Melatonin supplementation ameliorates oxidative stress and inflammatory signaling induced by strenuous exercise in adult human males

Effects of different dietary supplements on athletic performance in soccer players: a systematic review and network meta-analysis

BACKGROUND

As dietary supplements play a crucial role in meeting the unique nutritional needs of soccer players, a growing body of studies are exploring the effects of dietary supplements on athletic performance in soccer players. The effectiveness of certain supplements, such as caffeine and creatine, remains debated due to inconsistent results across studies. Therefore, this systematic review and Bayesian network meta-analysis was conducted to tentatively identify the most effective dietary supplements for soccer players.

METHODS

We searched PubMed, Web of Science, Cochrane, Embase, and SPORTDiscus from database establishment to 5 February 2024 to identify randomized controlled trials (RCTs) evaluating the effects of different dietary supplements on athletic performance in soccer players. The risk of bias was assessed using the revised Cochrane risk-of-bias tool for randomized trials. A Bayesian network meta-analysis was performed using the R software and Stata 18.0. A subgroup analysis was conducted based on the competitive level of the athletes.

RESULTS

Eighty RCTs were included, with 1,425 soccer players randomly receiving 31 different dietary supplements or placebo. The network meta-analysis showed that compared with placebo, carbohydrate + protein (SMD: 2.2, very large), carbohydrate + electrolyte (SMD: 1.3, large), bovine colostrum (SMD: moderate) and caffeine (SMD: 0.29, small) were associated with a significant effect on increasing the distance covered. Kaempferia parviflora (SMD: 0.46, small) was associated with a significant effect on enhancing muscular strength. Beta-alanine (SMD: 0.83, moderate), melatonin (SMD: 0.75, moderate), caffeine (SMD: 0.37, small), and creatine (SMD: 0.33, small) were associated with a significant effect on enhancing jump height. Magnesium creatine chelate (SMD: -3.0, very large), melatonin (SMD: -1.9, large), creatine + sodium bicarbonate (SMD: -1.4, large), and arginine (SMD: -1.2, moderate) were associated with a significant effect on decreasing sprint time. Creatine + sodium bicarbonate (SMD: -2.3, very large) and caffeine (SMD: -0.38, small) were associated with a significant effect on improving agility. Sodium pyruvate (SMD: 0.50, small) was associated with a significant effect on increasing peak power. Magnesium creatine chelate (SMD: 1.3, large) and sodium pyruvate (SMD: 0.56, small) were associated with a significant effect on increasing mean power. Carbohydrate + electrolyte (SMD: -0.56, small) was associated with a significant effect on improving the rating of perceived exertion.

CONCLUSIONS

This study suggests that a range of dietary supplements, including caffeine, creatine, creatine + sodium bicarbonate, magnesium creatine chelate, carbohydrate + electrolyte, carbohydrate + protein, arginine, beta-alanine, bovine colostrum, Kaempferia parviflora, melatonin, and sodium pyruvate, can improve athletic performance in soccer players. This review provides evidence-based guidance for soccer coaches and nutritionists on using dietary supplements to enhance specific performance measures.

Melatonin, an Antitumor Necrosis Factor Therapy

Tumor necrosis factor (TNF) is a biomarker of inflammation whose levels are elevated in patients with several diseases associated with dysregulation of the immune response. The main limitations of currently used anti-TNF therapies are the induction of immunodepression, which in many cases leads to serious adverse effects such as infection and cancer, and the inability to cross the blood-brain barrier in neuroinflammatory conditions. Melatonin, in addition to being a chronobiotic compound, is widely known for its antioxidant and immunomodulatory capacity to control inflammatory processes in different pathological contexts. The aim of the present review is to address human-based studies that describe the effect of melatonin on TNF production. The review includes all the articles published in PubMed databases until April 15, 2024. After depuration, 45 studies were finally included in the review, 23 related to the in vitro action of melatonin in human cells and 22 in vivo studies in humans. Most of the data reviewed support the idea that melatonin has an immunosuppressive effect on TNF levels, which, together with its low toxicity profile, low cost, and ability to cross the blood-brain barrier, points to melatonin as a potential anti-TNF therapy. Therefore, improving our knowledge of the action of melatonin in regulating TNF through appropriate clinical trials would reveal the true potential of this molecule as a possible anti-TNF therapy.

Effects of Melatonin on Exercise-Induced Oxidative Stress in Adults with Obesity Undergoing a Multidisciplinary Body Weight Reduction Program

Background: Obesity is characterized by increased oxidative stress, which, in a vicious circle, promotes chronic low-grade inflammation. Melatonin, a well-documented antioxidant, might be useful as a supplement to enhance the cardiometabolic benefits of any body weight reduction program (BWRP). Objectives/Methods: The present study aimed to evaluate the post-exercise oxidative stress and inflammation in a group of subjects with obesity treated with melatonin (2 mg/die) or placebo, undergoing a 2-week BWRP, with the administration of a single bout of acute exercise at the start and the end of the protocol (G1-G15). Results: Eighteen adults with obesity were enrolled and distributed to the two arms of the study: the melatonin group (F/M: 7/2; age: 27.8 ± 5.6 years; body mass index [BMI]: 43.0 ± 4.9 kg/m2) and the placebo group (F/M: 6/3; age: 28.8 ± 5.0 years; BMI: 42.8 ± 4.0 kg/m2). BWRP induced a decrease in BMI and waist circumference (WC) in both groups; plasma glucose, blood glycated hemoglobin (HbA1c), and neutrophil to lymphocyte ratio (NLR) were reduced only in the placebo group. Importantly, plasma biological antioxidant potential (BAP) increased throughout BWRP. Paradoxically, melatonin enhanced post-exercise production of plasma derivatives of reactive oxygen metabolites (d-ROMs) and erythrocytic glutathionyl-Hb (HbSSG) (at G1 and G15). Finally, differently from the placebo group, melatonin-treated subjects did not exhibit the BWRP-induced decrease in plasma levels of interleukin-6 (IL-6), before and after exercise, at the end of two weeks (G15). Conclusions: Melatonin is presumably an antioxidant with "conditional" prooxidant actions. The use of melatonin as a supplement in subjects with obesity might be deleterious due to the abolishment of BWRP-induced cardiometabolic benefits.

Impact of Melatonin Supplementation on Sports Performance and Circulating Biomarkers in Highly Trained Athletes: A Systematic Review of Randomized Controlled Trials

Melatonin (N-acetyl-5 methoxytryptamine) is an indolic neurohormone that modulates a variety of physiological functions due to its antioxidant, anti-inflammatory, and immunoregulatory properties. Therefore, the purpose of this study was to critically review the effects of melatonin supplementation in sports performance and circulating biomarkers related to the health status of highly trained athletes. Data were obtained by performing searches in the following three bibliography databases: Web of Science, PubMed, and Scopus. The terms used were "Highly Trained Athletes", "Melatonin", and "Sports Performance", "Health Biomarkers" using "Humans" as a filter. The search update was carried out in February 2024 from original articles published with a controlled trial design. The PRISMA rules, the modified McMaster critical review form for quantitative studies, the PEDro scale, and the Cochrane risk of bias were applied. According to the inclusion and exclusion criteria, 21 articles were selected out of 294 references. The dose of melatonin supplemented in the trials ranged between 5 mg to 100 mg administered before or after exercise. The outcomes showed improvements in antioxidant status and inflammatory response and reversed liver damage and muscle damage. Moderate effects on modulating glycemia, total cholesterol, triglycerides, and creatinine were reported. Promising data were found regarding the potential benefits of melatonin in hematological biomarkers, hormonal responses, and sports performance. Therefore, the true efficiency of melatonin to directly improve sports performance remains to be assessed. Nevertheless, an indirect effect of melatonin supplementation in sports performance could be evaluated through improvements in health biomarkers.

Supplement Consumption by Elite Soccer Players: Differences by Competitive Level, Playing Position, and Sex

Soccer is a sport practiced all over the world and whose practice begins in young athletes. Currently, the consumption of nutritional supplements is essential to achieve the maximum performance of players. The aim of this study was to describe the consumption of sports supplements (CSS) by elite soccer players and its association with their competitive level, playing position, and sex. A comparative descriptive and non-experimental study was performed during the 2021-2022 competitive season. A total of 70 elite players completed one online questionnaire about their CSS. We found that sports drinks (55.7%), sports bars (50.0%), whey protein (48.6%), caffeine (47.1%), and creatine (60.0%) were the most consumed supplements by the total sample. Relative to the categories, the CSS was higher in the senior teams for both men and women. Regarding playing positions, caffeine was more consumed by midfielders and forwards (p = 0.013). Finally, in relation to sex, significant differences were found in the consumption of sports confectionery (p = 0.036), whey protein (p = 0.002), β-alanine (p = 0.013), and melatonin (p = 0.016). Soccer club SS questionnaires gather data to understand patterns, assess effectiveness and risks, and aid research. In conclusion, differences were found in the CSS according to competitive level, sex, and playing position.

