The effect of melatonin supplementation on lipid profile and anthropometric indices: A systematic review and meta-analysis of clinical trials

Effect of melatonin supplementation on cardiometabolic risk factors, oxidative stress and hormonal profile in PCOS patients: a systematic review and meta-analysis of randomized clinical trials

BACKGROUND

To investigate whether melatonin supplementation can enhance cardiometabolic risk factors, reduce oxidative stress, and improve hormonal and pregnancy-related factors in patients with PCOS.

METHODS

We conducted a systematic search of PubMed/Medline, Scopus, and the Cochrane Library for articles published in English from inception to March 2023. We included randomized controlled trials (RCTs) on the use of melatonin for patients with polycystic ovary syndrome (PCOS). We performed a meta-analysis using a random-effects model and calculated the standardized mean differences (SMDs) and 95% confidence intervals (CIs).

RESULTS

Six studies met the inclusion criteria. The result of meta-analysis indicated that melatonin intake significantly increase TAC levels (SMD: 0.87, 95% CI: 0.46, 1.28, I2 = 00.00%) and has no effect on FBS, insulin, HOMA-IR, TC, TG, HDL, LDL, MDA, hs-CRP, mFG, SHBG, total testosterone, and pregnancy rate in patients with PCOS compare to controls. The included trials did not report any adverse events.

CONCLUSION

Melatonin is a potential antioxidant that may prevent damage from oxidative stress in patients with PCOS. However, the clear effect of melatonin supplementation on cardiometabolic risk factors, hormonal outcomes, and pregnancy-related outcomes needs to be evaluated further in large populations and long-term RCTs.

Overlapping action of melatonin and female reproductive hormones-Understand the impact in pregnancy and menopause

Melatonin is an indolamine secreted to circulation by the pineal gland according to a circadian rhythm. Melatonin levels are higher during nighttime, and the principal function of this hormone is to organize the temporal night and day distribution of physiological adaptive processes. Besides hormonal pineal production, melatonin is synthesized in various organs and tissues like the ovaries or the placenta for local utilization. In addition to its function as a circadian messenger, melatonin is also associated with many physiological functions. For example, melatonin has antioxidant properties and is involved in the regulation of energy and bone metabolism, and reproduction. Melatonin impacts several stages of reproduction and the action across the hypothalamus-pituitary-gonadal axis is well described. However, it is not well understood how those actions impact the female reproductive hormones secretion nor the consequent physiological outcomes. Thus, the first part of this chapter describes the regulation of female reproductive hormone synthesis by melatonin. Moreover, melatonin and female reproductive hormones have coincident physiological functions. Life stages like pregnancy or menopause are characterized by alterations in the reproductive hormones secretion that may be associated with certain physiological stages. Therefore, the second part discusses whether melatonin fluctuations could have an overlapping role with reproductive hormones in contributing to clinical outcomes associated with pregnancy and menopause.

Moringa oleifera Lam. as a potential plant for alleviation of the metabolic syndrome-A narrative review based on in vivo and clinical studies

The metabolic syndrome (MetS) refers to the co-occurrence of risk factors, including hyperglycaemia, increased body weight, hypertension and dyslipidemia, which eventually lead to diabetes and cardiovascular disease, a common health problem worldwide. Recently, there has been an increasing interest in the use of plant-based products for the management of MetS, because of their less detrimental and more beneficial effects. Moringa oleifera (Moringaceae), commonly known as drumstick, is cultivated worldwide for its nutritional and medicinal properties. This review focuses on the in vivo and human studies concerning the potential of M. oleifera in the alleviation of MetS and its comorbidities. The search for relevant articles was carried out in PubMed and Google Scholar databases. Randomised controlled and clinical trials from the PubMed database were included in this review. The results suggested that the administration of M. oleifera, in vivo, shows clear signs of improvement in MetS indices. Despite fewer human studies, the existing data documented convincing results that uphold the potential of M. oleifera against MetS. Therefore, future research discussing the probable mechanism of action is much needed which could further assure the usage of M. oleifera in the treatment regimen of MetS.

