Melatonin improves abdominal pain in irritable bowel syndrome patients who have sleep disturbances: a randomised, double blind, placebo controlled study

Therapeutic applications of melatonin in disorders related to the gastrointestinal tract and control of appetite

Most animals have large amounts of the special substance melatonin, which is controlled by the light/dark cycle in the suprachiasmatic nucleus. According to what is now understood, the gastrointestinal tract (GIT) and other areas of the body are sites of melatonin production. According to recent studies, the GIT and adjacent organs depend critically on a massive amount of melatonin. Not unexpectedly, melatonin's many biological properties, such as its antioxidant, anti-inflammatory, pro-apoptotic, anti-proliferative, anti-metastasis, and antiangiogenic properties, have drawn the attention of researchers more and more. Because melatonin is an antioxidant, it produces a lot of secretions in the GIT's mucus and saliva, which shields cells from damage and promotes the development of certain GIT-related disorders. Melatonin's ability to alter cellular behavior in the GIT and other associated organs, such as the liver and pancreas, is another way that it functions. This behavior alters the secretory and metabolic activities of these cells. In this review, we attempted to shed fresh light on the many roles that melatonin plays in the various regions of the gastrointestinal tract by focusing on its activities for the first time.

Melatonin as a Mediator of the Gut Microbiota-Host Interaction: Implications for Health and Disease

In recent years, the role played by melatonin on the gut microbiota has gained increasingly greater attention. Additionally, the gut microbiota has been proposed as an alternative source of melatonin, suggesting that this antioxidant indoleamine could act as a sort of messenger between the gut microbiota and the host. This review analyses the available scientific literature about possible mechanisms involved in this mediating role, highlighting its antioxidant effects and influence on this interaction. In addition, we also review the available knowledge on the effects of melatonin on gut microbiota composition, as well as its ability to alleviate dysbiosis related to sleep deprivation or chronodisruptive conditions. The melatonin-gut microbiota relationship has also been discussed in terms of its role in the development of different disorders, from inflammatory or metabolic disorders to psychiatric and neurological conditions, also considering oxidative stress and the reactive oxygen species-scavenging properties of melatonin as the main factors mediating this relationship.

Sleep Disorders and Chronic Pain Syndromes in the Pediatric Population

Sleep problems are widespread in children and adolescents suffering from chronic pain disorders. Sleep loss intensifies the experience of pain and is detrimental to the budding self-efficacy of a young individual with limitless horizons. Addressing sleep disorders may prevent the chronification of pain and prevent adverse health outcomes, such as functional impairment, psychiatric comorbidities and overall poor quality of life. This review will explore the cyclical nature between sleep, pain and mood, as well as the functional impact of this relationship on children and adolescents. There will be a discussion about sleep assessment and diagnostic testing, followed by a description of sleep disturbances found in specific pain conditions, ranging from headache, musculoskeletal/abdominal pain, to rheumatologic disorders. Finally, there will be a brief review of pharmacologic and behavioral interventions designed to improve sleep quality, and when possible, to alleviate pain.

Circadian rhythms in colonic function

A rhythmic expression of clock genes occurs within the cells of multiple organs and tissues throughout the body, termed "peripheral clocks." Peripheral clocks are subject to entrainment by a multitude of factors, many of which are directly or indirectly controlled by the light-entrainable clock located in the suprachiasmatic nucleus of the hypothalamus. Peripheral clocks occur in the gastrointestinal tract, notably the epithelia whose functions include regulation of absorption, permeability, and secretion of hormones; and in the myenteric plexus, which is the intrinsic neural network principally responsible for the coordination of muscular activity in the gut. This review focuses on the physiological circadian variation of major colonic functions and their entraining mechanisms, including colonic motility, absorption, hormone secretion, permeability, and pain signalling. Pathophysiological states such as irritable bowel syndrome and ulcerative colitis and their interactions with circadian rhythmicity are also described. Finally, the classic circadian hormone melatonin is discussed, which is expressed in the gut in greater quantities than the pineal gland, and whose exogenous use has been of therapeutic interest in treating colonic pathophysiological states, including those exacerbated by chronic circadian disruption.

Glucocorticoid receptor-mediated Nr1d1 chromatin circadian misalignment in stress-induced irritable bowel syndrome

Stress-elevated glucocorticoids cause circadian disturbances and gut-brain axis (GBA) disorders, including irritable bowel syndrome (IBS). We hypothesized that the glucocorticoid receptor (GR/NR3C1) might cause chromatin circadian misalignment in the colon epithelium. We observed significantly decreased core circadian gene Nr1d1 in water avoidance stressed (WAS) BALB/c colon epithelium, like in IBS patients. WAS decreased GR binding at the Nr1d1 promoter E-box (enhancer box), and GR could suppress Nr1d1 via this site. Stress also altered GR binding at the E-box sites along the Ikzf3-Nr1d1 chromatin and remodeled circadian chromatin 3D structures, including Ikzf3-Nr1d1 super-enhancer, Dbp, and Npas2. Intestinal deletion of Nr3c1 specifically abolished these stress-induced transcriptional alternations relevant to IBS phenotypes in BALB/c mice. GR mediated Ikzf3-Nr1d1 chromatin disease related circadian misalignment in stress-induced IBS animal model. This animal model dataset suggests that regulatory SNPs of human IKZF3-NR1D1 transcription through conserved chromatin looping have translational potential based on the GR-mediated circadian-stress crosstalk.

Microbial-Derived Tryptophan Metabolites and Their Role in Neurological Disease: Anthranilic Acid and Anthranilic Acid Derivatives

The gut microbiome provides the host access to otherwise indigestible nutrients, which are often further metabolized by the microbiome into bioactive components. The gut microbiome can also shift the balance of host-produced compounds, which may alter host health. One precursor to bioactive metabolites is the essential aromatic amino acid tryptophan. Tryptophan is mostly shunted into the kynurenine pathway but is also the primary metabolite for serotonin production and the bacterial indole pathway. Balance between tryptophan-derived bioactive metabolites is crucial for neurological homeostasis and metabolic imbalance can trigger or exacerbate neurological diseases. Alzheimer's, depression, and schizophrenia have been linked to diverging levels of tryptophan-derived anthranilic, kynurenic, and quinolinic acid. Anthranilic acid from collective microbiome metabolism plays a complex but important role in systemic host health. Although anthranilic acid and its metabolic products are of great importance for host-microbe interaction in neurological health, literature examining the mechanistic relationships between microbial production, host regulation, and neurological diseases is scarce and at times conflicting. This narrative review provides an overview of the current understanding of anthranilic acid's role in neurological health and disease, with particular focus on the contribution of the gut microbiome, the gut-brain axis, and the involvement of the three major tryptophan pathways.

Protective and therapeutic potential of melatonin against intestinal diseases: updated review of current data based on molecular mechanisms

INTRODUCTION

Intestinal diseases, a leading global cause of mortality and morbidity, carry a substantial socioeconomic burden. Small and large intestines play pivotal roles in gastrointestinal physiology and food digestion. Pathological conditions, such as gut dysbiosis, inflammation, cancer, therapy-related complications, ulcers, and ischemia, necessitate the urgent exploration of safe and effective complementary therapeutic strategies for optimal intestinal health.

AREAS COVERED

This article evaluates the potential therapeutic effects of melatonin, a molecule with a wide range of physiological actions, on intestinal diseases including inflammatory bowel disease, irritable bowel syndrome, colon cancer, gastric/duodenal ulcers and other intestinal disorders.

EXPERT OPINION

Due to anti-inflammatory and antioxidant properties as well as various biological actions, melatonin could be a therapeutic option for improving digestive disorders. However, more researches are needed to fully understand the potential benefits and risks of using melatonin for digestive disorders.

