Sporadic Alzheimer disease fibroblasts display an oxidative stress phenotype

Alzheimer's Disease: A Review of Pathology, Current Treatments, and the Potential Therapeutic Effect of Decreasing Oxidative Stress by Combined Vitamin D and l-Cysteine Supplementation

Significance: Excess oxidative stress and neuroinflammation are risk factors in the onset and progression of Alzheimer's disease (AD) and its association with amyloid-β plaque accumulation. Oxidative stress impairs acetylcholine (ACH) and N-methyl-d-aspartate receptor signaling in brain areas that function in memory and learning. Glutathione (GSH) antioxidant depletion positively correlates with the cognitive decline in AD subjects. Treatments that upregulate GSH and ACH levels, which simultaneously decrease oxidative stress and inflammation, may be beneficial for AD. Recent Advances: Some clinical trials have shown a benefit of monotherapy with vitamin D (VD), whose deficiency is linked to AD or with l-cysteine (LC), a precursor of GSH biosynthesis, in reducing mild cognitive impairment. Animal studies have shown a simultaneous decrease in ACH esterase (AChE) and increase in GSH; combined supplementation with VD and LC results in a greater decrease in oxidative stress and inflammation, and increase in GSH levels compared with monotherapy with VD or LC. Therefore, cosupplementation with VD and LC has the potential of increasing GSH, downregulation of oxidative stress, and decreased inflammation and AChE levels. Future Directions: Clinical trials are needed to determine whether safe low-cost dietary supplements, using combined VD+LC, have the potential to alleviate elevated AChE, oxidative stress, and inflammation levels, thereby halting the onset of AD. Goal of Review: The goal of this review is to highlight the pathological hallmarks and current Food and Drug Administration-approved treatments for AD, and discuss the potential therapeutic effect that cosupplementation with VD+LC could manifest by increasing GSH levels in patients. Antioxid. Redox Signal. 40, 663-678.

Selected Biomarkers of Oxidative Stress and Energy Metabolism Disorders in Neurological Diseases

Neurological diseases can be broadly divided according to causal factors into circulatory system disorders leading to ischemic stroke; degeneration of the nerve cells leading to neurodegenerative diseases, such as Alzheimer's (AD) and Parkinson's (PD) diseases, and immune system disorders; bioelectric activity (epileptic) problems; and genetically determined conditions as well as viral and bacterial infections developing inflammation. Regardless of the cause of neurological diseases, they are usually accompanied by disturbances of the central energy in a completely unexplained mechanism. The brain makes up only 2% of the human body's weight; however, while working, it uses as much as 20% of the energy obtained by the body. The energy requirements of the brain are very high, and regulatory mechanisms in the brain operate to ensure adequate neuronal activity. Therefore, an understanding of neuroenergetics is rapidly evolving from a "neurocentric" view to a more integrated picture involving cooperativity between structural and molecular factors in the central nervous system. This article reviewed selected molecular biomarkers of oxidative stress and energy metabolism disorders such as homocysteine, DNA damage such as 8-oxo2dG, genetic variants, and antioxidants such as glutathione in selected neurological diseases including ischemic stroke, AD, PD, and epilepsy. This review summarizes our and others' recent research on oxidative stress in neurological disorders. In the future, the diagnosis and treatment of neurological diseases may be substantially improved by identifying specific early markers of metabolic and energy disorders.

Effect of Chronic Stress Present in Fibroblasts Derived from Patients with a Sporadic Form of AD on Mitochondrial Function and Mitochondrial Turnover

