pathological processes. In addition to its pivotal role in the reproductive system, estrogen is also implicated in the pathogenesis of a multitude of diseases. Nevertheless, previous research on the role of estrogen in a multitude of diseases, including Alzheimer's disease, depression, cardiovascular disease, diabetes, osteoporosis, gastrointestinal diseases, and estrogen-dependent cancers, has concentrated on a single disease area, resulting in a lack of comprehensive understanding of cross-disease mechanisms. This has brought some challenges to the current treatment methods for these diseases, because estrogen as a potential therapeutic tool has not yet fully developed its potential. Therefore, this review aims to comprehensively explore the mechanism of estrogen in these seven types of diseases. The objective of this study is to describe the relationship between each disease and estrogen, including the ways in which estrogen participates in regulating disease mechanisms, and to outline the efficacy of estrogen in treating these diseases in clinical practice. By studying the role of estrogen in a variety of disease mechanisms, it is hoped that a more accurate theoretical basis and clinical guidance for future treatment strategies will be provided, thus promoting the effective management and treatment of these diseases.

Sexually Dimorphic Effects of Histamine Degradation by Enteric Glial Histamine N-Methyltransferase (HNMT) on Visceral Hypersensitivity

Histamine is a neuromodulator that affects gut motility and visceral sensitivity through intrinsic and extrinsic neural pathways, yet the mechanisms regulating histamine availability in these pathways remain poorly understood. Here, we show that enteric glia contribute to histamine clearance in the enteric nervous system (ENS) through their expression of the enzyme histamine N-methyltransferase (HNMT). Glial HNMT expression was initially assessed using immunolabeling and gene expression, and functionally tested using CRISPR-Cas9 to create a Cre-dependent conditional Hnmt ablation model targeting glia. Immunolabeling, calcium imaging, and visceromotor reflex recordings were used to assess the effects on ENS structure and visceral hypersensitivity. Immunolabeling and gene expression data show that enteric neurons and glia express HNMT. Deleting Hnmt in Sox10+ enteric glia increased glial histamine levels and altered visceromotor responses to colorectal distension in male mice, with no effect in females. Interestingly, deleting glial Hnmt protected males from histamine-driven visceral hypersensitivity. These data uncover a significant role for glial HNMT in histamine degradation in the gut, which impacts histamine-driven visceral hypersensitivity in a sex-dependent manner. Changes in the capacity of glia to clear histamines could play a role in the susceptibility to developing visceral pain in disorders of the gut-brain interaction.

Sex steroid metabolism and action in colon health and disease

The colon is the largest hormonally active tissue in the human body. It has been known for over a hundred years that various hormones and bioactive peptides play important roles in colon function. More recently there is a growing interest in the role the sex steroids, oestrogens and androgens, may play in both normal colon physiology and colon pathophysiology. In this review, we examine the potential role oestrogens and androgens play in the colon. The metabolism and subsequent action of sex steroids in colonic tissue is discussed and how these hormones impact colon motility is investigated. Furthermore, we also determine how oestrogens and androgens influence colorectal cancer incidence and development and highlight potential new therapeutic targets for this malignancy. This review also examines how sex steroids potentially impact the severity and progression of other colon disease, such as diverticulitis, irritable bowel syndrome, and polyp formation.

Sex- and gender-related differences in the prevalence and burden of disorders of gut-brain interaction in Poland

BACKGROUND

The aim of the study was to assess sex- and gender-related differences in the epidemiology and impact of disorders of gut-brain interaction (DGBI) in Poland.

METHODS

Data used for the current analysis were derived from the Polish population sample of 2057 subjects (1030 F, 1027 M) collected via the Internet survey that included the Rome IV diagnostic questionnaire and 80 supplementary questions.

KEY RESULTS

The overall prevalence of DGBI in Poland was 46.0% (51.7% in women and 40.3% in men, p < 0.001). Comparing women versus men, esophageal disorders were observed in 6.3% vs. 6.0%, respectively (p > 0.05), gastroduodenal disorders in 14.0% vs. 7.8% (p < 0.001), bowel disorders in 44.3% vs. 33.9% (p < 0.001), and anorectal disorders in 9.9% vs. 7.7% (p > 0.05). The six most common DGBI included functional constipation 14.2%, functional dyspepsia 8.3%, proctalgia fugax 6.6%, functional bloating 4.8%, functional diarrhea 4.5%, and irritable bowel syndrome (IBS) 4.4%. All these disorders, except for functional diarrhea, were more common in women. The DGBI overlap was significantly higher in women than in men (16.7% vs. 11.2%, p < 0.001). A higher number of overlapping DGBI correlated positively with IBS severity, higher level of somatization, anxiety and depression, poorer quality of life (QoL), and increased healthcare utilization.

CONCLUSIONS AND INFERENCES

This is the first comprehensive report on significant sex/gender-related differences in the prevalence and burden of DGBI in Poland. The revealed differences between women and men with DGBI in the clinical profile, psychosocial variables, and healthcare utilization may have important diagnostic and therapeutic implications.

A multi-omic brain gut microbiome signature differs between IBS subjects with different bowel habits

Alterations of the brain-gut-microbiome system (BGM) have been implicated in the pathophysiology of irritable bowel syndrome (IBS), yet bowel habit-specific alterations have not been elucidated. In this cross-sectional study, we apply a systems biology approach to characterize BGM patterns related to predominant bowel habit. Fecal samples and resting state fMRI were obtained from 102 premenopausal women (36 constipation-predominant IBS (IBS-C), 27 diarrhea-predominant IBS (IBS-D), 39 healthy controls (HCs)). Data integration analysis using latent components (DIABLO) was used to integrate data from the phenome, microbiome, metabolome, and resting-state connectome to predict HCs vs IBS-C vs IBS-D. Bloating and visceral sensitivity, distinguishing IBS from HC, were negatively associated with beneficial microbes and connectivity involving the orbitofrontal cortex. This suggests that gut interactions may generate aberrant central autonomic and descending pain pathways in IBS. The connection between IBS symptom duration, key microbes, and caudate connectivity may provide mechanistic insight to the chronicity of pain in IBS. Compared to IBS-C and HCs, IBS-D had higher levels of many key metabolites including tryptophan and phenylalanine, and increased connectivity between the sensorimotor and default mode networks; thus, suggestingan influence on diarrhea, self-related thoughts, and pain perception in IBS-D ('bottom-up' mechanism). IBS-C's microbiome and metabolome resembled HCs, but IBS-C had increased connectivity in the default mode and salience networks compared to IBS-D, which may indicate importance of visceral signals, suggesting a more 'top-down' BGM pathophysiology. These BGM characteristics highlight possible mechanistic differences for variations in the IBS bowel habit phenome. This article is part of the Special Issue on 'Microbiome & the Brain: Mechanisms & Maladies'.

