Potential utility of melatonin as an antioxidant during pregnancy and in the perinatal period

Kidney Programming and Hypertension: Linking Prenatal Development to Adulthood

The complex relationship between kidney disease and hypertension represents a critical area of research, yet less attention has been devoted to exploring how this connection develops early in life. Various environmental factors during pregnancy and lactation can significantly impact kidney development, potentially leading to kidney programming that results in alterations in both structure and function. This early programming can contribute to adverse long-term kidney outcomes, such as hypertension. In the context of kidney programming, the molecular pathways involved in hypertension are intricate and include epigenetic modifications, oxidative stress, impaired nitric oxide pathway, inappropriate renin-angiotensin system (RAS) activation, disrupted nutrient sensing, gut microbiota dysbiosis, and altered sodium transport. This review examines each of these mechanisms and highlights reprogramming interventions proposed in preclinical studies to prevent hypertension related to kidney programming. Given that reprogramming strategies differ considerably from conventional treatments for hypertension in kidney disease, it is essential to shift focus toward understanding the processes of kidney programming and its role in the development of programmed hypertension.

Melatonin-mediated actions and circadian functions that improve implantation, fetal health and pregnancy outcome

This review summarizes data related to the potential importance of the ubiquitously functioning antioxidant, melatonin, in resisting oxidative stress and protecting against common pathophysiological disorders that accompany implantation, gestation and fetal development. Melatonin from the maternal pineal gland, but also trophoblasts in the placenta, perhaps in the mitochondria, produce this molecule as a hedge against impairment of the uteroplacental unit. We also discuss the role of circadian disruption on reproductive disorders of pregnancy. The common disorders of pregnancy, i.e., stillborn fetus, recurrent fetal loss, preeclampsia, fetal growth retardation, premature delivery, and fetal teratology are all conditions in which elevated oxidative stress plays a role and experimental supplementation with melatonin has been shown to reduce the frequency or severity of these conditions. Moreover, circadian disruption often occurs during pregnancy and has a negative impact on fetal health; conversely, melatonin has circadian rhythm synchronizing actions to overcome the consequences of chronodisruption which often appear postnatally. In view of the extensive findings supporting the ability of melatonin, an endogenously-produced and non-toxic molecule, to protect against experimental placental, fetal, and maternal pathologies, it should be given serious consideration as a supplement to forestall the disorders of pregnancy. Until recently, the collective idea was that melatonin supplements should be avoided during pregnancy. The data summarized herein suggests otherwise. The current findings coupled with the evidence, published elsewhere, showing that melatonin is highly protective of the fertilized oocyte from oxidative damage argues in favor of its use for improving pregnancy outcome generally.

Melatonin Use during Pregnancy and Lactation Complicated by Oxidative Stress: Focus on Offspring's Cardiovascular-Kidney-Metabolic Health in Animal Models

Cardiovascular-kidney-metabolic (CKM) syndrome has emerged as a major global public health concern, posing a substantial threat to human health. Early-life exposure to oxidative stress may heighten vulnerability to the developmental programming of adult diseases, encompassing various aspects of CKM syndrome. Conversely, the initiation of adverse programming processes can potentially be thwarted through early-life antioxidant interventions. Melatonin, originally recognized for its antioxidant properties, is an endogenous hormone with diverse biological functions. While melatonin has demonstrated benefits in addressing disorders linked to oxidative stress, there has been comparatively less focus on investigating its reprogramming effects on CKM syndrome. This review consolidates the current knowledge on the role of oxidative stress during pregnancy and lactation in inducing CKM traits in offspring, emphasizing the underlying mechanisms. The multifaceted role of melatonin in regulating oxidative stress, mediating fetal programming, and preventing adverse outcomes in offspring positions it as a promising reprogramming strategy. Currently, there is a lack of sufficient information in humans, and the available evidence primarily originates from animal studies. This opens up new avenues for novel preventive intervention in CKM syndrome.

Melatonin: the placental antioxidant and anti-inflammatory

Melatonin (N-acetyl-5-methoxytryptamine) is an indolamine hormone with many physiological and biological roles. Melatonin is an antioxidant, anti-inflammatory, free radical scavenger, circadian rhythm regulator, and sleep hormone. However, its most popular role is the ability to regulate sleep through the circadian rhythm. Interestingly, recent studies have shown that melatonin is an important and essential hormone during pregnancy, specifically in the placenta. This is primarily due to the placenta's ability to synthesize its own melatonin rather than depending on the pineal gland. During pregnancy, melatonin acts as an antioxidant and anti-inflammatory, which is necessary to ensure a stable environment for both the mother and the fetus. It is an essential antioxidant in the placenta because it reduces oxidative stress by constantly scavenging for free radicals, i.e., maintain the placenta's integrity. In a healthy pregnancy, the maternal immune system is constantly altered to accommodate the needs of the growing fetus, and melatonin acts as a key anti-inflammatory by regulating immune homeostasis during early and late gestation. This literature review aims to identify and summarize melatonin's role as a powerful antioxidant and anti-inflammatory that reduces oxidative stress and inflammation to maintain a favorable homeostatic environment in the placenta throughout gestation.

Melatonin-Attenuated Oxidative Stress in High-Risk Pregnant Women Receiving Enoxaparin and Aspirin

Objective

In pregnancy, reducing inflammation and oxidative stress is important. Administration of melatonin during pregnancy can improve reproductive performance by improving the placental antioxidant system and inflammatory response. This investigation was carried out to evaluate the beneficial impact of melatonin on the oxidative stress state among high-risk pregnant women receiving enoxaparin and aspirin.

Methods

In this double-blind, placebo-controlled trial, 40 pregnant women, aged 15-45 years at 6 weeks of pregnancy, were randomly selected and divided into intervention and control groups. The control group received prophylaxis enoxaparin and aspirin once daily between 6 and 16 weeks of pregnancy. The intervention group was taken enoxaparin and aspirin for 9 weeks and melatonin once daily from the sixth week of pregnancy to delivery time. Blood samples were taken to measure some oxidative stress biomarkers including total antioxidant capacity (TAC), malondialdehyde (MDA), total thiol (T-SH), protein carbonyl (PCO), and nitric oxide (NO). The level of high-sensitivity C-reactive protein (hs-CRP) was also determined.

Results

TAC and T-SH levels increased significantly in the intervention group in comparison with the control group. Melatonin administration compared to the control group led to a significantly decreased level of NO and an insignificant hs-CRP level.

Conclusion

Melatonin supplementation in high-risk pregnancy had favorable effects on TAC, T-SH, NO, and hs-CRP levels, improved antioxidant activity, and reduced inflammation. More studies are needed in different pregnancy conditions along with the measurement of different biomarkers.

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.

Perinatal Oxidative Stress and Kidney Health: Bridging the Gap between Animal Models and Clinical Reality

Oxidative stress arises when the generation of reactive oxygen species or reactive nitrogen species overwhelms antioxidant systems. Developing kidneys are vulnerable to oxidative stress, resulting in adult kidney disease. Oxidative stress in fetuses and neonates can be evaluated by assessing various biomarkers. Using animal models, our knowledge of oxidative-stress-related renal programming, the molecular mechanisms underlying renal programming, and preventive interventions to avert kidney disease has grown enormously. This comprehensive review provides an overview of the impact of perinatal oxidative stress on renal programming, the implications of antioxidant strategies on the prevention of kidney disease, and the gap between animal models and clinical reality.