Although the sporadic form of Alzheimer’s disease (AD) is the prevalent form, the cellular events underlying the disease pathogenesis have not been fully characterized. Accumulating evidence points to mitochondrial dysfunction as one of the events responsible for AD progression. We investigated mitochondrial function in fibroblasts collected from patients diagnosed with the sporadic form of AD (sAD), placing a particular focus on mitochondrial turnover. We measured mitochondrial biogenesis and autophagic clearance, and evaluated the presence of bioenergetic stress in sAD cells. The mitochondrial turnover was clearly lower in the fibroblasts from sAD patients than in the fibroblasts from the control subjects, and the levels of many proteins regulating mitochondrial biogenesis, autophagy and mitophagy were decreased in patient cells. Additionally, the sAD fibroblasts had slightly higher mitochondrial superoxide levels and impaired antioxidant defense. Mitochondrial turnover undergoes feedback regulation through mitochondrial retrograde signaling, which is responsible for the maintenance of optimal mitochondrial functioning, and mitochondria-derived ROS participate as signaling molecules in this process. Our results showed that in sAD patients cells, there is a shift in the balance of mitochondrial function, possibly in response to the presence of cellular stress related to disease development.

Inhibition of Retinal Ganglion Cell Loss By a Novel ROCK Inhibitor (E212) in Ischemic Optic Nerve Injury Via Antioxidative and Anti-Inflammatory Actions

Purpose

This study investigated the neuroprotective effects of administration of ROCK inhibitor E212 on ischemic optic neuropathy.

Methods

Rats received an intravitreal injection of either E212 or PBS immediately after optic nerve infarct. The oxidative stress in the retina was detected by performing superoxide dismutase activity and CellROX assays. The integrity of retinal pigment epithelium was determined by staining of zona occludens 1. The visual function, retinal ganglion cell (RGC) density, and RGC apoptosis were determined by using flash visual-evoked potential analysis, retrograde FluoroGold labeling, and TdT-dUTP nick end-labeling assay. Macrophage infiltration was detected by staining for ED1. The protein levels of TNF-α, p-CRMP, p-AKT1, p-STAT3, and CD206 were evaluated using Western blotting.

Results

Administration of E212 resulted in a 1.23-fold increase in the superoxide dismutase activity of the retina and 2.28-fold decrease in RGC-produced reactive oxygen species as compared to the levels observed upon treatment with PBS (P < 0.05). Moreover, E212 prevented the disruption of the blood-retinal barrier (BRB) in contrast to PBS. The P1-N2 amplitude and RGC density in the E212-treated group were 1.75- and 2.05-fold higher, respectively, than those in the PBS-treated group (P < 0.05). The numbers of apoptotic RGCs and macrophages were reduced by 2.93- and 2.54-fold, respectively, in the E212-treated group compared with those in the PBS-treated group (P < 0.05). The levels of p-AKT1, p-STAT3, and CD206 were increased, whereas those of p-PTEN, p-CRMP2, and TNF-α were decreased after treatment with E212 (P < 0.05).

Conclusions

Treatment with E212 suppresses oxidative stress, BRB disruption, and neuroinflammation to protect the visual function in ischemic optic neuropathy.

Mitochondrial Dysfunction: A Common Hallmark Underlying Comorbidity between sIBM and Other Degenerative and Age-Related Diseases