Targeting the endocannabinoid system for the treatment of abdominal pain in irritable bowel syndrome

The management of visceral pain in patients with disorders of gut-brain interaction, notably irritable bowel syndrome, presents a considerable clinical challenge, with few available treatment options. Patients are increasingly using cannabis and cannabinoids to control abdominal pain. Cannabis acts on receptors of the endocannabinoid system, an endogenous system of lipid mediators that regulates gastrointestinal function and pain processing pathways in health and disease. The endocannabinoid system represents a logical molecular therapeutic target for the treatment of pain in irritable bowel syndrome. Here, we review the physiological and pathophysiological functions of the endocannabinoid system with a focus on the peripheral and central regulation of gastrointestinal function and visceral nociception. We address the use of cannabinoids in pain management, comparing them to other treatment modalities, including opioids and neuromodulators. Finally, we discuss emerging therapeutic candidates targeting the endocannabinoid system for the treatment of pain in irritable bowel syndrome.

Genetics of irritable bowel syndrome: shifting gear via biobank-scale studies

The pathophysiology of irritable bowel syndrome (IBS) is multifactorial and probably involves genetic predisposition and the effect of environmental factors. Unlike other gastrointestinal diseases with a heritable component, genetic research in IBS has been scarce and mostly characterized by small underpowered studies, leading to inconclusive results. The availability of genomic and health-related data from large international cohorts and population-based biobanks offers unprecedented opportunities for long-awaited, well-powered genetic studies in IBS. This Review focuses on the latest advances that provide compelling evidence for the importance of genes involved in the digestion of carbohydrates, ion channel function, neurotransmitters and their receptors, neuronal pathways and the control of gut motility. These discoveries have generated novel information that might be further refined for the identification of predisposed individuals and selection of management strategies for patients. This Review presents a conceptual framework, the advantages and potential limitations of modern genetic research in IBS, and a summary of available evidence.

Psychosocial and Sensory Factors Contribute to Self-Reported Pain and Quality of Life in Young Adults with Irritable Bowel Syndrome

AIMS

Psychosocial and sensory factors, including anxiety, depression, and pressure pain threshold have been used to cluster chronic symptoms in irritable bowel syndrome (IBS). This study examined the contribution of psychosocial sensory factors on pain interference and quality of life (QOL) in this population.

DESIGN

We performed a cross-sectional analysis of baseline data from a randomized controlled trial.

SETTINGS

Two gastrointestinal clinics, general communities, and two large campuses of a public university in the Northeastern United States.

PARTICIPANTS/SUBJECTS

Eighty young adults with IBS aged 21 ± 2.57 years (76.25% female).

METHODS

Demographic and psychosocial factors including anxiety, depression, fatigue, cognition or general concerns, sleep disturbance, self-efficacy, coping, and food intake were measured as independent variables. Quantitative sensory testing was conducted to measure mechanical, thermal, and pressure pain thresholds. Self-reported pain measured by the brief pain inventory (BPI) and IBS-QOL were assessed as the outcome variables. Regression analysis and mediation analysis were conducted to determine the associated factors of IBS pain and QOL.

RESULTS

Age, sex, and psychosocial factors including coping, self-efficacy, alcohol intake, mechanical pain sensitivity, and cold pain threshold were significantly associated with pain interference (all p < 0.05). Coping, and self-efficacy were significantly associated with IBS-QOL (all p < 0.05). In the mediation analysis, coping catastrophizing and self-efficacy were indirectly associated with IBS-QOL mediated by fatigue.

CONCLUSIONS

Psychosocial factors including coping and self-efficacy, and quantitative sensory testing factors significantly correlate with self-reported pain and QOL among young adults with IBS. This preliminary research calls for further interventional studies that target personalized psychosocial and quantitative sensory factors to improve pain management and quality of life in IBS patients.

Inter-hemispheric Functional Connections Are More Vulnerable to Attack Than Structural Connection in Patients With Irritable Bowel Syndrome

Background/Aims

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disease characterized by recurrent abdominal pain and bowel dysfunction. However, the majority of previous neuroimaging studies focus on brain structure and connections but seldom on the inter-hemispheric connectivity or structural asymmetry. This study uses multi-modal imaging to investigate the abnormal changes across the 2 cerebral hemispheres in patients with IBS.

Methods

Structural MRI, resting-state functional MRI, and diffusion tensor imaging were acquired from 34 patients with IBS and 33 healthy controls. The voxel-mirrored homotopic connectivity, fractional anisotropy, fiber length, fiber number, and asymmetry index were calculated and assessed for group differences. In addition, we assessed their relevance for the severity of IBS.

Results

Compared with healthy controls, the inter-hemispheric functional connectivity of patients with IBS showed higher levels in bilateral superior occipital gyrus, middle occipital gyrus, precuneus, posterior cingulate gyrus, and angular gyrus, but lower in supplementary motor area. The statistical results showed no significant difference in inter-hemispheric anatomical connections and structural asymmetry, however negative correlations between inter-hemispheric connectivity and the severity of IBS were found in some regions with significant difference.

Conclusions

The functional connections between cerebral hemispheres were more susceptible to IBS than anatomical connections, and brain structure is relatively stable. Besides, the brain areas affected by IBS were concentrated in default mode network and sensorimotor network.

Sex- and Gender-Related Differences in Common Functional Gastroenterologic Disorders

Functional gastrointestinal (GI) disorders (FGIDs) result from central and peripheral mechanisms, cause chronic remitting-relapsing symptoms, and are associated with comorbid conditions and impaired quality of life. This article reviews sex- and gender-based differences in the prevalence, pathophysiologic factors, clinical characteristics, and management of functional dyspepsia (FD) and irritable bowel syndrome (IBS) that together affect approximately 1 in 4 people in the United States. These conditions are more common in women. Among patients with IBS, women are more likely to have severe symptoms and coexistent anxiety or depression; constipation or bloating and diarrhea are more common in women and men, respectively, perhaps partly because defecatory disorders, which cause constipation, are more common in women. Current concepts suggest that biological disturbances (eg, persistent mucosal inflammation after acute gastroenteritis) interact with other environmental factors (eg, abuse) and psychological stressors, which influence the brain and gut to alter GI tract motility or sensation, thereby causing symptoms. By comparison to a considerable understanding of sex-based differences in the pathogenesis of visceral hypersensitivity in animal models, we know less about the contribution of these differences to FGID in humans. Slow gastric emptying and colon transit are more common in healthy women than in men, but effects of gonadal hormones on colon transit are less important than in rodents. Although increased visceral sensation partly explains symptoms, the effects of sex on visceral sensation, colonic permeability, and the gut microbiome are less prominent in humans than rodents. Whether sex or gender affects response to medications or behavioral therapy in FD or IBS is unclear because most patients in these studies are women.

Glial and neuroimmune cell choreography in sexually dimorphic pain signaling

Chronic pain is a major global health issue that affects all populations regardless of sex, age, ethnicity/race, or country of origin, leading to persistent physical and emotional distress and to the loss of patients' autonomy and quality of life. Despite tremendous efforts in the elucidation of the mechanisms contributing to the pathogenesis of chronic pain, the identification of new potential pain targets, and the development of novel analgesics, the pharmacological treatment options available for pain management remain limited, and most novel pain medications have failed to achieve advanced clinical development, leaving many patients with unbearable and undermanaged pain. Sex-specific susceptibility to chronic pain conditions as well as sex differences in pain sensitivity, pain tolerance and analgesic efficacy are increasingly recognized in the literature and have thus prompted scientists to seek mechanistic explanations. Hence, recent findings have highlighted that the signaling mechanisms underlying pain hypersensitivity are sexually dimorphic, which sheds light on the importance of conducting preclinical and clinical pain research on both sexes and of developing sex-specific pain medications. This review thus focuses on the clinical and preclinical evidence supporting the existence of sex differences in pain neurobiology. Attention is drawn to the sexually dimorphic role of glial and immune cells, which are both recognized as key players in neuroglial maladaptive plasticity at the origin of the transition from acute pain to chronic pathological pain. Growing evidence notably attributes to microglial cells a pivotal role in the sexually dimorphic pain phenotype and in the sexually dimorphic analgesic efficacy of opioids. This review also summarizes the recent advances in understanding the pathobiology underpinning the development of pain hypersensitivity in both males and females in different types of pain conditions, with particular emphasis on the mechanistic signaling pathways driving sexually dimorphic pain responses.