The neonatal ketone body is important for primordial follicle pool formation and regulates ovarian ageing in mice

Adverse nutritional conditions during the perinatal stage are related to early menopause in adulthood; however, the underlying mechanism is still unclear. Herein, we revealed that colostrum-activated ketone body elevation during the postnatal stage regulated primordial follicle reservoir size and then affected ovarian ageing. We found that the expression of the ketogenesis rate-limiting enzyme 3-hydroxy-3-methylglutaryl-CoA synthase 2 (Hmgcs2) was largely enhanced during primordial follicle pool formation after birth and might be activated in the ovaries by colostrum. Reactive oxygen species (ROS) elevation in the ovaries leads to follicle apoptosis to deplete damaged follicles, while Hmgcs2 deficiency enhances follicle apoptosis and thus decreases the size of the primordial follicle pool and leads to premature ovarian ageing (POA), which might be related to the activation of cellular endogenous antioxidant system. All these defects could be rescued by ketone body administration, which suppressed ROS-activated follicle apoptosis. Our results suggest that the internal metabolic homeostasis of newborn mice is critical for the primordial reservoir and that any intrauterine and perinatal undernutrition could result in POA.

Is Melatonin the "Next Vitamin D"?: A Review of Emerging Science, Clinical Uses, Safety, and Dietary Supplements

Melatonin has become a popular dietary supplement, most known as a chronobiotic, and for establishing healthy sleep. Research over the last decade into cancer, Alzheimer's disease, multiple sclerosis, fertility, PCOS, and many other conditions, combined with the COVID-19 pandemic, has led to greater awareness of melatonin because of its ability to act as a potent antioxidant, immune-active agent, and mitochondrial regulator. There are distinct similarities between melatonin and vitamin D in the depth and breadth of their impact on health. Both act as hormones, affect multiple systems through their immune-modulating, anti-inflammatory functions, are found in the skin, and are responsive to sunlight and darkness. In fact, there may be similarities between the widespread concern about vitamin D deficiency as a "sunlight deficiency" and reduced melatonin secretion as a result of "darkness deficiency" from overexposure to artificial blue light. The trend toward greater use of melatonin supplements has resulted in concern about its safety, especially higher doses, long-term use, and application in certain populations (e.g., children). This review aims to evaluate the recent data on melatonin's mechanisms, its clinical uses beyond sleep, safety concerns, and a thorough summary of therapeutic considerations concerning dietary supplementation, including the different formats available (animal, synthetic, and phytomelatonin), dosing, timing, contraindications, and nutrient combinations.

Educational Review: The Impact of Perinatal Oxidative Stress on the Developing Kidney

Oxidative stress occurs when there is an imbalance between reactive oxygen species/reactive nitrogen species and antioxidant systems. The interplay between these complex processes is crucial for normal pregnancy and fetal development; however, when oxidative stress predominates, pregnancy related complications and adverse fetal programming such as preterm birth ensues. Understanding how oxidative stress negatively impacts outcomes for the maternal-fetal dyad has allowed for the exploration of antioxidant therapies to prevent and/or mitigate disease progression. In the developing kidney, the negative impact of oxidative stress has also been noted as it relates to the development of hypertension and kidney injury mostly in animal models. Clinical research addressing the implications of oxidative stress in the developing kidney is less developed than that of the neurodevelopmental and respiratory conditions of preterm infants and other vulnerable neonatal groups. Efforts to study the oxidative stress pathway along the continuum of the perinatal period using a team science approach can help to understand the multi-organ dysfunction that the maternal-fetal dyad sustains and guide the investigation of antioxidant therapies to ameliorate the global toxicity. This educational review will provide a comprehensive and multidisciplinary perspective on the impact of oxidative stress during the perinatal period in the development of maternal and fetal/neonatal complications, and implications on developmental programming of accelerated aging and cardiovascular and renal disease for a lifetime.

Effects of Melatonin Supplementation during Pregnancy on Reproductive Performance, Maternal-Placental-Fetal Redox Status, and Placental Mitochondrial Function in a Sow Model

Melatonin (MT) is a bio-antioxidant that has been widely used to prevent pregnancy complications, such as pre-eclampsia and IUGR during gestation. This experiment evaluated the impacts of dietary MT supplementation during pregnancy on reproductive performance, maternal-placental-fetal redox status, placental inflammatory response, and mitochondrial function, and sought a possible underlying mechanism in the placenta. Sixteen fifth parity sows were divided into two groups and fed each day of the gestation period either a control diet or a diet that was the same but for 36 mg of MT. The results showed that dietary supplementation with MT increased placental weight, while the percentage of piglets born with weight < 900 g decreased. Meanwhile, serum and placental MT levels, maternal-placental-fetal redox status, and placental inflammatory response were increased by MT. In addition, dietary MT markedly increased the mRNA levels of nutrient transporters and antioxidant-related genes involved in the Nrf2/ARE pathway in the placenta. Furthermore, dietary MT significantly increased ATP and NAD+ levels, relative mtDNA content, and the protein expression of Sirt1 in the placenta. These results suggested that MT supplementation during gestation could improve maternal-placental-fetal redox status and reproductive performance by ameliorating placental antioxidant status, inflammatory response, and mitochondrial dysfunction.

Melatonin augments the neuroprotective effects of hypothermia in lambs following perinatal asphyxia

Therapeutic hypothermia (TH) is standard care in high-resource birth settings for infants with neonatal encephalopathy. TH is partially effective and adjuvant therapies are needed. Here, we examined whether the antioxidant melatonin (MLT) provides additive benefit with TH, compared to TH alone or MLT alone, to improve recovery from acute encephalopathy in newborn lambs. Immediately before cesarean section delivery, we induced asphyxia in fetal sheep via umbilical cord occlusion until mean arterial blood pressure fell from 55 ± 3 mm Hg in sham controls to 18-20 mm Hg (10.1 ± 1.5 minutes). Lambs were delivered and randomized to control, control + MLT (60 mg iv, from 30 minutes to 24 hours), asphyxia, asphyxia + TH (whole-body cooling to 35.1 ± 0.8°C vs. 38.3 ± 0.17°C in sham controls, from 4-28 hours), asphyxia + MLT, and asphyxia + TH + MLT. At 72 hours, magnetic resonance spectroscopy (MRS) was undertaken, and then brains were collected for neuropathology assessment. Asphyxia induced abnormal brain metabolism on MRS with increased Lactate:NAA (P = .003) and reduced NAA:Choline (P = .005), induced apoptotic and necrotic cell death across gray and white matter brain regions (P < .05), and increased neuroinflammation and oxidative stress (P < .05). TH and MLT were independently associated with region-specific reductions in oxidative stress, inflammation, and cell death, compared to asphyxia alone. There was an interaction between TH and MLT such that the NAA:Choline ratio was not significantly different after asphyxia + TH + MLT compared to sham controls but had a greater overall reduction in neuropathology than either treatment alone. This study demonstrates that, in newborn lambs, combined TH + MLT for neonatal encephalopathy provides significantly greater neuroprotection than either alone. These results will guide the development of further trials for neonatal encephalopathy.

