Melatonin Antioxidative Defense: Therapeutical Implications for Aging and Neurodegenerative Processes

Exploring the Neuroprotective Effects of Rufinamide in a Streptozotocin-Induced Dementia Model

Due to the complex pathophysiology of AD (Alzheimer's Disease), there are currently no effective clinical treatments available, except for acetylcholinesterase inhibitors. However, CREB (cyclic AMP-responsive element binding protein) has been identified as the critical factor for the transcription in memory formation. Understanding the effect of potential drugs on the CREB pathway could lead to the development of new therapeutic molecules. Rufinamide has shown promise in improving memory in animal models, and these effects may be associated with modulation of the CREB pathway, however, this has not been previously reported. Thus, the present study aimed to determine the involvement of the CREB pathway in the cognitive improvement effects of rufinamide in STZ (streptozotocin) induced mouse model of dementia. Administration of STZ [3 mg/kg, i.c.v. (intracerebroventricular) bilaterally] significantly impaired cognitive performance in step-down passive avoidance and Morris water maze tests in animals, reduced brain endogenous antioxidant levels (GSH, superoxide dismutase, and catalase), and increased marker of brain oxidative stress [TBARS (thiobarbituric acid reactive substances)] and inflammation [IL-1β (Interleukin-1 beta), IL-6 (Interleukin-6), TNF-α (Tumor necrosis factor alpha) and NF-κB (Nuclear factor kappa B)], along with neurodegeneration. These effects were markedly reversed by rufinamide (50 and 100 mg/kg) when administered to STZ animals. However, the pre-treatment with the CREB inhibitor (666-15) in STZ and rufinamide-administered animals neutralized the beneficial influence of rufinamide. Our data suggest that rufinamide, acting via CREB signaling, reduced oxidative stress and inflammatory markers while elevating anti-oxidant levels. Our study has established that rufinamide may act through CREB signaling in an investigational AD model, which could be crucial for developing new treatments beneficial in progressive neurological disorders.

The role of sirtuin 1 in ageing and neurodegenerative disease: A molecular perspective

Sirtuin 1 (SIRT1), an NAD+-dependent deacetylase, has emerged as a key regulator of cellular processes linked to ageing and neurodegeneration. SIRT1 modulates various signalling pathways, including those involved in autophagy, oxidative stress, and mitochondrial function, which are critical in the pathogenesis of neurodegenerative diseases. This review explores the therapeutic potential of SIRT1 in several neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and Amyotrophic Lateral Sclerosis (ALS). Preclinical studies have demonstrated that SIRT1 activators, such as resveratrol, SRT1720, and SRT2104, can alleviate disease symptoms by reducing oxidative stress, enhancing autophagic flux, and promoting neuronal survival. Ongoing clinical trials are evaluating the efficacy of these SIRT1 activators, providing hope for future therapeutic strategies targeting SIRT1 in neurodegenerative diseases. This review explores the role of SIRT1 in ageing and neurodegenerative diseases, with a particular focus on its molecular mechanisms, therapeutic potential, and clinical applications.

Protective Activity of Melatonin Combinations and Melatonin-Based Hybrid Molecules in Neurodegenerative Diseases

The identification of protective agents for the treatment of neurodegenerative diseases is the mainstay therapeutic goal to modify the disease course and arrest the irreversible disability progression. Pharmacological therapies synergistically targeting multiple pathogenic pathways, including oxidative stress, mitochondrial dysfunction, and inflammation, are prime candidates for neuroprotection. Combination or synergistic therapy with melatonin, whose decline correlates with altered sleep/wake cycle and impaired glymphatic "waste clearance" system in neurodegenerative diseases, has a great therapeutic potential to treat inflammatory neurodegenerative states. Despite the protective outcomes observed in preclinical studies, mild or poor outcomes were observed in clinical settings, suggesting that melatonin combinations promoting synergistic actions at appropriate doses might be more suitable to treat multifactorial neurodegenerative disorders. In this review, we first summarize the key melatonin actions and pathways contributing to cell protection and its therapeutic implication in Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). We remark the major controversies in the field, mostly generated by the lack of a common consensus for the optimal dosing, molecular targets, and toxicity. Then, we review the literature investigating the efficacy of melatonin combinations with approved or investigational neuroprotective agents and of melatonin-containing hybrid molecules, both in vitro and in animal models of AD, PD, and MS, as well as the efficacy of add-on melatonin in clinical settings. We highlight the rationale for such melatonin combinations with a focus on the comparison with single-agent treatment and on the assays in which an additive or a synergistic effect has been achieved. We conclude that a better characterization of the mechanisms underlying such melatonin synergistic actions under neuroinflammation at appropriate doses needs to be tackled to advance successful clinical translation of neuroprotective melatonin combination therapies or melatonin-based hybrid molecules.

Evaluating the Protective Effects of Melatonin Against Chronic Iron Administration in Male Wistar Rats: a Comparative Analysis of Affective, Cognitive, and Oxidative Stress with EDTA Chelator

Iron is the dominant metal in the brain and is distributed widely. However, it can lead to various neuropathological and neurobehavioral abnormalities as well as oxidative stress. On the other hand, melatonin, a pineal hormone, is known for its neuroprotective properties, as well as its ability to act as a natural chelator against oxidative stress. It has also been used as an antidepressant and anxiolytic. The study investigated the potential of melatonin and EDTA treatment to prevent anxiety, depressive behavior, and memory impairment in male rats induced by chronic iron administration, and its connection to oxidative stress regulation in the hippocampus and prefrontal cortex. The rats were divided into six groups and intraperitoneally injected for 8 weeks with NaCl solution (control), iron sulfate (1 mg/kg), melatonin (4 mg/kg), EDTA (4 mg/kg), 1 mg/kg of iron + 4 mg/kg of melatonin, or 1 mg/kg of iron + 4 mg/kg of EDTA. In this study, we performed a neurobehavioral assessment and biochemical determinations of oxidative stress levels in the hippocampus and prefrontal cortex of each animal. The results indicate that chronic exposure to iron sulfate induced anxiety-like depressive behavior, and cognitive impairment also increased the levels of lipid peroxidation and nitric oxide, and reduced the activity of catalase in the hippocampus and prefrontal cortex in male Wistar rats, suggesting the induction of oxidative stress. In contrast, these alterations were reversed by melatonin better than EDTA. The results of this study show that melatonin protects against the neurobehavioral changes caused by iron, which may be associated with decreasing oxidative stress in the hippocampus and prefrontal cortex.

Melatonin effects on oxidative stress and on TLR4/NF-kβ inflammatory pathway in the right ventricle of rats with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterised by an increase in mean pulmonary arterial pressure and a compromised the right ventricle (RV), together with progression to heart failure and premature death. Studies have evaluated the role of melatonin as a promising therapeutic strategy for PAH. The objective of this study was to evaluate melatonin's effects on oxidative stress and on the TLR4/NF-kβ inflammatory pathway in the RV of rats with PAH. Male Wistar rats were divided into the following groups: control, monocrotaline (MCT), and monocrotaline plus melatonin groups. These two last groups received one intraperitoneal injection of MCT (60 mg/kg) on the first day of experimental protocol. The monocrotaline plus melatonin group received 10 mg/kg/day of melatonin by gavage for 21 days. Echocardiographic analysis was performed, and the RV was collected for morphometric analysis oxidative stress and molecular evaluations. The main findings of the present study were that melatonin administration attenuated the reduction in RV function that was induced by monocrotaline, as assessed by TAPSE. In addition, melatonin prevented RV diastolic area reduction caused by PAH. Furthermore, animals treated with melatonin did not show an increase in ROS levels or in NF-kβ expression. In addition, the monocrotaline plus melatonin group showed a reduction in TLR4 expression when compared with control and monocrotaline groups. To our knowledge, this is the first study demonstrating a positive effect of melatonin on the TLR4/NF-kβ pathway in the RV of rats with PAH. In this sense, this study makes it possible to think of melatonin as a possible ally in mitigating RV alterations caused by PAH.