Is melatonin as an ergogenic hormone a myth? a systematic review and meta-analysis

PURPOSE

Melatonin supplementation has been disclosed as an ergogenic substance. However, the effectiveness of melatonin supplementation in healthy subjects has not been systematically investigated. The present study analyzed the effects of melatonin supplementation on physical performance and recovery. In addition, it was investigated whether exercise bout or training alter melatonin secretion in athletes and exercise practitioners.

METHODS

This systematic review and meta-analysis were conducted and reported according to the guidelines outlined in the PRISMA statement. Based on the search and inclusion criteria, 21 studies were included in the systematic review, and 19 were included in the meta-analysis.

RESULTS

Melatonin supplementation did not affect aerobic performance relative to time trial (-0.04; 95% CI: -0.51 to 0.44) and relative to VO2 (0.00; 95% CI: -0.57 to 0.57). Also, melatonin supplementation did not affect strength performance (0.19; 95% CI: -0.28 to 0.65). Only Glutathione Peroxidase (GPx) secretion increased after melatonin supplementation (1.40; 95% CI: 0.29 to 2.51). Post-exercise melatonin secretion was not changed immediately after an exercise session (0.56; 95% CI: -0.29 to 1.41) and 60 min after exercise (0.56; 95% CI: -0.29 to 1.41).

CONCLUSION

The data indicate that melatonin is not an ergogenic hormone. In contrast, melatonin supplementation improves post-exercise recovery, even without altering its secretion.

Melatonin supplementation does not alter vascular function or oxidative stress in healthy normotensive adults on a high sodium diet

High sodium diets (HSD) can cause vascular dysfunction, in part due to increases in reactive oxygen species (ROS). Melatonin reduces ROS in healthy and clinical populations and may improve vascular function. The purpose was to determine the effect of melatonin supplementation on vascular function and ROS during 10 days of a HSD. We hypothesized that melatonin supplementation during a HSD would improve vascular function and decrease ROS levels compared to HSD alone. Twenty-seven participants (13 M/14 W, 26.7 ± 2.9 years, BMI: 23.6 ± 2.0 kg/m2 , BP: 110 ± 9/67 ± 7 mmHg) were randomized to a 10-day HSD (6900 mg sodium/d) supplemented with either 10 mg of melatonin (HSD + MEL) or a placebo (HSD + PL) daily. Brachial artery flow-mediated dilation, a measure of macrovascular function, (HSD + PL: 7.1 ± 3.8%; HSD + MEL: 6.7 ± 3.4%; p = 0.59) and tissue oxygenation index (TSI) reperfusion rate, a measure of microvascular reactivity, (HSD + PL: 0.21 ± 0.06%/s; HSD + MEL: 0.21 ± 0.08%/s; p = 0.97) and TSI area under the curve (HSD + PL: 199899 ± 10,863 a.u.; HSD + MEL: 20315 ± 11,348 a.u.; p = 0.17) were similar at the end of each condition. Neither nitroxide molarity (HSD + PL: 7.8 × 10-5  ± 4.1 × 10-5 mol/L; HSD + MEL: 8.7 × 10-5  ± 5.1 × 10-5 mol/L; p = 0.55) nor free radical number (HSD + PL: 8.0 × 1015  ± 4.4 × 1015 ; HSD + MEL: 9.0 × 1015  ± 4.9 × 1015 ; p = 0.51) were different between conditions. Melatonin supplementation did not alter vascular function or ROS levels while on a HSD in this sample of young healthy normotensive adults.

The Effects of Melatonin Supplementation on Professional Football Player Performance: A Systematic Review

BACKGROUND

Melatonin is a hormone that has shown anti-inflammatory actions, reduced oxidative stress, and has effects on physical performance, so the aim of this study was to review the effects of melatonin supplementation on the performance of professional soccer players.

METHODS

Critical and systematic review. Data were obtained by performing searches in the following bibliographic databases: Web of Science, MEDLINE (via PubMed), Embase, Cochrane Library, and Scopus. The terms used were "Soccer Athlete", "Melatonin", and "Soccer Performance", using "Humans" as a filter. The search update was in May 2023.

RESULTS

Having applied the inclusion and exclusion criteria, eight articles were selected out of 59 retrieved references. The dose of melatonin administered in the studies ranged between 5 and 8 mg. The outcomes showed a decrease in oxidative stress, muscle damage, and inflammatory markers in the melatonin-treated group.

CONCLUSIONS

Exogenously administered melatonin seems to attenuate some of the effects derived from physical exercise, such as oxidative stress, inflammation, and muscle damage, in professional football players, and since it has no potential adverse effects, it could be interesting to apply it in this population. However, the direct effects of melatonin supplementation on physical performance have not been demonstrated, so more research is needed on the intervention period and effective dose and with larger participant populations.

Antioxidant Capacity of Melatonin against Oxidative Stress Caused by Exercise-Induced Weight Loss in Rats

Antioxidant supplements such as melatonin are used to prevent oxidative stress during exercise. This study aimed to investigate the antioxidant capacity of melatonin supplementation against oxidative stress induced by the weight loss observed during exercise. Forty Wistar Albino male rats were subjected to 10 days of jogging exercises. Two groups were formed based on weight loss. Two subgroups were created in each group. Melatonin (5 mg/kg) was administered to each subgroup in each group. The other subgroups were designated as control subgroups. Blood samples were collected after 10 d. Superoxide dismutase (SOD), total antioxidant status (TAS), glutathione peroxidase, melatonin, and malondialdehyde levels were analyzed in blood samples. SOD, glutathione peroxidase, TAS, and melatonin levels in the melatonin subgroup were higher than those in the control subgroup in the non-weight loss group. In contrast, the malondialdehyde levels were lower. Melatonin levels in the melatonin subgroup were higher than those in the control subgroup in the weight loss group. Conversely, the SOD and TAS levels were lower. In addition, there was a positive correlation between weight loss and malondialdehyde levels and a negative correlation with SOD, TAS, and melatonin levels. Melatonin (5 mg/kg) supplementation showed antioxidant capacity in exercise without weight loss, but was insufficient in exercise with weight loss.

Melatonin Ingestion Prevents Liver Damage and Improves Biomarkers of Renal Function Following a Maximal Exercise

Background: While the promotion of the beneficial effects of melatonin (MEL) ingestion on the modulation of oxidative stress is widespread, less attention is given to the biological influence that it could exert on the results of hematology and clinical chemistry parameters. This study was undertaken to assess the effects of acute MEL ingestion on these parameters during a maximal running exercise. Methods: In double blind randomized design, 12 professional soccer players [age: 17.54 ± 0.78 yrs, body mass: 70.31 ± 3.86 kg, body height: 1.8 ± 0.08 m; maximal aerobic speed (MAS): 16.85 ± 0.63 km/h; mean ± standard deviation], all males, performed a diurnal (17:00 h ± 30 h) running exercise test (RET) at 100% of their MAS following either MEL or placebo ingestion. Blood samples were obtained at rest and following the RET. Results: Compared to placebo, MEL intake decreased post-exercise biomarkers of liver damage (aspartate aminotransferase, p<0.001; alanine aminotransferase, p<0.001; gamma-glutamyltransferase; p<0.05) and improved post-exercise renal function markers (i.e., creatinine, p<0.001). However, lipid profile, glucose, lactate and leukocyte were not affected by MEL ingestion. Regarding the time to exhaustion, no difference was found between MEL (362.46 ± 42.06 s) and PLA (374.54 ± 57.97 s) conditions. Conclusion: The results of this investigation clearly attest that MEL ingestion before a maximal running exercise might protect athletes from liver damage and perturbation in renal function biomarkers. However, this study comprises an acute MEL supplementation and no assessment on chronic effects or circadian rhythm the day before was done.

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.

