The potential therapeutic effect of melatonin in Gastro-Esophageal Reflux Disease

Revealing Melatonin's Mysteries: Receptors, Signaling Pathways, and Therapeutics Applications

Melatonin (5-methoxy-acetyl tryptamine) is a sleep-inducing hormone, and the pineal gland produces it in response to the circadian clock of darkness. In the body, MT1 and MT2 receptors are mostly found, having an orthosteric pocket and ligand binding determinants. Melatonin acts by binding on melatonin receptors, intracellular proteins, and orphan nuclear receptors. It inhibits adenyl cyclase and activates phospholipase C, resulting in gene expression and an intracellular alteration environment. Melatonin signaling pathways are also associated with other intracellular signaling pathways, i. e., cAMP/PKA and MAPK/ERK pathways. Relative expression of different proteins depends on the coupling profile of G protein, accounting pharmacology of the melatonin receptor bias system, and mediates action in a Gi-dependent manner. It shows antioxidant, antitumor, antiproliferative, and neuroprotective activity. Different types of melatonin agonists have been synthesized for the treatment of sleeping disorders. Researchers have developed therapeutics that target melatonin signaling, which could benefit a wide range of medical conditions. This review focuses on melatonin receptors, pharmacology, and signaling cascades; it aims to provide basic mechanical aspects of the receptor's pharmacology, melatonin's functions in cancer and neurodegenerative diseases, and any treatments and drugs designed for these diseases. This will allow a basic comparison between the receptors in question, highlighting any parallels and differences that may exist and providing fundamental knowledge about these receptors to future researchers.

Melatonin in hemicrania continua and paroxysmal hemicrania

BACKGROUND

Hemicrania continua (HC) and paroxysmal hemicrania (PH) belong to a group of primary headache disorders called trigeminal autonomic cephalalgias. One of the diagnostic criteria for both HC and PH is the absolute response to the therapeutic dose of indomethacin. However, indomethacin is discontinued in many patients as a result of intolerance to its side effects. Melatonin, a pineal hormone, which shares similar chemical structure to indomethacin, has been reported to have some efficacy for HC in previous case reports and series. To our knowledge, there is no literature regarding the use of melatonin in PH. We aimed to describe the clinical use of melatonin in the preventive management of HC and PH.

METHODS

Patient level data were extracted as an audit from routinely collected clinical records in consecutive patients seen in outpatient neurology clinic at King's College Hospital, London, UK, from September 2014 to April 2023. Our cohort of patients were identified through a search using the keywords: hemicrania continua, paroxysmal hemicrania, melatonin and indomethacin. Descriptive statistics including absolute and relative frequencies, mean ± SD, median and interquartile range (IQR) were used.

RESULTS

Fifty-six HC patients were included with a mean ± SD age of 52 ± 16 years; 43 of 56 (77%) patients were female. Melatonin was taken by 23 (41%) patients. Of these 23 patients, 19 (83%) stopped indomethacin because of different side effects. The doses of melatonin used ranged from 0.5 mg to 21 mg, with a median dose of 10 mg (IQR = 6-13 mg). Fourteen (61%) patients reported positive relief for headache, whereas the remaining nine (39%) patients reported no headache preventive effect. None of the patients reported that they were completely pain free. Two patients continued indomethacin and melatonin concurrently for better symptom relief. Eight patients continued melatonin as the single preventive treatment. Side effects from melatonin were rare. Twenty-two PH patients were included with mean ± SD age of 50 ± 17 years; 17 of 22 (77%) patients were female. Melatonin was given to six (27%) patients. The median dose of melatonin used was 8 mg (IQR = 6-10 mg). Three (50%) patients responded to melatonin treatment. One of them used melatonin as adjunctive treatment with indomethacin.

CONCLUSIONS

Melatonin showed some efficacy in the treatment of HC and PH with a well-tolerated side effect profile. It does not have the same absolute responsiveness as indomethacin, at the doses used, although it does offer a well-tolerated option that can have significant ameliorating effects in a substantial cohort of patients.

Is the Addition of Sublingual Melatonin to Omeprazole Superior to Omeprazole Alone in the Management of Gastroesophageal Reflux Disease Symptoms: A Clinical Trial

BACKGROUND/AIMS

Proton pump inhibitors are frequently used to treat gastroesophageal reflux disease, but their effect is restricted. The present study aimed to investigate whether the addition of sublingual melatonin to omeprazole was effective in the treatment of gastro gastroesophageal reflux disease symptoms.