The effect of melatonin on irritable bowel syndrome patients with and without sleep disorders: a randomized double-blinded placebo-controlled trial study

BACKGROUND

Irritable bowel syndrome (IBS) is one of the world's most common gastrointestinal (GI) disorders, and current treatments do not meet patients' demands. This study aimed to investigate melatonin's therapeutic effects on IBS score, GI symptoms, quality of life, and sleep parameters in both groups of IBS patients with and without sleep disorders.

METHODS

In this randomized double-blinded placebo-controlled trial study, 136 patients with a diagnosis of IBS based on ROME IV criteria were enrolled and then divided into two groups respecting having sleep disorders or not. Patients of each group were randomized in a 1:1 ratio to receive melatonin 6 mg daily (3 mg fasting and 3 mg at bedtime) for 2 months (8 weeks). Blocked randomization was used in this process. All patients were evaluated both at the beginning and the end of the trial regarding IBS score, GI symptoms, quality of life, and sleep parameters through valid questionnaires.

RESULTS

In both groups of patients with and without sleep disorders, a significant improvement was observed in IBS score and GI symptoms, including the severity and the frequency of abdominal pain, the severity of abdominal bloating, satisfaction with bowel habits, disease's impact on patient's life, and stool consistency; however, there was no significant improvement in the frequency of defecations per week. In patients with sleep disorders, significant improvement in sleep parameters, including subjective sleep quality, sleep latency, sleep duration, sleep efficiency, and daytime dysfunction, was observed, while in patients without sleep disorders, there was no significant improvement in sleep parameters. In addition, quality-of-life improvement was observed in a significant number of melatonin recipients compared to placebo in both groups of patients.

CONCLUSION

Melatonin can be considered an effective treatment for improving IBS score, GI symptoms, and quality of life in IBS patients with and without sleep disorders. It is also effective to improve sleep parameters in IBS patients with sleep disorders.

TRIAL REGISTRATION

This study has been registered to the Iranian Registry of Clinical Trials (IRCT) with the approval number IRCT20220104053626N2 on the date of 13/02/2022.

The association between self-reported sleep problems, infection, and antibiotic use in patients in general practice

Objectives

There is emerging evidence that sleep problems and short sleep duration increase the risk of infection. We aimed to assess whether chronic insomnia disorder, chronic sleep problems, sleep duration and circadian preference based on self-report were associated with risk of infections and antibiotic use among patients visiting their general practitioner (GP).

Methods

We conducted a cross-sectional study of 1,848 unselected patients in Norway visiting their GP during 2020.The patients completed a one-page questionnaire while waiting for the consultation, that included the validated Bergen Insomnia Scale (BIS), questions on self-assessed sleep problem, sleep duration and circadian preference and whether they have had any infections or used antibiotics in the last 3 months. Relative risks (RR) were estimated using modified Poisson regression models.

Results

The risk of infection was 27% (95% CI RR 1.11-1.46) and 44% higher (95% CI 1.12-1.84) in patients sleeping < 6 h and >9 h, respectively, compared to those sleeping 7-8 h. The risk was also increased in patients with chronic insomnia disorder or a chronic sleep problem. For antibiotic use, the risk was higher for patients sleeping < 6 h, and for those with chronic insomnia disorder or a chronic sleep problem.

Conclusions

Among patients visiting their GP, short sleep duration, chronic insomnia and chronic sleep problem based on self-report were associated with higher prevalence of infection and antibiotic use. These findings support the notion of a strong association between sleep and infection.

The efficacy of exogenous melatonin supplement in ameliorating irritable bowel syndrome severity: A meta-analysis of randomized controlled trials

BACKGROUND

Irritable bowel syndrome (IBS) was found in 11% of the general population worldwide. The current pharmacologic management of IBS was unsatisfactory, and it was accompanied by a number of adverse events. Melatonin was found to play an important role in gastrointestinal smooth muscle motility. Dysregulation of endogenous melatonin secretion has been found in IBS patients. Exogenous melatonin supplement has become one alternative treatment for IBS, but the evidence is inconclusive. The current meta-analysis sought to determine the efficacy of exogenous melatonin supplement in improving IBS severity in IBS patients.

METHODS

We included randomized controlled trials (RCTs) that investigated the efficacy of exogenous melatonin supplement in ameliorating IBS severity in IBS patients. This meta-analysis was conducted using a random effects model. The primary target outcomes were changes in IBS severity associated with melatonin or placebo.

RESULTS

This meta-analysis of 4 RCTs and 115 participants revealed that exogenous melatonin supplement was associated with significantly better improvement in overall IBS severity than placebo (k = 4, Hedges' g = 0.746, 95% confidence intervals = 0.401-1.091, p < 0.001). The subgroup without concurrent medication had the same result (p < 0.001). In addition, exogenous melatonin supplement was also associated with significantly better improvement in IBS pain severity (p < 0.001) and quality of life (p = 0.007) than placebo, but not in abdominal distension (p = 0.111) or sleep quality (p = 0.142). Finally, melatonin was associated with similar safety profiles with placebo.

CONCLUSION

This meta-analysis provides evidence for the use of exogenous melatonin in IBS patients to ameliorate overall IBS severity, IBS pain severity, and quality of life.

TRIAL REGISTRATION

PROSPERO CRD42021269451.

Randomised controlled trial of melatonin for paediatric functional abdominal pain disorders

AIM

Melatonin seems to have a positive impact on the brain-gut axis and many direct and indirect effects on the gastrointestinal tract. This trial aimed at assessing the efficacy of melatonin combined with Lactobacillus Rhamnosus GG given in the treatment of paediatric patients with functional abdominal pain disorders.

METHODS

Forty-two patients aged 4-18 years old who fulfilled the Rome IV Diagnostic Criteria for functional abdominal pain disorders were enrolled. Melatonin 3 or 5 mg in combination with Lactobacillus Rhamnosus GG (group 1, n = 22) or a placebo in combination with Lactobacillus Rhamnosus GG (control group, n = 20) were taken in the evening for a period of 4 weeks. The study duration was 12 weeks. The primary study endpoint was represented by clinical improvement at week 12 - defined as at least a 50% reduction in mean abdominal pain index (API) from baseline to week 12.

RESULTS

The mean API was reduced by more than 50% between T0 and T2 in the group of children treated with melatonin. However, the difference in the distributions of the variations of the scores between the two groups was not significant between T0 and T2 (P = 0.082), while it was significant between T0 and T1 (P = 0.001). Similar results were obtained by analysing the API variables 'weekly frequency of pain' (item 1) and 'perceived intensity of pain' (item 4) individually.

CONCLUSIONS

This is the first study to investigate the role of the combination of melatonin and Lactobacillus Rhamnosus GG in the treatment of children with functional abdominal pain disorders. Melatonin combined with Lactobacillus Rhamnosus GG can be considered a therapeutic option for these conditions in children.

