Melatonin improves bowel symptoms in female patients with irritable bowel syndrome: a double-blind placebo-controlled study

Efficacy of melatonin for treatment and prevention of neonatal necrotizing enterocolitis: a systematic review

The purpose of this study was to systematically review the available literature evaluating the use of melatonin for preventing and treating neonatal necrotizing enterocolitis (NEC). A systematic review of studies examining the effect of melatonin on neonatal NEC was conducted. The databases of Medline, Scopus, WOS, Embase, and Cochrane Central Register of Controlled Trials were searched for relevant studies. For risk of bias and applicability, The ROB2 tool was used for randomized controlled trials, and the ROBINS-I tool was used for non-randomized controlled trials. Three studies, comprising 106 preterm neonates, were included in the review, whose mean gestational ages ranged from 31.8 to 33.53 weeks. Melatonin doses varied among the studies. A randomized, double-blind, placebo-controlled study revealed that early administration of melatonin in preterm newborns resulted in a decrease in lipid peroxidation during the initial days of life. Two studies evaluated the role of melatonin in NEC. Both reported significant clinical and laboratory improvements in the melatonin groups, including reduced abdominal distension, metabolic acidosis, thrombocytopenia, hyponatremia, and lower mortality rates compared to control groups. This systematic review suggests that melatonin may be a potential therapeutic approach for NEC in preterm infants. However, further RCTS are needed to establish its therapeutic or preventive role.

Novel hypothesis and therapeutic interventions for irritable bowel syndrome: interplay between metal dyshomeostasis, gastrointestinal dysfunction, and neuropsychiatric symptoms

Irritable bowel syndrome is a gastrointestinal disorder due to multiple pathologies. While patients with this condition experience anxiety and depressed mood more frequently than healthy individuals, it is unclear how gastrointestinal dysfunction interacts with such neuropsychiatric symptoms. Data suggest that irritable bowel syndrome patients predominantly display a lower zinc intake, which presumably impairs enterochromaffin cells producing 5-hydroxytryptamine, gut bacteria fermenting short-chain fatty acids, and barrier system in the intestine, with the accompanying constipation, diarrhea, low-grade mucosal inflammation, and visceral pain. Dyshomeostasis of copper and zinc concentrations as well as elevated pro-inflammatory cytokine levels in the blood can disrupt blood-cerebrospinal fluid barrier function, leading to locus coeruleus neuroinflammation and hyperactivation with resultant amygdalar overactivation and dorsolateral prefrontal cortex hypoactivation as found in neuropsychiatric disorders. The dysregulation between the dorsolateral prefrontal cortex and amygdala is likely responsible for visceral pain-related anxiety, depressed mood caused by anticipatory anxiety, and visceral pain catastrophizing due to catastrophic thinking or cognitive distortion. Collectively, these events can result in a spiral of gastrointestinal symptoms and neuropsychiatric signs, prompting the progression of irritable bowel syndrome. Given that the negative feedback mechanism in regulation of the hypothalamic-pituitary-adrenal axis is preserved in a subset of neuropsychiatric cases, dorsolateral prefrontal cortex abnormality accompanied by neuropsychiatric symptoms may be a more significant contributing factor in brain-gut axis malfunction than activation of the hypothalamic corticotropin-releasing hormone system. The proposed mechanistic model could predict novel therapeutic interventions for comorbid irritable bowel syndrome and neuropsychiatric disorders.

Placebo response variability on health-related quality of life outcomes in irritable bowel syndrome: an arm-based network meta-analysis

OBJECTIVES

The impact of placebo response on health outcomes in various diseases, including IBS, is significant. To better understand the effect of different placebo administration methods on the observed outcomes in IBS studies, this meta-analysis aims to explore research findings on the degree of improvement.

METHODS

The meta-analysis included 45 randomized, double-blind, placebo-controlled clinical trials involving 5174 patients with confirmed IBS (excluding those with significant comorbidities). The trials were designed to compare the efficacy of different placebo interventions. The primary outcome was the Irritable Bowel Syndrome Severity Scoring System (IBS-SSS), and secondary outcomes included the Irritable Bowel Syndrome Quality of Life Instrument (IBS-QoL) and the IBS Symptom Visual Analog Scale (VAS). An arm-based Bayesian network meta-analysis was performed to examine the relative effectiveness of the placebo interventions on the outcomes.