Cartilage defect repair in a rat model via a nanocomposite hydrogel loaded with melatonin-loaded gelatin nanofibers and menstrual blood stem cells: an in vitro and in vivo study

Cartilage damage caused by injuries or degenerative diseases remains a major challenge in the field of regenerative medicine. In this study, we developed a composite hydrogel system for the delivery of melatonin and menstrual blood stem cells (MenSCs) to treat a rat model of cartilage defect. The composite delivery system was produced by incorporation of melatonin into the gelatin fibers and dispersing these fibers into calcium alginate hydrogels. Various characterization methods including cell viability assay, microstructure studies, degradation rate measurement, drug release, anti-inflammatory assay, and radical scavenging assay were used to characterize the hydrogel system. MenSCs were encapsulated within the nanocomposite hydrogel and implanted into a rat model of full-thickness cartilage defect. A 1.3 mm diameter drilled in the femoral trochlea and used for the in vivo study. Results showed that the healing potential of nanocomposite hydrogels containing melatonin and MenSCs was significantly higher than polymer-only hydrogels. Our study introduces a novel composite hydrogel system, combining melatonin and MenSCs, demonstrating enhanced cartilage repair efficacy, offering a promising avenue for regenerative medicine.

Protective efficacy of ramelteon on methotrexate-induced DNA damage

Ramelteon (RMLT) is a melatonin receptor agonist that it has antioxidative and anti-inflammatory effects associated with DNA damage through different mechanisms of action. In this regard, we investigated the potential usefulness of RMLT as a protective agent against methotrexate (MTX)-induced DNA damage. Four groups were constituted from 32 Wistar albino rats: Negative control, RMLT, MTX, and MTX + RMLT. Twenty mg/kg MTX (i.p., single dose) and RMLT 10 mg/kg (oral, 7 days) was administered. Comet assay was used and the parameter %TailDNA was used to detect DNA damage. %TailDNA was 4.90 ± 0.19 in the control group, 7.85 ± 0.33 in the MTX group, 5.49 ± 0.24 in the RMLT group, and 5.86 ± 0.23 in the MTX + RMLT group. While there was a significant increase in DNA damage in the MTX-treated group compared to the control group, there was a significant reduction in DNA damage in the MTX + RMLT group, compared to the MTX group (p < 0.001). In conclusion, it was observed that combined treatment with RMLT significantly reduced MTX-induced DNA damage.

Oligosaccharides from black ginseng innovatively prepared by low-temperature steam-heating process ameliorate cognitive impairment in Alzheimer's disease mice via the Keap-1/Nrf2 pathway

BACKGROUND

Our objective in this study was to evaluate the effectiveness of oligosaccharides extracted from black ginseng (OSBG), innovatively prepared by a low-temperature steam-heating process, in the improvement of learning and memory impairment in mice, as well as the mechanism(s).

RESULTS

Eight carbohydrates involving isomaltose and maltotetraose were detected in black gensing; monosaccharide residues including mannose and rhamnose were also discovered. OSBG-treated mice showed significant amelioration in recognition and spatial memory deficits compared to the scopolamine group. OSBG could decrease acetylcholinesterase activity in a tissue-dependent fashion but not in a dose-dependent manner. Furthermore, in contrast, OSBG administration resulted in significant upregulation superoxide dismutase, glutathione, glutathione peroxidase (GPx), and Kelch-like ECH-associated protein 1, downregulation of malondialdehyde and nuclear factor erythroid 2-related factor 2 in the tissues. Finally, at the genus level, we observed that the OSBG interventions increased the relative abundance of probiotics (e.g., Barnesiella, Staphylococcus, Clostridium_XlVb) and decreased pernicious bacteria such as Eisenbergiella and Intestinimonas, compared to the Alzheimer's disease mouse model group. Herein, our results demonstrate that OSBG restores the composition of the scopolamine-induced intestinal microbiota in mice, providing homeostasis of gut microbiota and providing evidence for microbiota-regulated therapeutic potential.

CONCLUSION

Our results showed for the first time a clear role for OSBG in improving scopolamine-induced memory impairment by inhibiting cholinergic dysfunction in a tissue-dependent manner. Additionally, OSBG administration relieved oxidative stress by activating the Keap-1/Nrf2 pathway and modulating the gut microbiota. Collectively, OSBG may be a promising target for neuroprotective antioxidants for improving memory and cognition in Alzheimer's disease patients. © 2024 Society of Chemical Industry.

Innovative approaches to Alzheimer's therapy: Harnessing the power of heterocycles, oxidative stress management, and nanomaterial drug delivery system

Alzheimer's disease (AD) presents a complex pathology involving amyloidogenic proteolysis, neuroinflammation, mitochondrial dysfunction, and cholinergic deficits. Oxidative stress exacerbates AD progression through pathways like macromolecular peroxidation, mitochondrial dysfunction, and metal ion redox potential alteration linked to amyloid-beta (Aβ). Despite limited approved medications, heterocyclic compounds have emerged as promising candidates in AD drug discovery. This review highlights recent advancements in synthetic heterocyclic compounds targeting oxidative stress, mitochondrial dysfunction, and neuroinflammation in AD. Additionally, it explores the potential of nanomaterial-based drug delivery systems to overcome challenges in AD treatment. Nanoparticles with heterocyclic scaffolds, like polysorbate 80-coated PLGA and Resveratrol-loaded nano-selenium, show improved brain transport and efficacy. Micellar CAPE and Melatonin-loaded nano-capsules exhibit enhanced antioxidant properties, while a tetra hydroacridine derivative (CHDA) combined with nano-radiogold particles demonstrates promising acetylcholinesterase inhibition without toxicity. This comprehensive review underscores the potential of nanotechnology-driven drug delivery for optimizing the therapeutic outcomes of novel synthetic heterocyclic compounds in AD management. Furthermore, the inclusion of various promising heterocyclic compounds with detailed ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) data provides valuable insights for planning the development of novel drug delivery treatments for AD.

Modulation of neural circuits by melatonin in neurodegenerative and neuropsychiatric disorders

Neurodegenerative and neuropsychiatric disorders are two broad categories of neurological disorders characterized by progressive impairments in movement and cognitive functions within the central and peripheral nervous systems, and have emerged as a significant cause of mortality. Oxidative stress, neuroinflammation, and neurotransmitter imbalances are recognized as prominent pathogenic factors contributing to cognitive deficits and neurobehavioral anomalies. Consequently, preventing neurodegenerative and neuropsychiatric diseases has surfaced as a pivotal challenge in contemporary public health. This review explores the investigation of neurodegenerative and neuropsychiatric disorders using both synthetic and natural bioactive compounds. A central focus lies on melatonin, a neuroregulatory hormone secreted by the pineal gland in response to light-dark cycles. Melatonin, an amphiphilic molecule, assumes multifaceted roles, including scavenging free radicals, modulating energy metabolism, and synchronizing circadian rhythms. Noteworthy for its robust antioxidant and antiapoptotic properties, melatonin exhibits diverse neuroprotective effects. The inherent attributes of melatonin position it as a potential key player in the pathophysiology of neurological disorders. Preclinical and clinical studies have demonstrated melatonin's efficacy in alleviating neuropathological symptoms across neurodegenerative and neuropsychiatric conditions (depression, schizophrenia, bipolar disorder, and autism spectrum disorder). The documented neuroprotective prowess of melatonin introduces novel therapeutic avenues for addressing neurodegenerative and psychiatric disorders. This comprehensive review encompasses many of melatonin's applications in treating diverse brain disorders. Despite the strides made, realizing melatonin's full neuroprotective potential necessitates further rigorous clinical investigations. By unravelling the extended neuroprotective benefits of melatonin, future studies promise to deepen our understanding and augment the therapeutic implications against neurological deficits.

Melatonin Ameliorates Post-Stroke Cognitive Impairment in Mice by Inhibiting Excessive Mitophagy

Post-stroke cognitive impairment (PSCI) remains the most common consequence of ischemic stroke. In this study, we aimed to investigate the role and mechanisms of melatonin (MT) in improving cognitive dysfunction in stroke mice. We used CoCl2-induced hypoxia-injured SH-SY5Y cells as a cellular model of stroke and photothrombotic-induced ischemic stroke mice as an animal model. We found that the stroke-induced upregulation of mitophagy, apoptosis, and neuronal synaptic plasticity was impaired both in vivo and in vitro. The results of the novel object recognition test and Y-maze showed significant cognitive deficits in the stroke mice, and Nissl staining showed a loss of neurons in the stroke mice. In contrast, MT inhibited excessive mitophagy both in vivo and in vitro and decreased the levels of mitophagy proteins PINK1 and Parkin, and immunofluorescence staining showed reduced co-localization of Tom20 and LC3. A significant inhibition of mitophagy levels could be directly observed under transmission electron microscopy. Furthermore, behavioral experiments and Nissl staining showed that MT ameliorated cognitive deficits and reduced neuronal loss in mice following a stroke. Our results demonstrated that MT inhibits excessive mitophagy and improves PSCI. These findings highlight the potential of MT as a preventive drug for PSCI, offering promising therapeutic implications.

