Melatonin as a master regulator of cell death and inflammation: molecular mechanisms and clinical implications for newborn care

Presence of melatonin in foods of daily consumption: The benefit of this hormone for health

Melatonin (MLT) is a hormone that exists in all living organisms, including bacteria, yeast, fungi, animals, and plants, many of which are ingested daily in the diet. However, the exact concentrations of melatonin in each of the foods and the effect on health of the intake of foods rich in MLT are not known. Therefore, the aim of this review was to gather the available information on the melatonin content of different foods and to evaluate the effect that this hormone has on different pathologies. The amount of MLT may vary depending on the variety, origin, heat treatment, processing, and analysis technique, among other factors. Dietary interventions with foods rich in MLT report health benefits, but there is no evidence that hormone is partially responsible for the clinical improvement. Therefore, it is necessary to evaluate the MLT content in more foods, as well as the effect that cooking/processing has on the amount of MLT, to estimate its total intake in a typical diet and better explore its potential impact on the health.

Beneficial effects of melatonin on boar sperm motility and kinematics are mediated by MT1 receptor

Melatonin, a hormone synthesized in various tissues, plays a crucial role in modulating sperm characteristics, yet its protective function on boar sperm remains poorly understood. This study aimed to investigate the expression and localization of melatonin-related proteins (AANAT, ASMT, MT1, MT2, and NQO2) in pig tissues, assess the impact of melatonin on pig sperm motility parameters and quality, and elucidate the underlying molecular mechanisms. Our results revealed widespread expression of AANAT, ASMT, MT1, MT2, and NQO2 proteins in pig tissues, particularly in the testis. Specific localization patterns were observed in Leydig cells, reproductive epithelium, and columnar epithelium cells in the testis and cauda epididymis. Additionally, melatonin membrane receptors MT1 and MT2 were detected in boar sperm. Melatonin treatment significantly enhanced boar sperm motility parameters and quality, particularly with 10 nM melatonin treatment. Inhibition of the MT1 receptor, but not the MT2 receptor, resulted in decreased sperm motility, highlighting the pivotal role of the MT1 receptor in mediating melatonin's effects on boar sperm. Metabolomic analysis revealed significant alterations in sperm metabolites following melatonin supplementation, particularly in amino acid metabolism. Overall, our findings provide comprehensive insights into melatonin's mechanisms in improving boar sperm quality, suggesting its potential as a therapeutic agent for enhancing male fertility.

Lower plasma melatonin levels in non-hypoxic premature newborns associated with neonatal pain

We analyzed plasma melatonin levels in different groups of preterm newborns without hypoxia and their relationship with several perinatal variables like gestational age or neonatal pain. Prospective cohort study of preterm newborns (PTNB) without perinatal hypoxia, Apgar > 6 at 5 min, and oxygen needs on the third day of life. We compared melatonin levels at day 3 of life in different groups of non-hypoxic preterm infants (Student's t-tests, Mann-Whitney U, and chi2) and analyzed the relationship of melatonin with GA, birth weight, neonatal pain (Premature Infant Pain Profile (PIPP) scale), caffeine treatment, parenteral nutrition, or the development of free radical diseases (correlation study, linear regression) and factors associated with moderate/intense pain and free radical diseases (logistic regression analysis). Sixty-one preterm infants with gestational age (GA) of 30.7 ± 2.0 weeks with no oxygen requirements at day 3 of life were studied with plasma melatonin levels of 33.8 ± 12.01 pg/ml. Preterm infants weighing < 1250 g at birth had lower plasma melatonin levels (p = 0.05). Preterm infants with moderate or severe pain (PPIPP > 5) have lower melatonin levels (p = 0.01), and being preterm with PIPP > 5 is associated with lower plasma melatonin levels (p = 0.03). Being very preterm (GA < 32 GS), having low weight for gestational age (LWGA), receiving caffeine treatment, or requiring parenteral nutrition did not modify melatonin levels in non-hypoxic preterm infants (p = NS). Melatonin on day 3 of life in non-hypoxic preterm infants is not associated with later development of free radical diseases (BPD, sepsis, ROP, HIV, NEC).

CONCLUSION

We observed that preterm infants with moderate to severe pain have lower melatonin levels. These findings are relevant because they reinforce the findings of other authors that melatonin supplementation decreases pain and oxidative stress in painful procedures in premature infants. Further studies are needed to evaluate whether melatonin could be used as an analgesic in painful procedures in preterm infants.

TRIAL REGISTRATION

Trial registration was not required since this was an observational study.

WHAT IS KNOWN

• Melatonin is a potent antioxidant and free radical scavenger in newborns under stress conditions: hypoxia, acidosis, hypotension, painful procedures, or parenteral nutrition. • Pain stimulates the production of melatonin. • Various studies conclude that melatonin administration decreases pain during the neonatal period.

WHAT IS NEW

• Non-hypoxic preterm infants with moderate to severe pain (PIPP>5) have lower levels of melatonin. • Administration of caffeine and treatment with parenteral nutrition do not modify melatonin levels in non-hypoxic preterm infants.

A Comprehensive Review on the Role of Melatonin's Anesthetic Applications in Pediatric Care

Anesthesia is critical to pediatric care, ensuring the safety and comfort of children undergoing medical procedures. With a growing interest in alternative anesthetic agents, melatonin has emerged as a promising candidate due to its sedative, analgesic, anti-inflammatory, and neuroprotective properties. This comprehensive review explores the potential applications of melatonin in pediatric anesthesia. We delve into the pharmacological characteristics of melatonin, its anesthetic properties, and its clinical applications in pediatric care, including preoperative sedation, adjunct to general anesthesia, postoperative pain management, and prevention of emergence delirium. Additionally, we discuss the safety profile of melatonin, potential adverse effects, and comparative analysis with traditional anesthetics. Finally, we highlight future research directions to provide insights into melatonin's role in pediatric anesthesia and its implications for clinical practice.

Melatonin alleviates myocardial dysfunction through inhibition of endothelial-to-mesenchymal transition via the NF-κB pathway

Endothelial-to-mesenchymal transition (EndMT) is a complex biological process of cellular transdifferentiation by which endothelial cells (ECs) lose their characteristics and acquire mesenchymal properties, leading to cardiovascular remodeling and complications in the adult cardiovascular diseases environment. Melatonin is involved in numerous physiological and pathological processes, including aging, and has anti-inflammatory and antioxidant activities. This molecule is an effective therapeutic candidate for preventing oxidative stress, regulating endothelial function, and maintaining the EndMT balance to provide cardiovascular protection. Although recent studies have documented improved cardiac function by melatonin, the mechanism of action of melatonin on EndMT remains unclear. The present study investigated the effects of melatonin on induced EndMT by transforming growth factor-β2/interleukin-1β in both in vivo and in vitro models. The results revealed that melatonin reduced the migratory ability and reactive oxygen species levels of the cells and ameliorated mitochondrial dysfunction in vitro. Our findings indicate that melatonin prevents endothelial dysfunction and inhibits EndMT by activating related pathways, including nuclear factor kappa B and Smad. We also demonstrated that this molecule plays a crucial role in restoring cardiac function by regulating the EndMT process in the ischemic myocardial condition, both in vessel organoids and myocardial infarction (MI) animal models. In conclusion, melatonin is a promising agent that attenuates EC dysfunction and ameliorates cardiac damage compromising the EndMT process after MI.

Redox Homeostasis Alteration Is Restored through Melatonin Treatment in COVID-19 Patients: A Preliminary Study

Type II pneumocytes are the target of the SARS-CoV-2 virus, which alters their redox homeostasis to increase reactive oxygen species (ROS). Melatonin (MT) has antioxidant proprieties and protects mitochondrial function. In this study, we evaluated whether treatment with MT compensated for the redox homeostasis alteration in serum from COVID-19 patients. We determined oxidative stress (OS) markers such as carbonyls, glutathione (GSH), total antioxidant capacity (TAC), thiols, nitrites (NO2-), lipid peroxidation (LPO), and thiol groups in serum. We also studied the enzymatic activities of glutathione peroxidase (GPx), glutathione-S-transferase (GST), reductase (GR), thioredoxin reductase (TrxR), extracellular superoxide dismutase (ecSOD) and peroxidases. There were significant increases in LPO and carbonyl quantities (p ≤ 0.03) and decreases in TAC and the quantities of NO2-, thiols, and GSH (p < 0.001) in COVID-19 patients. The activities of the antioxidant enzymes such as ecSOD, TrxR, GPx, GST, GR, and peroxidases were decreased (p ≤ 0.04) after the MT treatment. The treatment with MT favored the activity of the antioxidant enzymes that contributed to an increase in TAC and restored the lost redox homeostasis. MT also modulated glucose homeostasis, functioning as a glycolytic agent, and inhibited the Warburg effect. Thus, MT restores the redox homeostasis that is altered in COVID-19 patients and can be used as adjuvant therapy in SARS-CoV-2 infection.

Peculiarities of melatonin levels in preterm infants

BACKGROUND

Melatonin plays an important role in organism functioning, child growth, and development. Of particular importance is melatonin for preterm infants. The aim of our research was to study the peculiarities of melatonin levels depending on various factors in preterm infants with gestational age (GA) of less than 34 weeks.

METHODS

The study involved 104 preterm infants with GA less than 34 weeks who were treated in the neonatal intensive care unit (NICU). The level of melatonin in urine samples was determined by an enzyme-linked immunosorbent assay.

