Age-associated neurodegeneration and oxidative damage to lipids, proteins and DNA

Salvia miltiorrhiza: A source for anti-Alzheimer's disease drugs

CONTEXT

Alzheimer's disease (AD) is a devastating neurodegenerative disorder that affects millions of elderly people worldwide. However, no efficient therapeutic method for AD has yet been developed. Recently, Salvia miltiorrhiza Bunge (Lamiaceae), a well-known traditional Chinese medicine which is widely used for treating cardio-cerebrovascular, exerts multiple neuroprotective effects and is attracting increased attention for the treatment of AD.

OBJECTIVE

The objective of this study is to discuss the neuroprotective effects and neurogenesis-inducing activities of S. miltiorrhiza components.

METHODS

A detailed search using major electronic search engines (such as Pubmed, ScienceDirect, and Google Scholar) was undertaken with the search terms: Salvia miltiorrhiza, the components of S. miltiorrhiza such as salvianolic acid B, salvianolic acid A, danshensu, tanshinone I, tanshinone IIA, cryptotanshinone, dihydrotanshinone, and neuroprotection.

RESULTS

Salvia miltiorrhiza components exert multiple neuroprotective potentials relevant to AD, such as anti-amyloid-β, antioxidant, anti-apoptosis, acetylcholinesterase inhibition, and anti-inflammation. Moreover, S. miltiorrhiza promotes neurogenesis of neural progenitor cells/stem cells in vitro and in vivo.

CONCLUSIONS

The properties of S. miltiorrhiza indicate their therapeutic potential in AD via multiple mechanisms. In addition, S. miltiorrhiza provides lead compounds for developing new drugs against AD.

Oxidative stress, bone marrow failure, and genome instability in hematopoietic stem cells

Reactive oxygen species (ROS) can be generated by defective endogenous reduction of oxygen by cellular enzymes or in the mitochondrial respiratory pathway, as well as by exogenous exposure to UV or environmental damaging agents. Regulation of intracellular ROS levels is critical since increases above normal concentrations lead to oxidative stress and DNA damage. A growing body of evidence indicates that the inability to regulate high levels of ROS leading to alteration of cellular homeostasis or defective repair of ROS-induced damage lies at the root of diseases characterized by both neurodegeneration and bone marrow failure as well as cancer. That these diseases may be reflective of the dynamic ability of cells to respond to ROS through developmental stages and aging lies in the similarities between phenotypes at the cellular level. This review summarizes work linking the ability to regulate intracellular ROS to the hematopoietic stem cell phenotype, aging, and disease.

GIT2 Acts as a Systems-Level Coordinator of Neurometabolic Activity and Pathophysiological Aging

Aging represents one of the most complicated and highly integrated somatic processes. Healthy aging is suggested to rely upon the coherent regulation of hormonal and neuronal communication between the central nervous system and peripheral tissues. The hypothalamus is one of the main structures in the body responsible for sustaining an efficient interaction between energy balance and neurological activity and therefore likely coordinates multiple systems in the aging process. We previously identified, in hypothalamic and peripheral tissues, the G protein-coupled receptor kinase interacting protein 2 (GIT2) as a stress response and aging regulator. As metabolic status profoundly affects aging trajectories, we investigated the role of GIT2 in regulating metabolic activity. We found that genomic deletion of GIT2 alters hypothalamic transcriptomic signatures related to diabetes and metabolic pathways. Deletion of GIT2 reduced whole animal respiratory exchange ratios away from those related to primary glucose usage for energy homeostasis. GIT2 knockout (GIT2KO) mice demonstrated lower insulin secretion levels, disruption of pancreatic islet beta cell mass, elevated plasma glucose, and insulin resistance. High-dimensionality transcriptomic signatures from islets isolated from GIT2KO mice indicated a disruption of beta cell development. Additionally, GIT2 expression was prematurely elevated in pancreatic and hypothalamic tissues from diabetic-state mice (db/db), compared to age-matched wild type (WT) controls, further supporting the role of GIT2 in metabolic regulation and aging. We also found that the physical interaction of pancreatic GIT2 with the insulin receptor and insulin receptor substrate 2 was diminished in db/db mice compared to WT mice. Therefore, GIT2 appears to exert a multidimensional "keystone" role in regulating the aging process by coordinating somatic responses to energy deficits.

Ginsenoside Rb1 prevents hypoxia-reoxygenation-induced apoptosis in H9c2 cardiomyocytes via an estrogen receptor-dependent crosstalk among the Akt, JNK, and ERK 1/2 pathways using a label-free quantitative proteomics analysis

Rb1 prevents H/R-induced apoptosis of H9c2 cells via an estrogen receptor-dependent crosstalk among the Akt, JNK, and ERK 1/2 pathways.

Medical genetics-based drug repurposing for Alzheimer's disease

Alzheimer's disease (AD) is a disease that threatens the elderly. No efficient therapeutic method is currently available to combat AD. Drug repurposing has provided a new route for AD drug discovery, and medical genetics has shown potential in target-based drug repurposing. We compared AD-associated genes with approved drug targets and found that three are targeted by 23 approved drugs. Thus, these drugs may be used to treat AD according to the medical genetic information of the targets. In vitro and in vivo experiments revealed that four drugs, all of which are angiotensin-converting enzyme (ACE) inhibitors, had potential to treat AD.

Immunosuppressive capabilities of mesenchymal stromal cells are maintained under hypoxic growth conditions and after gamma irradiation

BACKGROUND AIMS

The discovery of regenerative and immunosuppressive capacities of mesenchymal stromal cells (MSCs) raises hope for patients with tissue-damaging or severe, treatment-refractory autoimmune disorders. We previously presented a method to expand human MSCs in a bioreactor under standardized Good Manufacturing Practice conditions. Now we characterized the impact of critical treatment conditions on MSCs with respect to immunosuppressive capabilities and proliferation.

METHODS

MSC proliferation and survival after γ irradiation were determined by 5-carboxyfluorescein diacetate N-succinimidyl ester and annexinV/4',6-diamidino-2-phenylindole (DAPI) staining, respectively. T-cell proliferation assays were used to assess the effect of γ irradiation, passaging, cryopreservation, post-thaw equilibration time and hypoxia on T-cell suppressive capacities of MSCs. Quantitative polymerase chain reaction and β-galactosidase staining served as tools to investigate differences between immunosuppressive and non-immunosuppressive MSCs.

RESULTS

γ irradiation of MSCs abrogated their proliferation while vitality and T-cell inhibitory capacity were preserved. Passaging and long cryopreservation time decreased the T-cell suppressive function of MSCs, and postthaw equilibration time of 5 days restored this capability. Hypoxic culture markedly increased MSC proliferation without affecting their T-cell-suppressive capacity and phenotype. Furthermore, T-cell suppressive MSCs showed higher CXCL12 expression and less β-galactosidase staining than non-suppressive MSCs.