Chitosan-sEPDM and Melatonin-Chitosan-sEPDM Composite Membranes for Melatonin Transport and Release

Melatonin is the hormone that focuses the attention of the researchers in the medical, pharmaceutical, materials, and membranes fields due to its multiple biomedical implications. The variety of techniques and methods for the controlled release of melatonin is linked to the multitude of applications, among which sports medicine occupies a special place. This paper presents the preparation and characterization of composite membranes based on chitosan (Chi) and sulfonated ethylene-propylene-diene terpolymer (sEPDM). The membranes were obtained by controlled vacuum evaporation from an 8% sEPDM solution in toluene (w/w), in which chitosan was dispersed in an ultrasonic field (sEPDM:Chi = 1:1, w/w). For the comparative evaluation of the membranes' performances, a melatonin-chitosan-sulfonated ethylene-propylene-diene terpolymer (Mel:Chi:sEPDM = 0.5:0.5:1.0, w/w/w) test membrane was made. The prepared membranes were morphologically and structurally characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive spectroscopy analysis (EDAX), thermal analysis (TG, DSC), thermal analysis coupled with chromatography and infrared analysis, and contact angle measurements, but also from the point of view of performance in the process of transport and release of melatonin in dedicated environments (aqueous solutions with controlled pH and salinity). The prepared membranes can release melatonin in amounts between 0.4 mg/cm²·per day (sEPDM), 1.6 mg/ cm²·per day (Chi/sEPDM), and 1.25 mg/cm²·per day (Mel/Chi/SEPDM).

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.

Antioxidative properties of phenolic compounds and their effect on oxidative stress induced by severe physical exercise

Extensive research has found strongly increased generation of reactive oxygen species, free radicals, and reactive nitrogen species during acute physical exercise that can lead to oxidative stress (OS) and impair muscle function. Polyphenols (PCs), the most abundant antioxidants in the human diet, are of increasing interest to athletes as antioxidants. Current literature suggests that antioxidants supplementation can effectively modulate these processes. This overview summarizes the actual knowledge of chemical and biomechanical properties of PCs and their impact as supplements on acute exercise-induced OS, inflammation control, and exercise performance. Evidence maintains that PC supplements have high potency to positively impact redox homeostasis and improve skeletal muscle's physiological and physical functions. However, many studies have failed to present improvement in physical performance. Eleven of 15 representative experimental studies reported a reduction of severe exercise-induced OS and inflammation markers or enhancement of total antioxidant capacity; four of eight studies found improvement in exercise performance outcomes. Further studies should be continued to address a safe, optimal PC dosage, supplementation timing during a severe training program in different sports disciplines, and effects on performance response and adaptations of skeletal muscle to exercise.

Melatonin alleviates the immune response and improves salivary gland function in primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is an autoimmune disease that primarily affects exocrine glands and is characterized by sicca syndrome and systemic manifestation. Mounting evidence indicates that circadian clocks are involved in the onset and progression of autoimmune diseases, including rheumatic arthritis, multiple sclerosis, and systemic lupus erythematosus. However, few studies have reported the expression of clock genes in pSS. There is no ideal therapeuticmethod for pSS, the management of pSS is mainly palliative, aims to alleviate sicca symptoms. Melatonin is a neuroendocrine hormone mainly secreted by the pineal gland that plays an important role in the maintenance of the circadian rhythm and immunomodulation. Hence, this study aimed to analyse the circadian expression profile of clock genes in pSS, and further evaluate the therapeutic potential of melatonin in pSS. We discovered a distinct clock gene expression profile in an animal model and in patients with pSS. More importantly, melatonin administration regulated clock gene expression, improved the hypofunction of the salivary glands, and inhibited inflammatory development in animal model of pSS. Our study suggested that the pathogenesis of pSS might correlate with abnormal expression of circadian genes, and that melatonin might be a potential candidate for prevention and treatment of pSS.

Melatonin reduces muscle damage, inflammation and oxidative stress induced by exhaustive exercise in people with overweight/obesity

BACKGROUND

Intense physical exercise leads to inflammation, oxidative stress and muscle damage, and these responses are of greater magnitude in people with obesity. Melatonin (MLT) is considered an endogenous antioxidant which may have beneficial effects against inflammation, oxidative stress and promote tissue repair after exercise. The aim of this study was to examine the effect of MLT on inflammatory parameters, oxidative stress and muscle damage in people with overweight/obesity after a high-intensity interval exercise (HIIE).

METHODS

A total of 23 subjects with obesity (9 men and 14 women) age: 33.26 ± 9.81 years, BMI: 37.75 ± 8.87 kg.m-2 were randomized to participate in two experimental sessions: HIIE + Placebo and HIIE + MLT (3 mg). The HIIE protocol corresponds to 8 intervals of 1 min (90% of the maximal aerobic power (MAP)) alternating with 2 min recovery (45% of the MAP). Blood samples were drawn before and 5 min after each exercise session.

RESULTS

MLT ingestion attenuated the increase of inflammation (C-reactive protein, white blood cells (P < 0.001, ηp2 = 0.45; for both) and Neutrophils (P < 0.01, ηp2 = 0.36)) and hepatic and muscle damage (Aspartate aminotransferase (P < 0.01, ηp2 = 0.25), Alanine aminotransferase (P < 0.01, ηp2 = 0.27) and Creatine kinase (P = 0.02, ηp2 = 0.23). MLT also attenuated the exercise induced lipid and protein peroxidation (i.e., Malondialdehyde (P = 0.03, ηp2 = 0.19) and AOPP (P < 0.001, ηp2 = 0.55)). Concerning the antioxidant status, MLT intake increased Thiol (P < 0.01, ηp2 = 0.26) and Catalase (P < 0.01, ηp2 = 0.32) and decreased Uric acid (P = 0.02, ηp2 = 0.2) and Total bilirubin (P < 0.01, ηp2 = 0.33).

CONCLUSIONS

MLT intake before HIIE reduced muscle damage by modulating oxidative stress and preventing overexpression of the pro-inflammatory mediators in people with obesity.

Effects of melatonin ingestion on physical performance and biochemical responses following exhaustive running exercise in soccer players

Antioxidant supplementation has become a common practice among athletes to boost sport achievement. Likewise, melatonin (MEL) has been ingested as an ergogenic aid to improve physical performance. To date, no study has checked whether the multiple beneficial effects of MEL have an outcome during a maximum running exercise until exhaustion. Therefore, the present study aimed to evaluate the effect of MEL ingestion on physical performance and biochemical responses (i.e., oxidative stress) during exhaustive exercise. In a double blind randomized study, thirteen professional soccer players [age: 17.5 ± 0.8 years, body mass: 70.3 ± 3.9 kg, body height: 1.80 ± 0.08 m; maximal aerobic speed (MAS): 16.85 ± 0.63 km/h; mean ± standard deviation], members of a first league squad, performed a running exercise until exhaustion at 100% of MAS, after either MEL or placebo ingestion. Physical performance was assessed, and blood samples were obtained at rest and following the exercise. Compared to placebo, MEL intake prevented the increase in oxidative stress markers (i.e., malondialdehyde), alleviated the alteration of antioxidant status (i.e., glutathione peroxidase, uric acid and total bilirubin) and decreased post-exercise biomarkers of muscle damage (i.e., creatine kinase and lactate dehydrogenase) (p < 0.05). However, physical performance was not affected by MEL ingestion (p > 0.05). In conclusion, acute MEL intake before a maximal running exercise protected athletes from oxidative stress and cellular damage but without an effect on physical performance.

Exogenous Melatonin Alleviates Skeletal Muscle Wasting by Regulating Hypothalamic Neuropeptides Expression in Endotoxemia Rats

To investigate whether exogenous melatonin (MLT) could alleviate skeletal muscle wasting by regulating hypothalamic neuropeptides expression. Adult male Sprague Dawley rats were intraperitoneally injected with lipopolysaccharide (LPS) (10 mg/kg), followed by MLT (30 mg/kg/day) or saline for 3 days. Hypothalamic tissues and skeletal muscle were obtained on day 3. Skeletal muscle wasting was measured by the mRNA expression of two E3 ubiquitin ligases, muscle atrophy F-box and muscle ring finger 1 as well as 3-methylhistidine (3-MH) and tyrosine release. Three hypothalamic neuropeptides (POMC, AgRP, CART) expression were detected in all groups. POMC expression knockdown was achieved by ARC injection of lentiviruses containing shRNA against POMC. Two weeks after ARC viruses injection, rats were i.p. injected with LPS (10 mg/kg) followed by MLT (30 mg/kg/day) or saline for 3 days. Brain tissues were harvested for immunostaining. In septic rats, 3-MH, tyrosine release and muscle atrophic gene expression were significantly decreased in MLT treated group. POMC and CART expression were lower while AgRP expression was higher in MLT treated group. Furthermore, in septic rats treated with MLT, muscle wasting in those with lower expression of neuropeptide POMC did not differ from those with normal POMC expression. Exogenous MLT could alleviate skeletal muscle wasting in septic rats by regulating hypothalamic neuropeptides.