Evaluating the Relationship between Circadian Rhythms and Sleep, Metabolic and Cardiovascular Disorders: Current Clinical Evidence in Human Studies

Circadian rhythms are generated by the circadian clock, a self-sustained internal timing system that exhibits 24-h rhythms in the body. Many metabolic, cellular, behavioral and physiological processes are regulated by the circadian clock in coordination with environmental cues. The present study is a comprehensive review of the currently existing evidence concerning the relationship between circadian rhythms and sleep, metabolic, and cardiovascular disorders. We thoroughly searched the online databases PubMed, Scopus, and Web of Science to find the existing clinical studies from the last twenty-three years (2000-2023). Circadian misalignment was found to be associated with an increase in the risk of metabolic disorders, cardiovascular diseases, and obesity, as well as inadequate sleep quality. In this review article, all the included studies had a strength protocol design and all of them were conducted on humans. However, the most common limitations of them were the small sample size and the short time of the intervention. In conclusion, managing the factors that disrupt the optimal function of central and peripheral clocks can help to reduce the risk of metabolic and cardiovascular diseases, improving also sleep quality. Future studies should further explore the underlying mechanisms of the interconnections between circadian clocks and sleep, metabolic, and cardiovascular disorders. This may provide new opportunities for advance chronotherapy approach.

Protective effects of melatonin against the toxic effects of environmental pollutants and heavy metals on testicular tissue: A systematic review and meta-analysis of animal studies

BACKGROUND

Environmental pollution and infertility are two modern global challenges that agonize personal and public health. The causal relationship between these two deserves scientific efforts to intervene. It is believed that melatonin maintains antioxidant properties and may be utilized to protect the testicular tissue from oxidant effects caused by toxic materials.

METHODS

A systematic literature search was conducted in PubMed, Scopus, and Web of Science to identify the animal trial studies that evaluated melatonin therapy's effects on rodents' testicular tissue against oxidative stress caused by heavy metal and non-heavy metal environmental pollutants. Data were pooled, and standardized mean difference and 95% confidence intervals were estimated using the random-effect model. Also, the risk of bias was assessed using the Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) tool. (PROSPERO: CRD42022369872).

RESULTS

Out of 10039 records, 38 studies were eligible for the review, of which 31 were included in the meta-analysis. Most of them showed beneficial effects of melatonin therapy on testicular tissue histopathology. [20 toxic materials were evaluated in this review, including arsenic, lead, hexavalent chromium, cadmium, potassium dichromate, sodium fluoride, cigarette smoke, formaldehyde, carbon tetrachloride (CCl4), 2-Bromopropane, bisphenol A, thioacetamide, bisphenol S, ochratoxin A, nicotine, diazinon, Bis(2-ethylhexyl) phthalate (DEHP), Chlorpyrifos (CPF), nonylphenol, and acetamiprid.] The pooled results showed that melatonin therapy increased sperm count, motility, viability and body and testicular weights, germinal epithelial height, Johnsen's biopsy score, epididymis weight, seminiferous tubular diameter, serum testosterone, and luteinizing hormone levels, testicular tissue Malondialdehyde, glutathione peroxidase, superoxide dismutase, and glutathione levels. On the other hand, abnormal sperm morphology, apoptotic index, and testicular tissue nitric oxide were lower in the melatonin therapy arms. The included studies presented a high risk of bias in most SYRCLE domains.

CONCLUSION

In conclusion, our study demonstrated amelioration of testicular histopathological characteristics, reproductive hormonal panel, and tissue markers of oxidative stress. Melatonin deserves scientific attention as a potential therapeutic agent for male infertility.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO, identifier CRD42022369872.

Melatonin Potentiates Exercise-Induced Increases in Skeletal Muscle PGC-1α and Optimizes Glycogen Replenishment

Compelling evidence has demonstrated the effect of melatonin on exhaustive exercise tolerance and its modulatory role in muscle energy substrates at the end of exercise. In line with this, PGC-1α and NRF-1 also seem to act on physical exercise tolerance and metabolic recovery after exercise. However, the literature still lacks reports on these proteins after exercise until exhaustion for animals treated with melatonin. Thus, the aim of the current study was to determine the effects of acute melatonin administration on muscle PGC-1α and NRF-1, and its modulatory role in glycogen and triglyceride contents in rats subjected to exhaustive swimming exercise at an intensity corresponding to the anaerobic lactacidemic threshold (iLAn). In a randomized controlled trial design, thirty-nine Wistar rats were allocated into four groups: control (CG = 10), rats treated with melatonin (MG = 9), rats submitted to exercise (EXG = 10), and rats treated with melatonin and submitted to exercise (MEXG = 10). Forty-eight hours after the graded exercise test, the animals received melatonin (10 mg/kg) or vehicles 30 min prior to time to exhaustion test in the iLAn (tlim). Three hours after tlim the animals were euthanized, followed by muscle collection for specific analyses: soleus muscles for immunofluorescence, gluteus maximus, red and white gastrocnemius for the assessment of glycogen and triglyceride contents, and liver for the measurement of glycogen content. Student t-test for independent samples, two-way ANOVA, and Newman keuls post hoc test were used. MEXG swam 120.3% more than animals treated with vehicle (EXG; p < 0.01). PGC-1α and NRF-1 were higher in MEXG with respect to the CG (p < 0.05); however, only PGC-1α was higher for MEXG when compared to EXG. Melatonin reduced the triglyceride content in gluteus maximus, red and white gastrocnemius (F = 6.66, F = 4.51, and F = 6.02, p < 0.05). The glycogen content in red gastrocnemius was higher in MEXG than in CG (p = 0.01), but not in EXG (p > 0.05). In conclusion, melatonin was found to enhance exercise tolerance, potentiate exercise-mediated increases in PGC-1α, decrease muscle triglyceride content and increase muscle glycogen 3 h after exhaustive exercise, rapidly providing a better cellular metabolic environment for future efforts.