Clinical Application of Antioxidants to Improve Human Oocyte Mitochondrial Function: A Review

Mitochondria produce adenosine triphosphate (ATP) while also generating high amounts of reactive oxygen species (ROS) derived from oxygen metabolism. ROS are small but highly reactive molecules that can be detrimental if unregulated. While normally functioning mitochondria produce molecules that counteract ROS production, an imbalance between the amount of ROS produced in the mitochondria and the capacity of the cell to counteract them leads to oxidative stress and ultimately to mitochondrial dysfunction. This dysfunction impairs cellular functions through reduced ATP output and/or increased oxidative stress. Mitochondrial dysfunction may also lead to poor oocyte quality and embryo development, ultimately affecting pregnancy outcomes. Improving mitochondrial function through antioxidant supplementation may enhance reproductive performance. Recent studies suggest that antioxidants may treat infertility by restoring mitochondrial function and promoting mitochondrial biogenesis. However, further randomized, controlled trials are needed to determine their clinical efficacy. In this review, we discuss the use of resveratrol, coenzyme-Q10, melatonin, folic acid, and several vitamins as antioxidant treatments to improve human oocyte and embryo quality, focusing on the mitochondria as their main hypothetical target. However, this mechanism of action has not yet been demonstrated in the human oocyte, which highlights the need for further studies in this field.

Melatonin 1A and 1B Receptors' Expression Decreases in the Placenta of Women with Fetal Growth Restriction

Melatonin and its metabolites prevent oxidative stress and apoptosis, and it is actively produced by the placenta during pregnancy. Melatonin 1A and 1B receptors are present in human villous trophoblastic cells. We aimed to investigate the expression of melatonin 1A and 1B receptors in human placental tissue in the case of placental insufficiency manifested as the intrauterine growth restriction syndrome of the fetus (IUGR). Thirty-two pregnant women aged 18-36 with placental insufficiency manifested at the term 36 weeks of gestation as the IUGR syndrome (the estimated fetal weight less than the 3rd percentile) were included in the experimental group; all their babies had the diagnosis confirmed at birth, which occurred after 37 weeks of gestation. The control group consisted of 30 women with uncomplicated pregnancy of the same term. Pieces of the placental tissue were obtained after deliveries, and melatonin 1A and 1B receptors were immunoassayed; the richness of melatonin receptors in the placental tissue was estimated on the basis of immunohistochemical (IHC) staining of receptors, calculated in the IHC image score. The optical density of melatonin 1A receptors in the placentas obtained from women whose pregnancies were complicated with IUGR was significantly lower than that in the placentas from uncomplicated pregnancies: generally in the trophoblast, it was 0.095 ± 0.0009 IHC image score (in the control group, 0.194 ± 0.0015, p < 0.0001); in the apical parts of the syncytiotrophoblast, 0.108 ± 0.0016 IHC image score (in the control group, 0.221 ± 0.0013, p < 0.0001); and in the stromal cells of placental villi, 0.112 ± 0.0013 IHC image score (in the control group, 0.156 ± 0.0011, p < 0.0001). The optical density of melatonin 1B receptors in placentas obtained from women whose pregnancies were complicated with IUGR was also lower than that in the placentas from uncomplicated pregnancies: generally in the trophoblast, it was 0.165 ± 0.0019 IHC image score (in the control group, 0.231 ± 0.0013, p < 0.0001), and in the apical parts of the syncytiotrophoblast, 0.188 ± 0.0028 IHC image score (in the control group, 0.252 ± 0.0009, p < 0.0001). There was no difference found in the optical density of melatonin 1B receptors in the stromal cells of placental villi between the two groups: in the experimental group, 0.109 ± 0.006 IHC image score, and in the control group, 0.114 ± 0.0011 (p = 0.65). Melatonin receptors 1A and 1B are significantly less expressed in the placental tissue in the case that pregnancy is complicated with placental insufficiency, manifested as the intrauterine growth restriction syndrome of the fetus.

Melatonin long-lasting beneficial effects on pulmonary vascular reactivity and redox balance in chronic hypoxic ovine neonates

Pulmonary arterial hypertension of the neonate (PAHN) is a pathophysiological condition characterized by maladaptive pulmonary vascular remodeling and abnormal contractile reactivity. This is a multifactorial syndrome with chronic hypoxia and oxidative stress as main etiological drivers, and with limited effectiveness in therapeutic approaches. Melatonin is a neurohormone with antioxidant and vasodilator properties at the pulmonary level. Therefore, this study aims to test whether a postnatal treatment with melatonin during the neonatal period improves in a long-lasting manner the clinical condition of PAHN. Ten newborn lambs gestated and born at 3600 m were used in this study, five received vehicle and five received melatonin in daily doses of 1 mg kg^-1 for the first 3 weeks of life. After 1 week of treatment completion, lung tissue and small pulmonary arteries (SPA) were collected for wire myography, molecular biology, and morphostructural analyses. Melatonin decreased pulmonary arterial pressure the first 4 days of treatment. At 1 month old, melatonin decreased the contractile response to the vasoconstrictors K⁺ , TX₂ , and ET-1. Further, melatonin increased the endothelium-dependent and muscle-dependent vasodilation of SPA. Finally, the treatment decreased pulmonary oxidative stress by inducing antioxidant enzymes and diminishing pro-oxidant sources. In conclusion, melatonin improved vascular reactivity and oxidative stress at the pulmonary level in PAHN lambs gestated and born in chronic hypoxia.

Melatonin for prevention of placental malperfusion and fetal compromise associated with intrauterine inflammation-induced oxidative stress in a mouse model

Melatonin has been shown to reduce oxidative stress and mitigate hypercoagulability. We hypothesized that maternally administered melatonin may reduce placental oxidative stress and hypercoagulability associated with exposure to intrauterine inflammation (IUI) and consequently improve fetoplacental blood flow and fetal sequelae. Mice were randomized to the following groups: control (C), melatonin (M), lipopolysaccharide (LPS; a model of IUI) (L), and LPS with melatonin (ML). The expression of antioxidant mediators in the placenta was significantly decreased, while that of pro-inflammatory mediators was significantly increased in L compared to C and ML. The systolic/diastolic ratio, resistance index, and pulsatility index in uterine artery (UtA) and umbilical artery (UA) were significantly increased in L compared with other groups when analyzed by Doppler ultrasonography. The expression of antioxidant mediators in the placenta was significantly decreased, while that of pro-inflammatory mediators was significantly increased in L compared to C and ML. Vascular endothelial damage and thrombi formation, as evidenced by fibrin deposits, were similarly increased in L compared to other groups. Maternal pretreatment with melatonin appears to modulate maternal placental malperfusion, fetal cardiovascular compromise, and fetal neuroinflammation induced by IUI through its antioxidant properties.