Sporadic inclusion body myositis (sIBM) is an inflammatory myopathy associated, among others, with mitochondrial dysfunction. Similar molecular features are found in Alzheimer's disease (AD) and Type 2 Diabetes Mellitus (T2DM), underlying potential comorbidity. This study aims to evaluate common clinical and molecular hallmarks among sIBM, AD, and T2DM. Comorbidity with AD was assessed in n = 14 sIBM patients by performing neuropsychological and cognitive tests, cranial magnetic resonance imaging, AD cerebrospinal fluid biomarkers (levels of amyloid beta, total tau, and phosphorylated tau at threonine-181), and genetic apolipoprotein E genotyping. In the same sIBM cohort, comorbidity with T2DM was assessed by collecting anthropometric measures and performing an oral glucose tolerance test and insulin determinations. Results were compared to the standard population and other myositis (n = 7 dermatomyositis and n = 7 polymyositis). Mitochondrial contribution into disease was tested by measurement of oxidative/anaerobic and oxidant/antioxidant balances, respiration fluxes, and enzymatic activities in sIBM fibroblasts subjected to different glucose levels. Comorbidity of sIBM with AD was not detected. Clinically, sIBM patients showed signs of misbalanced glucose homeostasis, similar to other myositis. Such misbalance was further confirmed at the molecular level by the metabolic inability of sIBM fibroblasts to adapt to different glucose conditions. Under the standard condition, sIBM fibroblasts showed decreased respiration (0.71 ± 0.08 vs. 1.06 ± 0.04 nmols O2/min; p = 0.024) and increased anaerobic metabolism (5.76 ± 0.52 vs. 3.79 ± 0.35 mM lactate; p = 0.052). Moreover, when glucose conditions were changed, sIBM fibroblasts presented decreased fold change in mitochondrial enzymatic activities (-12.13 ± 21.86 vs. 199.22 ± 62.52 cytochrome c oxidase/citrate synthase ratio; p = 0.017) and increased oxidative stress per mitochondrial activity (203.76 ± 82.77 vs. -69.55 ± 21.00; p = 0.047), underlying scarce metabolic plasticity. These findings do not demonstrate higher prevalence of AD in sIBM patients, but evidences of prediabetogenic conditions were found. Glucose deregulation in myositis suggests the contribution of lifestyle conditions, such as restricted mobility. Additionally, molecular evidences from sIBM fibroblasts confirm that mitochondrial dysfunction may play a role. Monitoring T2DM development and mitochondrial contribution to disease in myositis patients could set a path for novel therapeutic options.

Optimization of extraction for Anemarrhena asphodeloides Bge. using silica gel-based vortex-homogenized matrix solid-phase dispersion and rapid identification of antioxidant substances

A novel and simple method was established for the extraction and determination of seven compounds in Anemarrhena asphodeloides Bge. using silica gel-based vortex-homogenized matrix solid-phase dispersion and ultra-high performance liquid chromatography quadrupole-time of-flight mass spectrometer. The conditions for the extraction were optimized. Silica gel was used as the dispersant, 50% methanol-water was selected as an elution solvent and the grinding time was 3 min. Compared with the traditional ultrasonic-assisted extraction, the developed method was rapid and efficient. In order to screen potential antioxidants, extract dealing with the optimized method was applied to a polyamide chromatography column and a D-101 macroporous resin column. Fr.2.2 showed the highest antioxidant activities with the most content of flavonoid. A total of 25 peaks were identified from the active fraction. A 2,2'-diphenyl-1-picrylhydrazyl ultra-high performance liquid chromatography coupled with mass spectrometry approach was adopted for the rapid and exact screening and identification of antioxidant compounds. It indicated that flavonoids exhibited potential antioxidant activities. The antioxidant activities of nine monomeric compounds in vivo were tested. Structure-activity relationships were discussed. Five flavonoids with the concentration of 500 µg/mL would reduce the oxidative stress of PC12 cells that were induced with 2,2'-azobis[2-methylpropionamidine] dihydrochloride.

Liraglutide Protects Against Brain Amyloid-β1-42 Accumulation in Female Mice with Early Alzheimer's Disease-Like Pathology by Partially Rescuing Oxidative/Nitrosative Stress and Inflammation

Alzheimer’s disease (AD) is the most common form of dementia worldwide, being characterized by the deposition of senile plaques, neurofibrillary tangles (enriched in the amyloid beta (Aβ) peptide and hyperphosphorylated tau (p-tau), respectively) and memory loss. Aging, type 2 diabetes (T2D) and female sex (especially after menopause) are risk factors for AD, but their crosslinking mechanisms remain unclear. Most clinical trials targeting AD neuropathology failed and it remains incurable. However, evidence suggests that effective anti-T2D drugs, such as the GLP-1 mimetic and neuroprotector liraglutide, can be also efficient against AD. Thus, we aimed to study the benefits of a peripheral liraglutide treatment in AD female mice. We used blood and brain cortical lysates from 10-month-old 3xTg-AD female mice, treated for 28 days with liraglutide (0.2 mg/kg, once/day) to evaluate parameters affected in AD (e.g., Aβ and p-tau, motor and cognitive function, glucose metabolism, inflammation and oxidative/nitrosative stress). Despite the limited signs of cognitive changes in mature female mice, liraglutide only reduced their cortical Aβ_1–42 levels. Liraglutide partially attenuated brain estradiol and GLP-1 and activated PKA levels, oxidative/nitrosative stress and inflammation in these AD female mice. Our results support the earlier use of liraglutide as a potential preventive/therapeutic agent against the accumulation of the first neuropathological features of AD in females.

