Serotoninergic neuroenteric modulators

Therapeutic Potential of 1-(2-Chlorophenyl)-6,7-dimethoxy-3-methyl-3,4-dihydroisoquinoline

The synthesized compound 1-(2-chlorophenyl) 6-7-dimethoxy-3-methyl-3,4-dihydroisoquinoline (DIQ) was investigated as a biological agent. Its potential to affect muscle contractility was predicted through in silico PASS analysis. Based on the in silico analysis, its capabilities were experimentally investigated. The study aimed to investigate the effects of DIQ on the ex vivo spontaneous contractile activity (CA) of smooth muscle (SM) tissue. DIQ was observed to reduce the strength of Ca2+-dependent contractions in SM preparations (SMP), possibly by increasing cytosolic Ca2+ levels through the activation of a voltage-gated L-type Ca2+ channel. DIQ potently affected calcium currents by modulating the function of muscarinic acetylcholine receptors (mAChRs) and 5-hydroxytryptamine (5-HT) receptors at a concentration of 50 μM. Immunohistochemical tests showed a 47% reduction in 5-HT2A and 5-HT2B receptor activity in SM cells and neurons in the myenteric plexus (MP), further confirming the effects of DIQ. Furthermore, a significant inhibition of neuronal activity was observed when the compound was co-administered with 5-HT to SM tissues. The conducted experiments confirm the ability of the isoquinoline analog to act as a physiologically active molecule to control muscle contractility and related physiological processes.

2-Amino-N-Phenethylbenzamides for Irritable Bowel Syndrome Treatment

Irritable bowel syndrome (IBS) is a common gastrointestinal (GI) disorder characterized by abdominal pain or discomfort. Mebeverine is an antispasmodic that has been widely used in clinical practice to relieve the symptoms of IBS. However, its systemic use usually leads to side effects. Therefore, the current paper aimed to synthesize more effective medicines for IBS treatment. We used ring opening of isatoic anhydride for the synthesis in reaction with 2-phenylethylamine. In silico simulation predicted spasmolytic activity for 2-amino-N-phenethylbenzamides. The newly synthesized compounds demonstrated a relaxation effect similar to mebeverine but did not affect the serotonin or Ca2+-dependent signaling pathway of contractile activity (CA) in contrast. Having in mind the anti-inflammatory potential of antispasmodics, the synthesized molecules were tested in vitro and ex vivo for their anti-inflammatory effects. Four of the newly synthesized compounds demonstrated very good activity by preventing albumin denaturation compared to anti-inflammatory drugs/agents well-established in medicinal practice. The newly synthesized compounds also inhibited the expression of interleukin-1β and stimulated the expression of neuronal nitric oxide synthase (nNOS), and, consequently, nitric oxide (NO) synthesis by neurons of the myenteric plexus. This characterizes the newly synthesized compounds as biologically active relaxants, offering a cleaner and more precise application in pharmacological practice, thereby enhancing their potential therapeutic value.

Children and Adolescents with Irritable Bowel Syndrome: Treatment and Management

BACKGROUND

Irritable bowel syndrome (IBS) is a disorder that causes stomach pain in children and adolescents. It may also impact one's quality of life. IBS is linked to gastrointestinal issues such as diarrhoea and constipation. Despite the identification of several potential pathophysiological pathways, the aetiology of IBS remained unknown.

OBJECTIVE

The aim of this paper is to discuss the diagnosis, pathogenesis, case studies and treatment of Irritable bowel syndrome in children and adolescents.

METHODS

This systematic review covered relevant papers from the previous ten years that were accessible in Science Direct, Elsevier, NCBI, and Web of Science related to the pathophysiology and function of pharmacological drugs such as antidepressants, antispasmodics, prokinetics, and antibiotics in children with irritable bowel syndrome.

RESULTS

Only a few prospective therapy techniques have been investigated in children, and even fewer of those have been demonstrated to be effective. This article presents case studies including 50-59 children, which demonstrate a favourable acceptable impact that is more effective than a placebo in terms of reducing symptoms and improving the overall quality of life in children who have irritable bowel syndrome. Furthermore, the majority of the pathophysiological explanations and treatment options discussed are based on adult studies. These major issues arose when treating paediatric IBS, and they must be addressed in order to properly treat children with IBS. Trials that focus on many combinations of pharmacological and non-pharmacological therapies seem to be more helpful.

DISCUSSION

In recent years, a number of systematic reviews have been conducted to evaluate the efficacy of medication treatments in children for IBS; however, the dependability of these systematic reviews needs to be further investigated owing to the various experimental designs and levels of evidence used. This article highlights paediatric therapy options, including pharmaceutical medications such as antidepressants, antispasmodics, prokinetics, and antibiotics. The goal is to alleviate IBS symptoms while also enhancing the quality of life for children with this illness.

Re-evaluation of the Cardiovascular Safety Profile of Tegaserod: A Review of the Clinical Data

BACKGROUND AND AIMS

Tegaserod is a 5-HT₄ receptor agonist approved for irritable bowel syndrome with constipation in women <65 years of age without a history of cardiovascular ischemic events. Safety data are presented from 2 external adjudications from the 2018 Gastrointestinal Drugs Advisory Committee meeting supporting tegaserod's reintroduction after its voluntary 2007 withdrawal. Withdrawal was based on an internal adjudication using pooled placebo-controlled tegaserod data to identify potential cardiovascular ischemic signals.

METHODS

An independent committee conducted an external adjudication to evaluate 24 possible cardiovascular ischemic events (tegaserod: n = 20; placebo: n = 4) identified internally. A second independent external adjudication further evaluated these events.

RESULTS

A total of 18,645 patients were included (tegaserod: n = 11,614; placebo: n = 7031). The first adjudication identified 14 (0.075%) events (tegaserod: n = 13 [0.11%]; placebo: n = 1 [0.014%]). All patients had ≥1 cardiovascular risk factor, and 11 had ≥2. The second adjudication identified 390 events, 24 (0.13%) were classified as probable new or worsening events (tegaserod: 18 [0.16%]; placebo: 6 [0.09%]). For tegaserod, 7 (0.06%) were coronary or cerebrovascular ischemic events compared with 1 (0.01%) for placebo (odds ratio, 4.24; 95% confidence interval, 0.52-34.74; P = .273). All tegaserod patients reporting cardiovascular events had ≥1 risk, including cardiovascular disease, hyperlipidemia, ≥55 years of age, hypertension, diabetes, obesity, and smoking. Women <65 years of age without a history of cardiovascular ischemic events and ≤1 cardiovascular risk factor receiving tegaserod experienced no major adverse cardiovascular event(s).

CONCLUSIONS

Two independent, external adjudications suggest that tegaserod is safe for women <65 years of age with irritable bowel syndrome with constipation, no history of cardiovascular ischemic events, and ≤1 cardiovascular risk factor.

The Ketogenic Diet Improves Gut-Brain Axis in a Rat Model of Irritable Bowel Syndrome: Impact on 5-HT and BDNF Systems

Altered gut-brain communication can contribute to intestinal dysfunctions in the intestinal bowel syndrome. The neuroprotective high-fat, adequate-protein, low-carbohydrate ketogenic diet (KD) modulates the levels of different neurotransmitters and neurotrophins. The aim was to evaluate the effects of KD on levels of 5-HT, the receptors 5-HT_3B and 5-HT₄, the 5-HT transporter SERT, the neurotrophin BDNF, and its receptor TrkB in the colon and brain of a rat model of irritable bowel syndrome (IBS). Samples from Wistar rats exposed to maternal deprivation as newborns and then fed with a standard diet (IBS-Std) or KD (IBS-KD) for ten weeks were analyzed. As controls, unexposed rats (Ctrl-Std and Ctrl-KD) were studied. IBS-Std rats had a disordered enteric serotoninergic signaling shown by increased mucosal 5-HT content and reduced SERT, 5-HT_3B, and 5-HT₄ levels compared to controls. In the brain, these animals showed up-regulation of the BDNF receptor TrkB as a counteracting response to the stress-induced reduction of the neurotrophin. KD showed a dual effect in improving the altered 5-HT and BDNF systems. It down-regulated the increased mucosal 5-HT without affecting transporter and receptor levels. KD improved brain BDNF levels and established negative feedback, leading to a compensatory downregulation of TrkB to maintain a physiological steady state.

Role of Amine Neurotransmitters and Their Receptors in Skin Pigmentation: Therapeutic Implication

Skin pigmentation can occur due to increased melanin, including melanocyte proliferation, melanin biosynthesis, or melanocyte migration. There are many factors that influence the melanin production process, but the role of neurotransmitters in this process is still unclear. We found that histamine and serotonin influence the different stages of melanogenesis and melanogenesis, which increase melanogenesis. Since then, several related papers have been published, and from these papers, it has been recognised that the role of neurotransmitters in skin-pigment-related diseases needs to be summarised. By introducing the role of neurotransmitters in the regulation of various pigment disorders, including vitiligo and melasma, through this review, many researchers can be expected to try to apply neurotransmitter-related agonists and antagonists as treatments for skin pigment disorders.

