Melatonin, cardiolipin and mitochondrial bioenergetics in health and disease. J Pineal Res. 2010;48:297-310. [PMID: 20433638 DOI: 10.1111/j.1600-079x.2010.00759.x]

Effect of intravenous and intracoronary melatonin as an adjunct to primary percutaneous coronary intervention for acute ST-elevation myocardial infarction: Results of the Melatonin Adjunct in the acute myocaRdial Infarction treated with Angioplasty trial

The MARIA randomized trial evaluated the efficacy and safety of melatonin for the reduction of reperfusion injury in patients undergoing revascularization for ST-elevation myocardial infarction (STEMI). This was a prespecified interim analysis. A total of 146 patients presenting with STEMI within 6 hours of chest pain onset were randomized to receive intravenous and intracoronary melatonin (n=73) or placebo (n=73) during primary percutaneous coronary intervention (PPCI). Primary endpoint was myocardial infarct size as assessed by magnetic resonance imaging (MRI) at 6 ± 2 days. Secondary endpoints were changes in left ventricular volumes and ejection fraction (LVEF) at 130 ± 10 days post-PPCI and adverse events during the first year. No significant differences in baseline characteristics were observed between groups. MRI was performed in 108 patients (86.4%). Myocardial infarct size by MRI evaluated 6 ± 2 days post-PPCI, did not differ between melatonin and placebo groups (P=.63). Infarct size assessed by MRI at 130 ± 10 days post-PPCI, performed in 91 patients (72.8%), did not show statistically significant differences between groups (P=.27). The recovery of LVEF from 6 ± 2 to 130 ± 10 days post-PPCI was greater in the placebo group (60.0 ± 10.4% vs 53.1 ± 12.5%, P=.008). Both left ventricular end-diastolic and end-systolic volumes were lower in the placebo group (P=.01). The incidence of adverse events at 1 year was comparable in both groups (P=.150). Thus, in a nonrestricted STEMI population, intravenous and intracoronary melatonin was not associated with a reduction in infarct size and has an unfavourable effect on the ventricular volumes and LVEF evolution. Likewise, there is lack of toxicity of melatonin with the doses used.

Melatonin: A Mitochondrial Targeting Molecule Involving Mitochondrial Protection and Dynamics

Melatonin has been speculated to be mainly synthesized by mitochondria. This speculation is supported by the recent discovery that aralkylamine N-acetyltransferase/serotonin N-acetyltransferase (AANAT/SNAT) is localized in mitochondria of oocytes and the isolated mitochondria generate melatonin. We have also speculated that melatonin is a mitochondria-targeted antioxidant. It accumulates in mitochondria with high concentration against a concentration gradient. This is probably achieved by an active transportation via mitochondrial melatonin transporter(s). Melatonin protects mitochondria by scavenging reactive oxygen species (ROS), inhibiting the mitochondrial permeability transition pore (MPTP), and activating uncoupling proteins (UCPs). Thus, melatonin maintains the optimal mitochondrial membrane potential and preserves mitochondrial functions. In addition, mitochondrial biogenesis and dynamics is also regulated by melatonin. In most cases, melatonin reduces mitochondrial fission and elevates their fusion. Mitochondrial dynamics exhibit an oscillatory pattern which matches the melatonin circadian secretory rhythm in pinealeocytes and probably in other cells. Recently, melatonin has been found to promote mitophagy and improve homeostasis of mitochondria.

Outcomes of topical applications of melatonin in implant dentistry: a systematic review

BACKGROUND

Due to its antioxidant properties and its ability to detoxify free radicals, melatonin may interfere in the function of osteoclasts and thereby inhibit bone resorption. This inhibition of bone resorption may be enhanced by a reaction of indolamine in osteoclastogenesis and this may contribute to certain benefits in implantology.

OBJECTIVE

This systematic literature review on the use of melatonin in implant dentistry aims to provide guidelines for clinicians.

MATERIALS AND METHODS

PubMed, Science Direct, ISI Web of Knowledge, and the Cochrane base databases were used to identify articles published between 1999 and 2013 on melatonin use in implant dentistry. Ten articles were selected consisting of 9 animal research studies and 1 review article, involving 60 Beagle dogs, 57 rats, and 30 rabbits and a total of 352 implants.

RESULTS

Melatonin, which is released into the saliva, has important implications in the oral cavity. To achieve dental implant stability, osseointegration involves a cascade of protein and cell apposition, vascular invasion, bone formation, and maturation. This process may be accelerated by local delivery of growth-promoting factors, as occurs with the topical application of melatonin over the implant surface.

CONCLUSIONS

The experimental evidence suggests that topical applications of melatonin may be useful in oral surgery and implant dentistry, increasing bone-to-implant contact values and new bone formation, and so improving the success and long-term survival of implant treatments.

Nutraceuticals and Their Potential to Treat Duchenne Muscular Dystrophy: Separating the Credible from the Conjecture

In recent years, complementary and alternative medicine has become increasingly popular. This trend has not escaped the Duchenne Muscular Dystrophy community with one study showing that 80% of caregivers have provided their Duchenne patients with complementary and alternative medicine in conjunction with their traditional treatments. These statistics are concerning given that many supplements are taken based on purely "anecdotal" evidence. Many nutraceuticals are thought to have anti-inflammatory or anti-oxidant effects. Given that dystrophic pathology is exacerbated by inflammation and oxidative stress these nutraceuticals could have some therapeutic benefit for Duchenne Muscular Dystrophy (DMD). This review gathers and evaluates the peer-reviewed scientific studies that have used nutraceuticals in clinical or pre-clinical trials for DMD and thus separates the credible from the conjecture.

Phenolic Melatonin-Related Compounds: Their Role as Chemical Protectors against Oxidative Stress

There is currently no doubt about the serious threat that oxidative stress (OS) poses to human health. Therefore, a crucial strategy to maintain a good health status is to identify molecules capable of offering protection against OS through chemical routes. Based on the known efficiency of the phenolic and melatonin (MLT) families of compounds as antioxidants, it is logical to assume that phenolic MLT-related compounds should be (at least) equally efficient. Unfortunately, they have been less investigated than phenols, MLT and its non-phenolic metabolites in this context. The evidence reviewed here strongly suggests that MLT phenolic derivatives can act as both primary and secondary antioxidants, exerting their protection through diverse chemical routes. They all seem to be better free radical scavengers than MLT and Trolox, while some of them also surpass ascorbic acid and resveratrol. However, there are still many aspects that deserve further investigations for this kind of compounds.

Sleep Control, GPCRs, and Glucose Metabolism

Modern lifestyles prolong daily activities into the nighttime, disrupting circadian rhythms, which may cause sleep disturbances. Sleep disturbances have been implicated in the dysregulation of blood glucose levels and reported to increase the risk of type 2 diabetes (T2D) and diabetic complications. Sleep disorders are treated using anti-insomnia drugs that target ionotropic and G protein-coupled receptors (GPCRs), including γ-aminobutyric acid (GABA) agonists, melatonin agonists, and orexin receptor antagonists. A deeper understanding of the effects of these medications on glucose metabolism and their underlying mechanisms of action is crucial for the treatment of diabetic patients with sleep disorders. In this review we focus on the beneficial impact of sleep on glucose metabolism and suggest a possible strategy for therapeutic intervention against sleep-related metabolic disorders.