Assessment of Stress Salivary Markers, Perceived Stress, and Shift Work in a Cohort of Fishermen: A Preliminary Work

Due to work-related stress, today, work itself represents a daily challenge that must be faced in many occupations. While, in the past, the scientific community has focused on the helping professions, since, an increasing number of professions have since been investigated. Therefore, different approaches exist in order to assess this disorder, representing a scientific field wherein biological and psychological dimensions both need to be evaluated. In this paper, we consider three biological salivary markers: interleukin 1 beta (IL-1β), cortisol, and melatonin. The choice derives from recent contributions to the literature in which the interplay between these markers has been verified. Briefly, such interplay could explain how the central nervous, endocrine, and immune systems communicate with each other, supporting a holistic concept of person. In 30 marine fishermen from the Apulia region of Italy, perceived stress was measured using the Professional Stress Scale (PSS) and sleep disturbances were assessed through the Pittsburgh Sleep Quality Index (PSQI). Salivary markers were collected at 8:00 a.m. and 2:00 p.m. Those subjects reporting sleep disturbance and having altered scores in two PSS subclasses, home-work conflict and self-esteem, presented inverted salivary melatonin and cortisol nictemeral rhythms (with regard to melatonin levels at 8:00 a.m., those workers reporting values higher than the median showed 64.1% versus 48.6% home-work conflict with respect to cortisol levels, subjects having an inverted circadian rhythm showed 69.9% versus 52.5% home-work conflict, and these values resulted 47.7% versus 25.3% when the self-esteem was considered). As regards melatonin, PSQI score is statistically different in the two groups of subjects as identified by median melatonin at 8:00 a.m.; specifically, the subjects who had mean values higher than the median shared higher PSQI scores (10.8 versus 9.8). The same subjects reported more frequent home-work conflict and more sleep disorders. We found a negative correlation between IL-1β at 8:00 a.m. and Cortdiff (the difference between cortisol at 8:00 a.m.-cortisol at 2:00 p.m.), and that high IL-1β at 8:00 a.m. was associated with low Cortdiff. Based on our results we would like to propose this approach in health surveillance, in order to prevent mental and/or physical disorders, however our study is surely preliminary. The interesting perspectives and hypotheses cited in this paper, in which the roles of IL-1β and norepinephrine appear central and important, could remain hypothetical if not supported by more robust observation in order to produce, truly, new knowledge. In the future we will deepen this study with a larger sample, and if these results will be confirmed, this approach could allow preventing, not only mental and physical disorders, but also immuno-mediated diseases, and, perhaps, cancer.

Exercise-induced oxidative stress and melatonin supplementation: current evidence

Melatonin possesses the indoleamine structure and exerts antioxidant and anti-inflammatory actions and other physiological properties. Physical exercise can influence secretion of melatonin. Melatonin is used as a natural supplement among athletes to regulate sleep cycles and protect muscles against oxidative damage. Despite decades of research, there is still a lack of a comprehensive and critical review on melatonin supplementation and physical activity relationship. The aim of this literature review is to examine the antioxidant, anti-inflammatory and other biological functions played by melatonin with reference to the effect of physical exercise on melatonin secretion and the effect of this compound supplementation on exercise-induced oxidative stress in athletes. Evidence shows that intense exercises disturb antioxidant status of competitive athletes, whereas supplementation with melatonin strengthens antioxidant status in trained athletes in various sports as the compound showed high potency in reduction of the oxidative stress and inflammation markers generated during intense and prolonged exercise.

Differential response of diurnal and nocturnal mammals to prolonged altered light-dark cycle: a possible role of mood associated endocrine, inflammatory and antioxidant system

The circadian system maintains internal 24 h oscillation of behavior and physiology, and its misalignment with external light-dark (LD) cycle results in negative health outcomes. In order to elucidate the effect of prolonged constant condition and the differences in the response between nocturnal and diurnal species, we studied the effects of constant light (LL) and constant darkness (DD) on a diurnal (squirrel) and a nocturnal (mouse) rodent species, focusing on the endocrine, inflammatory and antioxidant systems associated with depression-like behavior. Squirrels and mice (n = 10/group) were placed in chronocubicle under 12:12 h LD cycle, LL and DD. After 4 weeks, animals were subjected to sucrose preference test and blood and brain tissues were collected for measuring melatonin, corticosterone, proinflammatory cytokine, tumor necrosis factor-α (TNF-α) and the activity of primary antioxidant enzymes, catalase (CAT) and superoxide dismutase (SOD). The results show that in diurnal squirrels, prolonged constant darkness reduced sucrose preference, CAT, and SOD, increased corticosterone and TNF-α levels, but caused no significant change in the melatonin compared to LD condition. In contrast, in nocturnal mice constant darkness caused no significant changes in sucrose preference and corticosterone levels, increased melatonin, CAT and SOD levels but decreased TNF-α levels. Chronic LL caused a similar response in both squirrels and mice: it decreased sucrose preference, melatonin, CAT and SOD levels but increased corticosterone and TNF-α levels. Together, the study demonstrates differential effects of altered light-dark cycle in a diurnal and a nocturnal rodent on interrelated endocrine, inflammatory and antioxidant systems associated with depression-like behavior, with constant light having adverse effects on both species but constant darkness having a negative effect mainly in the diurnal squirrels.

The role of melatonin in sarcopenia: Advances and application prospects

Sarcopenia is an age-related disease that has gradually become a serious health problem for elderly individuals. It not only greatly increases the risk of falls, weakness, and disability but also reduces the ability of patients to take care of themselves. Sarcopenia can directly affect the quality of life and disease prognosis of elderly individuals. However, drug interventions for this disease are lacking. Melatonin is a biological hormone produced by the body that has good free radical scavenging effects, antioxidant effects and other effects. It was originally used as a sleep aid and is now being used for an increasing number of new indications. Its effect on sarcopenia has also begun to attract attention. It is currently known that it can protect the mitochondria of skeletal muscle cells, maintain the number of muscle fibres, partially reverse the pathological changes of ageing muscle tissue, and increase muscle strength in patients with sarcopenia. A large number of microRNAs are expressed during cell ageing, that in turn provides a biological background to age-related diseases, like sarcopenia. Increasing studies have found an interaction between melatonin and miRNAs, suggesting that melatonin can be used in the treatment of sarcopenia. The increased expression of inflammation-associated miRNA-483 in elderly patients may be the basis for the age-dependent decrease in melatonin secretion，that may play a role in the morbidity of sarcopenia. Melatonin is closely related to sarcopenia. It has a wide range of effects on sarcopenia and has good application prospects for the prevention and treatment of sarcopenia.

Anti-inflammatory effects of melatonin: A systematic review and meta-analysis of clinical trials

Chronic inflammation contributes to multiple diseases including cardiovascular diseases, autoimmune disorders, metabolic disorders, and psychiatric conditions. Melatonin, a hormone responsible for circadian rhythm, plays a complex role within the immune system, including having an anti-inflammatory effect. While there are numerous animal studies demonstrating this effect, few human clinical trials have been conducted. This systematic review of clinical trials examined whether exogenous melatonin reduces levels of inflammatory markers in humans. We searched PubMed, Embase, Cochrane Library, Scopus, and PsycINFO, and the references of the identified articles for randomized and non-randomized placebo-controlled trials. Data were extracted from the articles and meta-analyses were conducted using a random effects model to calculate standardized mean differences (SMDs, i.e., Cohen's d). From an initial search result of 4548 references, 31 studies met the inclusion criteria and were included involving 1517 participants. Melatonin had significant anti-inflammatory effects on interleukin (IL)-1 (SMD -1.64; 95% confidence interval [CI] -2.86, -0.43; p = 0.008), IL-6 (-3.84; -5.23, -2.46; p < 0.001), IL-8 (-21.06; -27.27, -14.85; p < 0.001), and tumor necrosis factor (TNF) (-1.54; -2.49, -0.58; p = 0.002), but not on C-reactive protein (CRP) (-0.18; -0.91, 0.55; p = 0.62). Trimming outlier studies with large effect sizes eliminated publication bias, and summary effect sizes were significant for IL-1 (SMD -1.11; 95% CI -1.90, -0.32; p = 0.006), IL-6 (-1.91; -2.98, -0.83; p = 0.001), and IL-8 (-13.46; -18.88, -8.04; p < 0.001), but not for TNF (-0.45; -1.13, 0.23; p = 0.19). Exogenous melatonin reduced levels of inflammatory markers and may be useful for prevention and adjuvant treatment of inflammatory disorders. Melatonin is safe with few side effects, which makes it an excellent agent for prevention of inflammatory disorders. Because chronic inflammation increases with aging and inflammation plays a role in the etiology of numerous diseases that affect older populations, melatonin has the potential to be widely used particularly in older adults.