Impact of serotonin transporter gene polymorphism on gut motility in patients with type 2 Diabetes mellitus

Background/Aims

The pathogenesis of gastrointestinal (GI) symptoms in patients with type 2 diabetes mellitus (T2DM) is yet to be delineated clearly. Serotonin, a monoamine neurotransmitter, resides primarily in the gut and plays a vital role in GI system. However, no study has been documented the role of serotonin and serotonin transporter gene (SLC6A4) polymorphism in the development of GI symptoms in T2DM patients.

Methods

Three hundred diabetes patients attending diabetes clinic at Postgraduate Institute of Medical Education and Research, Chandigarh, and matched healthy controls were enrolled for this study. Plasma from collected blood sample was used for serotonin measurement by enzyme-linked immunosorbent assay method and buffy coat was used for isolation of DNA by phenol chloroform method. Serotonin transporter gene polymorphism was analyzed by polymerase chain reaction method.

Results

The frequency of short allele (S) and SS genotype was significantly higher in patients with T2DM than controls and was associated with increased risk of T2DM. The frequency of LS genotype showed an association with protection from the disease. Regarding GI symptoms, 78.2% of patients with constipation showed LL and LS genotypes, and 97.7% of patients with diarrhea had SS genotype. The patients without GI symptoms did not show any association of gut motility with genotype. Furthermore, serotonin was significantly higher in diabetic patients who belonged to SS genotype compared to LS or LL genotype and who presented with diarrhea.

Conclusion

SS genotypes are prone to develop diarrhea because of faster gut motility resulting from higher serotonin levels as compared to LS and LL genotype in T2DM patients.

Irritable Bowel Syndrome and the Menstrual Cycle

Introduction: Irritable bowel syndrome (IBS) is a common gastrointestinal (GI) disorder. Female patients with bowel disease commonly report worsening of symptoms in the menstrual cycle. However, there is a paucity of data regarding IBS presentations' variation during different phases of the menstrual cycle. The current study aimed to evaluate the same in female IBS patients.

Materials and Methods: Consecutive premenopausal female patients with the diagnosis of IBS attending the outdoor (OPD) of Department of Gastroenterology and Gynaecology; IMS and SUM Hospital, Bhubaneswar, Odisha from June 2019 to December 2019 were included in the study and evaluated by a set of questionnaires regarding various presentations during all the three phases of the menstrual cycle.

Results: Consecutive 102 cases with the diagnosis of IBS were included in the study and evaluated. The mean age of presentation was in mid-30s. Most of the subjects suffered from IBS mixed (IBS-M) type. More patients significantly suffered from constipation (27.27%) during the luteal phase of their menstrual cycles than the menstrual period of their cycles (p - 0.009). More than 50% of all the cases suffered from abdominal bloating during all phases of the menstrual cycle, which was quite disturbing and affected the quality of life. These IBS patients were more symptomatic with more significant limitation of daily activities, suffered from low quality of life, and obtained physician consultation during the menstrual phase as compared to other cycle stages.

Conclusion: Premenopausal female patients with IBS become much more symptomatic during the menstrual phase of the cycle than other stages of the cycle.

Scientific Evidence for the Treatment of Children with Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is one of the most common functional gastro-intestinal disorders which significantly impacts the quality of life of affected children. Abdominal pain improved by defecation, associated with a change in stool form and frequency, represents its specific clinical marker. Even if a number of potential patho-physiological mechanisms have been described, the exact underlying etiology of IBS is so far unclear. Likewise, no optimal treatment has ever been found neither for adult nor for pediatric patients. Current therapeutic options include drugs, dietary interventions and biopsychosocial therapies. The present review aims at evaluating the scientific evidence supporting the efficacy of these treatments for children with IBS.

YH12852, a Potent and Selective Receptor Agonist of 5-hydroxytryptamine, Increased Gastrointestinal Motility in Healthy Volunteers and Patients With Functional Constipation

Gastrointestinal (GI) motility disorders are common, decreases quality of life, and imposes a substantial economic burden. YH12852 is a novel agonist of 5‐hydroxytryptamine for the treatment of GI motility disorders. This phase I/IIa study assessed the tolerability, pharmacodynamic (PD) and pharmacokinetic (PK) profiles of YH12852. In the multiple dose (MD) cohort, healthy subjects and patients with functional constipation were randomized and received orally YH12852 at 0.3, 0.5, 1, 2, or 3 mg or prucalopride 2 mg or their matching placebo, once daily for 14 days after breakfast. In the multiple low‐dose cohort (MLD), healthy subjects randomly received once‐daily oral doses of YH12852 at 0.05 or 0.1 mg for 14 days after breakfast. Questionnaires, gastric emptying breath test for PDs, and plasma samples for PKs were collected. In the MD cohort, a total of 56 subjects (29 healthy volunteers and 27 patients with functional constipation) were randomized, of whom 48 completed the study. In the MLD cohort, a total of 16 healthy subjects were randomized, and 15 subjects completed the study. YH12852 increased the average weekly frequency of spontaneous bowel movements and loosened the stool. In addition, YH12852 increased quality of life satisfaction, and decreased severity of constipation symptom and GI symptoms. YH12852 was safe and well‐tolerated up to 3 mg and showed nearly dose proportional PKs. In conclusion, YH12852 was safe and enhanced GI motility. YH12852 can be developed as an effective treatment option for GI motility disorders, including functional constipation. Further studies are warranted to confirm this possibility.

The Association Between Constipation or Stool Consistency and Pain Severity in Patients With Chronic Pain

Background

Bacteria can influence a variety of gut functions. Some studies showed that stool consistency and constipation were associated with gut microbiome (GM) composition, and enterotype, dysbiosis. Growing evidence indicates the significant role of GM in the homeostatic function of the host body. The GM may regulate multiple neurochemical and neurometabolic pathways. Chronicity of the pain is actively modulated at the molecular to the network level by means of several neurotransmitters. The GM to some extent can affect pain perception.

Objectives

The current study aimed at investigating the relationship between constipation state or usual stool form and pain severity of patients with chronic pain.

Methods

The current study was conducted on 365 patients with chronic pain. The participants were evaluated on their stool form (the Bristol stool form scale; BSFS), constipation state (the Cleveland clinic constipation score; CCCS), body mass index (BMI), and usual pain severity (numerical rating scale; NRS). In addition, the participants were assigned into five groups according to the pain region (i e, low back and/or lower limb, whole body, neck and/or upper back and/or upper limb, head and/or face, chest and/or abdominal).

Results

The CCS showed a significant and positive association with the pain severity of the total patients and patients with low back and/or lower limb pain. Simultaneous multiple linear regression analyses revealed that a predictor of the pain severity was the CCS for the total patients and patients with low back and/or lower limb, whole body pain.

Conclusions

Constipation displayed a significant and positive association with the pain severity of the total patients and patients with low back and/or lower limb pain, whole body.

Dysregulation of GABAergic Signalling Contributes in the Pathogenesis of Diarrhea-predominant Irritable Bowel Syndrome

Background/Aims

Diarrhea-predominant irritable bowel syndrome (IBS-D) is a prevalent functional bowel disorder. Abdominal pain, discomfort and altered intestinal habits are the salient features of IBS-D. Low grade inflammation and altered neurotransmitters are the 2 recently identified factors contributing to the pathogenesis of IBS-D, but their role and interactions has not been elucidated in detail. Here we investigate the potential role of γ-aminobutyric acid (GABA) in regulating gut inflammation during IBS-D.

Methods

Blood samples and colonic mucosal biopsies from clinically diagnosed IBS-D patients and controls were collected. Levels of GABA were measured in serum samples through enzyme-linked immunosorbent assay (ELISA). Expression of GABAergic system and proinflammatory cytokines were analyzed in biopsy samples by reverse transcriptase polymerase chain reaction (RT-PCR). Effect of GABA and its antagonist on the expression of proinflammatory cytokines in lipopolysaccharide (LPS)-stimulated HT-29 cells was examined through RT-PCR.

Results

ELISA data revealed diminished level of GABA in IBS-D patients as compared to controls. RT-PCR analysis showed altered GABAergic signal system in IBS-D patients as compared to controls. GABA reduced the expression of proinflammatory cytokines in LPS stimulated HT-29 cells, whereas bicuculline methiodide (GABA antagonist) upregulated the expression of same cytokines in LPS stimulated HT-29 cells.

Conclusions

Our sets of data indicate that diminished level of GABA and altered GABAergic signal system contributes to pathogenesis of IBS-D by regulating inflammatory processes. These results provide novel evidence for anti-inflammatory role of GABA in IBS-D patients by altering the expression of pro-inflammatory cytokines.