Analgesic efficacy of sleep-promoting pharmacotherapy in patients with chronic pain: a systematic review and meta-analysis

Dysregulation of sleep heightens pain sensitivity and may contribute to pain chronification. Interventions which consolidate and lengthen sleep have the potential to improve pain control. The main objective of this systematic review was to examine the effects of sleep-promoting pharmacotherapy on pain intensity in patients with chronic pain. Multiple electronic databases were searched from inception to January 2022 to identify relevant randomized controlled trials (RCTs). Two independent reviewers screened titles, abstracts, and full-text articles; extracted data; and assessed risk of bias for each included study. The GRADE approach was used to determine the strength of evidence. The search identified 624 articles. After full-text screening, 10 RCTs (n = 574 randomized participants) involving 3 pharmacologic interventions (melatonin, zopiclone, and eszopiclone) and 7 different chronic pain populations were included. Minimum clinically significant pain reduction ≥30% was reported in 4 studies. There is low-quality evidence (downgraded due to inconsistency and imprecision) that 2 to 8 weeks treatment with a sleep-promoting medication alone or in combination with an analgesic (6 trials, n = 397) decreases pain intensity compared with placebo or the same analgesic treatment alone (SMD -0.58 [95% confidence interval -1.00, -0.17], P = 0.006). Analyses of associations between changes in sleep and pain outcomes were only provided in 2 articles, with inconsistent findings. Notably, pain-relieving effects were most consistent in melatonin trials. Only 3 studies implemented polysomnography to obtain objective sleep measures. Low-quality evidence indicates that pharmacologic sleep promotion may decrease pain intensity in chronic pain populations. More research is needed to fully understand the influence of sleep-targeting interventions on pain control.

Exploring the Tryptophan Metabolic Pathways in Migraine-Related Mechanisms

Migraine is a complex neurovascular disorder, which causes intense socioeconomic problems worldwide. The pathophysiology of disease is enigmatic; accordingly, therapy is not sufficient. In recent years, migraine research focused on tryptophan, which is metabolized via two main pathways, the serotonin and kynurenine pathways, both of which produce neuroactive molecules that influence pain processing and stress response by disturbing neural and brain hypersensitivity and by interacting with molecules that control vascular and inflammatory actions. Serotonin has a role in trigeminal pain processing, and melatonin, which is another product of this pathway, also has a role in these processes. One of the end products of the kynurenine pathway is kynurenic acid (KYNA), which can decrease the overexpression of migraine-related neuropeptides in experimental conditions. However, the ability of KYNA to cross the blood-brain barrier is minimal, necessitating the development of synthetic analogs with potentially better pharmacokinetic properties to exploit its therapeutic potential. This review summarizes the main translational and clinical findings on tryptophan metabolism and certain neuropeptides, as well as therapeutic options that may be useful in the prevention and treatment of migraine.

The Effects of Cognitive Behavioral Therapy for Insomnia among College Students with Irritable Bowel Syndrome: A Randomized Controlled Trial

The aim of the study was to develop and evaluate cognitive behavioral therapy for insomnia (CBT-I) among college students with irritable bowel syndrome (IBS). We randomly assigned 60 college students with IBS comorbid insomnia to the experimental group who received CBT-I for 90 min once a week for 4 weeks and the control (non-CBT-I) group. Participants completed self-report measures of insomnia severity, pre-sleep arousal, sleep-related dysfunctional cognitions, maladaptive sleep habits, IBS symptom severity and IBS quality of life (QOL) at baseline, after intervention, and at 3-month follow-up. Sleep pattern, GI symptoms during sleep and Interleukin-6 (IL-6) and C-Reaction Protein (CRP) were measured at baseline and after intervention. The experimental group showed significant decreases in insomnia severity, sleep onset latency, total time in bed, pre-sleep arousal, GI symptoms during sleep, sleep-related dysfunctional cognitions, maladaptive sleep habits, and IBS symptom severity, compared with the control group. This group also showed significant increases in sleep efficiency and IBS QOL compared with the control group. No significant differences were observed between the levels of IL-6 and CRP of both groups. CBT-I for college students with comorbid IBS and insomnia was effective in reducing insomnia, IBS symptom severity, and IBS QOL.

Relationship between Neuroticism and Gastrointestinal Symptoms in Irritable Bowel Syndrome: The Mediating Role of Sleep

Background

We aimed to explore the relationship between the sleep and gastrointestinal symptoms in patients with irritable bowel syndrome (IBS) from the perspective of personality factors.

Methods

Overall, 167 patients with IBS- from First Affiliated Hospital of Nanjing Medical University in Jiangsu Province of China in 2019 were included. Gastrointestinal Symptom Score (GIS), Chinese version of Pittsburgh Sleep Quality Index (PSQI) and Eysenck Personality Questionnaire (EPQ) were used to assess gastrointestinal symptoms, sleep and personality. We use mediator variables analyze to explore the relationship between sleep, neurotic personality and gastrointestinal symptoms in IBS patients.

Results

48.5% of IBS patients had sleep disorders. IBS patients with high neuroticism had higher total PSQI scores, longer sleep latency, worse sleep persistence, more nocturnal sleep disturbances and daytime dysfunctions, and more use of sleep medication (P<0.05). Stomach distention, cramping epigastric pain, loss of appetite, and epigastric pain were more prominent in IBS patients with high neuroticism (P<0.05). In addition, neurotic personality was significantly predictive of sleep and some gastrointestinal symptoms, and sleep was a complete mediator of neurotic personality and gastrointestinal symptoms in IBS patients.

Conclusion

High neurotic personality in IBS patients leads to more prominent gastrointestinal symptoms by causing sleep disturbance.

Night shift hormone: How does melatonin affect depression?

Melatonin is the main hormone secreted by the pineal gland that modulates the circadian rhythm and mood. Previous studies have shown the therapeutic effects of melatonin, or its important analogue, agomelatine, on depression. In this review study, we aimed to discuss the potential mechanisms of melatonin involved in the treatment of depression. It was noted that disrupted circadian rhythm can lead to depressive state, and melatonin via regulating circadian rhythm shows a therapeutic effect. It was also noted that melatonin induces antidepressant effects via promoting antioxidant system and neurogenesis, and suppressing oxidative stress, neuroinflammation, and apoptosis. The interaction effect between melatonin or agomelatine and serotonergic signaling has a significant effect on depression. It was noted that the psychotropic effects of agomelatine are induced by the synergistic interaction between melatonin and 5-HT_2C receptors. Agomelatine also interacts with glutamatergic signaling in brain regions involved in regulating mood and circadian rhythm. Interestingly, it was concluded that melatonin exerts both pro- and anti-inflammatory effects, depending on the grade of inflammation. It was suggested that synergistic interaction between melatonin and 5-HT_2C receptors may be able to induce therapeutic effects on other psychiatric disorders. Furthermore, dualistic role of melatonin in regulating inflammation is an important point that can be examined at different levels of inflammation in animal models of depression.

Impact of shift work on irritable bowel syndrome and functional dyspepsia: A meta-analysis

BACKGROUND

The possible association between shift work with irritable bowel syndrome (IBS) and functional dyspepsia (FD) remains controversial. The purpose of the study is to conduct a meta-analysis to explore the potential association between shift work with IBS/FD.

METHODS

We searched relevant observational studies on Medline (PubMed) and Embase until June 30, 2021. Two different investigators extracted data and assessed the quality of each study independently. The meta-analysis was used to evaluate the pooled odds risk (OR) between shift work and IBS/FD.

RESULTS

Eight studies were included ultimately. Shift workers were more likely to suffer from IBS. The OR of shift work was 1.81 (95% confidence interval 1.42; 2.32) with low heterogeneity (P < .05, I2 = 0%) for IBS. However, no evidence of the association was observed between shift work and the risk of FD. The OR of shift work was 0.87 (95% confidence interval 0.62; 1.23) (P > .05) for FD.

CONCLUSIONS

There was a positive association between shift work and IBS. The prevalence of IBS was 81% higher among shift workers than among non-shift workers. Shift work was probably a risk factor for IBS. The low heterogeneity supports the reliability of the results. However, there was no significant association between shift work and FD. The strength of the evidence was limited and further prospective cohort studies were needed.