MATERIALS AND METHODS

This was a randomized double-blind clinical trial. A total of 78 patients with gastro gastroesophageal reflux disease were randomly allocated to either omeprazole 20 mg/d plus sublingual melatonin (3 mg/d) or omeprazole 20 mg/d plus placebo for 4 weeks. The selected patients had histories of heartburn and regurgitation and a score ≤32 on the Frequency Scale for the Symptoms of gastroesophageal reflux disease (FSSG). The outcome measures for the assessment of treatment efficacy were heartburn, epigastric pain and the Frequency Scale for the Symptoms of gastroesophageal reflux disease score. Safety and quality of life were evaluated in the patients as the secondary outcomes too.

RESULTS

Seventy-two out of 78 eligible patients completed this trial (35 in the melatonin group and 37 in the placebo group). Heartburn, epigastric pain, and Frequency Scale for the Symptoms of gastroesophageal reflux disease score declined significantly in the melatonin group compared to the placebo group (P = .04, P = .03, and P = .0001, respectively). Moreover, the quality of life score was significantly higher in the melatonin group compared with the placebo group (P = .0001). Adverse events were similarly observed in the 2 groups (P = .55), and there were no serious adverse events.

CONCLUSION

The combination of sublingual melatonin (3 mg/day) with omeprazole (20 mg/day) may be more effective than omeprazole (20 mg/day) alone in the treatment of gastroesophageal reflux disease.

Is Melatonin the “Next Vitamin D”?: A Review of Emerging Science, Clinical Uses, Safety, and Dietary Supplements

Melatonin has become a popular dietary supplement, most known as a chronobiotic, and for establishing healthy sleep. Research over the last decade into cancer, Alzheimer’s disease, multiple sclerosis, fertility, PCOS, and many other conditions, combined with the COVID-19 pandemic, has led to greater awareness of melatonin because of its ability to act as a potent antioxidant, immune-active agent, and mitochondrial regulator. There are distinct similarities between melatonin and vitamin D in the depth and breadth of their impact on health. Both act as hormones, affect multiple systems through their immune-modulating, anti-inflammatory functions, are found in the skin, and are responsive to sunlight and darkness. In fact, there may be similarities between the widespread concern about vitamin D deficiency as a “sunlight deficiency” and reduced melatonin secretion as a result of “darkness deficiency” from overexposure to artificial blue light. The trend toward greater use of melatonin supplements has resulted in concern about its safety, especially higher doses, long-term use, and application in certain populations (e.g., children). This review aims to evaluate the recent data on melatonin’s mechanisms, its clinical uses beyond sleep, safety concerns, and a thorough summary of therapeutic considerations concerning dietary supplementation, including the different formats available (animal, synthetic, and phytomelatonin), dosing, timing, contraindications, and nutrient combinations.

Effectiveness of Nutritional Ingredients on Upper Gastrointestinal Conditions and Symptoms: A Narrative Review

Nutritional ingredients, including various fibers, herbs, and botanicals, have been historically used for various ailments. Their enduring appeal is predicated on the desire both for more natural approaches to health and to mitigate potential side effects of more mainstream treatments. Their use in individuals experiencing upper gastrointestinal (GI) complaints is of particular interest in the scientific space as well as the consumer market but requires review to better understand their potential effectiveness. The aim of this paper is to review the published scientific literature on nutritional ingredients for the management of upper GI complaints. We selected nutritional ingredients on the basis of mentions within the published literature and familiarity with recurrent components of consumer products currently marketed. A predefined literature search was conducted in Embase, Medline, Derwent drug file, ToXfile, and PubMed databases with specific nutritional ingredients and search terms related to upper GI health along with a manual search for each ingredient. Of our literature search, 16 human clinical studies including nine ingredients met our inclusion criteria and were assessed in this review. Products of interest within these studies subsumed the categories of botanicals, including fiber and combinations, and non-botanical extracts. Although there are a few ingredients with robust scientific evidence, such as ginger and a combination of peppermint and caraway oil, there are others, such as melatonin and marine alginate, with moderate evidence, and still others with limited scientific substantiation, such as galactomannan, fenugreek, and zinc-l-carnosine. Importantly, the paucity of high-quality data for the majority of the ingredients analyzed herein suggests ample opportunity for further study. In particular, trials with appropriate controls examining dose-response using standardized extracts and testing for specific benefits would yield precise and effective data to aid those with upper GI symptoms and conditions.