Medically unexplained syndromes: irritable bowel syndrome, fibromyalgia and chronic fatigue

This is a review of three of the more common medically unexplained syndromes that present for treatment to liaison psychiatry services in general medical hospitals: chronic fatigue syndrome, fibromyalgia and irritable bowel syndrome. The three are interrelated, extremely disabling and comorbid mood disorders are frequent. In general, treatment, whether psychological or medical, has very modest impact. The disputed classification of medically unexplained syndromes is also reviewed. There is a clear gulf between the views and experiences of patients with these syndromes and the medical establishment. In this article I summarise give the evidence for pharmacological, psychosocial and ‘alternative’ or ‘complementary’ interventions for a range of disorders, about which there is some dispute. I leave it to the reader to decide which interventions hold the most promise.

LEARNING OBJECTIVES

•

DECLARATION OF INTEREST

None.

Plasma serotonin level is a predictor for recurrence and poor prognosis in colorectal cancer patients

AIM

To investigate the prognostic value of plasma serotonin levels in colorectal cancer (CRC).

PATIENTS AND METHODS

Preoperative plasma serotonin levels of 150 healthy control (HC) cases, 150 benign colorectal polyp (BCP) cases, and 176 CRC cases were determined using radioimmunoassay assay. Serotonin levels were compared between HC, BCP, and CRC cases, and those in CRC patients were related to 5-year outcome.

RESULTS

Plasma serotonin levels were markedly higher in CRC patients than in either HCs or BCP cases. An elevated serotonin level was significantly associated with advanced tumor node metastasis. Receiver operating characteristic curve analysis showed that the level of serotonin had a high predictive value for disease recurrence and mortality. Multivariate analysis revealed that high serotonin level was significantly associated with poor recurrence-free survival and overall survival.

CONCLUSION

Our results suggest that a high peri-operative plasma serotonin level is useful as a prognostic biomarker for CRC recurrence and poor survival.

Prokinetic effects of LD02GIFRO on functional gastrointestinal disorder in rats

LD02GIFRO is a novel prokinetic agent formulated with Poncirus fructus and Zanthoxylum sp. fruits. The aim of the present study was to evaluate the effect of LD02GIFRO on delayed gastrointestinal transit (GIT) and colorectal hypersensitivity. To investigate the effect of LD02GIFRO, a rat model of delayed GIT was induced via three mechanisms; postoperative ileus (POI), morphine, and POI plus morphine. Visceromotor responses (VMR) to colorectal distension (CRD) were also evaluated. POI was induced by laparotomy surgery and manipulation of the small intestine under anesthesia, and GIT was calculated by measuring the length that Evans Blue travelled through the gastrointestinal tract in a given time. Oral administration of 260 mg/kg LD02GIFRO caused Evans Blue to migrate significantly further in the delayed GIT models induced by POI, morphine and POI plus morphine compared with the control (P<0.05). This effect was inhibited by atropine, a muscarinic receptor antagonist, and completely abolished by GR125487, a 5-HT₄-receptor antagonist. Furthermore, intraperitoneal administration of 600 and 900 mg/kg LD02GIFRO significantly reduced VMR to CRD in acute and chronic colorectal hypersensitive rat models, induced by acetic acid and trinitrobenzenesulfonic acid, to almost normal levels (P<0.01). In the present study, LD02GIFRO successfully ameliorated delayed GIT models and colorectal hypersensitivity models, suggesting that LD02GIFRO may be an effective therapeutic treatment for patients with functional gastrointestinal disorders and abnormalities in GIT.

5-HT3 receptors promote colonic inflammation via activation of substance P/neurokinin-1 receptors in dextran sulphate sodium-induced murine colitis

BACKGROUND AND PURPOSE

5-HT (serotonin) regulates various physiological functions, both directly and via enteric neurons. The present study investigated the role of endogenous 5-HT and 5-HT3 receptors in the pathogenic mechanisms involved in colonic inflammation, especially in relation to substance P (SP) and the neurokinin-1 (NK1 ) receptor.

EXPERIMENTAL APPROACH

The effects of 5-HT3 and NK1 receptor antagonists were examined in dextran sulphate sodium (DSS)-induced colitis in mice. Inflammatory mediator expression and the distribution of 5-HT3 and NK1 receptors were also determined.

KEY RESULTS

Daily administration of ramosetron and ondansetron (5-HT3 antagonists) dose-dependently attenuated the severity of DSS-induced colitis and up-regulation of inflammatory mediator expression. Immunohistochemical analysis showed 5-HT3 receptors are mainly expressed in vesicular ACh transporter-positive cholinergic nerve fibres in normal colon. DSS increased the number of colonic nerve fibres that were double positive for 5-HT3 receptors and SP but not of those that were double positive for 5-HT3 receptors and vesicular ACh transporter. DSS increased colonic SP levels and SP-positive nerve fibres; these responses were attenuated by ramosetron. DSS-induced colitis and up-regulation of inflammatory mediators were attenuated by aprepitant, an NK1 antagonist. Immunohistochemical studies further revealed that DSS treatment markedly increased NK1 receptor expression in CD11b-positive cells.

CONCLUSIONS AND IMPLICATIONS

These findings indicate that the 5-HT/5-HT3 receptor and SP/NK1 receptor pathways play pathogenic roles in colonic inflammation. 5-HT acts via 5-HT3 receptors to up-regulate inflammatory mediators and promote colonic inflammation. These effects may be further mediated by activation of macrophage NK1 receptors via SP released from 5-HT3 receptor-positive nerve fibres.

Mechanism-based management for mucositis: option for treating side effects without compromising the efficacy of cancer therapy

Mucositis is a major side effect induced by chemotherapy and radiotherapy. Although mucositis is a leading cause of morbidity and mortality in cancer patients, management is largely limited to controlling symptoms, and few therapeutic agents are available for treatment. Since mucositis could be inhibited by the modulation of radiotherapy- or chemotherapy-induced pathways independently of cancer treatment, there is an opportunity for the development of more targeted therapies and interventions. This article examined potential therapeutic agents that have been investigated for the prevention and/or inhibition of mucositis induced by conventional chemotherapy and radiotherapy. They can be classified according to their mechanisms of action: scavenging reactive oxygen species, inhibition of specific cytokine production or inflammation, and inhibition of apoptosis. These early events may be good target pathways for preventing the pathogenesis of mucositis. Considering that both cancer therapy and therapeutic agents for mucositis act on both normal and cancer cells, agents that inhibit mucositis should act through mechanisms that selectively protect normal cells without compromising cancer treatment. Therefore, mechanism-based guidance for the treatment of mucositis is critical to prevent risky treatments for cancer patients and to relieve detrimental side effects effectively from cancer therapy.

Gut-Microbiota-Brain Axis and Its Effect on Neuropsychiatric Disorders With Suspected Immune Dysregulation

PURPOSE

Gut microbiota regulate intestinal function and health. However, mounting evidence indicates that they can also influence the immune and nervous systems and vice versa. This article reviews the bidirectional relationship between the gut microbiota and the brain, termed the microbiota-gut-brain (MGB) axis, and discusses how it contributes to the pathogenesis of certain disorders that may involve brain inflammation.

METHODS

Articles were identified with a search of Medline (starting in 1980) by using the key words anxiety, attention-deficit hypersensitivity disorder (ADHD), autism, cytokines, depression, gut, hypothalamic-pituitary-adrenal (HPA) axis, inflammation, immune system, microbiota, nervous system, neurologic, neurotransmitters, neuroimmune conditions, psychiatric, and stress.

FINDINGS

Various afferent or efferent pathways are involved in the MGB axis. Antibiotics, environmental and infectious agents, intestinal neurotransmitters/neuromodulators, sensory vagal fibers, cytokines, and essential metabolites all convey information to the central nervous system about the intestinal state. Conversely, the hypothalamic-pituitary-adrenal axis, the central nervous system regulatory areas of satiety, and neuropeptides released from sensory nerve fibers affect the gut microbiota composition directly or through nutrient availability. Such interactions seem to influence the pathogenesis of a number of disorders in which inflammation is implicated, such as mood disorder, autism-spectrum disorders, attention-deficit hypersensitivity disorder, multiple sclerosis, and obesity.

IMPLICATIONS

Recognition of the relationship between the MGB axis and the neuroimmune systems provides a novel approach for better understanding and management of these disorders. Appropriate preventive measures early in life or corrective measures such as use of psychobiotics, fecal microbiota transplantation, and flavonoids are discussed.