The impact of irritable bowel syndrome on health-related quality of life in women with polycystic ovary syndrome

BACKGROUND

The objectives of this study were to compare the prevalence and quality of life (QOL) of irritable bowel syndrome (IBS) in women with polycystic ovary syndrome (PCOS) compared with healthy women.

METHODS

This was a case-control study of 201 women recruited at an infertility clinic in Iran. The control group were healthy women (n = 100) and the comparison group, women with PCOS (n = 101). Data were collected by clinical Rome III criteria to determine the IBS, Bristol scale for stool consistency and IBS QOL.

RESULTS

The reporting of IBS symptoms were higher in PCOS (20.7%) than control group (11%) (P = 0.05). The IBS QOL score in the IBS + PCOS group was lower than other groups (IBS+ non PCOS, non IBS + PCOS, non IBS+ non PCOS; scores in food avoidance and worries about health domains were significant (P < 0.01).

CONCLUSIONS

We conclude that having PCOS and an increased level of LH/FSH tends to cause IBS symptoms. IBS + PCOS women experience significant impaired quality of life scores particularly in relation to worries about health and food avoidance. These results offer further insights into IBS in PCOS women and their functional status and wellbeing.

Sex as a biological variable in irritable bowel syndrome

BACKGROUND

The pathophysiology and mechanisms of irritable bowel syndrome (IBS) involve both central and peripheral mechanisms that result in altered perception, as well as changes in bowel functions. These dysfunctions are associated with motor, sensory, immune, barrier, and intraluminal perturbations, including the microbiota, and their products and endogenous molecules with bioactive properties. There is evidence that these mechanisms are altered in both females and males. However, there is also increasing evidence that sex is a biological variable that impacts a number of aspects of the mechanisms, epidemiology, and manifestations of IBS.

PURPOSE

The objective of this article is to review the evidence of the differences among genders of the following factors in IBS: the brain-gut axis and sex hormones, epidemiology, diagnostic criteria and prognosis, pain perception, colonic transit, abdominal distension, overlap with urogynecological conditions, psychologic issues, anorexia, fibromyalgia, serotonin, and responsiveness to treatment of IBS. It is important to consider the variations attributable to sex in order to enhance the management of patients with IBS and the research of mechanisms involved in IBS.

Tenapanor for the treatment of irritable bowel syndrome with constipation

INTRODUCTION

Irritable bowel syndrome with constipation is associated with higher rates of functional impairment, as compared to other subtypes of the syndrome. Conventional laxative-based pharmacologic therapy of IBS-C, which is mostly symptom-based, is often unsatisfactory. Tenapanor represents a first-in-class orally available inhibitor of NHE3, which is minimally absorbed in the GI tract, what constitutes a significant therapeutic benefit, as it may act on the drug target.

AREAS COVERED

Aim of this article is to sum up the evidences about pharmacodynamics and pharmacokinetics of tenapanor, focusing on animal models and in vitro studies, but also discuss clinical trials on tenapanor's safety and efficacy in view of its important potential role in IBS-C treatment.

EXPERT OPINION

In the challenging setting of irritable bowel syndrome with constipation, tenapanor represents a novel strategy in the pipeline of the therapies of IBS-C. Its pharmacokinetic and pharmacodynamic profile provides that it is minimally absorbed from the intestinal lumen and that its action is local, but not systemic action, therefore guaranteeing the reduction of drug-drug interactions, toxicity and severe adverse effects. Phase 2b and 3 trials showed an optimal satisfaction of primary and secondary endpoints.

Esophageal disorders in patients with irritable bowel syndrome

Aim.To study the whole range of esophageal disorders in patients with irritable bowel syndrome (IBS) using high-tech methods. Materials and methods.102 IBS patients (47 males, mean age 40.8, diagnosis of IBS was established according to Rome III criteria) with esophageal symptoms (heartburn, belching, globus sensation and noncardiac chest pain) were examined in gastroenterology department. All patients underwent endoscopy, with biopsies if required, X-ray examination of upper gastrointestinal tract; 24-hour pH-impedance monitoring;13C-urea breath test. Evaluation of esophageal symptoms was carried out on the basis of Rome IV criteria. Results.21 (20.6%) individuals had esophagitis (ERD). According to 24-hour pH-monitoring data, 7 of them had overlap between GERD and functional esophageal disorders (FED). 27 (26.5%) individuals had nonerosive reflux disease (NERD). In 54 (52.9%) individuals endoscopy and pH-impedance monitoring data did not differ from normal, suggesting this group as group of patients with FED. There was no significant difference for age, sex and IBS subtypes in GERD, NERD and FED groups. Conclusion.Comorbid esophageal disorders in patients with IBS are different and represented by organic diseases, FED and overlap between them. Methods such as 24-h pH-impedance measurement and esophageal manometry should be used to assess comorbid esophageal disorders in IBS patients.

Epigenetic Mechanisms in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a brain-gut axis disorder characterized by abdominal pain and altered bowel habits. IBS is a multifactorial, stress-sensitive disorder with evidence for familial clustering attributed to genetic or shared environmental factors. However, there are weak genetic associations reported with IBS and a lack of evidence to suggest that major genetic factor(s) contribute to IBS pathophysiology. Studies on animal models of stress, including early life stress, suggest a role for environmental factors, specifically, stress associated with dysregulation of corticotropin releasing factor and hypothalamus-pituitary-adrenal (HPA) axis pathways in the pathophysiology of IBS. Recent evidence suggests that epigenetic mechanisms, which constitute molecular changes not driven by a change in gene sequence, can mediate environmental effects on central and peripheral function. Epigenetic alterations including DNA methylation changes, histone modifications, and differential expression of non-coding RNAs (microRNA [miRNA] and long non-coding RNA) have been associated with several diseases. The objective of this review is to elucidate the molecular factors in the pathophysiology of IBS with an emphasis on epigenetic mechanisms. Emerging evidence for epigenetic changes in IBS includes changes in DNA methylation in animal models of IBS and patients with IBS, and various miRNAs that have been associated with IBS and endophenotypes, such as increased visceral sensitivity and intestinal permeability. DNA methylation, in particular, is an emerging field in the realm of complex diseases and a promising mechanism which can provide important insights into IBS pathogenesis and identify potential targets for treatment.

