Therapeutic applications of melatonin

Development, Characterization, and Evaluation of Potential Systemic Toxicity of a Novel Oral Melatonin Formulation

The need to create safe materials for biomedical and pharmaceutical applications has become a significant driving force for the development of new systems. Therefore, a chitosan-coated copolymer of itaconic acid, acrylic acid, and N-vinyl caprolactam (IT-AA-NVC) was prepared by radical polymerization and subsequent coating via nanoprecipitation to give a system capable of sustained delivery of melatonin. Although melatonin brings undoubted benefits to the human body, aspects of the optimal dose, route, and time of administration for the obtaining of suitable treatment outcomes remain under discussion. The entrapment of melatonin in biocompatible polymeric systems can prevent its oxidation, decrease its toxicity, and provide an increased half-life, resulting in an enhanced pharmacokinetic profile with improved patient compliance. The structures of the biopolymer and conjugate were proven by FTIR, thermal properties were tested by DSC, and the morphologies were followed by SEM. The loading efficiency and in vitro release profile were studied by means of HPLC, and a delayed release profile with an initial burst was obtained. The potential systemic toxicity of the formulation was studied in vivo; a mild hepatotoxicity was observed following administration of the melatonin-loaded formulation to mice, both by histopathology and blood clinical biochemistry. Histopathology showed a mild nephrotoxicity as well; however, kidney clinical biochemistry did not support this.

Night shift work, sleep duration and endometrial cancer risk: A pooled analysis from the Epidemiology of Endometrial Cancer Consortium (E2C2)

Data on the role of circadian related factors in the etiology of endometrial cancer are scarce. We collected individual data on night shift work or daily sleep duration from 7,207 cases and 22,027 controls participating in 11 studies from the Epidemiology of Endometrial Cancer Consortium (E2C2). Main analyses were performed among postmenopausal women: 6,335 endometrial cancer cases and 18,453 controls. Using individual data, study-specific odd ratios (ORs) and their corresponding 95% confidence intervals (CIs) were estimated with logistic regression and pooled analyses were conducted using random-effects meta-analyses. A non-significant inverse association was observed between endometrial cancer and night shift work (OR=0.89, 95%CI=0.72-1.09; I2=0.0%, Pheterogeneity=0.676). Associations did not vary by shift type (permanent or rotating), or duration of night work. Categorizations of short (<7h) or long (≥9h) sleep duration were not associated with endometrial cancer risk (ORshort=1.02, 95%CI=0.95-1.10; I2=55.3%, Pheterogeneity=0.022; ORlong=0.93, 95%CI=0.81-1.06; I2=11.5%, Pheterogeneity=0.339). No associations were observed per 1-h increment of sleep (OR=0.98, 95%CI=0.95-1.01; I2=46.1%, Pheterogeneity=0.063), but an inverse association was identified among obese women (OR=0.93, 95%CI=0.89-0.98 per 1-h increment; I2=12.7%, Pheterogeneity=0.329). Overall, these pooled analyses provide evidence that night shift work and sleep duration are not strong risk factors for endometrial cancer in postmenopausal women.

Melatonin and TGF-β-Mediated Release of Extracellular Vesicles

The immune system, unlike other systems, must be flexible and able to "adapt" to fully cope with lurking dangers. The transition from intracorporeal balance to homeostasis disruption is associated with activation of inflammatory signaling pathways, which causes modulation of the immunology response. Chemotactic cytokines, signaling molecules, and extracellular vesicles act as critical mediators of inflammation and participate in intercellular communication, conditioning the immune system's proper response. Among the well-known cytokines allowing for the development and proper functioning of the immune system by mediating cell survival and cell-death-inducing signaling, the tumor necrosis factor α (TNF-α) and transforming growth factor β (TGF-β) are noteworthy. The high bloodstream concentration of those pleiotropic cytokines can be characterized by anti- and pro-inflammatory activity, considering the powerful anti-inflammatory and anti-oxidative stress capabilities of TGF-β known from the literature. Together with the chemokines, the immune system response is also influenced by biologically active chemicals, such as melatonin. The enhanced cellular communication shows the relationship between the TGF-β signaling pathway and the extracellular vesicles (EVs) secreted under the influence of melatonin. This review outlines the findings on melatonin activity on TGF-β-dependent inflammatory response regulation in cell-to-cell communication leading to secretion of the different EV populations.

The Effect of Local Melatonin Application Following the Removal of an Impacted Mandibular Third Molar

PURPOSE

Pain, swelling, limitation of the mouth opening, development of intra-bony defects, and bone loss are common side effects of removing the impacted third molar. The purpose of this study was to measure the association of applying melatonin in the socket of an impacted mandibular third molar with osteogenic activity and the anti-inflammatory effects.

METHODS

This prospective, randomized, blinded trial comprised of patients who required removal of the impacted mandibular third molar. The patients were divided into two groups (n = 19) as follows: melatonin group (3 mg of melatonin into 2 ml of 2% hydroxyethyl cellulose gel was packed into the socket) and placebo group (2 ml of 2% hydroxyethyl cellulose gel was placed in the socket). The primary outcome was bone density, measured using Hounsfield unit immediately after surgery and 6 months later. Secondary outcome variables included serum osteoprotegerin level (Ng/ml) that measured immediately, 4 weeks and 6 months postoperatively. Other clinical outcome measures were pain by visual analog scale, maximum mouth opening (MMO) (millimeter), and swelling (millimeter) that were evaluated immediately, 1, 3, and 7 days postoperatively. The data were analyzed by independent t-test of Wilcoxon's rank-sum, analysis of variance, and generalized estimating equation (P ≤ .05).

RESULTS

Thirty-eight patients (25 female and 13 males) with a median age of 27 years were enrolled in the study. There was no statistical significance in bone density observed in both groups [melatonin group: 978.5(951.3-1015.8), control group: 965.8 (924.6-998.7), P = .1]. Alternatively, there were statistically significant improvements in osteoprotegerin levels (on week 4), MMO (on day1), and swelling (on day 3) in the melatonin group compared to those in the placebo group [1.9(1.4-2.4), 39.68 ± 1.35, and 14.36 ± 0.80 versus 1.5(1.2-1.4); 38.33 ± 1.20, and 14.88 ± 0.59; P = .02, .003, 0.031, respectively]. The pain values showed statistically significant improvement throughout the follow-up period in the melatonin group compared to the placebo group [5(3-8), 2(1-5), and 0(0-2) versus 7(6-8), 5(4-6), and 2(1-3); P < .001, respectively].

CONCLUSIONS

The results support the anti-inflammatory effect of melatonin in reducing the pain scale and swelling. Furthermore, it plays a role in the improvement of MMO. On the other hand, the osteogenic activity of melatonin could not be detected.