DISCUSSION

We demonstrate that γ irradiation is an effective strategy to abrogate MSC proliferation without impairing the cells' immunosuppressive function. Hypoxia significantly enhanced MSC expansion, allowing for transplantation of MSCs with low passage number. In summary, our optimized MSC expansion protocol successfully addressed the issues of safety and preservation of immunosuppressive MSC function after ex vivo expansion for therapeutic purposes.

Electrochemically reduced water protects neural cells from oxidative damage

Aging-related neurodegenerative disorders are closely associated with mitochondrial dysfunction and oxidative stresses and their incidence tends to increase with aging. Brain is the most vulnerable to reactive species generated by a higher rate of oxygen consumption and glucose utilization compared to other organs. Electrochemically reduced water (ERW) was demonstrated to scavenge reactive oxygen species (ROS) in several cell types. In the present study, the protective effect of ERW against hydrogen peroxide (H₂O₂) and nitric oxide (NO) was investigated in several rodent neuronal cell lines and primary cells. ERW was found to significantly suppress H₂O₂ (50–200 μM) induced PC12 and SFME cell deaths. ERW scavenged intracellular ROS and exhibited a protective effect against neuronal network damage caused by 200 μM H₂O₂ in N1E-115 cells. ERW significantly suppressed NO-induced cytotoxicity in PC12 cells despite the fact that it did not have the ability to scavenge intracellular NO. ERW significantly suppressed both glutamate induced Ca²⁺ influx and the resulting cytotoxicity in primary cells. These results collectively demonstrated for the first time that ERW protects several types of neuronal cells by scavenging ROS because of the presence of hydrogen and platinum nanoparticles dissolved in ERW.

Shortened telomere length in white matter oligodendrocytes in major depression: potential role of oxidative stress

Telomere shortening is observed in peripheral mononuclear cells from patients with major depressive disorder (MDD). Whether this finding and its biological causes impact the health of the brain in MDD is unknown. Brain cells have differing vulnerabilities to biological mechanisms known to play a role in accelerating telomere shortening. Here, two glia cell populations (oligodendrocytes and astrocytes) known to have different vulnerabilities to a key mediator of telomere shortening, oxidative stress, were studied. The two cell populations were separately collected by laser capture micro-dissection of two white matter regions shown previously to demonstrate pathology in MDD patients. Cells were collected from brain donors with MDD at the time of death and age-matched psychiatrically normal control donors (N = 12 donor pairs). Relative telomere lengths in white matter oligodendrocytes, but not astrocytes, from both brain regions were significantly shorter for MDD donors as compared to matched control donors. Gene expression levels of telomerase reverse transcriptase were significantly lower in white matter oligodendrocytes from MDD as compared to control donors. Likewise, the gene expression of oxidative defence enzymes superoxide dismutases (SOD1 and SOD2), catalase (CAT) and glutathione peroxidase (GPX1) were significantly lower in oligodendrocytes from MDD as compared to control donors. No such gene expression changes were observed in astrocytes from MDD donors. These findings suggest that attenuated oxidative stress defence and deficient telomerase contribute to telomere shortening in oligodendrocytes in MDD, and suggest an aetiological link between telomere shortening and white matter abnormalities previously described in MDD.

Resveratrol in vitro amelioratestert-butyl hydroperoxide-induced alterations in erythrocyte membranes from young and older humans

Implication of reactive oxygen species/oxidative stress has been readily reported in etiology of aging and related manifestations. Plasma membrane as a regulator of numerous aspects of cell physiology including cell–cell interaction, solute transport, and signal transduction, provides structural integrity to the cells. The aim of the present study was to determine the effect of resveratrol administration in vitro, to evaluate the biological effect of this phytoalexin in oxidatively injured erythrocytes during aging. This study, carried out on 91 normal healthy subjects, provides experimental evidence that erythrocytes have increased oxidative damage with age. In vitro administration of resveratrol significantly attenuated deleterious effects of oxidative injury in erythrocytes from humans of all ages.

ATP insertion opposite 8-oxo-deoxyguanosine by Pol4 mediates error-free tolerance in Schizosaccharomyces pombe

7,8-Dihydro-8-oxo-deoxyguanosine (8oxodG) is a highly premutagenic DNA lesion due to its ability to mispair with adenine. Schizosaccharomyces pombe lacks homologs for relevant enzymes that repair 8oxodG, which suggests that this lesion could be persistent and must be tolerated. Here we show that SpPol4, the unique PolX in fission yeast, incorporates ATP opposite 8oxodG almost exclusively when all nucleotides (ribos and deoxys) are provided at physiological concentrations. Remarkably, this SpPol4-specific reaction could also occur during the NHEJ of DSBs. In cell extracts, misincorporation of ATP opposite 8oxodG was shown to be SpPol4-specific, although RNase H2 efficiently recognized the 8oxodG:AMP mispair to remove AMP and trigger error-free incorporation of dCTP. These data are the first evidence that ribonucleotides can be used safely for 8oxodG tolerance, suggesting that insertion of the highly abundant ATP substrate could be beneficial to promote efficient and error-free repair of 8oxodG-associated DSBs. Moreover, we demonstrate that purified SpPol4 uses 8oxo-dGTP and 8oxo-GTP as substrates for DNA polymerization, although with poor efficiency compared to the incorporation of undamaged nucleotides opposite either 8oxodG or undamaged templates. This suggests that SpPol4 is specialized in tolerating 8oxodG as a DNA template, without contributing significantly to the accumulation of this lesion in the DNA.

Removal efficiency of radioactive cesium and iodine ions by a flow-type apparatus designed for electrochemically reduced water production

The Fukushima Daiichi Nuclear Power Plant accident on March 11, 2011 attracted people’s attention, with anxiety over possible radiation hazards. Immediate and long-term concerns are around protection from external and internal exposure by the liberated radionuclides. In particular, residents living in the affected regions are most concerned about ingesting contaminated foodstuffs, including drinking water. Efficient removal of radionuclides from rainwater and drinking water has been reported using several pot-type filtration devices. A currently used flow-type test apparatus is expected to simultaneously provide radionuclide elimination prior to ingestion and protection from internal exposure by accidental ingestion of radionuclides through the use of a micro-carbon carboxymethyl cartridge unit and an electrochemically reduced water production unit, respectively. However, the removability of radionuclides from contaminated tap water has not been tested to date. Thus, the current research was undertaken to assess the capability of the apparatus to remove radionuclides from artificially contaminated tap water. The results presented here demonstrate that the apparatus can reduce radioactivity levels to below the detection limit in applied tap water containing either 300 Bq/kg of ¹³⁷Cs or 150 Bq/kg of ¹²⁵I. The apparatus had a removal efficiency of over 90% for all concentration ranges of radio–cesium and –iodine tested. The results showing efficient radionuclide removability, together with previous studies on molecular hydrogen and platinum nanoparticles as reactive oxygen species scavengers, strongly suggest that the test apparatus has the potential to offer maximum safety against radionuclide-contaminated foodstuffs, including drinking water.