Circadian Rhythms and Melatonin Metabolism in Patients With Disorders of Gut-Brain Interactions

Circadian rhythms are cyclic patterns of physiological, behavioural and molecular events that occur over a 24-h period. They are controlled by the suprachiasmatic nucleus (SCN), the brain’s master pacemaker which governs peripheral clocks and melatonin release. While circadian systems are endogenous, there are external factors that synchronise the SCN to the ambient environment including light/dark cycles, fasting/fed state, temperature and physical activity. Circadian rhythms also provide internal temporal organisation which ensures that any internal changes that take place are centrally coordinated. Melatonin synchronises peripheral clocks to the external time and circadian rhythms are regulated by gene expression to control physiological function. Synchronisation of the circadian system with the external environment is vital for the health and survival of an organism and as circadian rhythms play a pivotal role in regulating GI physiology, disruption may lead to gastrointestinal (GI) dysfunction. Disorders of gut-brain interactions (DGBIs), also known as functional gastrointestinal disorders (FGIDs), are a group of diseases where patients experience reoccurring gastrointestinal symptoms which cannot be explained by obvious structural abnormalities and include functional dyspepsia (FD) and irritable bowel syndrome (IBS). Food timing impacts on the production of melatonin and given the correlation between food intake and symptom onset reported by patients with DGBIs, chronodisruption may be a feature of these conditions. Recent advances in immunology implicate circadian rhythms in the regulation of immune responses, and DGBI patients report fatigue and disordered sleep, suggesting circadian disruption. Further, melatonin treatment has been demonstrated to improve symptom burden in IBS patients, however, the mechanisms underlying this efficacy are unclear. Given the influence of circadian rhythms on gastrointestinal physiology and the immune system, modulation of these rhythms may be a potential therapeutic option for reducing symptom burden in these patients.

The Therapeutic Effect of Exogenous Melatonin on Depressive Symptoms: A Systematic Review and Meta-Analysis

BACKGROUND

Depression-related mortality and morbidity pose growing public health burdens worldwide. Although the therapeutic effect of exogenous melatonin on depression has been investigated, findings remain inconsistent. We conducted this systematic review and meta-analysis to clarify the effectiveness of melatonin in the treatment of depression, including primary and secondary depression symptoms.

METHODS

We searched the online databases of PubMed, EMBASE, and the Cochrane Library for original studies published up to May 2021. We used STATA 14.0 software to synthesize the results of included studies. To evaluate the effectiveness of melatonin, we calculated the standardized mean differences (SMDs) and 95% confidence intervals (CIs) of depression scores between the melatonin and placebo groups.

RESULTS

Our literature search returned 754 publications, among which 19 studies with 1,178 patients (715 women, 463 men; mean age: 56.77 years) met inclusion criteria. Melatonin dosages ranged from 2 to 25 mg per day; treatment durations were between 10 days and 3.5 years. Our synthesized results showed that melatonin was not found significantly beneficial for alleviating depressive symptoms (SMD = -0.17, 95% CI = [-0.38, 0.05]). Subgroup analysis demonstrated that the decrease in depression scores measured with the Beck Depression Inventory (BDI) was significant (SMD = -0.52, 95% CI = [-0.73, -0.31]).

CONCLUSIONS

There is very limited evidence for effects of melatonin on depression.

Effect of melatonin supplementation on sleep quality: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The Present study was conducted to systematically review the effect of the melatonin on sleep quality. We summarized evidence from randomized clinical trials (RCTs) that investigated the effects of melatonin on sleep quality as assessed by the Pittsburgh Sleep Quality Index (PSQI) in adults with various diseases.

METHODS

The literature searches of English publications in MEDLINE and EMBASE databases were performed up June 2020. Results were summarized as mean differences (MD) with 95% confidence intervals (CI) using random effects model (DerSimonian-Laird method). Heterogeneity among studies was evaluated by the Cochrane Q test and I-squared (I2). To determine the predefined sources of heterogeneity, subgroup analysis was performed.

RESULTS

Of 2642 papers, 23 RCTs met inclusion criteria. Our results indicated that melatonin had significant effect on sleep quality as assessed by the Pittsburgh Sleep Quality Index (PSQI) (WMD: - 1.24; 95% CI - 1.77, - 0.71, p = 0.000). There was significant heterogeneity between studies (I² = 80.7%, p = 0.000). Subgroup analysis based on health status and kind of intervention were potential between-study heterogeneity. Subgroup analysis based on health status revealed melatonin intervention in subjects with Respiratory diseases (WMD: - 2.20; 95% CI - 2.97, - 1.44, p = 0.000), Metabolic disorders (WMD: - 2.74; 95% CI - 3.48, - 2.00, p = 0.000) and sleep disorders (WMD: - 0.67; 95% CI - 0.98, - 0.37, p = 0.000) has significant effect on sleep quality.

CONCLUSION

We found that the treatment with exogenous melatonin has positive effects on sleep quality as assessed by the Pittsburgh Sleep Quality Index (PSQI) in adult. In adults with respiratory diseases, metabolic disorders, primary sleep disorders, not with mental disorders, neurodegenerative diseases and other diseases.

Omics profiles of fecal and oral microbiota change in irritable bowel syndrome patients with diarrhea and symptom exacerbation

BACKGROUND

Irritable bowel syndrome (IBS) is a disorder of gut-brain interaction, including dysregulation of the hypothalamic-pituitary-adrenal axis with salivary cortisol changes. However, the role of gastrointestinal microbiota during IBS symptom exacerbation remains unclear. We tested the hypothesis that the microbial species, gene transcripts, and chemical composition of fecal and oral samples are altered during the exacerbation of IBS symptoms.

METHODS

Fecal, salivary, and dental plaque samples were collected at baseline from 43 men with IBS with diarrhea (IBS-D) and 40 healthy control (HC) men. Samples in the IBS-D patients were also collected during symptom exacerbation. The composition of the fecal microbiota was determined by analyzing the 16S rRNA gene, RNA-based metatranscriptome, and metabolites in samples from HC and IBS patients with and without symptom exacerbation. Oral samples were also analyzed using omics approaches.

RESULTS

The fecal microbiota during IBS symptom exacerbation exhibited significant differences in the phylogenic pattern and short-chain fatty acid compared with fecal samples during defecation when symptoms were not exacerbated. Although there were no significant differences in the phylogenic pattern of fecal microbiota abundance between HCs and IBS-D patients, significant differences were detected in the expression patterns of bacterial transcriptomes related to butyrate production and neuroendocrine hormones, including tryptophan-serotonin-melatonin synthesis and glutamine/GABA. The composition of plaque microbiota was different between HC and IBS-D patients during normal defecation.

CONCLUSIONS

Our findings suggest that colonic host-microbial interactions are altered in IBS-D patients during exacerbation of symptoms. There were no overlaps between feces and oral microbiomes.

Review article: Physical and psychological comorbidities associated with irritable bowel syndrome

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders encountered by physicians in primary and secondary care. Patients with IBS commonly present with various extraintestinal complaints, which account for a substantial clinical and economic burden. The common extraintestinal comorbidities associated with IBS include anxiety, depression, somatisation, fibromyalgia, chronic fatigue syndrome, chronic pelvic pain, interstitial cystitis, sexual dysfunction and sleep disturbance. The presence of comorbidity in IBS poses a diagnostic and therapeutic challenge with patients frequently undergoing unnecessary investigations and interventions, including surgery. This review discusses the different physical and psychological comorbidities associated with IBS, the shared pathophysiological mechanisms and potential management strategies.