Pharmacological agents for the prevention of colistin-induced nephrotoxicity

Background

Colistin is a polymyxin antibiotic which has been used for treatment of Gram-negative infections, but it was withdrawn due to its nephrotoxicity. However, colistin has gained its popularity in recent years due to the reemergence of multidrug resistant Gram-negative infections and drug-induced toxicity is considered as the main obstacle for using this valuable antibiotic.

Results

In total, 30 articles, including 29 animal studies and one clinical trial were included in this study. These compounds, including aged black garlic extract, albumin fragments, alpha lipoic acid, astaxanthin, baicalein, chrysin, cilastatin, colchicine, curcumin, cytochrome c, dexmedetomidine, gelofusine, grape seed proanthocyanidin extract, hesperidin, luteolin, lycopene, melatonin, methionine, N-acetylcysteine, silymarin, taurine, vitamin C, and vitamin E exhibited beneficial effects in most of the published works.

Conclusions

In this review, the authors have attempted to review the available literature on the use of several compounds for prevention or attenuation of colistin-induced nephrotoxicity. Most of the studied compounds were potent antioxidants, and it seems that using antioxidants concomitantly can have a protective effect during the colistin exposure.

Anti-Inflammatory Effects of Melatonin in Rats with Induced Type 2 Diabetes Mellitus

Introduction: Insulin resistance is associated with a pro-inflammatory state increasing the risk for complications in patients with type 2 diabetes mellitus (T2DM). In addition to its chronobiotic effects, the pineal hormone melatonin is known to exert anti-inflammatory and antioxidant effects. Melatonin was also suggested to affect insulin secretion. The aim of this study was therefore to investigate the effect of melatonin on inflammation in diabetic rats and to study the possible involvement of the melatonin receptor, MT2. Materials and Methods: Male Sprague Dawley rats were randomly divided into four experimental groups (n = 10 per group): (1) control, (2) streptozotocin/nicotinamide induced diabetes type 2 (T2DM), (3) T2DM treated with melatonin (500 µg/kg/day), and (4) T2DM treated with melatonin (500 µg/kg/day for 6 weeks) and the selective MT2 receptor antagonist luzindole (0.25 g/kg/day for 6 weeks). Blood samples were taken for biochemical parameters and various tissue samples (liver, adipose tissue, brain) were removed for immunohistochemistry (IHC), Western blot (WB), and Q-PCR analyses, respectively. Results: Melatonin significantly reduced increased blood levels of liver transaminases (AST, ALT), blood urea nitrogen (BUN), triglyceride, very low-density lipoprotein (VLDL), and cholesterol in diabetic rats with luzindole treatment partly reversing this effect regarding the lipids. Furthermore, the liver and adipose tissues of T2DM rats treated with melatonin showed lower expression of the inflammatory markers IL-1β, IL-6, TNF-α, and NF-κB as compared to the T2DM group without melatonin. The results also showed that the MT2 receptor is at least partly involved in the protective effects of melatonin. Conclusions: Our results suggest that melatonin exerts relevant anti-inflammatory effects on various tissues in type 2 diabetic rats.

On the Interactions of Melatonin/β-Cyclodextrin Inclusion Complex: A Novel Approach Combining Efficient Semiempirical Extended Tight-Binding (xTB) Results with Ab Initio Methods

Melatonin (MT) is a molecule of paramount importance in all living organisms, due to its presence in many biological activities, such as circadian (sleep-wake cycle) and seasonal rhythms (reproduction, fattening, molting, etc.). Unfortunately, it suffers from poor solubility and, to be used as a drug, an appropriate transport vehicle has to be developed, in order to optimize its release in the human tissues. As a possible drug-delivery system, β-cyclodextrin (βCD) represents a promising scaffold which can encapsulate the melatonin, releasing when needed. In this work, we present a computational study supported by experimental IR spectra on inclusion MT/βCD complexes. The aim is to provide a robust, accurate and, at the same time, low-cost methodology to investigate these inclusion complexes both with static and dynamic simulations, in order to study the main actors that drive the interactions of melatonin with β-cyclodextrin and, therefore, to understand its release mechanism.

Modulation of the tumor microenvironment (TME) by melatonin

The tumor microenvironment (TME) includes a number of non-cancerous cells that affect cancer cell survival. Although CD8+ T lymphocytes and natural killer (NK) cells suppress tumor growth through induction of cell death in cancer cells, there are various immunosuppressive cells such as regulatory T cells (Tregs), tumor-associated macrophages (TAMs), cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), etc., which drive cancer cell proliferation. These cells may also support tumor growth and metastasis by stimulating angiogenesis, epithelial-mesenchymal transition (EMT), and resistance to apoptosis. Interactions between cancer cells and other cells, as well as molecules released into EMT, play a key role in tumor growth and suppression of antitumoral immunity. Melatonin is a natural hormone that may be found in certain foods and is also available as a drug. Melatonin has been demonstrated to modulate cell activity and the release of cytokines and growth factors in TME. The purpose of this review is to explain the cellular and molecular mechanisms of cancer cell resistance as a result of interactions with TME. Next, we explain how melatonin affects cells and interactions within the TME.

Tryptophan: From Diet to Cardiovascular Diseases

Cardiovascular disease (CVD) is one of the major causes of mortality worldwide. Inflammation is the underlying common mechanism involved in CVD. It has been recently related to amino acid metabolism, which acts as a critical regulator of innate and adaptive immune responses. Among different metabolites that have emerged as important regulators of immune and inflammatory responses, tryptophan (Trp) metabolites have been shown to play a pivotal role in CVD. Here, we provide an overview of the fundamental aspects of Trp metabolism and the interplay between the dysregulation of the main actors involved in Trp metabolism such as indoleamine 2, 3-dioxygenase 1 (IDO) and CVD, including atherosclerosis and myocardial infarction. IDO has a prominent and complex role. Its activity, impacting on several biological pathways, complicates our understanding of its function, particularly in CVD, where it is still under debate. The discrepancy of the observed IDO effects could be potentially explained by its specific cell and tissue contribution, encouraging further investigations regarding the role of this enzyme. Thus, improving our understanding of the function of Trp as well as its derived metabolites will help to move one step closer towards tailored therapies aiming to treat CVD.

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.

Melatonin rescues cerebral ischemic events through upregulated tunneling nanotube-mediated mitochondrial transfer and downregulated mitochondrial oxidative stress in rat brain

BACKGROUND

Cerebral ischemic events, comprising of excitotoxicity, reactive oxygen production, and inflammation, adversely impact the metabolic-redox circuit in highly active neuronal metabolic profile which maintains energy-dependent brain activities. Therefore, we investigated neuro-regenerative potential of melatonin (Mel), a natural biomaterial secreted by pineal gland.