Role of serotonin signaling system in gastrointestinal tract: Implications for regulatory effect of acupuncture and moxibustion on irritable bowel syndrome

The 5-hydroxytryptamine (serotonin, or 5-HT) signaling system plays a key role in the gastrointestinal tract. There have been many studies on the 5-HT signaling system involved in the gastrointestinal tract. This article reviews the recent advances in the knowledge of 5-HT signaling pathways in the gastrointestinal tract, including 5-HT receptor types and subtypes, their distribution in the gastrointestinal tract, physiological and pathological roles of the 5-HT signal system in the gastrointestinal tract, and the change of the 5-HT signal pathway in the gastrointestinal tract. On the basis of the understanding of the above knowledge, we discuss how acupuncture and moxibustion regulate gastrointestinal diseases, especially IBS, through the 5-HT signal system.

Symptomatology of irritable bowel syndrome and inflammatory bowel disease during the menstrual cycle

Gender-related physiological variations in gastrointestinal (GI) symptomatology have been observed in women of reproductive age. Many women experience cyclical changes in GI symptomatology during their menstrual cycle, particularly alteration in their bowel habits. Physiological studies of healthy women during the menstrual cycle showed a prolonged GI transit time during the luteal phase, either in the oro-cecum route or in the colon. Worsened GI symptoms, such as abdominal pain, bloating or diarrhea are observed in patients with irritable bowel syndrome (IBS) during menses. This may be due to elevated prostaglandin levels during menses, with an enhanced perception of viscera-somatic stimuli resulting in nausea, abdominal distension and pain. Also patients with IBS or IBD demonstrate a cyclical pattern more closely related to their bowel habits than healthy controls. Women with inflammatory bowel disease (IBD) also have exacerbated symptoms during menses; however, it is unclear whether this relates to physiological variation or disease exacerbation in IBS or IBD. Studies examining the association of the menstrual cycle and GI symptomatology in patients with IBS or IBD, have not yet clarified the underlying mechanisms. Moreover medications—such as non-steroidal anti-inflammatory drugs and oral contraceptive pills used for dysmenorrhea and menstrual migraine in those patients have not well been controlled for in the previous studies, which can contribute to further bias. Understanding changes in GI symptomatology during the menstrual cycle may help to determine the true extent of disease exacerbation and proper management strategy.

Brain and gut interactions in irritable bowel syndrome: new paradigms and new understandings

Irritable bowel syndrome (IBS) is characterized by abdominal pain and altered bowel habits. Visceral hypersensitivity is believed to be a key underlying mechanism that causes pain. There is evidence that interactions within the brain and gut axis (BGA), that involves both the afferent-ascending and the efferent-descending pathways, as well as the somatosensory cortex, insula, amygdala, anterior cingulate cortex, and hippocampus, are deranged in IBS showing both the activation and inactivation. Clinical manifestations of IBS such as pain, altered gut motility, and psychological dysfunction may each be explained, in part, through the changes in the BGA, but there is conflicting information, and its precise role is not fully understood. A better understanding of the BGA may shed more knowledge regarding the pathophysiology of IBS that in turn may lead to the discovery of novel therapies for this common disorder.

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

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

New treatment targets for the management of irritable bowel syndrome

PURPOSE OF REVIEW

Irritable bowel syndrome (IBS) and chronic idiopathic constipation (CIC) are highly prevalent medical conditions that reduce quality of life and represent a substantial economic burden on healthcare cost. Until recently, no specific treatment options were available. This review will provide an update of the most recent randomized clinical trials data showing efficacy and safety of novel, targeted treatment modalities in IBS and CIC with gastrointestinal receptor and ion channel agonists.

RECENT FINDINGS

Recent discoveries of peptides and small molecules targeting gastrointestinal receptors and ion channels resulted in novel, specific pharmacological therapies of IBS and CIC. The bicyclical fatty acid lubiprostone and the synthetic 14-amino acid peptide linaclotide were identified to selectively activate a Chloride Channel-2 and the Guanylin Cyclase-C receptor, respectively, and demonstrate efficacy in the treatment of IBS with constipation and CIC.

SUMMARY

Novel molecules including the bicyclical fatty acid lubiprostone and the synthetic 14-amino acid peptide linaclotide represent new treatment modalities for IBS with constipation and CIC with proven efficacy and acceptable side-effect profiles.

Effects of 5-HT2B, 5-HT3 and 5-HT4 receptor antagonists on gastrointestinal motor activity in dogs

AIM: To study the effects of 5-hydroxytryptamine (5-HT) receptor antagonists on normal colonic motor activity in conscious dogs.

METHODS: Colonic motor activity was recorded using a strain gauge force transducer in 5 dogs before and after 5-HT2B, 5-HT3 and 5-HT4 receptor antagonist administration. The force transducers were implanted on the serosal surfaces of the gastric antrum, terminal ileum, ileocecal sphincter and colon. Test materials or vehicle alone was administered as an intravenous bolus injection during a quiescent period of the whole colon in the interdigestive state. The effects of these receptor antagonists on normal gastrointestinal motor activity were analyzed.

RESULTS: 5-HT2B, 5-HT3 and 5-HT4 receptor antagonists had no contractile effect on the fasting canine terminal ileum. The 5-HT3 and 5-HT4 receptor antagonists inhibited phase III of the interdigestive motor complex of the antrum and significantly inhibited colonic motor activity. In the proximal colon, the inhibitory effect was dose dependent. Dose dependency, however, was not observed in the distal colon. The 5-HT2B receptor antagonist had no contractile effect on normal colonic motor activity.

CONCLUSION: The 5-HT3 and 5-HT4 receptor antagonists inhibited normal colonic motor activity. The 5-HT2B receptor antagonist had no contractile effect on normal colonic motor activity.

The prevalence and clinical characteristics of primary headache in irritable bowel syndrome: a subgroup of the functional somatic syndromes

CONTEXT

The irritable bowel syndrome and primary headache are two chronic diseases characterized by symptoms of recurring pain and affect approximately 10%-20% of the general population.

OBJECTIVES

To study the prevalence of primary headache in volunteers with irritable bowel syndrome in a Brazilian urban community.

METHODS

It was evaluated the prevalence of primary headache associated with irritable bowel syndrome in adult volunteers 330 no patients.The protocol included the Rome III criteria, international classification of Headaches, later divided into four groups: I- Irritable bowel syndrome (n = 52), II- Primary headache (n = 45), III-Irritable bowel syndrome (n = 26) and headache, and IV- Controls (207).

RESULTS

We not found significant difference in the average age of the four groups and the diagnosis of irritable bowel syndrome, primary headache and their association was more frequent in females. The frequent use of analgesics was greater in groups II and III.

CONCLUSION

Our results suggest that irritable bowel syndrome and primary headache are also common in third world countries. The frequency in use of analgesics in association between the two entities was relevant. The identification of irritable bowel syndrome patients with different clinical sub-types could improve the therapeutics options and the prevention strategies.

5-HT₃ receptor antagonists ameliorate 5-fluorouracil-induced intestinal mucositis by suppression of apoptosis in murine intestinal crypt cells

BACKGROUND AND PURPOSE

Chemotherapeutic agents, including 5-fluorouracil (5-FU), frequently cause intestinal mucositis resulting in severe diarrhoea and morphological mucosal damage. 5-HT₃ receptor antagonists are clinically effective in the treatment of nausea and emesis during cancer chemotherapy. Therefore we here have examined the effects of 5-HT₃ receptor antagonists on 5-FU-induced intestinal mucositis in mice.

EXPERIMENTAL APPROACH

Intestinal mucositis was induced in male C57BL/6 mice by daily administration of 5-FU (50 mg·kg⁻¹) for 5 days. Effects of 5-HT₃ receptor antagonists, ramosetron (0.01-0.1 mg·kg⁻¹) and ondansetron (5 mg·kg⁻¹), on the accompanying histology, cytokine production and apoptosis were assessed.

KEY RESULTS

Continuous administration of 5-FU to mice caused severe intestinal mucositis, which was histologically characterized by the shortening of villi and destruction of intestinal crypts, accompanied by body weight loss and diarrhoea. Daily ramosetron administration dose-dependently reduced the severity of intestinal mucositis, body weight loss and diarrhoea. Similar beneficial effects were observed with ondansetron. The number of apoptotic, caspase-3- and caspase-8-activated cells increased 24 h after the first 5-FU administration, and these responses were reduced by ramosetron. The up-regulation of TNF-α, IL-1β and IL-6 following 5-FU treatment was also attenuated by ramosetron.

CONCLUSIONS AND IMPLICATIONS

5-HT₃ receptor antagonists ameliorated 5-FU-induced intestinal mucositis in mice, and this action could result from suppression of apoptotic responses in the intestinal crypt cells via inhibition of cytokine expression. Thus, 5-HT₃ receptor antagonists may be useful for preventing not only nausea and emesis but also intestinal mucositis during 5-FU chemotherapy.

