Melatonin reduces oxidative stress in erythrocytes and plasma of senescence-accelerated mice

Prenatal exposure to ethion caused maternal and foetal toxicity in rats

Ethion is a class II moderately toxic organothiophosphate pesticide. The main objective of this study was to evaluate the maternal and foetal toxicity of ethion in rats. Pregnant rats were divided into 5 groups. Group I served as control. Group II, III, IV, and V were orally administered with 0.86, 1.71, 3.43, and 6.9 mg/kg of ethion respectively, from gestational day (GD) 6-19. Dams were sacrificed on GD 20. Maternal toxicity was assessed by body weight gain, foetal resorptions, oxidative stress, liver and kidney function tests, and histopathology. Foetal toxicity was assessed by physical status, gross, teratological and histopathological examination. Ethion caused dose-dependent reduction in maternal body weight gain, increased resorptions, and reduced gravid uterine weights. Elevated MDA levels and altered levels of GSH, SOD and catalase were recorded in pregnant dam serum and tissues. SGOT, SGPT, total bilirubin, urea, uric acid, and creatinine were elevated in ethion groups indicating liver and kidney toxicity. Histology of uterus revealed myometrial degeneration and mucosal gland atrophy in uterus of pregnant dams and degenerative changes in placenta. It showed histological alterations in liver, kidney, and lungs. There was reduction in the foetal body weights and placental weights, and degenerative changes in the foetal liver and kidney. Gross evaluation of foetuses showed subcutaneous hematoma. Skeletal evaluation showed partial ossification of skull bones, costal separation, and agenesis of tail vertebrae, sternebrae, metacarpals and metatarsals. The findings reveal that prenatal exposure to ethion caused maternal and foetal toxicity in rats.

Phylogenetic conservation of the interdependent homeostatic relationship of sleep regulation and redox metabolism

Sleep is an essential and evolutionarily conserved process that affects many biological functions that are also strongly regulated by cellular metabolism. The interdependence between sleep homeostasis and redox metabolism, in particular, is such that sleep deprivation causes redox metabolic imbalances in the form of over-production of ROS. Likewise (and vice versa), accumulation of ROS leads to greater sleep pressure. Thus, it is theorized that one of the functions of sleep is to act as the brain's "antioxidant" at night by clearing oxidation built up from daily stress of the active day phase. In this review, we will highlight evidence linking sleep homeostasis and regulation to redox metabolism by discussing (1) the bipartite role that sleep-wake neuropeptides and hormones have in redox metabolism through comparing cross-species cellular and molecular mechanisms, (2) the evolutionarily metabolic changes that accompanied the development of sleep loss in cavefish, and finally, (3) some of the challenges of uncovering the cellular mechanism underpinning how ROS accumulation builds sleep pressure and cellularly, how this pressure is cleared.

Adverse effect propensity: A new feature of Gulf War illness predicted by environmental exposures

A third of 1990-1 Gulf-deployed personnel developed drug/chemical-induced multisymptom illness, "Gulf War illness" (GWI). Veterans with GWI (VGWI) report increased drug/exposure adverse effects (AEs). Using previously collected data from a case-control study, we evaluated whether the fraction of exposures that engendered AEs ("AE Propensity") is increased in VGWI (it was); whether AE Propensity is related to self-rated "chemical sensitivity" (it did); and whether specific exposures "predicted" AE Propensity (they did). Pesticides and radiation exposure were significant predictors, with copper significantly "protective"-in the total sample (adjusted for GWI-status) and separately in VGWI and controls, on multivariable regression. Mitochondrial impairment and oxidative stress (OS) underlie AEs from many exposures irrespective of nominal specific mechanism. We hypothesize that mitochondrial toxicity and interrelated OS from pesticides and radiation position people on the steep part of the curve of mitochondrial impairment and OS versus symptom/biological disruption, amplifying impact of new exposures. Copper, meanwhile, is involved in critical OS detoxification processes.