METHODS

We specifically determined whether Mel could influence tunneling nanotubes (TNTs)-mediated transfer of functional mitochondria (Mito) which in turn may alter membrane potential, oxidative stress and apoptotic factors. In vitro studies assessed the effects of Mito on levels of cytochrome C, mitochondrial transfer, reactive oxygen species, membrane potential and mass, which were all further enhanced by Mel pre-treatment, whereas in vivo studies examined brain infarct area (BIA), neurological function, inflammation, brain edema and integrity of neurons and myelin sheath in control, ischemia stroke (IS), IS + Mito and IS + Mel-Mito group rats.

RESULTS

Results showed that Mel pre-treatment significantly increased mitochondrial transfer and antioxidants, and inhibited apoptosis. Mel-pretreated Mito also significantly reduced BIA with improved neurological function. Apoptotic, oxidative-stress, autophagic, mitochondrial/DNA-damaged biomarkers indices were also improved.

CONCLUSION

Conclusively, Mel is a potent biomaterial which could potentially impart neurogenesis through repairing impaired metabolic-redox circuit via enhanced TNT-mediated mitochondrial transfer, anti-oxidation, and anti-apoptotic activities in ischemia.

Metabolic Anti-Cancer Effects of Melatonin: Clinically Relevant Prospects

Metabolic reprogramming characterized by alterations in nutrient uptake and critical molecular pathways associated with cancer cell metabolism represents a fundamental process of malignant transformation. Melatonin (N-acetyl-5-methoxytryptamine) is a hormone secreted by the pineal gland. Melatonin primarily regulates circadian rhythms but also exerts anti-inflammatory, anti-depressant, antioxidant and anti-tumor activities. Concerning cancer metabolism, melatonin displays significant anticancer effects via the regulation of key components of aerobic glycolysis, gluconeogenesis, the pentose phosphate pathway (PPP) and lipid metabolism. Melatonin treatment affects glucose transporter (GLUT) expression, glucose-6-phosphate dehydrogenase (G6PDH) activity, lactate production and other metabolic contributors. Moreover, melatonin modulates critical players in cancer development, such as HIF-1 and p53. Taken together, melatonin has notable anti-cancer effects at malignancy initiation, progression and metastasing. Further investigations of melatonin impacts relevant for cancer metabolism are expected to create innovative approaches supportive for the effective prevention and targeted therapy of cancers.

Adjuvant use of melatonin for relieving symptoms of painful diabetic neuropathy: results of a randomized, double-blinded, controlled trial

PURPOSE

The trial aimed to investigate the effectiveness of exogenous melatonin as an adjuvant to pregabalin for relief of pain in patients suffering from painful diabetic neuropathy (PDN).

PATIENTS AND METHODS

This randomized, double-blind, placebo-controlled trial was carried out between October 2019 and December 2020 in an outpatient specialty clinic in Iran. One-hundred-three type 2 diabetic patients suffering from PDN were randomized into either the melatonin group (n = 52) or the placebo group (n = 51). Besides pregabalin at a dose of 150 mg per day, patients started with melatonin or an identical placebo, at a dose of 3 mg/day at bedtime for 1 week, which was augmented to 6 mg/day for further 7 weeks. The primary outcomes were changes in mean NRS (numerical rating scale) pain score from baseline to endpoint and responder rate (patients with a reduction of 50% and higher in average pain score compared with baseline). Secondary endpoints were changes in mean NRS pain-related sleep-interference score, overall improvement evaluated by Patient and Clinical Global Impressions of Change (PGIC, CGIC), and impact of the intervention on patient's Health-related quality of life (QOL). All analyses were conducted on an Intention-to-Treat (ITT) analysis data set.

RESULTS

At the study endpoint, treatment with melatonin resulted in a considerably higher reduction in the mean NRS pain score in comparison with placebo (4.2 ± 1.83 vs. 2.9 ± 1.56; P-value < 0.001). In terms of treatment responders, a greater proportion of melatonin-treated patients satisfied the responder criterion than placebo-treated patients (63.5% vs. 43.1%). Melatonin also reduced pain-related sleep interference scores more than did placebo (3.38 ± 1.49 vs. 2.25 ± 1.26; P-value < 0.001). Further, at the endpoint, more improvement was also seen in terms of PGIC, CGIC, and Health-related QOL in patients treated with melatonin than placebo. Melatonin was also well tolerated.

CONCLUSION

The present results showed that melatonin as an adjunct therapy to pregabalin might be helpful for use in patients with PDN. However, confirmation of these results requires further studies.

The Effects of Melatonin Supplementation on Sleep Quality and Assessment of the Serum Melatonin in ICU Patients: A Randomized Controlled Trial

OBJECTIVES

To evaluate whether the use of exogenous melatonin affects sleep, reduces the prevalence of delirium, and decreases the need for analgosedation and to assess whether serum melatonin indices correlate with exogenous administration in critically ill patients.

DESIGN

Double-blind, randomized, placebo-controlled study.

SETTING

Multicenter ICUs of two tertiary hospitals.

PATIENTS

A total of 203 adult patients who were admitted to the ICU and administered with analgesics and/or sedatives.

INTERVENTIONS

Oral melatonin (10 mg) or placebo for up to seven consecutive nights.

MEASUREMENTS AND MAIN RESULTS

The number of observed sleeping hours at night was assessed by the bedside nurse. Sleep quality was evaluated using the Richards Campbell Questionnaire Sleep (RCSQ). The prevalence of delirium, pain, anxiety, adverse reactions, duration of mechanical ventilation, length of ICU and hospital stays, and doses of sedative and analgesic drugs administered were recorded. The use of analgesics and sedatives was assessed daily. Melatonin levels were determined by enzyme-linked immunosorbent assay. Based on the RCSQ results, sleep quality was assessed to be better in the melatonin group than that in the placebo group with a mean (SD) of 69.7 (21.2) and 60.7 (26.3), respectively (p = 0.029). About 45.8% and 34.4% of participants in the melatonin and placebo groups had very good sleep (risk ratio, 1.33; 95% CI, 0.94-1.89), whereas 3.1% and 14.6% had very poor sleep (risk ratio, 0.21; 95% CI, 0.06-0.71), respectively. No significant difference was observed regarding the days free of analgesics or sedatives, the duration of night sleep, and the occurrence of delirium, pain, and anxiety. Melatonin serum peak levels at 2 AM were 150 pg/mL (range, 125-2,125 pg/mL) in the melatonin group and 32.5 pg/mL (range, 18.5-35 pg/mL) in the placebo group (p < 0.001).