The usefulness of melatonin in the field of obstetrics and gynecology

Disorders of the female reproductive system, including those associated with hormone regulation, fertility rate and fetal health, are issues of great concern worldwide. More recently, melatonin supplementation has been suggested as a therapeutic approach in gynecological practice. In both animal models and in women, melatonin supplementation suggests a therapeutic and preventative potential, effects attributed mainly to its antioxidant properties and action as hormone modulator. The aim of this literature review is to further investigate the evidence available on the effects of melatonin supplementation in animal and human studies, focusing on its potential application to gynecology. Melatonin-containing supplements are easily found in online and high street retailers, and despite its supplementation deemed to be relatively safe, no consensus has been reached on effective dosage and supplementation period. Short term supplementation studies, of up to six months, suggest that a daily posology of 2-18 mg of melatonin may have the potential to improve fertility rate, oocyte quality, maturation and number of embryos. However, the evidence available so far on the effects of melatonin supplementation covering gestational age and gestational outcomes is very scarce. Clinical trials and longer-term supplementation studies are required to assess any clinical outcome associated with melatonin supplementation in the field of gynecology.

Melatonin protects spermatogonia from the stress of chemotherapy and oxidation via eliminating reactive oxidative species

Busulfan is a widely used chemotherapeutic drug for chronic myelogenous leukemia and bone marrow transplantation. As a cell cycle nonspecific alkylation agent, busulfan has a severe side effect on germ cells, especially on spermatogonia before meiosis. Studies have revealed that busulfan causes DNA strand crosslinks in spermatogonia and induces apoptosis, and many corresponding strategies have been developed to ameliorate the side effects. However, fertility maintenance after busulfan treatment is still a challenging project in the clinic. Here, we demonstrated that continuous injection of melatonin effectively alleviated germline cytotoxicity both in recipient mice and cultured spermatogonia, and busulfan/melatonin recipient mice produced normal litters. We further revealed that melatonin rescues spermatogonia from apoptosis by neutralizing reactive oxidative species (ROS) induced by busulfan and recovered the phosphorylation of ATM and p53 to normal levels, and as a result apoptosis in spermatogonial progenitor cells was avoided. This study reports that pineal gland hormone melatonin effectively protects spermatogonia from the stress of chemotherapy and oxidation and reveals the underlying molecular mechanisms, which will provide an important hint for fertility protection in clinic.

Melatonin as a master regulator of cell death and inflammation: molecular mechanisms and clinical implications for newborn care

Melatonin, more commonly known as the sleep hormone, is mainly secreted by the pineal gland in dark conditions and regulates the circadian rhythm of the organism. Its intrinsic properties, including high cell permeability, the ability to easily cross both the blood–brain and placenta barriers, and its role as an endogenous reservoir of free radical scavengers (with indirect extra activities), confer it beneficial uses as an adjuvant in the biomedical field. Melatonin can exert its effects by acting through specific cellular receptors on the plasma membrane, similar to other hormones, or through receptor-independent mechanisms that involve complex molecular cross talk with other players. There is increasing evidence regarding the extraordinary beneficial effects of melatonin, also via exogenous administration. Here, we summarize molecular pathways in which melatonin is considered a master regulator, with attention to cell death and inflammation mechanisms from basic, translational and clinical points of view in the context of newborn care.

Antenatal melatonin modulates an enhanced antioxidant/pro-oxidant ratio in pulmonary hypertensive newborn sheep

Chronic hypobaric hypoxia during fetal and neonatal life induces neonatal pulmonary hypertension. Hypoxia and oxidative stress are driving this condition, which implies an increase generation of reactive oxygen species (ROS) and/or decreased antioxidant capacity. Melatonin has antioxidant properties that decrease oxidative stress and improves pulmonary vascular function when administered postnatally. However, the effects of an antenatal treatment with melatonin in the neonatal pulmonary function and oxidative status are unknown. Therefore, we hypothesized that an antenatal therapy with melatonin improves the pulmonary arterial pressure and antioxidant status in high altitude pulmonary hypertensive neonates. Twelve ewes were bred at high altitude (3600 m); 6 of them were used as a control group (vehicle 1.4% ethanol) and 6 as a melatonin treated group (10 mg d-1 melatonin in vehicle). Treatments were given once daily during the last third of gestation (100-150 days). Lambs were born and raised with their mothers until 12 days old, and neonatal pulmonary arterial pressure and resistance, plasma antioxidant capacity and the lung oxidative status were determined. Furthermore, we measured the pulmonary expression and activity for the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase, and the oxidative stress markers 8-isoprostanes, 4HNE and nitrotyrosine. Finally, we assessed pulmonary pro-oxidant sources by the expression and function of NADPH oxidase, mitochondria and xanthine oxidase. Melatonin decreased the birth weight. However, melatonin enhanced the plasma antioxidant capacity and decreased the pulmonary antioxidant activity, associated with a diminished oxidative stress during postnatal life. Interestingly, melatonin also decreased ROS generation at the main pro-oxidant sources. Our findings suggest that antenatal administration of melatonin programs an enhanced antioxidant/pro-oxidant status, modulating ROS sources in the postnatal lung.

Melatonin treatment in fetal and neonatal diseases

This literature review aims to address the main scientific findings on oxidative stress activity in different gestational disorders, as well as the function and application of melatonin in the treatment of fetal and neonatal changes. Oxidative stress has been associated with the etiopathogenesis of recurrent miscarriages, preeclampsia, intrauterine growth restriction, and stillbirth. Both, the exacerbated consumption of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase, and the increased synthesis of reactive oxygen species, such as superoxide, peroxynitrite, and hydrogen peroxide, induce phospholipid peroxidation and endothelial dysfunction, impaired invasion and death of trophoblast cells, impaired decidualization, and remodeling of maternal spiral arteries. It has been postulated that melatonin induces specific biochemical responses that regulate cell proliferation in fetuses, and that its antioxidant action promotes bioavailability of nitric oxide and, thus, placental perfusion and also fetal nutrition and oxygenation. Therefore, the therapeutic action of melatonin has been the subject of major studies that aim to minimize or prevent different injuries affecting this pediatric age group, such as intrauterine growth restriction, encephalopathy, chronic lung diseases, retinopathy of prematurity Conclusion: the results antioxidant and indicate that melatonin is an important therapy for the clinical treatment of these diseases.

PRO-OXIDANTS AND ANTIOXIDANTS IN RETINOPATHY OF PREMATURITY

- Premature infants are susceptible to oxidative stress that causes neonatal disease such as retinopathy of prematurity (ROP). Oxidative stress is an imbalance between the production of pro-oxidants and the ability of the body to detoxify their harmful effects by antioxidants. The proliferative phase 2 ROP occurs at around 33^rd postmenstrual week (pmw). The purpose of our study was to evaluate the pro-oxidant/antioxidant status in preterm infants at 33^rd pmw. The study included 59 premature infants. ROP was classified according to the International Classification of Retinopathy of Prematurity. Total oxidative status (TOS), total antioxidant status (TAS), malondialdehyde (MDA) and paraoxonase 1 (PON1) activity were determined spectrophotometrically. The values of the pro-oxidants TOS and MDA were significantly higher in infants with ROP as compared to infants without ROP (p<0.05 both). There were no significant differences in the values of TAS and PON1 between the infants with and without ROP. According to study results, TOS and MDA are good markers of oxidative stress, whereas TAS and PON1 activity are unreliable in assessing antioxidant protection.