Differential role of melatonin in healthy brain aging: a systematic review and meta-analysis of the SAMP8 model

The relationship between oxidative stress (OS) and cellular senescence (CS) is an important research topic because of the rapidly aging global population. Melatonin (MT) is associated with aging and plays a pivotal role in redox homeostasis, but its role in maintaining physiological stability in the brain (especially in OS-induced senescence) remains elusive. Here, we systematically reviewed the differential role of MT on OS-induced senescence in the SAMP8 mouse model. Major electronic databases were searched for relevant studies. Pooled mean differences (MDs)/standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated to estimate the effect size. Overall, 10 studies met the inclusion criteria. MT treatment was associated with the reduction of lipid peroxidation (SMD = -2.00, 95% CI [-2.91, -1.10]; p < 0.0001) and carbonylated protein (MD = -5.74, 95% CI [-11.03, -0.44]; p = 0.03), and with enhancement of the reduced-glutathione/oxidized-glutathione ratio (MD = 1.12, 95% CI [0.77, 1.47]; p < 0.00001). No differences were found in catalase and superoxide dismutase activities between MT-treated and vehicle-treated groups. Furthermore, nuclear-factor-κB, cyclin-dependent kinase-5, and p53 were regulated by MT administration. MT may improve physiological stability during aging by regulating interactions in brain senescence, but acts differentially on the antioxidant system.

Melatonin in Wine and Beer: Beneficial Effects

Melatonin is a hormone secreted in the pineal gland with several functions, especially regulation of circadian sleep cycle and the biological processes related to it. This review evaluates the bioavailability of melatonin and resulting metabolites, the presence of melatonin in wine and beer and factors that influence it, and finally the different benefits related to treatment with melatonin. When administered orally, melatonin is mainly absorbed in the rectum and the ileum; it has a half-life of about 0.45–1 h and is extensively inactivated in the liver by phase 2 enzymes. Melatonin (MEL) concentration varies from picograms to ng/mL in fermented beverages such as wine and beer, depending on the fermentation process. These low quantities, within a dietary intake, are enough to reach significant plasma concentrations of melatonin, and are thus able to exert beneficial effects. Melatonin has demonstrated antioxidant, anticarcinogenic, immunomodulatory and neuroprotective actions. These benefits are related to its free radical scavenging properties as well and the direct interaction with melatonin receptors, which are involved in complex intracellular signaling pathways, including inhibition of angiogenesis and cell proliferation, among others. In the present review, the current evidence on the effects of melatonin on different pathophysiological conditions is also discussed.

High Levels of β-Amyloid, Tau, and Phospho-Tau in Red Blood Cells as Biomarkers of Neuropathology in Senescence-Accelerated Mouse

Alzheimer's Disease (AD) is the most common Neurodegenerative Disease (ND), primarily characterised by neuroinflammation, neuronal plaques of β-amyloid (Aβ), and neurofibrillary tangles of hyperphosphorylated tau. α-Synuclein (α-syn) and its heteroaggregates with Aβ and tau have been recently included among the neuropathological elements of NDs. These pathological traits are not restricted to the brain, but they reach peripheral fluids as well. In this sense, Red Blood Cells (RBCs) are emerging as a good model to investigate the biochemical alterations of aging and NDs. Herein, the levels of homo- and heteroaggregates of ND-related proteins were analysed at different stages of disease progression. In particular, a validated animal model of AD, the SAMP8 (Senescence-Accelerated Mouse-Prone) and its control strain SAMR1 (Senescence-Accelerated Mouse-Resistant) were used in parallel experiments. The levels of the aforementioned proteins and of the inflammatory marker interleukin-1β (IL-1β) were examined in both brain and RBCs of SAMP8 and SAMR1 at 6 and 8 months. Brain Aβ, tau, and phospho-tau (p-tau) were higher in SAMP8 mice than in control mice and increased with AD progression. Similar accumulation kinetics were found in RBCs, even if slower. By contrast, α-syn and its heterocomplexes (α-syn-Aβ and α-syn-tau) displayed different accumulation kinetics between brain tissue and RBCs. Both brain and peripheral IL-1β levels were higher in SAMP8 mice, but increased sooner in RBCs, suggesting that inflammation might initiate at a peripheral level before affecting the brain. In conclusion, these results confirm RBCs as a valuable model for monitoring neurodegeneration, suggesting peripheral Aβ, tau, and p-tau as potential early biomarkers of AD.