RESULTS

Melatonin concentration was significantly lower in extremely and very preterm infants compared to moderate preterm (3.57 [2.10; 5.06] ng/ml vs. 4.96 [3.20; 8.42] ng/ml, p = 0.007) and was positively correlated with GA (Spearman r = 0.32; p < 0.001). Positive correlations were revealed between melatonin levels and Apgar scores at the 1st (Spearman r = 0.31; p = 0.001) and 5th minutes after birth (Spearman r = 0.35; p < 0.001). Melatonin levels were lower in newborns with respiratory distress syndrome (p = 0.011). No significant correlations were found between melatonin concentration and birth weight (Spearman r = 0.15; p = 0.130). There were no associations of melatonin concentrations and mode of delivery (p = 0.914), the incidence of early-onset sepsis (p = 0.370) and intraventricular hemorrhages (p = 0.501), and mechanical ventilation (p = 0.090). The results of multiple regression showed that gestational age at birth was the most significant predictor of melatonin level in preterm infants (B = 0.507; p = 0.001).

CONCLUSION

Gestational age and the Apgar score were associated with decreased melatonin levels in preterm infants. The level of melatonin in extremely and very preterm infants was lower compared to moderate preterm infants.

Emerging therapeutic strategies in hypoxic-ischemic encephalopathy: a focus on cognitive outcomes

Perinatal hypoxia-ischemia represents a significant risk to CNS development, leading to high mortality rates, diverse damages, and persistent neurological deficits. Despite advances in neonatal medicine in recent decades, the incidence of HIE remains substantial. Motor deficits can manifest early, while cognitive impairments may be diagnosed later, emphasizing the need for extended follow-up. This review aims to explore potential candidates for therapeutic interventions for hypoxic-ischemic encephalopathy (HIE), with a focus on cognitive deficits. We searched randomized clinical trials (RCT) that tested drug treatments for HIE and evaluated cognitive outcomes. The results included studies on erythropoietin, melatonin, magnesium sulfate, topiramate, and a combination of vitamin C and ibuprofen. Although there are several indications of the efficacy of these drugs among animal models, considering neuroprotective properties, the RCTs failed to provide complete effectiveness in the context of cognitive impairments derived from HIE. More robust RCTs are still needed to advance our knowledge and to establish standardized treatments for HIE.

Melatonin: the placental antioxidant and anti-inflammatory

Melatonin (N-acetyl-5-methoxytryptamine) is an indolamine hormone with many physiological and biological roles. Melatonin is an antioxidant, anti-inflammatory, free radical scavenger, circadian rhythm regulator, and sleep hormone. However, its most popular role is the ability to regulate sleep through the circadian rhythm. Interestingly, recent studies have shown that melatonin is an important and essential hormone during pregnancy, specifically in the placenta. This is primarily due to the placenta's ability to synthesize its own melatonin rather than depending on the pineal gland. During pregnancy, melatonin acts as an antioxidant and anti-inflammatory, which is necessary to ensure a stable environment for both the mother and the fetus. It is an essential antioxidant in the placenta because it reduces oxidative stress by constantly scavenging for free radicals, i.e., maintain the placenta's integrity. In a healthy pregnancy, the maternal immune system is constantly altered to accommodate the needs of the growing fetus, and melatonin acts as a key anti-inflammatory by regulating immune homeostasis during early and late gestation. This literature review aims to identify and summarize melatonin's role as a powerful antioxidant and anti-inflammatory that reduces oxidative stress and inflammation to maintain a favorable homeostatic environment in the placenta throughout gestation.

TET1 Regulates Skeletal Stem-Cell Mediated Cartilage Regeneration

OBJECTIVE

Adult skeletal stem cells (SSCs) that give rise to chondrocytes, osteocytes, and stromal cells as progeny have been shown to contribute to cartilage regeneration in osteoarthritis (OA). Understanding extrinsic and intrinsic regulators of SSC fate and function can therefore identify putative candidate factors to enhance cartilage regeneration. This study explores how the DNA hydroxymethylase Tet1 regulates SSC function in OA.

METHODS

We investigated the differences in the SSC lineage tree and differentiation potential in neonatal and adult Tet1+/+ and Tet1-/- mice with and without injury and upon OA induction and progression. Using RNA sequencing, the transcriptomic differences between SSCs and bone cartilage stroma progenitor cells (BCSPs) were identified in Tet1+/+ mice and Tet1-/- mice.

RESULTS

Loss of Tet1 skewed the SSC lineage tree by expanding the SSC pool and enhanced the chondrogenic potential of SSCs and BCSPs. Tet1 inhibition led to enhanced chondrogenesis in human SSCs and chondroprogenitors isolated from human cartilage. Importantly, TET1 inhibition in vivo in late stages of a mouse model of OA led to increased cartilage regeneration. Transcriptomic analyses of SSCs and BCSPs lacking Tet1 revealed pathway alterations in transforming growth factor β signaling, melatonin degradation, and cartilage development-associated genes. Lastly, we report that use of the hormone melatonin can dampen inflammation and improve cartilage health.

CONCLUSION

Although Tet1 is a broad epigenetic regulator, melatonin can mimic the inhibition ability of TET1 to enhance the chondrogenic ability of SSCs. Melatonin administration has the potential to be an attractive stem cell-based therapy for cartilage regeneration.

Unveiling the Protective Role of Melatonin in Osteosarcoma: Current Knowledge and Limitations

Melatonin, an endogenous neurohormone produced by the pineal gland, has received increased interest due to its potential anti-cancer properties. Apart from its well-known role in the sleep-wake cycle, extensive scientific evidence has shown its role in various physiological and pathological processes, such as inflammation. Additionally, melatonin has demonstrated promising potential as an anti-cancer agent as its function includes inhibition of tumorigenesis, induction of apoptosis, and regulation of anti-tumor immune response. Although a precise pathophysiological mechanism is yet to be established, several pathways related to the regulation of cell cycle progression, DNA repair mechanisms, and antioxidant activity have been implicated in the anti-neoplastic potential of melatonin. In the current manuscript, we focus on the potential anti-cancer properties of melatonin and its use in treating and managing pediatric osteosarcoma. This aggressive bone tumor primarily affects children and adolescents and is treated mainly by surgical and radio-oncological interventions, which has improved survival rates among affected individuals. Significant disadvantages to these interventions include disease recurrence, therapy-related toxicity, and severe/debilitating side effects that the patients have to endure, significantly affecting their quality of life. Melatonin has therapeutic effects when used for treating osteosarcoma, attributed to its ability to halt cancer cell proliferation and trigger apoptotic cell death, thereby enhancing chemotherapeutic efficacy. Furthermore, the antioxidative function of melatonin alleviates harmful side effects of chemotherapy-induced oxidative damage, aiding in decreasing therapeutic toxicities. The review concisely explains the many mechanisms by which melatonin targets osteosarcoma, as evidenced by significant results from several in vitro and animal models. Nevertheless, if further explored, human trials remain a challenge that could shed light and support its utility as an adjunctive therapeutic modality for treating osteosarcoma.

Significance of Melatonin in the Regulation of Circadian Rhythms and Disease Management

Melatonin, the 'hormone of darkness' is a neuronal hormone secreted by the pineal gland and other extra pineal sites. Responsible for the circadian rhythm and seasonal behaviour of vertebrates and mammals, melatonin is responsible for regulating various physiological conditions and the maintenance of sleep, body weight and the neuronal activities of the ocular sites. With its unique amphiphilic structure, melatonin can cross the cellular barriers and elucidate its activities in the subcellular components, including mitochondria. Melatonin is a potential scavenger of oxygen and nitrogen-reactive species and can directly obliterate the ROS and RNS by a receptor-independent mechanism. It can also regulate the pro- and anti-inflammatory cytokines in various pathological conditions and exhibit therapeutic activities against neurodegenerative, psychiatric disorders and cancer. Melatonin is also found to show its effects on major organs, particularly the brain, liver and heart, and also imparts a role in the modulation of the immune system. Thus, melatonin is a multifaceted candidate with immense therapeutic potential and is still considered an effective supplement on various therapies. This is primarily due to rectification of aberrant circadian rhythm by improvement of sleep quality associated with risk development of neurodegenerative, cognitive, cardiovascular and other metabolic disorders, thereby enhancing the quality of life.

Melatonin inhibits the formation of chemically induced experimental encapsulating peritoneal sclerosis through modulation of T cell differentiation by suppressing of NF-κB activation in dendritic cells

Encapsulating peritoneal sclerosis (EPS) is a severe complication of peritoneal dialysis (PD). Surgery is a therapeutic strategy for the treatment of complete intestinal obstruction. However, complete intestinal obstruction in long-term PD results in high mortality and morbidity rates after surgery. Immunopathogenesis participates in EPS formation: CD8, Th1, and Th17 cell numbers increased during the formation of EPS. The anti-inflammatory and immunomodulatory effects of melatonin may have beneficial effects on this EPS. In the present study, we determined that melatonin treatment significantly decreases the Th1 and Th17 cell populations in mice with EPS, decreases the production of IL-1β, TNF-α, IL-6, and IFN-γ, and increases the production of IL-10. The suppression of Th1 and Th17 cell differentiation by melatonin occurs through the inhibition of dendritic cell (DC) activation by affecting the initiation of the NF-κB signaling pathway in DCs. Our study suggests that melatonin has preventive potential against the formation of EPS in patients with PD.