RESULTS

The analysis revealed that sham moxibustion exhibited the most significant efficacy in reducing IBS-SSS (MD -260.00, 95% CrIs: -288.00 to -232.00). Additionally, sham FMT resulted in significant improvements in IBS-QOL scores (MD 9.23, 95% CrIs - 3.69 to 22.30). Meanwhile, placebo tablet interventions were found to be the most effective in reducing VAS scores (MD 4.71, 95% CrIs, -1.14 to 11.10). Overall, this synthesis provides detailed insights into the effectiveness of placebos in addressing different outcome measures.

CONCLUSIONS

Sham moxibustion appears to provide subjective benefits for patients' IBS symptoms. However, the evidence for its efficacy is less robust compared to other interventions, as assessed by GRADE. Understanding the placebo effect in IBS management is crucial for clinical practice and drug development, particularly in placebo comparisons.

REGISTRATION ID

INPLASY2024110111. https://doi.org/10.37766/inplasy2024.11.0111 .

Effect of improving sleep quality the night before surgery with zolpidem on postoperative gastrointestinal function in patients undergoing laparoscopic partial colorectal resection: a randomized, double-blind, controlled trial

BACKGROUND

Sleep is one of the basic physiological needs of human beings. Preoperative sleep disorders are associated with poor prognosis in surgical patients, and sleep disorders have been shown to be one of the risk factors for gastrointestinal dysfunction. However, there are now few studies to investigate whether improving preoperative sleep disorders can promote the recovery of postoperative gastrointestinal function. This study aimed to investigate the effects and significance of improving preoperative sleep quality with zolpidem on postoperative gastrointestinal function.

METHODS

In this prospective, randomized, double-blind clinical trial, 76 patients undergoing elective laparoscopic partial colorectal resection and with a Pittsburgh Sleep Quality Index (PSQI) score > 5, were randomly divided into two groups. The zolpidem group (Group Z, n = 38) was given a capsule containing 10 mg of zolpidem the night before the operation, and the control group (Group C, n = 38) was given an empty capsule the night before the operation. Follow-up visits were performed on the 1st, 3rd, and 7th postoperative days, respectively. The primary outcome of this study was the I-FEED (Intake, Feeling nauseated, Emesis, Physical Exam, and Duration of symptoms) score on the third postoperative day (POD3). Secondary outcomes included time to postoperative first flatus, first feces, and first food intake (semi-liquid diet), I-FEED scores, visual analog scores (VAS) during coughing and at rest, times of patient-controlled intravenous analgesia (PCIA) effective presses, sufentanil dosage, number of remedial analgesia in the 24-hour postoperative period, and changes in inflammatory markers (TNF-α).

RESULTS

Compared with Group C, Group Z had a lower I-FEED score on POD1 (P < 0.05) and shorter time to first flatus and first food intake (P < 0.05); there were significant differences between the two groups in VAS scores during coughing and at rest on POD1, VAS score during coughing on POD3, times of PCIA effective presses and sufentanil dosage in the 24-hour postoperative period, and patient satisfaction (P < 0.05).

CONCLUSION

For patients with sleep disorders, the use of zolpidem to improve sleep the night before surgery is beneficial in partially improving postoperative gastrointestinal function, relieving postoperative pain, and increasing patient satisfaction.

TEST REGISTRATION

ChiCTR2300077566 November 13, 2023.

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.