Molecular links between endocrine, nervous and immune system during chronic stress

INTRODUCTION

The stress response is different in various individuals, however, the mechanisms that could explain these distinct effects are not well known and the molecular correlates have been considered one at the time. Particular harmful conditions occur if the subject, instead to cope the stressful events, succumb to them, in this case, a cascade reaction happens that through different signaling causes a specific reaction named "sickness behaviour." The aim of this article is to review the complex relations among important molecules belonging to Central nervous system (CNS), immune system (IS), and endocrine system (ES) during the chronic stress response.

METHODS

After having verified the state of art concerning the function of cortisol, norepinephrine (NE), interleukin (IL)-1β and melatonin, we describe as they work together.

RESULTS

We propose a speculative hypothesis concerning the complex interplay of these signaling molecules during chronic stress, highlighting the role of IL-1β as main biomarker of this effects, indeed, during chronic stress its increment transforms this inflammatory signal into a nervous signal (NE), in turn, this uses the ES (melatonin and cortisol) to counterbalance again IL-1β. During cortisol resistance, a vicious loop occurs that increments all mediators, unbalancing IS, ES, and CNS networks. This IL-1β increase would occur above all when the individual succumbs to stressful events, showing the Sickness Behaviour Symptoms. IL-1β might, through melatonin and vice versa, determine sleep disorders too.

CONCLUSION

The molecular links here outlined could explain how stress plays a role in etiopathogenesis of several diseases through this complex interplay.

Rapid Liquid Chromatography-Tandem Mass Spectrometry Analysis of Two Urinary Oxidative Stress Biomarkers: 8-oxodG and 8-isoprostane

Human biomonitoring of oxidative stress relies on urinary effect biomarkers such as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), and 8-iso-prostaglandin F2α (8-isoprostane); however, their levels reported for similar populations are inconsistent in the scientific literature. One of the reasons is the multitude of analytical methods with varying degrees of selectivity used to quantify these biomarkers. Single-analyte methods are often used, requiring multiple injections that increase both time and cost. We developed a rapid ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method to quantify both urinary biomarkers simultaneously. A reversed-phase column using a gradient consisting of 0.1% acetic acid in water and 0.1% acetic acid in methanol/acetonitrile (70:30) was used for separation. The MS detection was by positive (8-oxodG) and negative (8-isoprostane) ion-mode by multiple reaction monitoring. Very low limit of detection (<20 pg/mL), excellent linearity (R2 > 0.999), accuracy (near 100%), and precision (CV < 10%) both for intra-day and inter-day experiments were achieved, as well as high recovery rates (>91%). Matrix effects were observed but were compensated by using internal standards. Our newly developed method is applicable for biomonitoring studies as well as large epidemiological studies investigating the effect of oxidative damage, as it requires only minimal clean up using solid phase extraction.

A Short Overview of Changes in Inflammatory Cytokines and Oxidative Stress in Response to Physical Activity and Antioxidant Supplementation

Excessive release of inflammatory cytokines and oxidative stress (OS) are triggering factors in the onset of chronic diseases. One of the factors that can ensure health in humans is regular physical activity. This type of activity can enhance immune function and dramatically prevent the spread of the cytokine response and OS. However, if physical activity is done intensely at irregular intervals, it is not only unhealthy but can also lead to muscle damage, OS, and inflammation. In this review, the response of cytokines and OS to exercise is described. In addition, it is focused predominantly on the role of reactive oxygen and nitrogen species (RONS) generated from muscle metabolism and damage during exercise and on the modulatory effects of antioxidant supplements. Furthermore, the influence of factors such as age, sex, and type of exercise protocol (volume, duration, and intensity of training) is analyzed. The effect of antioxidant supplements on improving OS and inflammatory cytokines is somewhat ambiguous. More research is needed to understand this issue, considering in greater detail factors such as level of training, health status, age, sex, disease, and type of exercise protocol.

Antioxidant supplements and endurance exercise: Current evidence and mechanistic insights

Antioxidant supplements are commonly consumed by endurance athletes to minimize exercise-induced oxidative stress, with the intention of enhancing recovery and improving performance. There are numerous commercially available nutritional supplements that are targeted to athletes and health enthusiasts that allegedly possess antioxidant properties. However, most of these compounds are poorly investigated with respect to their in vivo redox activity and efficacy in humans. Therefore, this review will firstly provide a background to endurance exercise-related redox signalling and the subsequent adaptations in skeletal muscle and vascular function. The review will then discuss commonly available compounds with purported antioxidant effects for use by athletes. N-acetyl cysteine may be of benefit over the days prior to an endurance event; while chronic intake of combined 1000 mg vitamin C + vitamin E is not recommended during periods of heavy training associated with adaptations in skeletal muscle. Melatonin, vitamin E and α-lipoic acid appear effective at decreasing markers of exercise-induced oxidative stress. However, evidence on their effects on endurance performance are either lacking or not supportive. Catechins, anthocyanins, coenzyme Q10 and vitamin C may improve vascular function, however, evidence is either limited to specific sub-populations and/or does not translate to improved performance. Finally, additional research should clarify the potential benefits of curcumin in improving muscle recovery post intensive exercise; and the potential hampering effects of astaxanthin, selenium and vitamin A on skeletal muscle adaptations to endurance training. Overall, we highlight the lack of supportive evidence for most antioxidant compounds to recommend to athletes.

Effect of nocturnal melatonin intake on cellular damage and recovery from repeated sprint performance during an intensive training schedule

An optimal recovery between training sessions is of similar if not greater importance as the training content and program of the training, itself. One of the most used strategies for improving recovery is the ingestion of supplements. The present study aimed to evaluate the effect of 5 mg oral melatonin supplementation on the recovery from repeated sprint (RSA) of performance and biochemical responses (i.e. oxidative stress, leukocytosis cellular damage) after an intensive training camp (TC). Twenty soccer players performed an RSA test before and after an intensive six-day TC associated with nocturnal melatonin (n = 10) or placebo (n = 10) ingestion. Resting and post-RSA test blood samples were obtained before and after the TC. Compared to placebo, melatonin intake decreased resting oxidative stress markers (i.e, advanced oxidation protein products), leukocytosis (i.e. white blood cells (WBC), neutrophils (NE)) and biomarkers of cellular damage (i.e. creatine kinase (CK)). It also lowered post-exercise leukocytosis (i.e. WBC, NE, lymphocytes (LY), monocytes (MO)) and biomarkers of cellular damage (i.e. CK, aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT)) and raised the activity of the main antioxidant enzymes (i.e. glutathione peroxidase (GPx), glutathione reductase (GR)). In addition, compared to placebo, melatonin reduced the deterioration of the best and total time during the RSA test after the TC. In conclusion, nocturnal melatonin supplementation during an intensive TC alleviated oxidative stress, leukocytosis and cellular damage and improved recovery of RSA performance in soccer players.

Impact of Melatonin on Skeletal Muscle and Exercise

Skeletal muscle disorders are dramatically increasing with human aging with enormous sanitary costs and impact on the quality of life. Preventive and therapeutic tools to limit onset and progression of muscle frailty include nutrition and physical training. Melatonin, the indole produced at nighttime in pineal and extra-pineal sites in mammalians, has recognized anti-aging, anti-inflammatory, and anti-oxidant properties. Mitochondria are the favorite target of melatonin, which maintains them efficiently, scavenging free radicals and reducing oxidative damage. Here, we discuss the most recent evidence of dietary melatonin efficacy in age-related skeletal muscle disorders in cellular, preclinical, and clinical studies. Furthermore, we analyze the emerging impact of melatonin on physical activity. Finally, we consider the newest evidence of the gut-muscle axis and the influence of exercise and probably melatonin on the microbiota. In our opinion, this review reinforces the relevance of melatonin as a safe nutraceutical that limits skeletal muscle frailty and prolongs physical performance.