Antioxidant Alternatives in the Treatment of Amyotrophic Lateral Sclerosis: A Comprehensive Review

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that produces a selective loss of the motor neurons of the spinal cord, brain stem and motor cortex. Oxidative stress (OS) associated with mitochondrial dysfunction and the deterioration of the electron transport chain has been shown to be a factor that contributes to neurodegeneration and plays a potential role in the pathogenesis of ALS. The regions of the central nervous system affected have high levels of reactive oxygen species (ROS) and reduced antioxidant defenses. Scientific studies propose treatment with antioxidants to combat the characteristic OS and the regeneration of nicotinamide adenine dinucleotide (NAD+) levels by the use of precursors. This review examines the possible roles of nicotinamide riboside and pterostilbene as therapeutic strategies in ALS.

Human Dermal Fibroblast: A Promising Cellular Model to Study Biological Mechanisms of Major Depression and Antidepressant Drug Response

BACKGROUND

Human dermal fibroblasts (HDF) can be used as a cellular model relatively easily and without genetic engineering. Therefore, HDF represent an interesting tool to study several human diseases including psychiatric disorders. Despite major depressive disorder (MDD) being the second cause of disability in the world, the efficacy of antidepressant drug (AD) treatment is not sufficient and the underlying mechanisms of MDD and the mechanisms of action of AD are poorly understood.

OBJECTIVE

The aim of this review is to highlight the potential of HDF in the study of cellular mechanisms involved in MDD pathophysiology and in the action of AD response.

METHODS

The first part is a systematic review following PRISMA guidelines on the use of HDF in MDD research. The second part reports the mechanisms and molecules both present in HDF and relevant regarding MDD pathophysiology and AD mechanisms of action.

RESULTS

HDFs from MDD patients have been investigated in a relatively small number of works and most of them focused on the adrenergic pathway and metabolism-related gene expression as compared to HDF from healthy controls. The second part listed an important number of papers demonstrating the presence of many molecular processes in HDF, involved in MDD and AD mechanisms of action.

CONCLUSION

The imbalance in the number of papers between the two parts highlights the great and still underused potential of HDF, which stands out as a very promising tool in our understanding of MDD and AD mechanisms of action.

Aldehyde dehydrogenase 2 activity and aldehydic load contribute to neuroinflammation and Alzheimer's disease related pathology

Aldehyde dehydrogenase 2 deficiency (ALDH2*2) causes facial flushing in response to alcohol consumption in approximately 560 million East Asians. Recent meta-analysis demonstrated the potential link between ALDH2*2 mutation and Alzheimer's Disease (AD). Other studies have linked chronic alcohol consumption as a risk factor for AD. In the present study, we show that fibroblasts of an AD patient that also has an ALDH2*2 mutation or overexpression of ALDH2*2 in fibroblasts derived from AD patients harboring ApoE ε4 allele exhibited increased aldehydic load, oxidative stress, and increased mitochondrial dysfunction relative to healthy subjects and exposure to ethanol exacerbated these dysfunctions. In an in vivo model, daily exposure of WT mice to ethanol for 11 weeks resulted in mitochondrial dysfunction, oxidative stress and increased aldehyde levels in their brains and these pathologies were greater in ALDH2*2/*2 (homozygous) mice. Following chronic ethanol exposure, the levels of the AD-associated protein, amyloid-β, and neuroinflammation were higher in the brains of the ALDH2*2/*2 mice relative to WT. Cultured primary cortical neurons of ALDH2*2/*2 mice showed increased sensitivity to ethanol and there was a greater activation of their primary astrocytes relative to the responses of neurons or astrocytes from the WT mice. Importantly, an activator of ALDH2 and ALDH2*2, Alda-1, blunted the ethanol-induced increases in Aβ, and the neuroinflammation in vitro and in vivo. These data indicate that impairment in the metabolism of aldehydes, and specifically ethanol-derived acetaldehyde, is a contributor to AD associated pathology and highlights the likely risk of alcohol consumption in the general population and especially in East Asians that carry ALDH2*2 mutation.