The Vital Role of Melatonin and Its Metabolites in the Neuroprotection and Retardation of Brain Aging

While primarily produced in the pineal gland, melatonin's influence goes beyond its well-known role in regulating sleep, nighttime metabolism, and circadian rhythms, in the field of chronobiology. A plethora of new data demonstrates melatonin to be a very powerful molecule, being a potent ROS/RNS scavenger with anti-inflammatory, immunoregulatory, and oncostatic properties. Melatonin and its metabolites exert multiple beneficial effects in cutaneous and systemic aging. This review is focused on the neuroprotective role of melatonin during aging. Melatonin has an anti-aging capacity, retarding the rate of healthy brain aging and the development of age-related neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, amyotrophic lateral sclerosis, etc. Melatonin, as well as its metabolites, N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) and N1-acetyl-5-methoxykynuramine (AMK), can reduce oxidative brain damage by shielding mitochondria from dysfunction during the aging process. Melatonin could also be implicated in the treatment of neurodegenerative conditions, by modifying their characteristic low-grade neuroinflammation. It can either prevent the initiation of inflammatory responses or attenuate the ongoing inflammation. Drawing on the current knowledge, this review discusses the potential benefits of melatonin supplementation in preventing and managing cognitive impairment and neurodegenerative diseases.

Melatonin in energy control: Circadian time-giver and homeostatic monitor

Melatonin is a neurohormone synthesized from dietary tryptophan in various organs, including the pineal gland and the retina. In the pineal gland, melatonin is produced at night under the control of the master clock located in the suprachiasmatic nuclei of the hypothalamus. Under physiological conditions, the pineal gland seems to constitute the unique source of circulating melatonin. Melatonin is involved in cellular metabolism in different ways. First, the circadian rhythm of melatonin helps the maintenance of proper internal timing, the disruption of which has deleterious effects on metabolic health. Second, melatonin modulates lipid metabolism, notably through diminished lipogenesis, and it has an antidiabetic effect, at least in several animal models. Third, pharmacological doses of melatonin have antioxidative, free radical-scavenging, and anti-inflammatory properties in various in vitro cellular models. As a result, melatonin can be considered both a circadian time-giver and a homeostatic monitor of cellular metabolism, via multiple mechanisms of action that are not all fully characterized. Aging, circadian disruption, and artificial light at night are conditions combining increased metabolic risks with diminished circulating levels of melatonin. Accordingly, melatonin supplementation could be of potential therapeutic value in the treatment or prevention of metabolic disorders. More clinical trials in controlled conditions are needed, notably taking greater account of circadian rhythmicity.

The Positive Association between Melatonin-Containing Food Consumption and Older Adult Life Satisfaction, Psychoemotional State, and Cognitive Function

The purpose of this study was to test the hypothesis that melatonin-containing food (FMT) consumption is associated with a better sleep schedule and cognitive and psychoemotional state in older adults. A cross-sectional study of 557 (79% females) older adults living in the community with a mean age of 68.9 ± 7.7, ranging from 50 to 90 years, was conducted. The study, conducted in May and September 2023 using a face-to-face interview, collected personal data and assessed FMT intake during the day (FMTday) and for dinner (FMTdinner), life satisfaction, positive and negative affect, depression severity, cognitive functions, and sleep characteristics. Multiple regression and logistic regression analysis, adjusted for co-factors, were used to assess the association between the studied indicators. Multiple regression analysis showed that older adults with higher FMT consumption are more satisfied with life (FMTdinner: β = 0.107; ∆R2 = 0.011; p = 0.020), have a lower level of depression (FMTday: β = -0.124; ∆R2 = 0.015; p = 0.003), and higher scores in positive affect (FMTday: β = 0.169; ∆R2 = 0.016; p = 0.007; FMTdinner: β = 0.136; ∆R2 = 0.019; p = 0.003). Logistic regression analysis showed that older adults with higher FMT consumption are less likely to have depression (FMTday: OR, 0.614; 95% CI, 0.436-0.864; p = 0.005; FMTdinner: OR, 0.671; 95% CI, 0.476-0.945; p = 0.023), and they perform better on logical thinking tests (FMTday: OR, 2.066; 95% CI, 1.131-2.204; p = 0.013; FMTdinner: OR, 1.887; 95% CI, 1.183-2.138; p = 0.033). A greater life satisfaction as well as a decrease in the cognitive impairment and psychoemotional state of older adults is associated with a higher consumption of melatonin-containing foods.

Mitochondria: A Promising Convergent Target for the Treatment of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by the progressive loss of motor neurons, for which current treatment options are limited. Recent studies have shed light on the role of mitochondria in ALS pathogenesis, making them an attractive therapeutic intervention target. This review contains a very comprehensive critical description of the involvement of mitochondria and mitochondria-mediated mechanisms in ALS. The review covers several key areas related to mitochondria in ALS, including impaired mitochondrial function, mitochondrial bioenergetics, reactive oxygen species, metabolic processes and energy metabolism, mitochondrial dynamics, turnover, autophagy and mitophagy, impaired mitochondrial transport, and apoptosis. This review also highlights preclinical and clinical studies that have investigated various mitochondria-targeted therapies for ALS treatment. These include strategies to improve mitochondrial function, such as the use of dichloroacetate, ketogenic and high-fat diets, acetyl-carnitine, and mitochondria-targeted antioxidants. Additionally, antiapoptotic agents, like the mPTP-targeting agents minocycline and rasagiline, are discussed. The paper aims to contribute to the identification of effective mitochondria-targeted therapies for ALS treatment by synthesizing the current understanding of the role of mitochondria in ALS pathogenesis and reviewing potential convergent therapeutic interventions. The complex interplay between mitochondria and the pathogenic mechanisms of ALS holds promise for the development of novel treatment strategies to combat this devastating disease.

Melatonin in Alzheimer's Disease: Literature Review and Therapeutic Trials

There are currently no effective treatments to prevent, halt, or reverse Alzheimer's disease (AD), the most common cause of dementia in older adults. Melatonin, a relatively harmless over-the-counter supplement, may offer some benefits to patients with AD. Melatonin is known for its sleep-enhancing properties, but research shows that it may provide other advantages as well, such as antioxidant and anti-amyloidogenic properties. Clinical trials for melatonin use in AD have mixed results but, overall, show modest benefits. However, it is difficult to interpret clinical research in this area as there is little standardization to guide the administration and study of melatonin. This review covers basic biology and clinical research on melatonin in AD focusing on prominent hypotheses of pathophysiology of neurodegeneration and cognitive decline in AD (i.e., amyloid and tau hypotheses, antioxidant and anti-inflammation, insulin resistance and glucose homeostasis, the cholinergic hypothesis, sleep regulation, and the hypothalamic-pituitary-adrenal axis and cortisol). This is followed by a discussion on pending clinical trials, considerations for future research protocols, and open questions in the field.

Melatonin Exerts an Anti-Panoptoic Role in Spinal Cord Ischemia-Reperfusion Injured Rats

Paraplegia is a serious consequence of spinal cord ischemia-reperfusion (SCIR) injury, which leads to neuron death and permanent loss of motor function. However, there is no effective treatment for SCIR. Melatonin exerts a neuroprotective effect in neurodegenerative diseases. However, whether pyroptosis, apoptosis, and necroptosis (PANoptosis) is the primary cause of the massive neural death in SCIR is unknown, and if melatonin exhibits anti-PANoptotic effect in rescuing the disastrous damage is to be decided. This study indicates that melatonin confers neuroprotection in SCIR, attenuating the loss of Nissl body and improving Basso, Beattie & Bresnahan locomotor rating scale scores. Specifically, the apoptotic hallmarks in neurons are increased in SCIR injured spinal cord compared to the sham group. The upregulated trend is reversed by melatonin while the effect of melatonin is abolished by the administration of luzindole, a selective melatonin receptor antagonist. Moreover, similar patterns are found in the necroptotic markers in neurons, the pyroptotic indicators, and the interleukin-1β staining in microglia. In conclusion, PANoptosis may underlie the mass neural death and paraplegia in SCIR, and melatonin confers neuroprotection to the spinal cord via inhibiting PANoptosis.