Differentially expressed genes of esophageal tissue in male acute and chronic sleep deprivation mice

Gastroesophageal reflux disease (GERD) is associated with sleep disturbances. However, mechanisms underlying these interactions remain unclear. Male acute and chronic sleep deprivation (SD) mice were used for this study. Mice in the chronic SD group exhibited anxiety- and depression-like behaviors. We further performed high-throughput genome sequencing and bioinformatics analysis to screen for featured differentially expressed genes (DEGs) in the esophageal tissue. The acute SD group, comprised 25 DEGs including 14 downregulated and 11 upregulated genes. Compared with the acute SD group, more DEGs were present in the chronic SD group, with a total of 169 DEGs, including 88 downregulated and 81 upregulated genes. Some DEGs that were closely related to GERD and associated esophageal diseases were significantly different in the chronic SD group. Quantitative real-time polymerase chain reaction verified the downregulation of Krt4, Krt13, Krt15 and Calml3 and upregulation of Baxl1 and Per3. Notably, these DEGs are involved in biological processes, which might be the pathways of the neuroregulatory mechanisms of DEGs expression.

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.

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.

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.

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.

Nocebo response intensity and influencing factors in the randomized clinical trials of irritable bowel syndrome: A systematic review and meta-analysis

OBJECTIVE

To estimate the magnitude of the nocebo response and explore its influencing factors in irritable bowel syndrome (IBS).

METHODS

The PubMed, Embase, and Cochrane Library databases were searched up to March 2021. We performed a random effects meta-analysis of the proportion of adverse events (AEs) in placebo-treated patients with IBS who are involved in parallel-designed, randomized, placebo-controlled trials investigating pharmacological interventions and evaluated the effect of trial characteristics on the magnitude of the nocebo response rate.

RESULTS

A total of 6,107 studies were identified from the databases. After evaluation, 53 met the eligibility criteria and were included. The overall pooled nocebo response rate was 32% (95% CI: 26-38%). The most commonly reported AEs were headache (9%), nasopharyngitis (7%), abdominal pain (4%), and nausea (4%). The nocebo response rate was low compared with that in the treatment group applying probiotics, antispasmodics, and Traditional Chinese medicine, but high compared with that in antibiotic treatment group. The nocebo rate in patients using diaries to record AEs was lower than the average, and was higher in patients recording through checkup.

DISCUSSION

Patients with IBS have significant nocebo response intensity in clinical trials. Based on findings in this study, we recommend the researchers pay attention to the common AEs and carefully analyze the relation to the intervention.

Melatonin as an Antimicrobial Adjuvant and Anti-Inflammatory for the Management of Recurrent Clostridioides difficile Infection

Background:Clostridioides difficile (C. difficile) infection (CDI) is strongly associated with inflammation and has the potential to cause recurrent infections. Pre-clinical data suggest that melatonin has beneficial effects in the gastrointestinal tract due to its anti-inflammatory and antibacterial properties. This analysis examines the association between melatonin and the risk of recurrent CDI. Methods: A retrospective cohort study was conducted among patients with an inpatient diagnosis of CDI along with a positive C. difficile polymerase chain reaction (PCR) or enzyme immunoassay (EIA) test result. Patients were followed until the first study end point (death) or the first instance of recurrent infection. Propensity-score weighting was utilized accounting for confounding factors and weighted Cox models were estimated. Results: A total of 24,782 patients met the inclusion criteria, consisting of 3457 patients exposed to melatonin and 21,325 patients with no melatonin exposure. The results demonstrate that those exposed to melatonin were associated with a 21.6% lower risk of recurrent CDI compared to patients without melatonin exposure (HR = 0.784; 95% CI = 0.674-0.912). Conclusion: Our results demonstrate a decreased rate of recurrent CDI in patients exposed to melatonin. Further research on melatonin as an antimicrobial adjuvant and anti-inflammatory is warranted for the management of recurrent CDI.

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.

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.

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.

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.

Adjuvant use of melatonin for pain management in dysmenorrhea - a randomized double-blinded, placebo-controlled trial

Purpose

Dysmenorrhea is a common, recurring, painful condition with a global prevalence of 71%. The treatment regime for dysmenorrhea includes hormonal therapies and NSAID, both of which are associated with side effects.

A dose of 10 mg melatonin daily has previously been shown to reduce the level of pelvic pain in women with endometriosis. We chose to investigate how this regime, administered during the week of menstruation, would affect women with dysmenorrhea but without any signs of endometriosis, as adjuvant analgesic treatment.