The senescence-accelerated mouse prone 8 as a model for oxidative stress and impaired DNA repair in the male germ line

The discovery of a truncated base excision repair pathway in human spermatozoa mediated by OGG1 has raised questions regarding the effect of mutations in critical DNA repair genes on the integrity of the paternal genome. The senescence-accelerated mouse prone 8 (SAMP8) is a mouse model containing a suite of naturally occurring mutations resulting in an accelerated senescence phenotype largely mediated by oxidative stress, which is further enhanced by a mutation in theOgg1gene, greatly reducing the ability of the enzyme to excise 8-hydroxy,2′-deoxyguanosine (8OHdG) adducts. An analysis of the reproductive phenotype of the SAMP8 males revealed a high level of DNA damage in caudal epididymal spermatozoa as measured by the alkaline Comet assay. Furthermore, these lesions were confirmed to be oxidative in nature, as demonstrated by significant increases in 8OHdG adduct formation in the SAMP8 testicular tissue (P<0.05) as well as in mature spermatozoa (P<0.001) relative to a control strain (SAMR1). Despite this high level of oxidative DNA damage in spermatozoa, reactive oxygen species generation was not elevated and motility of spermatozoa was found to be similar to that for the control strain with the exception of progressive motility, which exhibited a slight but significant decline with advancing age (P<0.05). When challenged with Fenton reagents (H2O2and Fe2+), the SAMP8 spermatozoa demonstrated a highly increased susceptibility to formation of 8OHdG adducts compared with the controls (P<0.001). These data highlight the role of oxidative stress and OGG1-dependent base excision repair mechanisms in defining the genetic integrity of mammalian spermatozoa.

Royal jelly can diminish secondary neuronal damage after experimental spinal cord injury in rabbits

The aim of this experimental study was to investigate the neuroprotective effect of Royal jelly (RJ) on traumatic spinal cord injury (SCI). Twenty-one New Zealand male rabbits, weighing between 2.5 and 3.0 kg were divided into three groups: Sham (no drug or operation, n = 7), Control (laminectomy+single dose of 1 ml/kg saline orally, after trauma; n = 7) and RJ (laminectomy+100mg/kg RJ, orally, after trauma, n = 7). Laminectomy was perfor med at T10 and balloon catheter was applied extradurally for traumatic SCI. Four and 24h after surgery, rabbits were evaluated according to the Tarlov scoring system. Blood, cerebrospinal fluid and tissue sample from spinal cord were taken for measurements of antioxidant status or detection of apoptosis. Four hours after SCI, all animals in control or RJ treated groups became paraparesic. Significant improvement was observed in RJ treated group, 24h after SCI, with respect to control. Traumatic SCI led to increase in the lipid peroxidation and decrease enzymic or non-enzymic endogenous antioxidative defense systems, and increase in apoptotic cell numbers. RJ treatment mostly prevented lipid peroxidation and also augmented endogenous enzymic or non-enzymic antioxidative defense systems. Again, RJ treatment significantly decreased the apoptotic cell number induced by SCI.