Melatonin prevents adverse myocardial infarction remodeling via Notch1/Mfn2 pathway

Mitochondrial dysfunction is linked with myocardial infarction (MI), a disorder in which Notch1 has attracted increasing attention. However, the involvement of Notch1 in mitochondrial impairment after an MI is poorly understood, as is the role of mitochondrial fusion-associated protein 2 (Mfn2). Moreover, whether melatonin potentiates the Notch1/Mfn2 pathway in post-MI cardiac damage remains unclear. In our study, small interfering RNAs against Notch1 or Mfn2 and Jagged1 peptide were delivered via intramyocardial injection. At 3 days after these treatments, MI was induced by ligation of the anterior descending branch. We found that this ablation of Notch1 or Mfn2 aggravated post-MI injury, including worsened mitochondrial damage and increased generation of reactive oxygen species (ROS). In contrast, Jagged1 improved mitochondrial structure and function, decreased ROS production and attenuated post-MI injury. Interestingly, though Mfn2 expression was mildly regulated by Notch1 signaling in myocardium, Mfn2 deficiency nearly eliminated the cardioprotection by Jagged1, as evidenced by suppressed cardiac function, aggravated myocardial fibrosis, increased cell apoptosis, worsened mitochondrial impairment and enhanced oxidative stress. These observations revealed that Mfn2 plays an indispensable role in protection against MI-induced injury by Notch1. The mechanism might involve disrupting a damaging cycle of mitochondrial damage and ROS generation. Furthermore, melatonin activated Notch1 signaling and increased Mfn2 expression were reversed by luzindole, a nonselective antagonist of the melatonin receptor. Notably, melatonin attenuated post-MI injury in normal mice, but not in mice deficient in Notch1 or Mfn2. These results demonstrate that melatonin attenuates post-MI injury via the Notch1/Mfn2 pathway in a receptor-dependent manner.

The antioxidative property of melatonin against brain ischemia

INTRODUCTION

This review briefly summarizes some of the large amount of data documenting the ability of melatonin to limit molecular and organ tissue damage in neural ischemia-reperfusion injury (stroke), where free radicals are generally considered as being responsible for much of the resulting tissue destruction.

AREA COVERED

Melatonin actions that have been identified include its ability to directly neutralize a number of toxic reactants and stimulate antioxidative enzymes. Furthermore, several of its metabolites such as N(1)-acetyl-N(2)-formyl-5- methoxykynuramine (AFMK) and N(1)-acetyl-5-methoxykynuramine (AMF), are themselves scavengers suggesting that there is a cascade of reactions that greatly increase the efficacy of melatonin. Expert Commentary: However, the mechanisms by which melatonin is protective in such widely diverse areas of the cell and different organs are likely not yet all identified.

Melatonin's role in preventing toxin-related and sepsis-mediated hepatic damage: A review

The liver is a central organ in detoxifying molecules and would otherwise cause molecular damage throughout the organism. Numerous toxic agents including aflatoxin, heavy metals, nicotine, carbon tetrachloride, thioacetamide, and toxins derived during septic processes, generate reactive oxygen species followed by molecular damage to lipids, proteins and DNA, which culminates in hepatic cell death. As a result, the identification of protective agents capable of ameliorating the damage at the cellular level is an urgent need. Melatonin is a powerful endogenous antioxidant produced by the pineal gland and a variety of other organs and many studies confirm its benefits against oxidative stress including lipid peroxidation, protein mutilation and molecular degeneration in various organs, including the liver. Recent studies confirm the benefits of melatonin in reducing the cellular damage generated as a result of the metabolism of toxic agents. These protective effects are apparent when melatonin is given as a sole therapy or in conjunction with other potentially protective agents. This review summarizes the published reports that document melatonin's ability to protect hepatocytes from molecular damage due to a wide variety of substances (aflatoxin, heavy metals, nicotine, carbon tetrachloride, chemotherapeutics, and endotoxins involved in the septic process), and explains the potential mechanisms by which melatonin provides these benefits. Melatonin is an endogenously-produced molecule which has a very high safety profile that should find utility as a protective molecule against a host of agents that are known to cause molecular mutilation at the level of the liver.

Beneficial effects of melatonin and alpha lipoic acid on lopinavir/ ritonavir-induced alterations in serum lipid and glucose levels of male albino rats

The use of lopinavir/ritonavir (LPV/r) has been associated with alterations in serum lipid and glucose levels. This study was designed to investigate the effects of melatonin (MT) and alpha lipoic acid (ALA) on LPV/r-induced changes in serum levels of triglycerides (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C) and glucose (GL) levels in male albino rats. Rats in group A1 (placebo control) and group A2 (solvent control) were orally treated with normal saline and 1% ethanol respectively. Groups B-F contained 15 rats each which were divided into 3 groups of 5 rats each. Rats in group B were orally treated with MT (10 mg kg-1/day), ALA (10 mg kg-1/day) and a combination of MT and ALA, accordingly. Rats in group C were orally treated with 22.9/5.71, 45.6/11.4 and 91.4/22.9 mg kg-1/day of LPV/r, accordingly. Rats in groups D-F were orally treated with MT (10 mg kg-1/ day), ALA (10 mg kg-1/day) and combined doses of ALA and MT before oral treatment with 22.9/5.71, 45.6/11.4 and 91.4/22.9 mg kg-1/day of LPV/r, accordingly. All rats were treated for 30 days and at the end of the drug treatment, the serum levels of lipid fractions and glucose were evaluated. Treatment with MT and ALA significantly (p<0.05) decreased baseline serum levels of TG, TC, VLDL-C, LDL-C and GL, but these parameters were significantly (p<0.05) increased in a dose-dependent manner in LPV/r-treated rats when compared to placebo control. Administration of MT and ALA prior to treatment with LPV/r significantly (p<0.05) decreased serum levels of TG, TC, VLDL-C, LDL-C and GL when compared to LPV/r-treated rats. However, decreases obtained in rats pretreated with combined doses of MT and ALA were significantly (p<0.05) different when compared to their individual doses. This study showed that MT and ALA can serve as remedies for LPV/r-induced alterations in serum lipid and glucose levels.

Permeabilized myocardial fibers as model to detect mitochondrial dysfunction during sepsis and melatonin effects without disruption of mitochondrial network

Analysis of mitochondrial function is crucial to understand their involvement in a given disease. High-resolution respirometry of permeabilized myocardial fibers in septic mice allows the evaluation of the bioenergetic system, maintaining mitochondrial ultrastructure and intracellular interactions, which are critical for an adequate functionality. OXPHOS and electron transport system (ETS) capacities were assessed using different substrate combinations. Our findings show a severe septic-dependent impairment in OXPHOS and ETS capacities with mitochondrial uncoupling at early and late phases of sepsis. Moreover, sepsis triggers complex III (CIII)-linked alterations in supercomplexes structure, and loss of mitochondrial density. In these conditions, melatonin administration to septic mice prevented sepsis-dependent mitochondrial injury in mitochondrial respiration. Likewise, melatonin improved cytochrome b content and ameliorated the assembly of CIII in supercomplexes. These results support the use of permeabilized fibers to identify properly the respiratory deficits and specific melatonin effects in sepsis.