Identification of multiple 5-HT₄ partial agonist clinical candidates for the treatment of Alzheimer's disease

The cognitive impairments observed in Alzheimer's disease (AD) are in part a consequence of reduced acetylcholine (ACh) levels resulting from a loss of cholinergic neurons. Preclinically, serotonin 4 receptor (5-HT(4)) agonists are reported to modulate cholinergic function and therefore may provide a new mechanistic approach for treating cognitive deficits associated with AD. Herein we communicate the design and synthesis of potent, selective, and brain penetrant 5-HT(4) agonists. The overall goal of the medicinal chemistry strategy was identification of structurally diverse clinical candidates with varying intrinsic activities. The exposure-response relationships between binding affinity, intrinsic activity, receptor occupancy, drug exposure, and pharmacodynamic activity in relevant preclinical models of AD were utilized as key selection criteria for advancing compounds. On the basis of their excellent balance of pharmacokinetic attributes and safety, two lead 5-HT(4) partial agonist candidates 2d and 3 were chosen for clinical development.

Serotonin and ionizing radiation synergistically affect proliferation and adhesion molecule expression of malignant melanoma cells

BACKGROUND

Mast cells are key effectors of the immune system and are involved in a variety of physiological and pathophysiological processes. Dermal mast cells have been demonstrated to degranulate as a consequence of ionizing radiation exposure. Mast cells accumulate at the periphery of skin tumours including malignant melanoma. Melanoma cells thus represent a potential target for the action of mediators released from irradiated mast cells.

OBJECTIVE

In this study, we evaluated the effects of serotonin and ionizing radiation on the proliferation and the adhesion molecule expression of malignant melanoma cells.

METHODS

Human mast cells (HMC-1) were examined for serotonin release after irradiation using an enzyme-linked immunosorbent assay (ELISA). Protein expression of serotonin receptors and adhesion molecules on human melanoma cells (IPC-298) was investigated by flow cytometry. Cell attachment to fibronectin was determined by an adhesion assay. Proliferation and cell cycle kinetics were analysed by proliferation assay and 5-bromodeoxyuridine (BrdU)/DNA dual parameter flow cytometry, respectively.

RESULTS

Ionizing radiation exposure resulted in serotonin release by HMC-1 cells. Expression of serotonin receptors was detected on IPC-298 cells. Serotonin enhanced the radiation-induced reduction in melanoma cell proliferation. Serotonin and ionizing radiation synergistically increased the expression of adhesion molecules on melanoma cells and improved cell adhesion to fibronectin. The up-regulation of cellular adhesion molecule expression was attenuated by inhibitors to phosphatidylinositol 3-kinase, mitogen-activated protein (MAP) ERK kinase and protein kinase C.

CONCLUSIONS

Our data suggest that serotonin released from irradiated dermal mast cells modulates the radiation response of human melanoma cells. We postulate that radiation-induced mast cell degranulation and mediator release have a great impact on malignant melanoma cell development.

Dual role of serotonin in the pathogenesis of indomethacin-induced small intestinal ulceration: pro-ulcerogenic action via 5-HT3 receptors and anti-ulcerogenic action via 5-HT4 receptors

Serotonin (5-HT) exerts multiple physiological functions not only in the central and peripheral nervous systems but also in the gastrointestinal tract, and these multiple functions are accounted for by a variety of 5-HT receptor subtypes. We investigated the role of 5-HT in the pathogenesis of indomethacin-induced intestinal lesions in mice, in relation to 5-HT receptor subtypes. A single oral administration of indomethacin (10 mg/kg) provoked damage in the small intestine of mice 24 h later, and this response was prevented by pretreatment with p-chlorophenylalanine (a 5-HT synthesis inhibitor). The administration of 5-HT3 receptor antagonists, such as ondansetron and ramosetron, dose-dependently reduced the severity of the intestinal lesions, whereas a high dose of GR113808 (a 5-HT4 receptor antagonist) significantly aggravated these lesions. In contrast, NAN-190 (a 5-HT1 receptor antagonist), ketanserin (a 5-HT2 receptor antagonist), and SB269970 (a 5-HT7 receptor antagonist) had no effect on these lesions. Mosapride (a 5-HT4 receptor agonist) significantly reduced the severity of indomethacin-induced intestinal lesions, and this protective effect was totally prevented by either GR113808 or methyllycaconitine (an α7-nicotinic acetylcholine receptor antagonist). Indomethacin increased the activity of myeloperoxidase and the expression of inducible nitric oxide synthase, inflammatory cytokines, and chemokines in the small intestine; these responses were significantly attenuated by ondansetron and mosapride. These findings suggest that endogenous 5-HT exerts a dual role in the pathogenesis of indomethacin-induced intestinal lesions: pro-ulcerogenic action via 5-HT3 receptors and anti-ulcerogenic action via 5-HT4 receptors, and the latter effect via 5-HT4 receptors may be mediated by activation of α7-nicotinic acetylcholine receptors.

The effects of 5-HT4 receptor agonist, mosapride citrate, on visceral hypersensitivity in a rat model

BACKGROUND AND AIMS

Mosapride citrate is known to affect gastric motility. However, whether mosapride citrate has any effect on visceral pain in the colon or rectum is not certain. The aim of this study was to assess the effects of mosapride citrate on visceral pain in a rat visceral hypersensitivity model.

METHODS

The perception of visceral pain was evaluated by the visceromotor response to colorectal distension observed on electromyographs of the abdominal musculature in urethane-anesthetized rats. Visceral hypersensitivity was induced by the intrarectal instillation of 4% acetic acid or 1.5% zymosan. Mosapride citrate was administered intraperitoneally 3 h later. VMRs to CRD were recorded prior to the instillation of acetic acid or zymosan and before and after mosapride citrate treatment.

RESULTS

The intracolonic instillation of acetic acid resulted in a significant increase in VMRs of the abdominal muscles to CRD, compared with the pretreatment state (174 ± 24%, P < 0.05). The intracolonic instillation of zymosan resulted in a significant increase in VMRs of the abdominal muscles to CRD, compared with the pretreatment state (144 ± 9%, P < 0.05). Intraperitoneal injection of mosapride citrate resulted in a significant reduction in the VMRs to CRD in an acetic acid-induced visceral hypersensitivity rat model (61 ± 9%, P < 0.05). The intraperitoneal injection of mosapride citrate also resulted in a significant reduction in the VMRs to CRD in a zymosan-induced visceral hypersensitivity rat model (67 ± 9%, P < 0.05).

CONCLUSIONS

Mosapride citrate diminished visceral pain in rats.

Serotonin receptor modulators in the treatment of irritable bowel syndrome

The aim of this article is to review the pathophysiology and clinical role of serotonin receptor modulators used in the treatment of irritable bowel syndrome. Serotonin is an important monoamine neurotransmitter that plays a key role in the initiation of peristaltic and secretory refl exes, and in modulation of visceral sensations. Several serotonin receptor subtypes have been characterized, of which 5HT3, 5HT4, and 5HT1b are the most important for GI function. 5HT4 agonists (eg, tegaserod) potentiate peristalsis initiated by 5HT1 receptor stimulation. 5HT4 agonists are therefore useful in constipation predominant form of IBS and in chronic constipation. 5HT3 antagonists (Alosetron and Cilansetron) prevent the activation of 5HT3 receptors on extrinsic afferent neurons and can decrease the visceral pain associated with IBS. These agents also retard small intestinal and colonic transit, and are therefore useful in diarrhea-predominant IBS. Tegaserod has been demonstrated in several randomized, placebo controlled trials to relieve global IBS symptoms as well as individual symptoms of abdominal discomfort, number of bowel movements and stool consistency. Several randomized, controlled trials have shown that alosetron relieves pain, improves bowel function, and provides global symptom improvement in women with diarrhea-predominant irritable bowel syndrome. However, ischemic colitis and severe complications of constipation have been major concerns leading to voluntary withdrawal of Alosetron from the market followed by remarketing with a comprehensive risk management program.

Pharmacological mechanism responsible for the Atractylodes japonica-induced distal colonic contraction in rats

BACKGROUND AND AIM

Atractylodes japonica Koidz (Compositae) has been commonly used to treat the gastrointestinal (GI) disorders in Korean traditional medicine, but its pharmacological roles in the regulation of GI motility have not been clarified yet.

METHODS

Atractylodes japonica was sequentially partitioned with MeOH, n-hexane, CHCl(3), EtOAc and n-BuOH saturated with H(2)O, and the effects of Atractylodes japonica extracts on the spontaneous contractility of GI muscle strips prepared from rats were measured.

RESULTS

Among five different fractionations, EtOAc extracts of Atractylodes japonica (AJEA) dose-dependently increased the low frequency contraction of distal colon longitudinal muscles (DCLM), and the ED(50) values were revealed to be 1.71×10(-9) g/ml. Among GI tracts, a prominent contractile response to AJEA was observed only in the DCLM. The contractile patterns produced by AJEA remarkably differed from those caused by acetylcholine and 5-HT. 4-DAMP and methoctramine at 0.5 μM significantly blocked the AJEA (1.0 μg/ml)-induced contraction of DCLM, but ondansetron, GR113808 and methysergide at 1.0 μM in combination did not change the AJEA-induced DCLM contractions. Acetylethylcholine mustard (5.0 μM) significantly diminished the AJEA-induced DCLM contractions, whereas p-chlorophenyl alanine (1.0 μM) did not affect the stimulatory effects of AJEA on the DCLM contractions.