Neurons from senescence-accelerated SAMP8 mice are protected against frailty by the sirtuin 1 promoting agents melatonin and resveratrol

The senescence-accelerated prone 8 (SAMP8) mouse strain shows early cognitive loss that mimics the deterioration of learning and memory in the elderly and is widely used as an animal model of aging. SAMP8 mouse brain suffers oxidative stress, as well as tau- and amyloid-related pathology. Mitochondrial dysfunction and the subsequent increase in cellular oxidative stress are central to the aging processes of the organism. Here, we examined the mitochondrial status of neocortical neurons cultured from SAMP8 and senescence-accelerated-resistant (SAMR1) mice. SAMP8 mouse mitochondria showed a reduced membrane potential and higher vulnerability to inhibitors and uncouplers than SAMR1 mitochondria. DL-buthionine-[S,R]-sulfoximine (BSO) caused greater oxidative damage in neurons from SAMP8 mice than in those from SAMR1 mice. This increased vulnerability, indicative of frailty-associated senescence, was protected by the anti-aging agents melatonin and resveratrol. The sirtuin 1 inhibitor, sirtinol, demonstrated that the neuroprotection against BSO was partially mediated by increased sirtuin 1 expression. Melatonin, like resveratrol, enhanced sirtuin 1 expression in neuron cultures of SAMR1 and SAMP8 mice. Therefore, a deficiency in the neuroprotection and longevity of the sirtuin 1 pathway in SAMP8 neurons may contribute to the early age-related brain damage in these mice. This supports the therapeutic use of sirtuin 1-enhancing agents against age-related nerve cell dysfunction and brain frailty.

The roles of melatonin and vitamin E plus selenium in prevention of oxidative stress induced by naloxone-precipitated withdrawal in heroin-addicted rats

The therapeutic effects of melatonin or vitamin E plus Se (vE + Se) on the restrain of the heroin withdrawal-induced oxidative stress were studied. For this, rats were divided into ten groups. The rats were injected by fixed or variable doses of heroin for 16 consecutive days, and naloxone was given 1 h after the last heroin injection. One hour after naloxone administration, some groups were treated with melatonin or vE + Se. After 1 h this, blood samples were taken, and the levels of malondialdehyde (MDA) and reduced glutathione (GSH) in whole blood, ascorbic acid, α-tocopherol, retinol, β-carotene, nitrite, nitrate, and ceruloplasmin levels in the serum were measured. Our findings showed that, naloxone administration precipitated the heroin withdrawal. This also increased the level of MDA and decreased the levels of GSH in blood. Melatonin or vE + Se administration prevented the rise in MDA levels and increased the GSH levels. On the other hand, there were some significant differences between α-tocopherol, retinol, β-carotene, nitrite, nitrate, and ceruloplasmin levels of experimental groups. Results of present study showed that heroin withdrawal increased the lipid peroxidation and depressed endogenous antioxidative systems. Additionally, melatonin or vE + Se administrations prevented lipid peroxidation and augmented endogenous antioxidant defense systems.

Effects of LED light spectra on oxidative stress and the protective role of melatonin in relation to the daily rhythm of the yellowtail clownfish, Amphiprion clarkii

The present study aimed to test the effects of melatonin on oxidative stress in the yellowtail clownfish, Amphiprion clarkii, as produced by light emitting diodes (LEDs): red, green, and blue. We investigated the effects of the different LEDs on oxidative stress by measuring the mRNA expression of arylalkylamine N-acetyltransferase (AANAT2), the expression and activities of antioxidant enzymes (superoxide dismutase, SOD (EC 1.15.1.1); and catalase, CAT (EC 1.11.1.6)), and plasma H2O2 and plasma melatonin levels. In red light, the expression of AANAT2, SOD, and CAT mRNA was significantly higher than those under the other light spectra. SOD and CAT activities and plasma H2O2 and melatonin levels were also significantly higher for the red spectra than those for the other light spectra. These results indicate that red light induces oxidative stress. To investigate the effects of melatonin on oxidative stress, we injected melatonin into live fish (in vivo) or treated cultured pineal organ (in vitro) with melatonin. We found that AANAT2, SOD, and CAT mRNA expression levels, SOD and CAT activities, and plasma H2O2, lipid peroxidation (LPO) and melatonin levels were significantly lower than those for the controls. Therefore, our results indicate that red light induces oxidative stress and melatonin plays the role of a strong antioxidant in yellowtail clownfish.