Fate of melatonin orally administered in preterm newborns: Antioxidant performance and basis for neuroprotection

Preterm infants cannot counteract excessive reactive oxygen species (ROS) production due to preterm birth, leading to an excess of lipid peroxidation with malondialdehyde (MDA) production, capable of contributing to brain damage. Melatonin (ME), an endogenous brain hormone, and its metabolites, act as a free radical scavenger against ROS. Unfortunately, preterms have an impaired antioxidant system, resulting in the inability to produce and release ME. This prospective, multicenter, parallel groups, randomized, double-blind, placebo-controlled trial aimed to assess: (i) the endogenous production of ME in very preterm infants (gestational age ≤ 29 + 6 WE, 28 infants in the ME and 26 in the placebo group); (ii) the exogenous hormone availability and its metabolization to the main metabolite, 6-OH-ME after 15 days of ME oral treatment; (iii) difference of MDA plasma concentration, as peroxidation marker, after treatment. Blood was collected before the first administration (T1) and after 15 days of administration (T2). ME and 6-OH-ME were detected by liquid chromatography tandem mass spectrometry, MDA was measured by liquid chromatograph with fluorescence detection. ME and 6-OH-ME were not detectable in the placebo group at any study time-point. ME was absent in the active group at T1. In contrast, after oral administration, ME and 6-OH-ME resulted highly detectable and the difference between concentrations T2 versus T1 was statistically significant, as well as the difference between treated and placebo groups at T2. MDA levels seemed stable during the 15 days of treatment in both groups. Nevertheless, a trend in the percentage of neonates with reduced MDA concentration at T2/T1 was 48.1% in the ME group versus 38.5% in the placebo group. We demonstrated that very preterm infants are not able to produce endogenous detectable plasma levels of ME during their first days of life. Still, following ME oral administration, appreciable amounts of ME and 6-OH-ME were available. The trend of MDA reduction in the active group requires further clinical trials to fix the dosage, the length of ME therapy and to identify more appropriate indexes to demonstrate, at biological and clinical levels, the antioxidant activity and consequent neuroprotectant potential of ME in very preterm newborns.

Effects of fetal growth restriction on the perinatal neurovascular unit and possible treatment targets

The neurovascular unit (NVU) within the brain is a multicellular unit that synergistically acts to maintain blood-brain barrier function and meet cerebral metabolic demand. Recent studies have indicated disruption to the NVU is associated with neuropathology in the perinatal brain. Infants with fetal growth restriction (FGR) are known to be at increased risk of neurodevelopmental conditions including motor, learning, and behavioural deficits. There are currently no neuroprotective treatments for these conditions. In this review, we analyse large animal studies examining the effects of FGR on the perinatal NVU. These studies show altered vascularity in the FGR brain as well as blood-brain barrier dysfunction due to underlying cellular changes, mediated by neuroinflammation. Neuroinflammation is a key mechanism associated with pathological effects in the FGR brain. Hence, targeting inflammation may be key to preserving the multicellular NVU and providing neuroprotection in FGR. A number of maternal and postnatal therapies with anti-inflammatory components have been investigated in FGR animal models examining targets for amelioration of NVU disruption. Each therapy showed promise by uniquely ameliorating the adverse effects of FGR on multiple aspects of the NVU. The successful implementation of a clinically viable neuroprotective treatment has the potential to improve outcomes for neonates affected by FGR. IMPACT: Disruption to the neurovascular unit is associated with neuropathology in fetal growth restriction. Inflammation is a key mechanism associated with neurovascular unit disruption in the growth-restricted brain. Anti-inflammatory treatments ameliorate adverse effects on the neurovascular unit and may provide neuroprotection.

Biosynthesized Silver Nanoparticles from Cyperus conglomeratus Root Extract Inhibit Osteogenic Differentiation of Immortalized Mesenchymal Stromal Cells

BACKGROUND

Silver nanoparticles (AgNPs) are a focus of huge interest in biological research, including stem cell research. AgNPs synthesized using Cyperus conglomeratus root extract have been previously reported but their effects on mesenchymal stromal cells have yet to be investigated.

OBJECTIVES

The aim of this study is to investigate the effects of C. conglomeratus-derived AgNPs on adipogenesis and osteogenesis of mesenchymal stromal cells.

METHODS

AgNPs were synthesized using C. conglomeratus root extract, and the phytochemicals involved in AgNPs synthesis were analyzed using gas chromatography-mass spectrometry (GCMS). The cytotoxicity of the AgNPs was tested on telomerase-transformed immortalized human bone marrow-derived MSCs-hTERT (iMSC3) and human osteosarcoma cell line (MG-63) using MTT and apoptosis assays. The uptake of AgNPs by both cells was confirmed using inductively coupled plasma-optical emission spectrometry (ICP-OES). Furthermore, the effect of AgNPs on iMSC3 adipogenesis and osteogenesis was analyzed using stain quantification and reverse transcription- quantitative polymerase chain reaction (RT-qPCR).

RESULTS

The phytochemicals predominately identified in both the AgNPs and C. conglomeratus root extract were carbohydrates. The AgNP concentrations tested using MTT and apoptosis assays (0.5-64 µg/ml and 1,4 and 32 µg/ml, respectively) showed no significant cytotoxicity on iMSC3 and MG-63. The AgNPs were internalized in a concentration-dependent manner in both cell types. Additionally, the AgNPs exhibited a significant negative effect on osteogenesis but not on adipogenesis.

CONCLUSION

C. conglomeratus-derived AgNPs had an impact on the differentiation capacity of iMSC3. Our results indicated that C. conglomeratus AgNPs and the associated phytochemicals could exhibit potential medical applications.

Melatonin and its Emerging Physiological Role in Reproduction: A Review and Update

Melatonin is a neuroendocrine hormone secreted by the pineal gland. The secretion of melatonin follows a circadian rhythm controlled by the suprachiasmatic nucleus, and its secretion is synchronized with the changes in light and dark periods in nature, with the highest secretion level at night. Melatonin is a critical hormone that coordinates external light stimulation and cellular responses of the body. It transmits information about the environmental light cycle, including the circadian and seasonal rhythms, to the relevant tissues and organs in the body, which, along with changes in its secretion level, ensures that its regulated functional activities are adapted in response to changes in the outside environment. Melatonin takes beneficial actions mainly through the interaction with specific membrane-bound receptors, termed MT1 and MT2. Melatonin also acts as a scavenger of free radicals via non-receptor-mediated mechanism. For more than half of acentury melatonin has been associated with vertebrate reproduction, especially in the context of seasonal breeding. Though modern humans show little remaining reproductive seasonality, the relationships between melatonin and human reproduction continue to attract extensive attention. Melatonin plays important roles in improving mitochondrial function, reducing the damage of free radicals, inducing oocyte maturation, increasing fertilization rate and promoting embryonic development, which improves the outcomes of in vitro fertilization and embryo transfer. The present article reviews the progress that has been made in our evolving understanding of the physiological role of melatonin in reproduction and its potential clinical applications in reproductive medicine.

Melatonin as a Promising Anti-Inflammatory Agent in an In Vivo Animal Model of Sepsis-Induced Rat Liver Damage

Melatonin (MLT), earlier described as an effective anti-inflammatory agent, could be a beneficial adjunctive drug for sepsis treatment. This study aimed to determine the effects of MLT application in lipopolysaccharide (LPS)-induced sepsis in Wistar rats by determining the levels of liver tissue pro-inflammatory cytokines (TNF-α, IL-6) and NF-κB as well as hematological parameters indicating the state of sepsis. Additionally, an immunohistological analysis of CD14 molecule expression was conducted. Our research demonstrated that treatment with MLT prevented an LPS-induced increase in pro-inflammatory cytokines TNF-α and IL-6 and NF-κB levels, and in the neutrophil to lymphocyte ratio (NLR). On the other hand, MLT prevented a decrease in the blood lymphocyte number induced by LPS administration. Also, treatment with MLT decreased the liver tissue expression of the CD14 molecule observed after sepsis induction. In summary, in rats with LPS-induced sepsis, MLT was shown to be a significant anti-inflammatory agent with the potential to change the liver's immunological marker expression, thus ameliorating liver function.

Rapid Versus Slow Cooling Pasteurization of Donor Breast Milk: Does the Cooling Rate Effect Melatonin Reduction?

Background and Objective: There is a question as to whether melatonin levels in breast milk are impacted by the cooling rate postpasteurization. Past research that has used in the Australian donor bank's breast milk Holder Pasteurization technique has reported varying findings regarding melatonin levels postpasteurization. Where breast milk was cooled slowly, a significant reduction in breast milk melatonin levels was observed. Conversely, where a rapid cooling method was used, there was no significant reduction in melatonin levels. The aim of this study was to investigate whether the cooling process between the different pasteurization techniques impact on melatonin levels in breast milk postpasteurization. Materials and Methods: Twenty-seven nighttime breast milk samples were collected, with each sample divided into three; one remained unpasteurized, one was pasteurized and rapidly cooled to 4°C, and the other was pasteurized and cooled slowly to 4°C. Results: Melatonin levels were significantly reduced in both the rapidly cooled and slow cooled breast milk samples when compared to their unpasteurized counterpart (p < 0.001). There was no significant difference in melatonin levels between the two cooling methods (p = 0.91). Conclusion: This study showed that both the rapid and cooling pasteurization processes had a similar reduction in melatonin levels in breast milk. However, even after pasteurization melatonin was still present. Therefore, it is recommended that donor banks still take into consideration circadian timing hormones such as melatonin and the time of day breast milk is expressed.