Sorting out the Relationship between Gastroesophageal Reflux Disease and Sleep

PURPOSE OF REVIEW

Gastroesophageal reflux disease is one of the most common conditions encountered by primary care physicians, gastroenterologists, foregut surgeons and otolaryngologists. While approximately 50% of patients experience nocturnal reflux symptoms, the relationship between gastroesophageal reflux disease and sleep is often overlooked. The aim of this review is to provide an update on the current understanding of this relationship and its clinical implications. Recent studies pertaining to the association between GERD and sleep with focus on sleep disturbances, obstructive sleep apnea, extraesophageal manifestations of GERD and treatment are discussed.

RECENT FINDINGS

There is a close relationship between GERD and sleep disturbances, but the nature of this relationship remains to be elucidated. Similarly, new data supports the association between GERD and obstructive sleep apnea, but whether this association is independent of confounding risk factors remains unresolved. Extraesophageal manifestations due to nocturnal GERD are primarily respiratory and can be explained by microaspiration and vagally-induced bronchospasm. Treatment of nocturnal GERD, both pharmacologically and surgically, improves sleep quality. Conversely, pharmacologic treatment of sleep disorders can improve nocturnal GERD symptoms. There is a bi-directional relationship between GERD and sleep. GERD is associated with various sleep disturbances. Sleep deficiency can exacerbate GERD. There is an association between extraesophageal manifestations and nocturnal GERD. Treatment directed towards GERD can improve sleep experience, and treatment directed to improve sleep can improve GERD symptoms.

Molecular targets for the management of gastrointestinal cancer using melatonin, a natural endogenous body hormone

Gastrointestinal cancer is one of the most common cancers globally. Melatonin, a natural endogenous body hormone, has been of interest for years, due to its anti-cancer characteristics, such as antiproliferative, antimetastatic, and cytotoxic as well as apoptotic induction. Through regulating several proteins such as melatonin upregulated mRNAs and proteins of downregulated Bcl-2-associated X protein (Bax), and B-cell lymphoma 2 (Bcl-2), as well as cytoplasmic protein such as calcium-binding proteins calmodulin or tubulin, and nuclear receptors, including RORα/RZR, and acts by non-receptor-regulated mechanisms, melatonin can exert anti-cancer efficacy. Moreover, melatonin modulates angiogenesis by targeting mRNA and protein expression of endothelin-converting enzyme (ECE-1) protein. In the present review, we address in vivo, in vitro and clinical reports on its anti-cancer efficacies, and the molecular mechanisms of action responsible for these effects. We advance the possibility of therapeutic melatonin administration for cancer therapy.

Rotating night shift work is associated with an increased risk of gastroesophageal reflux disease (GERD) symptoms among workers in China: A cross-sectional study

AIMS OF THE STUDY

Increasing studies suggest a significant association between night shift work and an increased risk of type 2 diabetes, obesity and other metabolic disorders. However, the available evidence of the association of rotating night shift work with gastroesophageal reflux disease (GERD) is limited. Herein, we hypothesised a link between the GERD risk and rotating night shift work among workers in China.

METHODS USED TO CONDUCT THE STUDY

A total of 2027 workers who completed a comprehensive health checkup were included. Logistic regression was used to investigate the link between rotating night shift work and the risk of GERD symptoms. Receiver operating characteristic (ROC) curve analysis was used to assess the multivariable model's diagnostic value for identifying GERD symptoms among workers.

RESULTS OF THE STUDY

In total, 556 (27.4%) individuals had GERD symptoms among 2027 workers. Multivariate analysis showed five independent factors for GERD: rotating night shift work (OR = 3.66, 95% CI: 2.52-5.40), age (OR = 2.53, 95% CI: 1.67-3.78), smoking (OR = 3.70, 95% CI: 2.63-5.21), Helicobacter pylori (H. pylori) infection (OR = 0.68, 95% CI: 0.48-0.96) and obesity (OR = 3.04, 95% CI: 2.43-3.83). A five-variable model based on five independent factors provided an area under a ROC curve (AUROC) of 0.80 (95% CI: 0.78-0.81) for identifying GERD symptoms among workers.

CONCLUSIONS DRAWN FROM THE STUDY AND CLINICAL IMPLICATIONS

Rotating night shift work is independently associated with an increased risk of GERD symptoms. Moreover a five-variable model (rotating night shift work, age, smoking, H pyori infection and obesity) can help identify individuals at high risk for GERD symptoms among workers in China.