Ramelteon attenuates hippocampal neuronal loss and memory impairment following kainate-induced seizures

Evidence suggests that the neuroprotective effects of melatonin involve both receptor-dependent and -independent actions. However, little is known about the effects of melatonin receptor activation on the kainate (KA) neurotoxicity. This study examined the effects of repeated post-KA treatment with ramelteon, a selective agonist of melatonin receptors, on neuronal loss, cognitive impairment, and depression-like behaviors following KA-induced seizures. The expression of melatonin receptors decreased in neurons, whereas it was induced in astrocytes 3 and 7 days after seizures elicited by KA (0.12 μg/μL) in the hippocampus of mice. Ramelteon (3 or 10 mg/kg, i.p.) and melatonin (10 mg/kg, i.p.) mitigated KA-induced oxidative stress and impairment of glutathione homeostasis and promoted the nuclear translocation and DNA binding activity of Nrf2 in the hippocampus after KA treatment. Ramelteon and melatonin also attenuated microglial activation but did not significantly affect astroglial activation induced by KA, despite the astroglial induction of melatonin receptors after KA treatment. However, ramelteon attenuated KA-induced proinflammatory phenotypic changes in astrocytes. Considering the reciprocal regulation of astroglial and microglial activation, these results suggest ramelteon inhibits microglial activation by regulating astrocyte phenotypic changes. These effects were accompanied by the attenuation of the nuclear translocation and DNA binding activity of nuclear factor κB (NFκB) induced by KA. Consequently, ramelteon attenuated the KA-induced hippocampal neuronal loss, memory impairment, and depression-like behaviors; the effects were comparable to those of melatonin. These results suggest that ramelteon-mediated activation of melatonin receptors provides neuroprotection against KA-induced neurotoxicity in the mouse hippocampus by activating Nrf2 signaling to attenuate oxidative stress and restore glutathione homeostasis and by inhibiting NFκB signaling to attenuate neuroinflammatory changes.

Melatonin and Related Compounds as Antioxidants

Oxidative stress has been reported to be involved in the onset and development of several diseases, including neurodegenerative and cardiovascular disorders, some types of cancer, and diabetes. Therefore, finding strategies to detoxify free radicals is an active area of research. One of these strategies is the use of natural or synthetic antioxidants. In this context, melatonin (MLT) has been proven to possess most of the required characteristics of an efficient antioxidant. In addition, its protection against oxidative stress continues after being metabolized, since its metabolites also exhibit antioxidant capacity. Based on the appealing properties of MLT and its metabolites, various synthetic analogues have been developed to obtain compounds with higher activity and lower side effects. This review addresses recent studies with MLT and related compounds as potential antioxidants.

[Melatonin reverses oxidative damage in the submandibular gland of rats treated with Cyclophosphamide]

Objetive

Cyclophosphamide (Cf) produces oxidative damage in rat submandibular gland (GSM). In the present work we evaluated the antioxidant protective effect of melatonin (MLT) in GSM of rats treated with Cf.

Methods

40 adult male Wistar rats were divided into 5 groups (G): G1: control; G2: Control+Ethanol: treated with 1% ethanol for 10 consecutive days. On days 11 and 12 they received a dose of saline; G3: Cf: treated with 1% ethanol for 12 days, days 11 and 12 they received an intraperitoneal (i.p.) dose of Cf 50 mg/Kg/kg of saline. ) of Cf 50 mg/kg bw; G4: Cf + MLT: MLT (5 mg/kg bw, intraperitoneal, dissolved in 1% ethanol) was administered daily, days 11 and 12 received Cf same as G3; G5: MLT: treated 12 consecutive days with MLT (same dose as G4). After 12 hours of fasting, animals were anesthetized to obtain both submandibular glands, then they were sacrificed. Uric acid (UA), lipid peroxides (LPs), aqueous peroxides (APs) and superoxide dismutase (SOD) activity were measured in submandibular gland homogenate. Statistical analysis: we used ANOVA and Bonferroni test pos hoc, considering significant p<0.05.

Results

Cf treatment decreased AU concentration and SOD activity (AU, mg/mg prot., G1: 2.50±0.68; G2: 2.18±0.13; G3: 0.54±0.09* G4: 1.95±0.24#, G5: 2.64±0.47, *p<0.01 G3 vs G1, G2, G4; #p<0.01 G4 vs G3 and G5; SOD, U/mg prot, G1: 4.57±0.95, G2: 4.79±0.94, G3: 2.18±0.53*, G4: 5.13±1.10, G5: 5.09±0.39, *p< 0.01 G3 vs G1, G2, G4 and G5). MLT treatment prevented these effects. In addition, Cf increased PL and PA formation.

Conclusion

MLT improved the redox status in GSM of Cf-treated rats. MLT could prevent oxidative processes in GSM produced by Cf.

Stress-related cellular pathophysiology as a crosstalk risk factor for neurocognitive and psychiatric disorders

In this narrative review, we examine biological processes linking psychological stress and cognition, with a focus on how psychological stress can activate multiple neurobiological mechanisms that drive cognitive decline and behavioral change. First, we describe the general neurobiology of the stress response to define neurocognitive stress reactivity. Second, we review aspects of epigenetic regulation, synaptic transmission, sex hormones, photoperiodic plasticity, and psychoneuroimmunological processes that can contribute to cognitive decline and neuropsychiatric conditions. Third, we explain mechanistic processes linking the stress response and neuropathology. Fourth, we discuss molecular nuances such as an interplay between kinases and proteins, as well as differential role of sex hormones, that can increase vulnerability to cognitive and emotional dysregulation following stress. Finally, we explicate several testable hypotheses for stress, neurocognitive, and neuropsychiatric research. Together, this work highlights how stress processes alter neurophysiology on multiple levels to increase individuals' risk for neurocognitive and psychiatric disorders, and points toward novel therapeutic targets for mitigating these effects. The resulting models can thus advance dementia and mental health research, and translational neuroscience, with an eye toward clinical application in cognitive and behavioral neurology, and psychiatry.

Setting the clinical context to non-motor symptoms reflected by Park-pain, Park-sleep, and Park-autonomic subtypes of Parkinson's disease

Non-motor symptoms (NMS) of Parkinson's disease (PD) are well described in both clinical practice and the literature, enabling their management and enhancing our understanding of PD. NMS can dominate the clinical pictures and NMS subtypes have recently been proposed, initially based on clinical observations, and later confirmed in data driven analyses of large datasets and in biomarker-based studies. In this chapter, we provide an update on what is known about three common subtypes of NMS in PD. The pain (Park-pain), sleep dysfunction (Park-sleep), and autonomic dysfunction (Park-autonomic), providing an overview of their individual classification, clinical manifestation, pathophysiology, diagnosis, and potential treatments.

Prophylactic supplement with melatonin prevented the brain injury after cardiac arrest in rats

Prophylactic pharmacotherapy for health care in patients with high risk of cardiac arrest (CA) is an elusive and less explored strategy. Melatonin has possibilities used as a daily nutraceutical to trigger the cellular adaptation. We sought to find the effects of long-term daily prophylactic supplement with melatonin on the victim of CA. Rats were divided into sham, CA, and melatonin + CA (Mel + CA) groups. The rats in the Mel + CA group received daily IP injection of melatonin 100 mg/kg for 14 days. CA was induced by 8 min asphyxia and followed by manual cardiopulmonary resuscitation. The endpoint was 24 h after resuscitation. Survival, neurological outcome, and hippocampal mitochondrial integrity, dynamics and function were assessed. Survival was significantly higher in the Mel + CA group than the CA group (81 vs. 42%, P = 0.04). Compared to the CA group, neurological damage in the CA1 region and the level of cytochrome c, cleaved caspase-3 and caspase-9 in the Mel + CA group were decreased (P < 0.05). Mitochondrial function and integrity were protected in the Mel + CA group compared to the CA group, according to the results of mitochondrial swelling, ΔΨm, ROS production, oxygen consumption rate, and respiratory control rate (P < 0.05). Melatonin increased SIRT3 and downregulated acetylated CypD. The mitochondrial dynamics and autophagy were improved in the Mel + CA group (P < 0.05). Long-term daily prophylactic supplement with melatonin buy the time from brain injury after CA.

Effect of neonatal melatonin administration on behavioral and brain electrophysiological and redox imbalance in rats

Introduction

Melatonin (MLT) reportedly has beneficial effects in neurological disorders involving brain excitability (e.g., Epilepsy and Migraine) and behavioral patterns (e.g., Anxiety and Depression). This study was performed to investigate, in the developing rat brain, the effect of early-in-life administration of two different doses of exogenous MLT on behavioral (anxiety and memory) and electrophysiological (CSD analysis) aspects of brain function. Additionally, brain levels of malondialdehyde (MDA) and superoxide dismutase (SOD), both cellular indicators of redox balance status, were evaluated. We hypothesize that MLT differentially affects the behavioral and CSD parameters as a function of the MLT dose.