Potential Adjuncts to Therapeutic Hypothermia to Mitigate Multiorgan Injury in Perinatal Hypoxia-Ischemia

Over the last 2 decades, therapeutic hypothermia has become the standard of care to reduce morbidity and mortality in neonates affected by moderate-to-severe hypoxic-ischemic encephalopathy (HIE). There is a significant interest in improving the neurologic outcomes of neonatal HIE, ranging from adjunctive therapy to therapeutic hypothermia. Importantly, the pathophysiologic mechanisms underlying HIE also affect multiple other organs, contributing to high morbidity and mortality in this patient population. This review focuses on the adjunct therapies currently under investigation to mitigate the impact of hypoxic-ischemic injury on the brain, kidneys, liver, heart, and gastrointestinal system.

Sericin and melatonin mitigate diethylnitrosamine-instigated testicular impairment in mice: Implications of oxidative stress, spermatogenesis, steroidogenesis, and modulation of Nrf2/WT1/SF-1 signaling pathways

AIMS

This study aimed to investigate the therapeutic influence of combination therapy with sericin and melatonin on attenuating diethylnitrosamine (DEN)-instigated testicular dysfunction in mice and defining the molecular mechanisms involved in orchestrating redox signaling pathways and restoring spermatogenesis and steroidogenesis.

MATERIALS AND METHODS

Different groups of male Swiss albino mice were established and injected with respective drugs intraperitoneally. Semen analysis, hormonal assays, and oxidative stress biomarkers were evaluated. Additionally, melatonin and its receptors, WT1, SF-1, vimentin, Nrf2, and ANXA1 expressions were assessed. Histopathological and ultrastructural features of the testes were investigated by semithin, SEM, and TEM analyses.

KEY FINDINGS

Exposure to DEN exhibited pathophysiological consequences, including a remarkable increase in lipid peroxidation associated with substantial diminutions in SOD, CAT, GPx, GSH, GSH:GSSG, and GST. Furthermore, it disrupted spermatozoa integrity, testosterone, FSH, LH, melatonin, and its receptors (MT1 and MT2) levels, implying spermatogenesis dysfunction. By contrast, treatment with sericin and melatonin significantly restored these disturbances. Interestingly, the combination therapy of sericin and melatonin noticeably augmented the Nrf2, WT1, and SF-1 expressions compared to DEN-treated mice, deciphering the amelioration perceived in antioxidant defense and spermatogenesis inside cells. Furthermore, immunohistochemical detection of ANXA1 alongside histopathological and ultrastructural analyses revealed evident maintenance of testicular structures without discernible inflammation or anomalies in mice administered with sericin and melatonin compared to the DEN-treated group.

SIGNIFICANCE

Our findings highlighted that treatment with sericin and melatonin alleviated the testicular tissues in mice from oxidative stress and dysregulated spermatogenesis and steroidogenesis engendered by DEN.

Impact of Treatment with Antioxidants as an Adjuvant to Standard Therapy in Patients with Septic Shock: Analysis of the Correlation between Cytokine Storm and Oxidative Stress and Therapeutic Effects

Cellular homeostasis is lost or becomes dysfunctional during septic shock due to the activation of the inflammatory response and the deregulation of oxidative stress. Antioxidant therapy administered alongside standard treatment could restore this lost homeostasis. We included 131 patients with septic shock who were treated with standard treatment and vitamin C (Vit C), vitamin E (Vit E), N-acetylcysteine (NAC), or melatonin (MT), in a randomized trial. Organ damage quantified by Sequential Organ Failure Assessment (SOFA) score, and we determined levels of Interleukins (IL) IL1β, Tumor necrosis factor alpha (TNFα), IL-6, monocyte chemoattractant protein-1 (MCP-1), Transforming growth factor B (TGFβ), IL-4, IL-10, IL-12, and Interferon-γ (IFNγ). The SOFA score decreased in patients treated with Vit C, NAC, and MT. Patients treated with MT had statistically significantly reduced of IL-6, IL-8, MCP-1, and IL-10 levels. Lipid peroxidation, Nitrates and nitrites (NO3- and NO2-), glutathione reductase, and superoxide dismutase decreased after treatment with Vit C, Vit E, NAC, and MT. The levels of thiols recovered with the use of Vit E, and all patients treated with antioxidants maintained their selenium levels, in contrast with controls (p = 0.04). The findings regarding oxidative stress markers and cytokines after treatment with antioxidants allow us to consider to future the combined use of antioxidants in a randomized clinical trial with a larger sample to demonstrate the reproducibility of these beneficial effects.

Melatonin Alleviates the Impairment of Muscle Bioenergetics and Protein Quality Control Systems in Leptin-Deficiency-Induced Obesity

Leptin is critically compromised in the major common forms of obesity. Skeletal muscle is the main effector tissue for energy modification that occurs as a result of the effect of endocrine axes, such as leptin signaling. Our study was carried out using skeletal muscle from a leptin-deficient animal model, in order to ascertain the importance of this hormone and to identify the major skeletal muscle mechanisms affected. We also examined the therapeutic role of melatonin against leptin-induced muscle wasting. Here, we report that leptin deficiency stimulates fatty acid β-oxidation, which results in mitochondrial uncoupling and the suppression of mitochondrial oxidative damage; however, it increases cytosolic oxidative damage. Thus, different nutrient-sensing pathways are disrupted, impairing proteostasis and promoting lipid anabolism, which induces myofiber degeneration and drives oxidative type I fiber conversion. Melatonin treatment plays a significant role in reducing cellular oxidative damage and regulating energy homeostasis and fuel utilization. Melatonin is able to improve both glucose and mitochondrial metabolism and partially restore proteostasis. Taken together, our study demonstrates melatonin to be a decisive mitochondrial function-fate regulator in skeletal muscle, with implications for resembling physiological energy requirements and targeting glycolytic type II fiber recovery.

Effects of Melatonin on Liver of D-Galactose-Induced Aged Mouse Model

Melatonin, a hormone secreted by the pineal gland of vertebrates, regulates sleep, blood pressure, and circadian and seasonal rhythms, and acts as an antioxidant and anti-inflammatory agent. We investigated the protective effects of melatonin against markers of D-galactose (D-Gal)-induced hepatocellular aging, including liver inflammation, hepatocyte structural damage, and non-alcoholic fatty liver. Mice were divided into four groups: phosphate-buffered saline (PBS, control), D-Gal (200 mg/kg/day), melatonin (20 mg/kg), and D-Gal (200 mg/kg) and melatonin (20 mg) cotreatment. The treatments were administered once daily for eight consecutive weeks. Melatonin treatment alleviated D-Gal-induced hepatocyte impairment. The AST level was significantly increased in the D-Gal-treated groups compared to that in the control group, while the ALT level was decreased compared to the melatonin and D-Gal cotreated group. Inflammatory genes, such as IL1-β, NF-κB, IL-6, TNFα, and iNOS, were significantly increased in the D-Gal aging model, whereas the expression levels of these genes were low in the D-Gal and melatonin cotreated group. Interestingly, the expression levels of hepatic steatosis-related genes, such as LXRα, C/EBPα, PPARα, ACC, ACOX1, and CPT-1, were markedly decreased in the D-Gal and melatonin cotreated group. These results suggest that melatonin suppresses hepatic steatosis and inflammation in a mouse model of D-Gal-induced aging.

Melatonin ameliorates atherosclerosis by suppressing S100a9-mediated vascular inflammation

Atherosclerosis (AS)-associated cardiovascular diseases are predominant causes of morbidity and mortality worldwide. Melatonin, a circadian hormone with anti-inflammatory activity, may be a novel therapeutic intervention for AS. However, the exact mechanism is unclear. This research intended to investigate the mechanism of melatonin in treating AS. Melatonin (20 mg/kg/d) was intraperitoneally administered in a high-fat diet (HFD)-induced AS model using apolipoprotein E-deficient (ApoE-/-) mice for 12 weeks. Immunohistochemical and immunofluorescence analyses, data-independent acquisition (DIA)-based protein profiling, ingenuity pathway analysis (IPA), and western blotting were employed to investigate the therapeutic effects of melatonin in treating HFD-induced AS. An adeno-associated virus (AAV) vector was further used to confirm the antiatherosclerotic mechanism of melatonin. Melatonin treatment markedly attenuated atherosclerotic lesions, induced stable phenotypic sclerotic plaques, inhibited macrophage infiltration, and suppressed the production of proinflammatory cytokines in ApoE-/- mice with HFD-induced AS. Notably, DIA-based quantitative proteomics together with IPA identified S100a9 as a pivotal mediator in the protective effects of melatonin. Moreover, melatonin significantly suppressed HFD-induced S100a9 expression at both the mRNA and protein levels. The overexpression of S100a9 significantly activated the NF-κB signaling pathway and markedly abolished the antagonistic effect of melatonin on HFD-induced vascular inflammation during atherogenesis. Melatonin exerts a significant antiatherogenic effect by inhibiting S100a9/NF-κB signaling pathway-mediated vascular inflammation. Our findings reveal a novel antiatherosclerotic mechanism of melatonin and underlie its potential clinical use in modulating AS with good availability and affordability.

An in silico investigation: Can melatonin serve as an adjuvant in NR1D1-linked chronotherapy for amyotrophic lateral sclerosis?