CONCLUSIONS

Melatonin was associated with better sleep quality, which suggests its possible role in the routine care of critically ill patients in the future.

Microscopic Interactions of Melatonin, Serotonin and Tryptophan with Zwitterionic Phospholipid Membranes

The interactions at the atomic level between small molecules and the main components of cellular plasma membranes are crucial for elucidating the mechanisms allowing for the entrance of such small species inside the cell. We have performed molecular dynamics and metadynamics simulations of tryptophan, serotonin, and melatonin at the interface of zwitterionic phospholipid bilayers. In this work, we will review recent computer simulation developments and report microscopic properties, such as the area per lipid and thickness of the membranes, atomic radial distribution functions, angular orientations, and free energy landscapes of small molecule binding to the membrane. Cholesterol affects the behaviour of the small molecules, which are mainly buried in the interfacial regions. We have observed a competition between the binding of small molecules to phospholipids and cholesterol through lipidic hydrogen-bonds. Free energy barriers that are associated to translational and orientational changes of melatonin have been found to be between 10-20 kJ/mol for distances of 1 nm between melatonin and the center of the membrane. Corresponding barriers for tryptophan and serotonin that are obtained from reversible work methods are of the order of 10 kJ/mol and reveal strong hydrogen bonding between such species and specific phospholipid sites. The diffusion of tryptophan and melatonin is of the order of 10-7 cm2/s for the cholesterol-free and cholesterol-rich setups.

Chronobiology and Chronotherapy in Depression: Current Knowledge and Chronotherapeutic Promises

Background:

Depression is a heavily prevalent mental disorder. Symptoms of depression extend beyond mood, cognition, and behavior to include a spectrum of somatic manifestations in all organic systems. Changes in sleep and neuroendocrine rhythms are especially prominent, and disruptions of circadian rhythms have been closely related to the neurobiology of depression. With the advent of increased research in chronobiology, various pathophysiologic mechanisms have been proposed, including anomalies of sleep architecture, the effects of clock gene polymorphisms in monoamine metabolism, and the deleterious impact of social zeitgebers. The identification of these chronodisruptions has propelled the emergence of several chronotherapeutic strategies, both pharmacological and non-pharmacological, with varying degrees of clinical evidence.

Methods:

The fundamental objective of this review is to integrate current knowledge about the role of chronobiology and depression and to summarize the interventions developed to resynchronize biorhythms both within an individual and with geophysical time.

Results:

We have found that among the non-pharmacological alternatives, triple chronotherapywhich encompasses bright light therapy, sleep deprivation therapy, and consecutive sleep phase advance therapy-has garnered the most considerable scientific interest. On the other hand, agomelatine appears to be the most promising pharmacological option, given its unique melatonergic pharmacodynamics.

Conclusions:

Research in chronotherapy as a treatment for depression is currently booming. Novel interventions could play a significant role in adopting new options for the treatment of depression, with Tripe Cronotherapy standing out as the most promising treatment.

The role of melatonin and its analogues in epilepsy

Extensive research has gone into proposing a promising link between melatonin administration and attenuation of epileptic activity, the majority of which suggest its propensity as an antiseizure with antioxidant and neuroprotective properties. In the past few years, a number of studies highlighting the association of the melatonergic ligands with epilepsy have also emerged. In this context, our review is based on discussing the recent studies and various mechanisms of action that the said category of drugs exhibit in the context of being therapeutically viable antiseizure drugs. Our search revealed several articles on the four major drugs i.e. melatonin, agomelatine, ramelteon and piromelatine along with other melatonergic agonists like tasimelteon and TIK-301. Our review is suggestive of antiseizure effects of both melatonin and its analogues; however, extensive research work is still required to study their implications in the treatment of persons with epilepsy. Further evaluation of melatonergic signaling pathways and mechanisms may prove to be helpful in the near future and might prove to be a significant advance in the field of epileptology.

Melatonin and gastrointestinal cancers: Current evidence based on underlying signaling pathways

Gastrointestinal (GI) cancers, leading causes of cancer-related deaths, have been serious challenging human diseases up to now. Because of high rates of mortality, late-stage diagnosis, metastasis to distant locations, and low effectiveness and adverse events of routine standard therapies, the quality of life and survival time are low in patients with GI cancers. Hence, many efforts need to be done to explore and find novel efficient treatments. Beneficial effects of melatonin have been reported in a wide variety of human diseases. Melatonin has antioxidant, anti-inflammatory, antimicrobial, and anticancer effects. Various studies have showed the regulatory effects of melatonin on apoptotsis, autophagy and angiogenesis; these properties result in the inhibition of invasion, migration, and proliferation of GI cancer cells in vivo and in vitro. Together, this review suggests that melatonin in combination with anticancer agents may improve the efficacy of routine medicine and survival rate of patients with cancer.

Cellular absorption of small molecules: free energy landscapes of melatonin binding at phospholipid membranes

Free energy calculations are essential to unveil mechanisms at the atomic scale such as binding of small solutes and their translocation across cell membranes, eventually producing cellular absorption. Melatonin regulates biological rhythms and is directly related to carcinogenesis and neurodegenerative disorders. Free energy landscapes obtained from well-tempered metadynamics simulations precisely describe the characteristics of melatonin binding to specific sites in the membrane and reveal the role of cholesterol in free energy barrier crossing. A specific molecular torsional angle and the distance between melatonin and the center of the membrane along the normal to the membrane Z-axis have been considered as suitable reaction coordinates. Free energy barriers between two particular orientations of the molecular structure (folded and extended) have been found to be of about 18 kJ/mol for z-distances of about 1–2 nm. The ability of cholesterol to expel melatonin out of the internal regions of the membrane towards the interface and the external solvent is explained from a free energy perspective. The calculations reported here offer detailed free energy landscapes of melatonin embedded in model cell membranes and reveal microscopic information on its transition between free energy minima, including the location of relevant transition states, and provide clues on the role of cholesterol in the cellular absorption of small molecules.

Nasal Drug Delivery of Anticancer Drugs for the Treatment of Glioblastoma: Preclinical and Clinical Trials

Glioblastoma (GBM) is the most lethal form of brain tumor, being characterized by the rapid growth and invasion of the surrounding tissue. The current standard treatment for glioblastoma is surgery, followed by radiotherapy and concurrent chemotherapy, typically with temozolomide. Although extensive research has been carried out over the past years to develop a more effective therapeutic strategy for the treatment of GBM, efforts have not provided major improvements in terms of the overall survival of patients. Consequently, new therapeutic approaches are urgently needed. Overcoming the blood–brain barrier (BBB) is a major challenge in the development of therapies for central nervous system (CNS) disorders. In this context, the intranasal route of drug administration has been proposed as a non-invasive alternative route for directly targeting the CNS. This route of drug administration bypasses the BBB and reduces the systemic side effects. Recently, several formulations have been developed for further enhancing nose-to-brain transport, mainly with the use of nano-sized and nanostructured drug delivery systems. The focus of this review is to provide an overview of the strategies that have been developed for delivering anticancer compounds for the treatment of GBM while using nasal administration. In particular, the specific properties of nanomedicines proposed for nose-to-brain delivery will be critically evaluated. The preclinical and clinical data considered supporting the idea that nasal delivery of anticancer drugs may represent a breakthrough advancement in the fight against GBM.