Controlled-release oral melatonin supplementation for hypertension and nocturnal hypertension: A systematic review and meta-analysis

Oral melatonin is a potential alternative treatment for hypertension and nocturnal hypertension. However, high‐quality and relevant meta‐analyses are lacking. This meta‐analysis aimed to investigate whether oral melatonin supplementation reduces daytime/asleep blood pressure and cardiovascular risk, improves sleep quality, and is well‐tolerated compared with placebo. Relevant articles were searched in multiple databases, including MEDLINE, EMBASE, CINAHL Complete, and the Cochrane Library, from their inception to June 2021. The included studies were randomized controlled trials recruiting patients with hypertension, using oral melatonin as the sole intervention, and investigating its effect on blood pressure. The mean out‐of‐office (including 24‐h, daytime, and asleep) systolic and diastolic blood pressures, sleep quality, and side effects were compared between the melatonin and placebo arms using pairwise random‐effect meta‐analyses. A risk of bias assessment was performed using the Cochrane risk‐of‐bias tool. Four studies were included in the analysis and only one study was considered to have a low risk of bias. No study reported on cardiovascular risk or outcomes. Only controlled‐release melatonin (not an immediate‐release preparation) reduced asleep systolic blood pressure by 3.57 mm Hg (95% confidence interval: –7.88 to .73; I² = 0%). It also reduced asleep and awake diastolic blood pressure, but these differences were not statistically significant. Melatonin improves sleep efficacy and total sleep time and is safe and well‐tolerated. Due to the limited number of high‐quality trials, the quality of evidence was low to very low. Therefore, adequately powered randomized controlled trials on melatonin are warranted.

Melatonin supplementation improves N-terminal pro-B-type natriuretic peptide levels and quality of life in patients with heart failure with reduced ejection fraction: Results from MeHR trial, a randomized clinical trial

Background

Melatonin, the major secretion of the pineal gland, has beneficial effects on the cardiovascular system and might advantage heart failure with reduced ejection fraction (HFrEF) by attenuating the effects of the renin–angiotensin–aldosterone and sympathetic system on the heart besides its antioxidant and anti‐inflammatory effects.

Hypothesis

We hypothesized that oral melatonin might improve echocardiographic parameters, serum biomarkers, and a composite clinical outcome (including quality of life, hospitalization, and mortality) in patients with HFrEF.

Methods

A placebo‐controlled double‐blinded randomized clinical trial was conducted on patients with stable HFrEF. The intervention was 10 mg melatonin or placebo tablets administered every night for 24 weeks. Echocardiography and measurements of N‐terminal pro‐B‐type natriuretic peptide (NT‐Pro BNP), high‐sensitivity C‐reactive protein, lipid profile, and psychological parameters were done at baseline and after 24 weeks.

Results

Overall, 92 patients were recruited, and 85 completed the study (melatonin: 42, placebo: 43). Serum NT‐Pro BNP decreased significantly in the melatonin compared with the placebo group (estimated marginal means for difference [95% confidence interval]: 111.0 [6.2–215.7], p = .044). Moreover, the melatonin group had a significantly better clinical outcome (0.93 [0.18–1.69], p = .017), quality of life (5.8 [0.9–12.5], p = .037), and New York Heart Association class (odds ratio: 12.9 [1.6–102.4]; p = .015) at the end of the trial. Other studied outcomes were not significantly different between groups.

Conclusions

Oral melatonin decreased NT‐Pro BNP and improved the quality of life in patients with HFrEF. Thus it might be a beneficial supplement in HFrEF.

Mechanisms of Melatonin in Obesity: A Review

Obesity and its complications have become a prominent global public health problem that severely threatens human health. Melatonin, originally known as an effective antioxidant, is an endogenous hormone found throughout the body that serves various physiological functions. In recent decades, increasing attention has been paid to its unique function in regulating energy metabolism, especially in glucose and lipid metabolism. Accumulating evidence has established the relationship between melatonin and obesity; nevertheless, not all preclinical and clinical evidence indicates the anti-obesity effect of melatonin, which makes it remain to conclude the clinical effect of melatonin in the fight against obesity. In this review, we have summarized the current knowledge of melatonin in regulating obesity-related symptoms, with emphasis on its underlying mechanisms. The role of melatonin in regulating the lipid profile, adipose tissue, oxidative stress, and inflammation, as well as the interactions of melatonin with the circadian rhythm, gut microbiota, sleep disorder, as well as the α7nAChR, the opioidergic system, and exosomes, make melatonin a promising agent to open new avenues in the intervention of obesity.