Chronobiology, which studies biological rhythms and their impacts on health, presents a potential avenue for treating amyotrophic lateral sclerosis. Clock gene-related therapies, focusing on genes responsible for regulating biological rhythms, may hold promise in the treatment. Among these clock genes, nuclear receptor subfamily 1 Group D member 1 (NR1D1) plays a vital role in neurodegenerative diseases. In this particular study, it was aimed to investigate the potential of FDA-approved drugs commonly used in amyotrophic lateral sclerosis treatment and melatonin, a hormone known for its role in regulating sleep-wake cycles, as ligands for clock gene-related therapy. The ligands were subjected to molecular docking and molecular dynamics simulation methods against the NR1D1 clock gene. These results suggested that combining melatonin with FDA-approved medications commonly used in the treatment might yield positive outcomes. This study provides preliminary data and lays the groundwork for future investigations involving in vitro (laboratory-based) and in vivo (animal or human-based) research on chronotherapy. In summary, this research highlights the potential of clock gene-related therapy utilizing melatonin in conjunction with FDA-approved drugs for amyotrophic lateral sclerosis treatment, offering insights into novel treatment strategies. The findings underscore the need for further studies to explore the effectiveness of this hypothetical approach in experimental and clinical settings.

Melatonin as a potential treatment for septic cardiomyopathy

Septic cardiomyopathy (SCM) is a common complication of sepsis contributing to high mortality rates. Its pathophysiology involves complex factors, including inflammatory cytokines, mitochondrial dysfunction, oxidative stress, and immune dysregulation. Despite extensive research, no effective pharmacological agent has been established for sepsis-induced cardiomyopathy. Melatonin, a hormone with diverse functions in the body, has emerged as a potential agent for SCM through its anti-oxidant, anti-inflammatory, anti-apoptotic, and cardioprotective roles. Through various molecular levels of its mechanism of action, it counterattacks the adverse event of sepsis. Experimental studies have mentioned that melatonin protects against many cardiovascular diseases and exerts preventive effects on SCM. Moreover, melatonin has been investigated in combination with other drugs such as antibiotics, resveratrol, and anti-oxidants showing synergistic effects in reducing inflammation, anti-oxidant, and improving cardiac function. While preclinical studies have demonstrated positive results, clinical trials are required to establish the optimal dosage, route of administration, and treatment duration for melatonin in SCM. Its safety profile, low toxicity, and natural occurrence in the human body provide a favorable basis for its clinical use. This review aims to provide an overview of the current evidence of the use of melatonin in sepsis-induced cardiomyopathy (SICM). Melatonin appears to be promising as a possible treatment for sepsis-induced cardiomyopathy and demands further investigation.

Melatonin Attenuates Sepsis-Induced Acute Lung Injury via Inhibiting Excessive Mitophagy

Background

Epidemiological studies have indicated that lung injury is a frequent complication of sepsis. Mitophagy is vital to multiple pathological processes and diseases; however, its influence on sepsis-induced acute lung injury remains elusive. Melatonin has multiple antioxidant action and anti-inflammatory effects, including regulating mitophagy and inflammatory cytokine expression. Whereas, little is known about the affection of melatonin and mitophagy on CLP-induced ALI.

Methods

The in vivo effect of melatonin on OPTN-mediated mitophagy was studied by CLP-induced ALI in a mouse model using C57BL/6 followed by treatment with vehicle and melatonin (30 mg/kg/d, intraperitoneal injection). ALI was assayed by lung wet /dry ratio, hematoxylin and eosin staining, and immunohistochemical staining. Signaling pathway changes were subsequently determined by Western blotting and immunofluorescence staining. The effects of melatonin on STAT3 activation and TNF-α production were detected by Western blotting, PCR, and immunohistochemical staining.

Results

Our results indicated that OPTN, mitophagy adaptors were significantly repressed in CLP-induced ALI, accompanied by overactivation of mitophagy and inflammation. At the same time, we found that melatonin treatment alleviated ALI caused by CLP, and the effect was highly correlated with OPTN-related mitophagy. Furthermore, we demonstrated that OPTN-related mitophagy, which was normalized by melatonin, blocked STAT3 involved epithelial barrier and inflammation in vivo.

Conclusion

Overall, our results confirm that mitophagy is adjusted by melatonin in the CLP-induced ALI. Moreover, manipulation of mitophagy through melatonin could be a possible treatment to reduce sepsis-associated lung injury.

Regulation of Adipose-Derived Stem Cell Activity by Melatonin Receptors in Terms of Viability and Osteogenic Differentiation

Melatonin is a hormone secreted mainly by the pineal gland and acts through the Mel1A and Mel1B receptors. Among other actions, melatonin significantly increases osteogenesis during bone regeneration. Human adipose-derived mesenchymal stem cells (ADSCs) are also known to have the potential to differentiate into osteoblast-like cells; however, inefficient culturing due to the loss of properties over time or low cell survival rates on scaffolds is a limitation. Improving the process of ADSC expansion in vitro is crucial for its further successful use in bone regeneration. This study aimed to assess the effect of melatonin on ADSC characteristics, including osteogenicity. We assessed ADSC viability at different melatonin concentrations as well as the effect on its receptor inhibitors (luzindole or 4-P-PDOT). Moreover, we analyzed the ADSC phenotype, apoptosis, cell cycle, and expression of MTNR1A and MTNR1B receptors, and its potential for osteogenic differentiation. We found that ADSCs treated with melatonin at a concentration of 100 µM had a higher viability compared to those treated at higher melatonin concentrations. Melatonin did not change the phenotype of ADSCs or induce apoptosis and it promoted the activity of some osteogenesis-related genes. We concluded that melatonin is safe, non-toxic to normal ADSCs in vitro, and can be used in regenerative medicine at low doses (100 μM) to improve cell viability without negatively affecting the osteogenic potential of these cells.

Natural Immunosuppressants as a Treatment for Chronic Insomnia Targeting the Inflammatory Response Induced by NLRP3/caspase-1/IL-1β Axis Activation: A Scooping Review

Chronic insomnia is an inflammatory-related disease with an important pathological basis for various diseases which is a serious threat to a person's physical and mental health. So far, many hypotheses have been proposed to explain the pathogenesis of insomnia, among which inflammatory mechanisms have become the focus of scientific attention. In this regard, the aim of the present scooping review is to evaluate the potential benefits of natural compounds in treatment of chronic insomnia targeting nucleotide-binding oligomerization domain (NOD)-like receptor-pyrin-containing protein 3 (NLRP3)/caspase-1/IL-1β axis as one of the most important activators of inflammatory cascades. The data show that compounds that have the potential to cause inflammation induce sleep disorders, and that inflammatory mediators are key molecules in regulating the sleep-related activity of neurons. In the inflammatory process of insomnia, the role of NLRP3 in the pathogenesis of insomnia has been gradually considered by researchers. NLRP3 is an intracellular sensor that recognizes the widest range of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). After identification and binding to damage factors, NLRP3 inflammasome is assembled to activate the caspase-1 and IL-1β. Increased production and secretion of IL-1β may be involved in central nervous system dysregulation of physiological sleep. The current scooping review reports the potential benefits of natural compounds that target NLRP3 inflammasome pathway activity and highlights the hypothesis which NLRP3 /caspase-1/IL-1β may serve as a potential therapeutic target for managing inflammation and improving symptoms in chronic insomnia.

Melatonin as a Therapy for Preterm Brain Injury: What Is the Evidence?

Despite significant improvements in survival following preterm birth in recent years, the neurodevelopmental burden of prematurity, with its long-term cognitive and behavioral consequences, remains a significant challenge in neonatology. Neuroprotective treatment options to improve neurodevelopmental outcomes in preterm infants are therefore urgently needed. Alleviating inflammatory and oxidative stress (OS), melatonin might modify important triggers of preterm brain injury, a complex combination of destructive and developmental abnormalities termed encephalopathy of prematurity (EoP). Preliminary data also suggests that melatonin has a direct neurotrophic impact, emphasizing its therapeutic potential with a favorable safety profile in the preterm setting. The current review outlines the most important pathomechanisms underlying preterm brain injury and correlates them with melatonin's neuroprotective potential, while underlining significant pharmacokinetic/pharmacodynamic uncertainties that need to be addressed in future studies.

Evaluation of the effect of direct-acting antiviral agents on melatonin level and lipid peroxidation in chronic hepatitis C patients

Background: Oxidative stress and its end products, such as malondialdehyde (MDA) play a leading role in the pathogenesis of hepatitis C. Melatonin is a hormone that helps regulate circadian rhythms, which likely play a role in infectious diseases in terms of susceptibility, clinical expression, and outcome. Objective: The present study was conducted to assess serum malondialdehyde and melatonin levels in patients with chronic hepatitis C infection before and after the intake of direct-acting antivirals. Method: Forty hepatitis C patients were the subjects of this study. While ten healthy volunteers who matched in age and socioeconomic status served as the control subjects. Malondialdehyde and melatonin were assayed in the serum of the three groups, and the results were statistically analyzed. Results: Hepatitis C patients had significantly higher malondialdehyde (p < 0.001) but significantly lower melatonin (p < 0.001) as compared to the healthy controls. After 12 weeks of treatment with direct-acting antivirals, the malondialdehyde level decreased significantly (p < 0.001) and the melatonin level increased significantly (p < 0.001). A significant negative correlation between malondialdehyde and melatonin was observed. Conclusion: The present findings suggest that treatment of hepatitis C patients with Direct-acting antivirals improves liver function parameters and antioxidant profiles.