Methods

Forty participants with severe dysmenorrhea were randomized to either melatonin or placebo, 20 in each group. Our primary outcome was pain measured with numeric rating scale (NRS); a difference of at least 1.3 units between the groups was considered clinically significant. Secondary outcomes were use of analgesics, as well as absenteeism and amount of bleeding. Mixed model was used for statistical analysis.

Results

Eighteen participants completed the study in the placebo group and 19 in the melatonin group. Mean NRS in the placebo group was 2.45 and 3.18 in the melatonin group, which proved to be statistically, although not clinically significant.

Conclusion

This randomized, double-blinded, placebo-controlled trial could not show that 10 mg of melatonin given orally at bedtime during the menstrual week had better analgesic effect on dysmenorrhea as compared with placebo. However, no adverse effects were observed.

Clinical trials

NCT03782740 registered on 17 December 2018.

Irritable bowel syndrome and migraine: evidence from Mendelian randomization analysis in the UK Biobank

BACKGROUND

Irritable Bowel Syndrome (IBS) and Migraine are two diseases featuring high prevalence. Previous studies have suggested a relationship between IBS and migraine, although the causal association remains unclear. The authors sought to explore the causal association between IBS and migraine, and to show the importance of migraine prevention in IBS patients.

METHODS

This study conducted a Mendelian randomization analysis to explore the association of IBS with migraine. Genetic association with migraine was acquired from the UK Biobank (UKB) genetic databases (cases: 1,072; controls: 360,122). The authors performed estimation using Inverse Variance Weighting (IVW), along with Maximum Likelihood, MR-RAPS, MR-Egger, and Weighted Median for sensitivity analysis. Considering possible bias, they also conducted polymorphism, heterogeneity, and directional analysis.

RESULTS

The IVW estimation genetically predicted the causal association between IBS and migraine (OR = 1.09, 95% CI 1.01 to 1.17, p = 0.03). Neither statistical horizontal pleiotropy (MR Egger p = 0.42; MR-PRESSO p = 0.78) nor possible heterogeneity (IVW Q = 26.15, p = 0.80) was found. Reverse causation was also not detected (p steiger<0.01).

CONCLUSION

Mendelian randomization analysis supported a potential causal association between IBS and migraine, providing enlightenment for disease prevention and control.

Relative risk of functional dyspepsia in patients with sleep disturbance: a population-based cohort study

Increased prevalence of sleep disorders has been found in patients with functional dyspepsia; however, direction of causality remains unclear. Our aim was to compare the risk of incident functional dyspepsia between patients with and without sleep disturbance from a large population-based sample. Utilizing a nation-wide health insurance administrative dataset, we assembled an 11-year historic cohort study to compare subsequent incidence of diagnosed functional dyspepsia between adult patients with any diagnosis of sleep disturbance and age- and gender-matched controls. Hazard ratios adjusted for other relevant comorbidities and medications were calculated using Cox regression models. 45,310 patients with sleep disorder and 90,620 controls were compared. Patients with sleep apnea had a 3.3-fold (95% confidence interval: 2.82 ~ 3.89) increased hazard of functional dyspepsia compared with controls. This increased risk persisted regardless of previously diagnosed depression coexisted. Sleep disturbance was associated with an increased risk of subsequent functional dyspepsia. Potential mechanisms are discussed.

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.

Complementary and Alternative Medicine Therapies for Irritable Bowel Syndrome

Complementary and alternative medicine (CAM) is a term used to define a broad range of therapies, most commonly grouped into natural products, mind-body medicine, and traditional systems of medicine. Patients with irritable bowel syndrome (IBS) commonly use CAM therapies, although there are many barriers that may keep patients and providers from talking about a patient's CAM use. Despite limited quantity and quality of evidence of CAM for IBS, providers can better counsel patients on CAM use by understanding pitfalls related to CAM use and by learning what is known about CAM.

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.