The effect of oxidative stress induced by tert-butylhydroperoxide under distinct folic acid conditions: An in vitro study using cultured human trophoblast-derived cells

Preeclampsia is a pregnancy disorder characterized by high maternal blood pressure, fetal growth restriction and intrauterine hypoxia. Folic acid is a vitamin required during pregnancy. In this work, we investigated the relationship between preeclampsia and the intake of distinct doses of folic acid during pregnancy. Considering that preeclampsia is associated with increased placental oxidative stress levels, we investigated the effect of oxidative stress induced by tert-butylhydroperoxide (TBH) in human trophoblast-derived cells cultured upon deficient/low, physiological and supra-physiological folic acid levels. The negative effect of TBH upon thiobarbituric acid reactive substances (TBARS), total, reduced and oxidized glutathione, cell viability, cell proliferation, culture growth and cell migration was more marked under folic acid excess. This study suggests more attention on the dose administered, and ultimately, on the overall folic acid levels during pregnancy, in the context of preeclampsia risk.

Melatonin and health: an umbrella review of health outcomes and biological mechanisms of action

BACKGROUND

Our aims were to evaluate critically the evidence from systematic reviews as well as narrative reviews of the effects of melatonin (MLT) on health and to identify the potential mechanisms of action involved.

METHODS

An umbrella review of the evidence across systematic reviews and narrative reviews of endogenous and exogenous (supplementation) MLT was undertaken. The Oxman checklist for assessing the methodological quality of the included systematic reviews was utilised. The following databases were searched: MEDLINE, EMBASE, Web of Science, CENTRAL, PsycINFO and CINAHL. In addition, reference lists were screened. We included reviews of the effects of MLT on any type of health-related outcome measure.

RESULTS

Altogether, 195 reviews met the inclusion criteria. Most were of low methodological quality (mean -4.5, standard deviation 6.7). Of those, 164 did not pool the data and were synthesised narratively (qualitatively) whereas the remaining 31 used meta-analytic techniques and were synthesised quantitatively. Seven meta-analyses were significant with P values less than 0.001 under the random-effects model. These pertained to sleep latency, pre-operative anxiety, prevention of agitation and risk of breast cancer.

CONCLUSIONS

There is an abundance of reviews evaluating the effects of exogenous and endogenous MLT on health. In general, MLT has been shown to be associated with a wide variety of health outcomes in clinically and methodologically heterogeneous populations. Many reviews stressed the need for more high-quality randomised clinical trials to reduce the existing uncertainties.

Melatonin as a Therapeutic Resource for Inflammatory Visual Diseases

BACKGROUND

Uveitis and optic neuritis are prevalent ocular inflammatory diseases, and highly damaging ocular conditions. Both diseases are currently treated with corticosteroids, but they do not have adequate efficacy and are often associated with severe side effects. Thus, uveitis and optic neuritis remain a challenging field to ophthalmologists and a significant public health concern.

OBJECTIVE

This review summarizes findings showing the benefits of a treatment with melatonin in experimental models of these inflammatory ocular diseases.

RESULTS

Oxidative and nitrosative damage, tumor necrosis factor, and prostaglandin production have been involved in the pathogeny of uveitis and optic neuritis. Melatonin is an efficient antioxidant and antinitridergic, and has the ability to reduce prostaglandin and tumor necrosis factor levels both in the retina and optic nerve. Moreover, melatonin not only prevents functional and structural consequences of experimental uveitis and optic neuritis, but it is also capable of suppressing the actively ongoing ocular inflammatory response.

CONCLUSIONS

Since melatonin protects ocular tissues against inflammation, it could be a potentially useful anti-inflammatory therapy in ophthalmology.

Melatonin and the newborn brain

Brain injury related to preterm birth and neonatal asphyxia is a leading cause of childhood neuromotor and cognitive disabilities. Unfortunately, the strategies to prevent perinatal brain damages remain limited. Among the candidate molecules, melatonin appears to be one of the most promising agents for its antioxidant and neuromodulatory action. Robust preclinical evidences and few clinical studies have suggested a neuroprotective benefit conferred by neonatal exposure to melatonin. This review recapitulates current basic research, safety and pharmacokinetic data and ongoing clinical trials on the use of melatonin as a neuroprotective agent in the newborn.

Oxidative Profile and δ-Aminolevulinate Dehydratase Activity in Healthy Pregnant Women with Iron Supplementation

An oxidative burst occurs during pregnancy due to the large consumption of oxygen in the tissues and an increase in metabolic demands in response to maternal physiological changes and fetal growth. This study aimed to determine the oxidative profile and activity of δ-aminolevulinate dehydratase (δ-ALA-D) in pregnant women who received iron supplementation. Oxidative stress parameters were evaluated in 25 pregnant women with iron supplementation, 25 pregnant women without supplementation and 25 non-pregnant women. The following oxidative stress parameters were evaluated: thiobarbituric acid reactive substances (TBARS), protein thiol groups (P-SH), non-protein thiol levels (NP-SH), vitamin C levels, catalase and δ-ALA-D activity. Markers of oxidative stress and cell damage, such as TBARS in plasma were significantly higher in pregnant women without supplementation. Levels of P-SH, NP-SH and δ-ALA-D activity were significantly lower in pregnant women without supplementation compared to non-pregnant and pregnant women with supplementation, while vitamin C levels were significantly lower in pregnant women without supplementation when compared to non-pregnant women. The increase in the generation of oxidative species and decrease of antioxidants suggest the loss of physiological oxidative balance during normal pregnancy, which was not observed in pregnant women with iron supplementation, suggesting a protective effect of iron against oxidative damage.

Melatonin for women in pregnancy for neuroprotection of the fetus

BACKGROUND

Melatonin is an antioxidant with anti-inflammatory and anti-apoptotic effects. Animal studies have supported a fetal neuroprotective role for melatonin when administered maternally. It is important to assess whether melatonin, given to the mother, can reduce the risk of neurosensory disabilities (including cerebral palsy) and death, associated with fetal brain injury, for the preterm or term compromised fetus.

OBJECTIVES

To assess the effects of melatonin when used for neuroprotection of the fetus.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2016).

SELECTION CRITERIA

We planned to include randomised controlled trials and quasi-randomised controlled trials comparing melatonin given to women in pregnancy (regardless of the route, timing, dose and duration of administration) for fetal neuroprotection with placebo, no treatment, or with an alternative agent aimed at providing fetal neuroprotection. We also planned to include comparisons of different regimens for administration of melatonin.

DATA COLLECTION AND ANALYSIS

Two review authors planned to independently assess trial eligibility, trial quality and extract the data.

MAIN RESULTS

We found no randomised trials for inclusion in this review. One study is ongoing.

AUTHORS' CONCLUSIONS

As we did not identify any randomised trials for inclusion in this review, we are unable to comment on implications for practice at this stage.Although evidence from animals studies has supported a fetal neuroprotective role for melatonin when administered to the mother during pregnancy, no trials assessing melatonin for fetal neuroprotection in pregnant women have been completed to date. However, there is currently one ongoing randomised controlled trial (with an estimated enrolment target of 60 pregnant women) which examines the dose of melatonin, administered to women at risk of imminent very preterm birth (less than 28 weeks' gestation) required to reduce brain damage in the white matter of the babies that were born very preterm.Further high-quality research is needed and research efforts should directed towards trials comparing melatonin with either no intervention (no treatment or placebo), or with alternative agents aimed at providing fetal neuroprotection (such as magnesium sulphate for the very preterm infant). Such trials should evaluate maternal and infant short- and longer-term outcomes (including neurosensory disabilities such as cerebral palsy), and consider the costs of care.