Alzheimer's disease mechanisms in peripheral cells: Promises and challenges

Introduction

Development of efficacious therapeutic interventions for Alzheimer's disease (AD) is hampered by the lack of understanding early disease mechanisms, biomarkers, and models that mimic complex pathophysiology of human disease.

Methods

This article aims to assess to what extent peripheral cells recapitulate molecular mechanisms altered in the brain and could be used as translational models for the development of individualized medicine for AD.

Results

Multiple studies suggest that AD is a systemic disorder with an active crosstalk between brain and periphery where multiple pathways altered in the brain cells are also affected in plasma, cerebrospinal fluid, and other peripheral cells of AD patients.

Discussion

Additional studies to validate molecular mechanisms in peripheral cells using advanced system biology techniques and well-characterized cohorts of AD patients together with the development of standardized protocols should be considered to support the application of peripheral cells in AD research.

Investigation of base excision repair gene variants in late-onset Alzheimer's disease

Base excision repair (BER) defects and concomitant oxidative DNA damage accumulation play a role in the etiology and progression of late-onset Alzheimer’s disease (LOAD). However, it is not known whether genetic variant(s) of specific BER genes contribute to reduced BER activity in LOAD patients and whether they are associated with risk, development and/or progression of LOAD. Therefore, we performed targeted next generation sequencing for three BER genes, uracil glycosylase (UNG), endonuclease VIII-like DNA glycosylase 1 (NEIL1) and polymerase β (POLβ) including promoter, exonic and intronic regions in peripheral blood samples and postmortem brain tissues (temporal cortex, TC and cerebellum, CE) from LOAD patients, high-pathology control and cognitively normal age-matched controls. In addition, the known LOAD risk factor, APOE was included in this study to test whether any BER gene variants associate with APOE variants, particularly APOE ε4. We show that UNG carry five significant variants (rs1610925, rs2268406, rs80001089, rs1018782 and rs1018783) in blood samples of Turkish LOAD patients compared to age-matched controls and one of them (UNG rs80001089) is also significant in TC from Brazilian LOAD patients (p<0.05). The significant variants present only in CE and TC from LOAD are UNG rs2569987 and POLβ rs1012381950, respectively. There is also significant epistatic relationship (p = 0.0410) between UNG rs80001089 and NEIL1 rs7182283 in TC from LOAD subjects. Our results suggest that significant BER gene variants may be associated with the risk of LOAD in non-APOE ε4 carriers. On the other hand, there are no significant UNG, NEIL1 and POLβ variants that could affect their protein level and function, suggesting that there may be other factors such as post-transcriptional or–translational modifications responsible for the reduced activities and protein levels of these genes in LOAD pathogenesis. Further studies with increased sample size are needed to confirm the relationship between BER variants and LOAD risk.

Age- and Nicotine-Associated Gene Expression Changes in the Hippocampus of APP/PS1 Mice