Role of a berberine-based nutritional supplement in reducing diarrhea in subjects with functional gastrointestinal disorders

BACKGROUND

Berberine, an alkaloid obtained by extraction from Berberis spp., is a botanical that is widely used in the nutraceutical sector to control cholesterol and blood glucose levels. It is also a molecule that is effective in limiting diarrhea due to its multi-factorial properties, including its antimicrobial, gut eubiotic and antisecretive actions, and its ability to slow gut motility. In our routine clinical practice, we have suggested the use of a berberine-based nutraceutical, formulated with melatonin and depolymerized guar gum, to patients affected by functional diarrhea (FD) or by diarrhea-type irritable bowel syndrome (IBS-D).

METHODS

We have therefore retrospectively analyzed the clinical effect of such a nutritional supplement in these two sub-groups of patients.

RESULTS

Despite the highly pragmatic scheme of our study, our findings strongly confirm the antidiarrheal properties of berberine and recommend its use in some gut functional diseases characterized by frequent evacuation of mushy and/or watery stools. In fact, even after 30 days of treatment, the berberine-based nutritional supplement significantly reduces diarrheal events by 50-70%. After 90 days, this reduction improves to between 70 and 80%, with a reduction of more than 60% in the number of evacuations per week and with more than 50% of treated subjects demonstrating normalized, according to self-reported Bristol Stool Scale categorization, stool consistency. The product is well tolerated and adherence to the proposed therapy is good. Common side effects of the product are flatulence and meteorism, likely due to the "acarbose-like" berberine effects on gut α-glucosidase.

CONCLUSIONS

Patients, especially those preferring "natural" therapy, can be successfully treated, when affected by a gut functional disease characterized by diarrhea, by berberine-based products.

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.

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.

Glucocorticoid receptors involved in melatonin inhibiting cell apoptosis and NLRP3 inflammasome activation caused by bacterial toxin pyocyanin in colon

The immunoinhibitory effect of glucocorticoid and immunoenhancing attributes of melatonin (MEL) are well known, however, the involvement of glucocorticoid receptor (GR) in melatonin modulation of bacterial toxins caused-inflammation has not been studied in colon. Pyocyanin (PCN), a toxin released by Pseudomonas aeruginosa, can destroy cells through generating superoxide products and inflammatory response. Here we report that PCN treatment elevated the generation of reactive oxygen species (ROS), which further lead to mitochondrial swelling and caspase cascades activation both in vivo and in vitro. However, MEL treatment alleviated the oxidative stress caused by PCN on cells through scavenging ROS and restoring the expression of antioxidant enzyme so that to effectively alleviate the apoptosis. Large amounts of ROS can activate the NLRP3 signaling pathway, so MEL inhibited PCN induced NLRP3 inflammasome activation and inflammatory cytokines (IL-1β, IL-8, and TNF-α) secretion. In order to further investigate the molecular mechanism, goblet cells were exposed to MEL and PCN in the presence of luzindole and RU486, inhibitors of MEL receptors and GR respectively. It was found that PCN significantly inhibited the expression level of GR, and MEL effectively alleviated the inhibition phenomenon. Moreover, we found that MEL mainly upregulated the expression of GR to achieve its anti-inflammatory and anti-apoptotic functions rather than through its own receptor (MT2) in colon goblet cells. Therefore, MEL can reverse the inhibitory effects of PCN on GR/p-GR expression to present its anti-oxidative and anti-apoptotic function.

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.