Salivary melatonin levels and sleep-wake rhythms in pregnant women with hypertensive and glucose metabolic disorders: A prospective analysis

In preeclampsia and gestational diabetes, the sympathetic nerves are activated, leading to disrupted sleep. Melatonin, which transmits information to regulate the sleep-wake rhythm and other such biorhythms, has been implicated in insulin resistance, antioxidant behaviors, and metabolic syndrome. In addition, its reduced secretion increases the risk of hypertension and diabetes. The aim of this study was to elucidate the features of melatonin secretion, sleep quality, and sleep-wake rhythms in pregnant women with complications. Fifty-eight pregnant women with pregnancy complications (hypertensive or glucose metabolic disorders) and 40 healthy pregnant women completed questionnaires, including sleep logs and the Pittsburgh Sleep Quality Index (PSQI), during the second to third trimesters. Their salivary melatonin levels were also measured. Pregnant women with complications had significantly lower morning (p < 0.001), daytime (p < 0.01), evening (p < 0.001), night (p < 0.01), daily mean (p < 0.001), peak (p < 0.001), and bottom (p < 0.01) melatonin values than healthy pregnant women. Pregnant women with complications also had significantly smaller melatonin amplitudes than healthy pregnant women (p < 0.001). Among pregnant women with complications, the duration (p < 0.05) and frequency (p < 0.01) of wake after sleep-onset were significantly greater in the poor sleep group than in the favorable sleep group which was divided by PSQI cutoff value. Pregnant women with hypertensive or glucose metabolic disorder complications had smaller circadian variation in salivary melatonin secretion, and their values were lower throughout the day than healthy pregnant women.

Potential Utility of Melatonin in Preeclampsia, Intrauterine Fetal Growth Retardation, and Perinatal Asphyxia

AIM

Reactive oxygen species play an important role in the pathogenesis of several diseases during gestation and the perinatal period. During pregnancy, increased oxygen demand augments the rate of production of free radicals. Oxidative stress is involved in pregnancy disorders including preeclampsia and intrauterine fetal growth retardation (IUGR). Moreover, increased levels of oxidative stress and reduced antioxidative capacities may contribute to the pathogenesis of perinatal asphyxia. Melatonin, an efficient antioxidant agent, diffuses through biological membranes easily and exerts pleiotropic actions on every cell and appears to be essential for successful gestation. This narrative review summarizes current knowledge concerning the role of melatonin in reducing complications during human pregnancy and in the perinatal period.

RESULTS

Melatonin levels are altered in women with abnormally functioning placentae during preeclampsia and IUGR. Short-term melatonin therapy is highly effective and safe in reducing complications during pregnancy and in the perinatal period. Because melatonin has been shown to be safe for both mother and fetus, it could be an attractive therapy in pregnancy and is considered a promising neuroprotective agent in perinatal asphyxia.

CONCLUSION

We believe that the use of melatonin treatment during the late fetal and early neonatal period might result in a wide range of health benefits, improved quality of life, and may help limit complications during the critical periods prior to, and shortly after, delivery.

Melatonin: an ancient molecule that makes oxygen metabolically tolerable

Melatonin is remarkably functionally diverse with actions as a free radical scavenger and antioxidant, circadian rhythm regulator, anti-inflammatory and immunoregulating molecule, and as an oncostatic agent. We hypothesize that the initial and primary function of melatonin in photosynthetic cyanobacteria, which appeared on Earth 3.5-3.2 billion years ago, was as an antioxidant. The evolution of melatonin as an antioxidant by this organism was necessary as photosynthesis is associated with the generation of toxic-free radicals. The other secondary functions of melatonin came about much later in evolution. We also surmise that mitochondria and chloroplasts may be primary sites of melatonin synthesis in all eukaryotic cells that possess these organelles. This prediction is made on the basis that mitochondria and chloroplasts of eukaryotes developed from purple nonsulfur bacteria (which also produce melatonin) and cyanobacteria when they were engulfed by early eukaryotes. Thus, we speculate that the melatonin-synthesizing actions of the engulfed bacteria were retained when these organelles became mitochondria and chloroplasts, respectively. That mitochondria are likely sites of melatonin formation is supported by the observation that this organelle contains high levels of melatonin that are not impacted by blood melatonin concentrations. Melatonin has a remarkable array of means by which it thwarts oxidative damage. It, as well as its metabolites, is differentially effective in scavenging a variety of reactive oxygen and reactive nitrogen species. Moreover, melatonin and its metabolites modulate a large number of antioxidative and pro-oxidative enzymes, leading to a reduction in oxidative damage. The actions of melatonin on radical metabolizing/producing enzymes may be mediated by the Keap1-Nrf2-ARE pathway. Beyond its direct free radical scavenging and indirect antioxidant effects, melatonin has a variety of physiological and metabolic advantages that may enhance its ability to limit oxidative stress.

Melatonin reduces oxidative stress and improves vascular function in pulmonary hypertensive newborn sheep

Pulmonary hypertension of the newborn (PHN) constitutes a critical condition with severe cardiovascular and neurological consequences. One of its main causes is hypoxia during gestation, and thus, it is a public health concern in populations living above 2500 m. Although some mechanisms are recognized, the pathophysiological facts that lead to PHN are not fully understood, which explains the lack of an effective treatment. Oxidative stress is one of the proposed mechanisms inducing pulmonary vascular dysfunction and PHN. Therefore, we assessed whether melatonin, a potent antioxidant, improves pulmonary vascular function. Twelve newborn sheep were gestated, born, and raised at 3600 meters. At 3 days old, lambs were catheterized and daily cardiovascular measurements were recorded. Lambs were divided into two groups, one received daily vehicle as control and another received daily melatonin (1 mg/kg/d), for 8 days. At 11 days old, lung tissue and small pulmonary arteries (SPA) were collected. Melatonin decreased pulmonary pressure and resistance for the first 3 days of treatment. Further, melatonin significantly improved the vasodilator function of SPA, enhancing the endothelial- and muscular-dependent pathways. This was associated with an enhanced nitric oxide-dependent and nitric oxide independent vasodilator components and with increased nitric oxide bioavailability in lung tissue. Further, melatonin reduced the pulmonary oxidative stress markers and increased enzymatic and nonenzymatic antioxidant capacity. Finally, these effects were associated with an increase of lumen diameter and a mild decrease in the wall of the pulmonary arteries. These outcomes support the use of melatonin as an adjuvant in the treatment for PHN.