The etiology of Alzheimer's disease (AD) has been intensively studied. However, little is known about the molecular alterations in early-stage and late-stage AD. Hence, we performed RNA sequencing and assessed differentially expressed genes (DEGs) in the hippocampus of 18-month and 7-month-old APP/PS1 mice. Moreover, the DEGs induced by treatment with nicotine, the nicotinic acetylcholine receptor agonist that is known to improve cognition in AD, were also analyzed in old and young APP/PS1 mice. When comparing old APP/PS1 mice with their younger littermates, we found an upregulation in genes associated with calcium overload, immune response, cancer, and synaptic function; the transcripts of 14 calcium ion channel subtypes were significantly increased in aged mice. In contrast, the downregulated genes in aged mice were associated with ribosomal components, mitochondrial respiratory chain complex, and metabolism. Through comparison with DEGs in normal aging from previous reports, we found that changes in calcium channel genes remained one of the prominent features in aged APP/PS1 mice. Nicotine treatment also induced changes in gene expression. Indeed, nicotine augmented glycerolipid metabolism, but inhibited PI3K and MAPK signaling in young mice. In contrast, nicotine affected genes associated with cell senescence and death in old mice. Our study suggests a potential network connection between calcium overload and cellular signaling, in which additional nicotinic activation might not be beneficial in late-stage AD.

Overactive BRCA1 Affects Presenilin 1 in Induced Pluripotent Stem Cell-Derived Neurons in Alzheimer's Disease

The BRCA1 protein, one of the major players responsible for DNA damage response has recently been linked to Alzheimer's disease (AD). Using primary fibroblasts and neurons reprogrammed from induced pluripotent stem cells (iPSC) derived from familial AD (FAD) patients, we studied the role of the BRCA1 protein underlying molecular neurodegeneration. By whole-transcriptome approach, we have found wide range of disturbances in cell cycle and DNA damage response in FAD fibroblasts. This was manifested by significantly increased content of BRCA1 phosphorylated on Ser1524 and abnormal ubiquitination and subcellular distribution of presenilin 1 (PS1). Accordingly, the iPSC-derived FAD neurons showed increased content of BRCA1(Ser1524) colocalized with degraded PS1, accompanied by an enhanced immunostaining pattern of amyloid-β. Finally, overactivation of BRCA1 was followed by an increased content of Cdc25C phosphorylated on Ser216, likely triggering cell cycle re-entry in FAD neurons. This study suggests that overactivated BRCA1 could both influence PS1 turnover leading to amyloid-β pathology and promote cell cycle re-entry-driven cell death of postmitotic neurons in AD.

Enhanced mitochondrial DNA repair of the common disease-associated variant, Ser326Cys, of hOGG1 through small molecule intervention

The common oxidatively generated lesion, 8-oxo-7,8-dihydroguanine (8-oxoGua), is removed from DNA by base excision repair. The glycosylase primarily charged with recognition and removal of this lesion is 8-oxoGuaDNA glycosylase 1 (OGG1). When left unrepaired, 8-oxodG alters transcription and is mutagenic. Individuals homozygous for the less active OGG1 allele, Ser326Cys, have increased risk of several cancers. Here, small molecule enhancers of OGG1 were identified and tested for their ability to stimulate DNA repair and protect cells from the environmental hazard paraquat (PQ). PQ-induced mtDNA damage was inversely proportional to the levels of OGG1 expression whereas stimulation of OGG1, in some cases, entirely abolished its cellular effects. The PQ-mediated decline of mitochondrial membrane potential or nuclear condensation were prevented by the OGG1 activators. In addition, in Ogg1-/- mouse embryonic fibroblasts complemented with hOGG1S326C, there was increased cellular and mitochondrial reactive oxygen species compared to their wild type counterparts. Mitochondrial extracts from cells expressing hOGG1S326C were deficient in mitochondrial 8-oxodG incision activity, which was rescued by the OGG1 activators. These data demonstrate that small molecules can stimulate OGG1 activity with consequent cellular protection. Thus, OGG1-activating compounds may be useful in select humans to mitigate the deleterious effects of environmental oxidants and mutagens.

Plasma lipid peroxidation biomarkers for early and non-invasive Alzheimer Disease detection

INTRODUCTION

Alzheimer Disease (AD) standard diagnosis is based on evaluations and biomarkers that are non-specific, expensive, or requires invasive sampling. Therefore, an early, and non-invasive diagnosis is required. As regards molecular mechanisms, recent research has shown that lipid peroxidation plays an important role.