When does proton pump inhibitor treatment become long term? A scoping review

Objective

Proton pump inhibitor (PPI) use has risen substantially, primarily driven by ongoing use over months to years. However, there is no consensus on how to define long-term PPI use. Our objectives were to review and compare definitions of long-term PPI use in existing literature and describe the rationale for each definition. Moreover, we aimed to suggest generally applicable definitions for research and clinical use.

Design

The databases PubMed and Cochrane Library were searched for publications concerning long-term use of PPIs and ClinicalTrials.gov was searched for registered studies. Two reviewers independently screened the titles, abstracts, and full texts in two series and subsequently extracted data.

Results

A total of 742 studies were identified, and 59 met the eligibility criteria. In addition, two ongoing studies were identified. The definition of long-term PPI use varied from >2 weeks to >7 years. The most common definition was ≥1 year or ≥6 months. A total of 12/61 (20%) of the studies rationalised their definition.

Conclusion

The definitions of long-term PPI treatment varied substantially between studies and were seldom rationalised.

In a clinical context, use of PPI for more than 8 weeks could be a reasonable definition of long-term use in patients with reflux symptoms and more than 4 weeks in patients with dyspepsia or peptic ulcer. For research purposes, 6 months could be a possible definition in pharmacoepidemiological studies, whereas studies of adverse effects may require a tailored definition depending on the necessary exposure time. We recommend to always rationalise the choice of definition.

Ex Vivo Electrochemical pH Mapping of the Gastrointestinal Tract in the Absence and Presence of Pharmacological Agents

Ex vivo pH profiling of the upper gastrointestinal (GI) tract (of a mouse), using an electrochemical pH probe, in both the absence and presence of pharmacological agents aimed at altering acid/bicarbonate production, is reported. Three pH electrodes were first assessed for suitability using a GI tract biological mimic buffer solution containing 0.5% mucin. These include a traditional glass pH probe, an iridium oxide (IrOx)-coated electrode (both operated potentiometrically), and a quinone (Q) surface-integrated boron-doped diamond (BDD-Q) electrode (voltammetric). In mucin, the time scale for both IrOx and glass to provide a representative pH reading was in the ∼100's of s, most likely due to mucin adsorption, in contrast to 6 s with the BDD-Q electrode. Both the glass and IrOx pH electrodes were also compromised on robustness due to fragility and delamination (IrOx) issues; contact with the GI tissue was an experimental requirement. BDD-Q was deemed the most appropriate. Ten measurements were made along the GI tract, esophagus (1), stomach (5), and duodenum (4). Under buffer only conditions, the BDD-Q probe tracked the pH from neutral in the esophagus to acidic in the stomach and rising to more alkaline in the duodenum. In the presence of omeprazole, a proton pump inhibitor, the body regions of the stomach exhibited elevated pH levels. Under melatonin treatment (a bicarbonate agonist and acid inhibitor), both the body of the stomach and the duodenum showed elevated pH levels. This study demonstrates the versatility of the BDD-Q pH electrode for real-time ex vivo biological tissue measurements.

Ranitidine Impairs Bone Healing and Implant Osseointegration in Rats' Tibiae

PURPOSE

Ranitidine has been found to have an impact on bone metabolism by suppressing osteoclastogenesis. We hypothesized that the use of ranitidine would impair bone healing and implant osseointegration. This study investigated the effect of postoperative administration of ranitidine on bone healing and osseointegration in rats.

MATERIALS AND METHODS

Twenty-two Sprague-Dawley rats underwent surgery to create a unicortical bone defect in each tibia. A titanium implant was placed on the right tibial defect, whereas the contralateral defect was left unfilled. After surgery, the rats were randomly divided into 2 groups receiving a daily dose of ranitidine or saline solution for 14 days and then euthanized for assessment of bone healing and osseointegration using micro-computed tomography (CT) and histomorphometry.

RESULTS

Micro-CT analysis of the bone defect showed a larger bone defect volume in the ranitidine group (0.82 ± 0.13 μL vs 0.66 ± 0.16 μL, P = .034), thinner cortical thickness (0.54 ± 0.07 mm vs 0.63 ± 0.11 mm, P = .026), and less bone regeneration at the defect site (40% ± 12% vs 57% ± 11%, P = .003). Implant-site micro-CT analysis showed less osseointegration in the ranitidine group (34.1% ± 2.7% vs 43.5% ± 2.1%, P = .014), and implant-site histologic analysis showed less medullary (P = .021), cortical (P = .001), and total (P = .003) bone-implant contact and less peri-implant bone volume-tissue volume (P = .002) in the ranitidine group. Histologic analysis for osteoclastic activity showed a lower number of osteoclasts in the ranitidine group (4.8 ± 2.4 mm^-2 vs 9.1 ± 2.1 mm^-2, P = .026).