Low serum lipid levels, use of statin and cerebral microbleeds: A systematic review and meta-analysis

INTRODUCTION

Previous studies have shown that low serum lipids and statins may be related to cerebral hemorrhage. We made the meta-analysis to evaluate the associations between serum lipid levels or statins treatment and cerebral microbleeds (CMBs) to identify whether the similar correlation also existed.

METHOD

We comprehensively searched the Medline, Embase, Cochrane library, Web of Science, only included English journal articles, and systematically collected the observational studies and randomized controlled trials (RCTs) from September 1975 to August 2021. Random-effects model was used to pool data. Statistical heterogeneity was assessed by I² statistic and chi-square. 11 items checklists recommended by the Agency for Healthcare Research and Quality (AHRQ), Newcastle-Ottawa Scale (NOS), and Cochrane Risk of Bias tool (ROB) were used to evaluate the methodological quality of cross-sectional studies, cohort studies and randomized controlled trial, respectively.

RESULTS

Five cohort studies, two RCTs, and ten cross-sectional studies, including 16,637 subjects and 2663 CMBs patients, were included in our quantitative synthesis. Our study found that after adjusting the covariates, total cholesterol (TC) was significantly inversely correlated with the prevalent CMBs in any location, while total triglycerides (TG) and High-density lipoprotein (HDL) were significantly inversely associated with prevalent deep CMBs. Low-density lipoprotein (LDL) was negatively associated with incident CMBs after adjusted confounders. We did not found statistical differences between statin and CMBs after adjusted covariates.

CONCLUSION

Serum major lipid (TC TG HDL LDL) levels may be inversely associated with CMBs. Currently, no sufficient evidence proves that statin therapy is the risk factor of CMBs.

Associations Between Dietary Melatonin Intake and Total and Cause-Specific Mortality Among Japanese Adults in the Takayama Study

Potential health benefits of melatonin have been suggested. Although melatonin is present in various foods, little is known about the health effects of dietary melatonin intake. We estimated habitual dietary melatonin intake and examined its association with total and cause-specific mortality in a population-based cohort study in Japan. Study subjects included 13,355 men and 15,724 women aged ≥35 years who responded to a self-administered questionnaire in 1992. Their diets were assessed via a food frequency questionnaire at baseline. The melatonin content in various foods on the questionnaire was measured to estimate melatonin intake. Mortality was ascertained during 16 years of follow-up (1992-2008). Hazard ratios (HRs) and 95% confidence intervals (CIs) for total and cause-specific mortality were calculated according to melatonin quartiles. A total of 5,339 deaths occurred during follow-up. Melatonin intake was significantly associated with decreased risks of total mortality, cardiovascular mortality, and noncancer, noncardiovascular mortality after controlling for covariates; HRs for the highest quartile of melatonin intake versus the lowest were 0.90 (95% CI: 0.82, 0.98; P for trend = 0.05), 0.85 (95% CI: 0.72, 0.99; P for trend = 0.10), and 0.77 (95% CI: 0.67, 0.90; P for trend = 0.003), respectively. The data suggest a potential benefit of dietary melatonin with regard to mortality rates.

Melatonin supplementation and anthropometric indicators of obesity: A systematic review and meta-analysis

OBJECTIVE

According to in vivo and in vitro studies, melatonin appears to be a potential supplement for obesity reduction. The aim of this study was to review the literature on randomized clinical trials that evaluated the effects of melatonin supplementation on anthropometric indicators of obesity in humans.

METHODS

We conducted a systematic review with meta-analysis in the following databases: Pubmed, LILACS, Scielo, Scopus, Web of Science, Cochrane, and Embase. We included studies that evaluated melatonin supplementation's effects, compared with placebo, on anthropometric measures, including body weight, body mass index (BMI), and waist circumference, in people ≥18 y of age. This systematic review and meta-analysis were registered on PROSPERO: CRD42021241079.

RESULTS

Of the 23 studies included, 11 showed significant results from melatonin supplementation on weight loss, BMI, or waist circumference, compared with placebo. In the meta-analysis, melatonin supplementation significantly reduced body weight (standardized mean difference, -0.48; 95% confidence interval, -0.94 to -0.02; P = <0.01; I² = 92%). Results for BMI and waist circumference were null. The I² tests were significant for the analyses with significant results.