Materials and methods

Male Wistar rats received, from the 7th to the 27th postnatal day (PND), on alternate days, vehicle solution, or 10 mg/kg/or 40 mg/kg MLT (MLT-10 and MLT-40 groups), or no treatment (intact group). To perform behavioral and cognition analysis, from PND30 to PND32, they were tested in the open field apparatus, first for anxiety (PND30) and then for object recognition memory tasks: spatial position recognition (PND31) and shape recognition (PND32). On PND34, they were tested in the elevated plus maze. From PND36 to 42, the excitability-related phenomenon known as cortical spreading depression (CSD) was recorded, and its features were analyzed.

Results

Treatment with MLT did not change the animals' body weight or blood glucose levels. The MLT-10 treatment, but not the MLT-40 treatment, was associated with behaviors that suggest less anxiety and improved memory. MLT-10 and MLT-40 treatments, respectively, decelerated and accelerated CSD propagation (speed of 2.86 ± 0.14 mm/min and 3.96 ± 0.16 mm/min), compared with the control groups (3.3 ± 0.10 mm/min and 3.25 ± 0.11 mm/min, for the intact and vehicle groups, respectively; p < 0.01). Cerebral cortex levels of malondialdehyde and superoxide dismutase were, respectively, lower and higher in the MLT-10 group but not in the MLT40 group.

Conclusion

Our findings suggest that MLT intraperitoneal administration during brain development may differentially act as an antioxidant agent when administered at a low dose but not at a high dose, according to behavioral, electrophysiological, and biochemical parameters.

Long-Term Effects of Perinatal Exposure to a Glyphosate-Based Herbicide on Melatonin Levels and Oxidative Brain Damage in Adult Male Rats

Concerns have been raised regarding the potential adverse health effects of the ubiquitous herbicide glyphosate. Here, we investigated long-term effects of developmental exposure to a glyphosate-based herbicide (GBH) by analyzing serum melatonin levels and cellular changes in the striatum of adult male rats (90 days old). Pregnant and lactating rats were exposed to 3% GBH (0.36% glyphosate) through drinking water from gestational day 5 to postnatal day 15. The offspring showed reduced serum melatonin levels (43%) at the adult age compared with the control group. The perinatal exposure to GBH also induced long-term oxidative stress-related changes in the striatum demonstrated by increased lipid peroxidation (45%) and DNA/RNA oxidation (39%) together with increased protein levels of the antioxidant enzymes, superoxide dismutase (SOD1, 24%), glutamate-cysteine ligase (GCLC, 58%), and glutathione peroxidase 1 (GPx1, 31%). Moreover, perinatal GBH exposure significantly increased the total number of neurons (20%) and tyrosine hydroxylase (TH)-positive neurons (38%) in the adult striatum. Mechanistic in vitro studies with primary rat pinealocytes exposed to 50 µM glyphosate demonstrated a decreased melatonin secretion partially through activation of metabotropic glutamate receptor 3 (mGluR3), while higher glyphosate levels (100 or 500 µM) also reduced the pinealocyte viability. Since decreased levels of the important antioxidant and neuroprotector melatonin have been associated with an increased risk of developing neurodegenerative disorders, this demonstrates the need to consider the melatonin hormone system as a central endocrine-related target of glyphosate and other environmental contaminants.

Timing Matters: The Interplay between Early Mealtime, Circadian Rhythms, Gene Expression, Circadian Hormones, and Metabolism-A Narrative Review

Achieving synchronization between the central and peripheral body clocks is essential for ensuring optimal metabolic function. Meal timing is an emerging field of research that investigates the influence of eating patterns on our circadian rhythm, metabolism, and overall health. This narrative review examines the relationship between meal timing, circadian rhythm, clock genes, circadian hormones, and metabolic function. It analyzes the existing literature and experimental data to explore the connection between mealtime, circadian rhythms, and metabolic processes. The available evidence highlights the importance of aligning mealtime with the body's natural rhythms to promote metabolic health and prevent metabolic disorders. Specifically, studies show that consuming meals later in the day is associated with an elevated prevalence of metabolic disorders, while early time-restricted eating, such as having an early breakfast and an earlier dinner, improves levels of glucose in the blood and substrate oxidation. Circadian hormones, including cortisol and melatonin, interact with mealtimes and play vital roles in regulating metabolic processes. Cortisol, aligned with dawn in diurnal mammals, activates energy reserves, stimulates appetite, influences clock gene expression, and synchronizes peripheral clocks. Consuming meals during periods of elevated melatonin levels, specifically during the circadian night, has been correlated with potential implications for glucose tolerance. Understanding the mechanisms of central and peripheral clock synchronization, including genetics, interactions with chronotype, sleep duration, and hormonal changes, provides valuable insights for optimizing dietary strategies and timing. This knowledge contributes to improved overall health and well-being by aligning mealtime with the body's natural circadian rhythm.

Melatonin modulates tumor metabolism and mitigates metastasis

INTRODUCTION

Melatonin, originally isolated from the mammalian pineal gland, was subsequently identified in many animal cell types and in plants. While melatonin was discovered to inhibit cancer more than 5 decades ago, its anti-cancer potential has not been fully exploited despite its lack of serious toxicity over a very wide dose range, high safety margin, and its efficacy.

AREAS COVERED

This review elucidates the potential mechanisms by which melatonin interferes with tumor growth and metastasis, including its ability to alter tumor cell metabolism, inhibit epithelial-mesenchymal transition, reverse cancer chemoresistance, function synergistically with conventional cancer-inhibiting drugs while limiting many of their side effects. In contrast to its function as a potent antioxidant in normal cells, it may induce oxidative stress in cancer cells, contributing to its oncostatic actions.

EXPERT OPINION

Considering the large amount of experimental data supporting melatonin's multiple and varied inhibitory effects on numerous cancer types, coupled with the virtual lack of toxicity of this molecule, it has not been thoroughly tested as an anti-cancer agent in clinical trials. There seems to be significant resistance to such investigations, possibly because melatonin is inexpensive and non-patentable, and as a result there would be limited financial gain for its use.

Melatonin: a promising neuroprotective agent for cerebral ischemia-reperfusion injury

Cerebral ischemia-reperfusion (CIR) injury is initiated by the generation of reactive oxygen species (ROS), which leads to the oxidation of cellular proteins, DNA, and lipids as an initial event. The reperfusion process impairs critical cascades that support cell survival, including mitochondrial biogenesis and antioxidant enzyme activity. Failure to activate prosurvival signals may result in increased neuronal cell death and exacerbation of CIR damage. Melatonin, a hormone produced naturally in the body, has high concentrations in both the cerebrospinal fluid and the brain. However, melatonin production declines significantly with age, which may contribute to the development of age-related neurological disorders due to reduced levels. By activating various signaling pathways, melatonin can affect multiple aspects of human health due to its diverse range of activities. Therefore, understanding the underlying intracellular and molecular mechanisms is crucial before investigating the neuroprotective effects of melatonin in cerebral ischemia-reperfusion injury.

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.

Chrono-modulated effects of external stressors on oxidative stress and damage in humans: A scoping review on night shift work

BACKGROUND

Oxidative stress and tissue damage (OSD) play a pivotal role as an early-stage process in chronic disease pathogenesis. However, there has been little research to better understand the temporal (χρόνος[chronos]) dimensions of OSD process associated with environmental (non-genetic, including behaviors/lifestyle) and/or occupational stressors, like night shift work. OSD processes have recently attracted attention in relation to time-resolved external stressor trajectories in personalized medicine (prevention) initiatives, as they seem to interact with circadian clock systems towards the improved delineation of the early stages of (chronic) disease process.

OBJECTIVES

This work critically reviewed human studies targeting the temporal dynamics of OSD and circadian clock system's activity in response to environmental/occupational stressors; the case of night shift work was examined.

METHODS

Being a key stressor influencing OSD processes and circadian rhythm, night shift work was evaluated as part of a scoping review of research in OSD, including inflammatory and metabolic processes to determine the extent of OSD research undertaken in human populations, methodologies, tools and biomarkers used and the extent that the temporal dimensions of exposure and biological effect(s) were accounted for. Online databases were searched for papers published from 2000 onwards, resulting in the selection of 53 original publications.