Medical Therapies for Diarrhea-Predominant Irritable Bowel Syndrome

Diarrhea-predominant irritable bowel syndrome is a common functional gastrointestinal disorder that manifests with abdominal pain and diarrheal bowel patterns, without structural explanation. Diarrhea-predominant irritable bowel syndrome is a heterogeneous condition resulting from diverse pathophysiologic processes. Treatment strategies with varied mechanisms of action are beneficial in its management. The clinician must become familiar with a multi-dimensional approach to irritable bowel syndrome. The 3 approved medications are central to disease management. Effective treatment uses off-label medications and emerging therapies and a growing number of over-the-counter and supplemental agents to optimize symptom improvement for the patient with diarrhea-predominant irritable bowel syndrome.

Disruption of Circadian Rhythms and Gut Motility: An Overview of Underlying Mechanisms and Associated Pathologies

Circadian rhythms ensure that physiological processes occur at the most biologically meaningful time. The circadian timing in the gastrointestinal tract involves interlocking transcriptional and translational feedback loops that culminate in the rhythmic expression and activity of a set of clock genes and related hormones. The suprachiasmatic nucleus and peripheral core molecular clocks oscillate every 24 hours and are responsible for the periodic activity of various segments and transit along the gastrointestinal tract. Environmental cues may alter or reset these rhythms to align them with new circumstances. Colonic motility also follows a circadian rhythm with reduced nocturnal activity. Healthy humans have normal bowel motility during the day, frequently following awakening or following a meal, with minimal activity during the night. Maladjusted circadian rhythms in the bowel have been linked to digestive pathologies, including constipation and irritable bowel syndrome. Our advanced knowledge of the link between the circadian clock and gastrointestinal physiology provides potential therapeutic approaches for the treatment of gastrointestinal diseases. This review seeks to establish evidence for the correlation between circadian rhythm, bowel movements and digestive health, and examine the implications of disrupted circadian rhythms on gut physiology.

Management of functional gastrointestinal disorders

Functional gastrointestinal (GI) disorders (eg irritable bowel syndrome and functional dyspepsia) are very common conditions which are associated with very poor quality of life and high healthcare utilisation. They are caused by disorders of GI functioning, namely altered gut sensitivity, motility, microbiota, immune functioning and central nervous system processing. They cause chronic symptoms throughout the gut (eg pain, dyspepsia and altered bowel habit), all of which are made worse by maladaptive patient behaviours, stress and psychological comorbidity. Management involves a biopsychosocial approach involving changes in lifestyle and diet, addressing coexisting psychological comorbidity and using medication to treat underlying pathophysiology. Pharmacological treatment with antispasmodics, neuromodulators, motility agents and antidepressants is effective. Psychotherapy in motivated individuals is equally effective. Success of treatment is increased by a good doctor-patient relationship and so this needs to be taken into account during the consultation.

Effects of exogenous melatonin on sleep quality and menopausal symptoms in menopausal women: a systematic review and meta-analysis of randomized controlled trials

IMPORTANCE

Because of the bothersome symptoms during women's menopausal period and the severe side effects of hormone therapy, it is meaningful to find new breakthroughs in improving menopausal women's quality of life.

OBJECTIVE

We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating melatonin intake on the improvement of sleep quality, general menopausal symptom, mood states, as well as interaction of estradiol levels and body mass index (BMI) in menopausal women.

EVIDENCE REVIEW

We used the search terms "melatonin" together with "menopause" or "post-menopause" or "peri-menopause" in multiple databases online including PubMed, Web of Science, Embase, Clinical trial, Cochrane Library, and China National Knowledge Infrastructure from the first publication year to October 2020. Interesting data included characteristics of the study design, study participants, intervention, and outcome measures. Risk of biases in RCTs was evaluated with the Cochrane tool. Fixed-effect models and random-effect models were used for meta-analysis according to heterogeneity. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed in our study.

FINDINGS

Eight cohorts (n = 812) evaluating the effects of melatonin in menopausal women were included. Melatonin was used in every study with differences existing in dose (1 mg - 5 mg) and duration (3 to 12 mo). Improved physical symptoms (standard mean difference [SMD] -0.376; 95% CI, -0.599 to -0.153, P = 0.001) merged in four RCTs. Melatonin treatment resulted in no benefits to sleep quality (SMD -0.659; 95% CI, -1.535 to 0.217, P = 0.141) and general menopause symptoms (SMD -0.625; 95% CI, -1.354 to 0.105, P = 0.093) in four and three RCTs, respectively. More specifically, melatonin did not solve the psychological (SMD -0.026; 95% CI, -0.372 to 0.321, P = 0.884, I2 = 70.3%), sexual (SMD -0.661; 95% CI, -1.416 to 0.093, P = 0.086) and vasomotor (SMD -0.256; 95% CI, -0.701 to 0.188, P = 0.258) issues. No significant changes were observed in anxiety (SMD 0.018; 95% CI, -0.519 to 0.556, P = 0.946), depression (SMD 0.133; 95% CI, -0.435 to 0.702, P = 0.646), BMI (weighted mean difference 0.029 kg/m2; 95% CI, -0.183 to 0.240, P = 0.790) or estradiol levels (weighted mean difference 0.016 pg/mL; 95% CI, -1.220 to 1.252, P = 0.980).

CONCLUSIONS

Melatonin seems to improve physical symptoms in menopausal women, but the general menopausal symptoms, sleep quality, mood state, estradiol levels, and BMI did not improve under melatonin intervention. However, multiple large-scale clinical randomized trials are needed to validate our conclusions.

Biogenic amines in the colon

The gastrointestinal (GI) tract contains the highest concentration of biogenic amines in the human body. Neurons located in the GI tract, modulated by biogenic amines and various peptide and non-peptide transmitters, are called Enteric Nervous System (ENS). That explains why many medications used in neurology and psychiatry present side effects from the gut. Serotonin (5-hyroxytrypatamine, 5-HT), 95% of which is synthesized in the gut, is the most important amine (beside epinephrine and norepinephrine) colon functionality but another substances such as histamine, dopamine and melatonin are also potent in modulating intestine’s actions. Over 30 receptors for 5-HT were described in the human body, and 5-HT3, 5-HT4 and 5-HT7 are known to have the highest influence on motility and are a potent target for the drugs for treatment GI disorders, such as Irritable Bowel Syndrome (IBS) and Inflammatory Bowel Diseases (IBD). Histamine is a key biogenic amine for pathogenesis of allergy also in the colon. Alteration in histaminergic system is found in patients with diarrhea and allergic enteropathy. Dopamine affects functions of the large intestine but its modulating actions are more presented in the upper part of GI tract. Melatonin is best known for regulating circadian circle, but may also be a potent anti-inflammatory agent within the gut. Despite many years of research, it seems that more studies are needed to fully understand human colon neurochemistry.

Melatonin: From Pharmacokinetics to Clinical Use in Autism Spectrum Disorder

The role of melatonin has been extensively investigated in pathophysiological conditions, including autism spectrum disorder (ASD). Reduced melatonin secretion has been reported in ASD and led to many clinical trials using immediate-release and prolonged-release oral formulations of melatonin. However, melatonin’s effects in ASD and the choice of formulation type require further study. Therapeutic benefits of melatonin on sleep disorders in ASD were observed, notably on sleep latency and sleep quality. Importantly, melatonin may also have a role in improving autistic behavioral impairments. The objective of this article is to review factors influencing treatment response and possible side effects following melatonin administration. It appears that the effects of exposure to exogenous melatonin are dependent on age, sex, route and time of administration, formulation type, dose, and association with several substances (such as tobacco or contraceptive pills). In addition, no major melatonin-related adverse effect was described in typical development and ASD. In conclusion, melatonin represents currently a well-validated and tolerated treatment for sleep disorders in children and adolescents with ASD. A more thorough consideration of factors influencing melatonin pharmacokinetics could illuminate the best use of melatonin in this population. Future studies are required in ASD to explore further dose-effect relationships of melatonin on sleep problems and autistic behavioral impairments.