CONCLUSION

The results demonstrated that melatonin supplementation was responsible for significantly reducing body weight. More studies are needed before melatonin can be recommended for weight loss.

The effect of garlic (Allium sativum) supplementation on the lipid parameters and blood pressure levels in women with polycystic ovary syndrome: A randomized controlled trial

Polycystic ovary syndrome (PCOS) is the most prevalent female endocrine-related disorder in reproductive ages. The aim of the study was to investigate the effect of garlic on the lipid parameters and blood pressure levels in women with PCOS. The present study was a randomized, double-blinded control trial, conducted on 80 PCOS patients. Participants were taught to intake either a total 800 mg/day garlic supplement or an identical placebo (starch) after lunch for 8 weeks. Physical activity, diet intake, anthropometric measures, and blood pressure were evaluated at baseline and end of the study. The blood sample was also taken to assess the change in outcomes of interest at the pre- and post-intervention. Garlic supplementation significantly reduced serum total cholesterol (change mean difference: -8.05, 95% CI: -15.47, -0.62) and LDL-C (change mean difference: -7.67, 95%CI: -14.64, -0.70) levels in comparison to the control group. In addition, a trend to a significant decrease was found in serum triglyceride levels and Systolic blood pressure; however, no significant difference was observed between two groups in HDL-C and diastolic blood pressure levels. The present study suggested that garlic supplementation might be effective on lipid markers improvement. Further studies are needed to confirm our findings.

Exogenous melatonin decreases circadian misalignment and body weight among early types

Shift workers experience chronic circadian misalignment, which can manifest itself in reduced melatonin production, and has been associated with metabolic disorders. In addition, chronotype modulates the effect of night shift work, with early types presenting greater circadian misalignment when working night shift as compared to late types. Melatonin supplementation has shown positive results reducing weight gain in animal models, but the effect of exogenous melatonin in humans on body weight in the context of shift work remains inconsistent. The aim of this study was thus to evaluate the effects of exogenous melatonin on circadian misalignment and body weight among overweight night shift workers, according to chronotype, under real-life conditions. We conducted a double-blind, randomized, placebo-controlled, crossover trial where melatonin (3 mg) or placebo was administered on non-night shift nights for 12 weeks in 27 female nurses (37.1 yo, ±5.9 yo; BMI 29.9 kg/m2 , ±3.3 kg/m2 ). Melatonin (or placebo) was only taken on nights when the participants did not work night shifts, that is, on nights when they slept (between night shifts and on days off). Composite Phase Deviations (CPD) of actigraphy-based mid-sleep timing were calculated to measure circadian misalignment. The analyses were performed for the whole group and by chronotype. We found approximately 20% reduction in circadian misalignment after exogenous melatonin administration considering all chronotypes. Moreover, melatonin supplementation in those who presented high circadian misalignment, as observed in early chronotypes, reduced body weight, BMI, waist circumference, and hip circumference, without any change in the participants' calorie intake or physical activity levels.

Exogenous application of melatonin to plants, algae, and harvested products to sustain agricultural productivity and enhance nutritional and nutraceutical value: A meta-analysis

Melatonin is produced by plants, algae, and animals. Worldwide studies show diverse positive effects of exogenous melatonin on plants, edible plant products, and algae, but the potential of melatonin to enhance food and feed systems through these positive effects remains largely unexplored. Through a meta-analysis of about 25,000 observations, we show for the first time that exogenous application of melatonin significantly increases crop productivity and yields, and enhances the nutritional and nutraceutical value of edible plant products and algae by regulating diverse biological functions. We demonstrate that melatonin can improve plants, edible plant products, and algae under various current climate change scenarios, environmental pollution factors, and other stresses by about 7% to nearly 30%, on average, depending on the stressor. We also analyze various technical/methodological factors influencing the desired outcomes and identify conditions that offer optimal enhancement. We show that the positive effect of melatonin on plants and edible plant products varies among species, genera, and families, and strongly depends on the concentration of melatonin and treatment duration. The effect of melatonin is slightly lower on the monocot clade Commelinids than on the eudicot clades Asterids and Rosids. We also show that its stimulatory effect on plants depends on cultivation system, with a larger effect obtained in hydroponic systems. However, it does not depend on application stage (seed or vegetative), application route (foliage, roots, or seed), and whether the cultivation system is ex vivo or in vivo. This is the first meta-analysis examining the effects of melatonin on plants, edible plant products, and algae, and offers a scientific and technical roadmap facilitating sustainable food and feed production through the application of exogenous melatonin.