CONCLUSION

The present results suggest that AJEA may specifically act on the DCLM among GI smooth muscles, and AJEA-induced DCLM contraction is likely mediated, at least, by activation of ChAT and acetylcholinergic muscarinic receptors.

Acetylene compound isolated from Atractylodes japonica stimulates the contractility of rat distal colon via inhibiting the nitrergic-purinergic relaxation

AIM OF THE STUDY

Our previous research has showed that rhizome of Atractylodes japonica Koidz (Compositae) exhibits an increase in the spontaneous contractility of distal colon in rats. The aims of this study are to identify the phytochemical(s), which stimulate(s) the colonic contractility, contained in Atractylodes japonica and to evaluate the pharmacological mechanism responsible for the colonic muscle contraction.

MATERIALS AND METHODS

Based on the stimulatory activity-guided fractionation on the isometric contraction of rat distal colonic strips, atractylodiol (ATD) and diacetyl-atractylodiol (DATD) were isolated from the CHCl(3) fractions of Atractylodes japonica.

RESULTS

ATD and DATD dose-dependently increased both tension and amplitude of distal colon longitudinal muscle (DCLM), but they stimulated only amplitude in the distal colon circular muscle. The ED(50) values of ATD and DATD to stimulate the amplitude of DCLM were revealed as 9.1×10(-9)M and 1.8×10(-8)M, respectively. l-NAME (0.1mM) significantly increased the ADT (1μM)-induced contraction of DCLM, whereas SNAP (0.1mM) markedly reduced the stimulatory effects of ATD on DCLM contractility. The combined effects of SNAP and atropine (0.5μM) on the ATD-induced contraction of DCLM were similar to the inhibitory effects of SNAP alone. Suramin (0.1mM) significantly enhanced the increase of ATD-induced DCLM contraction, whereas ADPβS (0.1mM) markedly abolished the stimulatory effects of ATD on the spontaneous contractility of DCLM.

CONCLUSIONS

The present results demonstrate that acetylene compounds, ATD and DATD, are the effective phytochemical of Atractylodes japonica to stimulate the motility of distal colon in rats, and ATD possibly enhances the spontaneous contractility of distal colon through inhibiting the mechanism of nitrergic-purinergic relaxation.

Investigational agents for the irritable bowel syndrome

IMPORTANCE OF THE FIELD

Irritable bowel syndrome (IBS) is a common disorder with significant health and economic consequences. The etiology of IBS is complex and appears to be multifactorial. Traditional IBS therapies have been directed primarily at the relief of individual symptoms but have been largely disappointing. This has triggered the search for newer treatment strategies with improved patient outcomes.

AREAS COVERED IN THIS REVIEW

Enhanced knowledge about the putative pathophysiology of IBS has allowed the identification of new mechanistic targets for treatment. Our aim is to review emerging and promising drugs in the treatment of IBS based on disease pathophysiology. Data were extracted using Medline and PubMed search engines until January 2010. Abstracts were identified through 'Web of Science' and abstract supplements of major gastrointestinal scientific meetings. Drugs were classified according to mechanism of action and those with efficacy in trials involving human subjects examined.

WHAT THE READER WILL GAIN

Additional insight into the pathophysiology as well as current and prospective treatments of IBS.

TAKE HOME MESSAGE

A multitude of putative drug targets have been identified and some novel treatments have progressed through to human clinical trials, but very few will be approved for the market in the near future. Moreover, and in keeping with the complex and multifactorial nature of this syndrome, it is unlikely that there will be one dominant and universally effective form of therapy for all IBS patients.

Radiation-induced mast cell mediators differentially modulate chemokine release from dermal fibroblasts

BACKGROUND

Ionizing radiation has been demonstrated to result in degranulation of dermal mast cells. Chemokines are thought to play a crucial role in the early phase of the cutaneous radiation reaction. In human skin, mast cells are located in close proximity to dermal fibroblasts, which thus are a potential target for the action of mast cell mediators.

OBJECTIVE

In this study, we evaluated the effects of mast cell-derived histamine, serotonin, tumour necrosis factor (TNF)-α and tryptase on chemokine release from dermal fibroblasts.

METHODS

Human mast cells (HMC-1) were investigated for histamine release and cytokine production after ionizing radiation using enzyme-linked immunosorbent assay (ELISA) and flow cytometry. Receptor expression on human fetal foreskin fibroblasts (HFFF2) and human adult skin fibroblasts (HDFa) was examined by flow cytometry. Chemokine mRNA and protein expression were analyzed by gene array and ELISA, respectively.

RESULTS

Ionizing radiation significantly increased histamine release and cytokine expression by HMC-1 cells. Receptors for histamine, serotonin, TNF-α and tryptase were detected both in HFFF2 and in HDFa cells. Dermal fibroblasts constitutively expressed distinct sets of chemokine mRNA. Mast cell mediators differentially affected the release of chemokines CCL8, CCL13, CXCL4 and CXCL6 by fibroblasts.

CONCLUSIONS

Our data suggest that radiation-induced mast cell mediators have a tremendous impact on inflammatory cell recruitment into irradiated skin. We postulate the activation of mast cells to be an initial key event in the cutaneous radiation reaction, which might offer promising targets for treatment of both normal tissue side effects in radiation therapy and radiation injuries.

Depression, selective serotonin reuptake inhibitors, and osteoporosis

An increasing number of studies suggest an association between depression and osteoporosis. In a mouse model, depression induces bone loss, mediated by brain-to-bone sympathetic signaling. Depression and bone antianabolic sympathetic tone are alleviated by increasing central serotonin (5-hydroxytryptamine, 5-HT) levels. However, selective serotonin reuptake inhibitors (SSRIs), the first-line antidepressants, increase extracellular 5-HT levels but have deleterious skeletal effects. The skeletal serotonergic system consists of 5-HT receptors and the 5-HT transporter (5-HTT) in osteoblasts and osteocytes. 5-HTT is a transmembrane protein targeted by SSRIs. 5-HT restrains osteoblastic activity, thus leading to bone loss. Apparently, the negative skeletal effects of the peripheral SSRI-induced increase in 5-HT outweighs the skeletal benefits resulting from the enhanced central 5-HT antidepressant and antisympathetic activity. Overall, major depression appears as an important risk factor for osteoporosis. However, antidepressants, mainly SSRIs, should be evaluated in view of the causal relationship between depression and bone loss, and vis-à-vis their skeletal adverse effects. Patients with depressive disorders should undergo a routine skeletal evaluation and receive timely antiosteoporotic therapy, especially when SSRI treatment is prescribed.

Laxative abuse: epidemiology, diagnosis and management

Laxatives have been used for health purposes for over 2000 years, and for much of that time abuse or misuse of laxatives has occurred. Individuals who abuse laxatives can generally be categorized as falling into one of four groups. By far the largest group is made up of individuals suffering from an eating disorder such as anorexia or bulimia nervosa. The prevalence of laxative abuse has been reported to range from approximately 10% to 60% of individuals in this group. The second group consists of individuals who are generally middle aged or older who begin using laxatives when constipated but continue to overuse them. This pattern may be promulgated on certain beliefs that daily bowel movements are necessary for good health. The third group includes individuals engaged in certain types of athletic training, including sports with set weight limits. The fourth group contains surreptitious laxative abusers who use the drugs to cause factitious diarrhoea and may have a factitious disorder. Normal bowel function consists of the absorption of nutrients, electrolytes and water from the gut. Most nutrients are absorbed in the small intestine, while the large bowel absorbs primarily water. There are several types of laxatives available, including stimulant agents, saline and osmotic products, bulking agents and surfactants. The most frequently abused group of laxatives are of the stimulant class. This may be related to the quick action of stimulants, particularly in individuals with eating disorders as they may erroneously believe that they can avoid the absorption of calories via the resulting diarrhoea. Medical problems associated with laxative abuse include electrolyte and acid/base changes that can involve the renal and cardiovascular systems and may become life threatening. The renin-aldosterone system becomes activated due to the loss of fluid, which leads to oedema and acute weight gain when the laxative is discontinued. This can result in reinforcing further laxative abuse when a patient feels bloated and has gained weight. Treatment begins with a high level of suspicion, particularly when a patient presents with alternating diarrhoea and constipation as well as other gastrointestinal complaints. Checking serum electrolytes and the acid/base status can identify individuals who may need medical stabilization and confirm the severity of the abuse. The first step in treating laxative misuse once it is identified is to determine what may be promoting the behaviour, such as an eating disorder or use based on misinformation regarding what constitutes a healthy bowel habit. The first intervention would be to stop the stimulant laxatives and replace them with fibre/osmotic supplements utilized to establish normal bowel movements. Education and further treatment may be required to maintain a healthy bowel programme. In the case of an eating disorder, referral for psychiatric treatment is essential to lessen the reliance on laxatives as a method to alter weight and shape.