Brief Behavioral Therapy for Insomnia in Patients with Irritable Bowel Syndrome: A Pilot Study

BACKGROUND

Up to 60% of patients with irritable bowel syndrome (IBS) report fatigue and 50% meet criteria for clinical insomnia. Recent studies have demonstrated a relationship between poor sleep and next-day IBS symptoms. However, no study to-date has evaluated behavioral therapy to treat poor sleep in IBS.

AIMS

The aim of the current pilot study is to test feasibility of behavioral therapy for insomnia among patients with IBS and poor sleep.

METHODS

This randomized controlled pilot study tested the feasibility of administering brief behavioral therapy for insomnia (BBT-I) to patients with IBS who report poor sleep. Participants were randomized to BBT-I or self-monitoring control. Exploratory analyses evaluated group differences after 4 weeks of treatment.

RESULTS

A total of 25 participants were randomized to the study, 13 to BBT-I and 12 to the control group. Three participants dropped out of the treatment group. Satisfaction with treatment was high. At follow-up, there were significant differences between groups in measures of sleep quality and insomnia severity. There were trends toward significance in IBS severity score, with 40% of the BBT-I sample reporting clinically meaningful drop in symptoms compared to 17% of the control group. Similar trends were observed with belly pain and global improvement scores.

CONCLUSIONS

This pilot study demonstrates feasibility/acceptability of a brief behavioral therapy for patients with IBS and poor sleep. Additionally, this study provides preliminary evidence to suggest that treatment of sleep difficulties in patients with IBS may improve IBS symptom outcomes. Future, larger randomized controlled studies are needed.

Nociceptive responses in melatonin MT2 receptor knockout mice compared to MT1 and double MT1 /MT2 receptor knockout mice

Melatonin, a neurohormone that binds to two G protein-coupled receptors MT₁ and MT_2, is involved in pain regulation, but the distinct role of each receptor has yet to be defined. We characterized the nociceptive responses of mice with genetic inactivation of melatonin MT₁ (MT₁ ^-/- ), or MT₂ (MT₂ ^-/- ), or both MT₁ /MT₂ (MT₁ ^-/- /MT₂ ^-/- ) receptors in the hot plate test (HPT), and the formalin test (FT). In HPT and FT, MT₁ ^-/- display no differences compared to their wild-type littermates (CTL), whereas both MT₂ ^-/- and MT₁ ^-/- /MT₂ ^-/- mice showed a reduced thermal sensitivity and a decreased tonic nocifensive behavior during phase 2 of the FT in the light phase. The MT₂ partial agonist UCM924 induced an antinociceptive effect in MT₁ ^-/- but not in MT₂ ^-/- and MT₁ ^-/- /MT₂ ^-/- mice. Also, the competitive opioid antagonist naloxone had no effects in CTL, whereas it induced a decrease of nociceptive thresholds in MT₂ ^-/- mice. Our results show that the genetic inactivation of melatonin MT₂ , but not MT₁ receptors, produces a distinct effect on nociceptive threshold, suggesting that the melatonin MT₂ receptor subtype is selectively involved in the regulation of pain responses.

Sleep and pain management: a review

There is a complex interplay between sleep disturbance and patients in pain. There is an increasing appreciation of the direct effects of analgesic drugs and sleep quality. This review provides an overview of the effects of different analgesic drugs and their effects on phases of sleep. The effects of different pain conditions and their direct effects on sleep physiology are also discussed. A structured search of the scientific literature using MEDLINE and PubMed databases. Original human and animal studies were included. A multi-search term strategy was employed. An appreciation of the physiological effects of these drugs will allow a more considered prescription of them to better manage sleep disturbance.

Analgesic Efficacy of Melatonin: A Meta-Analysis of Randomized, Double-Blind, Placebo-Controlled Trials

Previous systematic reviews and meta-analyses of randomized controlled trials have reported controversial findings regarding the effects of melatonin on pain reduction. The aim of this study was to evaluate the efficacy of melatonin on pain among adults using a meta-analysis of randomized, double-blind, placebo-controlled trials (RDBPCTs). PubMed, EMBASE, the Cochrane Library, and the bibliographies of relevant articles were searched up to February 2020. Two of the authors independently evaluated eligibility of the studies based on the pre-determined criteria and extracted data. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) for the pain score change were calculated using a random-effects meta-analysis. Out of 463 that met the initial criteria, a total of 30 trials, which involved 1967 participants with 983 in an intervention group and 984 in a control group, were included in the final analysis. In a random-effects meta-analysis, the use of melatonin reduced chronic pain in all the trials (5 studies, SMD -0.65, 95% CI -0.96 to -0.34, I² = 57.2%) and high-quality trials (4 studies, SMD -0.62, 95% CI -1.01 to -0.23, I² = 49.3%). Moreover, the use of melatonin significantly reduced acute postoperative pain (11 studies, SMD -0.82, 95% CI -1.40 to -0.25, I² = 93.0%). However, the subgroup meta-analysis of high-quality RDBPCTs showed no significant association between them (6 studies, SMD -0.21, 95 % CI -0.66 to 0.24, I² = 82.4%). The current study suggests that melatonin might be used in treatment of chronic pain, while there is no sufficient evidence for acute postoperative or procedural pain. Further trials are warranted to confirm its analgesic effect.

Comparisons Between Successful Versus Unsuccessful Switches From Benzodiazepines or Zolpidem (Z-Drug) to Controlled-Release Melatonin in Patients With Major Depressive Disorder and Insomnia

OBJECTIVES

Chronic use of benzodiazepines and zolpidem (BDZ/Z-drugs) leads to dependency, cognitive impairment, and falls. Although controlled-release melatonin (Melatonin CR) may be an alternative, a switch in clinical settings has proven difficult. We investigated the factors associated with successful switch to Melatonin CR in patients with major depressive disorder (MDD) and insomnia.

METHODS

This retrospective observational study involved 170 patients diagnosed with MDD and insomnia, and aged older than 55 years, who were treated with BDZ/Z-drug for at least the past 90 days and never before exposed to Melatonin CR. All patients were treated with a standard antidepressant therapy and Melatonin CR for their insomnia. A successful switch was defined as three or more consecutive prescriptions of Melatonin CR separated by at least one-month interval, after discontinuation of the BDZ/Z-drug.

RESULTS

Seventy-nine patients (46.5%) who switched successfully showed no significant differences in sex, age, education, and occupational status compared with the unsuccessful group. The types of antidepressants used or BDZ/Z-drug treatment did not differ significantly between the two groups. Fewer somatic symptoms were observed in the successful group. In the multivariate analysis, the successful group showed significantly less somatic anxiety, shorter duration from first BDZ/Z-drug use to the first antidepressant use, and shorter total duration of BDZ/Z-drug therapy.

CONCLUSIONS

A successful switch from BDZ/Z-drug to Melatonin CR was associated with less baseline somatic anxiety, earlier use of antidepressants, and shorter total duration of BDZ/Z-drug use, but was less strongly associated with the type of antidepressants in MDD patients with insomnia.