Mitochondrial biogenesis-associated factors underlie the magnitude of response to aerobic endurance training in rats

Trainability is important in elite sport and in recreational physical activity, and the wide range for response to training is largely dependent on genotype. In this study, we compare a newly developed rat model system selectively bred for low and high gain in running distance from aerobic training to test whether genetic segregation for trainability associates with differences in factors associated with mitochondrial biogenesis. Low response trainer (LRT) and high response trainer (HRT) rats from generation 11 of artificial selection were trained five times a week, 30 min per day for 3 months at 70 % VO2max to study the mitochondrial molecular background of trainability. As expected, we found significant differential for the gain in running distance between LRT and HRT groups as a result of training. However, the changes in VO2max, COX-4, redox homeostasis associated markers (reactive oxygen species (ROS)), silent mating-type information regulation 2 homolog (SIRT1), NAD(+)/NADH ratio, proteasome (R2 subunit), and mitochondrial network related proteins such as mitochondrial fission protein 1 (Fis1) and mitochondrial fusion protein (Mfn1) suggest that these markers are not strongly involved in the differences in trainability between LRT and HRT. On the other hand, according to our results, we discovered that differences in basal activity of AMP-activated protein kinase alpha (AMPKα) and differential changes in aerobic exercise-induced responses of citrate synthase, carbonylated protein, peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1-α), nuclear respiratory factor 1 (NRF1), mitochondrial transcription factor A (TFAM), and Lon protease limit trainability between these selected lines. From this, we conclude that mitochondrial biogenesis-associated factors adapt differently to aerobic exercise training in training sensitive and training resistant rats.

Mitochondrial biogenesis-associated factors underlie the magnitude of response to aerobic endurance training in rats

Trainability is important in elite sport and in recreational physical activity, and the wide range for response to training is largely dependent on genotype. In this study, we compare a newly developed rat model system selectively bred for low and high gain in running distance from aerobic training to test whether genetic segregation for trainability associates with differences in factors associated with mitochondrial biogenesis. Low response trainer (LRT) and high response trainer (HRT) rats from generation 11 of artificial selection were trained five times a week, 30 min per day for 3 months at 70 % VO2max to study the mitochondrial molecular background of trainability. As expected, we found significant differential for the gain in running distance between LRT and HRT groups as a result of training. However, the changes in VO2max, COX-4, redox homeostasis associated markers (reactive oxygen species (ROS)), silent mating-type information regulation 2 homolog (SIRT1), NAD(+)/NADH ratio, proteasome (R2 subunit), and mitochondrial network related proteins such as mitochondrial fission protein 1 (Fis1) and mitochondrial fusion protein (Mfn1) suggest that these markers are not strongly involved in the differences in trainability between LRT and HRT. On the other hand, according to our results, we discovered that differences in basal activity of AMP-activated protein kinase alpha (AMPKα) and differential changes in aerobic exercise-induced responses of citrate synthase, carbonylated protein, peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1-α), nuclear respiratory factor 1 (NRF1), mitochondrial transcription factor A (TFAM), and Lon protease limit trainability between these selected lines. From this, we conclude that mitochondrial biogenesis-associated factors adapt differently to aerobic exercise training in training sensitive and training resistant rats.

Notoginsenoside R1-mediated neuroprotection involves estrogen receptor-dependent crosstalk between Akt and ERK1/2 pathways: a novel mechanism of Nrf2/ARE signaling activation

Notoginsenoside R1 (NGR1), a novel phytoestrogen isolated from Panax notoginseng, has antioxidant and anti-apoptotic properties. Oxidative stress plays a pivotal role in neurodegenerative diseases. To mimic oxidative stress in neurons and explore the neuroprotection of NGR1, H₂O₂-induced neurotoxicity in NGF-induced differentiation of PC12 cells was used. In this study, NGR1 preconditioning provided neuroprotective effects via suppressing H₂O₂-induced the intracellular ROS accumulation, the increase in the product of lipid peroxidation (MDA), protein oxidation (protein carbonyl), and DNA fragmentation (8-OHdG), and mitochondrial membrane depolarization as well as caspase-3 activation. Moreover, NGR1 treatment alone potently increased the nuclear translocation of Nrf2, augmented ARE enhancer activity, and upregulated the expression and activity of phase II antioxidant enzymes including HO-1, NQO-1, and γ-GCSc. NGR1 could also increase the ERE activity and activate Akt and ERK1/2 pathways. NGR1-mediated activation of Nrf2/ARE signaling and neuroprotection were abolished by genetic silencing of Nrf2 using siRNA or the pharmacological blockade of estrogen receptors using ICI-182780, and partially inhibited by Akt siRNA or ERK siRNA transfection. In addition, the phosphorylation of ERK1/2 mediated by NGR1 was markedly inhibited in PC12 cells transfected with Akt siRNA. On the contrary, ERK1/2 siRNA transfection hardly had any effect on the phosphorylation of Akt mediated by NGR1. NGR1-mediated activation of Akt and ERK1/2 pathways was blocked by ICI-182780. In conclusion, NGR1 provided neuroprotection via inducing an estrogen receptor-dependent crosstalk between Akt and ERK1/2 pathways, subsequently activating Nrf2/ARE signaling and thereby up-regulating phase II antioxidant enzymes.

Age-related decrease in the mitochondrial sirtuin deacetylase Sirt3 expression associated with ROS accumulation in the auditory cortex of the mimetic aging rat model

Age-related dysfunction of the central auditory system, also known as central presbycusis, can affect speech perception and sound localization. Understanding the pathogenesis of central presbycusis will help to develop novel approaches to prevent or treat this disease. In this study, the mechanisms of central presbycusis were investigated using a mimetic aging rat model induced by chronic injection of D-galactose (D-Gal). We showed that malondialdehyde (MDA) levels were increased and manganese superoxide dismutase (SOD2) activity was reduced in the auditory cortex in natural aging and D-Gal-induced mimetic aging rats. Furthermore, mitochondrial DNA (mtDNA) 4834 bp deletion, abnormal ultrastructure and cell apoptosis in the auditory cortex were also found in natural aging and D-Gal mimetic aging rats. Sirt3, a mitochondrial NAD+-dependent deacetylase, has been shown to play a crucial role in controlling cellular reactive oxygen species (ROS) homeostasis. However, the role of Sirt3 in the pathogenesis of age-related central auditory cortex deterioration is still unclear. Here, we showed that decreased Sirt3 expression might be associated with increased SOD2 acetylation, which negatively regulates SOD2 activity. Oxidative stress accumulation was likely the result of low SOD2 activity and a decline in ROS clearance. Our findings indicate that Sirt3 might play an essential role, via the mediation of SOD2, in central presbycusis and that manipulation of Sirt3 expression might provide a new approach to combat aging and oxidative stress-related diseases.