Melatonin and morphine: potential beneficial effects of co-use

Morphine is a potent analgesic agent used to control acute or chronic pain. Chronic administration of morphine results in analgesic tolerance, hyperalgesia, and other side effects including dependence, addiction, respiratory depression, and constipation, which limit its clinical usage. Therefore, identifying the new analgesics with fewer side effects which could increase the effect of morphine and reduce its side effects is crucial. Melatonin, a multifunctional molecule produced in the body, is known to play an important role in pain regulation. The strong anti-inflammatory effect of melatonin is suggested to be involved in the attenuation of the pain associated with inflammation. Melatonin also increases the anti-nociceptive actions of opioids, such as morphine, and reverses their tolerance through regulating several cellular signaling pathways. In this review, published articles evaluating the effect of the co-consumption of melatonin and morphine in different conditions were investigated. Our results show that melatonin has pain-killing properties when administered alone or in combination with other anti-nociceptive drugs. Melatonin decreases morphine consumption in different pathologies. Furthermore, attenuation of morphine intake can be accompanied by reduction of morphine-associated side-effects, including physical dependence, morphine tolerance, and morphine-related hyperalgesia. Therefore, it is reasonable to believe that the combination of melatonin with morphine could reduce morphine-induced tolerance and hyperalgesia, which may result from anti-inflammatory and antioxidant properties of melatonin. Overall, we underscore that, to further ameliorate patients' life quality and control their pain in various pathological conditions, melatonin deserves to be used with morphine by anesthesiologists in clinical practice.

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.

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.

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.

Genetic and biochemical changes of the serotonergic system in migraine pathobiology

Migraine is a brain disorder characterized by a piercing headache which affects one side of the head, located mainly at the temples and in the area around the eye. Migraine imparts substantial suffering to the family in addition to the sufferer, particularly as it affects three times more women than men and is most prevalent between the ages of 25 and 45, the years of child rearing. Migraine typically occurs in individuals with a genetic predisposition and is aggravated by specific environmental triggers. Attempts to study the biochemistry of migraine began as early as the 1960s and were primarily directed at serotonin metabolism after an increase of 5-hydroxyindoleacetic acid (5-HIAA), the main metabolite of serotonin was observed in urine of migraineurs. Genetic and biochemical studies have primarily focused on the neurotransmitter serotonin, considering receptor binding, transport and synthesis of serotonin and have investigated serotonergic mediators including enzymes, receptors as well as intermediary metabolites. These studies have been mainly assayed in blood, CSF and urine as the most accessible fluids. More recently PET imaging technology integrated with a metabolomics and a systems biology platform are being applied to study serotonergic biology. The general trend observed is that migraine patients have alterations of neurotransmitter metabolism detected in biological fluids with different biochemistry from controls, however the interpretation of the biological significance of these peripheral changes is unresolved. In this review we present the biology of the serotonergic system and metabolic routes for serotonin and discuss results of biochemical studies with regard to alterations in serotonin in brain, cerebrospinal fluid, saliva, platelets, plasma and urine of migraine patients.

[Antioxidant, anti-inflammatory and sedative effects of melatonin: results of clinical trials]

A literature review of clinical trials and systematic reviews on the antioxidant and anti-inflammatory effects of melatonin is presented. The results of animal studies and recent publications on the effects of melatonin in humans are summarized. Melatonin protects the cardiovascular system from destructive effects of ischemia/reperfusion, when the drug has been timely administered, has a neuroprotective effect in newborns with asphyxia. It is an effective drug in complex treatment of irritable bowel syndrome and inflammatory bowel diseases (Crohn's disease and ulcerative colitis). As an alternative to benzodiazepines, melatonin can be used for premedication and anxiety reduction in surgical interventions.

Daily NO rhythms in peripheral clocks in aging male Wistar rats: protective effects of exogenous melatonin

In mammals suprachiasmatic nucleus (SCN), acts as a light entrainable master clock and by generation of temporal oscillations regulates the peripheral organs acting as autonomous clocks resulting in overt behavioral and physiological rhythms. SCN also controls synthesis and release of melatonin (hormonal message for darkness) from pineal. Nitric Oxide (NO) acts as an important neurotransmitter in generating the phase shifts of circadian rhythms and participates in sleep-wake processes, maintenance of vascular tone as well as signalling and regulating inflammatory processes. Aging is associated with disruption of circadian timing system and decline in endogenous melatonin leading to several physiological disorders. Here we report the effect of aging on NO daily rhythms in various peripheral clocks such as kidney, intestine, liver, heart, lungs and testis. NO levels were measured at zeitgeber time (ZT) 0, 6, 12 and 18 in these tissues using Griess assay in male Wistar rats. Aging resulted in alteration of NO levels as well as phase of NO in both 12 and 24 months groups. Correlation analysis demonstrated loss of stoichiometric interaction between the various peripheral clocks with aging. Age induced alterations in NO daily rhythms were found to be most significant in liver and, interestingly least in lungs. Neurohormone melatonin, an endogenous synchroniser and an antiaging agent decreases with aging. We report further differential restoration with exogenous melatonin administration of age induced alterations in NO daily rhythms and mean levels in kidney, intestine and liver and the stoichiometric interactions between the various peripheral clocks.