Melatonin: A Potential Anti-Oxidant Therapeutic Agent for Mitochondrial Dysfunctions and Related Disorders

Mitochondria play a central role in cellular physiology. Besides their classic function of energy metabolism, mitochondria are involved in multiple cell functions, including energy distribution through the cell, energy/heat modulation, regulation of reactive oxygen species (ROS), calcium homeostasis, and control of apoptosis. Simultaneously, mitochondria are the main producer and target of ROS with the result that multiple mitochondrial diseases are related to ROS-induced mitochondrial injuries. Increased free radical generation, enhanced mitochondrial inducible nitric oxide synthase (iNOS) activity, enhanced nitric oxide (NO) production, decreased respiratory complex activity, impaired electron transport system, and opening of mitochondrial permeability transition pores have all been suggested as factors responsible for impaired mitochondrial function. Because of these, neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and aging, are caused by ROS-induced mitochondrial dysfunctions. Melatonin, the major hormone of the pineal gland, also acts as an anti-oxidant and as a regulator of mitochondrial bioenergetic function. Melatonin is selectively taken up by mitochondrial membranes, a function not shared by other anti-oxidants, and thus has emerged as a major potential therapeutic tool for treating neurodegenerative disorders. Multiple in vitro and in vivo experiments have shown the protective role of melatonin for preventing oxidative stress-induced mitochondrial dysfunction seen in experimental models of PD, AD, and HD. With these functions in mind, this article reviews the protective role of melatonin with mechanistic insights against mitochondrial diseases and suggests new avenues for safe and effective treatment modalities against these devastating neurodegenerative diseases. Future insights are also discussed.

Perspectives on the membrane fatty acid unsaturation/pacemaker hypotheses of metabolism and aging

The membrane pacemaker hypotheses of metabolism and aging are distinct, but interrelated hypotheses positing that increases in unsaturation of lipids within membranes are correlated with increasing basal metabolic rate and decreasing longevity, respectively. The two hypotheses each have evidence that either supports or contradicts them, but consensus has failed to emerge. In this review, we identify sources of weakness of previous studies supporting and contradicting these hypotheses and suggest different methods and lines of inquiry. The link between fatty acyl composition of membranes and membrane-bound protein activity is a central tenet of the membrane pacemaker hypothesis of metabolism, but the mechanism by which unsaturation would change protein activity is not well defined and, whereas fatty acid desaturases have been put forward by some as the mechanism behind evolutionary differences in fatty acyl composition of phospholipids among organisms, there have been no studies to differentiate whether desaturases have been more affected by natural selection on aging and metabolic rate than have elongases or acyltransferases. Past analyses have been hampered by potentially incorrect estimates of the peroxidizability of lipids and longevity of study animals, and by the confounding effect of phylogeny. According to some authors, body mass may also be a confounding effect that should be taken into account, though this is not universally accepted. Further research on this subject should focus more on mechanisms and take weaknesses of past studies into account.

Melatonin ameliorates amyloid beta-induced memory deficits, tau hyperphosphorylation and neurodegeneration via PI3/Akt/GSk3β pathway in the mouse hippocampus

Alzheimer's disease (AD) is the most prevalent age-related neurodegenerative disease, pathologically characterized by the accumulation of amyloid beta (Aβ) aggregation in the brain, and is considered to be the primary cause of cognitive dysfunction. Aβ aggregates lead to synaptic disorder, tau hyperphosphorylation, and neurodegeneration. In this study, the underlying neuroprotective mechanism of melatonin against Aβ1-42-induced neurotoxicity was investigated in the mice hippocampus. Intracerebroventricular (i.c.v.) Aβ1-42-injection triggered memory impairment, synaptic disorder, hyperphosphorylation of tau protein, and neurodegeneration in the mice hippocampus. After 24 hr of Aβ1-42 injection, the mice were treated with melatonin (10 mg/kg, intraperitonially) for 3 wks, reversed the Aβ1-42-induced synaptic disorder via increasing the level of presyanptic (Synaptophysin and SNAP-25) and postsynaptic protein [PSD95, p-GluR1 (Ser845), SNAP23, and p-CREB (Ser133)], respectively, and attenuated the Aβ1-42-induced memory impairment. Chronic melatonin treatment attenuated the hyperphosphorylation of tau protein via PI3K/Akt/GSK3β signaling by activating the p-PI3K, p-Akt (Ser 473) and p-GSK3β (Ser9) in the Aβ1-42-treated mice. Furthermore, melatonin decreased Aβ1-42 -induced apoptosis through decreasing the overexpression of caspase-9, caspase-3, and PARP-1 level. Additionally, the evaluation of immunohistochemical analysis of caspase-3, Fluorojade-B, and Nissl staining indicated that melatonin prevented neurodegeneration in Aβ1-42-treated mice. Our results demonstrated that melatonin has neuroprotective effect against Aβ1-42-induced neurotoxicity through decreasing memory impairment, synaptic disorder, tau hyperphosphorylation, and neurodegeneration via PI3K/Akt/GSK3β signaling in the Aβ1-42-treated mouse model of AD. On the basis of these results, we suggest that melatonin could be an effective, promising, and safe neuroprotective candidate for the treatment of progressive neurodegenerative disorders, such as AD.

C-phycocyanin prevents cisplatin-induced mitochondrial dysfunction and oxidative stress

The potential of C-phycocyanin (C-PC) to prevent cisplatin (CP)-induced kidney mitochondrial dysfunction was determined in CD-1 male mice. The CP-induced mitochondrial dysfunction was characterized by ultrastructural abnormalities and by decrease in the following parameters in isolated kidney mitochondria: adenosine diphosphate (ADP)-induced oxygen consumption (state 3), respiratory control ratio, ADP/oxygen (ADP/O) ratio, adenosine triphosphate synthesis, membrane potential, calcium retention, glutathione (GSH) content, and activity of respiratory complex I, aconitase, catalase, and GSH peroxidase. These mitochondria also showed increase in hydrogen peroxide production, malondialdehyde, and 3-nitrotyrosine protein adducts content. The above-described changes, as well as CP-induced nephrotoxicity, were attenuated in mice pretreated with a single injection of C-PC. Our data suggest that the attenuation of mitochondrial abnormalities is involved in the protective effect of C-PC against CP-induced nephrotoxicity. This is the first demonstration that C-PC pretreatment prevents CP-induced mitochondrial dysfunction in mice.

Mechanisms of isoproterenol-induced cardiac mitochondrial damage: protective actions of melatonin

Mitochondrial dysfunction due to oxidative damage is the key feature of several diseases. We have earlier reported mitochondrial damage resulting from the generation of oxidative stress as a major pathophysiological effect of isoproterenol (ISO)-induced myocardial ischemia in rats. That melatonin is an antioxidant that ameliorates oxidative stress in experimental animals as well as in humans is well established. We previously demonstrated that melatonin provides cardioprotection against ISO-induced myocardial injury as a result of its antioxidant properties. The mechanism of ISO-induced cardiac mitochondrial damage and protection by melatonin, however, remains to be elucidated in vitro. In this study, we provide evidence that ISO causes dysfunction of isolated goat heart mitochondria. Incubation of cardiac mitochondria with increasing concentrations of ISO decreased mitochondrial succinate dehydrogenase (SDH) activity, which plays a pivotal role in mitochondrial bioenergetics, as well as altered the activities of other key enzymes of the Kreb's cycle and the respiratory chain. Co-incubation of ISO-challenged mitochondria with melatonin prevented the alterations in enzyme activity. That these changes in mitochondrial energy metabolism were due to the perpetration of oxidative stress by ISO was evident from the increased levels of lipid peroxidation and decreased reduced glutathione/oxidized glutathione ratio. ISO-induced oxidative stress also altered mitochondrial redox potential and brought about changes in the activity of the antioxidant enzymes manganese superoxide dismutase and glutathione peroxidase, eventually leading to alterations in total ATPase activity and membrane potential. Melatonin ameliorated these changes likely through its antioxidant abilities suggesting a possible mechanism of cardioprotection by this indole against ISO-induced myocardial injury.