Preclinical efficacy of melatonin in the amelioration of tenofovir nephrotoxicity by the attenuation of oxidative stress, nitrosative stress, and inflammation in rats

Abstract Background: Nephrotoxicity is a dose-limiting side effect of long-term use of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of human immunodeficiency virus (HIV) infection. Identifying an agent that prevents tenofovir disoproxil fumarate (TDF)-induced renal injury can lead to better tolerance to TDF, and a more effective treatment can be achieved in HIV infected patients. Recent studies show that oxidative stress, nitrosative stress, and inflammation play a role in TDF nephrotoxicity. The present study is aimed at investigating whether melatonin, a potent antioxidant and anti-inflammatory agent, protects against TDF nephrotoxicity in rats. Methods: Adult male rats were used for the study. Some rats received 600 mg/kg body weight TDF by gavage for 35 days, while others received once daily 20 mg/kg body weight melatonin i.p. 2 h before TDF administration. All the rats were sacrificed on the 36th day, after overnight fast. Results: Melatonin pretreatment protected the rats against TDF nephrotoxicity both histologically and biochemically. Biochemically, melatonin pretreatment attenuated TDF-induced renal oxidative stress, nitrosative stress, and inflammation and preserved proximal tubular function. Histologically, melatonin pretreatment prevented TDF-induced proximal tubular injury and mitochondrial injury such as swelling, disruption of cristae, and deposition of amorphous material in the matrix. It restored the lysosomal and mitochondrial numbers in the proximal tubules also. Conclusions: Melatonin pretreatment protects rats from tenofovir-induced damage to proximal tubular mitochondria by attenuating oxidative stress, nitrosative stress, and inflammation. This suggests that it may be useful in ameliorating TDF nephrotoxicity in humans.

Resveratrol up-regulates the erythrocyte plasma membrane redox system and mitigates oxidation-induced alterations in erythrocytes during aging in humans

Reactive oxygen/nitrogen species (ROS/RNS)-mediated oxidative damage followed by disturbed cellular homeostasis is involved in aging and related consequences. Lipid peroxidation, post-translational modifications of proteins, and an impaired defense system due to increased oxidative stress jeopardize cell fate and functions, resulting in cell senescence. Resveratrol, a natural stilbene, has extensively been reported to elicit a plethora of health-promoting effects. The present study carried out on 97 healthy human subjects (62 males and 35 females) of both sexes provides experimental evidence that resveratrol confers ability to up-regulate the plasma membrane redox system (PMRS) along with ascorbate free radical reductase, a compensatory system operating in the cell to maintain cellular redox state. Furthermore, resveratrol provided significant protection against lipid peroxidation and protein carbonylation and restored the cellular redox homeostasis measured in terms of glutathione (GSH) and sulfhydryl (-SH) group levels during oxidation injury in erythrocytes of different age groups in humans. Findings suggest a possible role of resveratrol in retardation of age-dependent oxidative stress.

Clinical perspective on oxidative stress in sporadic amyotrophic lateral sclerosis

Sporadic amyotrophic lateral sclerosis (ALS) is one of the most devastating neurological diseases; most patients die within 3 to 4 years after symptom onset. Oxidative stress is a disturbance in the pro-oxidative/antioxidative balance favoring the pro-oxidative state. Autopsy and laboratory studies in ALS indicate that oxidative stress plays a major role in motor neuron degeneration and astrocyte dysfunction. Oxidative stress biomarkers in cerebrospinal fluid, plasma, and urine are elevated, suggesting that abnormal oxidative stress is generated outside of the central nervous system. Our review indicates that agricultural chemicals, heavy metals, military service, professional sports, excessive physical exertion, chronic head trauma, and certain foods might be modestly associated with ALS risk, with a stronger association between risk and smoking. At the cellular level, these factors are all involved in generating oxidative stress. Experimental studies indicate that a combination of insults that induce modest oxidative stress can exert additive deleterious effects on motor neurons, suggesting that multiple exposures in real-world environments are important. As the disease progresses, nutritional deficiency, cachexia, psychological stress, and impending respiratory failure may further increase oxidative stress. Moreover, accumulating evidence suggests that ALS is possibly a systemic disease. Laboratory, pathologic, and epidemiologic evidence clearly supports the hypothesis that oxidative stress is central in the pathogenic process, particularly in genetically susceptive individuals. If we are to improve ALS treatment, well-designed biochemical and genetic epidemiological studies, combined with a multidisciplinary research approach, are needed and will provide knowledge crucial to our understanding of ALS etiology, pathophysiology, and prognosis.

The redox-associated adaptive response of brain to physical exercise

Reactive oxygen species (ROS) are continuously generated during metabolism. ROS are involved in redox signaling, but in significant concentrations they can greatly elevate oxidative damage leading to neurodegeneration. Because of the enhanced sensitivity of brain to ROS, it is especially important to maintain a normal redox state in brain and spinal cord cell types. The complex effects of exercise benefit brain function, including functional enhancement as well as its preventive and therapeutic roles. Exercise can induce neurogenesis via neurotrophic factors, increase capillarization, decrease oxidative damage, and enhance repair of oxidative damage. Exercise is also effective in attenuating age-associated loss in brain function, which suggests that physical activity-related complex metabolic and redox changes are important for a healthy neural system.

Carotenoid-rich dietary patterns during midlife and subsequent cognitive function

Carotenoids may help to prevent the ageing of the brain. Previous findings regarding β-carotene alone are not consistent. In the present study, we evaluated the cross-time association between a carotenoid-rich dietary pattern (CDP) and subsequent cognitive performance using a sample of 2983 middle-aged adults participating in the SU.VI.MAX (Supplémentation en Vitamines et Minéraux Antioxydants) study. Cognitive performance was assessed in 2007–9 using six neuropsychological tests, and a composite cognitive score was computed. The cognitive data were related to dietary data obtained by repeated 24 h dietary records (1994–6) and to measurements of baseline plasma concentrations of carotenoids (lutein, zeaxanthin, β-cryptoxanthin, lycopene, α-carotene, trans-β-carotene and cis-β-carotene). DP were extracted using the reduced rank regression method for 381 participants and then extrapolated to the whole sample using plasma carotenoid concentrations as response variables. Associations between a CDP and cognitive function measured 13 years later were estimated with ANCOVA providing mean difference values and 95 % CI across the tertiles of CDP. A correlation between CDP and consumption of orange- and green-coloured fruits and vegetables, vegetable oils and soup was observed. CDP was found to be associated with a higher composite cognitive score (mean difference 1·04, 95 % CI 0·20, 1·87, P for trend 0·02), after adjustment for sociodemographic, lifestyle and health factors. Similar findings were obtained for scores obtained in the cued recall task, backward digit span task, trail making test and semantic fluency task (all P for trend < 0·05). Further studies ought to confirm whether a diet providing sufficient quantity and variety of coloured fruits and vegetables may contribute to the preservation of cognitive function during ageing.