Melatonin as a powerful antioxidant

Melatonin is a hormone that has many body functions and, for several decades, its antioxidant potential has been increasingly talked about. There is a relationship between failure in melatonin production in the pineal gland, an insufficient supply of this hormone to the body, and the occurrence of free radical etiology diseases such as neurodegenerative diseases, cardiovascular diseases, diabetes, cancer and others. Despite the development of molecular biology, numerous in vitro and in vivo studies, the exact mechanism of melatonin antioxidant activity is still unknown. Nowadays, the use of melatonin supplementation is more and more common, not only to prevent insomnia, but also to slow down the aging process and provide protection against diseases. The aim of this study is to get acquainted with current reports on melatonin, antioxidative mechanisms and their importance in diseases of free radical etiology.

Melatonin Supplementation and Anthropometric Indices: A Randomized Double-Blind Controlled Clinical Trial

Obesity, as the most common metabolic disorder in the world, is characterized by excess body fat. This study is aimed at determining the effects of melatonin supplementation on body weight, nody mass index (BMI), waist circumference (WC), and body fat mass percentage (BFMP) in people with overweight or obesity. Thirty eight overweight or class-I obese adult individuals were recruited in the study (8 men and 30 women). Participants prescribed a weight-loss diet and then randomly were allocated to melatonin or placebo groups. Participants received either a 3-milligram melatonin or placebo tablet per day for 12 weeks. In order to assess differences at the significance level of 0.05, repeated measure ANOVA and paired t-test were used. According to the results, a significant reduction was found in participants' body weight, WC, and BMI in both groups (p = 0.001). However, for the last six weeks, significant reductions of these parameters were observed only in the melatonin group (p = 0.01). The BFMP of participants in the melatonin group showed a significant reduction at the end of the study compared to the initial measurements (p = 0.008). Nevertheless, the results of the present study alone are not sufficient to conclude on the effects of melatonin consumption on anthropometric indices, and it seems that further studies are required in this regard.

Ameliorating effect of melatonin against nicotine induced lung and heart toxicity in rats

The present study was carried out to investigate the ameliorative effects of melatonin against nicotine-induced heart and lung toxicity. For this purpose, 75 mature male Sprague Dawley (SD) rats weighing 150-170 g were randomly divided into five groups (15 rats each): control group (rats were I/P injected with 1% ethanol in saline), nicotine group (rats were I/P injected with 0.6 mg/kg body weight), and combined nicotine and melatonin groups (rats received nicotine as in the previous group and melatonin at a dose of 1, 5, or 10 mg/kg body weight, respectively); all treatments were continued for 21 days. Fasting blood samples were collected from each rat at the 11th day and one day after the end of the last injection (22nd day) for complete blood count (CBC) determination, while sera were collected for the determination of lipid profiles. Malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, and reduced glutathione (GSH) as well as DNA fragmentation percentage were assessed in cardiac tissue. Heart and lung samples were collected for estimation of caspase-3 expression and histopathological examination. The results revealed that nicotine increased the number of RBCs, Hb concentration, total cholesterol, and low density lipoprotein (LDL) and decreased high density lipoprotein (HDL). In addition, it decreased SOD activity and GSH concentration with increased MDA concentration, and DNA fragmentation in the heart, as well as caspase-3 expression in both heart and lungs. It also induced histopathological changes in the heart and lung tissues. Melatonin could ameliorate the deleterious effect of nicotine on the previous parameters either partially or completely, where melatonin restored complete blood count, improved lipid profile, mended lipid peroxidation and antioxidant parameters in the cardiac tissue, rectified caspase-3 expression in the heart and lungs, ameliorated DNA fragmentation percentage in the heart, and protected both heart and lung tissue against the harmful effect of nicotine. It is concluded that melatonin has a protective effect on the heart and lungs against the harmful effect of nicotine.

Sleep and Cardiovascular Risk

Sleep is essential for healthy being and healthy functioning of human body as a whole, as well as each organ and system. Sleep disorders, such as sleep-disordered breathing, insomnia, sleep fragmentation, and sleep deprivation are associated with the deterioration in human body functioning and increased cardiovascular risks. However, owing to the complex regulation and heterogeneous state sleep per se can be associated with cardiovascular dysfunction in susceptible subjects. The understanding of sleep as a multidimensional concept is important for better prevention and treatment of cardiovascular diseases.