Current and future therapeutic strategies for Alzheimer's disease: an overview of drug development bottlenecks

Alzheimer's disease (AD) is the most common chronic neurodegenerative disease worldwide. It causes cognitive dysfunction, such as aphasia and agnosia, and mental symptoms, such as behavioral abnormalities; all of which place a significant psychological and economic burden on the patients' families. No specific drugs are currently available for the treatment of AD, and the current drugs for AD only delay disease onset and progression. The pathophysiological basis of AD involves abnormal deposition of beta-amyloid protein (Aβ), abnormal tau protein phosphorylation, decreased activity of acetylcholine content, glutamate toxicity, autophagy, inflammatory reactions, mitochondria-targeting, and multi-targets. The US Food and Drug Administration (FDA) has approved five drugs for clinical use: tacrine, donepezil, carbalatine, galantamine, memantine, and lecanemab. We have focused on the newer drugs that have undergone clinical trials, most of which have not been successful as a result of excessive clinical side effects or poor efficacy. Although aducanumab received rapid approval from the FDA on 7 June 2021, its long-term safety and tolerability require further monitoring and confirmation. In this literature review, we aimed to explore the possible pathophysiological mechanisms underlying the occurrence and development of AD. We focused on anti-Aβ and anti-tau drugs, mitochondria-targeting and multi-targets, commercially available drugs, bottlenecks encountered in drug development, and the possible targets and therapeutic strategies for future drug development. We hope to present new concepts and methods for future drug therapies for AD.

A New Perspective on the Pathogenesis of Infantile Colic: Is Infantile Colic a Biorhythm Disorder?

OBJECTIVES

In this study, we investigated the relationship between infantile colic, migraine, and biorhythm regulation, by evaluating biochemical and molecular parameters.

STUDY DESIGN

Healthy infants with and without infantile colic were eligible for this prospective cohort study. A questionnaire was applied. Between the 6th and 8th postnatal weeks, day and night circadian histone gene H3f3b mRNA expression and spot urine excretion of serotonin, cortisol, and 6-sulphatoxymelatonin were analyzed.

RESULTS

Among the 95 infants included, 49 were diagnosed with infantile colic. In the colic group, defecation difficulty, sensitivity to light/sound, and maternal migraine frequency increased and sleep disruption was typical. In the melatonin analysis, the difference between day and night levels was significant in the control group, indicating an established circadian rhythm ( P = 0.014). In the colic group, there was no day-night difference ( P = 0.216) in melatonin, but serotonin levels were higher at night. In the cortisol analysis, day-night values were similar in both groups. Day-night variability of H3f3b mRNA levels between the groups was significant, indicating circadian rhythm disturbance in the colic group compared to the control group ( P = 0.003). Fluctuations in circadian genes and hormones expected in healthy rhythm were revealed in the control group, but were missing in the colic group.

CONCLUSION

Due to the gaps in the etipathogenesis in infantile colic, a unique effective agent has not been discovered so far. This study, which demonstrated for the first time that infantile colic is a biorhythm disorder using molecular methods, fills the gap in this regard and points to a completely different perspective in terms of treatment.

Enhancement of the SESN2-SHP cascade by melatonin ameliorates hepatic gluconeogenesis by inhibiting the CRBN-BTG2-CREBH signaling pathway

Melatonin is involved in the regulation of various biological functions. Here, we explored a novel molecular mechanism by which the melatonin-induced sestrin2 (SESN2)-small heterodimer partner (SHP) signaling pathway protects against fasting- and diabetes-mediated hepatic glucose metabolism. Various key gene expression analyses were performed and multiple metabolic changes were assessed in liver specimens and primary hepatocytes of mice and human participants. The expression of the hepatic cereblon (CRBN) and b-cell translocation gene 2 (BTG2) genes was significantly increased in fasting mice, diabetic mice, and patients with diabetes. Overexpression of Crbn and Btg2 increased hepatic gluconeogenesis by enhancing cyclic adenosine monophosphate (cAMP)-responsive element-binding protein H (CREBH), whereas this phenomenon was prominently ablated in Crbn null mice and Btg2-silenced mice. Interestingly, melatonin-induced SESN2 and SHP markedly reduced hepatic glucose metabolism in diabetic mice and primary hepatocytes, and this protective effect of melatonin was strikingly reversed by silencing Sesn2 and Shp. Finally, the melatonin-induced SESN2-SHP signaling pathway inhibited CRBN- and BTG2-mediated hepatic gluconeogenic gene transcription via the competition of BTG2 and the interaction of CREBH. Mitigation of the CRBN-BTG2-CREBH axis by the melatonin-SESN2-SHP signaling network may provide a novel therapeutic strategy to treat metabolic dysfunction due to diabetes.

Chorioamnionitis disrupts erythropoietin and melatonin homeostasis through the placental-fetal-brain axis during critical developmental periods

Introduction: Novel therapeutics are emerging to mitigate damage from perinatal brain injury (PBI). Few newborns with PBI suffer from a singular etiology. Most experience cumulative insults from prenatal inflammation, genetic and epigenetic vulnerability, toxins (opioids, other drug exposures, environmental exposure), hypoxia-ischemia, and postnatal stressors such as sepsis and seizures. Accordingly, tailoring of emerging therapeutic regimens with endogenous repair or neuro-immunomodulatory agents for individuals requires a more precise understanding of ligand, receptor-, and non-receptor-mediated regulation of essential developmental hormones. Given the recent clinical focus on neurorepair for PBI, we hypothesized that there would be injury-induced changes in erythropoietin (EPO), erythropoietin receptor (EPOR), melatonin receptor (MLTR), NAD-dependent deacetylase sirtuin-1 (SIRT1) signaling, and hypoxia inducible factors (HIF1α, HIF2α). Specifically, we predicted that EPO, EPOR, MLTR1, SIRT1, HIF1α and HIF2α alterations after chorioamnionitis (CHORIO) would reflect relative changes observed in human preterm infants. Similarly, we expected unique developmental regulation after injury that would reveal potential clues to mechanisms and timing of inflammatory and oxidative injury after CHORIO that could inform future therapeutic development to treat PBI. Methods: To induce CHORIO, a laparotomy was performed on embryonic day 18 (E18) in rats with transient uterine artery occlusion plus intra-amniotic injection of lipopolysaccharide (LPS). Placentae and fetal brains were collected at 24 h. Brains were also collected on postnatal day 2 (P2), P7, and P21. EPO, EPOR, MLTR1, SIRT1, HIF1α and HIF2α levels were quantified using a clinical electrochemiluminescent biomarker platform, qPCR, and/or RNAscope. MLT levels were quantified with liquid chromatography mass spectrometry. Results: Examination of EPO, EPOR, and MLTR1 at 24 h showed that while placental levels of EPO and MLTR1 mRNA were decreased acutely after CHORIO, cerebral levels of EPO, EPOR and MLTR1 mRNA were increased compared to control. Notably, CHORIO brains at P2 were SIRT1 mRNA deficient with increased HIF1α and HIF2α despite normalized levels of EPO, EPOR and MLTR1, and in the presence of elevated serum EPO levels. Uniquely, brain levels of EPO, EPOR and MLTR1 shifted at P7 and P21, with prominent CHORIO-induced changes in mRNA expression. Reductions at P21 were concomitant with increased serum EPO levels in CHORIO rats compared to controls and variable MLT levels. Discussion: These data reveal that commensurate with robust inflammation through the maternal placental-fetal axis, CHORIO impacts EPO, MLT, SIRT1, and HIF signal transduction defined by dynamic changes in EPO, EPOR, MLTR1, SIRT1, HIF1α and HIF2α mRNA, and EPO protein. Notably, ligand-receptor mismatch, tissue compartment differential regulation, and non-receptor-mediated signaling highlight the importance, complexity and nuance of neural and immune cell development and provide essential clues to mechanisms of injury in PBI. As the placenta, immune cells, and neural cells share many common, developmentally regulated signal transduction pathways, further studies are needed to clarify the perinatal dynamics of EPO and MLT signaling and to capitalize on therapies that target endogenous neurorepair mechanisms.

Pharmacotechnical, Physico-Chemical, and Antioxidant Evaluation of Newly Developed Capsule Formulations

The excess of free radicals causes numerous imbalances in the body that lead to premature aging, the degradation of internal structures, and the appearance of numerous pathologies responsible for the increased risk of premature death. The present work aims to evaluate the physical, chemical, pharmacotechnical, and antioxidant activity of newly achieved capsule formulations. These two formulations were F1_a.i., which contains melatonin:biotin:coenzyme Q10 (weight ratio of 1:2:60), and F2_a.i., which contains quercetin:resveratrol:biotin:coenzyme Q10 (weight ratio of 10:10:1:10). The adequate selection of the excipient types and amounts for final capsule formulations (F1_c.c., F2_c.c.) was based on preformulation studies performed on the powders containing active ingredients. The antioxidant activity assessed using three methods (ABTS, DPPH, and FRAP) compared with acid ascorbic as a positive control demonstrated that the F2_c.c. formulation possesses the strongest antioxidant capacity. The results confirmed the suitable formulation and the accurate selection of the types and amounts of active ingredients, as well as the auxiliary excipients used in newly developed capsule formulations as supplements with an excellent antioxidant effect on the human body.

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.