Binding and dynamics of melatonin at the interface of phosphatidylcholine-cholesterol membranes

The characterization of interactions between melatonin, one main ingredient of medicines regulating sleeping rhythms, and basic components of cellular plasma membranes (phospholipids, cholesterol, metal ions and water) is very important to elucidate the main mechanisms for the introduction of melatonin into cells and also to identify its local structure and microscopic dynamics. Molecular dynamics simulations of melatonin inside mixtures of dimyristoylphosphatidylcholine and cholesterol in NaCl solution at physiological concentration have been performed at 303.15 K to systematically explore melatonin-cholesterol, melatonin-lipid and melatonin-water interactions. Properties such as the area per lipid and thickness of the membrane as well as selected radial distribution functions, binding free energies, angular distributions, atomic spectral densities and translational diffusion of melatonin are reported. The presence of cholesterol significantly affects the behavior of melatonin, which is mainly buried into the interfaces of membranes. Introducing cholesterol into the system helps melatonin change from folded to extended configurations more easily. Our results suggest that there exists a competition between the binding of melatonin to phospholipids and to cholesterol by means of hydrogen-bonds. Spectral densities of melatonin reported in this work, in overall good agreement with experimental data, revealed the participation of each atom of melatonin to its complete spectrum. Melatonin self-diffusion coefficients are of the order of 10-7 cm2/s and they significantly increase when cholesterol is addeed to the membrane.

Radioprotective effect of endogenous melatonin secretion associated with the circadian rhythm in irradiated rats

Purpose: We investigated the radioprotective effect of endogenous melatonin release at different times associated with the circadian rhythm on head and neck radiotherapy. Materials and methods: Two groups of animals were subjected daily to 8 Gy single fraction radiotherapy in the head and neck region from 5:00 to 6:00 (the morning group) or from 19:00 to 20:00 (the evening group). Corresponding untreated groups served as controls. Submandibular glands from rats sacrificed on the seventh day after irradiation were assessed biochemically and histopathologically. Melatonin, malondialdehyde and superoxide dismutase levels in blood collected immediately prior to irradiation were measured with rat-specific ELISA kits. Results: In irradiated rats, melatonin, malondialdehyde and superoxide dismutase levels were significantly higher in the evening group than in the morning group. In nonirradiated rats, melatonin and superoxide dismutase levels were significantly higher in the evening group than in the morning group. The areas of seromucous acinar cells were similar between the irradiated and nonirradiated evening groups, but the area was higher in the evening irradiated group than in the morning irradiated group. Conclusion: Consideration of endogenous melatonin secretion associated with the circadian rhythm may offer new therapeutic solutions for the complications of head and neck radiotherapy.

Melatonin for the management of sleep problems in children with neurodevelopmental disorders: a systematic review and meta-analysis

IMPORTANCE

Children with neurodevelopmental disorders have a higher prevalence of sleep disturbances. Currently there is variation in the use of melatonin; hence, an up-to-date systematic review is indicated to summarise the current available evidence.

OBJECTIVE

To determine the efficacy and safety of melatonin as therapy for sleep problems in children with neurodevelopmental disorders.

DATA SOURCES AND STUDY SELECTIONS

PubMed, Embase, the Cumulative Index to Nursing and Allied Health Literature and the Cochrane Central Register of Controlled Trials were searched from inception up to January 2018. Two reviewers performed data assessment and extraction. We assessed randomised controlled trials that compared melatonin with placebo or other intervention for the management of sleep disorders in children (<18 years) with neurodevelopmental disorders.

DATA EXTRACTION AND SYNTHESIS

We identified 3262 citations and included 13 studies in this meta-analysis.

MAIN OUTCOMES

Main outcomes included total sleep time, sleep onset latency, frequency of nocturnal awakenings and adverse events.

RESULTS

Thirteen randomised controlled trials (n=682) met the inclusion criteria. A meta-analysis of nine studies (n=541) showed that melatonin significantly improved total sleep time compared with placebo (mean difference (MD)=48.26 min, 95% CI 36.78 to 59.73, I²=31%). In 11 studies (n=581), sleep onset latency improved significantly with melatonin use (MD=-28.97, 95% CI -39.78 to -18.17). No difference was noted in the frequency of nocturnal awakenings (MD=-0.49, 95% CI -1.71 to 0.73). No medication-related serious adverse event was reported.

CONCLUSION

Melatonin appeared safe and effective in improving sleep in the studied children. The overall quality of the evidence is limited due to heterogeneity and inconsistency. Further research is needed.

Effects of cholesterol on the binding of the precursor neurotransmitter tryptophan to zwitterionic membranes

The characterization of the microscopical forces between the essential α-amino-acid tryptophan, precursor of the neurotransmitter serotonin and of the hormone melatonin, and the basic components of cell membranes and their environments (phospholipids, cholesterol, ionic species, and water) is of central importance to elucidate their local structure and dynamics as well as the mechanisms responsible for the access of tryptophan to the interior of the cell. We have performed nanosecond molecular dynamics simulations of tryptophan embedded in model zwitterionic bilayer membranes made by di-palmitoyl-phosphatidyl-choline and cholesterol inside aqueous sodium-chloride solution in order to systematically examine tryptophan-lipid, tryptophan-cholesterol, and tryptophan-water interactions under liquid-crystalline phase conditions. Microscopic properties such as the area per lipid, lipid thickness, radial distribution functions, hydrogen-bonding lengths, atomic spectral densities, and self-diffusion coefficients have been evaluated. Our results show that the presence of tryptophan significantly affects the structure and dynamics of the membrane. Tryptophan spends long periods of time at the water-membrane interface, and it plays a central role by bridging a few lipids and cholesterol chains by means of hydrogen-bonds. The computed spectral densities, in excellent agreement with experimental infrared and Raman data, revealed the participation of each atomic site of tryptophan to the complete spectrum of the molecule. Tryptophan self-diffusion coefficients have been found to be in between 10^-7 and 10^-6 cm²/s and strongly depending of the concentration of cholesterol in the system.