CONCLUSIONS

The postoperative use of ranitidine impaired bone healing and osseointegration.

Popular Remedies for Esophageal Symptoms: a Critical Appraisal

PURPOSE OF REVIEW

Popular remedies are of ongoing interest to patients experiencing common esophageal symptoms, particularly as typical pharmacologic interventions have been subject to increased scrutiny. Herein we summarize the available data regarding potential risks and benefits of several such remedies.

RECENT FINDINGS

With emphasis on reflux and non-cardiac chest pain, research is ongoing into the clinical utility and diverse physiologic mechanisms underlying a variety of complementary and alternative modalities, including dietary manipulation, apple cider vinegar, melatonin, acupuncture, and various herbal products (rikkunshito, STW 5, slippery elm, licorice, and peppermint oil, among others). A substantial gap persists between anecdotal and empirical understandings of the majority of non-pharmacologic remedies for esophageal symptoms. This landscape of popular treatments nevertheless raises several interesting mechanistic hypotheses and compelling opportunities for future research.

Role of NRF2 in protection of the gastrointestinal tract against oxidative stress

The gastrointestinal tract is exposed to a variety of noxious factors, such as Helicobacter pylori, nonsteroidal anti-inflammatory drugs, gastric acid, ischemia-reperfusion, and mental stresses. Theses stressors generate free radicals within gastrointestinal tissues, causing organ injury and functional disturbance. Although the gastrointestinal tract can withstand such oxidative stresses to some extent by enhancing its antioxidant system via nuclear factor erythroid 2-related factor 2-Kelch-like erythroid cell-derived protein with CNC homology-associated protein 1-mediated pathways, acute or chronic exposure to oxidative stress can cause several gastrointestinal tract disorders, such as inflammation, ulcers, cancers, and various functional disturbances. Recent studies have demonstrated that some natural compounds and drugs can upregulate the nuclear factor erythroid 2-related factor 2-mediated antioxidant system, ameliorating or preventing these disorders. Although these compounds may be useful as chemopreventive agents, sufficient evidence for their clinical efficacy has not yet been provided. In addition, it is important to note that excessive nuclear factor erythroid 2-related factor 2 stimulation can be harmful to human health, especially from the standpoint of tumor biology.

Complementary and Integrative Gastroenterology

Complementary and integrative medicine is developing within gastroenterology, expanding options particularly for inflammatory bowel disease, irritable bowel syndrome, and reflux esophagitis. This article encompasses new developments in complementary integrative medicine with an emphasis on herbal therapies. Studies of potential therapies have been advancing with increasing sophistication. The best studied with the most promising results in ulcerative colitis is the use of curcumin both for the induction and maintenance of remission. Other polyphenols, such as resveratrol and epigallocatechin-3-gallate, also have supportive data for ulcerative colitis. Mind-body approaches have been applied in these diseases with positive data, particularly for irritable bowel syndrome.

Impact of night-shift work on the prevalence of erosive esophagitis in shipyard male workers

Purpose

Whether night-shift work is a risk factor for gastroesophageal reflux disease is controversial. The aim of this study was to investigate the association between night-shift work and other factors, and erosive esophagitis.

Methods

A cross-sectional study with 6040 male shipyard workers was performed. Esophagogastroduodenoscopic examination and a survey about night-shift work status, lifestyle, medical history, educational status, and marital status were conducted in all workers. The odds ratios of erosive esophagitis according to night-shift work status were calculated by using the logistic regression model.

Results

The prevalence of erosive esophagitis increased in the night-shift workers [odds ratio, 95 % confidence interval: 1.41 (1.03–1.94)]. According to multiple logistic regression models, night-shift work, obesity, smoking, and alcohol consumption of ≥140 g/week were significant risk factors for erosive esophagitis. By contrast, Helicobacter pylori infection was negatively associated with erosive esophagitis.

Conclusion

Night-shift work is suggested to be a risk factor for erosive esophagitis. Avoidance of night-shift work and lifestyle modification should be considered for prevention and management of gastroesophageal reflux disease.

The Effect of Ramelteon on Heartburn Symptoms of Patients With Gastroesophageal Reflux Disease and Chronic Insomnia: A Pilot Study

BACKGROUND

There is a bidirectional relationship between gastroesophageal reflux disease (GERD) and sleep. It has been demonstrated that antireflux treatment can improve sleep quality in GERD patients with nighttime reflux.