Current and emerging pharmacological approaches for treating diarrhea-predominant irritable bowel syndrome

Introduction: Irritable bowel syndrome with diarrhea (IBS-D) is among the most common functional gastrointestinal (GI) disorders and is associated with impaired quality of life, increased health-care utilization, and significant costs to patients and society. The treatment of IBS is typically hierarchal with initial therapies consisting of dietary and lifestyle modifications. Pharmacotherapy with over-the-counter and prescription medications is also commonly used for symptomatic control in the course of therapy.Areas covered: Three medications are approved by the United States Food and Drug Administration (FDA) for IBS-D, with all of them demonstrating efficacy in randomized, placebo-controlled trials. In this review, the authors discuss the clinical trial data applicable to the current FDA approved IBS-D therapies as well as review data related to new and emerging therapies for this condition.Expert opinion: Clinicians should be familiar with emerging therapies for IBS-D as they may provide benefit to some IBS-D patients. The exact mechanisms of action of many of the emerging agents for IBS-D remain unknown. Despite substantial differences and limitations in the design and quality of supporting studies, there is an increasing body of evidence suggesting that emerging agents may promote meaningful symptom improvement in patients with IBS-D.

The use of melatonin in adult psychiatric disorders: Expert recommendations by the French institute of medical research on sleep (SFRMS)

Melatonin is a hormone secreted by the pineal gland at night. This hormone has many physiological functions, the main one being to synchronise individuals' biological rhythms. Exogenous melatonin has the same chronobiotic action, even at small doses (0.125mg). In addition, a sleep-inducing (soporific) action appears to occur in a dose-effect relationship, i.e. as the dose increases. In psychiatric disorders, these two effects could have interesting applications in clinical practice. The French institute of medical research on sleep (SFRMS) appointed a group of experts to conduct a consensus conference to study the indications of melatonin and the conditions of its prescription. An account of the conclusions on adult psychiatric disorders (presented orally at the Congress on Sleep in Marseille, 23 November 2017) is given here. Exogenous melatonin proves to be useful among patients with a stabilized psychiatric disorder or in remission, to prevent relapse in case of associated complaints of insomnia, poor quality sleep or delayed sleep phase syndrome. During acute phases, melatonin could be used as an adjuvant treatment when there are insomnia symptoms, in mood disorders (bipolar disorder, major depressive disorder, seasonal affective disorder), in attention deficit hyperactivity disorder (ADHD), in peri-surgical anxiety and in schizophrenia. In somatoform disorders, melatonin is a possible treatment for painful symptoms in fibromyalgia, irritable bowel syndrome, functional dyspeptic syndrome and temporomandibular joint dysfunction.

Tryptophan Metabolites in Irritable Bowel Syndrome: An Overnight Time-course Study

Background/Aims

Patients with irritable bowel syndrome (IBS) often report poor sleep quality. Whether poor sleep is associated with tryptophan (Trp) metabolites is unknown. We compared serum Trp metabolites in women with IBS and healthy controls (HCs) using targeted liquid chromatography mass spectrometry (LC-MS)-based profiling. In IBS only, we explored whether Trp metabolites are associated with IBS symptoms and subjective and objective sleep indices, serum cortisol, plasma adrenocorticotropic hormone (ACTH), and cortisol/ACTH levels.

Methods

Blood samples were obtained every 80 minutes in 21 HCs and 38 IBS subjects following an anticipation-of-public-speaking stressor during a sleep laboratory protocol. Subjects completed symptom diaries for 28 days. Adjacent values of metabolites were averaged to represent 4 time-periods: awake, early sleep, mid-sleep, and mid-to-late sleep. Thirteen of 20 targeted Trp metabolites were identified.

Results

Ten of 13 Trp metabolites decreased across the night, while nicotinamide increased in both groups. A MANOVA omnibus test performed after principal component analysis showed a significant difference in these 13 principal component (P = 0.014) between groups. Compared to HCs, nicotinamide levels were higher and indole-3-lactic acid levels lower in the IBS group. Melatonin and indole-3-acetic acid levels were associated with several subjective/objective sleep measures; decreased stool consistency/frequency and abdominal pain were positively associated with melatonin and serotonin in the IBS group. The kynurenine and kynurenic acid were associated with ACTH (positively) and cortisol/ACTH (negatively).

Conclusions

Nighttime Trp metabolites may provide clues to poor sleep and stress with IBS. Further study of the mechanism of metabolite action is warranted.

Does Irritable Bowel Syndrome Exist? Identifiable and Treatable Causes of Associated Symptoms Suggest It May Not

Significant shortcomings in irritable bowel syndrome (IBS) diagnosis and treatment may arise from IBS being an “umbrella” diagnosis that clusters several underlying identifiable and treatable causes for the same symptom presentation into one classification. This view is compatible with the emerging understanding that the pathophysiology of IBS is heterogeneous with varied disease mechanisms responsible for the central pathological features. Collectively, these converging views of the pathophysiology, assessment and management of IBS render the traditional diagnosis and treatment of IBS less relevant; in fact, they suggest that IBS is not a disease entity per se and posit the question “does IBS exist?” The aim of this narrative review is to explore identifiable and treatable causes of digestive symptoms, including lifestyle, environmental and nutritional factors, as well as underlying functional imbalances, that may be misinterpreted as being IBS.

Dose-Dependent Effect of Hyperbaric Oxygen Treatment on Burn-Induced Neuropathic Pain in Rats

Hyperbaric oxygen treatment (HBOT) has been used to reduce neuropathic pain. Melatonin and opioid receptors are involved in neuropathic pain, but it is not known if HBOT works through these pathways to achieve its antinociceptive effect. We divided anesthetized rats into two treatment and three sham groups. The two treatment groups received third-degree burns on their right hind paws, one treated in a hyperbaric chamber for a week and the other for two weeks. We evaluated the mechanical paw-withdrawal threshold (MWT) and expression of melatonin receptor 1 (MT1), melatonin receptor 2 (MT2), μ (MOR) and κ (KOR) opioid receptor, brain-derived neurotrophic factor (BDNF), Substance P, and calcitonin gene-related peptide (CGRP) in cuneate nucleus, dorsal horn, and hind paw skin by immunohistochemical, immunofluorescence assays and real-time quantitative polymerase chain reaction (RT-PCR). The group receiving one-week HBOT had increased expressions of MT1, MT2, MOR and KOR and decreased expressions of BDNF, Substance P, and CGRP. Their mechanically measured pain levels returned to normal within a week and lasted three weeks. This anti-allodynia effect lasted twice as long in those treated for two weeks. Our findings suggest that increasing the duration of HBOT can reduce burn-induced mechanical allodynia for an extended period of time in rats. The upregulation of melatonin and opioid receptors observed after one week of HBOT suggests they may be partly involved in attenuation of the mechanical allodynia. Downregulation of BDNF, substance P and CGRP may have also contributed to the overall beneficial effect of HBOT.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Exercise therapy of patients with irritable bowel syndrome: A systematic review of randomized controlled trials

BACKGROUND

As drug use has limitations in the treatment of irritable bowel syndrome (IBS), increasing attention is being paid to nondrug therapies and complementary treatments, especially exercise. It is known that bowel movements are more frequent and colon transit is more rapid in physically active individuals than in sedentary individuals. However, the effects of exercise on IBS are unclear.

PURPOSE

We conducted a systematic review to assess the effects of exercise on IBS.

METHODS

We searched PubMed, Web of Science, EMBASE, Cochrane Library, and two Chinese databases (Wanfang Database and Chinese Biomedical Literature [CBM]) for eligible studies. We extracted and pooled relevant information regarding the effects of exercise in patients with IBS. The primary outcomes were gastrointestinal symptoms, quality of life, depression, and anxiety.

KEY RESULTS

A total of 683 patients with IBS from 14 randomized controlled trials met our inclusion criteria. The exercise interventions in this review were yoga, walking/aerobic physical activity, Tai Ji, mountaineering, and Baduanjin qigong activity. The results of this review suggested exercise had significant benefits for patients with IBS, but studies were limited by the strong risk of bias.