The roles of estrogen and estrogen receptors in gastrointestinal disease

Estrogen is an important sex steroid hormone which serves an important role in the regulation of a number of biological functions, including regulating bone density, brain function, cholesterol mobilization, electrolyte balance, skin physiology, the cardiovascular system, the central nervous system and female reproductive organs. Estrogen exhibits various functions through binding to its specific receptors, estrogen receptor α, estrogen receptor β and G protein-coupled estrogen receptor 1. In recent years, researchers have demonstrated that estrogen and its receptors serve an important role in the gastrointestinal (GI) tract and contribute to the progression of a number of GI diseases, including gastroesophageal reflux, esophageal cancer, peptic ulcers, gastric cancer, inflammatory bowel disease, irritable bowel syndrome and colon cancer. The aim of this review is to provide an overview of estrogen and its receptors in GI disease, and highlight potential avenues for the prevention and treatment of GI diseases.

Serotonin-estrogen interactions: What can we learn from pregnancy?

We have reviewed the scientific literature related to four diseases in which to serotonin (5-HT) is involved in the etiology, herein named 5-HT-linked diseases, and whose prevalence is influenced by estrogenic status: depression, migraine, irritable bowel syndrome and eating disorders. These diseases all have in common a sex-dimorphic prevalence, with women more frequently affected than men. The co-occurrence between these 5-HT-linked diseases suggests that they have common physiopathological mechanisms. In most 5-HT-linked diseases (except for anorexia nervosa and irritable bowel syndrome), a decrease in the serotonergic tone is observed and estrogens are thought to contribute to the improvement of symptoms by stimulating the serotonergic system. Human pregnancy is characterized by a unique 5-HT and estrogen synthesis by the placenta. Pregnancy-specific disorders, such as hyperemesis gravidarum, gestational diabetes mellitus and pre-eclampsia, are associated with a hyperserotonergic state and decreased estrogen levels. Fetal programming of 5-HT-linked diseases is a complex phenomenon that involves notably fetal-sex differences, which suggest the implication of sex steroids. From a mechanistic point of view, we hypothesize that estrogens regulate the serotonergic system, resulting in a protective effect against 5-HT-linked diseases, but that, in turn, 5-HT affects estrogen synthesis in an attempt to retrieve homeostasis. These two processes (5-HT and estrogen biosynthesis) are crucial for successful pregnancy outcomes, and thus, a disruption of this 5-HT-estrogen relationship may explain pregnancy-specific pathologies or pregnancy complications associated with 5-HT-linked diseases.

Female-Specific Association Between Variants on Chromosome 9 and Self-Reported Diagnosis of Irritable Bowel Syndrome

BACKGROUND & AIMS

Genetic factors are believed to affect risk for irritable bowel syndrome (IBS), but there have been no sufficiently powered and adequately sized studies. To identify DNA variants associated with IBS risk, we performed a genome-wide association study (GWAS) of the large UK Biobank population-based cohort, which includes genotype and health data from 500,000 participants.

METHODS

We studied 7,287,191 high-quality single nucleotide polymorphisms in individuals who self-reported a doctor's diagnosis of IBS (cases; n = 9576) compared to the remainder of the cohort (controls; n = 336,499) (mean age of study subjects, 40-69 years). Genome-wide significant findings were further investigated in 2045 patients with IBS from tertiary centers and 7955 population controls from Europe and the United States, and a small general population sample from Sweden (n = 249). Functional annotation of GWAS results was carried out by integrating data from multiple biorepositories to obtain biological insights from the observed associations.

RESULTS

We identified a genome-wide significant association on chromosome 9q31.2 (single nucleotide polymorphism rs10512344; P = 3.57 × 10-8) in a region previously linked to age at menarche, and 13 additional loci of suggestive significance (P < 5.0×10-6). Sex-stratified analyses revealed that the variants at 9q31.2 affect risk of IBS in women only (P = 4.29 × 10-10 in UK Biobank) and also associate with constipation-predominant IBS in women (P = .015 in the tertiary cohort) and harder stools in women (P = .0012 in the population-based sample). Functional annotation of the 9q31.2 locus identified 8 candidate genes, including the elongator complex protein 1 gene (ELP1 or IKBKAP), which is mutated in patients with familial dysautonomia.

CONCLUSIONS

In a sufficiently powered GWAS of IBS, we associated variants at the locus 9q31.2 with risk of IBS in women. This observation may provide additional rationale for investigating the role of sex hormones and autonomic dysfunction in IBS.

Oral contraceptive pills: Risky or protective in case of Trichinella spiralis infection?

The aim of this study was to investigate how Trichinella spiralis infection can be affected by contraceptive pills in vivo. Methods included six groups of female Wistar rats; healthy, Trichinella infected, receiving combined contraceptive pills (COCPs), receiving progestin only pills (POPs), infected receiving COCPs and infected receiving POPs. Parasite burden was measured; adult worm counts, gravidity, larvae and reproductive capacity index). Histopathological examination, immunohistochemical detection of C-kit+ mast cells and Foxp3+ T-reg. cells in intestinal sections, eosinophils muscle infiltration and CPK level were performed. Rats infected and receiving COCPs showed a significant increase in parasitic burden, and infected receiving POPs showed a significant reduction compared to infected only, with a significant increase in nongravid females (Mean total worms=964.40±55.9, 742±52.63, 686±31.68, larvae/g=5030±198.75, 2490±143.18 and 4126±152,91, respectively). Intestinal sections from infected receiving COCPs showed intact mucosa (though the high inflammatory cells infiltrate), and significant increase in C-kit+ mast cells number and intensity (30.20±4.15 and 60.40±8.29), and Foxp3+ T-reg. cells (10±1.58). Infected receiving POPs showed a significantly less CPK (5886±574.40) and eosinophilic muscle infiltration (58±13.51). Oestrogen-containing pills established a favourable intestinal environment for Trichinella by enhancing Foxp+T-reg. cells and stabilizing C-kit+mast cells, while POPs gave a potential protection with less gravidity, larval burden and eosinophilic infiltrate.

Sleep disturbances in irritable bowel syndrome: a systematic review

BACKGROUND

Sleep disturbances are well-documented among persons with irritable bowel syndrome (IBS). Difficulty in falling asleep, shorter sleep time, frequent arousal and awakenings, or non-restorative sleep are the most common manifestations. Sleep disturbances are also related to a higher risk of having IBS. Some researchers have provided evidence of a positive association between poorer subjective sleep quality and increased severity and frequency in gastrointestinal (GI) symptoms in those with IBS. However, findings from studies using objective sleep and activity measures, such as polysomnography and actigraphy, are inconclusive.

PURPOSE

This systematic review of the literature between 1990 and 2015 evaluates the evidence of sleep disturbances in adults with IBS and their relationship with GI symptoms.