Neuroendocrine control of photoperiodic changes in immune function

Seasonal variation in immune function putatively maximizes survival and reproductive success. Day length (photoperiod) is the most potent signal for time of year. Animals typically organize breeding, growth, and behavior to adapt to spatial and temporal niches. Outside the tropics individuals monitor photoperiod to support adaptations favoring survival and reproductive success. Changes in day length allow anticipation of seasonal changes in temperature and food availability that are critical for reproductive success. Immune function is typically bolstered during winter, whereas reproduction and growth are favored during summer. We provide an overview of how photoperiod influences neuronal function and melatonin secretion, how melatonin acts directly and indirectly to govern seasonal changes in immune function, and the manner by which other neuroendocrine effectors such as glucocorticoids, prolactin, thyroid, and sex steroid hormones modulate seasonal variations in immune function. Potential future research avenues include commensal gut microbiota and light pollution influences on photoperiodic responses.

Caloric restriction, resveratrol and melatonin: Role of SIRT1 and implications for aging and related-diseases

Aging is an inevitable and multifactorial biological process. Free radicals have been implicated in aging processes; it is hypothesized that they cause cumulative oxidative damage to crucial macromolecules and are responsible for failure of multiple physiological mechanisms. However, recent investigations have also suggested that free radicals can act as modulators of several signaling pathways such as those related to sirtuins. Caloric restriction is a non-genetic manipulation that extends lifespan of several species and improves healthspan; the belief that many of these benefits are due to the induction of sirtuins has led to the search for sirtuin activators, especially sirtuin 1, the most studied. Resveratrol, a polyphenol found in red grapes, was first known for its antioxidant and antifungal properties, and subsequently has been reported several biological effects, including the activation of sirtuins. Endogenously-produced melatonin, a powerful free radical scavenger, declines with age and its loss contributes to degenerative conditions of aging. Recently, it was reported that melatonin also activates sirtuins, in addition to other functions, such as regulator of circadian rhythms or anti-inflammatory properties. The fact that melatonin and resveratrol are present in various foods, exhibiting possible synergistic effects, suggests the use of dietary ingredients to promote health and longevity.

The protective effect of melatonin on neural stem cell against LPS-induced inflammation

Stem cell therapy for tissue regeneration has several limitations in the fact that transplanted cells could not survive for a long time. For solving these limitations, many studies have focused on the antioxidants to increase survival rate of neural stem cells (NSCs). Melatonin, an antioxidant synthesized in the pineal gland, plays multiple roles in various physiological mechanisms. Melatonin exerts neuroprotective effects in the central nervous system. To determine the effect of melatonin on NSCs which is in LPS-induced inflammatory stress state, we first investigated nitric oxide (NO) production and cytotoxicity using Griess reagent assays, LDH assay, and neurosphere counting. Also, we investigated the effect of melatonin on NSCs by measuring the mRNA levels of SOX2, TLX, and FGFR-2. In addition, western blot analyses were performed to examine the activation of PI3K/Akt/Nrf2 signaling in LPS-treated NSCs. In the present study, we suggested that melatonin inhibits NO production and protects NSCs against LPS-induced inflammatory stress. In addition, melatonin promoted the expression of SOX2 and activated the PI3K/Akt/Nrf2 signaling under LPS-induced inflammation condition. Based on our results, we conclude that melatonin may be an important factor for the survival and proliferation of NSCs in neuroinflammatory diseases.

New antioxidant drugs for neonatal brain injury

The brain injury concept covers a lot of heterogeneity in terms of aetiology involving multiple factors, genetic, hemodynamic, metabolic, nutritional, endocrinological, toxic, and infectious mechanisms, acting in antenatal or postnatal period. Increased vulnerability of the immature brain to oxidative stress is documented because of the limited capacity of antioxidant enzymes and the high free radicals (FRs) generation in rapidly growing tissue. FRs impair transmembrane enzyme Na⁺/K⁺-ATPase activity resulting in persistent membrane depolarization and excessive release of FR and excitatory aminoacid glutamate. Besides being neurotoxic, glutamate is also toxic to oligodendroglia, via FR effects. Neuronal cells die of oxidative stress. Excess of free iron and deficient iron/binding metabolising capacity are additional features favouring oxidative stress in newborn. Each step in the oxidative injury cascade has become a potential target for neuroprotective intervention. The administration of antioxidants for suspected or proven brain injury is still not accepted for clinical use due to uncertain beneficial effects when treatments are started after resuscitation of an asphyxiated newborn. The challenge for the future is the early identification of high-risk babies to target a safe and not toxic antioxidant therapy in combination with standard therapies to prevent brain injury and long-term neurodevelopmental impairment.

Use of melatonin as an adjuvant therapy in neonatal sepsis

OBJECTIVE

The objective of this study is to evaluate the therapeutic efficacy of melatonin as an adjuvant therapy in treating neonatal sepsis.

PATIENTS AND METHODS

A prospective clinical trial study was conducted on 50 infants with neonatal sepsis diagnosed on the basis of both clinical and laboratory criteria. Enrolled infants were divided into two groups. Intervention group (n = 25) received melatonin and antibiotics, while the control group (n = 25) was treated with antibiotics only. Melatonin was administered as a single oral dose of 20 mg and antibiotics were administered according to a standard protocol. Both groups were compared using a predefined sepsis score utilizing both clinical and laboratory parameters.

RESULTS

There was no significant difference in sepsis score between both groups before starting melatonin (p-value = 0.99), while there was significant difference in sepsis score between groups after 24 hours, 48 hours and 72 hours of starting melatonin with (p-value = 0.008, 0.006 and 0.002, respectively). There was significant improvement sepsis score in both groups with more improvement of sepsis score in the intervention group.

CONCLUSION

Administration of melatonin as an adjuvant therapy in the treatment of neonatal sepsis is associated with improvement of clinical and laboratory outcomes.

Melatonin attenuates D-galactose-induced memory impairment, neuroinflammation and neurodegeneration via RAGE/NF-K B/JNK signaling pathway in aging mouse model

Melatonin acts as a pleiotropic agent in various age-related neurodegenerative diseases. In this study, we examined the underlying neuroprotective mechanism of melatonin against D-galactose-induced memory and synaptic dysfunction, elevated reactive oxygen species (ROS), neuroinflammation and neurodegeneration. D-galactose was administered (100 mg/kg intraperitoneally (i.p.)) for 60 days. After 30 days of D-galactose administration, vehicle (same volume) or melatonin (10 mg/kg, i.p.) was administered for 30 days. Our behavioral (Morris water maze and Y-maze test) results revealed that chronic melatonin treatment alleviated D-galactose-induced memory impairment. Additionally, melatonin treatment reversed D-galactose-induced synaptic disorder via increasing the level of memory-related pre-and postsynaptic protein markers. We also determined that melatonin enhances memory function in the D-galactose-treated mice possibly via reduction of elevated ROS and receptor for advanced glycation end products (RAGE). Furthermore, Western blot and morphological results showed that melatonin treatment significantly reduced D-galactose-induced neuroinflammation through inhibition of microgliosis (Iba-1) and astrocytosis (GFAP), and downregulating other inflammatory mediators such as p-IKKβ, p-NF-K B65, COX2, NOS2, IL-1β, and TNFα. Moreover, melatonin lowered the oxidative stress kinase p-JNK which suppressed various apoptotic markers, that is, cytochrome C, caspase-9, caspase-3 and PARP-1, and prevent neurodegeneration. Hence, melatonin attenuated the D-galactose-induced memory impairment, neuroinflammation and neurodegeneration possibly through RAGE/NF-K B/JNK pathway. Taken together, our data suggest that melatonin could be a promising, safe and endogenous compatible antioxidant candidate for age-related neurodegenerative diseases such as Alzheimer's disease (AD).