Ameliorative action of melatonin on oxidative damage induced by atrazine toxicity in rat erythrocytes

Excessive generation of reactive oxygen species (ROS) can induce oxidative damage to vital cellular molecules and structures including DNA, lipids, proteins, and membranes. Recently, melatonin has attracted attention because of their free radical scavenging and antioxidant properties. The aim of this study was to evaluate the possible protective role of melatonin against atrazine-induced oxidative stress in rat erythrocytes in vivo. Adult male albino rats of Wistar strain were randomly divided into four groups. Control group received isotonic saline; melatonin (10 mg/kg bw/day) group; atrazine (300 mg/kg of bw/day) group; atrazine + melatonin group. Oral administration of atrazine and melatonin was given daily for 21 days. Oxidative stress was assessed by determining the glutathione (GSH) and malondialdehyde (MDA) level, and alteration in antioxidant enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione-S-transferase (GST), and glucose-6-phosphate dehydrogenase (G-6-PD) in the erythrocytes of normal and experimental animals. A significant increase in the MDA levels and decrease in the GSH was observed in the atrazine treated animals (P < 0.05). Also, significant increase in the activities of SOD, CAT, GPx, and GST were observed in atrazine treated group compared to controls (P < 0.05). Moreover, significant decrease in protein, total lipids, cholesterol, and phospholipid content in erythrocyte membrane were demonstrated in atrazine treated rats. Administration of atrazine significantly inhibits the activities of G-6-PD and membrane ATPases such as Na(+)/K(+)-ATPase, Mg(2+)-ATPase, and Ca(2+)-ATPase (P < 0.05). Scanning electron microscopic (SEM) examination of erythrocytes revealed morphological alterations in the erythrocytes of atrazine treated rats. Furthermore, supplementation of melatonin significantly modulates the atrazine-induced changes in LPO level, total lipids, total ATPases, GSH, and antioxidant enzymes in erythrocytes. In conclusion, the increase in oxidative stress markers and the concomitant alterations in antioxidant defense system indicate the role of oxidative stress in erythrocytes of atrazine-induced damage. Moreover, melatonin shows a protective role against atrazine-induced oxidative damage in rat erythrocytes.

Protective role of melatonin on oxidative stress status and RNA expression in cerebral cortex and cerebellum of AbetaPP transgenic mice after chronic exposure to aluminum

Aluminum (Al) has been associated with pro-oxidant effects, as well as with various serious neurodegenerative diseases such as Alzheimer's disease (AD). On the other hand, melatonin (Mel) is a known antioxidant, which can directly act as free radical scavenger, or indirectly by inducing the expression of some genes linked to the antioxidant defense. In this study, 5-month-old AssPP female transgenic (Tg2576) (Tg) and wild-type mice were fed with Al lactate supplemented in the diet (1 mg Al/g diet). Concurrently, animals received oral Mel (10 mg/kg) until the end of the study at 11 months of age. Four treatment groups were included for both Tg and wild-type mice: control, Al only, Mel only, and Al + Mel. At the end of the treatment period, cortex and cerebellum were removed and processed to examine the following oxidative stress markers: reduced glutathione, oxidized glutathione, cytosolic Cu-Zn superoxide dismutase (SOD1), glutathione reductase (GR), glutathione peroxidase, catalase (CAT), and thiobarbituric acid reactive substances. Moreover, the gene expression of SOD1, GR, and CAT was evaluated by real-time RT-PCR. The biochemical changes observed in cortex and cerebellum suggest that Al acted as a pro-oxidant agent. Melatonin exerted an antioxidant action by increasing the mRNA levels of the enzymes SOD1, CAT, and GR evaluated in presence of Al and Mel, independently on the animal model.