Gender Differences in Serotonin Signaling in Patients with Diarrhea-predominant Irritable Bowel Syndrome

Objective Gender differences, including differences in the prevalence, subtypes and the effectiveness of treatment, are generally recognized in irritable bowel syndrome (IBS). Although serotonin type 3 receptor (5-HT3R) antagonists appear to be more effective in women with diarrhea predominant IBS (IBS-D) than they are in men, the mechanisms underlying these effects remain unclear. The aim of the present was to investigate the gender differences in 5-HT signaling. Methods The subjects were selected from outpatients with IBS-D and healthy controls. Their rectal mucosal S100A, tryptophan hydroxylase (TPH) and 5-HT transporter (5-HTT, SERT, SLC6A4) mRNA expression levels were measured. Clinical symptoms were evaluated using the gastrointestinal symptom rating scale (GSRS) and the self-rating depression scale (SDS). Results The study population of 100 subjects included 47 IBS-D patients and 53 age- and gender-matched healthy controls. The S100A9 (5.20 vs. 1.90, p=0.001) and SLC6A4 (2.00 vs. 1.00, p=0.019) mRNA levels in the rectal mucosa of women with IBS-D were significantly higher than those in men. Among the healthy controls, the S100A10 expression levels in men were higher than those in women (1.33 vs. 0.82, p=0.005). The S100A8 and S100A10 expression levels in women with IBS-D were positively correlated with their diarrhea scores (r=0.55 and 0.58, p<0.05). Conclusion 5-HT signaling might be a major contributor to the symptoms of IBS in men, and the differences may be associated with the effectiveness of 5-HT3R antagonists.

Gender influences on efficacy and safety of sublingual zolpidem tartrate for middle-of-the-night awakening in insomnia

OBJECTIVE

Evaluate potential gender effects on efficacy and safety of a buffered zolpidem sublingual tablet (ZST) formulation.

METHODS

Post hoc analysis of the pivotal sleep laboratory and outpatient studies, per gender.

RESULTS

In the sleep laboratory study, polysomnography-derived latency to persistent sleep after middle-of-the-night was significantly improved for both genders at both 1.75 mg and 3.5 mg ZST (females: 15.7 and 8.6 min, respectively, vs. 27.7 min [placebo]; males: 19.0 and 12.7 min vs. 29.0 min [placebo]) with no significant gender differences. In the outpatient study, subjective sleep onset latency after middle-of-the-night was significantly shorter for both genders treated with ZST 3.5 mg versus placebo over the 4-week average (females: 37.3 vs. 59.4 min, p < 0.0001; males: 38.6 vs. 55.1 min, p ≤ 0.01). There were no gender differences in subjective sleep onset latency after middle-of-the-night awakening. In the outpatient study, weekly usage of ZST and placebo by both genders declined throughout the study. Morning alertness following dosing nights improved in both genders, although significant only in females. In both studies, there were no gender differences in adverse events.

CONCLUSION(S)

Time to return to sleep after middle-of-the-night dosing with ZST improved in both genders, with no gender differences in efficacy and safety.

Comorbidities in patients with irritable bowel syndrome with constipation or chronic idiopathic constipation: a review of the literature from the past decade

BACKGROUND

Irritable bowel syndrome with constipation (IBS-C) and chronic idiopathic constipation (CIC) are common functional bowel disorders. Patients with IBS-C or CIC often present with ≥ 1 comorbidity that coincides with either of these conditions. These comorbidities may make underappreciated contributions to the patient's overall disease burden.

OBJECTIVE

To identify the comorbidities that are the most frequently reported in patients with IBS-C or CIC in the medical literature.

METHODS

A literature search (January 2001-March 2012) was performed using the Medline and Medline In-Process databases. Studies of adult patients with IBS-C or CIC were selected, and the prevalence rates of the comorbidities were extracted and analyzed according to the body system affected.

RESULTS

A total of 70 distinct comorbidities were identified from 35 published studies. These comorbidities involved several body systems, including the gastrointestinal, genitourinary, psychiatric, endocrine, and allergic or immunologic systems. Functional dyspepsia and depression were the most common comorbidities in patients with IBS-C, whereas functional dyspepsia, diabetes, and depression were the most common comorbidities in patients with CIC.

CONCLUSION

Patients with IBS-C or CIC frequently experience a wide range of comorbidities that contribute to their disease burden. Thus, we believe that medical professionals should consider common comorbidities when diagnosing and treating patients with IBS-C or CIC.

Treatment of irritable bowel syndrome: sex and gender specific aspects

Patients with functional gastrointestinal disorders constitute the majority of patients seeking healthcare for gastrointestinal symptoms in primary and secondary care. Of these disorders irritable bowel syndrome (IBS) is one of the most common and affects 10-20% in the Western world. IBS is a functional bowel disorder characterized by chronic abdominal pain, discomfort, bloating, and alteration of bowel habits in the absence of any detectable organic cause. Sex and gender aspects are important in understanding differences between men and women in their risk and experience of IBS. Relative to men, women are diagnosed more frequently with IBS. Female patients are more likely to be constipated, complain of abdominal distension and of certain extracolonic symptoms. Given the variability of IBS, the most successful treatment will be comprehensive, involving multiple strategies. Efficacy, safety and tolerability are important in the evaluation of IBS therapies, as patients are likely to require long-term treatment. Laxatives, antidiarrheals or antispasmodics are common in the treatment of IBS but the majority of patients receive antispasmodics followed by prokinetic agents. In treatment of IBS there appears to be a greater clinical response to serotonergic agents developed for IBS in women compared to men. There is an absence of drugs licensed specifically for the treatment of IBS. Further studies with novel agents are needed, to evaluate new approaches to IBS management including gender specific behavioral therapies and better characterization of patient subgroups with regard to drug therapy so that personalized therapy can be tested.

Sex differences in spinal processing of transient and inflammatory colorectal stimuli in the rat

Sex differences in the spinal processing of somatic and visceral stimuli contribute to greater female sensitivity in many pain disorders. The present study examined spinal mechanisms that contribute to sex differences in visceral sensitivity. The visceromotor response to colorectal distention (CRD) was more robust in normal female rats and after intracolonic mustard oil compared with that in male rats. No sex difference was observed in the CRD-evoked response of lumbosacral (LS) and thoracolumbar (TL) colonic afferents in normal and mustard oil-treated rats, but there was a sex difference in spontaneous activity that was exacerbated by intracolonic mustard oil. The response of visceroceptive dorsal horn neurons to CRD was greater in normal female rats in the LS and TL spinal segments. The effect of intracolonic mustard oil on the CRD-evoked response of different phenotypes of visceroceptive dorsal horn neurons was dependent on sex and segment. The NMDA receptor antagonist 2-amino-5-phosphonopentanoic acid (APV) dose-dependently attenuated the visceromotor response in normal rats with greater effect in male rats. Correspondingly, there was greater cell membrane expression of the GluN1 subunit in dorsal horn extracts in female rats. After intracolonic mustard oil, there was no longer a sex difference in the effect of APV nor GluN1 expression in LS segments, but greater female expression in TL segments. These data document a sex difference in spinal processing of nociceptive visceral stimuli from the normal and inflamed colon. Differences in dorsal horn neuronal activity and NMDA receptor expression contribute to the sex differences in the visceral sensitivity observed in awake rats.