Protecting the melatonin rhythm through circadian healthy light exposure

Currently, in developed countries, nights are excessively illuminated (light at night), whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs) and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system.

Attenuation of ultraviolet A-induced alterations in NIH3T3 dermal fibroblasts by melatonin

BACKGROUND

Sun exposure is responsible for long-term clinical skin changes such as photoageing, photodamage and photocancers. Ultraviolet (UV)A wavelengths stimulate the production of reactive oxygen species (ROS) that may contribute to photoageing. To protect against oxidative stress, skin cells have developed several defence systems, including ROS and metal ion scavengers and a battery of detoxifying, haem-degrading and repair enzymes. Melatonin's antioxidant activity is the result of three different but complementary actions: (i) a direct action due to its ability to act as a free radical scavenger; (ii) an indirect action that is a consequence of melatonin's ability to reduce free radical generation (radical avoidance); and (iii) its ability to upregulate antioxidant enzymes.

OBJECTIVES

In this study, we focused our attention on the prevention of photodamage, choosing melatonin as an antioxidant agent.

METHODS

In the present study we analysed the effects of pretreatment of murine fibroblasts cells (NIH3T3) with melatonin (1 mmol L(-1) ) followed by UVA irradiation (15 J cm(-2) ). Thereafter, changes in components of the extracellular matrix and in some antioxidant enzymes (inducible and constitutive haem oxygenase) were evaluated.

RESULTS

We observed that UVA radiation caused altered expression of extracellular matrix proteins and induced the expression of inducible haem oxygenase. This increase was not sufficient to protect the cells from damage. Instead, melatonin pretreatment led to increased expression of haem-degrading enzymes and suppression of UVA-induced photodamage.

CONCLUSIONS

These results suggest that melatonin, as a modifier of the dermatoendocrine system, may have utility in reducing the effects of skin ageing.

Mitochondrial catastrophe during doxorubicin-induced cardiotoxicity: a review of the protective role of melatonin

Anthracyclines, such as doxorubicin, are among the most valuable treatments for various cancers, but their clinical use is limited due to detrimental side effects such as cardiotoxicity. Doxorubicin-induced cardiotoxicity is emerging as a critical issue among cancer survivors and is an area of much significance to the field of cardio-oncology. Abnormalities in mitochondrial functions such as defects in the respiratory chain, decreased adenosine triphosphate production, mitochondrial DNA damage, modulation of mitochondrial sirtuin activity and free radical formation have all been suggested as the primary causative factors in the pathogenesis of doxorubicin-induced cardiotoxicity. Melatonin is a potent antioxidant, is nontoxic, and has been shown to influence mitochondrial homeostasis and function. Although a number of studies support the mitochondrial protective role of melatonin, the exact mechanisms by which melatonin confers mitochondrial protection in the context of doxorubicin-induced cardiotoxicity remain to be elucidated. This review focuses on the role of melatonin on doxorubicin-induced bioenergetic failure, free radical generation, and cell death. A further aim is to highlight other mitochondrial parameters such as mitophagy, autophagy, mitochondrial fission and fusion, and mitochondrial sirtuin activity, which lack evidence to support the role of melatonin in the context of cardiotoxicity.

Melatonin protects the integrity of granulosa cells by reducing oxidative stress in nuclei, mitochondria, and plasma membranes in mice

Melatonin protects luteinized granulosa cells (GCs) from oxidative stress in the follicle during ovulation. However, it is unclear in which cellular components (e.g., nuclei, mitochondria, or plasma membranes) melatonin works as an antioxidant. GCs from immature (3 wks) ICR mice were incubated with hydrogen peroxide (H2O2; 0.01, 0.1, 1, 10 mM) in the presence or absence of melatonin (100 μg/ml) for 2 h. DNA damage was assessed by fluorescence-based immunocytochemistry using specific antibodies for 8-hydroxydeoxyguanosine (8-OHdG), an indicator of oxidative guanine base damage in DNA, and for histone H2AX phosphorylation (γH2AX), a marker of double-strand breaks of DNA. Mitochondrial function was assessed by the fluorescence intensity of MitoTracker Red probes, which diffuse across the membrane and accumulate in mitochondria with active membrane potentials. Lipid peroxidation of plasma membranes was analyzed by measuring hexanoyl-lysine (HEL), a oxidative stress marker for lipid peroxidation. Apoptosis of GCs was assessed by nuclear fragmentation using DAPI staining, and apoptotic activities were evaluated by caspase-3/7 activities. H2O2 treatment significantly increased the fluorescence intensities of 8-OHdG and γH2AX, reduced the intensity of MitoTracker Red in the mitochondria, increased HEL concentrations in GCs, and enhanced the number of apoptotic cells and caspase-3/7 activities. All these changes were significantly decreased by melatonin treatment. Melatonin reduced oxidative stress-induced DNA damage, mitochondrial dysfunction, lipid peroxidation, and apoptosis in GCs, suggesting that melatonin protects GCs by reducing oxidative stress of cellular components including nuclei, mitochondria, and plasma membranes. Melatonin helps to maintain the integrity of GCs as an antioxidant in the preovulatory follicle.

Mitochondrial and metabolic dysfunction in renal convoluted tubules of obese mice: protective role of melatonin

Obesity is a common and complex health problem, which impacts crucial organs; it is also considered an independent risk factor for chronic kidney disease. Few studies have analyzed the consequence of obesity in the renal proximal convoluted tubules, which are the major tubules involved in reabsorptive processes. For optimal performance of the kidney, energy is primarily provided by mitochondria. Melatonin, an indoleamine and antioxidant, has been identified in mitochondria, and there is considerable evidence regarding its essential role in the prevention of oxidative mitochondrial damage. In this study we evaluated the mechanism(s) of mitochondrial alterations in an animal model of obesity (ob/ob mice) and describe the beneficial effects of melatonin treatment on mitochondrial morphology and dynamics as influenced by mitofusin-2 and the intrinsic apoptotic cascade. Melatonin dissolved in 1% ethanol was added to the drinking water from postnatal week 5–13; the calculated dose of melatonin intake was 100 mg/kg body weight/day. Compared to control mice, obesity-related morphological alterations were apparent in the proximal tubules which contained round mitochondria with irregular, short cristae and cells with elevated apoptotic index. Melatonin supplementation in obese mice changed mitochondria shape and cristae organization of proximal tubules, enhanced mitofusin-2 expression, which in turn modulated the progression of the mitochondria-driven intrinsic apoptotic pathway. These changes possibly aid in reducing renal failure. The melatonin-mediated changes indicate its potential protective use against renal morphological damage and dysfunction associated with obesity and metabolic disease.