Phytoestrogen α-zearalanol ameliorates memory impairment and neuronal DNA oxidation in ovariectomized mice

OBJECTIVE

The aim of this study was to evaluate the effect of a novel phytoestrogen, α-Zearalanol, on Alzheimer's disease-related memory impairment and neuronal oxidation in ovariectomized mice.

METHODS

Female C57/BL6 mice were ovariectomized or received sham operations and treatment with equivalent doses of 17β-estradiol or α-Zearalanol for 8 weeks. Their spatial learning and memory were analyzed using the Morris water maze test. The antioxidant enzyme activities and reactive oxygen species generation, neuronal DNA oxidation, and MutT homolog 1 expression in the hippocampus were measured.

RESULTS

Treatment with 17β-estradiol or α-Zearalanol significantly improved spatial learning and memory performance in ovariectomized mice. In addition, 17β-estradiol and α-Zearalanol attenuated the decrease in antioxidant enzyme activities and increased reactive oxygen species production in ovariectomized mice. The findings indicated a significant elevation in hippocampi neuronal DNA oxidation and reduction in MutT homolog 1 expression in estrogen-deficient mice, but supplementation with 17β-estradiol or α-Zearalanol efficaciously ameliorated this situation.

CONCLUSION

These results demonstrate that α-Zearalanol is potentially beneficial for improving memory impairments and neuronal oxidation damage in a manner similar to that of 17β-estradiol. Therefore, the compound may be a potential therapeutic agent that can ameliorate neurodegenerative disorders related to estrogen deficiency.

Lipid peroxidation triggers neurodegeneration: a redox proteomics view into the Alzheimer disease brain

Lipid peroxidation involves a cascade of reactions in which production of free radicals occurs selectively in the lipid components of cellular membranes. Polyunsaturated fatty acids easily undergo lipid peroxidation chain reactions, which, in turn, lead to the formation of highly reactive electrophilic aldehydes. Among these, the most abundant aldehydes are 4-hydroxy-2-nonenal (HNE) and malondialdehyde, while acrolein is the most reactive. Proteins are susceptible to posttranslational modifications caused by aldehydes binding covalently to specific amino acid residues, in a process called Michael adduction, and these types of protein adducts, if not efficiently removed, may be, and generally are, dangerous for cellular homeostasis. In the present review, we focused the discussion on the selective proteins that are identified, by redox proteomics, as selective targets of HNE modification during the progression and pathogenesis of Alzheimer disease (AD). By comparing results obtained at different stages of the AD, it may be possible to identify key biochemical pathways involved and ideally identify therapeutic targets to prevent, delay, or treat AD.

Aerobic endurance capacity affects spatial memory and SIRT1 is a potent modulator of 8-oxoguanine repair

Regular exercise promotes brain function via a wide range of adaptive responses, including the increased expression of antioxidant and oxidative DNA damage-repairing systems. Accumulation of oxidized DNA base lesions and strand breaks is etiologically linked to for example aging processes and age-associated diseases. Here we tested whether exercise training has an impact on brain function, extent of neurogenesis, and expression of 8-oxoguanine DNA glycosylase-1 (Ogg1) and SIRT1 (silent mating-type information regulation 2 homolog). To do so, we utilized strains of rats with low- and high-running capacity (LCR and HCR) and examined learning and memory, DNA synthesis, expression, and post-translational modification of Ogg1 hippocampal cells. Our results showed that rats with higher aerobic/running capacity had better spatial memory, and expressed less Ogg1, when compared to LCR rats. Furthermore, exercise increased SIRT1 expression and decreased acetylated Ogg1 (AcOgg1) levels, a post-translational modification important for efficient repair of 8-oxo-7,8-dihydroguanine (8-oxoG). Our data on cell cultures revealed that nicotinamide, a SIRT1-specific inhibitor, caused the greatest increase in the acetylation of Ogg1, a finding further supported by our other observations that silencing SIRT1 also markedly increased the levels of AcOgg1. These findings imply that high-running capacity is associated with increased hippocampal function, and SIRT1 level/activity and inversely correlates with AcOgg1 levels and thereby the repair of genomic 8-oxoG.

Depletion of the cellular antioxidant system contributes to tenofovir disoproxil fumarate - induced mitochondrial damage and increased oxido-nitrosative stress in the kidney

BACKGROUND

Nephrotoxicity is a dose limiting side effect of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of HIV infection. The mechanism of tenofovir nephrotoxicity is not clear. Tenofovir is specifically toxic to the proximal convoluted tubules and proximal tubular mitochondria are the targets of tenofovir cytotoxicity. Damaged mitochondria are major sources of reactive oxygen species and cellular damage is reported to occur after the antioxidants are depleted. The purpose of the study is to investigate the alterations in cellular antioxidant system in tenofovir induced renal damage using a rat model.

RESULTS

Chronic tenofovir administration to adult Wistar rats resulted in proximal tubular damage (as evidenced by light microscopy), proximal tubular dysfunction (as shown by Fanconi syndrome and tubular proteinuria), and extensive proximal tubular mitochondrial injury (as revealed by electron microscopy). A 50% increase in protein carbonyl content was observed in the kidneys of TDF treated rats as compared with the control. Reduced glutathione was decreased by 50%. The activity of superoxide dismutase was decreased by 57%, glutathione peroxidase by 45%, and glutathione reductase by 150% as compared with control. Carbonic Anhydrase activity was decreased by 45% in the TDF treated rat kidneys as compared with control. Succinate dehydrogenase activity, an indicator of mitochondrial activity was decreased by 29% in the TDF treated rat kidneys as compared with controls, suggesting mitochondrial dysfunction.

CONCLUSION

Tenofovir- induced mitochondrial damage and increased oxidative stress in the rat kidneys may be due to depletion of the antioxidant system particularly, the glutathione dependent system and MnSOD.

Phenotypic screens targeting neurodegenerative diseases

Neurodegenerative diseases affect millions of people worldwide, and the incidences increase as the population ages. Disease-modifying therapy that prevents or slows disease progression is still lacking, making neurodegenerative diseases an area of high unmet medical need. Target-based drug discovery for disease-modifying agents has been ongoing for many years, without much success due to incomplete understanding of the molecular mechanisms underlying neurodegeneration. Phenotypic screening, starting with a disease-relevant phenotype to screen for compounds that change the outcome of biological pathways rather than activities at certain specific targets, offers an alternative approach to find small molecules or targets that modulate the key characteristics of neurodegeneration. Phenotypic screens that focus on amelioration of disease-specific toxins, protection of neurons from degeneration, or promotion of neuroregeneration could be potential fertile grounds for discovering therapeutic agents for neurodegenerative diseases. In this review, we will summarize the progress of compound screening using these phenotypic-based strategies for this area, with a highlight on unique considerations for disease models, assays, and screening methodologies. We will further provide our perspectives on how best to use phenotypic screening to develop drug leads for neurodegenerative diseases.