Estrogen receptor β activation is antinociceptive in a model of visceral pain in the rat

The mechanism underlying estrogen modulation of visceral pain remains unclear. Our previous studies indicate that activation of estrogen receptor α (ERα) enhances visceral pain. The purpose of the present study was to investigate the role of estrogen receptor β (ERβ) activation in spinal processing of visceral stimuli. The effects of selective ERβ agonists on the visceromotor response (VMR) and dorsal horn neuronal responses to colorectal distention (CRD) were tested in ovariectomized and intact female rats. The magnitude of the VMR to CRD was significantly attenuated by ERβ agonists diarylpropionitrile (DPN) and WAY-200070 4 hours after subcutaneous injection. Pretreatment with the estrogen receptor antagonist ICI 182,780 obscured the DPN-evoked attenuation. There was no effect of DPN on the VMR at earlier time points. Subcutaneous and spinal administration of DPN attenuated the response of visceroceptive dorsal horn neurons with a comparable time course. DPN attenuated the VMR in intact rats regardless of estrous cycle stage. The time course of effect of ERβ activation on the visceromotor response and neuronal activity is consistent with transcriptional or translational modulation of neuronal activity.

PERSPECTIVE

Activation of ERβ is antinociceptive in the colorectal distention model of visceral pain, which may provide a therapeutic target to manage irritable bowel syndrome in the clinic.

The process of symptom control in Korean women with irritable bowel syndrome

Irritable bowel syndrome is chronic, uncontrollable, and unpredictable in nature. This study explored how Korean women with irritable bowel syndrome decipher the meaning of their symptoms and implement irritable bowel syndrome health management strategies. Data were collected in 2009 from 14 Korean women in their 20s and 30s through in-depth interviews using grounded theory. The constant comparative method was adopted for data analysis. The core category identified in the study was the "process of controlling irritable bowel syndrome symptoms." Strategies showed a temporal change progressing through stages of helplessness, searching, realization, struggling, and controlling. Early in symptom management, subjects tended to rely on medication or did not have a strategy. After a trial and error process, subjects did not use medication and natural symptom management that incorporated regular living habits, dietary control, and stress management. The introduction of strategic nursing interventions for irritable bowel syndrome based on the temporal stage of health management is recommended.

Frequency of irritable bowel syndrome, entrance examination-related stress, mental health, and quality of life in high school students

The purpose of this study was to examine entrance examination-related stress, mental health, and the quality of life of high school students with and without irritable bowel syndrome. We administered a descriptive survey by collecting data from 1,877 students from eight schools in Gyeonggi province, Korea. This study employed the Rome III criteria for the assessment of irritable bowel syndrome, an entrance examination stress scale for measuring entrance examination-related stress, the revised Symptom Checklist-90-Revised for measuring mental health, and the World Health Organization Quality of Life Scale Abbreviated Version for measuring the quality of life. The frequency of irritable bowel syndrome in students was 19.0%. A majority had a mixed constipation and diarrhea subtype of irritable bowel syndrome. Compared with the high school students without irritable bowel syndrome, those with irritable bowel syndrome reported a significantly higher score on the entrance examination stress scale, Symptom Checklist-90-Revised, and World Health Organization Quality of Life Scale Abbreviated Version. Results suggest support for creating a high school education program that provides knowledge and information about irritable bowel syndrome to students. Furthermore, it is important to explore suitable therapeutic approaches and nursing interventions for this population.

Effects of acute adult and early-in-life bladder inflammation on bladder neuropeptides in adult female rats

Background

The purpose of the present study was to determine how acute adult and/or prior early-in life (EIL; P14-P16) exposure to bladder inflammation affects bladder content of calcitonin gene related peptide (CGRP) and substance P (SP). Estrous cycle influences were also studied in the adult-treatment conditions.

Methods

In Experiment 1, intravesical zymosan or isoflurane anesthesia alone was administered to adult female rats. Bladders and serum were collected 24 hours later during each phase of the estrous cycle. In Experiment 2, zymosan or anesthesia alone was administered EIL and as adults, with bladder tissue collection 24 h later.

Results

In general, Experiment 1 showed that bladder content of both CGRP and SP was increased by inflammation. This effect was significant when data were collapsed across all phases of the estrous cycle, but was only significant during proestrus when individual comparisons were made during each phase of estrous. Also, adult bladder inflammation significantly reduced estradiol levels. In Experiment 2, bladder content of CGRP and SP was significantly increased in rats receiving EIL and/or adult inflammation. Bladder weights were also significantly increased by inflammation.

Conclusions

These data indicate that bladder CGRP and SP are maximally increased during the proestrus phase of the estrous cycle in inflamed adult female rats. EIL exposure to bladder inflammation alone can also produce an increase in CGRP and SP lasting into adulthood. Therefore, EIL experience with bladder inflammation may predispose an organism to experience a painful bladder disorder as an adult by increasing primary afferent content of CGRP and/or SP.

Sex steroids localized to the amygdala increase pain responses to visceral stimulation in rats

Females are disproportionately affected by irritable bowel syndrome (IBS) with menstrual cycle-dependent fluctuations in abdominal pain suggesting a role for ovarian hormones. IBS patients also exhibit greater activation of brain areas involved in pain affect such as the amygdala, yet the role of supraspinal processes in the effects of ovarian hormones on visceral pain is largely unexplored. The goal of the current study was to determine whether sex steroids act at the level of the amygdala to alter colonic pain sensitivity. Ovariectomized rats received implants on the amygdala of progesterone, estradiol, progesterone combined with estradiol, or cholesterol as a control to examine the involvement of the amygdala in ovarian hormone-mediated changes in visceral sensitivity. Visceral sensitivity was quantified as the number of abdominal contractions, a visceromotor response (VMR), in response to graded pressures of colorectal distension (CRD). Somatic sensitivity was also assessed by measuring the mechanical force required to elicit hindpaw withdrawal. Elevated levels of progesterone and/or estradiol on the amygdala heightened the responsiveness to CRD; in contrast, neither estradiol nor progesterone altered somatic sensation. Furthermore, administration of progesterone or estradiol to areas adjacent to the amygdala did not affect visceral sensitivity. Future studies will address the specific steroid receptors mediating the effects of progesterone and estradiol.

PERSPECTIVE

To our knowledge, this study represents the first description of a specific brain site mediating the effects of ovarian steroids on visceral sensitivity. These data also suggest that an amygdala-dependent mechanism may be responsible, at least in part, for the exacerbation of visceral symptomatology in females.

Sex-related differences in prepulse inhibition of startle in irritable bowel syndrome (IBS)

Alterations in central networks involved in the regulation of arousal, attention, and cognition may be critical for irritable bowel syndrome (IBS) symptom maintenance and exacerbation. Differential sensitivities in these networks may underlie sex differences noted in IBS. The current study examined prepulse inhibition (PPI), a measure of sensorimotor gating, in male and female IBS patients. Relationships between PPI and symptom severity were examined, as well as potential menstrual status effects. Compared to healthy controls, male IBS patients had significantly reduced PPI; whereas female IBS patients (particularly naturally cycling women) had significantly enhanced PPI suggesting hypervigilance. Considering previously demonstrated sex-related differences in perceptual and brain imaging findings in IBS patients, the current findings suggest that different neurobiological mechanisms underlie symptom presentation in male and female IBS patients. Compromised filtering of information in male IBS patients may be due to compromised top down (prefrontal, midcingulate) control mechanisms while increased attention to threat due to increased limbic and paralimbic circuits may be characteristic of female IBS patients.