Oxidative stress, cardiolipin and mitochondrial dysfunction in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is today considered the most common form of chronic liver disease, affecting a high proportion of the population worldwide. NAFLD encompasses a large spectrum of liver damage, ranging from simple steatosis to steatohepatitis, advanced fibrosis and cirrhosis. Obesity, hyperglycemia, type 2 diabetes and hypertriglyceridemia are the most important risk factors. The pathogenesis of NAFLD and its progression to fibrosis and chronic liver disease is still unknown. Accumulating evidence indicates that mitochondrial dysfunction plays a key role in the physiopathology of NAFLD, although the mechanisms underlying this dysfunction are still unclear. Oxidative stress is considered an important factor in producing lethal hepatocyte injury associated with NAFLD. Mitochondrial respiratory chain is the main subcellular source of reactive oxygen species (ROS), which may damage mitochondrial proteins, lipids and mitochondrial DNA. Cardiolipin, a phospholipid located at the level of the inner mitochondrial membrane, plays an important role in several reactions and processes involved in mitochondrial bioenergetics as well as in mitochondrial dependent steps of apoptosis. This phospholipid is particularly susceptible to ROS attack. Cardiolipin peroxidation has been associated with mitochondrial dysfunction in multiple tissues in several physiopathological conditions, including NAFLD. In this review, we focus on the potential roles played by oxidative stress and cardiolipin alterations in mitochondrial dysfunction associated with NAFLD.

Beneficial effects of melatonin on bovine oocytes maturation: a mechanistic approach

This study was performed to investigate the effect of melatonin on bovine oocyte maturation and subsequent embryonic development in vitro. The endogenous melatonin concentration in bovine follicular fluid is approximately 10(-11) M. To examine the potential beneficial effects of melatonin on bovine oocyte maturation in vitro, germinal vesicle (GV) oocytes were incubated with different concentrations of melatonin (10(-11), 10(-9), 10(-7), 10(-5), 10(-3) M). Melatonin supplementation at suitable concentrations significantly promoted oocyte maturation. The development of embryos and the mean cell number/blastocyst produced after in vitro fertilization were remarkably improved. The most effective melatonin concentrations obtained from the studies ranged from 10(-9) to 10(-7) M. The expression of melatonin receptor MT1 and MT2 genes was identified in cumulus cells, granulosa cells, and oocytes using reverse transcription PCR, immunofluorescence, and Western blot. The mechanistic studies show that the beneficial effects of melatonin on bovine oocyte maturation are mediated via melatonin membrane receptors as the melatonin receptor agonist (IIK7) promotes this effect while the melatonin receptor antagonist (luzindole) blocks this action. Mechanistic explorations revealed that melatonin supplementation during bovine oocyte maturation significantly up-regulated the expressions of oocyte maturation-associated genes (GDF9, MARF1, and DNMT1a) and cumulus cells expansion-related gene (PTX3, HAS1/2) and that LHR1/2, EGFR are involved in signal transduction and epigenetic reprogramming. The results obtained from the studies provide new information regarding the mechanisms by which melatonin promotes bovine oocyte maturation in vitro and provide an important reference for in vitro embryo production of bovine and the human-assisted reproductive technology.

Local melatoninergic system as the protector of skin integrity

The human skin is not only a target for the protective actions of melatonin, but also a site of melatonin synthesis and metabolism, suggesting an important role for a local melatoninergic system in protection against ultraviolet radiation (UVR) induced damages. While melatonin exerts many effects on cell physiology and tissue homeostasis via membrane bound melatonin receptors, the strong protective effects of melatonin against the UVR-induced skin damage including DNA repair/protection seen at its high (pharmocological) concentrations indicate that these are mainly mediated through receptor-independent mechanisms or perhaps through activation of putative melatonin nuclear receptors. The destructive effects of the UVR are significantly counteracted or modulated by melatonin in the context of a complex intracutaneous melatoninergic anti-oxidative system with UVR-enhanced or UVR-independent melatonin metabolites. Therefore, endogenous intracutaneous melatonin production, together with topically-applied exogenous melatonin or metabolites would be expected to represent one of the most potent anti-oxidative defense systems against the UV-induced damage to the skin. In summary, we propose that melatonin can be exploited therapeutically as a protective agent or as a survival factor with anti-genotoxic properties or as a “guardian” of the genome and cellular integrity with clinical applications in UVR-induced pathology that includes carcinogenesis and skin aging.

Melatonin improves mitochondrial function in inguinal white adipose tissue of Zücker diabetic fatty rats

Mitochondrial dysfunction in adipose tissue may contribute to obesity-related metabolic derangements such as type 2 diabetes mellitus (T2DM). Because mitochondria are a target for melatonin action, the goal of this study was to investigate the effects of melatonin on mitochondrial function in white (WAT) and beige inguinal adipose tissue of Zücker diabetic fatty (ZDF) rats, a model of obesity-related T2DM. In this experimental model, melatonin reduces obesity and improves the metabolic profile. At 6 wk of age, ZDF rats and lean littermates (ZL) were subdivided into two groups, each composed of four rats: control (C-ZDF and C-ZL) and treated with oral melatonin in the drinking water (10 mg/kg/day) for 6 wk (M-ZDF and M-ZL). After the treatment period, animals were sacrificed, tissues dissected, and mitochondrial function assessed in isolated organelles. Melatonin increased the respiratory control ratio (RCR) in mitochondria from white fat of both lean (by 26.5%, P < 0.01) and obese (by 34.5%, P < 0.01) rats mainly through a reduction of proton leaking component of respiration (state 4) (28% decrease in ZL, P < 0.01 and 35% in ZDF, P < 0.01). However, melatonin treatment lowered the RCR in beige mitochondria of both lean (by 7%, P < 0.05) and obese (by 13%, P < 0.05) rats by maintaining high rates of uncoupled respiration. Melatonin also lowered mitochondrial oxidative status by reducing nitrite levels and by increasing superoxide dismutase activity. Moreover, melatonin treatment also caused a profound inhibition of Ca-induced opening of mPTP in isolated mitochondria from both types of fat, white and beige, in both lean and obese rats. These results demonstrate that chronic oral melatonin improves mitochondrial respiration and reduces the oxidative status and susceptibility to apoptosis in white and beige adipocytes. These melatonin effects help to prevent mitochondrial dysfunction and thereby to improve obesity-related metabolic disorders such as diabetes and dyslipidemia of ZDF rats.

