Immunoregulatory properties of melatonin in the humoral immune system: A narrative review.

Melatonin is the major product both synthesized and secreted by the pineal gland during the night period and it is the principal chronobiotic hormone that regulates the circadian rhythms and seasonal changes in vertebrate biology. Moreover, melatonin shows both a broad distribution along the phylogenetically distant organisms and a high functional versatility. At the present time, a significant amount of experimental evidence has been reported in scientific literature and has clearly shown a functional relationship between the endocrine, nervous, and immune systems. The biochemistry basis of the functional communication between these systems is the utilization of a common chemicals signals. In this framework, at present melatonin is considered to be a relevant member of the so-called neuro-endocrine-immunological network. Thus, both in vivo and in vitro investigations conducted in both experimental animals and humans, have clearly documented that melatonin has an important immunomodulatory role. However, most of the published results refer to information on T lymphocytes, i.e., cell-mediated immunity. On the contrary, fewer studies have been carried out on B lymphocytes, the cells responsible for the so-called humoral immunity. In this review, we have focused on the biological role of melatonin in the humoral immunity. More precisely, we report the actions of melatonin on B lymphocytes biology and on the production of different types of antibodies.

Assessing the Predictive Factors for Bleeding in Esophageal Variceal Disease: A Systematic Review.

Esophageal varices, dilated submucosal distal esophageal veins, are a common source of upper gastrointestinal bleeding in patients with portal hypertension. This review aims to comprehensively assess predictive factors for both the first occurrence and subsequent risk of esophageal variceal bleeding. A systematic search was conducted in PubMed/MEDLINE (Medical Literature Analysis and Retrieval System Online) and Cochrane databases. A total of 33 studies were selected using rigorous inclusion and exclusion criteria. The risk of bias was assessed using the Newcastle-Ottawa Scale. Several predictive factors were identified for esophageal variceal bleeding, including the Child-Pugh score, Fibrosis Index, specific endoscopic findings, ultrasound parameters, portal vein diameter, presence and size of collaterals, CT scan findings, ascites, platelet counts, coagulation parameters, albumin levels, Von Willebrand Factor, bilirubin levels, diabetes mellitus, and the use of b-blocking agents in primary prophylaxis. The findings of this systematic review shed light on multiple potential predictive factors for esophageal variceal bleeding. Endoscopic findings were found to be reliable predictors. Additionally, ultrasound parameters showed associations with bleeding risk. This systematic review identifies multiple potential predictive factors for esophageal variceal bleeding in patients with portal hypertension. While certain factors exhibit strong predictive capabilities, further research is needed to refine and validate these findings, considering potential limitations and biases. This study serves as a critical resource for bridging knowledge gaps in this field.

Melatonin as a potential therapeutic agent in psychiatric illness.

The aim of this review was to summarize the potential use of melatonin in the treatment of mental disorders, specifically bipolar disorders, depression, and schizophrenia. To date, melatonin has been most commonly used in psychiatry because of its hypnotic, rhythm resynchronizing, and antioxidant actions. Here, we examine other properties of the melatonin including its anti-inflammatory, antinociceptive, anxiolytic, and drug detoxification actions as well as its protective effects against neural loss. The brain is an intricate sensory and motor organ which receives information from both the external and internal environments. It transduces information into complex chemical and electrical signals which are transmitted throughout the central nervous system (CNS) and the organism. The pathogenesis of mental disorders remains ambiguous and neuroinflammation has been proposed as a causative agent. We consider the potential contributions of melatonin as therapeutic agent in CNS and during neuroinflammation in mental disorders.

Chronic melatonin treatment prevents age-dependent cardiac mitochondrial dysfunction in senescence-accelerated mice.