Oxidative stress status and RNA expression in hippocampus of an animal model of Alzheimer's disease after chronic exposure to aluminum

It is well established that aluminum (Al) is a neurotoxic agent that induces the production of free radicals in brain. Accumulation of free radicals may cause degenerative events of aging such as Alzheimer's disease. On the other hand, melatonin (Mel) is a known antioxidant, which can directly act as free radical scavenger, or indirectly by inducing the expression of some genes linked to the antioxidant defense. In this study, AbetaPP female transgenic (Tg2576) (Tg) and wild-type mice (5 months of age) were fed with Al lactate supplemented in the diet (1 mg Al/g diet). Simultaneously, animals received oral Mel (10 mg/kg) dissolved in tap water until the end of the study at 11 months of age. Four treatment groups were included for both Tg and wild-type mice: control, Al only, Mel only, and Al+Mel. At the end of the period of treatment, hippocampus was removed and processed to examine the following oxidative stress markers: reduced glutathione (GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), and thiobarbituric acid reactive substances (TBARS). Moreover, the gene expression of Cu-ZnSOD, GR, and CAT was evaluated by real-time RT-PCR. Aluminum concentration in hippocampus was also determined. The biochemical changes observed in this tissue suggest that Al acts as a pro-oxidant agent. Melatonin exerts an antioxidant action by increasing the mRNA levels of the antioxidant enzymes SOD, CAT, and GR evaluated in presence of Al and Mel, with independence of the animal model.

Dantrolene can reduce secondary damage after spinal cord injury

The aim of this experimental study was to investigate the possible protective effects of dantrolene on traumatic spinal cord injury (SCI). Twenty-four New Zealand rabbits were divided into three groups: Sham (no drug or operation, n = 8), Control (SCI + 1 mL saline intraperitoneally (i.p.), n = 8), and DNT (SCI + 10 mg/kg dantrolene in 1 mL, i.p., n = 8). Laminectomy was performed at T10 and balloon catheter was applied extradurally. Four and 24 h after surgery, rabbits were evaluated according to the Tarlov scoring system. Blood, cerebrospinal fluid and tissue sample from spinal cord were taken for measurements of antioxidant status or detection of apoptosis. After 4 h SCI, all animals in control or DNT-treated groups became paraparesic. Significant improvement was observed in DNT-treated group, 24 h after SCI, with respect to control. Traumatic SCI led to an increase in the lipid peroxidation and a decrease in enzymic or non-enzymic endogenous antioxidative defense systems, and increase in apoptotic cell numbers. DNT treatment prevented lipid peroxidation and augmented endogenous enzymic or non-enzymic antioxidative defense systems. Again, DNT treatment significantly decreased the apoptotic cell number induced by SCI. In conclusion, experimental results observed in this study suggest that treatment with dantrolene possess potential benefits for traumatic SCI.

Melatonin and breast cancer: cellular mechanisms, clinical studies and future perspectives

Recent studies have suggested that the pineal hormone melatonin may protect against breast cancer, and the mechanisms underlying its actions are becoming clearer. Melatonin works through receptors and distinct second messenger pathways to reduce cellular proliferation and to induce cellular differentiation. In addition, independently of receptors melatonin can modulate oestrogen-dependent pathways and reduce free-radical formation, thus preventing mutation and cellular toxicity. The fact that melatonin works through a myriad of signalling cascades that are protective to cells makes this hormone a good candidate for use in the clinic for the prevention and/or treatment of cancer. This review summarises cellular mechanisms governing the action of melatonin and then considers the potential use of melatonin in breast cancer prevention and treatment, with an emphasis on improving clinical outcomes.