MATERIALS AND METHODS

Patients with heartburn and/or regurgitation ≥3 times/week and insomnia for ≥3 months were included. Patients were assessed at baseline with the demographic, GERD symptom assessment scale, Epworth sleepiness scale, Berlin sleep apnea, Pittsburgh sleep quality index, and the Insomnia severity index questionnaires. Subjects underwent an upper endoscopy followed by pH testing. Subsequently, subjects were randomized, in a double-blind, placebo-controlled trial, to receive either ramelteon 8 mg or placebo before bedtime for 4 weeks. During the last week of treatment, subjects completed a daily GERD symptom and sleep diary and underwent actigraphy.

RESULTS

Sixteen patients completed the study, 8 in each arm (mean age and M/F were 48.5 vs. 57.8 y, and 8/0 vs. 6/2, respectively). Patients who received ramelteon demonstrated a statistically significant decrease in symptom score as compared with those who received placebo for daytime heartburn (-42% vs. -29%), nighttime heartburn (-42% vs. 78%), 24-hour heartburn (-42% vs. -3%), and 24-hour acid regurgitation (-26% vs. 19%) (all P<0.05). Insomnia severity index score was significantly reduced in patients receiving ramelteon as compared with placebo (-46% vs. -5%, P<0.05). Ramelteon group also demonstrated a significant improvement in sleep efficiency and sleep latency, as compared with placebo, P<0.05). No significant adverse events were observed with ramelteon.

CONCLUSIONS

Ramelteon significantly improved symptoms in patients with GERD. In addition, ramelteon significantly improved patients' sleep experience. Further studies are needed in the future (NCT01128582).

Melatonin as a treatment for gastrointestinal cancer: a review

Gastrointestinal cancer is a disease that affects the population worldwide with high morbidity and mortality. Melatonin, an endogenously produced molecule, may provide a defense against a variety of cancer types. In particular, the ability of melatonin to inhibit gastrointestinal cancer is substantial. In this review, we first clarify the relationship between the disruption of the melatonin rhythm and gastrointestinal cancer (based on epidemiologic surveys and animal and human studies) and summarize the preventive effect of melatonin on carcinogenesis. Thereafter, the mechanisms through which melatonin exerts its anti-gastrointestinal cancer actions are explained, including inhibition of proliferation, invasion, metastasis, and angiogenesis, and promotion of apoptosis and cancer immunity. Moreover, we discuss the drug synergy effects and the role of melatonin receptors involved in the growth-inhibitory effects on gastrointestinal cancer. Taken together, the information compiled here serves as a comprehensive reference for the anti-gastrointestinal cancer actions of melatonin that have been identified to date and will hopefully aid in the design of further experimental and clinical studies and increase the awareness of melatonin as a therapeutic agent in cancers of the gastrointestinal tract.

Integrative Treatment of Reflux and Functional Dyspepsia in Children

Gastroesophageal reflux disease (GERD) and functional dyspepsia (FD) are common problems in the pediatric population, with up to 7% of school-age children and up to 8% of adolescents suffering from epigastric pain, heartburn, and regurgitation. Reflux is defined as the passage of stomach contents into the esophagus, while GERD refers to reflux symptoms that are associated with symptoms or complications-such as pain, asthma, aspiration pneumonia, or chronic cough. FD, as defined by the Rome III classification, is a persistent upper abdominal pain or discomfort, not related to bowel movements, and without any organic cause, that is present for at least two months prior to diagnosis. Endoscopic examination is typically negative in FD, whereas patients with GERD may have evidence of esophagitis or gastritis either grossly or microscopically. Up to 70% of children with dyspepsia exhibit delayed gastric emptying. Treatment of GERD and FD requires an integrative approach that may include pharmacologic therapy, treating concurrent constipation, botanicals, mind body techniques, improving sleep hygiene, increasing physical activity, and traditional Chinese medicine and acupuncture.