Do fluctuations in ovarian hormones affect gastrointestinal symptoms in women with irritable bowel syndrome?

BACKGROUND

An increase in gastrointestinal (GI) symptoms, including bowel discomfort, abdominal pain/discomfort, bloating, and alterations in bowel patterns, has been reported during premenses and menses menstrual cycle phases and the perimenopause period in women with and without irritable bowel syndrome (IBS).

OBJECTIVE

This article reviews the literature related to one possible physiological mechanism-declining or low ovarian hormone levels--that may underlie the occurrence or exacerbations of abdominal pain/discomfort at times of low ovarian hormones (menses, menopause) in women with or without IBS.

METHODS

To identify English-only review and data-based articles, PubMed was searched between January 1980 and September 2008 using the following terms: irritable bowel syndrome, functional gastrointestinal disorders, gastrointestinal motility, immune, pain, hyperalgesia, menstrual cycle, menopause, pregnancy, estrogen, estradiol (E(2)), and progesterone. Studies in animals and in humans were included; drug trials were excluded.

RESULTS

From our review of the literature, 18 papers were identified that were related either to the mechanisms accounting for menstrual cycle fluctuations (n = 12) or to the impact of menopausal status on symptoms of IBS (n = 6). One study reported that visceral pain sensitivity was significantly higher during menses than at other menstrual cycle phases in women with IBS (P < 0.05). Other menstrual cycle phase-linked symptoms, dysmenorrheal symptoms (cramping pain) in particular, were more intense in women with IBS. Animal studies have shed some light on the relationship of ovarian hormones to GI sensorimotor function.

CONCLUSION

The increase in GI symptoms around the time of menses and early menopause occurs at times of declining or low ovarian hormones, suggesting that estrogen and progesterone withdrawal may contribute either directly or indirectly. This review highlights the need for confirmatory preclinical and clinical studies to unravel the role of ovarian hormones in women with IBS.

IBS: An epigenetic perspective

IBS is a common and debilitating disorder. The pathophysiology of IBS is poorly understood and is currently viewed as a biopsychosocial disorder with symptoms mediated via the brain-gut axis. Epidemiological studies of IBS point to risk factors such as familial clustering, sexual abuse and other forms of childhood trauma, low birth weight and gastrointestinal infection. Epigenetics focuses on the complex and dynamic interaction between the DNA sequence, DNA modifications and environmental factors, all of which combine to produce the phenotype. Studies in animal models of early stress and in humans who have experienced childhood trauma or abuse suggest that these events can lead to long-lasting epigenetic changes in the glucocorticoid receptor gene brought about by hypermethylation of a key regulatory component. Animal studies also indicate that the microbiota has a pivotal role in programming the core stress system, the hypothalamic-pituitary-adrenal axis and the immune system through epigenetic mechanisms. In this Perspectives, an epigenetic model of IBS is presented that incorporates many of the current findings regarding IBS, including proinflammatory markers, neuroendocrine alterations and links with both psychosocial stress and stress related to infection. We conclude that applying epigenetic methodology to this common and disabling disorder may help unravel its complex pathophysiology and lead to more effective treatments.

Tegaserod and the risk of cardiovascular ischemic events: an observational cohort study

OBJECTIVES

Tegaserod, a partial 5-HT(4) agonist previously approved for treatment of irritable bowel syndrome with constipation and chronic idiopathic constipation, was suspended from US marketing in 2007, based on pooled clinical trial results which contained a signal suggesting increased risk of cardiovascular ischemic events (CVIEs). We sought to evaluate whether there was an association between tegaserod and CVIE in a setting of routine clinical practice.

METHODS

This was a matched cohort study conducted within a large US health insurance database, involving 52 229 patients who initiated tegaserod and 52 229 patients with similar characteristics who did not initiate tegaserod. Participants were followed for up to 6 months for the occurrence of CVIE (myocardial infarction, acute coronary syndrome, coronary revascularization, and stroke). Outcomes were identified using insurance claims and were confirmed by review of medical records. We conducted as-matched analyses providing hazard ratios (HRs) along with 95% confidence intervals (95% CI) and as-treated analyses accounting for changes in dispensed therapy.

RESULTS

There was no increased risk of CVIE associated with tegaserod treatment. The as-matched association between tegaserod and ischemic cardiovascular outcomes (HR = 0.95, 95% CI 0.73-1.23) and stroke (HR = 0.90, 95% CI 0.46-1.77) did not change substantially in the as-treated analyses (cardiovascular relative risk [RR] = 1.14, 95% CI 0.83-1.56; stroke: RR = 1.09, 95% CI = 0.49-2.02). The results were largely unaffected by adjustment for characteristics or subgroup analyses.

CONCLUSION

In this observational study of tegaserod use, we found no evidence for an increased risk of CVIE in tegaserod users.

Hexane extract of Poncirus trifoliata (L.) Raf. stimulates the motility of rat distal colon

AIM OF THE STUDY

Poncirus trifoliata (L.) Raf. (Rutaceae, PT) has been commonly used for treating gastrointestinal (GI) disorders in Korean traditional medicine, but its pharmacological roles in the regulation of colonic motility have not been clarified. This study investigated the regulatory effects of PT on the colonic motility.

MATERIALS AND METHODS

Immature fruits of PT were sequentially partitioned with MeOH, n-hexane, CHCl(3), EtOAc, n-BuOH and H(2)O, and the effects of PT extracts on the contractility of colonic strips and colonic luminal transit in rats were measured in vitro and in vivo, respectively.

RESULTS

Among six different extracts, only hexane extract of PT (PTHE) dose-dependently increased the low frequency contraction of longitudinal muscle in distal colonic strips, and the ED(50) value was revealed to be 0.71 microg/ml. The contractile patterns induced by PTHE were remarkably different from those caused by acetylcholine (ACh) and serotonin (5-HT). The stimulatory effects of PTHE on the whole distal colonic strips were more prominent than on the mucosa/submucosa-denuded segments. The M(2) receptor-preferring, methoctramine (0.5 microM), and M(3) receptor-preferring antagonist, 4-DAMP (0.5 microM) significantly blocked the PTHE (1 microg/ml)-induced contraction of distal colon longitudinal muscles, whereas the 5-HT receptor antagonists (1.0 microM, alone or in combination) selective for 5-HT(3) (ondansetron), 5-HT(4) (GR113808) and 5-HT(1, 2, 5-7) (methysergide) receptors did not change the PTHE (1 microg/ml)-induced contractility of distal colon longitudinal muscles. SNAP (0.1mM), a NO donor, enhanced the stimulatory effects of PTHE on the longitudinal muscle of distal colon, but l-NAME (0.1mM), a NO synthesis inhibitor, had no effects. PTHE (10-100mg/kg) caused a dose-dependent increase of colonic luminal transit.

CONCLUSIONS

Collectively, these findings suggest that PTHE specifically acts on the longitudinal muscle of distal colon in rats, and these stimulatory effects are likely mediated, at least, by activation of acetylcholinergic M(2) and M(3) receptors.

[Irritable bowel syndrome: dietary and pharmacological therapeutic options]

In irritable bowel syndrome, the main objectives of the treatment are the relief of abdominal pain then the improvement of bowel disturbances. Spasmolytic agents, or clays remain routinely the first line pharmacological options. The efficacy of dietary recommendations is not validated in most of the cases while dietary fibers, mainly insoluble fibers, may even worsen abdominal discomfort. In C-IBS, osmotic laxatives or macrogol are effective to improve colonic transit while loperamide and also colestyramine can be prescribed to reduce the number of stools of D-IBS patients. When the first line treatment fails to improve symptoms, antidepressants (tricyclic rather than SSRs) can be prescribed at lower doses than that recommended for depression. In meta-analysis, the odds ratio for pain relief varies from 2 to 4 and strongly depends on the patient's compliance to the treatment. Probiotics, pregabalin and even antibiotics (i.e neomycin, metronidazole or rifaximin), are possible new therapeutic options. Few clinical trials suggest that ramosetron (a new 5HT3 antagonist), octreotide, melatonin, or lidocain could be also discussed in the future. A non pharmacological therapeutic approach has to be considered, particularly in patients with severe symptoms, in combination with pharmacological treatment.

The effect of mosapride citrate on constipation in patients with diabetes

OBJECTIVE

Constipation is one of the most common gastrointestinal complications suspected to degrade the quality of life in diabetic patients. Mosapride citrate is a novel selective 5-HT4 receptor agonist, which enhances gastric emptying and motility in the upper gastrointestinal tract facilitating acetylcholine release from the enteric cholinergic neurons. Since the receptors of 5-HT4 have been recently found in the lower intestine including the rectum in humans, we tested if mosapride improves constipation in diabetic patients.