Heart mitochondria from female senescence-accelerated (SAMP8) and senescence-resistant (SAMR1) mice of 5 or 10 months of age, were studied. Mitochondrial oxidative stress was determined by measuring the levels of lipid peroxidation, glutathione and glutathione disulfide and glutathione peroxidase and reductase activities. Mitochondrial function was assessed by measuring the activity of the respiratory chain complexes and ATP content. The results show that the age-dependent mitochondrial oxidative damage in the heart of SAMP8 mice was accompanied by a reduction in the electron transport chain complex activities and in ATP levels. Chronic melatonin administration between 1 and 10 months of age normalized the redox and the bioenergetic status of the mitochondria and increased ATP levels. The results support the presence of significant mitochondrial oxidative stress in SAM mice at 10 months of age, and they suggest a beneficial effect of chronic pharmacological intervention with melatonin, which reduces the deteriorative and functional oxidative changes in cardiac mitochondria with age.

Melatonin and lipid uptake by murine fibroblasts: clinical implications.

The current study was undertaken to uncover the role of melatonin in lipid metabolism in the murine fibroblasts. The results show melatonin in vitro enhances lipid accumulation and lipid droplet formation in this cell line. Using oil red O staining, it was found that when oleic acid was present in the culture media, melatonin at doses of 0.1-2mM, significantly increased the lipid concentrations in the cells. However, low levels of melatonin, with or without oleic acid, did not influence lipid metabolism in the cultured fibroblasts. When a non-specific melatonin receptor antagonist, luzindole 10 microM was co-incubated with 1mM melatonin, the stimulatory effects of melatonin on lipid accumulation in these cells was significantly reduced. It appears that the effects of melatonin on lipid metabolism in murine fibroblasts is mediated by melatonin membrane receptors.

Melatonin present in beer contributes to increase the levels of melatonin and antioxidant capacity of the human serum.

BACKGROUND & AIM: Melatonin is a molecule with antioxidative properties including direct free radical scavenging and indirect stimulatory actions on a variety of antioxidative enzymes which further promote its ability to reduce the toxicity of radicals and their associated reactants. Beer is an integral element of the diet of numerous people and is rich in antioxidants. We analyzed if melatonin is present in beer and if so, at what concentration. It further determines whether the moderate consumption of beer has an effect on the total antioxidant status (TAS) of human serum. METHODS: We analyzed 18 brands of beer with different percentage of alcohol content in order to determine the concentration of melatonin. Serum samples were collected from 7 healthy volunteers. These samples were used to measure melatonin and TAS on basal conditions and after drinking beer. RESULTS: Showed that all the beer analyzed did indeed contain melatonin and the more they have got, the greater was its degree of alcohol. Both melatonin and TAS in human serum increased after drinking beer. CONCLUSIONS: Melatonin present in the beer does contribute to the total antioxidative capability of human serum and moderate beer consumption can protect organism from overall oxidative stress.

The role of melatonin in the immuno-neuro-psychology of mental disorders.

Melatonin (N-acetyl-5-methoxytryptamine) is a molecule known to be produced in multiple cells and organs. It acts at the level of the biological clock, the suprachiasmatic nuclei, to modulate their activity, thereby influencing circadian rhythms, and also sleep processes. The clinical application of melatonin in the treatment of human mental disorders is still in its infancy. Until now, melatonin only has been used in psychiatry because of its hypnotic, resynchronizing and antioxidant actions. In this review, we hypothesized that melatonin might play an important role as an adjuvant therapy, in mental disturbances, due to other properties including its anti-inflammatory, antinociceptive, anxiolytic, drug detoxification properties, protective actions against osteoporosis, etc. Complex interactions occur between the brain and the immune system and currently is accepted that psychological and psychiatric illness can compromise immune and hormonal functions. Altered psychological states often influence the susceptibility of an individual to illness or modify the course of the illness and its prognosis. The present review discusses on the advantages of the co-treatment with melatonin and recent patents in three major psychiatric disorders: depression, bipolar syndrome and schizophrenia. The findings suggest new vistas in both the pathophysiology and the pharmacology of mental disorders.