Pain control by melatonin: Physiological and pharmacological effects

Pain and anxiety are the most common neurological responses to many harmful or noxious stimuli and their management clinically is often challenging. Many of the frequently used morphine-based drugs, non-steroid anti-inflammatory drugs and acetaminophen, while efficient for treating pain, lead to patients suffering from several unwanted side effects. Melatonin, produced from the pineal body is a hormone of darkness, is involved in the control of circadian rhythms, and exerts a number of pharmacological effects. Melatonin mediates its actions through MT1/MT2 melatonin receptors on the cell membrane and also through RZR/ROR nuclear orphan receptors. Chronic pain syndromes are often associated with the desynchronization of circadian and biological rhythms, which also cause disturbances in the sleep-wake cycle. Melatonin-mediated analgesic effects seem to involve β-endorphins, GABA receptor, opioid receptors and the nitric oxide-arginine pathway. The effectiveness of melatonin as an analgesic and anxiolytic agent has been demonstrated in various animal models of pain and this led to the use of melatonin clinically in different pathological conditions and also in patients undergoing surgery. Melatonin was found to be effective in many of these cases as an anxiolytic and analgesic agent, indicating its clinical application.

Effects of disturbed sleep on gastrointestinal and somatic pain symptoms in irritable bowel syndrome

BACKGROUND

Sleep disturbances are common, and perhaps are even more prevalent in irritable bowel syndrome (IBS).

AIMS

To determine the effect of measured sleep on IBS symptoms the following day, IBS-specific quality of life (IBS-QOL) and non-GI pain symptoms.

METHODS

IBS patients' sleep patterns were compared to healthy individuals via wrist-mounted actigraphy over 7 days. Daily bowel pain logs (severity, distress; 10-point Likert) stool pattern (Bristol scale) and supporting symptoms (e.g. bloating, urgency; 5-point Likert) were kept. Validated measures, including the GI Symptom Rating Scale-IBS, Visceral Sensitivity Index, Pittsburgh Sleep Quality Index and the IBS-Quality of Life were collected. Mediation analysis explored the relationship between sleep, mood and bowel symptoms.

RESULTS

Fifty subjects (38.6 ± 1.0 years old, 44 female; 24 IBS and 26 healthy controls) completed sleep monitoring. IBS patients slept more hours per day (7.7 ± 0.2 vs. 7.1 ± 0.1, P = 0.008), but felt less well-rested. IBS patients demonstrated more waking episodes during sleep (waking episodes; 12.1 vs. 9.3, P < 0.001). Waking episodes predicted worse abdominal pain (P ≤ 0.01) and GI distress (P < 0.001), but not bowel pattern or accessory IBS symptoms (P > 0.3 for each). Waking episodes negatively correlated with general- and IBS-specific QOL in IBS (r = -0.58 and -0.52, P < 0.001 for each). Disturbed sleep effects on abdominal pain were partially explained by mood as an intermediate.

CONCLUSIONS

Sleep disturbances are more common in irritable bowel syndrome, and correlate with IBS-related pain, distress and poorer irritable bowel syndrome-related quality of life. Disturbed sleep effects extend beyond the bowel, leading to worse mood and greater somatic pain in patients with the irritable bowel syndrome.