Melatonin reduces cardiac morbidity and markers of myocardial ischemia after elective abdominal aortic aneurism repair: a randomized, placebo-controlled, clinical trial

The aim was to examine the effect of perioperative melatonin treatment on clinical cardiac morbidity and markers of myocardial ischemia in patients undergoing elective surgery for abdominal aortic aneurism. Reperfusion injury results in increased cardiac morbidity in patients undergoing surgery for abdominal aortic aneurisms (AAA). A randomized, placebo-controlled, clinical trial including patients undergoing surgery for AAA was performed. The patients received by infusion over a 2-hr period either, 50 mg melatonin or placebo intra-operatively, and 10 mg melatonin or placebo orally, the first three nights after surgery. Postoperative cardiac morbidity was registered, and blood samples for analysis of troponin-I (TpI) were collected preoperatively, and at 5 min, 6, 24, 48, 72, and 96 hr after clamp removal/recirculation of the first leg. Continuous measurement of ST-segment depression was performed by Holter monitoring. A total of 26 patients received melatonin, while 24 received placebo. A significant reduction in cardiac morbidity was seen in the melatonin-treated patients compared with those given placebo [4% versus 29% (P = 0.02)]. Five patients (19%) who received melatonin had increased TpI levels in the postoperative period compared with 12 patients (50%) who were given placebo (P = 0.036). The median number of ST-segment deviations was less in the melatonin-treated patients compared with the placebo group [median 1 (range 0-4) versus 6 (range 0-13) (P = 0.01)], but no differences were found in the duration of ST-segment deviations. Melatonin treatment in the perioperative period decreased clinical cardiac morbidity as well as the occurrence of myocardial ischemia after abdominal aortic aneurism repair.

Melatonin rescues 3T3-L1 adipocytes from FFA-induced insulin resistance by inhibiting phosphorylation of IRS-1 on Ser307

Melatonin is biosynthesized in the pineal gland and secreted into the bloodstream. Evidences indicate a role of melatonin in the regulation of glucose metabolism. The objective of this study was to investigate the effect of melatonin on insulin sensitivity in insulin resistant adipocytes. Following a preincubation with melatonin or vehicle for 30 min, insulin resistant cells of 3T3-L1 adipocytes were induced by palmitic acids (300 μM, 6 h). Our results showed that palmitic acids inhibited both the basal and insulin-stimulated uptake of [(3)H]-2-Deoxyglucose, down-regulated the levels of IRS-1 and GLUT-4. However, compared to the vehicle group, melatonin pre-treatment increased significantly the uptake of [(3)H]-2-Deoxyglucose as well as the level of GLUT-4, and decreased phosphorylated IRS-1 (Ser307) although total IRS-1 did not change significantly. These data suggest that palmitic acids impair insulin signal via down-regulating the expressions of IRS-1 and GLUT-4; whereas melatonin can ameliorate insulin sensitivity by inhibiting Ser307 phosphorylation in IRS-1 and increasing GLUT-4 expressions in insulin resistant 3T3-L1 adipocytes. We conclude that melatonin regulates the insulin sensitivity and glucose homeostasis via inhibiting Ser-phosphorylation and improving function of IRS-1.

Melatonin prevents chemical-induced haemopoietic cell death

Melatonin (MEL), a methoxyindole synthesized by the pineal gland, is a powerful antioxidant in tissues as well as within cells, with a fundamental role in ameliorating homeostasis in a number of specific pathologies. It acts both as a direct radical scavenger and by stimulating production/activity of intracellular antioxidant enzymes. In this work, some chemical triggers, with different mechanisms of action, have been chosen to induce cell death in U937 hematopoietic cell line. Cells were pre-treated with 100 µM MEL and then exposed to hydrogen peroxide or staurosporine. Morphological analyses, TUNEL reaction and Orange/PI double staining have been used to recognize ultrastructural apoptotic patterns and to evaluate DNA behavior. Chemical damage and potential MEL anti-apoptotic effects were quantified by means of Tali® Image-Based Cytometer, able to monitor cell viability and apoptotic events. After trigger exposure, chromatin condensation, micronuclei formation and DNA fragmentation have been observed, all suggesting apoptotic cell death. These events underwent a statistically significant decrease in samples pre-treated with MEL. After caspase inhibition and subsequent assessment of cell viability, we demonstrated that apoptosis occurs, at least in part, through the mitochondrial pathway and that MEL interacts at this level to rescue U937 cells from death.

Effect of melatonin on motor performance and brain cortex mitochondrial function during ethanol hangover

Increased reactive oxygen species generation and mitochondrial dysfunction occur during ethanol hangover. The aim of this work was to study the effect of melatonin pretreatment on motor performance and mitochondrial function during ethanol hangover. Male mice received melatonin solution or its vehicle in drinking water during 7 days and i.p. injection with EtOH (3.8 g/kg BW) or saline at the eighth day. Motor performance and mitochondrial function were evaluated at the onset of hangover (6h after injection). Melatonin improved motor coordination in ethanol hangover mice. Malate-glutamate-dependent oxygen uptake was decreased by ethanol hangover treatment and partially prevented by melatonin pretreatment. Melatonin alone induced a decrease of 30% in state 4 succinate-dependent respiratory rate. Also, the activity of the respiratory complexes was decreased in melatonin-pretreated ethanol hangover group. Melatonin pretreatment before the hangover prevented mitochondrial membrane potential collapse and induced a 79% decrement of hydrogen peroxide production as compared with ethanol hangover group. Ethanol hangover induced a 25% decrease in NO production. Melatonin alone and as a pretreatment before ethanol hangover significantly increased NO production by nNOS and iNOS as compared with control groups. No differences were observed in nNOS protein expression, while iNOS expression was increased in the melatonin group. Increased NO production by melatonin could be involved in the decrease of succinate-dependent oxygen consumption and the inhibition of complex IV observed in our study. Melatonin seems to act as an antioxidant agent in the ethanol hangover condition but also exhibited some dual effects related to NO metabolism.

Physiological underpinnings associated with differences in pace of life and metabolic rate in north temperate and neotropical birds

Animal life-history traits fall within limited ecological space with animals that have high reproductive rates having short lives, a continuum referred to as a "slow-fast" life-history axis. Animals of the same body mass at the slow end of the life-history continuum are characterized by low annual reproductive output and low mortality rate, such as is found in many tropical birds, whereas at the fast end, rates of reproduction and mortality are high, as in temperate birds. These differences in life-history traits are thought to result from trade-offs between investment in reproduction or self-maintenance as mediated by the biotic and abiotic environment. Thus, tropical and temperate birds provide a unique system to examine physiological consequences of life-history trade-offs at opposing ends of the "pace of life" spectrum. We have explored the implications of these trade-offs at several levels of physiological organization including whole-animal, organ systems, and cells. Tropical birds tend to have higher survival, slower growth, lower rates of whole-animal basal metabolic rate and peak metabolic rate, and smaller metabolically active organs compared with temperate birds. At the cellular level, primary dermal fibroblasts from tropical birds tend to have lower cellular metabolic rates and appear to be more resistant to oxidative cell stress than those of temperate birds. However, at the subcellular level, lipid peroxidation rates, a measure of the ability of lipid molecules within the cell membranes to thwart the propagation of oxidative damage, appear not to be different between tropical and temperate species. Nevertheless, lipids in mitochondrial membranes of tropical birds tend to have increased concentrations of plasmalogens (phospholipids with antioxidant properties), and decreased concentrations of cardiolipin (a complex phospholipid in the electron transport chain) compared with temperate birds.