Comparing the efficacy in reducing brain injury of different neuroprotective agents following neonatal hypoxia-ischemia in newborn rats: a multi-drug randomized controlled screening trial

Intrapartum hypoxia-ischemia leading to neonatal encephalopathy (NE) results in significant neonatal mortality and morbidity worldwide, with > 85% of cases occurring in low- and middle-income countries (LMIC). Therapeutic hypothermia (HT) is currently the only available safe and effective treatment of HIE in high-income countries (HIC); however, it has shown limited safety or efficacy in LMIC. Therefore, other therapies are urgently required. We aimed to compare the treatment effects of putative neuroprotective drug candidates following neonatal hypoxic-ischemic (HI) brain injury in an established P7 rat Vannucci model. We conducted the first multi-drug randomized controlled preclinical screening trial, investigating 25 potential therapeutic agents using a standardized experimental setting in which P7 rat pups were exposed to unilateral HI brain injury. The brains were analysed for unilateral hemispheric brain area loss after 7 days survival. Twenty animal experiments were performed. Eight of the 25 therapeutic agents significantly reduced brain area loss with the strongest treatment effect for Caffeine, Sonic Hedgehog Agonist (SAG) and Allopurinol, followed by Melatonin, Clemastine, ß-Hydroxybutyrate, Omegaven, and Iodide. The probability of efficacy was superior to that of HT for Caffeine, SAG, Allopurinol, Melatonin, Clemastine, ß-hydroxybutyrate, and Omegaven. We provide the results of the first systematic preclinical screening of potential neuroprotective treatments and present alternative single therapies that may be promising treatment options for HT in LMIC.

Medical Prospect of Melatonin in the Intervertebral Disc Degeneration through Inhibiting M1-Type Macrophage Polarization via SIRT1/Notch Signaling Pathway

The study aims to explore the medical prospect of melatonin (MLT) and the underlying therapeutic mechanism of MLT-mediated macrophage (Mφ) polarization on the function of nucleus pulposus (NP) in intervertebral disc degeneration (IDD). RAW 264.7 Mφs were induced by lipopolysaccharide (LPS) to simulate Mφ polarization and the inflammatory reaction of Mφs with or without MLT were detected. Conditioned medium (CM) collected from these activated Mφs with or without MLT treatment were further used to incubate NP cells. The oxidative stress, inflammation and extracellular matrix (ECM) metabolism in NP cells were determined. Then, the changes in SIRT1/Notch signaling were detected. The agonist (SRT1720) and inhibitor (EX527) of SIRT1 were used to further explore the association among MLT. The interaction between SIRT1 and NICD was detected by immunoprecipitation (IP). Finally, puncture-induced rat IDD models were established and IDD degrees were clarified by X-ray, MRI, H&E staining and immunofluorescence (IF). The results of flow cytometry and inflammation detection indicated that LPS could induce M1-type Mφ polarization with pro-inflammatory properties. MLT significantly inhibited the aforementioned process and inhibited M1-type Mφ polarization, accompanied by the alleviation of inflammation. Compared with those without MLT, the levels of oxidative stress, pro-inflammatory cytokines and ECM catabolism in NP cells exposed to CM with MLT were markedly downregulated in a dose-dependent manner. The inhibition of SIRT1 and the enhancement of Notch were observed in activated Mφs and they can be reversed after MLT treatment. This prediction was further confirmed by using the SRT1720 and EX527 to activate or inhibit the signaling. The interaction between SIRT1 and NICD was verified by IP. In vivo study, the results of MRI, Pfirrmann grade scores and H&E staining demonstrated the degree of disc degeneration was significantly lower in the MLT-treated groups when compared with the IDD control group. The IF data showed M1-type Mφ polarization decreased after MLT treatment. MLT could inhibit M1-type Mφ polarization and ameliorate the NP cell injury caused by inflammation in vitro and vivo, which is of great significance for the remission of IDD. The SIRT1/Notch signaling pathway is a promising target for MLT to mediate Mφ polarization.

Plausibility of natural immunomodulators in the treatment of COVID-19-A comprehensive analysis and future recommendations

The COVID-19 pandemic has inflicted millions of deaths worldwide. Despite the availability of several vaccines and some special drugs approved for emergency use to prevent or treat this disease still, there is a huge concern regarding their effectiveness, adverse effects, and most importantly, their efficacy against the new variants. A cascade of immune-inflammatory responses is involved with the pathogenesis and severe complications with COVID-19. People with dysfunctional and compromised immune systems display severe complications, including acute respiratory distress syndrome, sepsis, multiple organ failure etc., when they get infected with the SARS-CoV-2 virus. Plant-derived natural immune-suppressant compounds, such as resveratrol, quercetin, curcumin, berberine, luteolin, etc., have been reported to inhibit pro-inflammatory cytokines and chemokines. Therefore, natural products with immunomodulatory and anti-inflammatory potential could be plausible targets to treat this contagious disease. This review aims to delineate the clinical trials status and outcomes of natural compounds with immunomodulatory potential in COVID-19 patients along with the outcomes of their in-vivo studies. In clinical trials several natural immunomodulators resulted in significant improvement of COVID-19 patients by diminishing COVID-19 symptoms such as fever, cough, sore throat, and breathlessness. Most importantly, they reduced the duration of hospitalization and the need for supplemental oxygen therapy, improved clinical outcomes in patients with COVID-19, especially weakness, and eliminated acute lung injury and acute respiratory distress syndrome. This paper also discusses many potent natural immunomodulators yet to undergo clinical trials. In-vivo studies with natural immunomodulators demonstrated reduction of a wide range of proinflammatory cytokines. Natural immunomodulators that were found effective, safe, and well tolerated in small-scale clinical trials are warranted to undergo large-scale trials to be used as drugs to treat COVID-19 infections. Alongside, compounds yet to test clinically must undergo clinical trials to find their effectiveness and safety in the treatment of COVID-19 patients.

High-Temperature Pasteurization Used at Donor Breast Milk Banks Reduces Melatonin Levels in Breast Milk

Background and Objective: Donor human milk banks are used when breast milk directly from mothers is unavailable or insufficient. Breast milk contains melatonin, which exhibits a 24-hour pattern. Melatonin promotes sleep onset and is barely detected in daytime milk but rises in the evening and peaks early in the morning. Melatonin supports the development of an infant's own circadian rhythm and is important for neurodevelopment. Currently, donor banks pasteurize breast milk using a Holder Pasteurization (HoP) technique where breast milk is treated at a high temperature (+62°) for 30 minutes before cooling to eliminate any pathogens before it is given to infants. It is not known how the pasteurization process affects the melatonin levels in breast milk. The aim of this study was to investigate whether the pasteurization process reduces melatonin levels in breast milk. Materials and Methods: Ten night-time breast milk samples were collected and each divided into two groups; one group remained unpasteurized and the other group was pasteurized using the HoP technique. Results: Melatonin levels between the unpasteurized and pasteurized groups were compared. Results showed that there was a significant reduction after pasteurization (mean ± standard deviation = 51.92 pg/mL ± 19.54 versus 39.66 pg/mL ± 13.05, p = 0.01). Conclusions: It is important to understand that pasteurization can reduce melatonin levels in breast milk because this hormone is considered important to support the neurodevelopment of infants, especially those born preterm. Further focus on the effect of pasteurization techniques on melatonin in donor breast milk is warranted.

Maternal melatonin supplementation shapes gut microbiota and protects against inflammation in early life

BACKGROUND

Gut microbiota colonization is critical for immune education and nutrient metabolism. Research shows that melatonin has beneficial effects as a therapy for many diseases via modulating gut dysbiosis. However, it is unclear whether melatonin alters gut microbiota colonization in early life.

METHODS

In the experimental group (Mel), mice were intraperitoneally injected with melatonin at 10 mg/kg body weight for embryonic days 14-16 and received drinking water containing 0.4 mg/mL melatonin until 28 days postpartum. In the control group (Ctrl), mice were injected with the same volume of 2.5% ethanol in saline and provided with standard water. Two more groups were created by treating neonatal mice with 20 mg/kg lipopolysaccharide (LPS) to induce inflammation, resulting in the groups Ctrl + LPS and Mel + LPS, respectively. We examined the gut microbiota of the neonatal mice in the Ctrl and Mel group on Days 7, 14, 21, and 28 post-birth. On Day 14, melatonin and short-chain fatty acids (SCFAs) concentrations were measured in the Ctrl and Mel group and the mice were treated with LPS to be evaluated for intestinal injury and inflammatory response 15 h post treatment. According to the result of the SCFAs concentrations, some neonatal mice were intraperitoneally injected with 500 mg/kg sodium butyrate (SB) from Days 11-13, intraperitoneally injected with 20 mg/kg LPS on Day 14, and then euthanized by carbon dioxide inhalation the next morning. Intestinal injury and inflammatory responses were evaluated in the Ctrl + LPS and SB + LPS groups, respectively.

RESULTS

By Day 14, it was evident that maternal melatonin supplementation significantly increased the relative abundance of Firmicutes in the ileal [61.03 (35.35 - 76.18) % vs. 98.02 (86.61 - 99.01) %, P = 0.003] and colonic [73.88 (69.77 - 85.99) % vs. 96.16 (94.57 - 96.34) %, P = 0.04] microbiota, the concentration of melatonin (0.79 ± 0.49 ng/ml vs. 6.11 ± 3.48 ng/ml, P = 0.008) in the gut lumen, and the fecal butyric acid (12.91 ± 5.74 μg/g vs. 23.58 ± 10.71 μg/g, P = 0.026) concentration of neonatal mice. Melatonin supplementation, and sodium butyrate treatment markedly alleviated intestinal injury and decreased inflammatory factors in neonatal mice.

CONCLUSION

This study suggests that maternal melatonin supplementation can shape the gut microbiota and metabolism of offspring under normal physiological conditions and protect them against LPS-induced inflammation in early life.