Oxidative stress-mediated aging during the fetal and perinatal periods

Oxidative stress is worldwide recognized as a fundamental component of the aging, a process that begins before birth. There is a critical balance between free radical generation and antioxidant defenses. Oxidative stress is caused by an imbalance between the production of free radicals and the ability of antioxidant system to detoxify them. Oxidative stress can occur early in pregnancy and continue in the postnatal period; this damage is implicated in the pathophysiology of pregnancy-related disorders, including recurrent pregnancy loss, preeclampsia and preterm premature rupture of membranes. Moreover, diseases of the neonatal period such as bronchopulmonary dysplasia, retinopathy of prematurity, necrotizing enterocolitis, and periventricular leukomalacia are related to free radical damage. The specific contribution of oxidative stress to the pathogenesis and progression of these neonatal diseases is only partially understood. This review summarizes what is known about the role of oxidative stress in pregnancy and in the pathogenesis of common disorders of the newborn, as a component of the early aging process.

Melatonin prevents maternal fructose intake-induced programmed hypertension in the offspring: roles of nitric oxide and arachidonic acid metabolites

Fructose intake has increased globally and is linked to hypertension. Melatonin was reported to prevent hypertension development. In this study, we examined whether maternal high fructose (HF) intake causes programmed hypertension and whether melatonin therapy confers protection against the process, with a focus on the link to epigenetic changes in the kidney using next-generation RNA sequencing (NGS) technology. Pregnant Sprague-Dawley rats received regular chow or chow supplemented with HF (60% diet by weight) alone or with additional 0.01% melatonin in drinking water during the whole period of pregnancy and lactation. Male offspring were assigned to four groups: control, HF, control + melatonin (M), and HF + M. Maternal HF caused increases in blood pressure (BP) in the 12-wk-old offspring. Melatonin therapy blunted the HF-induced programmed hypertension and increased nitric oxide (NO) level in the kidney. The identified differential expressed gene (DEGs) that are related to regulation of BP included Ephx2, Col1a2, Gucy1a3, Npr3, Aqp2, Hba-a2, and Ptgs1. Of which, melatonin therapy inhibited expression and activity of soluble epoxide hydrolase (SEH, Ephx2 gene encoding protein). In addition, we found genes in arachidonic acid metabolism were potentially involved in the HF-induced programmed hypertension and were affected by melatonin therapy. Together, our data suggest that the beneficial effects of melatonin are attributed to its ability to increase NO level in the kidney, epigenetic regulation of genes related to BP control, and inhibition of SEH expression. The roles of DEGs by the NGS in long-term epigenetic changes in the adult offspring kidney require further clarification.

Is melatonin ready to be used in preterm infants as a neuroprotectant?

The prevention of neurological disabilities following preterm birth remains a major public health challenge and efforts are still needed to test the neuroprotective properties of candidate molecules. Melatonin serves as a neuroprotectant in adult models of cerebral ischemia through its potent antioxidant and anti-inflammatory effects. An increasing number of preclinical studies have consistently demonstrated that melatonin protects the damaged developing brain by preventing abnormal myelination and an inflammatory glial reaction, a major cause of white matter injury. The main questions asked in this review are whether preclinical data on the neuroprotective properties of melatonin are sufficient to translate this concept into the clinical setting, and whether melatonin can reduce white matter damage in preterm infants. This review provides support for our view that melatonin is now ready to be tested in human preterm neonates, and discusses ongoing and planned clinical trials.

Melatonin improves cerebrovascular function and decreases oxidative stress in chronically hypoxic lambs

Chronic hypoxia during gestation and delivery results in oxidative stress and cerebrovascular dysfunction in the neonate. We assessed whether melatonin, a potent antioxidant and potential vasodilator, improves the cerebral vascular function in chronically hypoxic neonatal lambs gestated and born in the highlands (3600 m). Six lambs received melatonin (1 mg/kg per day oral) and six received vehicle, once a day for 8 days. During treatment, biometry and hemodynamic variables were recorded. After treatment, lambs were submitted to a graded FiO2 protocol to assess cardiovascular responses to oxygenation changes. At 12 days old, middle cerebral arteries (MCA) were collected for vascular reactivity, morphostructural, and immunostaining evaluation. Melatonin increased fractional growth at the beginning and improved carotid blood flow at all arterial PO2 levels by the end of the treatment (P < 0.05). Further, melatonin treatment improved vascular responses to potassium, serotonin, methacholine, and melatonin itself (P < 0.05). In addition, melatonin enhanced the endothelial response via nitric oxide-independent mechanisms in isolated arteries (162 ± 26 versus 266 ± 34 AUC, P < 0.05). Finally, nitrotyrosine staining as an oxidative stress marker decreased in the MCA media layer of melatonin-treated animals (0.01357 ± 0.00089 versus 0.00837 ± 0.00164 pixels/μm2 , P < 0.05). All the melatonin-induced changes were associated with no systemic cardiovascular alterations in vivo. In conclusion, oral treatment with melatonin modulates cerebral vascular function, resulting in a better cerebral perfusion and reduced oxidative stress in the neonatal period in chronically hypoxic lambs. Melatonin is a potential therapeutic agent for treating cerebrovascular dysfunction associated with oxidative stress and developmental hypoxia in neonates.

Melatonin as potential inducer of Th17 cell differentiation

The subset of T lymphocytes producing IL-17 (Th17) plays a key role in the immune system. It has been implicated in host defense, inflammatory diseases, tumorigenesis, autoimmune diseases, and transplant rejection. Careful analysis of the data available holds that Th17 cell subpopulation should be under the direct control of pineal hormone melatonin: the key Th17 differentiation factor RORα serves in the meantime as a high-affinity melatonin receptor. Since the levels of melatonin have diurnal and seasonal variation, as well as substantial deviations in some physiological or pathological conditions, melatonin-dependent regulation of Th17 cells should implicate multiform manifestation, such as influencing the outcome of infectious challenge or determining predisposition, etiology and progression of immune-related morbidities. Another important reason to raise a point of the new melatonin effects is current considering the possibilities of its clinical trials. Especially, the differentiation of Th17 upon melatonin treatment must aggravate the current recession in autoimmune diseases or induce serious complications in pregnancy.

Melatonin ameliorates brain injury induced by systemic lipopolysaccharide in neonatal rats

Our previous study showed that lipopolysaccharide (LPS)-induced brain injury in the neonatal rat is associated with nitrosative and oxidative stress. The present study was conducted to examine whether melatonin, an endogenous molecule with antioxidant properties, reduces systemic LPS-induced nitrosative and oxidative damage in the neonatal rat brain. Intraperitoneal (i.p.) injection of LPS (2mg/kg) was administered to Sprague-Dawley rat pups on postnatal day 5 (P5), and i.p. administration of melatonin (20mg/kg) or vehicle was performed 5min after LPS injection. Sensorimotor behavioral tests were performed 24h after LPS exposure, and brain injury was examined after these tests. The results show that systemic LPS exposure resulted in impaired sensorimotor behavioral performance, and acute brain injury, as indicated by the loss of oligodendrocyte immunoreactivity and a decrease in mitochondrial activity in the neonatal rat brain. Melatonin treatment significantly reduced LPS-induced neurobehavioral disturbances and brain damage in neonatal rats. The neuroprotective effect of melatonin was associated with attenuation of LPS-induced nitrosative and oxidative stress, as indicated by the decreased nitrotyrosine- and 4-hydroxynonenal-positive staining in the brain following melatonin and LPS exposure in neonatal rats. Further, melatonin significantly attenuated LPS-induced increases in the number of activated microglia in the neonatal rat brain. The protection provided by melatonin was also associated with a reduced number of inducible nitric oxide synthase (iNOS)+ cells, which were double-labeled with ED1 (microglia). Our results show that melatonin prevents the brain injury and neurobehavioral disturbances induced by systemic LPS exposure in neonatal rats, and its neuroprotective effects are associated with its impact on nitrosative and oxidative stress.