Does dexmedetomidine reduce secondary damage after spinal cord injury? An experimental study

The aim of this experimental study was to investigate the possible protective effect of dexmedetomidine (DEX) on traumatic spinal cord injury (SCI). Twenty-two New Zealand rabbits were divided into three groups: sham (no drug or operation, n = 6), Control [SCI + single dose of 1 mL saline intraperitoneally (i.p), after trauma; n = 8] and DEX (SCI + 1 microg/kg dexmedetomidine in 1 mL, i.p, after trauma, n = 8). Laminectomy was performed at T10 and balloon angioplasty catheter was applied extradurally. Four and 24 h after surgery, rabbits were evaluated by an independent observer according to the Tarlov scoring system. Blood, cerebrospinal fluid (CSF), tissue samples from spinal cord were taken for biochemical and histopathological evaluations. After 4 h of SCI, all animals in control or DEX treated groups became paraparesic. On the other hand, 24 h after SCI, partial improvements were observed in both control and DEX treated groups. Traumatic SCI leads to increase in the lipid peroxidation and decreases enzymatic or nonenzymatic endogenous antioxidative defense systems. Again, SCI leads to apoptosis in spinal cord. DEX treatment slightly prevented lipid peroxidation and augmented endogenous antioxidative defense systems in CSF or spinal cord tissue, but failed to prevent apoptosis or neurodeficit after traumatic SCI. Therefore, it could be suggested that treatment with dexmedetomidine does not produce beneficial results in SCI.

Antioxidative role of melatonin in organophosphate toxicity in rats

Previous studies revealed that oxidative stress could be an important component of the mechanism of organophosphate (OP) compound toxicity. The aim of the present study was to investigate both prophylactic and therapeutic effects of melatonin against fenthion-induced oxidative stress in rats. Therefore, we determined the changes in the levels of reduced glutathione (GSH) and malondialdehyde (MDA) in the whole blood, brain, pectoral muscle, liver, lung, heart, kidney, pancreas, and jejunum. Also, the changes in the levels of serum nitrite and nitrate, ascorbic acid, retinal, b-carotene, and ceruloplasmin were measured. In addition, activities of enzymatic antioxidants superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) in erythrocyte of normal and experimental animals were measured. It was found that fenthion administration increased the levels of MDA in all tissues and decreased or increased the levels of GSH in some tissues. In comparison to nitrate, nitrite and ascorbic acid levels in the serum of experimental groups, there was no significant difference between groups. However, fenthion toxicity led to decrease in retinol and beta-carotene levels; melatonin administration significantly prevented this decrease. Serum ceruloplasmin level was increased due to fenthion administration, but prophylactic and therapeutic melatonin administration inhibited the increase in ceruloplasmin level of serum. There was no significant change in SOD levels in melatonin-administered groups. Melatonin modulates the fenthion-induced changes in the activities of GPx and CAT. In conclusion, the results of the current study revealed that OP toxicity, induced by fenthion, activated oxidant systems in all antioxidant systems in some tissues. Melatonin administration led to a marked increase in antioxidant activity and inhibited lipid peroxidation in most of tissues.

Melatonin reduces uranium-induced nephrotoxicity in rats

The protective role of exogenous melatonin on U-induced nephrotoxicity was investigated in rats. Animals were given single doses of uranyl acetate dihydrate (UAD) at 5 mg/kg (subcutaneous), melatonin at 10 or 20 mg/kg (intraperitoneal), and UAD (5 mg/kg) plus melatonin (10 or 20 mg/kg), or vehicle (control group). In comparison with the UAD-treated group only, significant beneficial changes were noted in some urinary and serum parameters of rats concurrently exposed to UAD and melatonin. The increase of U excretion after UAD administration was accompanied by a significant reduction in the renal content of U when melatonin was given at a dose of 20 mg/kg. Melatonin also reduced the severity of the U-induced histological alterations in kidney. In renal tissue, the activity of the superoxide dismutase (SOD) and the thiobarbituric acid reactive substances (TBARS) levels increased significantly as a result of UAD exposure. Following UAD administration, oxidative stress markers in erythrocytes showed a reduction in SOD activity and an increase in TBARS levels, which were significantly restored by melatonin administration. In plasma, reduced glutathione (GSH) and its oxidized form (GSSG) were also altered in UAD-exposed rats. However, only the GSSG/GSH ratio was restored to control levels after melatonin treatment. Oxidative damage was observed in kidneys. Melatonin administration partially restored these adverse effects. It is concluded that melatonin offers some benefit as a potential agent to treat acute U-induced nephrotoxicity.