Melatonin and Cytokines Modulate Daily Instrumental Activities of Elderly People with SARS-CoV-2 Infection

The Comprehensive Geriatric Assessment analyzes the health and quality of life of the elderly. Basic and instrumental daily activities may be compromised due to neuroimmunoendocrine changes, and studies suggest that possible immunological changes occur during infections in the elderly. Thus, this study aimed to analyze cytokine and melatonin levels in serum and correlate the Comprehensive Geriatric Assessment in elderly patients with SARS-CoV-2 infection. The sample consisted of 73 elderly individuals, 43 of whom were without infection and 30 of whom had positive diagnoses of COVID-19. Blood samples were collected to quantify cytokines by flow cytometry and melatonin by ELISA. In addition, structured and validated questionnaires were applied to assess basic (Katz) and instrumental (Lawton and Brody) activities. There was an increase in IL-6, IL-17, and melatonin in the group of elderly individuals with infection. In addition, a positive correlation was observed between melatonin and IL-6 and IL-17 in elderly patients with SARS-CoV-2 infection. Furthermore, there was a reduction in the score of the Lawton and Brody Scale in the infected elderly. These data suggest that the melatonin hormone and inflammatory cytokines are altered in the serum of the elderly with SARS-CoV-2 infection. In addition, there is a degree of dependence, mainly regarding the performance of daily instrumental activities, in the elderly. The considerable impact on the elderly person's ability to perform everyday tasks necessary for independent living is an extremely important result, and changes in cytokines and melatonin probably are associated with alterations in these daily activities of the elderly.

Impaired Melatonin Secretion, Oxidative Stress and Metabolic Syndrome in Night Shift Work

Metabolic syndrome has been associated in many studies with working in shifts. Even if the mechanistic details are not fully understood, forced sleep deprivation and exposure to light, as happens during night shifts, or irregular schedules with late or very early onset of the working program, lead to a sleep-wake rhythm misalignment, metabolic dysregulation and oxidative stress. The cyclic melatonin secretion is regulated by the hypothalamic suprachiasmatic nuclei and light exposure. At a central level, melatonin promotes sleep and inhibits wake-signals. Beside this role, melatonin acts as an antioxidant and influences the functionality of the cardiovascular system and of different metabolic processes. This review presents data about the influence of night shifts on melatonin secretion and oxidative stress. Assembling data from epidemiological, experimental and clinical studies contributes to a better understanding of the pathological links between chronodisruption and the metabolic syndrome related to working in shifts.

Antiviral effect of melatonin on Japanese encephalitis virus infection involves inhibition of neuronal apoptosis and neuroinflammation in SH-SY5Y cells

Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, causes high mortality rates in humans and it is the most clinically important and common cause of viral encephalitis in Asia. To date, there is no specific treatment for JEV infection. Melatonin, a neurotropic hormone, is reported to be effective in combating various bacterial and viral infections. However, the effects of melatonin on JEV infection have not yet been studied. The investigation tested the antiviral effects of melatonin against JEV infection and elucidated the possible molecular mechanisms of inhibition. Melatonin inhibited the viral production in JEV-infected SH-SY5Y cells in a time- and dose-dependent manner. Time-of-addition assays demonstrated a potent inhibitory effect of melatonin at the post-entry stage of viral replication. Molecular docking analysis revealed that melatonin negatively affected viral replication by interfering with physiological function and/or enzymatic activity of both JEV nonstructural 3 (NS3) and NS5 protein, suggesting a possible underlying mechanism of JEV replication inhibition. Moreover, treatment with melatonin reduced neuronal apoptosis and inhibited neuroinflammation induced by JEV infection. The present findings reveal a new property of melatonin as a potential molecule for the further development of anti-JEV agents and treatment of JEV infection.

The neural addiction of cancer

The recently uncovered key role of the peripheral and central nervous systems in controlling tumorigenesis and metastasis has opened a new area of research to identify innovative approaches against cancer. Although the 'neural addiction' of cancer is only partially understood, in this Perspective we discuss the current knowledge and perspectives on peripheral and central nerve circuitries and brain areas that can support tumorigenesis and metastasis and the possible reciprocal influence that the brain and peripheral tumours exert on one another. Tumours can build up local autonomic and sensory nerve networks and are able to develop a long-distance relationship with the brain through circulating adipokines, inflammatory cytokines, neurotrophic factors or afferent nerve inputs, to promote cancer initiation, growth and dissemination. In turn, the central nervous system can affect tumour development and metastasis through the activation or dysregulation of specific central neural areas or circuits, as well as neuroendocrine, neuroimmune or neurovascular systems. Studying neural circuitries in the brain and tumours, as well as understanding how the brain communicates with the tumour or how intratumour nerves interplay with the tumour microenvironment, can reveal unrecognized mechanisms that promote cancer development and progression and open up opportunities for the development of novel therapeutic strategies. Targeting the dysregulated peripheral and central nervous systems might represent a novel strategy for next-generation cancer treatment that could, in part, be achieved through the repurposing of neuropsychiatric drugs in oncology.

Use of the Single Cell Gel Electrophoresis Assay for the Detection of DNA-protective Dietary Factors: Results of Human Intervention Studies

The single cell gel electrophoresis technique is based on the measurement of DNA migration in an electric field and enables to investigate via determination of DNA-damage the impact of foods and their constituents on the genetic stability. DNA-damage leads to adverse effects including cancer, neurodegenerative disorders and infertility. In the last 25 years approximately 90 human intervention trials have been published in which DNA-damage, formation of oxidized bases, alterations of the sensitivity towards reactive oxygen species and chemicals and of repair functions were investigated with this technique. In approximately 50% of the studies protective effects were observed. Pronounced protection was found with certain plant foods (spinach, kiwi fruits, onions), coffee, green tea, honey and olive oil. Also diets with increased contents of vegetables caused positive effects. Small amounts of certain phenolics (gallic acid, xanthohumol) prevented oxidative damage of DNA; with antioxidant vitamins and cholecalciferol protective effects were only detected after intake of doses that exceed the recommended daily uptake values. The evaluation of the quality of the studies showed that many have methodological shortcomings (lack of controls, no calibration of repair enzymes, inadequate control of the compliance and statistical analyses) which should be avoided in future investigations.

Pathophysiological basis and promise of experimental therapies for Gulf War Illness, a chronic neuropsychiatric syndrome in veterans

This article describes the pathophysiology and potential treatments for Gulf War Illness (GWI), which is a chronic neuropsychiatric illness linked to a combination of chemical exposures experienced by service personnel during the first Gulf War in 1991. However, there is currently no effective treatment for veterans with GWI. The article focuses on the current status and efficacy of existing therapeutic interventions in preclinical models of GWI, as well as potential perspectives of promising therapies. GWI stems from changes in brain and peripheral systems in veterans, leading to neurocognitive deficits, as well as physiological and psychological effects resulting from multifaceted changes such as neuroinflammation, oxidative stress, and neuronal damage. Aging not only renders veterans more susceptible to GWI symptoms, but also attenuates their immune capabilities and response to therapies. A variety of experimental models are being used to investigate the pathophysiology and develop therapies that have the ability to alleviate devastating symptoms. Over two dozen therapeutic interventions targeting neuroinflammation, mitochondrial dysfunction, neuronal injury, and neurogenesis are being tested, including agents such as curcumin, curcumin nanoparticles, monosodium luminol, melatonin, resveratrol, fluoxetine, rolipram, oleoylethanolamide, ketamine, levetiracetam, nicotinamide riboside, minocycline, pyridazine derivatives, and neurosteroids. Preclinical outcomes show that some agents have promise, including curcumin, resveratrol, and ketamine, which are being tested in clinical trials in GWI veterans. Neuroprotectants and other compounds such as monosodium luminol, melatonin, levetiracetam, oleoylethanolamide, and nicotinamide riboside appear promising for future clinical trials. Neurosteroids have been shown to have neuroprotective and disease-modifying properties, which makes them a promising medicine for GWI. Therefore, accelerated clinical studies are urgently needed to evaluate and launch an effective therapy for veterans displaying GWI.

Chronic Administration of Melatonin: Physiological and Clinical Considerations

Background: Exogenous melatonin is commonly used to treat insomnia, other sleep problems, and numerous medical illnesses, including Alzheimer’s disease, autism spectrum disorder, and mild cognitive impairment in adults and children. There is evolving information regarding issues with the use of chronic melatonin. Methods: The present investigation was a narrative review. Results: Melatonin usage has risen dramatically in recent years. Many countries only allow melatonin prescriptions. In the United States (U.S.), it is classified as a dietary supplement accessible over the counter and can be derived from animals, microorganisms, or, most commonly, made synthetically. No regulatory agency oversees its manufacturing or sale in the U.S. melatonin concentration of marketed preparations varies widely between product labels and manufacturers. Melatonin’s ability to induce sleep is detectable. However, it is modest for most people. Sleep length appears to be less important in sustained-release preparations. The optimal dosage is unknown, and routinely used amounts vary substantially. Melatonin’s short-term negative effects are minimal, resolve at medicine cessation, and do not usually prevent usage overall. Much research on long-term melatonin administration has found no difference between exogenous melatonin and placebo in terms of long-term negative effects. Conclusion: Melatonin at low to moderate dosages (approximately 5–6 mg daily or less) appears safe. Long-term usage appears to benefit certain patient populations, such as those with autism spectrum disorder. Studies investigating potential benefits in reducing cognitive decline and increased longevity are ongoing. However, it is widely agreed that the long-term effects of taking exogenous melatonin have been insufficiently studied and warrant additional investigation.