Cigarette smoke extract stimulates PCSK9 production in HepG2 cells via ROS/NF‑κB signaling

Cigarette smoke (CS) exposure is a risk factor for dyslipidemia and atherosclerosis. Reduced expression of low-density lipoprotein receptor (LDLR) in hepatocytes may be one of the underlying mechanisms for these disorders. The aim of the present study was to investigate the molecular mechanism underlying the regulatory effect of CS extract (CSE) on proprotein convertase subtilisin/kexin type 9 (PCSK9) and low LDLR expression in HepG2 cells. PCSK9 and LDLR mRNA and protein expression levels in HepG2 cells were evaluated after CSE treatment via reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. In addition, total intracellular reactive oxygen species (ROS) production was determined via 2,7-dichlorofluorescein diacetate fluorescence. CSE significantly increased PCSK9 expression and inhibited LDLR expression in a time- and concentration-dependent manner. Furthermore, CSE significantly induced ROS production and nuclear factor κB (NF-κB) activation. However, pretreatment with a ROS scavenger or an NF-κB inhibitor significantly attenuated the CSE-induced changes in PCSK9 and LDLR expression. In addition, pretreatment with melatonin markedly reduced ROS production, NF-κB activation and PCSK9 expression, and increased LDLR expression in the CSE-treated cells. These data suggest that melatonin inhibits CSE-regulated PCSK9 and LDLR production in HepG2 cells via ROS/NF-κB signaling.

Melatonin and its Relationships with Diabetes and Obesity: A Literature Review

BACKGROUND

Obesity is an important clinical entity, causing many public health issues. Around two billion people in the world are overweight and obese. Almost 40% of American adults are obese and Brazil has about 18 million obese people. Nowadays, 415 million people have diabetes, around 1 in every 11 adults. These numbers will rise to 650 million people within 20 years. Melatonin shows a positive profile on the regulation of the metabolism of the human body.

OBJECTIVE

This study aimed to carry out a broad narrative review of the metabolic profile and associations between melatonin, diabetes and obesity.

METHODS

Article reviews, systematic reviews, prospective studies, retrospective studies, randomized, double-blind, and placebo-controlled trials in humans recently published were selected and analyzed. A total of 368 articles were collated and submitted to the eligibility analysis. Subsequently, 215 studies were selected to compose the content part of the paper, and 153 studies composed the narrative review.

RESULTS

Studies suggest a possible role of melatonin in metabolic diseases such as obesity, T2DM and metabolic syndrome. Intervention studies using this hormone in metabolic diseases are still unclear regarding the possible benefit of it. There is so far no consensus about the possible role of melatonin as an adjuvant in the treatment of metabolic diseases. More studies are necessary to define possible risks and benefits of melatonin as a therapeutic agent.

Melatonin supplementation in the management of obesity and obesity-associated disorders: A review of physiological mechanisms and clinical applications

Despite the evolving advances in clinical approaches to obesity and its inherent comorbidities, the therapeutic challenge persists. Among several pharmacological tools already investigated, recent studies suggest that melatonin supplementation could be an efficient therapeutic approach in the context of obesity. In the present review, we have amalgamated the evidence so far available on physiological effects of melatonin supplementation in obesity therapies, addressing its effects upon neuroendocrine systems, cardiometabolic biomarkers and body composition. Most studies herein appraised employed melatonin supplementation at dosages ranging from 1 to 20 mg/day, and most studies followed up participants for periods from 3 weeks to 12 months. Overall, it was observed that melatonin plays an important role in glycaemic homeostasis, in addition to modulation of white adipose tissue activity and lipid metabolism, and mitochondrial activity. Additionally, melatonin increases brown adipose tissue volume and activity, and its antioxidant and anti-inflammatory properties have also been demonstrated. There appears to be a role for melatonin in adiposity reduction; however, several questions remain unanswered, for example melatonin baseline levels in obesity, and whether any seeming hypomelatonaemia or melatonin irresponsiveness could be clarifying factors. Supplementation dosage studies and more thorough clinical trials are needed to ascertain not only the relevance of such findings but also the efficacy of melatonin supplementation.

Effect of melatonin supplementation on oxidative stress parameters: A systematic review and meta-analysis

BACKGROUND

Oxidative stress, defined as an imbalance between pro-oxidants and neutralizing antioxidants within the body, is a growing public health concern. Oxidative stress is involved in the progression of nearly all chronic diseases. Melatonin has been suggested to reduce oxidative stress by its potential radical scavenging properties.

OBJECTIVE

To determine the efficacy and safety of melatonin as a therapy for the improvement of oxidative stress parameters in randomized controlled trials.

METHODS

A systematic database search using Scopus, PubMed/Medline, EMBASE, Web of Science, the Cochrane Controlled Register of Trials and clinicaltrials.gov (https://clinicaltrials.gov) for studies published up to July 2020 was conducted. We included studies which investigated the effect of supplemental melatonin compared to placebo on oxidative stress parameters in unhealthy patients. Quantitative data synthesis was conducted using a random-effects model with standard mean difference (SMD) and 95 % confidence intervals (CI). Cochrane's Q and I² values were used to evaluate heterogeneity.