Esophagoprotection mediated by exogenous and endogenous melatonin in an experimental model of reflux esophagitis

Reflux esophagitis is a common clinical entity in western countries with approximately 30% of the population experiencing the symptoms at least once every month. The imbalance between the protective and aggressive factors leads to inflammation and damage of the esophageal mucosa. We compared the effect of exogenous melatonin and melatonin derived endogenously from L-tryptophan with that of pantoprazole or ranitidine in acid reflux esophagitis due to ligation of the rat pylorus and the limiting ridge between the forestomach and the corpus. Four hours after the induction of gastric reflux, an increase in mucosal lesions associated with edema of the submucosa and with the infiltration of numerous neutrophils and the fall in esophageal blood flow (EBF) were observed. Both melatonin and L-tryptophan or pantoprazole significantly reduced the lesion index (LI) and raised the EBF. Pinealectomy that significantly decreased plasma melatonin levels aggravated LI and these effects were reduced by melatonin and L-tryptophan. Luzindole, the MT2 receptor antagonist, abolished the melatonin-induced reduction in LI and the rise in EBF. L-NNA and capsaicin that augmented LI and decreased EBF, also significantly reduced melatonin-induced protection and hyperemia; both were restored with L-arginine and calcitonin gene-related peptide (CGRP) added to melatonin. Upregulation of IL-1β and TNF-α mRNAs and plasma IL-1β and TNF-α levels were significantly attenuated by melatonin and L-tryptophan. We conclude that melatonin protects against acid reflux-induced damage via activation of MT2 receptors mediated by NO and CGRP released from sensory nerves and the suppression of expression and release of TNF-α and IL-1β.

Expression of melatonin synthesizing enzymes in Helicobacter pylori infected gastric mucosa

Helicobacter pylori colonization of gastric mucosa causes pain of unknown etiology in about 15-20% of infected subjects. The aim of the present work was to determine the level of expression of enzymes involved in the synthesis of melatonin in gastric mucosa of asymptomatic and symptomatic H. pylori infected patients. To diagnose H. pylori infection, histological analysis and the urea breath test (UBT C13) were performed. The levels of mRNA expression of arylalkylamine-N-acetyltransferase (AA-NAT) and acetylserotonin methyltransferase (ASMT) were estimated in gastric mucosa with RT-PCR. The level of AA-NAT expression and AMST was decreased in H. pylori infected patients and was increased after H. pylori eradication. We conclude that decreased expression of melatonin synthesizing enzymes, AA-NAT and ASMT, in patients with symptomatic H. pylori infection returns to normal level after H. pylori eradication.

Does melatonin homeostasis play a role in continuous epigastric pain syndrome?

Two clinical forms of functional dyspepsia (FD) are listed in the Rome III criteria: postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS), differing in the recurrence of ailments depending on the diet. Continuous EPS (CEPS) is observed in some EPS patients, also at night, but its cause is still unknown. We showed previously that melatonin (MEL) homeostasis may be associated with FD. In the present work we evaluated selected components of melatonin homeostasis in patients with CEPS. The study included 30 patients with CEPS, 21 women and nine men, aged 21-49 years and 30 control subjects (EPS excluded); organic and mental diseases, as well as Helicobacter pylori infection, were excluded in both groups. The average severity of abdominal pain in the last three months was estimated in a 10-point scale (Visual Analog Scale). The levels of mRNA expression of arylalkylamine-N-acetyltransferase (AANAT) and hydroxyindole-O-methyltransferase (HIOMT), the main components of MEL homeostasis, were determined in gastric mucosa with real time PCR. The fasting serum level of MEL (at 09:00 a.m.) and circadian urine excretion of 6-sulfatoxymelatonin (6-HMS) were determined with ELISA. AANAT expression in antral mucosa of control subjects was 1.76 ± 0.41, in the gastric body 1.35 ± 0.38, and in the dyspeptic group 1.42 ± 0.38 (p < 0.05) and 0.92 ± 0.55 (p < 0.05), respectively. HIOMT expression in the control was 2.05 ± 0.70 in the antrum and 1.57 ± 0.69 in the body and in the CEPS group, it was: 1.51 ± 0.57 (p < 0.05) and 0.74 ± 0.31 (p < 0.001), respectively. MEL concentration (pg/mL) was 9.41 ± 3.09 in the control group and 5.62 ± 1.34 (p < 0.01) in the CEPS group. Urinary 6-HMS excretion (μg/24 h) was 11.40 ± 4.46 in the controls and 7.68 ± 2.88 (p < 0.05) in the CEPS. Moreover, a negative correlation was found between the tested parameters and severity of epigastric pain. These results indicate that patients with CEPS may display low level of AANAT and HIOMT expression in gastric mucosa, resulting in decreased MEL synthesis.

Which is the best choice for gastroesophageal disorders: Melatonin or proton pump inhibitors?