RESULTS AND DISCUSSION

The majority of studies (n = 41) took place in occupational settings, while the rest were conducted in the general population or patient groups. Most occupational studies targeted outcomes of oxidative stress/damage (n = 19), followed by the combination of OSD with inflammatory response (n = 10), and studies focused on metabolic outcomes (n = 12). Only a minor fraction of the studies measured biomarkers related to circadian rhythm, such as, melatonin, its metabolite, or cortisol. Night shift work was associated with select biomarkers of OSD and inflammation, albeit with mixed results. Although much progress in delineating the biological mechanisms of OSD process has been made, an equally thorough investigation on the temporal trajectory of OSD processes as triggered by environmental/occupational stressors in human studies has yet to fully evolve.

Role of microglia autophagy and mitophagy in age-related neurodegenerative diseases

Microglia, characterized by responding to damage, regulating the secretion of soluble inflammatory mediators, and engulfing specific segments in the central nervous system (CNS), function as key immune cells in the CNS. Emerging evidence suggests that microglia coordinate the inflammatory responses in CNS system and play a pivotal role in the pathogenesis of age-related neurodegenerative diseases (NDDs). Remarkably, microglia autophagy participates in the regulation of subcellular substances, which includes the degradation of misfolded proteins and other harmful constituents produced by neurons. Therefore, microglia autophagy regulates neuronal homeostasis maintenance and process of neuroinflammation. In this review, we aimed at highlighting the pivotal role of microglia autophagy in the pathogenesis of age-related NDDs. Besides the mechanistic process and the co-interaction between microglia autophagy and different kinds of NDDs, we also emphasized potential therapeutic agents and approaches that could be utilized at the onset and progression of these diseases through modulating microglia autophagy, including promising nanomedicines. Our review provides a valuable reference for subsequent studies focusing on treatments of neurodegenerative disorders. The exploration of microglia autophagy and the development of nanomedicines greatly enhances current understanding of NDDs.

Role of Oxidative Stress on the Etiology and Pathophysiology of Amyotrophic Lateral Sclerosis (ALS) and Its Relation with the Enteric Nervous System

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons in the spinal cord, cerebral cortex, and medulla oblongata. Most patients present a clinical phenotype of classic ALS-with predominant atrophy, muscle weakness, and fasciculations-and survival of 3 to 5 years following diagnosis. In the present review, we performed a literature search to provide an update on the etiology and pathophysiological mechanisms involved in ALS. There are two types of ALS: the familial form with genetic involvement, and the sporadic form with a multifactorial origin. ALS pathophysiology is characterized by involvement of multiple processes, including oxidative stress, glutamate excitotoxicity, and neuroinflammation. Moreover, it is proposed that conditioning risk factors affect ALS development, such as susceptibility to neurodegeneration in motor neurons, the intensity of performed physical activity, and intestinal dysbiosis with involvement of the enteric nervous system, which supports the existing theories of disease generation. To improve patients' prognosis and survival, it is necessary to further deepen our understanding of the etiopathogenesis of ALS.

Melatonin Treatment in Kidney Diseases

Melatonin is a neurohormone that is mainly secreted by the pineal gland. It coordinates the work of the superior biological clock and consequently affects many processes in the human body. Disorders of the waking and sleeping period result in nervous system imbalance and generate metabolic and endocrine derangements. The purpose of this review is to provide information regarding the potential benefits of melatonin use, particularly in kidney diseases. The impact on the cardiovascular system, diabetes, and homeostasis causes melatonin to be indirectly connected to kidney function and quality of life in people with chronic kidney disease. Moreover, there are numerous reports showing that melatonin plays a role as an antioxidant, free radical scavenger, and cytoprotective agent. This means that the supplementation of melatonin can be helpful in almost every type of kidney injury because inflammation, apoptosis, and oxidative stress occur, regardless of the mechanism. The administration of melatonin has a renoprotective effect and inhibits the progression of complications connected to renal failure. It is very important that exogenous melatonin supplementation is well tolerated and that the number of side effects caused by this type of treatment is low.

Beyond sleep: A multidimensional model of chronotype

Chronotype can be defined as an expression or proxy for circadian rhythms of varied mechanisms, for example in body temperature, cortisol secretion, cognitive functions, eating and sleeping patterns. It is influenced by a range of internal (e.g., genetics) and external factors (e.g., light exposure), and has implications for health and well-being. Here, we present a critical review and synthesis of existing models of chronotype. Our observations reveal that most existing models and, as a consequence, associated measures of chronotype have focused solely or primarily on the sleep dimension, and typically have not incorporated social and environmental influences on chronotype. We propose a multidimensional model of chronotype, integrating individual (biological and psychological), environmental and social factors that appear to interact to determine an individual's true chronotype with potential feedback loops between these factors. This model could be beneficial not only from a basic science perspective but also in the context of understanding health and clinical implications of certain chronotypes as well as designing preventive and therapeutic approaches for related illnesses.

Melatonin Mitigates Rotenone-Induced Oxidative Stress and Mitochondrial Dysfunction in the Drosophila melanogaster Model of Parkinson's Disease-like Symptoms

Parkinson's disease (PD) is the second most common neurodegenerative disorder; however, its etiology remains elusive. Antioxidants are considered to be a promising approach for decelerating neurodegenerative disease progression owing to extensive examination of the relationship between oxidative stress and neurodegenerative diseases. In this study, we investigated the therapeutic effect of melatonin against rotenone-induced toxicity in the Drosophila model of PD. The 3-5 day old flies were divided into four groups: control, melatonin alone, melatonin and rotenone, and rotenone alone groups. According to their respective groups, flies were exposed to a diet containing rotenone and melatonin for 7 days. We found that melatonin significantly reduced the mortality and climbing ability of Drosophila because of its antioxidative potency. It alleviated the expression of Bcl 2, tyrosine hydroxylase (TH), NADH dehydrogenase, mitochondrial membrane potential, and mitochondrial bioenergetics and decreased caspase 3 expression in the Drosophila model of rotenone-induced PD-like symptoms. These results indicate the neuromodulatory effect of melatonin, and that it is likely modulated against rotenone-induced neurotoxicity by suppressing oxidative stress and mitochondrial dysfunctions.

Analysis of Melatonin-Modulating Effects Against Tartrazine-Induced Neurotoxicity in Male Rats: Biochemical, Pathological and Immunohistochemical Markers

Tartrazine (E-102) is one of the most widely used artificial food azo-colors that can be metabolized to highly sensitizing aromatic amines such as sulphanilic acid. These metabolites are oxidized to N-hydroxy derivatives that cause neurotoxicity. Melatonin is a neurohormone. That possesses a free-radical scavenging effect. The present work was mainly designed to evaluate the possible ameliorative role of melatonin against tartrazine induced neurotoxicity in cerebral cortex and cerebellum of male rats. Adult male rats were administered orally with tartrazine (7.5 mg/kg) with or without melatonin (10 mg/kg) daily for four weeks. The data revealed that tartrazine induced redox disruptions as measured by significant (p < 0.05) increased malondialdehyde (MDA) level and inhibition of (GSH) concentration and catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) antioxidant enzyme activities. Besides, brain acetyl cholin (Ach) and gamma-aminobutyric acid (GABA) were elevated while, dopamine (DA) was depleted in trtrazine -treated rats. Moreover, tartrazine caused a significant (p < 0.05) increase in the brain interleukin-6 (IL-6), interleukin-1β (IL-1 β) and tumor necrosis factor-α (TNFα). At the tissue level, tartrazine caused severe histopathological changes in the cerebellum and cerebral cortex of rats. The immunohistochemical results elucidated strong positive expression for Caspase-3 and GFAP and weak immune reaction for BcL2 and synaptophysin in tatrazine- treated rats. The administration of melatonin to tartrazine -administered rats remarkably alleviated all the aforementioned tartrzine-induced effects. It could be concluded that, melatonin has a potent ameliorative effect against tartrazine induced neurotoxicity via the attenuation of oxidative/antioxidative responses.

Melatonin signalling in Schwann cells during neuroregeneration

It has widely been thought that in the process of nerve regeneration Schwann cells populate the injury site with myelinating, non–myelinating, phagocytic, repair, and mesenchyme–like phenotypes. It is now clear that the Schwann cells modify their shape and basal lamina as to accommodate re–growing axons, at the same time clear myelin debris generated upon injury, and regulate expression of extracellular matrix proteins at and around the lesion site. Such a remarkable plasticity may follow an intrinsic functional rhythm or a systemic circadian clock matching the demands of accurate timing and precision of signalling cascades in the regenerating nervous system. Schwann cells react to changes in the external circadian clock clues and to the Zeitgeber hormone melatonin by altering their plasticity. This raises the question of whether melatonin regulates Schwann cell activity during neurorepair and if circadian control and rhythmicity of Schwann cell functions are vital aspects of neuroregeneration. Here, we have focused on different schools of thought and emerging concepts of melatonin–mediated signalling in Schwann cells underlying peripheral nerve regeneration and discuss circadian rhythmicity as a possible component of neurorepair.