Antioxidant status and APOE genotype as susceptibility factors for neurodegeneration in Alzheimer's disease and vascular dementia

Different factors interact to develop neurodegeneration in patients with dementia and other neurodegenerative disorders. Oxidative stress and the ε4 allele of apolipoprotein E (ApoE) are associated with significant alteration in lipid metabolism, in turn connected to a variety of neurodegenerative diseases and aging. Thus, a better understanding of the pathogenetic pathways associated with lipid dyshomeostasis may elucidate the causes of neurodegenerative processes. To address this issue, we evaluated the effects of antioxidant status and APOE genotype on neurodegeneration in patients with dementia of the Alzheimer type (AD), with vascular dementia (VaD), and in elderly healthy controls. Eighty-two AD, 42 VaD patients, and 26 healthy controls were recruited and underwent medial temporal lobe atrophy (MTA) assessment, white matter hyperintensities rating (WMH), serum total antioxidant status assaying (TAS), and APOE genotyping. A logistic regression algorithm applied to our data revealed that a 0.01 mmol/L decrease of TAS concentration increased the probability of MTA by 24% (p=0.038) and that carriers of the APOE ε4 allele showed higher WMH scores (p=0.018), confirming that small variations in antioxidant systems homeostasis are associated with relevant modifications of disease risk. Furthermore, in individuals with analogous TAS values, the presence of the ε4 allele increased the predicted probability of having MTA. These outcomes further sustain the interaction of oxidative stress and APOE genotype to neurodegeneration.

[Is physical activity an elixir?]

Physical exercise has systemic effects, and it can regulate all the organs. The relative maximal aerobic oxygen uptake (VO2max) could have been important in the evolution of humans, since higher VO2max meant better hunting abilities for the Stone Age man. However, it appears that high level of VO2max is also important today, in the 21st century to prevent cardiovascular diseases, cancer and neurodegenerative diseases. High level of VO2max is not just preventive against a wide spectrum of diseases, but it associated with better function of many organs. Relevant data suggest that high level of VO2max is a key factor in prevention of diseases and survival even at the modern civilized world.

Sepiapterin reductase mediates chemical redox cycling in lung epithelial cells

In the lung, chemical redox cycling generates highly toxic reactive oxygen species that can cause alveolar inflammation and damage to the epithelium, as well as fibrosis. In this study, we identified a cytosolic NADPH-dependent redox cycling activity in mouse lung epithelial cells as sepiapterin reductase (SPR), an enzyme important for the biosynthesis of tetrahydrobiopterin. Human SPR was cloned and characterized. In addition to reducing sepiapterin, SPR mediated chemical redox cycling of bipyridinium herbicides and various quinones; this activity was greatest for 1,2-naphthoquinone followed by 9,10-phenanthrenequinone, 1,4-naphthoquinone, menadione, and 2,3-dimethyl-1,4-naphthoquinone. Whereas redox cycling chemicals inhibited sepiapterin reduction, sepiapterin had no effect on redox cycling. Additionally, inhibitors such as dicoumarol, N-acetylserotonin, and indomethacin blocked sepiapterin reduction, with no effect on redox cycling. Non-redox cycling quinones, including benzoquinone and phenylquinone, were competitive inhibitors of sepiapterin reduction but noncompetitive redox cycling inhibitors. Site-directed mutagenesis of the SPR C-terminal substrate-binding site (D257H) completely inhibited sepiapterin reduction but had minimal effects on redox cycling. These data indicate that SPR-mediated reduction of sepiapterin and redox cycling occur by distinct mechanisms. The identification of SPR as a key enzyme mediating chemical redox cycling suggests that it may be important in generating cytotoxic reactive oxygen species in the lung. This activity, together with inhibition of sepiapterin reduction by redox-active chemicals and consequent deficiencies in tetrahydrobiopterin, may contribute to tissue injury.

Dopamine prevents lipid peroxidation-induced accumulation of toxic α-synuclein oligomers by preserving autophagy-lysosomal function

The formation of Lewy bodies containing α-synuclein (α-syn), prominent loss of dopaminergic neurons and dopamine (DA) deficiency in substantia nigra and striatum are histopathological and biochemical hallmarks of Parkinson's disease (PD). Multiple lines of evidence have indicated that a critical pathogenic factor causing PD is enhanced production of reactive oxygen species (ROS), which reacts readily with polyunsaturated fatty acids to cause lipid peroxidation (LPO). LPO products have been shown to facilitate assembly of toxic α-syn oligomers in in vitro studies. Since DA is prone to autoxidation and cause ROS, it has been suggested that interactions among DA, LPO, and α-syn play an important role in neuronal loss in PD. However, the exact mechanism(s) remains unclear. We addressed this issue using a neuronal cell model which inducibly expresses human wild-type α-syn by the tetracycline off (Tet-Off) mechanism and stably expresses high levels of DA transporter. Under retinoic acid elicited neuronal differentiation, cells with or without overexpressing α-syn and with or without exposure to LPO inducer-arachidonic acid (AA), plus 0-500 μM of DA were assessed for the levels of LPO, α-syn accumulation, cell viability, and autophagy. AA exposure elicited similar LPO levels in cells with and without α-syn overexpression, but significantly enhanced the accumulation of α-syn oligomers and monomers only in cultures with Tet-Off induction and decreased cell survival in a LPO-dependent manner. Surprisingly, DA at low concentrations (<50 μM) protected cells from AA cytotoxicity and α-syn accumulation. Such effects were attributed to the ability of DA to preserve autophagic-lysosomal function compromised by the AA exposure. At high concentrations (>100 μM), DA exposure enhanced the toxic effects of AA. To our knowledge, this is the first report showing biphasic effects of DA on neuronal survival and α-syn accumulation.

Abacavir pharmacogenetics--from initial reports to standard of care

Abacavir is a nucleoside analogue reverse transcriptase inhibitor indicated for the treatment of human immunodeficiency virus infection as part of a multidrug, highly active antiretroviral therapy regimen. Despite its efficacy, approximately 5% of individuals who receive abacavir develop an immune-mediated hypersensitivity reaction (HSR) that warrants immediate discontinuation of abacavir and switching to an alternative antiretroviral regimen. Abacavir HSR is associated with individuals who carry the *57:01 variant in the human leukocyte antigen B (HLA-B) gene. There is a large volume of evidence to show that those who carry HLA-B*57:01 are at significantly increased risk of developing HSR and should not receive abacavir. Pharmacogenetic screening to ensure individuals who carry HLA-B*57:01 do not receive abacavir can reduce the incidence of HSR and is now considered the standard of care before prescribing abacavir. Genetic testing to prevent abacavir HSR is currently one of the best examples of integrating pharmacogenetic testing into clinical practice.