Effects of Melatonin on the Body Composition, Physical Performance, and Blood Erythrocyte Indexes of C57Bl/6J Mice Exposed to Continuous Illumination

Male C57Bl/6J mice were exposed to daily 24-h illumination over 14 days and daily intragastrically received melatonin (1 mg/kg) or water (placebo). Controls were kept under standard day/night (14/10 h) conditions. Melatonin prevented the development of anemia in mice exposed to continuous illumination, which was proven by higher blood hemoglobin levels by the end of the experiment in melatonin-treated animals in comparison with the placebo group. Studies by the low-field NMR spectrometry detected lower lean body mass, total body water, and especially, fat content (by ~13%) in animals receiving placebo. Melatonin treatment led to an increase in the lean body mass and total body water on day 7 (in comparison with the placebo group) without affecting fat mass. On day 14 of continuous illumination, lean body mass increased in comparison with the corresponding parameter in the control and placebo groups. Melatonin had no effect on the physical endurance of mice exposed to continuous illumination (assessed by the grid hanging test).

Rotating night shift work and risk of multiple sclerosis in the Nurses' Health Studies

OBJECTIVES

Night shift work has been suggested as a possible risk factor for multiple sclerosis (MS). The objective of the present analysis was to prospectively evaluate the association of rotating night shift work history and MS risk in two female cohorts, the Nurses' Health Study (NHS) and NHSII.

METHODS

A total of 83 992 (NHS) and 114 427 (NHSII) women were included in this analysis. We documented 579 (109 in NHS and 470 in NHSII) incident physician-confirmed MS cases (moderate and definite diagnosis), including 407 definite MS cases. The history (cumulative years) of rotating night shifts (≥3 nights/month) was assessed at baseline and updated throughout follow-up. Cox proportional hazards models were used to estimate HRs and 95% CIs for the association between rotating night shift work and MS risk adjusting for potential confounders.

RESULTS

We observed no association between history of rotating night shift work and MS risk in NHS (1-9 years: HR 1.03, 95% CI 0.69 to 1.54; 10+ years: 1.15, 0.62 to 2.15) and NHSII (1-9 years: HR 0.90, 95% CI 0.74 to 1.09; 10+ years: 1.03, 0.72 to 1.49). In NHSII, rotating night shift work history of 20+ years was significantly associated with MS risk, when restricting to definite MS cases (1-9 years: HR 0.88, 95% CI 0.70 to 1.11; 10-19 years: 0.98, 0.62 to 1.55; 20+ years: 2.62, 1.06 to 6.46).

CONCLUSIONS

Overall, we found no association between rotating night shift work history and MS risk in these two large cohorts of nurses. In NHSII, shift work history of 20 or more years was associated with an increased risk of definite MS diagnosis.

Melatonin treatment of pigs with acute pancreatitis reduces inflammatory reaction of pancreatic tissue and enhances fitness score of pigs: experimental research

Background

Severe acute pancreatitis is associated with high morbidity and mortality. Melatonin is known as the activator of antioxidant enzymes. The main purpose of this study was to evaluate the clinical effect of melatonin treatment in a pig model with induced acute pancreatitis.

Methods

In this study, acute pancreatitis was induced in 38 German domestic pigs (German Hybrid). After induction of acute pancreatitis, 18 animals were treated with melatonin. Intraoperative clinical data, postoperative blood parameters, fitness, and Porcine Well-being (PWB) score, and post-mortal histopathological data were analyzed in both study groups.

Results

The matching procedure created two groups (melatonin group and control group) which were very similar. The fitness and PWB score were postoperative significantly enhanced in the melatonin group as compared to the control group (p = 0.005 and p = 0.003). Additionally, histological analysis revealed that acinar necrosis, fat tissue necrosis, and edema were significantly reduced in the melatonin group as compared to the non-melatonin group (p = 0.025, p = 0.003, and p = 0.028).

Conclusions

Pigs, which were treated with melatonin, were characterized by higher fitness and PWB scores than those of the control group. Moreover, melatonin treatment reduces the acinar necrosis, fat tissue necrosis, and edema of pancreatic tissue. Thus, melatonin might be a useful therapeutic option in severe acute pancreatitis.

Diplomats' Mystery Illness and Pulsed Radiofrequency/Microwave Radiation

Importance: A mystery illness striking U.S. and Canadian diplomats to Cuba (and now China) "has confounded the FBI, the State Department and US intelligence agencies" (Lederman, Weissenstein, & Lee, 2017). Sonic explanations for the so-called health attacks have long dominated media reports, propelled by peculiar sounds heard and auditory symptoms experienced. Sonic mediation was justly rejected by experts. We assessed whether pulsed radiofrequency/microwave radiation (RF/MW) exposure can accommodate reported facts in diplomats, including unusual ones. Observations: (1) Noises: Many diplomats heard chirping, ringing or grinding noises at night during episodes reportedly triggering health problems. Some reported that noises were localized with laser-like precision or said the sounds seemed to follow them (within the territory in which they were perceived). Pulsed RF/MW engenders just these apparent "sounds" via the Frey effect. Perceived "sounds" differ by head dimensions and pulse characteristics and can be perceived as located behind in or above the head. Ability to hear the "sounds" depends on high-frequency hearing and low ambient noise. (2) Signs/symptoms: Hearing loss and tinnitus are prominent in affected diplomats and in RF/MW-affected individuals. Each of the protean symptoms that diplomats report also affect persons reporting symptoms from RF/MW: sleep problems, headaches, and cognitive problems dominate in both groups. Sensations of pressure or vibration figure in each. Both encompass vision, balance, and speech problems and nosebleeds. Brain injury and brain swelling are reported in both. (3) Mechanisms: Oxidative stress provides a documented mechanism of RF/MW injury compatible with reported signs and symptoms; sequelae of endothelial dysfunction (yielding blood flow compromise), membrane damage, blood-brain barrier disruption, mitochondrial injury, apoptosis, and autoimmune triggering afford downstream mechanisms, of varying persistence, that merit investigation. (4) Of note, microwaving of the U.S. embassy in Moscow is historically documented. Conclusions and relevance: Reported facts appear consistent with pulsed RF/MW as the source of injury in affected diplomats. Nondiplomats citing symptoms from RF/MW, often with an inciting pulsed-RF/MW exposure, report compatible health conditions. Under the RF/MW hypothesis, lessons learned for diplomats and for RF/MW-affected civilians may each aid the other.

Melatonin inhibits endoplasmic reticulum stress-associated TXNIP/NLRP3 inflammasome activation in lipopolysaccharide-induced endometritis in mice

Endometritis, an inflammatory response of the uterus tissue, is characterized by the production of inflammatory cytokines and migration of neutrophil (PMN) into the uterus tissue. Melatonin has been demonstrated to have anti-inflammatory and antioxidant effects. The purpose of this study was to investigate the protective effects of melatonin on lipopolysaccharide (LPS)-induced endometritis in mice. An endometritis model was induced by LPS and melatonin was given 1 h before LPS treatment. The results showed that melatonin inhibited LPS-induced pathologic changes, Myeloperoxidase (MPO) activity, and levels of interleukin-1 beta (IL-1β). Melatonin also inhibited LPS-induced thioredoxin-interacting protein (TXNIP)/NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome and nuclear factor kappa B (NF-κB) activation, reactive oxygen species (ROS) production, and endoplasmic reticulum (ER) stress. Furthermore, melatonin was found to increase AMPK activity. In conclusion, our results demonstrated that melatonin inhibited ER stress-associated TXNIP/NLRP3 inflammasome activation with a regulation of adenosine monophosphate activated protein kinase (AMPK) in LPS-induced endometritis. Melatonin may serve as a promising nutritional supplement for the treatment of endometritis.

Strategies to decrease oxidative stress biomarker levels in human medical conditions: A meta-analysis on 8-iso-prostaglandin F2α

The widespread detection of elevated oxidative stress levels in many medical conditions has led to numerous efforts to design interventions to reduce its effects. Efforts have been wide-ranging, from dietary changes to administration of antioxidants, supplements, e.g., omega-3-fatty acids, and many medications. However, there is still no systemic assessment of the efficacy of treatments for oxidative stress reduction across a variety of medical conditions. The goal of this meta-analysis is, by combining multiple studies, to quantitate the change in the levels of the popular oxidative stress biomarker 8-iso-prostaglandin F2α (8-iso-PGF2α) after a variety of treatment strategies in human populations. Nearly 350 unique publications with 180 distinct strategies were included in the analysis. For each strategy, the difference between pre- or placebo and post-treatment levels calculated using Hedges' g value of effect. In general, administration of antibiotics, antihyperlipidemic agents, or changes in lifestyle (g = - 0.63, - 0.54, and 0.56) had the largest effect. Administration of supplements, antioxidants, or changes in diet (g = - 0.09, - 0.28, - 0.12) had small quantitative effects. To fully interpret the effectiveness of these treatments, comparisons to the increase in g value for each medical condition is required. For example, antioxidants in populations with coronary artery disease (CAD) reduce the 8-iso-PGF2α levels by g = - 0.34 ± 0.1, which is quantitatively considered a small effect. However, CAD populations, in comparison to healthy populations, have an increase in 8-iso-PGF2α levels by g = 0.38 ± 0.04; therefore, the overall reduction of 8-iso-PGF2α levels is ≈ 90% by this treatment in this specific medical condition. In conclusion, 8-iso-PGF2α levels can be reduced not only by antioxidants but by many other strategies. Not all strategies are equally effective at reducing 8-iso-PGF2α levels. In addition, the effectiveness of any strategy can be assessed only in relation to the medical condition investigated.