Melatonin: the watchdog of villous trophoblast homeostasis against hypoxia/reoxygenation-induced oxidative stress and apoptosis

Human placenta produces melatonin and expresses its receptors. We propose that melatonin, an antioxidant, protects the human placenta against hypoxia/reoxygenation (H/R)-induced damage. Primary term villous cytotrophoblasts were cultured under normoxia (8% O2) with or without 1mM melatonin for 72h to induce differentiation into the syncytiotrophoblast. The cells were then cultured for an additional 22h under normoxia or subjected to hypoxia (0.5% O2) for 4h followed by 18h reoxygenation (8% O2) with or without melatonin. H/R induced oxidative stress, which activated the Bax/Bcl-2 mitochondrial apoptosis pathway and the downstream fragmentation of DNA. Villous trophoblast treatment with melatonin reversed all the negative effects induced by H/R to normoxic levels. This study shows that melatonin protects the villous trophoblast against H/R-induced oxidative stress and apoptosis and suggests a potential preventive and therapeutic use of this indolamine in pregnancy complications characterized by syncytiotrophoblast survival alteration.

Melatonin potentiates the anticonvulsant action of phenobarbital in neonatal rats

Phenobarbital is the most commonly utilized drug for neonatal seizures. However, questions regarding safety and efficacy of this drug make it particularly compelling to identify adjunct therapies that could boost therapeutic benefit. One potential adjunct therapy is melatonin. Melatonin is used clinically in neonatal and pediatric populations, and moreover, it exerts anticonvulsant actions in adult rats. However, it has not been previously evaluated for anticonvulsant effects in neonatal rats. Here, we tested the hypothesis that melatonin would exert anticonvulsant effects, either alone, or in combination with phenobarbital. Postnatal day (P)7 rats were treated with phenobarbital (0-40mg/kg) and/or melatonin (0-80mg/kg) prior to chemoconvulsant challenge with pentylenetetrazole (100mg/kg). We found that melatonin significantly potentiated the anticonvulsant efficacy of phenobarbital, but did not exert anticonvulsant effects on its own. These data provide additional evidence for the further examination of melatonin as an adjunct therapy in neonatal/pediatric epilepsy.

Perinatal taurine exposure affects adult oxidative stress

Perinatal exposure to taurine (a β-amino acid) can alter adult physiological functions, including arterial pressure, hormonal and renal functions. Whereas perinatal taurine supplementation appears to have only minor effects on adult physiology, perinatal taurine depletion is associated with multiple adverse health effects, especially in animals postnatally exposed to other insults. New studies indicate that the mechanism for many of the physiological effects of taurine is related to the antioxidant activity of taurine. Thus the perinatal taurine depletion leads to oxidative stress in adult animals. It is likely that perinatal taurine depletion increases oxidative stress throughout life and that the early life taurine depletion leads to perinatal, epigenetic programming that impacts adult physiological function.

Peripheral reproductive organ health and melatonin: ready for prime time

Melatonin has a wide variety of beneficial actions at the level of the gonads and their adnexa. Some actions are mediated via its classic membrane melatonin receptors while others seem to be receptor-independent. This review summarizes many of the published reports which confirm that melatonin, which is produced in the ovary, aids in advancing follicular maturation and preserving the integrity of the ovum prior to and at the time of ovulation. Likewise, when ova are collected for in vitro fertilization-embryo transfer, treating them with melatonin improves implantation and pregnancy rates. Melatonin synthesis as well as its receptors have also been identified in the placenta. In this organ, melatonin seems to be of particular importance for the maintenance of the optimal turnover of cells in the villous trophoblast via its ability to regulate apoptosis. For male gametes, melatonin has also proven useful in protecting them from oxidative damage and preserving their viability. Incubation of ejaculated animal sperm improves their motility and prolongs their viability. For human sperm as well, melatonin is also a valuable agent for protecting them from free radical damage. In general, the direct actions of melatonin on the gonads and adnexa of mammals indicate it is an important agent for maintaining optimal reproductive physiology.

Roles of melatonin in fetal programming in compromised pregnancies

Compromised pregnancies such as those associated with gestational diabetes mellitus, intrauterine growth retardation, preeclampsia, maternal undernutrition, and maternal stress may negatively affect fetal development. Such pregnancies may induce oxidative stress to the fetus and alter fetal development through the epigenetic process that may affect development at a later stage. Melatonin is an oxidant scavenger that reverses oxidative stress during the prenatal period. Moreover, the role of melatonin in epigenetic modifications in the field of developmental programming has been studied extensively. Here, we describe the physiological function of melatonin in pregnancy and discuss the roles of melatonin in fetal programming in compromised pregnancies, focusing on its involvement in redox and epigenetic mechanisms.

Therapeutic applications of melatonin

Melatonin is a methoxyindole synthesized within the pineal gland. The hormone is secreted during the night and appears to play multiple roles within the human organism. The hormone contributes to the regulation of biological rhythms, may induce sleep, has strong antioxidant action and appears to contribute to the protection of the organism from carcinogenesis and neurodegenerative disorders. At a therapeutic level as well as in prevention, melatonin is used for the management of sleep disorders and jet lag, for the resynchronization of circadian rhythms in situations such as blindness and shift work, for its preventive action in the development of cancer, as additive therapy in cancer and as therapy for preventing the progression of Alzheimer's disease and other neurodegenerative disorders.

A review of the molecular aspects of melatonin's anti-inflammatory actions: recent insights and new perspectives

Melatonin is a highly evolutionary conserved endogenous molecule that is mainly produced by the pineal gland, but also by other nonendocrine organs, of most mammals including man. In the recent years, a variety of anti-inflammatory and antioxidant effects have been observed when melatonin is applied exogenously under both in vivo and in vitro conditions. A number of studies suggest that this indole may exert its anti-inflammatory effects through the regulation of different molecular pathways. It has been documented that melatonin inhibits the expression of the isoforms of inducible nitric oxide synthase and cyclooxygenase and limits the production of excessive amounts of nitric oxide, prostanoids, and leukotrienes, as well as other mediators of the inflammatory process such as cytokines, chemokines, and adhesion molecules. Melatonin's anti-inflammatory effects are related to the modulation of a number of transcription factors such as nuclear factor kappa B, hypoxia-inducible factor, nuclear factor erythroid 2-related factor 2, and others. Melatonin's effects on the DNA-binding capacity of transcription factors may be regulated through the inhibition of protein kinases involved in signal transduction, such as mitogen-activated protein kinases. This review summarizes recent research data focusing on the modulation of the expression of different inflammatory mediators by melatonin and the effects on cell signaling pathways responsible for the indole's anti-inflammatory activity. Although there are a numerous published reports that have analyzed melatonin's anti-inflammatory properties, further studies are necessary to elucidate its complex regulatory mechanisms in different cellular types and tissues.