Redox-regulating sirtuins in aging, caloric restriction, and exercise

The consequence of decreased nicotinamide adenine dinucleotide (NAD(+)) levels as a result of oxidative challenge is altered activity of sirtuins, which, in turn, brings about a wide range of modifications in mammalian cellular metabolism. Sirtuins, especially SIRT1, deacetylate important transcription factors such as p53, forkhead homeobox type O proteins, nuclear factor κB, or peroxisome proliferator-activated receptor γ coactivator 1α (which controls the transcription of pro- and antioxidant enzymes, by which the cellular redox state is affected). The role of SIRT1 in DNA repair is enigmatic, because it activates Ku70 to cope with double-strand breaks, but deacetylation of apurinic/apyrimidinic endonuclease 1 and probably of 8-oxoguanine-DNA glycosylase 1 decreases the activity of these DNA repair enzymes. The protein-stabilizing effects of the NAD+-dependent lysine deacetylases are readily related to housekeeping and redox regulation. The role of sirtuins in caloric restriction (CR)-related longevity in yeast is currently under debate. However, in mammals, it seems certain that sirtuins are involved in many cellular processes that mediate longevity and disease prevention via the effects of CR through the vascular, neuronal, and muscular systems. Regular physical exercise-mediated health promotion also involves sirtuin-regulated pathways including the antioxidant-, macromolecular damage repair-, energy-, mitochondrial function-, and neuronal plasticity-associated pathways. This review critically evaluates these findings and points out the age-associated role of sirtuins.

Mild oxidative stress induces redistribution of BACE1 in non-apoptotic conditions and promotes the amyloidogenic processing of Alzheimer's disease amyloid precursor protein

BACE1 is responsible for β-secretase cleavage of the amyloid precursor protein (APP), which represents the first step in the production of amyloid β (Aβ) peptides. Previous reports, by us and others, have indicated that the levels of BACE1 protein and activity are increased in the brain cortex of patients with Alzheimer's disease (AD). The association between oxidative stress (OS) and AD has prompted investigations that support the potentiation of BACE1 expression and enzymatic activity by OS. Here, we have established conditions to analyse the effects of mild, non-lethal OS on BACE1 in primary neuronal cultures, independently from apoptotic mechanisms that were shown to impair BACE1 turnover. Six-hour treatment of mouse primary cortical cells with 10-40 µM hydrogen peroxide did not significantly compromise cell viability but it did produce mild oxidative stress (mOS), as shown by the increased levels of reactive radical species and activation of p38 stress kinase. The endogenous levels of BACE1 mRNA and protein were not significantly altered in these conditions, whereas a toxic H2O2 concentration (100 µM) caused an increase in BACE1 protein levels. Notably, mOS conditions resulted in increased levels of the BACE1 C-terminal cleavage product of APP, β-CTF. Subcellular fractionation techniques showed that mOS caused a major rearrangement of BACE1 localization from light to denser fractions, resulting in an increased distribution of BACE1 in fractions containing APP and markers for trans-Golgi network and early endosomes. Collectively, these data demonstrate that mOS does not modify BACE1 expression but alters BACE1 subcellular compartmentalization to favour the amyloidogenic processing of APP, and thus offer new insight in the early molecular events of AD pathogenesis.

Oxygen consumption and usage during physical exercise: the balance between oxidative stress and ROS-dependent adaptive signaling

The complexity of human DNA has been affected by aerobic metabolism, including endurance exercise and oxygen toxicity. Aerobic endurance exercise could play an important role in the evolution of Homo sapiens, and oxygen was not important just for survival, but it was crucial to redox-mediated adaptation. The metabolic challenge during physical exercise results in an elevated generation of reactive oxygen species (ROS) that are important modulators of muscle contraction, antioxidant protection, and oxidative damage repair, which at moderate levels generate physiological responses. Several factors of mitochondrial biogenesis, such as peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), mitogen-activated protein kinase, and SIRT1, are modulated by exercise-associated changes in the redox milieu. PGC-1α activation could result in decreased oxidative challenge, either by upregulation of antioxidant enzymes and/or by an increased number of mitochondria that allows lower levels of respiratory activity for the same degree of ATP generation. Endogenous thiol antioxidants glutathione and thioredoxin are modulated with high oxygen consumption and ROS generation during physical exercise, controlling cellular function through redox-sensitive signaling and protein-protein interactions. Endurance exercise-related angiogenesis, up to a significant degree, is regulated by ROS-mediated activation of hypoxia-inducible factor 1α. Moreover, the exercise-associated ROS production could be important to DNA methylation and post-translation modifications of histone residues, which create heritable adaptive conditions based on epigenetic features of chromosomes. Accumulating data indicate that exercise with moderate intensity has systemic and complex health-promoting effects, which undoubtedly involve regulation of redox homeostasis and signaling.

Metabolic signatures of extreme longevity in northern Italian centenarians reveal a complex remodeling of lipids, amino acids, and gut microbiota metabolism

The aging phenotype in humans has been thoroughly studied but a detailed metabolic profiling capable of shading light on the underpinning biological processes of longevity is still missing. Here using a combined metabonomics approach compromising holistic (1)H-NMR profiling and targeted MS approaches, we report for the first time the metabolic phenotype of longevity in a well characterized human aging cohort compromising mostly female centenarians, elderly, and young individuals. With increasing age, targeted MS profiling of blood serum displayed a marked decrease in tryptophan concentration, while an unique alteration of specific glycerophospholipids and sphingolipids are seen in the longevity phenotype. We hypothesized that the overall lipidome changes specific to longevity putatively reflect centenarians' unique capacity to adapt/respond to the accumulating oxidative and chronic inflammatory conditions characteristic of their extreme aging phenotype. Our data in centenarians support promotion of cellular detoxification mechanisms through specific modulation of the arachidonic acid metabolic cascade as we underpinned increased concentration of 8,9-EpETrE, suggesting enhanced cytochrome P450 (CYP) enzyme activity. Such effective mechanism might result in the activation of an anti-oxidative response, as displayed by decreased circulating levels of 9-HODE and 9-oxoODE, markers of lipid peroxidation and oxidative products of linoleic acid. Lastly, we also revealed that the longevity process deeply affects the structure and composition of the human gut microbiota as shown by the increased extrection of phenylacetylglutamine (PAG) and p-cresol sulfate (PCS) in urine of centenarians. Together, our novel approach in this representative Italian longevity cohort support the hypothesis that a complex remodeling of lipid, amino acid metabolism, and of gut microbiota functionality are key regulatory processes marking exceptional longevity in humans.