Serotonin transporter activity and serotonin concentration in platelets of patients with irritable bowel syndrome: effect of gender

BACKGROUND

In the past decade, a strong argument has been built for the role of serotonin (5HT) and the serotonin transporter (SERT) in irritable bowel syndrome (IBS). However, it is still not clear how SERT contributes to this clinically heterogeneous disease. The present study addressed this issue by implementing platelet (plt) markers of SERT activity in the assessment protocol.

METHODS

Fasting blood samples of 149 (51 male/98 female) subjects with Rome II and III defined IBS subtypes, and 163 healthy control subjects (CSs; 75 male/88 female) were analyzed for platelet 5HT concentration and 5HT uptake activity [maximum uptake rate (V (max)) and affinity constant (K (m))].

RESULTS

Gender had a significant impact on platelet markers of SERT activity. Male IBS patients showed significantly lower median V (max) and K (m) values than the male CS (V (max) 1.706 vs. 2.148 nmol/10(9) plts x min, P < 0.001; K (m) 346 vs. 410 nmol, P = 0.008) without any significant reduction in platelet 5HT concentration (362 vs. 394 ng/10(9) plts). On the other hand, V (max) values were not different between female IBS patients and female CS (1.642 vs. 1.741 nmol/10(9) plts x min), but platelet 5HT concentration was significantly lower in females with diarrhea-predominant IBS (363 vs. 435 ng/10(9) plts, P < 0.05).

CONCLUSION

Although an absolute extrapolation from platelets to the gastrointestinal tissue does not appear to be justified, our findings demonstrated that the contribution of disturbed SERT activity to IBS is not uniform and is possibly gender-specific. The results suggest that an assessment of SERT function in platelets may help to elucidate the differences between IBS patients in response to drugs affecting the 5HT system.

Impact of oral bisphenol A at reference doses on intestinal barrier function and sex differences after perinatal exposure in rats

Bisphenol A (BPA), a chemical estrogen widely used in the food-packaging industry and baby bottles, is recovered in human fluids (0.1-10 nM). Recent studies have reported that BPA is hormonally active at low doses, emphasizing the debate of a risk for human health. Estrogen receptors are expressed in the colon, and although the major route of BPA exposure is food, the effects on gut have received no attention. We first examined the endocrine disrupting potency of BPA on colonic paracellular permeability (CPP), experimental colitis, and visceral sensitivity in ovariectomized rats orally exposed to 5 mg/kg/d BPA (i.e., the no observed adverse effect level), 50 microg/kg/d BPA (i.e., tolerable daily intake), or lower doses. BPA dose-dependently decreased basal CPP, with a half-maximal inhibitory dose of 5.2 microg/kg/d, 10-fold below the tolerable daily intake. This correlated with an increase in epithelial tight junction sealing, also observed in Caco-2 cells exposed to 10 nM BPA. When ovariectomized rats were fed with BPA at the no observed adverse effect level, the severity of colitis was reduced, whereas the same dose increased pain sensitivity to colorectal stimuli. We then examined the impact of perinatal exposure to BPA on intestinal permeability and inflammatory response in the offspring. In female rats, but not in male rats, perinatal BPA evoked a decrease of CPP in adulthood, whereas the proinflammatory response of colonic mucosa was strengthened. This study first demonstrates that the xenoestrogen BPA at reference doses influences intestinal barrier function and gut nociception. Moreover, perinatal exposure promotes the development of severe inflammation in adult female offspring only.

Estrogen and its role in gastrointestinal health and disease

INTRODUCTION

While the concept of a role of estrogen in gastrointestinal (in particular, colonic) malignancy has generated excitement in recent years, no review has examined the role of this potent and omnipresent steroid hormone in physiological states or its contribution to the development of benign pathological processes. Understanding these effects (and mechanisms therein) may provide a platform for a deeper understanding of more complex disease processes.

METHODS

A literature search was conducted using the PubMed database and the search terms were "estrogen," "estrogen AND gastrointestinal tract," "estrogen AND colon," "estrogen AND esophagus," "estrogen AND small intestine," "estrogen AND stomach," "estrogen AND gallbladder," and "estrogen AND motility." Bibliographies of extracted studies were further cross-referenced. In all, 136 full-text articles were selected for review. A logical organ-based approach was taken to enable extraction of data of clinical relevance and meaningful interpretation thereof. Insight is provided into the hypotheses, theories, controversies, and contradictions generated over the last five decades by extensive investigation of estrogen in human, animal, and cell models using techniques as diverse as autoradiographic studies of baboons to human population analysis.

CONCLUSIONS

Effects from esophagus through to the colon and rectum are summarized in this first concise collection of data pertaining to estrogenic actions in gastrointestinal health and disease. Mechanisms of these actions are discussed where possible. Undoubtedly, this hormone exerts many actions yet to be elucidated, and its potential therapeutic applications remain, as yet, largely unexplored.

Role of anxiety in the pathophysiology of irritable bowel syndrome: importance of the amygdala

A common characteristic of irritable bowel syndrome (IBS) is that symptoms, including abdominal pain and abnormal bowel habits, are often triggered or exacerbated during periods of stress and anxiety. However, the impact of anxiety and affective disorders on the gastrointestinal (GI) tract is poorly understood and may in part explain the lack of effective therapeutic approaches to treat IBS. The amygdala is an important structure for regulating anxiety with the central nucleus of the amygdala facilitating the activation of the hypothalamic-pituitary-adrenal axis and the autonomic nervous system in response to stress. Moreover, chronic stress enhances function of the amygdala and promotes neural plasticity throughout the amygdaloid complex. This review outlines the latest findings obtained from human studies and animal models related to the role of the emotional brain in the regulation of enteric function, specifically how increasing the gain of the amygdala to induce anxiety-like behavior using corticosterone or chronic stress increases responsiveness to both visceral and somatic stimuli in rodents. A focus of the review is the relative importance of mineralocorticoid receptor and glucocorticoid receptor-mediated mechanisms within the amygdala in the regulation of anxiety and nociceptive behaviors that are characteristic features of IBS. This review also discusses several outstanding questions important for future research on the role of the amygdala in the generation of abnormal GI function that may lead to potential targets for new therapies to treat functional bowel disorders such as IBS.

From Hans Selye's discovery of biological stress to the identification of corticotropin-releasing factor signaling pathways: implication in stress-related functional bowel diseases

Selye pioneered the concept of biological stress in 1936, culminating in the identification of the corticotropin-releasing factor (CRF) signaling pathways by Vale's group in the last two decades. The characterization of the 41 amino-acid CRF and other peptide members of the mammalian CRF family, urocortin 1, urocortin 2, and urocortin 3, and the cloning of CRF(1) and CRF(2) receptors, which display distinct affinity for CRF ligands, combined with the development of selective CRF receptor antagonists enable us to unravel the importance of CRF(1) receptor in the stress-related endocrine (activation of pituitary-adrenal axis), behavioral (anxiety/depression, altered feeding), autonomic (activation of sympathetic nervous system), and immune responses. The activation of CRF(1) receptors is also one of the key mechanisms through which various stressors impact the gut to stimulate colonic propulsive motor function and to induce hypersensitivity to colorectal distension as shown by the efficacy of the CRF(1) receptor antagonists in blunting these stress-related components. The importance of CRF(1) signaling pathway in the visceral response to stress in experimental animals provided new therapeutic approaches for treatment of functional bowel disorder such as irritable bowel syndrome, a multifactor functional disorder characterized by altered bowel habits and visceral pain, for which stress has been implicated in the pathophysiology and is associated with anxiety-depression in a subset of patients.