CONCLUSIONS AND INFERENCES

Our findings suggest that exercise is potentially a feasible and effective treatment for IBS patients. However, because of methodologic issues, no firm conclusions could be drawn about the true effects of this intervention. Researchers should design a rigorous study to assess the effects of exercise on IBS.

The Relationship Between Daytime Salivary Melatonin and Gastrointestinal Symptoms in Young Adults Seeking Psychiatric Care

OBJECTIVE

The pathophysiology of irritable bowel syndrome (IBS) is not completely understood, although we do know that patients with IBS have a high prevalence of psychiatric comorbidity (mainly depression and anxiety disorders). Melatonin, produced in the gastrointestinal tract, influences gut motility. Psychiatric conditions are associated with circadian disturbances in peripheral melatonin levels. This study aimed to investigate associations between daytime salivary melatonin and gastrointestinal symptoms in young adult psychiatric patients.

METHODS

Ninety-six patients (86% women), aged 18-25 years (M (SD) = 21 (2)), seeking psychiatric care with primarily anxiety disorders, affective disorders, or both were included in the study. Total scores from the Gastrointestinal Symptoms Rating Scale - IBS were compared with salivary melatonin measured at three time points (30 minutes after waking up, at 11:00 hours and 30 minutes after lunch) during the waking hours of 1 day.

RESULTS

After adjustment for potential confounders, melatonin levels in saliva 30 minutes after lunch remained significantly correlated to the total Gastrointestinal Symptoms Rating Scale - IBS score after correction for multiple testing (B = 0.016, SE = 0.006, p = .015, q = 0.045). In a post hoc analysis, symptoms of gastrointestinal pain and bloating contributed most to this association.

CONCLUSIONS

In young adult psychiatric patients, salivary melatonin levels after lunch are associated with gastrointestinal symptoms, which is consistent with the proposed effect of elevated levels of gastrointestinal melatonin on gut motility. This result suggests a link between IBS symptoms and regulation of melatonin in patients with psychiatric disorders.

Melatonin and Comorbidities in Children with Autism Spectrum Disorder

PURPOSE OF REVIEW

Melatonin is used to treat sleep difficulties associated with autism spectrum disorder (ASD). There are growing evidence that melatonin could have an effect on other symptoms than sleep, such as anxiety, depression, pain, and gastrointestinal dysfunctions. Interestingly, these symptoms frequently are found as comorbid conditions in individuals with ASD. We aimed to highlight the potential effect of melatonin on these symptoms.

RECENT FINDINGS

Animal and human studies show that melatonin reduces anxiety. Regarding the effect of melatonin on pain, animal studies are promising, but results remain heterogeneous in humans. Both animal and human studies have found that melatonin can have a positive effect on gastrointestinal dysfunction.

SUMMARY

Melatonin has the potential to act on a wide variety of symptoms associated with ASD. However, other than sleep difficulties, no studies exist on melatonin as a treatment for ASD comorbid conditions. Such investigations should be on the research agenda because melatonin could improve a multitude of ASD comorbidities and, consequently, improve well-being.

The role of melatonin and cortisol circadian rhythms in the pathogenesis of infantile colic

BACKGROUND

Despite the high prevalence of infantile colic, the pathogenesis remains incompletely understood. Cortisol and melatonin hormones affect gastrointestinal system development in several ways, and interestingly, both cortisol and melatonin's circadian rhythms begin around the 3rd month in which infantile colic symptoms start to decrease. We hypothesized that infantile colic might associate with desynchronization of normal circadian rhythms of these hormones. In this study, we aimed to investigate the role of melatonin and cortisol in the pathogenesis of infantile colic.

METHODS

Patients who were diagnosed as infantile colic according to Wessel's "rule of three" were enrolled in the colic group. We measured the saliva melatonin and cortisol levels of colic group and control group infants. In both groups, the saliva samples were taken in mornings and at evenings, at the time of diagnosis and 6th month.

RESULTS

Fifty-five infants finished the study. Melatonin circadian rhythm developed earlier in the control group than the infantile colic group in our study. We found no significant difference between the daily mean cortisol levels. However, infants with colic had flatter daily cortisol slope than controls which pointed out the probability that they had a less clearly defined cortisol rhythm than infants without colic.

CONCLUSIONS

We found an association between melatonin levels and infantile colic. However, more research is needed to fully understand the role of hypothalamic-pituitary-adrenal axis and hormone's role on infantile colic physiopathology.

Agomelatine, a novel therapeutic option for the management of irritable bowel syndrome

WHAT IS KNOWN AND OBJECTIVE

Irritable bowel syndrome (IBS) is a complex and chronic, relapsing gastrointestinal condition that affects more than 10% of the population worldwide. There is a pressing need for new therapeutic strategies in the management of IBS. Increasing research has shed light on the modulatory functions of melatonin on pain, local inflammation and motility in the gastrointestinal tract. However, melatonin's effects are limited by its extensive first-pass metabolism and short half-life.

COMMENT

Agomelatine, a naphthalene analog of melatonin, is a novel melatonergic drug with a longer half-life and a comparatively greater affinity for MT1 and MT2 melatonin receptors than melatonin itself. Agomelatine also shows serotonin 5-HT3 receptor antagonist activity, which is theoretically of benefit for patients with IBS with diarrhoea (IBS-D) as it regulates gastrointestinal motility and visceral sensory mechanisms. Although only one clinical study of agomelatine use in patients with IBS exists, we believe that agomelatine is a safe and efficacious multimodal agent with untapped potential in the management of IBS.

WHAT IS NEW AND CONCLUSION

Numerous comorbidities are associated with IBS, including chronic pain syndromes and psychiatric disorders. Coupled with its antidepressant actions, agomelatine could serve as an effective adjunct therapeutic. Agomelatine should be considered in our therapeutic armamentarium for IBS management.

Functional abdominal pain disorders in children

Chronic abdominal pain is a common problem in pediatric practice. The majority of cases fulfill the Rome IV criteria for functional abdominal pain disorders (FAPDs). At times, these disorders may lead to rather serious repercussions. Area covered: We have attempted to cover current knowledge on epidemiology, pathophysiology, risk factors related to pathophysiology, clinical evaluation and management of children with FAPDs. Expert commentary: FAPDs are a worldwide problem with a pooled prevalence of 13.5%. There are a number of predisposing factors and pathophysiological mechanisms including stressful events, child maltreatment, visceral hypersensitivity, altered gastrointestinal motility and change in intestinal microbiota. It is possible that the environmental risk factors intricately interact with genes through epigenetic mechanisms to contribute to the pathophysiology. The diagnosis mainly depends on clinical evaluation. Commonly used pharmacological interventions do not play a major role in relieving symptoms. Centrally directed, nonpharmacological interventions such as hypnotherapy and cognitive behavioral therapy have shown both short and long term efficacy in relieving pain in children with FAPDs. However, these interventions are time consuming and need specially trained staff and therefore, not currently available at grass root level. Clinicians and researchers should join hands in searching for more pragmatic and effective therapeutic modalities to improve overall care of children with FAPDs.

Wake-up Call to Clinicians: The Impact of Sleep Dysfunction on Gastrointestinal Health and Disease

Sleep dysfunction is an epidemic affecting a large portion of the adult population. Recent studies have linked sleep dysfunction with an upregulation of proinflammatory cytokines (eg, tumor necrosis factor-α, interleukin-1 and interleukin-6), the implications of which can have a profound impact on a variety of gastrointestinal disease. In particular, sleep dysfunction seems to accelerate disease states characterized by inflammation (eg, gastroesophageal reflux disease, irritable bowel syndrome and functional dyspepsia, chronic liver disease, inflammatory bowel disease, and colorectal cancer). This article evaluates the complex interplay between sleep dysfunction and gastrointestinal health and disease.