Melatonin supplementation over different time periods until ageing modulates genotoxic parameters in mice

The Impact of Resveratrol and Melatonin on the Genome and Oxidative Status in Ageing Rats

BACKGROUND

Given the growing challenges posed by an ageing population, particularly in Western countries, we aimed to investigate the potential geroprotective effects of resveratrol and melatonin in ageing rats.

METHODS

The animals were treated with these two compounds starting at 3 months of age and continuing until 1 year or 2 years of age. Using a multibiomarker approach, we assessed DNA damage, telomere length, and the oxidative status in their urine, liver, and kidneys.

RESULTS

Despite employing this experimental approach, our results did not provide conclusive evidence of geroprotective effects across the evaluated organs. However, we observed sex-dependent differences in response to treatment.

CONCLUSIONS

Given the high potency of these two compounds, further research is warranted to explore their incorporation into daily routines as a strategy to mitigate ageing-related effects.

Melatonin in animal husbandry: functions and applications

Melatonin (N-acetyl-5-methoxytryptamine) is an essential small molecule with diverse biological functions. It plays several key roles, including regulating the secretion of reproductive hormones and the reproductive cycle, enhancing the functionality of reproductive organs, improving the quality of sperm and eggs, and mitigating oxidative stress in the reproductive system. Melatonin effectively inhibits and scavenges excess free radicals while activating the antioxidant enzyme system and reduces the production of inflammatory factors and alleviates tissue damage caused by inflammation by regulating inflammatory pathways. Additionally, melatonin contributes to repairing the intestinal barrier and regulating the gut microbiota, thereby reducing bacterial and toxin permeation. The use of melatonin as an endogenous hormone in animal husbandry has garnered considerable attention because of its positive effects on animal production performance, reproductive outcomes, stress adaptation, disease treatment, and environmental sustainability. This review explores the characteristics and biological functions of melatonin, along with its current applications in animal production. Our findings may serve as a reference for the use of melatonin in animal farming and future developmental directions.

Melatonin and Vascular Function

The indolamine hormone melatonin, also known as N-acetyl-5-methoxytrypamine, is frequently associated with circadian rhythm regulation. Light can suppress melatonin secretion, and photoperiod regulates melatonin levels by promoting its production and secretion at night in response to darkness. This hormone is becoming more and more understood for its functions as an immune-modulatory, anti-inflammatory, and antioxidant hormone. Melatonin may have a major effect on several diabetes-related disturbances, such as hormonal imbalances, oxidative stress, sleep disturbances, and mood disorders, according to recent research. This has raised interest in investigating the possible therapeutic advantages of melatonin in the treatment of diabetic complications. In addition, several studies have described that melatonin has been linked to the development of diabetes, cancer, Alzheimer's disease, immune system disorders, and heart diseases. In this review, we will highlight some of the functions of melatonin regarding vascular biology.

Melatonin as Modulator for Sulfur and Nitrogen Mustard-Induced Inflammation, Oxidative Stress and DNA Damage: Molecular Therapeutics

Sulfur and nitrogen mustards, bis(2-chloroethyl)sulfide and tertiary bis(2-chloroethyl) amines, respectively, are vesicant warfare agents with alkylating activity. Moreover, oxidative/nitrosative stress, inflammatory response induction, metalloproteinases activation, DNA damage or calcium disruption are some of the toxicological mechanisms of sulfur and nitrogen mustard-induced injury that affects the cell integrity and function. In this review, we not only propose melatonin as a therapeutic option in order to counteract and modulate several pathways involved in physiopathological mechanisms activated after exposure to mustards, but also for the first time, we predict whether metabolites of melatonin, cyclic-3-hydroxymelatonin, N1-acetyl-N2-formyl-5-methoxykynuramine, and N1-acetyl-5-methoxykynuramine could be capable of exerting a scavenger action and neutralize the toxic damage induced by these blister agents. NLRP3 inflammasome is activated in response to a wide variety of infectious stimuli or cellular stressors, however, although the precise mechanisms leading to activation are not known, mustards are postulated as activators. In this regard, melatonin, through its anti-inflammatory action and NLRP3 inflammasome modulation could exert a protective effect in the pathophysiology and management of sulfur and nitrogen mustard-induced injury. The ability of melatonin to attenuate sulfur and nitrogen mustard-induced toxicity and its high safety profile make melatonin a suitable molecule to be a part of medical countermeasures against blister agents poisoning in the near future.

Human Variation in DNA Repair, Immune Function, and Cancer Risk

DNA damage constantly threatens genome integrity, and DNA repair deficiency is associated with increased cancer risk. An intuitive and widely accepted explanation for this relationship is that unrepaired DNA damage leads to carcinogenesis due to the accumulation of mutations in somatic cells. But DNA repair also plays key roles in the function of immune cells, and immunodeficiency is an important risk factor for many cancers. Thus, it is possible that emerging links between inter-individual variation in DNA repair capacity and cancer risk are driven, at least in part, by variation in immune function, but this idea is underexplored. In this review we present an overview of the current understanding of the links between cancer risk and both inter-individual variation in DNA repair capacity and inter-individual variation in immune function. We discuss factors that play a role in both types of variability, including age, lifestyle, and environmental exposures. In conclusion, we propose a research paradigm that incorporates functional studies of both genome integrity and the immune system to predict cancer risk and lay the groundwork for personalized prevention.