RESULTS

A total of 12 randomized controlled trials (RCTs) were eligible. The meta-analysis indicated an association between melatonin intake and a significant increase in total antioxidant capacity (TAC) (SMD: 0.76; 95 % CI: 0.30, 1.21; I² = 80.1 %), glutathione (GSH) levels (SMD: 0.57; 95 % CI: 0.32, 0.83; I² = 15.1 %), superoxide dismutase (SOD) (SMD: 1.38; 95 % CI: 0.13, 2.62; I² = 86.9 %), glutathione peroxidase (GPx) (SMD: 1.36; 95 % CI: 0.46, 2.30; I² = 89.3 %), glutathione reductase (GR) (SMD: 1.21; 95 % CI: 0.65, 1.77; I² = 00.0 %) activities, and a significant reduction in malondialdehyde (MDA) levels (SMD: -0.79; 95 % CI: -1.19, -0.39; I² = 73.1 %). Melatonin intake was not shown to significantly affect nitric oxide (NO) levels (SMD: -0.24; 95 % CI: -0.61, 0.14; I² = 00.0 %) or catalase (CAT) activity (SMD: -1.38; 95 % CI: -1.42, 4.18; I² = 96.6 %).

CONCLUSION

Melatonin intake was shown to have a significant impact on improving Oxidative stress parameters. However, future research through large, well-designed randomized controlled trials are required to determine the effect of melatonin on oxidative stress parameters in different age groups and different disease types.

Cigarette smoke exposure impairs lipid metabolism by decreasing low-density lipoprotein receptor expression in hepatocytes

BACKGROUND

Cigarette smoke (CS) exposure impairs serum lipid profiles and the function of vascular endothelial cells, which accelerates the atherosclerosis. However, the precise mechanism and effect on the expression of low-density lipoprotein receptor (LDLR) in the liver by CS exposure is still unclear.

METHODS

In this study, adult male C57BL/6 J mice were divided into three groups, with one group being exposed to CS for 6 weeks. HepG2 cells were treated with CS extract at concentrations of 1, 2.5, 5, and 10%.

RESULTS

The serum levels of total cholesterol (TC), triglycerides (TGs), and low-density lipoprotein cholesterol (LDL-C) for the CS-exposure group were significantly higher than those in the control group (P < 0.05). Moreover, CS exposure decreased the LDLR expression in the hepatocytes and promoted inflammation in the blood vessel walls. Melatonin was intraperitoneally injected at 10 mg/kg/d for 6 weeks alongside CS exposure, and this significantly decreased the levels of TC, TGs, and LDL-C and decreased the expression of intercellular adhesion molecule-1 and the infiltration of cluster determinant 68-cells. In vitro, CS extract prepared by bubbling CS through phosphate-buffered saline decreased the LDLR expression in HepG2 cells in a time- and concentration-dependent manner, and this effect was prevented by pretreatment with 100 μM melatonin.

CONCLUSIONS

In conclusion, CS exposure impaired lipid metabolism and decreased LDLR expression in hepatocytes, and these effects could be prevented by melatonin supplementation. These findings implied that melatonin has the potential therapeutic applicability in the prevention of lipid metabolic disorder in smokers.

Melatonin Supplementation Attenuates the Pro-Inflammatory Adipokines Expression in Visceral Fat from Obese Mice Induced by A High-Fat Diet

Obesity is defined as a condition of abnormal or excessive fat accumulation in white adipose tissue that results from the exacerbated consumption of calories associated with low energy expenditure. Fat accumulation in both adipose tissue and other organs contributes to a systemic inflammation leading to the development of metabolic disorders such as type 2 diabetes, hypertension, and dyslipidemia. Melatonin is a potent antioxidant and improves inflammatory processes and energy metabolism. Using male mice fed a high-fat diet (HFD-59% fat from lard and soybean oil; 9:1) as an obesity model, we investigated the effects of melatonin supplementation on the prevention of obesity-associated complications through an analysis of plasma biochemical profile, body and fat depots mass, adipocytes size and inflammatory cytokines expression in epididymal (EPI) adipose depot. Melatonin prevented a gain of body weight and fat depot mass as well as adipocyte hypertrophy. Melatonin also reversed the increase of total cholesterol, triglycerides and LDL-cholesterol. In addition, this neurohormone was effective in completely decreasing the inflammatory cytokines leptin and resistin in plasma. In the EPI depot, melatonin reversed the increase of leptin, Il-6, Mcp-1 and Tnf-α triggered by obesity. These data allow us to infer that melatonin presents an anti-obesity effect since it acts to prevent the progression of pro-inflammatory markers in the epididymal adipose tissue together with a reduction in adiposity.