Melatonin combined with endoplasmic reticulum stress induces cell death via the PI3K/Akt/mTOR pathway in B16F10 melanoma cells

This study investigated B16F10 melanoma cell death induced by melatonin combined with endoplasmic reticulum (ER) stress through the PI3K/Akt/mTOR pathway. Cell viability was significantly decreased after treatment with melatonin combined with ER stress from thapsigargin or tunicamycin compared to no treatment or treatment with melatonin only. Combined melatonin and ER stress also significantly reduced expression of p85β, p-Akt (Ser473, Thr308), and p-mTOR (Ser2448, Ser2481) compared to treatment with melatonin only. The ER stress protein p-PERK and p-eIF2α were significantly increased under combined melatonin and ER stress treatment compared to no treatment or treatment with melatonin only. Combined melatonin and ER stress significantly reduced Bcl-2 protein and augmented Bax protein compared to melatonin-only treatment. Also, the combined treatment significantly lowered expression of catalase, Cu/Zn-SOD, and Mn-SOD proteins compared to melatonin only. Expression of p85β was significantly more decreased under treatment with melatonin and thapsigargin or tunicamycin plus the PI3K inhibitors LY294002 or wortmannin than under treatment with only melatonin or a PI3K inhibitor. The PI3K downstream target p-Akt (Ser473, Thr308) showed significantly decreased expression under treatment with melatonin and thapsigargin or tunicamycin plus PI3K inhibitors than under treatment with melatonin or PI3K inhibitors only. These results indicate that survival of B16F10 melanoma cells after combined treatment with melatonin and ER stress inducers is suppressed through regulation of the PI3K/Akt/mTOR pathway. Melatonin combined with thapsigargin or tunicamycin appears to be a promising strategy for effective melanoma treatment.

Novel therapeutic strategies for traumatic brain injury: acute antioxidant reinforcement

Traumatic brain injury (TBI) is the most important cause of disability in individuals under the age of 45 years and thus represents a significant social and economic burden. Evidence strongly suggests that oxidative stress is a cornerstone event leading to and propagating secondary injury mechanisms such as excitotoxicity, mitochondrial dysfunction, apoptosis, autophagy, brain edema, and inflammation. TBI has defied conventional approaches to diagnosis and therapy development because of its heterogeneity and complexity. Therefore, it is necessary to explore alternative approaches to therapy development for TBI. The aim of this review is to present a therapeutic approach for TBI, taking into account the evidence supporting the role for oxidative stress in the pathophysiological processes of secondary brain injury. The role of agents such as mitochondria-targeted antioxidants (melatonin and new mitochondria-targeted antioxidants), nicotinamide adenine dinucleotide phosphate (NADPH) inhibitors (antioxidant vitamins and apocynin), and other compounds having mainly antioxidant properties (hydrogen-rich saline, sulforaphane, U-83836E, omega-3, and polyphenols) is covered. The rationale for innovative antioxidant therapies based on current knowledge and particularly the most recent studies regarding this field is discussed. Particular considerations and translational potential of new TBI treatments are examined and a novel therapeutic proposal for TBI is presented.

Age-related changes in mitochondrial function of mouse colonic smooth muscle: beneficial effects of melatonin

Aging is a multifactorial process that involves biochemical, structural, and functional changes in mitochondria. The ability of melatonin to palliate the alterations induced by aging is based on its chronobiologic, antioxidant, and mitochondrial effects. There is little information about the effects of melatonin on the in situ mitochondrial network of aging cells and its physiological implications. We have studied the ability of melatonin to prevent the functional alterations of in situ mitochondria of smooth muscle cells and its impact on contractility. Mitochondrial membrane potential was recorded in isolated colonic smooth muscle cells from young mice (3 month old), aged mice (22-24-month old), and aged mice treated with melatonin (starting at 14-month age). Aging induced a partial mitochondrial depolarization in resting conditions and reduced the depolarizing response to cellular stimulation. Use of oligomycin indicated that aging enhanced the resting activity of the mitochondrial ATP synthase, whereas in young cells, the enzyme operated mainly in reverse mode. Melatonin treatment prevented all these changes. Aging reduced both spontaneous and stimulated contraction of colonic strips and shifted the metabolic dependence of contraction from mitochondria to glycolysis, as indicated the use of mitochondrial and glycolysis inhibitors. These functional alterations were also palliated by melatonin treatment. Aging effects were not related to a decrease in Ca2+ store mobilization, because this was enhanced in aged cells and restored by melatonin. In conclusion, melatonin prevents the age induced in situ mitochondrial potential alterations in smooth muscle cells and the associated changes in contractility and metabolism.

Melatonin prevents pancreatic β-cell loss due to glucotoxicity: the relationship between oxidative stress and endoplasmic reticulum stress

Prolonged hyperglycemia results in pancreatic β-cell dysfunction and apoptosis, referred to as glucotoxicity. Although both oxidative and endoplasmic reticulum (ER) stresses have been implicated as major causative mechanisms of β-cell glucotoxicity, the reciprocal importance between the two remains to be elucidated. The aim of this study was to evaluate the differential effect of oxidative stress and ER stress on β-cell glucotoxicity, by employing melatonin which has free radical-scavenging and antioxidant properties. As expected, in β-cells exposed to prolonged high glucose levels, cell viability and glucose-stimulated insulin secretion (GSIS) were significantly impaired. Melatonin treatment markedly attenuated cellular apoptosis by scavenging reactive oxygen species via its plasmalemmal receptor-independent increase in antioxidant enzyme activity. However, treatments with antioxidants alone were insufficient to recover the impaired GSIS. Interestingly, 4-phenylbutyric acid (4-PBA), a chemical chaperone that attenuate ER stress by stabilizing protein structure, alleviated the impaired GSIS, but not apoptosis, suggesting that glucotoxicity induces oxidative and ER stress independently. We found that cotreatment of glucotoxic β-cells with melatonin and 4-PBA dramatically improved both their survival and insulin secretion. Taken together, these results suggest that ER stress may be the more critical mechanism for prolonged high-glucose-induced GSIS impairment, whereas oxidative stress appears to be more critical for the impaired β-cell viability. Therefore, combinatorial therapy of melatonin with an ER stress modifier may help recover pancreatic β-cells under glucotoxic conditions in type 2 diabetes.

Endothelium and its alterations in cardiovascular diseases: life style intervention

The endothelium, which forms the inner cellular lining of blood vessels and lymphatics, is a highly metabolically active organ that is involved in many physiopathological processes, including the control of vasomotor tone, barrier function, leukocyte adhesion, and trafficking and inflammation. In this review, we summarized and described the following: (i) endothelial cell function in physiological conditions and (ii) endothelial cell activation and dysfunction in the main cardiovascular diseases (such as atherosclerosis, and hypertension) and to diabetes, cigarette smoking, and aging physiological process. Finally, we presented the currently available evidence that supports the beneficial effects of physical activity and various dietary compounds on endothelial functions.

Linkages between mitochondrial lipids and life history in temperate and tropical birds

Temperate birds tend to have a fast pace of life and short life spans with high reproductive output, whereas tropical birds tend to have a slower pace of life, invest fewer resources in reproduction, and have higher adult survival rates. How these differences in life history at the organismal level are rooted in differences at the cellular level is a major focus of current research. Here, we cultured fibroblasts from phylogenetically paired tropical and temperate species, isolated mitochondria from each, and compared their mitochondrial membrane lipids. We also correlated the amounts of these lipids with an important life history parameter, clutch size. We found that tropical birds tended to have less mitochondrial lipid per cell, especially less cardiolipin per cell, suggesting that cells from tropical birds have fewer mitochondria or less inner mitochondrial membrane per cell. We also found that the mitochondria of tropical birds and the species with the smallest clutch sizes had higher amounts of plasmalogens, a lipid that could serve as an antioxidant. Overall, our findings are consistent with the idea that there are underlying molecular and cellular physiological traits that could account for the differences in whole-animal physiology between animals with different life histories.