Is it all about sex? Acupuncture for the treatment of pain from a biological and gender perspective

Pain is a unique personal experience showing variability where gender and sex related effects might contribute. The mechanisms underlying the differences between women and men are currently unknown but are likely to be complex and involving interactions between biological, sociocultural and psychological aspects. In women, painful experimental stimuli are generally reported to produce a greater intensity of pain than in men. Clinical pain is often reported with higher severity and frequency, longer duration, and present in a greater number of body regions in women than in men. Women are also more likely to experience a number of painful conditions such as fibromyalgia, temporomandibular dysfunction, migraine, rheumatoid arthritis and irritable bowel syndrome. With regard to biological factors, quantitative as well as qualitative differences in the endogenous pain inhibitory systems have been implicated, as well as an influence of gonadal hormones. Psychosocial factors like sex role beliefs, pain coping strategies, and pain related expectancies may also contribute to the differences. Being exposed to repeated painful visceral events (eg menses, labour) during life may contribute to an increased sensitivity to, and greater prevalence of, pain among women. When assessing the outcome of pharmacological and non-pharmacological therapies in pain treatment, the factors of gender and sex should be taken into account as the response to an intervention may differ. Preferably, treatment recommendations should be based on studies using both women and men as the norm. Due to variability in results, findings from animal studies and experiments in healthy subjects should be interpreted with care.

Sex differences in brain activity during aversive visceral stimulation and its expectation in patients with chronic abdominal pain: a network analysis

Differences in brain responses to aversive visceral stimuli may underlie previously reported sex differences in symptoms as well as perceptual and emotional responses to such stimuli in patients with irritable bowel syndrome (IBS). The goal of the current study was to identify brain networks activated by expected and delivered aversive visceral stimuli in male and female patients with chronic abdominal pain, and to test for sex differences in the effective connectivity of the circuitry comprising these networks. Network analysis was applied to assess the brain response of 46 IBS patients (22 men and 24 women) recorded using [15O] water positron emission tomography during rest/baseline and expected and delivered aversive rectal distension. Functional connectivity results from partial least squares analyses provided support for the hypothesized involvement of 3 networks corresponding to: 1) visceral afferent information processing (thalamus, insula and dorsal anterior cingulate cortex, orbital frontal cortex), 2) emotional-arousal (amygdala, rostral and subgenual cingulate regions, and locus coeruleus complex) and 3) cortical modulation (frontal and parietal cortices). Effective connectivity results obtained via structural equation modeling indicated that sex-related differences in brain response are largely due to alterations in the effective connectivity of emotional-arousal circuitry rather than visceral afferent processing circuits. Sex differences in the cortico-limbic circuitry involved in emotional-arousal, pain facilitation and autonomic responses may underlie the observed differences in symptoms, and in perceptual and emotional responses to aversive visceral stimuli.

Irritable bowel syndrome is more common in women regardless of the menstrual phase: a Rome II-based survey

Functional gastrointestinal disorders are more common in women in relation to the fluctuations of female sex hormones. We tried to know the gender-related differences in the prevalence of irritable bowel syndrome and gastrointestinal symptoms according to the menstrual phase. A total of 253 women before menopause and 252 men below age 50 were examined by a gastroenterologist after completing the questionnaire. Blood tests, endoscopic procedures, and imaging studies were done, if needed. Women were subclassified into three groups according to their menstruation period; menstrual phase, proliferative phase, and secretory phase. Finally, 179 men and 193 women were analyzed. Irritable bowel syndrome was more frequently noticed in women than in men (p=0.01). The diarrhea-dominant type was more common in men, while constipation-dominant or alternating types were more common in women (p<0.001). Of 193 women, there was no significant difference in their gastrointestinal symptoms according to their menstrual phase. Regardless of the menstrual phase, gastrointestinal symptoms are more frequent in women. Physicians should consider different symptomatic manifestations between men and women should be considered when evaluating functional gastrointestinal disorders.

Irritable bowel syndrome: current approach to symptoms, evaluation, and treatment

There are frequent advances in knowledge about the clinical presentation, pathophysiology, and treatment of irritable bowel syndrome. It is important for clinicians to be aware of available therapies and the supporting evidence for those therapies to increase patient satisfaction. This is best achieved with a collaborative and long-term clinician-patient relationship and mutual commitment to modify therapy and try new modalities until the greatest relief of symptoms and improvement in health-related quality of life is achieved. This article reviews symptoms, comorbidities, gender differences, and measure of severity in irritable bowel syndrome and current and evidence-based approaches to evaluation and treatment, and the new symptom-based Rome III diagnostic criteria are reviewed and explained.

Sex-dependent differences in the activity and modulation of N-methyl-d-aspartic acid receptors in rat dorsal root ganglia neurons

Women have greater temporal summation of experimental pain stimuli and also have a higher propensity for developing chronic visceral pain conditions. Sex hormone-mediated regulation of N-methyl-d-aspartic acid receptors (NMDARs) in nociceptive pathways is a plausible mechanism that may underlie these phenomena. The aim of this study was to compare the effect of 17-beta-estradiol (E2) in modulation of NMDAR activity in adult male and female rat dorsal root ganglia (DRG) neurons. DRG neurons were collected from adult male or female rats and grown in short-term culture in steroid-free media. NMDAR currents were recorded on small to medium size neurons by whole cell patch clamp using rapid perfusion with saturating concentrations of N-methyl-d-aspartic acid and glycine in the absence of extracellular Mg(2+). We found that the average density of NMDAR currents was 2.8-fold larger in DRG neurons from female rats compared with male rats (P<0.0001). Addition of 100 nM E2 increased NMDAR currents 55+/-15% in female neurons, but only 19+/-7% in male neurons. Potentiation was maximal after 20-40 min and dose dependent with an apparent 50% excitatory concentration of 17-23 nM. This effect was mimicked by E2 conjugated to BSA and attenuated by pretreatment with the protein tyrosine kinase inhibitor lavendustin A (1 microM) or the estrogen receptor (ER) antagonist, ICI 182,780 (1 microM), strongly suggesting activation of a cell surface ER acting through a non-genomic mechanism involving protein tyrosine kinases to increase NMDAR currents. These results identify sex-based differences in both the basal expression and the regulation of the NMDARs in DRG neurons.

Water avoidance stress activates colonic myenteric neurons in female rats

Stress stimulates colonic motor function and plays a role in functional bowel disorders, prevalently in women. We examined, in conscious female rats, the influence of water avoidance stress for 60 min on colonic myenteric neuron activity using immunohistochemical detection of Fos as a marker of neuronal activity. In control rats, Fos immunoreactive nuclei were rare in proximal and distal colon and no defecation was observed. Water avoidance stimulated fecal pellet output, which was associated with Fos expression in myenteric ganglia of proximal and distal colon including in a population of peripheral choline acetyltransferase-immunoreactive neurons. Atropine blocked fecal pellet output but not Fos expression in myenteric ganglia. These results indicate that psychological stress stimulates the activity of colonic cholinergic myenteric neurons.