PATIENTS AND METHODS

Diabetic patients with constipation were treated with mosapride citrate (15 mg/day, n=20) or domperidone (30 mg/day, n=12) as controls for 8 weeks. Bowel frequency was monitored and gastrointestinal symptoms were evaluated by Gastrointestinal Symptoms Rating Scale (GSRS).

RESULTS

Administration of mosapride resulted in increased bowel frequency after 4 and 8 weeks of administration, while no change was seen in the control group. Mosapride increased bowel frequency in even patients with diabetic polyneuropathy. Mosapride improved reflux and constipation evaluated by GSRS. As previously reported, glycemic control also improved by mosapride in these patients.

CONCLUSIONS

Administration of mosapride increased bowel frequency and ameliorated symptoms of reflux and constipation possibly stimulating the lower intestine. Given that mosapride has those beneficial aspects, it may be a useful prokinetic agent in treating diabetic patients with constipation.

Advances in understanding the pathogenesis of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a highly prevalent gastrointestinal motility disorder characterized by abdominal discomfort/pain associated with altered bowel habits. At present, the pathophysiology of IBS is still unknown. Genetic factors, psychosocial factors, and changes in gastrointestinal motility and visceral hypersensitivity are traditionally thought to play a crucial role in symptom generation in IBS. Recent studies have identified new additional factors (such as dysregulation of the brain-gut axis, gastrointestinal infection, and activation of mast cells in the intestinal mucosa with consequent release of bioactive substances) that are correlated with the pathogenesis of IBS. In this article, we will review the recent advances in the research on the pathogenesis of IBS.

Tryptophan degradation in irritable bowel syndrome: evidence of indoleamine 2,3-dioxygenase activation in a male cohort

Background

Irritable bowel syndrome (IBS) is a common disorder that affects 10–15% of the population. Although characterised by a lack of reliable biological markers, the disease state is increasingly viewed as a disorder of the brain-gut axis. In particular, accumulating evidence points to the involvement of both the central and peripheral serotonergic systems in disease symptomatology. Furthermore, altered tryptophan metabolism and indoleamine 2,3-dioxygenase (IDO) activity are hallmarks of many stress-related disorders. The kynurenine pathway of tryptophan degradation may serve to link these findings to the low level immune activation recently described in IBS. In this study, we investigated tryptophan degradation in a male IBS cohort (n = 10) and control subjects (n = 26).

Methods

Plasma samples were obtained from patients and healthy controls. Tryptophan and its metabolites were measured by high performance liquid chromatography (HPLC) and neopterin, a sensitive marker of immune activation, was measured using a commercially available ELISA assay.

Results

Both kynurenine levels and the kynurenine:tryptophan ratio were significantly increased in the IBS cohort compared with healthy controls. Neopterin was also increased in the IBS subjects and the concentration of the neuroprotective metabolite kynurenic acid was decreased, as was the kynurenic acid:kynurenine ratio.

Conclusion

These findings suggest that the activity of IDO, the immunoresponsive enzyme which is responsible for the degradation of tryptophan along this pathway, is enhanced in IBS patients relative to controls. This study provides novel evidence for an immune-mediated degradation of tryptophan in a male IBS population and identifies the kynurenine pathway as a potential source of biomarkers in this debilitating condition.

[Neurological and psychiatric aspects of some gastrointestinal diseases]

The gastrointestinal tract is controlled by the independent enteric nervous system. It is also closely connected to the central nervous system, and bi-directional communication exists between them. The communication involves neural pathways as well as immune and endocrine mechanisms. The brain-gut axis plays a prominent role in the modulation of gut functions. Signals from different sources (e.g. sound, sight, smell, somatic and visceral sensations, pain) reach the brain. These inputs are modified by memory, cognition and affective mechanisms and integrated within the neural circuits of the central nervous system, spinal cord, autonomic and enteral nervous systems. These inputs can have physiologic effects, such as changes in motility, secretion, immune function, and blood flow to the gastrointestinal tract. One of the most important neurotransmitters is serotonin that plays a key role in the pathogenesis of the most common chronic functional gastrointestinal disorder: the irritable bowel syndrome. It is a biopsychosocial disease, resulting from the dysregulation of the brain-gut axis. Endogenous pain facilitation rather than inhibition, pathologic gradation of visceral perception and reduced threshold for pain are all evident in these patients. Abuse history is common in their anamnesis. Exaggerated conscientiousness, perfectionism, oversensitivity, feeling of deficiency in effectiveness, and higher demand for social parity, neuroticism and alexithymia have been detected among their constant personality features. Females are also characterized by gender role conflict and low assertiveness. Antidepressants and psychotherapy have important roles in their treatment. Also patients with inflammatory bowel disease are characterized by neuroticism and alexithymia and altered mother-child attachment is often described in their anamnesis. Autonomic neuropathy is a frequent and early neurological complication. Reflux disease and obstructive sleep apnea mutually generate each other and their severities significantly correlate. In the celiac disease the most common neurological manifestations are ataxia, peripheral neuropathy and myopathy. Up to 85% of patients with histologically proven coeliac disease have no gastrointestinal symptoms; consequently, measurement of antigliadin antibody titre is therefore vital in all cases of idiopathic ataxia. Complete resolution of neurological symptoms is the result of gluten-free diet.

Effects of ghrelin on interdigestive contractions of the rat gastrointestinal tract

Ghrelin causes interdigestive contractions of the stomach in rats. However, it remains unknown whether ghrelin causes interdigestive contractions in the small intestine. Four strain gauge transducers were implanted on the antrum, duodenum, proximal and distal jejunum. After an overnight fast, gastrointestinal (GI) contractions were recorded in freely moving conscious rats. Spontaneous phase III-like contractions were observed at every 13-16 min in rat GI tract. The fasted motor patterns were replaced by the fed motor pattern immediately after food intake. Two minutes after finishing the spontaneous phase III-like contractions in the antrum, acyl ghrelin (0.8, 2.4 and 8.0 μg/kg per min) was continuously infused for 30 min. Three-five minutes after the starting ghrelin infusion, augmented phase III-like contractions were observed at the antrum, duodenum, and jejunum. Ghrelin infusion (0.8, 2.4 and 8.0 μg/kg per min) significantly increased motility index of phase III-like contractions at the antrum and jejunum in a dose dependent manner, compared to that of saline injection. Thus, it is likely that exogenously administered ghrelin causes phase III-like contraction at the antrum, which migrates to the duodenum and jejunum. The possible role of 5-HT, in addition to ghrelin, in mediating intestinal migrating motor complex (MMC), is discussed.

Changes in salivary physiological stress markers induced by muscle stretching in patients with irritable bowel syndrome

Background

Psychophysiological processing has been reported to play a crucial role in irritable bowel syndrome (IBS) but there has been no report on modulation of the stress marker chromogranin A (CgA) resulting from muscle stretching. We hypothesized that abdominal muscle stretching as a passive operation would have a beneficial effect on a biochemical index of the activity of the sympathetic/adrenomedullary system (salivary CgA) and anxiety.

Methods

Fifteen control and eighteen untreated IBS subjects underwent experimental abdominal muscle stretching for 4 min. Subjects relaxed in a supine position with their knees fully flexed while their pelvic and trunk rotation was passively and slowly moved from 0 degrees of abdominal rotation to about 90 degrees or the point where the subject reported feeling discomfort.

Changes in the Gastrointestinal Symptoms Rating Scale (GSRS), State Trait Anxiety Inventory (STAI), Self-rating Depression Scale (SDS), ordinate scale and salivary CgA levels were compared between controls and IBS subjects before and after stretching. A three-factor analysis of variance (ANOVA) with period (before vs. after) as the within-subject factor and group (IBS vs. Control), and sex (men vs. female) as the between-subject factors was carried out on salivary CgA.

Results

CgA showed significant interactions between period and groups (F[1, 31] = 4.89, p = 0.03), and between groups and sex (F[1, 31] = 4.73, p = 0.03). Interactions between period and sex of CgA secretion were not shown (F[1, 3] = 2.60, p = 0.12). At the baseline, salivary CgA in IBS subjects (36.7 ± 5.9 pmol/mg) was significantly higher than in controls (19.9 ± 5.5 pmol/mg, p < 0.05). After the stretching, salivary CgA significantly decreased in the IBS group (25.5 ± 4.5 pmol/mg), and this value did not differ from that in controls (18.6 ± 3.9 pmol/mg).

Conclusion

Our results suggest the possibility of improving IBS pathophysiology by passive abdominal muscle stretching as indicated by CgA, a biochemical index of the activity of the sympathetic/adrenomedullary system.