Melatonin is used in many countries to improve sleep disorders. Melatonin is a hormone produced by the pineal gland and enterochromaffin cells which control sleep and gastrointestinal motility. Low levels of melatonin lead to gastroesophageal reflux disease (GERD). Most of patients with GERD have a sleep disorder. So, low melatonin levels is the main cause of insomnia. Beyond this, it has an inhibitory action on gastric acid secretion and seems to control the lower esophageal sphincter. Proton pump inhibitors (PPIs) are a group of drugs whose main action is a pronounced and long-lasting reduction of gastric acid production. They are the most potent inhibitors of acid secretion available today. Omeprazole (one of the PPIs) and melatonin have similarities in their chemical structures. Therefore, we could consider omeprazole as a rough copy of melatonin. In this paper, we compare the advantages and disadvantages of the clinical use of melatonin and PPIs.

Advances in drug therapy for gastroesophageal reflux disease

The incidence of gastroesophageal reflux disease (GERD) is increasing drastically in China. GERD could probably cause reflux esophagitis, chronic cough, asthma, Barrett's esophagus and adenocarcinoma, and frequently affects health-related quality of life. The use of proton pump inhibitors (PPIs) provides effective symptomatic relief in most patients; however, some patients appear refractory to the treatment with PPIs. The long term use of PPIs might also cause adverse effects, such as interstitial nephritis, fracture and small intestinal bacterial overgrowth. Many new drugs for GERD have emerged recently. This article reviews the advances in drug therapy for GERD.

Melatonin independent protective role of l-tryptophan in experimental reflux esophagitis in rats

Melatonin is implicated in sustaining the esophageal integrity in gastro-esophageal reflux disease. However, the role of its synthetic precursor l-tryptophan is not clear in this pathology. The present study was designed to explore the effects of l-tryptophan on esophageal damage following reflux esophagitis (RE)-establishment and concurrent alterations in factors possibly influencing esophageal integrity such as esophageal melatonin level, luminal acidity, H(+)K(+)-ATPase activity, mucin and gastric PGE(2) levels. RE was established in rats by simultaneous ligation of pylorus region and fore-stomach. RE significantly decreased the esophageal-melatonin level and the expression of its synthesizing enzymes: arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT). Administration of l-tryptophan significantly decreased the RE-induced esophageal mucosal damage, without altering the levels of melatonin. l-Tryptophan pretreatment also normalized the esophageal mucosal damage caused by melatonin receptor antagonist-luzindole. Simultaneously, l-tryptophan significantly increased the RE-decreased expression of AA-NAT with insignificant effect on HIOMT gene expression. In contrast, l-tryptophan per se caused a significant elevation in the esophageal melatonin level, with no significant effect on the expression of AA-NAT and HIOMT enzymes. Further, l-tryptophan significantly normalized the RE-induced changes in the gastric juice volume, acidity and pH. However, it did not significantly inhibit the H(+)K(+)-ATPase activity in vitro. Also, l-tryptophan significantly increased the RE-reduced mucin level, COX-2 activity and thereby PGE(2) levels. Interestingly, indomethacin (PGE(2) synthesis blocker), aggravated the RE-induced tissue injury with simultaneous changes in the gastric volume, acidity, pH and mucin content, which l-tryptophan failed to reverse, suggesting that the attenuating effect of l-tryptophan on gastric secretions could be PGE(2) driven. Thus the current study provide evidences that protective functions of l-tryptophan against RE is independent of its conversion into melatonin, and possibly involve mobilization of factors such as COX-2 derived PGE(2) and mucin that counterbalance the detrimental effect of gastric acid on esophageal mucosa, signifying the therapeutic efficacy of l-tryptophan against the esophageal pathologies.

Which is the best choice for gastroesophageal disorders: Melatonin or proton pump inhibitors?

Melatonin is used in many countries to improve sleep disorders. Melatonin is a hormone produced by the pineal gland and enterochromaffin cells which control sleep and gastrointestinal motility. Low levels of melatonin lead to gastroesophageal reflux disease (GERD). Most of patients with GERD have a sleep disorder. So, low melatonin levels is the main cause of insomnia. Beyond this, it has an inhibitory action on gastric acid secretion and seems to control the lower esophageal sphincter. Proton pump inhibitors (PPIs) are a group of drugs whose main action is a pronounced and long-lasting reduction of gastric acid production. They are the most potent inhibitors of acid secretion available today. Omeprazole (one of the PPIs) and melatonin have similarities in their chemical structures. Therefore, we could consider omeprazole as a rough copy of melatonin. In this paper, we compare the advantages and disadvantages of the clinical use of melatonin and PPIs.