Melatonin as an oncostatic agent: Review of the modulation of tumor microenvironment and overcoming multidrug resistance

Multi drug resistance (MDR) generally limits the efficacy of chemotherapy in cancer patients and can be categorized into primary or acquired resistance. Melatonin (MLT), a lipophilic hormone released from pineal gland, is a molecule with oncostatic effects. Here, we will briefly review the contribution of different microenvironmental components including fibroblasts, immune and inflammatory cells, stem cells and vascular endothelial cells in tumor initiation, progression and development. Then, the mechanisms by which MLT can potentially affect these elements and regulate drug resistance will be presented. Finally, we will explain how different studies have used novel strategies incorporating MLT to suppress cancer resistance against therapeutics.

Neuromodulatory and Protective Effects Induced by the Association of Herbal Extracts from Valeriana officinalis, Ziziphus jujuba, and Humulus lupulus with Melatonin: An Innovative Formulation for Counteracting Sleep Disorders

Background: The use of herbal extracts could represent an advantageous approach for treating sleeping disorders, especially in mild-to-moderate conditions, before the onset of a specific therapy with first-line drugs. Specifically, the focus was posed about the use of extracts from Valeriana officinalis, Ziziphus jujuba, and Humulus lupulus. Multiple studies demonstrated the efficacy of these medicinal plants to positively manage insomnia symptoms. Additionally, their efficacy in the treatment of sleeping disorders could also be improved by their pharmacological association. In the present study, extracts from Valeriana officinalis, Ziziphus jujuba, Humulus lupulus, melatonin, and their pharmacological association, Vagonotte® MEL, were studied for potential application in the treatment of insomnia. Methods: The extracts and melatonin were tested on hypothalamic neurons and tissue for evaluating biocompatibility and protective and neuromodulatory effects. The neuromodulatory effects were evaluated as orexin A gene expression and serotonin steady state level, in the hypothalamus. Results: The extracts and melatonin, although with evident differences, were effective as antioxidant and anti-inflammatory agents; additionally, they were also able to reduce the hypothalamic gene expression of orexin A and the steady state level of serotonin, playing master roles in wakefulness. It is noteworthy that the formulation displayed all the effects of the single ingredients, without any sign of toxicity and pharmacological interference in the hypothalamus. Conclusions: Concluding, the present study explored the biological effects of melatonin and herbal extracts with phytotherapy interest in V. officinalis, Z. jujuba, and H. lupulus. The study demonstrated their intrinsic scavenging/reducing activity, together with protective and neuromodulatory effects in the hypothalamus, with a significant reduction of both orexin A gene expression and serotonin steady state level. Additionally, the study also considered their pharmacological association, which displayed an overall pharmacological spectrum mirroring, including all the effects of the single ingredients, without showing any sign of toxicity in the brain and interference between the extracts and melatonin.

Melatonin Attenuates Methotrexate-Induced Reduction of Antioxidant Activity Related to Decreases of Neurogenesis in Adult Rat Hippocampus and Prefrontal Cortex

Previous studies have revealed that the side effects of anticancer drugs induce a decrease of neurogenesis. Methotrexate (MTX), one of anticancer drugs, can induce lipid peroxidation as an indicator of oxidative stress in the brain. Melatonin has been presented as an antioxidant that can prevent oxidative stress-induced neuronal damage via the activation of antioxidant enzymes associated with the increase of neurogenesis. The aims of the present study are to examine the neuroprotective effect of melatonin on the neurotoxicity of MTX on neurogenesis and the changes of protein expression and antioxidant enzyme levels in adult rat hippocampus and prefrontal cortex (PFC). Male Sprague-Dawley rats were assigned into four groups: vehicle, MTX, melatonin, and melatonin+MTX groups. The vehicle group received saline solution and 10% ethanol solution, whereas the experimental groups received MTX (75 mg/kg, i.v.) and melatonin (8 mg/kg, i.p.) treatments. After the animal examination, the brains were removed for p21 immunofluorescence staining. The hippocampus and PFC were harvested for Western blot analysis and biochemical assessments of malondialdehyde (MDA), catalase (CAT), glutathione peroxidase (GPX), and superoxide dismutase (SOD). The immunofluorescence result showed that coadministration with melatonin diminished p21-positive cells in the hippocampal dentate gyrus, indicating a decrease of cell cycle arrest. Melatonin reduced the levels of MDA and prevented the decline of antioxidant enzyme activities in rats receiving MTX. In the melatonin+MTX group, the protein expression results showed that melatonin treatment significantly upregulated synaptic plasticity and an immature neuron marker through enhancing brain derived neurotrophic factor (BDNF) and doublecortin (DCX), respectively. Moreover, melatonin ameliorated the antioxidant defense system by improving the nuclear factor erythroid 2-related factor 2 (Nrf2) in rats receiving MTX. These findings suggested that the effects of melatonin can ameliorate MTX toxicity by several mechanisms, including an increase of endogenous antioxidants and neurogenesis in adult rat hippocampus and PFC.

WNT/β-catenin Pathway: a Possible Link Between Hypertension and Alzheimer's Disease

PURPOSE OF REVIEW

Recent research has shown that older people with high blood pressure (BP), or hypertension, are more likely to have biomarkers of Alzheimer's disease (AD). Essential hypertension represents the most common cardiovascular disease worldwide and is thought to be responsible for about 13% of all deaths. People with essential hypertension who regularly take prescribed BP medications are half as likely to develop AD as those who do not take them. What then is the connection?

RECENT FINDINGS

We know that high BP can damage small blood vessels in the brain, affecting those parts that are responsible for memory and thinking. However, the link between AD and hypertension remains unclear. Recent advances in the field of molecular and cellular biology have revealed a downregulation of the canonical WNT/β-catenin pathway in both hypertension and AD. In AD, the glutamate transport function is decreased, a decrease that is associated with a loss of synapse and neuronal death. β-catenin signaling appears to act as a major regulator of glutamate transporters (EAAT and GS) expression and can be harnessed to remove excess glutamate in AD. This review focuses on the possible link between hypertension and AD through the decreased WNT/β-catenin which interacts with the glutamatergic pathway.

Colon targeted chitosan-melatonin nanotherapy for preclinical Inflammatory Bowel Disease

Inflammatory Bowel (IBD) is an umbrella term which includes Crohn's Disease (CD) and Ulcerative Colitis (UC). At present, therapies available for management of the UC includes, corticosteroid, immuno-suppressants and antibiotics are used for mild to moderate UC conditions which can cause nephrotoxicity, hepatotoxicity and cardiotoxicity. Hence, a novel therapeutic candidate having potent anti-inflammatory effect is urgently warranted for the management of UC. Melatonin has emerged as a potent anti-inflammatory agent. However, poor solubility limits its therapeutic potential. Therefore, colon targeted Eudragit-S-100 coated chitosan nanoparticles have been demonstrated to improve melatonin therapeutic efficacy. It was found that melatonin loaded chitosan and colon targeted chitosan nanoparticles had promising anti-inflammatory efficacy in terms of NO scavenging activity in an in-vitro LPS challenged macrophages. Also, colon targeted oral chitosan nano-formulation exhibited remarkable protection in an in vivo UC mice model by improving gross pathological parameters, histo-architectural protection, goblet cell depletion, and immune cells infiltration which can be extrapolated to clinical studies.

Targeting MicroRNA-144/451-AKT-GSK3β Axis Affects the Proliferation and Differentiation of Radial Glial Cells in the Mouse Hippocampal Dentate Gyrus

It is well known that aging induces a progressive decline in the proliferation and neural differentiation of radial glial cells (RGCs) in the hippocampal dentate gyrus (DG). The function of miR-144/451 is to activate stress-regulated molecular gene expression switches for cell proliferation and differentiation. We found that the miR-144/451 expression in the hippocampus was significantly reduced in aged mice compared to adult mice. Furthermore, the proliferation and neural differentiation of RGCs in the mouse hippocampal DG was decreased by miR-144/451 knockout (miR-144/451^-/-). Antioxidant agents, superoxide dismutases (SODs) and catalase, and the expression of melatonin's receptor in the hippocampus were decreased in the miR-144/451^-/- mice. In addition, the (protein kinase B) AKT/(glycogen synthase kinase 3β) GSK3β/(catenin beta-1) β-catenin signaling pathway was weakly activated in the hippocampus of miR-144/451^-/- mice, which was related to brain neurogenesis. Melatonin treatment improved the expression of miR-144/451 and antioxidant enzymes and activated the AKT/GSK3β/β-catenin pathway in the hippocampus of miR-144/451^-/- mice. When the AKT pathway was inhibited by LY294002, the neurogenerative and antioxidant effects of melatonin were significantly limited in the hippocampus of miR-144/451^-/- mice. In brief, our results indicated that miR-144/451 plays crucial roles in the proliferation and neural differentiation of RGCs via the regulation of the antioxidant and AKT/GSK3β/β-catenin pathways.