Melatonin as an Anti-Aging Therapy for Age-Related Cardiovascular and Neurodegenerative Diseases

The concept of “aging” is defined as the set of gradual and progressive changes in an organism that leads to an increased risk of weakness, disease, and death. This process may occur at the cellular and organ level, as well as in the entire organism of any living being. During aging, there is a decrease in biological functions and in the ability to adapt to metabolic stress. General effects of aging include mitochondrial, cellular, and organic dysfunction, immune impairment or inflammaging, oxidative stress, cognitive and cardiovascular alterations, among others. Therefore, one of the main harmful consequences of aging is the development and progression of multiple diseases related to these processes, especially at the cardiovascular and central nervous system levels. Both cardiovascular and neurodegenerative pathologies are highly disabling and, in many cases, lethal. In this context, melatonin, an endogenous compound naturally synthesized not only by the pineal gland but also by many cell types, may have a key role in the modulation of multiple mechanisms associated with aging. Additionally, this indoleamine is also a therapeutic agent, which may be administered exogenously with a high degree of safety. For this reason, melatonin could become an attractive and low-cost alternative for slowing the processes of aging and its associated diseases, including cardiovascular and neurodegenerative disorders.

Melatonin Attenuates Inflammation, Oxidative Stress, and DNA Damage in Mice with Nonalcoholic Steatohepatitis Induced by a Methionine- and Choline-Deficient Diet

Nonalcoholic steatohepatitis (NASH) is a disease with a high incidence worldwide, but its diagnosis and treatment are poorly managed. In this study, NASH pathophysiology and DNA damage biomarkers were investigated in mice with NASH treated and untreated with melatonin (MLT). C57BL/6 mice were fed a methionine- and choline-deficient (MCD) diet for 4 weeks to develop NASH. Melatonin was administered at 20 mg/kg during the last 2 weeks. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were measured, and hepatic tissue was dissected for histological analysis, evaluation of lipoperoxidation, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as nuclear factor-erythroid 2 (Nrf2), tumor necrosis factor alpha (TNF-α), inducible nitric oxide synthase (iNOS), and transforming growth factor beta (TGF-β) expression by immunohistochemistry. DNA damage was evaluated using Comet assay, while a micronucleus test in bone marrow was performed to assess the genomic instability associated with the disease. Melatonin decreased AST and ALT, liver inflammatory processes, balloonization, and fibrosis in mice with NASH, decreasing TNF-α, iNOS, and TGF-β, as well as oxidative stress, shown by reducing lipoperoxidation and intensifying Nrf2 expression. The SOD and GPx activities were increased, while CAT was decreased by treatment with MLT. Although the micronucleus frequency was not increased in mice with NASH, a protective effect on DNA was observed with MLT treatment in blood and liver tissues using Comet assay. As conclusions, MLT slows down the progression of NASH, reducing hepatic oxidative stress and inflammatory processes, inhibiting DNA damage via anti-inflammatory and antioxidant actions.

Long-term effects of melatonin and resveratrol on aging rats: A multi-biomarker approach

Aging-related impaired body structure and functions may be, at least partially, caused by elevated oxidative stress. Melatonin (MEL) and resveratrol (RSV) may act as antioxidant and anti-aging compounds, but these actions in experimental animals and humans are controversial. Herein, a rat model of aging was used to study the long-term sex-related effects of MEL and RSV treatment on body mass and blood/plasma parameters of DNA damage, oxidative status (glutathione and malondialdehyde levels), and concentrations of sex hormones. Starting from the age of 3mo, for the next 9mo or 21mo male and female Wistar rats (n = 4-7 per group) were given water to drink (controls) or 0.1 % ethanol in water (vehicle), or MEL or RSV (each 10 mg/L vehicle). DNA damage in whole blood cells was tested by comet assay, whereas in plasma, glutathione, malondialdehyde, and sex hormones were determined by established methods. Using statistical analysis of data by ANOVA/Scheffe post hoc, we observed a similar sex- and aging-dependent rise of body mass in both sexes and drop of plasma testosterone in control and vehicle-treated male rats, whose pattern remained unaffected by MEL and RSV treatment. Compared with controls, all other parameters remained largely unchanged in aging and differently treated male and female rats. We concluded that the sex- and aging-related pattern of growth and various blood parameters in rats were not affected by the long-term treatment with MEL and RSV at the estimated daily doses (300-400 μg/kg b.m.) that exceed usual moderate consumption in humans.