Idiopathic pulmonary fibrosis (IPF) signaling pathways and protective roles of melatonin

Idiopathic pulmonary fibrosis (IPF) is characterized by the progressive loss of lung function due to tissue scarring. A variety of pro-inflammatory and pro-fibrogenic factors including interleukin‑17A, transforming growth factor β, Wnt/β‑catenin, vascular endothelial growth factor, platelet-derived growth factor, fibroblast growth factors, endotelin‑1, renin angiotensin system and impaired caveolin‑1 function are involved in the IPF pathogenesis. Current therapies for IPF have some limitations and this highlights the need for effective therapeutic agents to treat this fatal disease. Melatonin and its metabolites are broad-spectrum antioxidants that not only remove reactive oxygen and nitrogen species by radical scavenging but also up-regulate the expression and activity of endogenous antioxidants. Via these actions, melatonin and its metabolites modulate a variety of molecular pathways in different pathophysiological conditions. Herein, we review the signaling pathways involved in the pathophysiology of IPF and the potentially protective effects of melatonin on these pathways.

The benefit of a supplement with the antioxidant melatonin on redox status and muscle damage in resistance-trained athletes

Previous data showed that the administration of high doses of melatonin improved the circadian system in athletes. Here, we investigated in the same experimental paradigm whether the antioxidant properties of melatonin has also beneficial effects against exercise-induced oxidative stress and muscle damage in athletes. Twenty-four athletes were treated with 100 mg·day−1 of melatonin or placebo 30 min before bedtime during 4 weeks in a randomized double-blind scheme. Exercise intensity was higher during the study that before starting it. Blood samples were collected before and after treatment, and plasma was used for oxygen radical absorption capacity (ORAC), lipid peroxidation (LPO), nitrite plus nitrate (NOx), and advanced oxidation protein products (AOPP) determinations. Glutathione (GSH), glutathione disulphide (GSSG) levels, and glutathione peroxidase (GPx) and reductase (GRd) activities, were measured in erythrocytes. Melatonin intake increased ORAC, reduced LPO and NOx levels, and prevented the increase of AOPP, compared to placebo group. Melatonin was also more efficient than placebo in reducing GSSG·GSH−1 and GPx·GRd−1 ratios. Melatonin, but not placebo, reduced creatine kinase, lactate dehydrogenase, creatinine, and total cholesterol levels. Overall, the data reflect a beneficial effect of melatonin treatment in resistance-training athletes, preventing extra- and intracellular oxidative stress induced by exercise, and yielding further skeletal muscle protection against exercise-induced oxidative damage.

Effects of Melatonin and Its Analogues on Pancreatic Inflammation, Enzyme Secretion, and Tumorigenesis

Melatonin is an indoleamine produced from the amino acid l-tryptophan, whereas metabolites of melatonin are known as kynuramines. One of the best-known kynuramines is N¹-acetyl-N¹-formyl-5-methoxykynuramine (AFMK). Melatonin has attracted scientific attention as a potent antioxidant and protector of tissue against oxidative stress. l-Tryptophan and kynuramines share common beneficial features with melatonin. Melatonin was originally discovered as a pineal product, has been detected in the gastrointestinal tract, and its receptors have been identified in the pancreas. The role of melatonin in the pancreatic gland is not explained, however several arguments support the opinion that melatonin is probably implicated in the physiology and pathophysiology of the pancreas. (1) Melatonin stimulates pancreatic enzyme secretion through the activation of entero-pancreatic reflex and cholecystokinin (CCK) release. l-Tryptophan and AFMK are less effective than melatonin in the stimulation of pancreatic exocrine function; (2) Melatonin is a successful pancreatic protector, which prevents the pancreas from developing of acute pancreatitis and reduces pancreatic damage. This effect is related to its direct and indirect antioxidant action, to the strengthening of immune defense, and to the modulation of apoptosis. Like melatonin, its precursor and AFMK are able to mimic its protective effect, and it is commonly accepted that all these substances create an antioxidant cascade to intensify the pancreatic protection and acinar cells viability; (3) In pancreatic cancer cells, melatonin and AFMK activated a signal transduction pathway for apoptosis and stimulated heat shock proteins. The role of melatonin and AFMK in pancreatic tumorigenesis remains to be elucidated.

EFFECTS OF DIURNAL AND NOCTURNAL STRENUOUS EXERCISE ON SERUM MELATONIN LEVELS

ABSTRACT Introduction: There are reports of a possible relationship between melatonin, a hormone secreted by the pineal gland, and exercise. Objective: The present study aims to investigate how diurnal and nocturnal strenuous exercise affects melatonin levels. Methods: The study enrolled 10 healthy sedentary males who did not actively exercise. The subjects had a mean age of 22.20±0.24 years, a mean height of 174.60±2.33 cm, and a mean weight of 69.70±2.42 kg. Two blood samples were collected from the subjects, one at rest, at 10:00 am, and the other immediately after strenuous exercise. Likewise, blood samples were taken from the same group of subjects after 48 hours: at 24:00 hours at rest and immediately after strenuous exercise. Samples were analyzed using the ELISA method to determine the serum melatonin levels (pg/ml). Results: By comparing the values at rest and after exercise, it was found that serum melatonin values remained unchanged with exercise. Serum melatonin values at rest or post-exercise measured at night were higher when compared with those measured during the day (p<0.05). Conclusions: Higher levels of melatonin found in the study appear to result from the increased release of melatonin at night, and not from exercise. The results of this study indicate that strenuous exercise carried out day or night, did not significantly influence serum melatonin levels.

Melatonin as a Potential Agent in the Treatment of Sarcopenia

Considering the increased speed at which the world population is aging, sarcopenia could become an epidemic in this century. This condition currently has no means of prevention or treatment. Melatonin is a highly effective and ubiquitously acting antioxidant and free radical scavenger that is normally produced in all organisms. This molecule has been implicated in a huge number of biological processes, from anticonvulsant properties in children to protective effects on the lung in chronic obstructive pulmonary disease. In this review, we summarize the data which suggest that melatonin may be beneficial in attenuating, reducing or preventing each of the symptoms that characterize sarcopenia. The findings are not limited to sarcopenia, but also apply to osteoporosis-related sarcopenia and to age-related neuromuscular junction dysfunction. Since melatonin has a high safety profile and is drastically reduced in advanced age, its potential utility in the treatment of sarcopenic patients and related dysfunctions should be considered.

Potential pleiotropic beneficial effects of adjuvant melatonergic treatment in posttraumatic stress disorder

Loss of circadian rhythmicity fundamentally affects the neuroendocrine, immune, and autonomic system, similar to chronic stress and may play a central role in the development of stress-related disorders. Recent articles have focused on the role of sleep and circadian disruption in the pathophysiology of posttraumatic stress disorder (PTSD), suggesting that chronodisruption plays a causal role in PTSD development. Direct and indirect human and animal PTSD research suggests circadian system-linked neuroendocrine, immune, metabolic and autonomic dysregulation, linking circadian misalignment to PTSD pathophysiology. Recent experimental findings also support a specific role of the fundamental synchronizing pineal hormone melatonin in mechanisms of sleep, cognition and memory, metabolism, pain, neuroimmunomodulation, stress endocrinology and physiology, circadian gene expression, oxidative stress and epigenetics, all processes affected in PTSD. In the current paper, we review available literature underpinning a potentially beneficiary role of an add-on melatonergic treatment in PTSD pathophysiology and PTSD-related symptoms. The literature is presented as a narrative review, providing an overview on the most important and clinically relevant publications. We conclude that adjuvant melatonergic treatment could provide a potentially promising treatment strategy in the management of PTSD and especially PTSD-related syndromes and comorbidities. Rigorous preclinical and clinical studies are needed to validate this hypothesis.