Markers of oxidative stress in erythrocytes during aging in humans

The correlation between antioxidant capacity and oxidative damage during aging has been reported in several tissues in different species; however, data on changes of oxidative stress markers in plasma and erythrocytes of healthy populations during aging are few and sometimes contradictory. Since antioxidant capacity of the plasma is related to dietary intake of antioxidants, it is important to study the correlation between antioxidant capacity of the plasma and markers of oxidative stress in different populations. In the present study we report the age-dependent alteration in erythrocyte malondialdehyde (MDA), intracellular-reduced glutathione (GSH), and membrane sulphydryl (SH) groups in the Indian population and also correlate these parameters with total plasma antioxidant potential. We show an age-dependent increase in erythrocyte MDA level and a decrease in GSH and membrane -SH group concentration. The alterations in these parameters correlated significantly with total antioxidant capacity of the plasma. We observe a higher oxidative stress in the Indian population compared to values reported for European subjects emphasizing the need to establish age-dependent reference values for oxidative stress markers in different populations and in studies involving their role in different disease conditions.

Chronic melatonin treatment reduces the age-dependent inflammatory process in senescence-accelerated mice

It is hypothesized that, besides increased free radical production, aging is a process also related to inflammation. Thus, female and male senescence-accelerated (SAMP8) and senescence-resistant (SAMR1) mice of 5 and 10 months of age were studied to assess this hypothesis. Plasma from these mice was processed to determine nitric oxide (NO), and pro-inflammatory [interleukin (IL)-1beta, IL-2, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and granulocyte-macrophage colony-stimulating factor] and anti-inflammatory (IL-4, IL-5 and IL-10) cytokines. The results show the presence of an age-dependent increase in IFN-gamma and TNF-alpha and a reduction in IL-2 levels, with minor changes in the remaining cytokines. Moreover, age was associated with a significant increase in NO levels. Chronic melatonin administration between 1 and 10 months of age counteracted the age-dependent production of pro-inflammatory cytokines and NO, reducing them to the levels found at 5 months of age. Melatonin also reduced the levels of the anti-inflammatory cytokines. The results of this study suggest the existence of an inflammatory process during aging and further support that melatonin behaves as an essential molecule against aging, for its anti-inflammatory properties together with its antioxidative role reported elsewhere.

Chronic administration of melatonin reduces cerebral injury biomarkers in SAMP8

Certain effects of melatonin on senescence were investigated. The experimental model used was 10-month-old senescence-accelerated mouse prone 8 (SAMP8). The mice in the experiment were administered melatonin (10 mg/kg) from the age of 1 month. Results showed that chronic administration of melatonin decreased cell loss in the cerebral cortex and reduced oxidative damage in protein and lipids. There are several studies suggesting that the activation of the cdk5/p35 pathway at its cleavage to cdk5/p25 may play a role in hyperphosphorylation of tau during aging and neurodegenerative diseases. Melatonin not only reduced the cerebral aging disturbances, but also prevented tau hyperphosphorylation present in the experimental model used in this study. Melatonin reduced cdk5 expression, as well as the cleavage of p35 to p25. The other tau kinase studied, GSK3beta, showed a reduction in this activity in comparison with SAMP8 nontreated SAMP8. These data indicate that melatonin possesses neuroprotective properties against cerebral damage gated to senescence. Moreover, these data suggest that the cdk5/GSKbeta signaling cascade has a potential role as a target for neurodegenerative diseases related to aging.