Shift work and cognitive impairment in later life - results of a cross-sectional pilot study testing the feasibility of a large-scale epidemiologic investigation

BACKGROUND

The effect of shift work on impairment of cognition in later life has not yet been sufficiently investigated. Therefore, we aimed at testing the feasibility of a large-scale epidemiologic study examining this putative association in a pilot study.

METHODS

Between January and April 2017, a cross-sectional study invited a random sample of 425 former and current employees of a German university hospital aged 55 years and older to undergo a cognitive test battery (including the Repeatable Battery for the Assessment of Neuropsychological Status, Trail Making Test, Letter-Number Span, and Vocabulary Test) and to complete a self-administered questionnaire on socio-demographic characteristics, chronotype, sleep, occupational history including shift work, and medical history. Fifty percent of the invitees were registered in the hospital's occupational records as currently working or having worked in a shift system. The feasibility of a large-scale study was evaluated by the response of the study sample and the completeness of data. In addition, we calculated the prevalence of shift work and cognitive impairment in the study population.

RESULTS

Seventy five subjects (18%) completed the questionnaire, of whom 47 (11% of the total sample) participated in cognitive testing. In all but four items assessed in the questionnaire, the proportion of missing data was below 10 %, suggesting that the quality of collected data can be considered as high. Eighty percent of the participants reported that they ever worked in a shift system, indicating selective participation by exposure to shift work. With respect to chronotype, the majority of the study subjects rated themselves as rather evening type, while a quarter considered themselves as definite morning type. All cognitive tests could be carried out completely. We observed slight difficulties in at least one of the cognitive tests in 17 participants (36%) while two participants (4%) showed more pronounced signs of cognitive impairment.

CONCLUSION

The present pilot study only partially supported the feasibility of the planned large-scale study. As response rates were low and depended on exposure to shift work, a better way of sampling and recruitment needs to be identified. The questionnaire and the test battery appear to be viable instruments.

Melatonin: A hypothesis for Kawasaki disease treatment

Kawasaki disease (KD) is the most common cause of acquired heart disease with unknown etiology among children in developed countries. Acute inflammation of the vasculature, genetic susceptibility and immunopathogenesis based on a transmittable and infectious origin, are the pathologic events involved in the early inflammatory etiology and progression of this disease. However, the exact causes of KD remain unknown. Current proposed recommendations include three therapy lines; firstly, an initial standard therapy with intravenous immunoglobulin (IVIG) followed by aspirin. Secondly, in cases of high risk of coronary lesions, the adjunctive therapy with corticosteroid is commonly considered. Thirdly, in KD patients refractory to the previous therapies, tumor necrosis factor (TNF-α) antagonists are being used to modulate pro-inflammatory cytokines. In view of this status quo, our starting hypothesis is that the ubiquitous and non-toxic neurohormone melatonin could be of critical importance in developing novel adjuvant therapies against KD, as it occurs with a plethora of other diseases. Considering its pleiotropic properties, particularly its antiinflammatory and immunoregulatory capacities, melatonin should be of great therapeutic interest for helping to control the main pathologic features of KD patients. In addition, this multifunctional indole has a safe pharmacological profile, enhancing the therapeutic activity of several drugs and reducing their possible side effects. Consequently, melatonińs actions to manage KD need to be tested in further clinical studies.

Melatonin Synergizes the Chemotherapeutic Effect of Cisplatin in Ovarian Cancer Cells Independently of MT1 Melatonin Receptors

BACKGROUND/AIM

Melatonin (MLT), through the interaction with membrane melatonin receptors MT1, can improve the effectiveness of cytostatic agents, including cisplatin (CP). The aim of this study was to examine the synergistic effect of MLT and CP in three cell lines: IOSE 364, SK-OV-3 and OVCAR-3, as well as to assess the role of MT1 receptors in this mechanism.

MATERIALS AND METHODS

Using the SRB assay we investigated the effect of different concentrations of CP and MLT on cell viability. Tests, using luzindole - MT1 inhibitor, allowed us to assess the potential involvement of MT1 in the mechanism of MLT action.

RESULTS

MLT at certain concentrations demonstrated a synergistic effect in combination with CP. The addition of luzindole did not affect the action of MLT in combination with CP.

CONCLUSION

In summary, the synergistic effect of MLT with CP seems to be independent of membrane MT1 receptors.

Melatonin as a Novel Interventional Candidate for Fragile X Syndrome with Autism Spectrum Disorder in Humans

Fragile X syndrome (FXS) is the most common monogenic form of autism spectrum disorder (ASD). FXS with ASD results from the loss of fragile X mental retardation (fmr) gene products, including fragile X mental retardation protein (FMRP), which triggers a variety of physiological and behavioral abnormalities. This disorder is also correlated with clock components underlying behavioral circadian rhythms and, thus, a mutation of the fmr gene can result in disturbed sleep patterns and altered circadian rhythms. As a result, FXS with ASD individuals may experience dysregulation of melatonin synthesis and alterations in melatonin-dependent signaling pathways that can impair vigilance, learning, and memory abilities, and may be linked to autistic behaviors such as abnormal anxiety responses. Although a wide variety of possible causes, symptoms, and clinical features of ASD have been studied, the correlation between altered circadian rhythms and FXS with ASD has yet to be extensively investigated. Recent studies have highlighted the impact of melatonin on the nervous, immune, and metabolic systems and, even though the utilization of melatonin for sleep dysfunctions in ASD has been considered in clinical research, future studies should investigate its neuroprotective role during the developmental period in individuals with ASD. Thus, the present review focuses on the regulatory circuits involved in the dysregulation of melatonin and disruptions in the circadian system in individuals with FXS with ASD. Additionally, the neuroprotective effects of melatonin intervention therapies, including improvements in neuroplasticity and physical capabilities, are discussed and the molecular mechanisms underlying this disorder are reviewed. The authors suggest that melatonin may be a useful treatment for FXS with ASD in terms of alleviating the adverse effects of variations in the circadian rhythm.

[Influence chronopharmacology therapy methionine (melaxen) on the dynamics of sleep disturbance, cognitive and emotional disorders, brain-derived neurotrophic factor (BDNF) in patients with cerebral stroke in the early and late recovery periods]

AIM

To study the efficacy of melaxen on the dynamics of sleep disturbance, cognitive and emotional disorders, BDNF and the level of secretion of melatonin (6-SOMT) in patients with stroke in the early and late recovery phase.

MATERIAL AND METHODS

One hundred and ten patients in the rehabilitation period of stroke (mean age of 58.4±6.4 years), including 60 patients in the early recovery phase (group 1) and 50 patients in the late phase (group 2), were studied. Patients received melaxen in dose of 3 mg/day for 3 months along with standard treatment. The efficacy of therapy was assessed by the dynamics of sleep disorders, emotional status, dynamics of serum BDNF levels, 6-SOMT concentration in the urine.