Melatonin as an antioxidant agent in disease prevention: A biochemical focus

Abstract:

In the recent years, free radicals and oxidative stress have been found to be associated with aging, cancer, atherosclerosis, neurodegenerative disorders, diabetes, and inflammatory diseases. Confirming the role of oxidants in numerous pathological situations including cancer, developing antioxidants as therapeutic platforms is needed. It has been well established that melatonin and its derived metabolites function as endogenous free-radical scavengers and broad spectrum antioxidants. To achieve this function, melatonin can directly detoxify reactive oxygen and reactive nitrogen species and indirectly overexpress antioxidant enzymes while suppressing the activity of pro-oxidant enzymes. Many investigations have also confirmed the role of melatonin and its derivatives in different physiological processes and therapeutic functions such as controlling the circadian rhythm and immune functions. This review aimed to focus on melatonin as a beneficial agent for the stimulation of antioxidant enzymes and inhibition of lipid peroxidation and to evaluate its contribution to protection against oxidative damages. In addition, the clinical application of melatonin in several diseases is discussed. Finally, the safety and efficacy of melatonin in clinical backgrounds is also reviewed.

The neurophysiologic basis of the human sleep–wake cycle and the physiopathology of the circadian clock: a narrative review

The objectives of this review were to explain the neurologic processes that control the human sleep–wake cycle as well as the pathophysiology of the human circadian clock. Non-rapid eye movement and rapid eye movement sleep are the two main phases of sleep. When triggered by circadian input from the anterior hypothalamus and sleep–wake homeostatic information from endogenous chemical signals (example, adenosine), the ventrolateral preoptic nucleus initiates the onset of sleep. Arousal in which there is a conscious monitoring of the surroundings and the ability to respond to external stimuli is known as wakefulness. It contrasts the state of sleep, in which receptivity to external stimuli is reduced. The higher the synchronous firing rates of cerebral cortex neurons, the longer the brain has been awake. Sleep–wake disturbances induced by endogenous circadian system disruptions or desynchronization between internal and external sleep–wake cycles are known as circadian rhythm sleep–wake disorder (CRSWD). Patients with CRSWD usually report chronic daytime drowsiness and/or insomnia, which interferes with their activities. CRSWD is diagnosed based on the results of some functional evaluations, which include measuring the circadian phase using core body temperature, melatonin secretion timing, sleep diaries, actigraphy, and subjective experiences (example, using the Morningness–Eveningness Questionnaire). CRSWD is classified as a dyssomnia in the second edition of the International Classification of Sleep Disorders, with six subtypes: advanced sleep phase, delayed sleep phase, irregular sleep–wake, free running, jet lag, and shift work types. CRSWD can be temporary (due to jet lag, shift work, or illness) or chronic (due to delayed sleep–wake phase disorder, advanced sleep–wake phase disorder, non-24-h sleep–wake disorder, or irregular sleep–wake rhythm disorder). The inability to fall asleep and wake up at the desired time is a common symptom of all CRSWDs.

Novel Series of Dual NRF2 Inducers and Selective MAO-B Inhibitors for the Treatment of Parkinson’s Disease

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disease. It is characterized by a complex network of physiopathological events where oxidative stress plays a central role among other factors such as neuroinflammation and protein homeostasis. Nuclear factor-erythroid 2 p45-related factor 2 (NRF2) has a multitarget profile itself as it controls a plethora of cellular processes involved in the progression of the disease. In this line, we designed a novel family of 2-(1H-indol-3-yl)ethan-1-amine derivatives as NRF2 inducers with complementary activities. Novel compounds are based on melatonin scaffold and include, among other properties, selective monoamine oxidase B (MAO-B) inhibition activity. Novel multitarget compounds exhibited NRF2 induction activity and MAO-B selective inhibition, combined with anti-inflammatory, antioxidant, and blood–brain barrier permeation properties. Furthermore, they exert neuroprotective properties against oxidative stress toxicity in PD-related in vitro. Hit compound 14 reduced oxidative stress markers and exerted neuroprotection in rat striatal slices exposed to 6-hydroxydopamine or rotenone. In conclusion, we developed a promising family of dual NRF2 inducers and selective MAO-B inhibitors that could serve as a novel therapeutic strategy for PD treatment.

Protective Role of Melatonin and Its Metabolites in Skin Aging

The skin, being the largest organ in the human body, is exposed to the environment and suffers from both intrinsic and extrinsic aging factors. The skin aging process is characterized by several clinical features such as wrinkling, loss of elasticity, and rough-textured appearance. This complex process is accompanied with phenotypic and functional changes in cutaneous and immune cells, as well as structural and functional disturbances in extracellular matrix components such as collagens and elastin. Because skin health is considered one of the principal factors representing overall “well-being” and the perception of “health” in humans, several anti-aging strategies have recently been developed. Thus, while the fundamental mechanisms regarding skin aging are known, new substances should be considered for introduction into dermatological treatments. Herein, we describe melatonin and its metabolites as potential “aging neutralizers”. Melatonin, an evolutionarily ancient derivative of serotonin with hormonal properties, is the main neuroendocrine secretory product of the pineal gland. It regulates circadian rhythmicity and also exerts anti-oxidative, anti-inflammatory, immunomodulatory, and anti-tumor capacities. The intention of this review is to summarize changes within skin aging, research advances on the molecular mechanisms leading to these changes, and the impact of the melatoninergic anti-oxidative system controlled by melatonin and its metabolites, targeting the prevention or reversal of skin aging.

Narcolepsy in Parkinson's disease with insulin resistance

Background: Parkinson’s disease (PD) is characterized by its progression of motor-related symptoms such as tremors, rigidity, slowness of movement, and difficulty with walking and balance. Comorbid conditions in PD individuals include insulin resistance (IR) and narcolepsy-like sleep patterns. The intersecting sleep symptoms of both conditions include excessive daytime sleepiness, hallucinations, insomnia, and falling into REM sleep more quickly than an average person. Understanding of the biological basis and relationship of these comorbid disorders with PD may help with early detection and intervention strategies to improve quality of life. Methods: In this study, an integrative genomics and systems biology approach was used to analyze gene expression patterns associated with PD, IR, and narcolepsy in order to identify genes and pathways that may shed light on how these disorders are interrelated. A correlation analysis with known genes associated with these disorders (LRRK2, HLA-DQB1, and HCRT) was used to query microarray data corresponding to brain regions known to be involved in PD and narcolepsy. This includes the hypothalamus, dorsal thalamus, pons, and subcoeruleus nucleus. Risk factor genes for PD, IR, and narcolepsy were also incorporated into the analysis. Results: The PD and narcolepsy signaling networks are connected through insulin and immune system pathways. Important genes and pathways that link PD, narcolepsy, and IR are CACNA1C, CAMK1D, BHLHE41, HMGB1, and AGE-RAGE. Conclusions: We have identified the genetic signatures that link PD with its comorbid disorders, narcolepsy and insulin resistance, from the convergence and intersection of dopaminergic, insulin, and immune system related signaling pathways. These findings may aid in the design of early intervention strategies and treatment regimes for non-motor symptoms in PD patients as well as individuals with diabetes and narcolepsy.

Exercise, Diet and Sleeping as Regenerative Medicine Adjuvants: Obesity and Ageing as Illustrations

Regenerative medicine uses the biological and medical knowledge on how the cells and tissue regenerate and evolve in order to develop novel therapies. Health conditions such as ageing, obesity and cancer lead to an impaired regeneration ability. Exercise, diet choices and sleeping pattern have significant impacts on regeneration biology via diverse pathways including reducing the inflammatory and oxidative components. Thus, exercise, diet and sleeping management can be optimized towards therapeutic applications in regenerative medicine. It could allow to prevent degeneration, optimize the biological regeneration and also provide adjuvants for regenerative medicine.