Melatonin Stimulates the SIRT1/Nrf2 Signaling Pathway Counteracting Lipopolysaccharide (LPS)-Induced Oxidative Stress to Rescue Postnatal Rat Brain

AIMS

Lipopolysaccharide (LPS) induces oxidative stress and neuroinflammation both in vivo and in vitro. Here, we provided the first detailed description of the mechanism of melatonin neuroprotection against LPS-induced oxidative stress, acute neuroinflammation, and neurodegeneration in the hippocampal dentate gyrus (DG) region of the postnatal day 7 (PND7) rat brain.

METHODS

The neuroprotective effects of melatonin against LPS-induced neurotoxicity were analyzed using multiple research techniques, including Western blotting, immunofluorescence, and enzyme-linked immunosorbent assays (ELISAs) in PND7 rat brain homogenates and BV2 cell lysates in vitro. We also used EX527 to inhibit silent information regulator transcript-1 (SIRT1).

RESULTS

A single intraperitoneal (i.p) injection of LPS to PND7 rats significantly induced glial cell activation, acute neuroinflammation, reactive oxygen species (ROS) production and apoptotic neurodegeneration in hippocampal DG region after 4 h. However, the coadministration of melatonin significantly inhibited both LPS-induced acute neuroinflammation and apoptotic neurodegeneration and improved synaptic dysfunction in the hippocampal DG region of PND7 rats. Most importantly, melatonin stimulated the SIRT1/Nrf2 (nuclear factor-erythroid 2-related factor 2) signaling pathway to reduce LPS-induced ROS generation. The beneficial effects of melatonin were further confirmed in LPS-stimulated BV2 microglia cell lines in vitro using EX527 as an inhibitor of SIRT1. LPS-induced oxidative stress, Nrf2 inhibition, and neuroinflammation are SIRT1-dependent in BV2 microglia cell lines.

CONCLUSION

These results demonstrated that melatonin treatment rescued the hippocampal DG region of PND7 rat brains against LPS-induced oxidative stress damage, acute neuroinflammation, and apoptotic neurodegeneration via SIRT1/Nrf2 signaling pathway activation.

Melatonin decreases muscular oxidative stress and inflammation induced by strenuous exercise and stimulates growth factor synthesis

Strenuous exercise is detrimental to athletes because of the overproduction of reactive oxygen species. Melatonin, a classic antioxidant, has been shown to exhibit beneficial effects regarding intense exercise and tissue repair. In this study, we evaluated the onset and resolution of inflammation in melatonin-treated and nontreated rats subjected to a strenuous exercise session. We also analyzed the formation of thiobarbituric acid reactive substances (TBARS) and the activities of catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD). Control and treated rats were subjected to exhaustive exercise after a period of 10 days of melatonin treatment (20 mg/dL). Plasma and muscle levels of tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), interleukin 6 (IL-6), cytokine-induced neutrophil chemoattractant-2-alpha/beta (CINC-2α/β), l-selectin, macrophage inflammatory protein-3-alpha (MIP-3α), and vascular endothelial growth factor (VEGF) were measured prior to, immediately after, and 2 hr after exercise. Our data revealed decreases in the muscle concentrations of IL-1β (35%), TNF-α (13%), IL-6 (48%), and TBARS (40%) in the melatonin-treated group compared with the control group. We also observed decreases in the plasma concentrations of IL-1β (17%) in the melatonin-treated group. VEGF-α concentrations and SOD activity increased by 179% and 22%, respectively, in the melatonin-treated group compared with the control group. We concluded that muscle inflammation and oxidative stress resulting from exhaustive exercise were less severe in the muscles of melatonin-treated animals than in the muscles of control animals. Thus, melatonin treatment may reverse exercise-induced skeletal muscle inflammation and stimulate growth factor synthesis.

A double-blind, placebo-controlled intervention trial of 3 and 10 mg sublingual melatonin for post-concussion syndrome in youths (PLAYGAME): study protocol for a randomized controlled trial

Background

By the age of sixteen, one in five children will sustain a mild traumatic brain injury also known as concussion. Our research found that one in seven school children with mild traumatic brain injury suffer post-concussion syndrome symptoms for three months or longer. Post-concussion syndrome is associated with significant disability in the child and his/her family and yet there are no evidence-based medical treatments available. Melatonin has several potential mechanisms of action that could be useful following mild traumatic brain injury, including neuroprotective effects. The aim of this study is to determine if treatment with melatonin improves post-concussion syndrome in youths following mild traumatic brain injury. Our hypothesis is that treatment of post-concussion syndrome following mild traumatic brain injury with 3 or 10 mg of sublingual melatonin for 28 days will result in a decrease in post-concussion syndrome symptoms compared with placebo.

Methods/Design

Ninety-nine youths with mild traumatic brain injury, aged between 13 and 18 years, who are symptomatic at 30 days post-injury will be recruited. This study will be conducted as a randomized, double blind, placebo-controlled superiority trial of melatonin. Three parallel treatment groups will be examined with a 1:1:1 allocation: sublingual melatonin 3 mg, sublingual melatonin 10 mg, and sublingual placebo. Participants will receive treatment for 28 days. The primary outcome is a change on the Post-Concussion Symptom Inventory (Parent and Youth). The secondary outcomes will include neurobehavioral function, health-related quality of life and sleep. Neurophysiological and structural markers of change, using magnetic resonance imaging techniques and transcranial magnetic stimulation, will also be investigated.

Discussion

Melatonin is a safe and well-tolerated agent that has many biological properties that may be useful following a traumatic brain injury. This study will determine whether it is a useful treatment for children with post-concussion syndrome. Recruitment commenced on 4 December 2014.

Trial registration

This trial was registered on 6 June 2013 at ClinicalTrials.gov. Registration number: NCT01874847.

Melatonin regulates mesenchymal stem cell differentiation: a review

Among the numerous functions of melatonin, the control of survival and differentiation of mesenchymal stem cells (MSCs) has been recently proposed. MSCs are a heterogeneous population of multipotent elements resident in tissues such as bone marrow, muscle, and adipose tissue, which are primarily involved in developmental and regeneration processes, gaining thus increasing interest for tissue repair and restoration therapeutic protocols. Receptor-dependent and receptor-independent responses to melatonin are suggested to occur in these cells. These involve antioxidant or redox-dependent functions of this indolamine as well as secondary effects resulting from autocrine and paracrine responses. Inflammatory cytokines and adipokines, proangiogenic/mitogenic stimuli, and other mediators that influence the differentiation processes may affect the survival and functional integrity of these mesenchymal precursor cells. In this scenario, melatonin seems to regulate signaling pathways that drive commitment and differentiation of MSC into osteogenic, chondrogenic, adipogenic, or myogenic lineages. Common pathways suggested to be involved as master regulators of these processes are the Wnt/β-catenin pathway, the MAPKs and the, TGF-β signaling. In this respect melatonin emerges a novel and potential modulator of MSC lineage commitment and adipogenic differentiation. These and other aspects of the physiological and pharmacological effects of melatonin as regulator of MSC are discussed in this review.

Protective effects of melatonin in reducing oxidative stress and in preserving the fluidity of biological membranes: a review

Free radicals generated within subcellular compartments damage macromolecules which lead to severe structural changes and functional alterations of cellular organelles. A manifestation of free radical injury to biological membranes is the process of lipid peroxidation, an autooxidative chain reaction in which polyunsaturated fatty acids in the membrane are the substrate. There is considerable evidence that damage to polyunsaturated fatty acids tends to reduce membrane fluidity. However, adequate levels of fluidity are essential for the proper functioning of biological membranes. Thus, there is considerable interest in antioxidant molecules which are able to stabilize membranes because of their protective effects against lipid peroxidation. Melatonin is an indoleamine that modulates a wide variety of endocrine, neural and immune functions. Over the last two decades, intensive research has proven this molecule, as well as its metabolites, to possess substantial antioxidant activity. In addition to their ability to scavenge several reactive oxygen and nitrogen species, melatonin increases the activity of the glutathione redox enzymes, that is, glutathione peroxidase and reductase, as well as other antioxidant enzymes. These beneficial effects of melatonin are more significant because of its small molecular size and its amphipathic behaviour, which facilitates ease of melatonin penetration into every subcellular compartment. In the present work, we review the current information related to the beneficial effects of melatonin in maintaining the fluidity of biological membranes against free radical attack, and further, we discuss its implications for ageing and disease.