RESULTS AND CONCLUSION

The study has demonstrated the high efficacy of melaxen in the rehabilitation of patients in early and late recovery phase of stroke. The drug significantly increased the BDNF level that correlated with improved sleep, emotional status, quality of life of patients.

Beneficial Effects of Exogenous Melatonin in Acute Staphylococcus aureus and Escherichia coli Infection-Induced Inflammation and Associated Behavioral Response in Mice After Exposure to Short Photoperiod

The administration of melatonin during acute bacterial infection was evaluated in this study. Mice pre-exposed to normal photoperiodic (NP), short photoperiodic (SP), and long photoperiodic (LP) day lengths were infected separately with live Staphylococcus aureus (5 × 10⁶ cells/ml) or Escherichia coli (2.5 × 10⁷ colony-forming units/ml) and treated with melatonin (10 mg/kg body weight). Behavioral studies were performed before bacterial infection and after melatonin administration. In mice pre-exposed to SP, exogenous melatonin administration resulted in better clearance of bacteria from blood and behavioral improvement. Reduced glutathione content and superoxide dismutase activities were increased, with concomitant decrease in lipid peroxidation content and catalase activities in the liver, brain, and spleen after exogenous melatonin administration. The overproduction of tumor necrosis factor-α, interferon-γ, and interleukin-6 during acute bacterial infection in mice exposed to different photoperiods was probably regulated by the administration of exogenous melatonin, by reducing neutrophil recruitment to spleen, expression of inducible nitric oxide synthase and cyclooxygenase-2 in hypothalamus, and C-reactive protein in the serum, and was also associated with improved behavioral response. Photoperiodic variations in inflammatory and oxidative stress markers might be correlated to serum melatonin and corticosterone levels. This study suggests that the administration of melatonin during SP exposure is protective in infection-induced inflammation than NP and LP exposure.

Regulation of the nitric oxide oxidase activity of myeloperoxidase by pharmacological agents

The leukocyte-derived heme enzyme myeloperoxidase (MPO) is released extracellularly during inflammation and impairs nitric oxide (NO) bioavailability by directly oxidizing NO or producing NO-consuming substrate radicals. Here, structurally diverse pharmacological agents with activities as MPO substrates/inhibitors or antioxidants were screened for their effects on MPO NO oxidase activity in human plasma and physiological model systems containing endogenous MPO substrates/antioxidants (tyrosine, urate, ascorbate). Hydrazide-based irreversible/reversible MPO inhibitors (4-ABAH, isoniazid) or the sickle cell anaemia drug, hydroxyurea, all promoted MPO NO oxidase activity. This involved the capacity of NO to antagonize MPO inhibition by hydrazide-derived radicals and/or the ability of drug-derived radicals to stimulate MPO turnover thereby increasing NO consumption by MPO redox intermediates or NO-consuming radicals. In contrast, the mechanism-based irreversible MPO inhibitor 2-thioxanthine, potently inhibited MPO turnover and NO consumption. Although the phenolics acetaminophen and resveratrol initially increased MPO turnover and NO consumption, they limited the overall extent of NO loss by rapidly depleting H₂O₂ and promoting the formation of ascorbyl radicals, which inefficiently consume NO. The vitamin E analogue trolox inhibited MPO NO oxidase activity in ascorbate-depleted fluids by scavenging NO-consuming tyrosyl and urate radicals. Tempol and related nitroxides decreased NO consumption in ascorbate-replete fluids by scavenging MPO-derived ascorbyl radicals. Indoles or apocynin yielded marginal effects. Kinetic analyses rationalized differences in drug activities and identified criteria for the improved inhibition of MPO NO oxidase activity. This study reveals that widely used agents have important implications for MPO NO oxidase activity under physiological conditions, highlighting new pharmacological strategies for preserving NO bioavailability during inflammation.

Sleep, Melatonin, and the Menopausal Transition: What Are the Links?

The pineal hormone Melatonin plays an important role in the regulation of the circadian sleep/wake cycle, mood, and perhaps immune functions, carcinogensis and reproduction. The human circadian rhythm of melatonin release from the pineal gland is tightly synchronized with the habitual hours of sleep. Peri- and postmenopausal women often complain of difficulties initiating and/or maintaining sleep, with frequent nocturnal and early morning awakenings. In this review we discuss the pathophysiology of melatonin function as it relates to sleep disorders in menopausal women, highlighting the potential use of exogenous melatonin during the menopausal transition and beyond.

The Use of Melatonin by Children: Parents' Perspectives

STUDY OBJECTIVES

To explore the perceptions and experiences of parents whose children were using melatonin.

METHODS

A qualitative exploratory study was undertaken using face-to-face semi-structured interviews that were audio recorded and transcribed verbatim. Data was thematically analyzed via open coding and subsequent axial coding. Data collection continued until theoretical saturation occurred.

RESULTS

Eleven interviews with parents of children with a neurodevelopmental disorder were conducted. Each parent perceived melatonin as effective in alleviating their child's sleep disturbance, and in restoring family functioning after many years of hardship and stress. The perceived "naturalness" of melatonin was valued by participants, who tended to favor it over other medications prescribed for sleep. The cost of melatonin was also commented on by every participant; however, all perceived the benefits of melatonin for the child and the family to outweigh the cost burden. When discussing the future, some parents were unsure of whether their child would still be using melatonin; however, others were happy for their child to continue melatonin indefinitely. In addition, many parents expressed a desire for prescribers to have greater knowledge about melatonin, and to acknowledge the positive impact melatonin had had on their lives.

CONCLUSIONS

Parents perceive melatonin to be effective in alleviating their child's sleep disturbance and in improving their behavior, as well as restoring family functioning.

[Melatonin as an inducing factor for multiple sclerosis]

Melatonin is one of the most multifunctional regulators in the organism. It plays a key role in the control of nerve, endocrine, and immune systems. Due to hormone neuroprotective activity, the possibility is now discussed on its clinical usage in treating neurodegenerative diseases, including multiple sclerosis. At the same time, melatonin is an effective regulator of immune reactions, in part, the reactions toward autoantigens. In this respect, the subset ofT lymphocytes producing IL-17 (Th17) is of special interest. As the Th17 subset plays a key role iri multiple sclerosis pathogenesis, the immunomodulating hormone effects toward Th17, may, in theory, nullify its positive neuroprotective activity.

Melatonin-based pickering emulsion for skin's photoprotection

CONTEXT

Based on its antioxidant activity, melatonin was recently found to have a protection effect against photocarcinogenesis.