Metabolic signatures of extreme longevity in northern Italian centenarians reveal a complex remodeling of lipids, amino acids, and gut microbiota metabolism

The aging phenotype in humans has been thoroughly studied but a detailed metabolic profiling capable of shading light on the underpinning biological processes of longevity is still missing. Here using a combined metabonomics approach compromising holistic ¹H-NMR profiling and targeted MS approaches, we report for the first time the metabolic phenotype of longevity in a well characterized human aging cohort compromising mostly female centenarians, elderly, and young individuals. With increasing age, targeted MS profiling of blood serum displayed a marked decrease in tryptophan concentration, while an unique alteration of specific glycerophospholipids and sphingolipids are seen in the longevity phenotype. We hypothesized that the overall lipidome changes specific to longevity putatively reflect centenarians' unique capacity to adapt/respond to the accumulating oxidative and chronic inflammatory conditions characteristic of their extreme aging phenotype. Our data in centenarians support promotion of cellular detoxification mechanisms through specific modulation of the arachidonic acid metabolic cascade as we underpinned increased concentration of 8,9-EpETrE, suggesting enhanced cytochrome P450 (CYP) enzyme activity. Such effective mechanism might result in the activation of an anti-oxidative response, as displayed by decreased circulating levels of 9-HODE and 9-oxoODE, markers of lipid peroxidation and oxidative products of linoleic acid. Lastly, we also revealed that the longevity process deeply affects the structure and composition of the human gut microbiota as shown by the increased extrection of phenylacetylglutamine (PAG) and p-cresol sulfate (PCS) in urine of centenarians. Together, our novel approach in this representative Italian longevity cohort support the hypothesis that a complex remodeling of lipid, amino acid metabolism, and of gut microbiota functionality are key regulatory processes marking exceptional longevity in humans.

Comparison of the beneficial effect of melatonin on recovery after cut and crush sciatic nerve injury: a combined study using functional, electrophysiological, biochemical, and electron microscopic analyses

PURPOSE

Following tissue injury, melatonin is known to reduce detrimental effects of free radicals by stimulating antioxidant enzymes and also to inhibit posttraumatic polymorphonuclear infiltration. Beneficial effects after peripheral nerve injury have been suggested, but not studied in detail. Therefore, we aimed to elucidate the effects of melatonin on the recovery of the lesioned rat sciatic nerve by means of combined analysis.

METHODS

A total number of 90 rats were randomly distributed into six groups: control (group 1), sham-operated (group 2), sciatic nerve cut (group 3), sciatic nerve cut + melatonin treatment (group 4), sciatic nerve crush (group 5), and sciatic nerve crush + melatonin treatment (group 6). Melatonin was administered intraperitoneally at a dose of 50 mg/kg/day for 6 weeks. Recovery of function was analyzed by assessment of the sciatic functional index based on walking track analysis, somatosensory evoked potentials, biochemical quantification of malondialdehyde, antioxidant enzymes levels, and ultrastructural analysis.

RESULTS

Our data showed the beneficial effect of melatonin on sciatic nerve recovery. Rats treated with melatonin demonstrated better structural preservation of the myelin sheaths compared to the nontreated group. The biochemical analysis confirmed the beneficial effects of melatonin displaying lower lipid peroxidation and higher superoxide dismutase, catalase, and glutathione peroxidase activities in sciatic nerve samples in comparison to nontreated groups.

CONCLUSIONS

The beneficial effects of melatonin administration on the recovery of the cut and crush injured sciatic nerve may be attributed to its antioxidant properties. Based on these investigations, we think that our data would be helpful for clinicians who deal with peripheral nerve injuries.

Oxidative stress, DNA damage, and the telomeric complex as therapeutic targets in acute neurodegeneration

Oxidative stress has been identified as an important contributor to neurodegeneration associated with acute CNS injuries and diseases such as spinal cord injury (SCI), traumatic brain injury (TBI), and ischemic stroke. In this review, we briefly detail the damaging effects of oxidative stress (lipid peroxidation, protein oxidation, etc.) with a particular emphasis on DNA damage. Evidence for DNA damage in acute CNS injuries is presented along with its downstream effects on neuronal viability. In particular, unchecked oxidative DNA damage initiates a series of signaling events (e.g. activation of p53 and PARP-1, cell cycle re-activation) which have been shown to promote neuronal loss following CNS injury. These findings suggest that preventing DNA damage might be an effective way to promote neuronal survival and enhance neurological recovery in these conditions. Finally, we identify the telomere and telomere-associated proteins (e.g. telomerase) as novel therapeutic targets in the treatment of neurodegeneration due to their ability to modulate the neuronal response to both oxidative stress and DNA damage.

Hepatoprotective and antioxidant activity of methanolic extract of flowers of Nerium oleander against CCl4-induced liver injury in rats

OBJECTIVE

To investigate the antioxidant and hepatoprotective activity of methanolic flower extract of Nerium oleander against CCl(4)-induced hepatotoxicity in rats.

METHODS

In vitro antioxidant activity of methanolic extract of flowers of Nerium oleander (MENO-F) was evaluated by various assays, including reducing power, lipid peroxidation, DPPH, ABTS, superoxide anion, hydroxyl radicals and metal chelation. The hepatoprotective and in vivo antioxidant activity of MENO-F were evaluated against CCl(4)-induced hepatic damage in rats. The MENO-F at dose of 100, 200 and 400 mg/kg were administered orally once daily for seven days. Serum enzymatic levels of serum glutamate oxaloacetate transaminase (AST), serum glutamate pyruvate transaminase (ALT), serum alkaline phosphatase (ALP) and total bilirubin were estimated along with estimation of superoxide dismutase (SOD) and malondialdehyde (MDA) levels in liver tissues. Further histopathological examination of the liver sections was carried out to support the induction of hepatotoxicity and hepatoprotective efficacy.

RESULTS

The extract showed potent activities on reducing power, lipid peroxide, DPPH, ABTS, superoxide anion, hydroxyl radical and metal chelation. The substantially elevated serum enzymatic levels of AST, ALT, ALP and total bilirubin were found to be restored towards normalization significantly by the MENO-F in a dose dependent manner with maximum hepatoprotection at 400 mg/kg dose level. The histopathological observations supported the biochemical evidences of hepatoprotection. Elevated level of SOD and decreased level of MDA further strengthen the hepatoprotective observations.

CONCLUSIONS

The results of the present study strongly reveal that MENO-F has potent antioxidant activity and hepatoprotective activity against CCl(4)-induced hepatic damage in experimental animals.

Quercetin protects Saccharomyces cerevisiae against oxidative stress by inducing trehalose biosynthesis and the cell wall integrity pathway

BACKGROUND

Quercetin is a naturally occurring flavonol with antioxidant, anticancer and anti-ageing properties. In this study we aimed to identify genes differentially expressed in yeast cells treated with quercetin and its role in oxidative stress protection.

METHODS

A microarray analysis was performed to characterize changes in the transcriptome and the expression of selected genes was validated by RT-qPCR. Biological processes significantly affected were identified by using the FUNSPEC software and their relevance in H(2)O(2) resistance induced by quercetin was assessed.

RESULTS

Genes associated with RNA metabolism and ribosome biogenesis were down regulated in cells treated with quercetin, whereas genes associated with carbohydrate metabolism, endocytosis and vacuolar proteolysis were up regulated. The induction of genes related to the metabolism of energy reserves, leading to the accumulation of the stress protectant disaccharide trehalose, and the activation of the cell wall integrity pathway play a key role in oxidative stress resistance induced by quercetin.

CONCLUSIONS

These results suggest that quercetin may act as a modulator of cell signaling pathways related to carbohydrate metabolism and cell integrity to exert its protective effects against oxidative stress.