Melatonin in Chronic Pain Syndromes

Melatonin is a neurohormone secreted by epiphysis and extrapineal structures. It performs several functions including chronobiotic, antioxidant, oncostatic, immune modulating, normothermal, and anxiolytic functions. Melatonin affects the cardiovascular system and gastrointestinal tract, participates in reproduction and metabolism, and body mass regulation. Moreover, recent studies have demonstrated melatonin efficacy in relation to pain syndromes. The present paper reviews the studies on melatonin use in fibromyalgia, headaches, irritable bowel syndrome, chronic back pain, and rheumatoid arthritis. The paper discusses the possible mechanisms of melatonin analgesic properties. On one hand, circadian rhythms normalization results in sleep improvement, which is inevitably disordered in chronic pain syndromes, and activation of melatonin adaptive capabilities. On the other hand, there is evidence of melatonin-independent analgesic effect involving melatonin receptors and several neurotransmitter systems.

Role of environmental pollution in irritable bowel syndrome

Irritable bowel syndrome (IBS), with the prevalence of 10%-20 % of the population has become an emerging problem worldwide. IBS is a functional gastrointestinal (GI) disorder characterized by abdominal pain or discomfort and altered bowel habits. The etiology of IBS contains genetic, psychological, and immunological factors, and has not been fully elucidated; of note, recent studies also point at environmental pollution and its role in the development of functional GI diseases. In this review we focus on several environmental factors, such as bacterial contamination, air pollution, radiation and even stress as potential triggers of IBS. We discuss associated disturbances in homeostasis, such as changes in intestinal microbiome and related pathophysiological mechanisms. Based on the effect of environmental factors on the GI tract, we also propose novel targets in IBS treatment.

[Melatonin in chronic pain syndromes]

Melatonin, a neurohormone synthesized by the epiphysis and extrapineal structures, has several functions including chronobiotic, antioxidant, oncostatic, immunomodulating, normothymic and anxiolytic ones. It impacts on the cardiovascular system and the gastrointestinal tract and is involved in reproductive functions, metabolism and body mass regulation. Moreover, recent studies have demonstrated the efficacy of melatonin in pain syndromes. The authors present a literature review on the studies of melatonin in treatment of fibromyalgia, headache, irritated bowel syndrome, chronic back pain and rheumatoid arthritis. Possible mechanisms of analgesic properties of melatonin are discussed. On one hand, there is the improvement of sleep and activation of own adaptive potential of melatonin by normalizing circadian rhythms inevitably disturbed in chronic pain syndromes. On the other hand, there are the data on the analgesic effect of melatonin realized through melatonin receptors and several neurotransmitter systems.

Melatonin regulation as a possible mechanism for probiotic (VSL#3) in irritable bowel syndrome: a randomized double-blinded placebo study

BACKGROUND

Probiotics have treatment efficacy in irritable bowel syndrome (IBS), but the exact mechanism remains obscure. One hypothesis is the mediation of melatonin levels, leading to changes in IBS symptoms.

AIM

The purpose of this study was to evaluate the effects of a probiotic, VSL#3, on symptoms, psychological and sleep parameters, and pain sensitivity in IBS, and relate these parameters to in vivo melatonin levels.

METHODS

Forty-two IBS patients were randomly assigned to receive VSL#3 or placebo for 6 weeks. Subjects completed bowel and psychological questionnaires, underwent rectal sensitivity testing and saliva melatonin assays.

RESULTS

Abdominal pain duration and distension intensity decreased significantly in the probiotic group, along with an increase in rectal distension pain thresholds. A correlation between increase in pain tolerance and improvement in abdominal pain scores (r = 0.51, p = 0.02) was seen with probiotic. There was an increase in salivary morning melatonin levels in males treated with VSL#3, which correlated (r = 0.61) with improved satisfaction in bowel habits. When grouped based on baseline diurnal melatonin levels, patients with normal diurnal fluctuations showed an increase in morning melatonin levels with VSL#3 treatment, which significantly correlated with improved satisfaction in bowel habits (r = 0.68). They also had reduced symptom severity scores and abdominal pain duration when treated with VSL#3, as well as satisfaction with bowel movements and quality-of-life.

CONCLUSIONS

VSL#3 improved symptoms and increased rectal pain thresholds. Symptom improvement correlated with a rise in morning melatonin, significant in males and subjects with normal circadian rhythm. This suggests that probiotics may act by influencing melatonin production, hence modulating IBS symptoms, in individuals with a normal circadian rhythm.