OBJECTIVE

This work aimed to develop an innovative sunscreen formulation based on the Pickering emulsions concept, stabilized by physical UV filters, modified starch and natural oils associated to melatonin as a key strategy for prevention against UV-induced skin damage.

MATERIALS AND METHODS

For this purpose, melatonin was incorporated in Pickering emulsions that were characterized using physicochemical, in vitro and in vivo testing. Physicochemical studies included physical and chemical stability by a thorough pharmaceutical control. The possible protective effects of melatonin against UV-induced cell damage in HaCaT cell lines were investigated in vitro. The safety assessment and the in vivo biological properties of the final formulations, including Human Repeat Insult Patch Test and sunscreen water resistance tests were also evaluated.

RESULTS AND DISCUSSION

These studies demonstrated that melatonin sunscreen Pickering emulsion was beneficial and presented a powerful protection against UVB-induced damage in HaCat cells, including inhibition of apoptosis. The inclusion of zinc oxide, titanium dioxide, green coffee oil and starch ensured a high SPF (50+) against UVA and UVB.

CONCLUSION

The combination of melatonin, multifunctional solid particles and green coffee oil, contributed to achieve a stable, effective and innovative sunscreen with a meaningful synergistic protection against oxidative stress.

Cytoprotective Effects of Melatonin Against Amitriptyline-Induced Toxicity in Isolated Rat Hepatocytes

PURPOSE

Amitriptyline, one of the commonly used tricyclic antidepressants, caused rare but severe hepatotoxicity in patients who received it continuously. Previous findings showed that the intermediate metabolites of amitriptyline produced by CYP450 are involved in hepatic injury. Melatonin is an antiaging and antioxidant hormone synthesized from pineal gland. The aim of present study was to evaluate the protective role of melatonin in an in vitro model of isolated rat hepatocytes.

METHODS

Markers such as cell viability, reactive oxygen species formation, lipid peroxidation, mitochondrial membrane potential, and hepatocytes glutathione content were evaluated every 60 minutes for 180 minutes.

RESULTS

Present results indicated that administration of 1mM of melatonin effectively reduced the cell death, ROS formation and lipid peroxidation, mitochondrial membrane potential collapse, and reduced cellular glutathione content caused by amitriptyline.

CONCLUSION

Our results indicated that melatonin is an effective antioxidant in preventing amitriptyline-induced hepatotoxicity. We recommend further in vivo animal and clinical trial studies on the hepatoprotective effects of melatonin in patients receiving amitriptyline.

[Sleep disorders and circadian rhythms in diseases of the cardiovascular system]

OBJECTIVE

To study disturbances of sleep and circadian rhythms in patients with cardiovascular diseases taking into account the level of melatonin secretion and to optimize a complex approach to their treatment.

MATERIALS AND METHODS

The study included patients with cardiovascular diseases with- (n=121) and without (n=105) cerebrovascular diseases (CVD). All patients received melaxen in dose 3 mg daily 30-40 min before sleep. Examination of patients included assessment of neurological status, psychometric scales, the definition of circadian rhythm of the heart and blood pressure, determination of 6-SOMT in daily urine.

RESULTS

Pathological changes in circadian rhythms affected sleep disturbances, emotional and cognitive disorders and were associated with a reduction in the level of 6-SOMT in the urine. These changes were most pronounced in patients with CVD and stroke. The inclusion of melaxen in the comprehensive regimen of treatment improved sleep, reduced mood disorders and normalized the circadian heart rate profile and blood pressure.

CONCLUSION

The data obtained allowed to consider melaxen as an effective tool in the complex therapy of patients with CVD.

Role of melatonin in traumatic brain injury and spinal cord injury

Brain and spinal cord are implicated in incidences of two of the most severe injuries of central nervous system (CNS). Traumatic brain injury (TBI) is a devastating neurological deficit involving primary and secondary injury cascades. The primary and secondary mechanisms include complex consequences of activation of proinflammatory cytokines, cerebral edema, upregulation of NF-κβ, disruption of blood-brain barrier (BBB), and oxidative stress. Spinal cord injury (SCI) includes primary and secondary injury cascades. Primary injury leads to secondary injury in which generation of free radicals and oxidative or nitrative damage play an important pathophysiological role. The indoleamine melatonin is a hormone secreted or synthesized by pineal gland in the brain which helps to regulate sleep and wake cycle. Melatonin has been shown to be a versatile hormone having antioxidative, antiapoptotic, neuroprotective, and anti-inflammatory properties. It has a special characteristic of crossing BBB. Melatonin has neuroprotective role in the injured part of the CNS after TBI and SCI. A number of studies have successfully shown its therapeutic value as a neuroprotective agent in the treatment of neurodegenerative diseases. Here in this review we have compiled the literature supporting consequences of CNS injuries, TBI and SCI, and the protective role of melatonin in it.

Effects of tryptophan-rich breakfast and light exposure during the daytime on melatonin secretion at night

Background

The purpose of the present study is to investigate effects of tryptophan intake and light exposure on melatonin secretion and sleep by modifying tryptophan ingestion at breakfast and light exposure during the daytime, and measuring sleep quality (by using actigraphy and the OSA sleep inventory) and melatonin secretion at night.

Methods

Thirty three male University students (mean ± SD age: 22 ± 3.1 years) completed the experiments lasting 5 days and 4 nights. The subjects were randomly divided into four groups: Poor*Dim (n = 10), meaning a tryptophan-poor breakfast (55 mg/meal) in the morning and dim light environment (<50 lx) during the daytime; Rich*Dim (n = 7), tryptophan-rich breakfast (476 mg/meal) and dim light environment; Poor*Bright (n = 9), tryptophan-poor breakfast and bright light environment (>5,000 lx); and Rich*Bright (n = 7), tryptophan-rich breakfast and bright light.

Results

Saliva melatonin concentrations on the fourth day were significantly lower than on the first day in the Poor*Dim group, whereas they were higher on the fourth day in the Rich*Bright group. Creatinine-adjusted melatonin in urine showed the same direction as saliva melatonin concentrations. These results indicate that the combination of a tryptophan-rich breakfast and bright light exposure during the daytime could promote melatonin secretion at night; further, the observations that the Rich*Bright group had higher melatonin concentrations than the Rich*Dim group, despite no significant differences being observed between the Poor*Dim and Rich*Dim groups nor the Poor*Bright and Rich*Bright groups, suggest that bright light exposure in the daytime is an important contributor to raised melatonin levels in the evening.

Conclusions

This study is the first to report the quantitative effects of changed tryptophan intake at breakfast combined with daytime light exposure on melatonin secretion and sleep quality. Evening saliva melatonin secretion changed significantly and indicated that a tryptophan-rich breakfast and bright light exposure during the daytime promoted melatonin secretion at this time.