METHODS

Well-defined participants groups were recruited. Lipid peroxidation compounds were determined in plasma using a validated analytical method. Statistical studies consisted of an elastic-net-penalized logistic regression adjustment.

RESULTS

The regression model fitted to the data included six variables (lipid peroxidation biomarkers) as potential predictors of early AD. This model achieved an apparent area under the receiver operating characteristics (AUC-ROCs) of 0.883 and a bootstrap-validated AUC-ROC of 0.817. Calibration of the model showed very low deviations from real probabilities.

CONCLUSION

A satisfactory early diagnostic model has been obtained from plasma levels of 6 lipid peroxidation compounds, indicating the individual probability of suffering from early AD.

Mitochondrial abnormalities in Parkinson's disease and Alzheimer's disease: can mitochondria be targeted therapeutically?

Mitochondrial abnormalities have been identified as a central mechanism in multiple neurodegenerative diseases and, therefore, the mitochondria have been explored as a therapeutic target. This review will focus on the evidence for mitochondrial abnormalities in the two most common neurodegenerative diseases, Parkinson's disease and Alzheimer's disease. In addition, we discuss the main strategies which have been explored in these diseases to target the mitochondria for therapeutic purposes, focusing on mitochondrially targeted antioxidants, peptides, modulators of mitochondrial dynamics and phenotypic screening outcomes.

NAD+ supplementation normalizes key Alzheimer's features and DNA damage responses in a new AD mouse model with introduced DNA repair deficiency

Emerging findings suggest that compromised cellular bioenergetics and DNA repair contribute to the pathogenesis of Alzheimer's disease (AD), but their role in disease-defining pathology is unclear. We developed a DNA repair-deficient 3xTgAD/Polβ+/- mouse that exacerbates major features of human AD including phosphorylated Tau (pTau) pathologies, synaptic dysfunction, neuronal death, and cognitive impairment. Here we report that 3xTgAD/Polβ+/- mice have a reduced cerebral NAD+/NADH ratio indicating impaired cerebral energy metabolism, which is normalized by nicotinamide riboside (NR) treatment. NR lessened pTau pathology in both 3xTgAD and 3xTgAD/Polβ+/- mice but had no impact on amyloid β peptide (Aβ) accumulation. NR-treated 3xTgAD/Polβ+/- mice exhibited reduced DNA damage, neuroinflammation, and apoptosis of hippocampal neurons and increased activity of SIRT3 in the brain. NR improved cognitive function in multiple behavioral tests and restored hippocampal synaptic plasticity in 3xTgAD mice and 3xTgAD/Polβ+/- mice. In general, the deficits between genotypes and the benefits of NR were greater in 3xTgAD/Polβ+/- mice than in 3xTgAD mice. Our findings suggest a pivotal role for cellular NAD+ depletion upstream of neuroinflammation, pTau, DNA damage, synaptic dysfunction, and neuronal degeneration in AD. Interventions that bolster neuronal NAD+ levels therefore have therapeutic potential for AD.

Linking deregulation of non-coding RNA to the core pathophysiology of Alzheimer's disease: An integrative review

The human genome encodes a vast repertoire of protein non-coding RNAs (ncRNA), some specific to the brain. MicroRNAs, which interfere with the translation of target mRNAs, are of particular interest since their deregulation has been implicated in neurodegenerative disorders like Alzheimer's disease (AD). However, it remains challenging to link the complex body of observations on miRNAs and AD into a coherent framework. Using extensive graphical support, this article discusses how a diverse panoply of miRNAs convergently and divergently impact (and are impacted by) core pathophysiological processes underlying AD: neuroinflammation and oxidative stress; aberrant generation of β-amyloid-42 (Aβ42); anomalies in the production, cleavage and post-translational marking of Tau; impaired clearance of Aβ42 and Tau; perturbation of axonal organisation; disruption of synaptic plasticity; endoplasmic reticulum stress and the unfolded protein response; mitochondrial dysfunction; aberrant induction of cell cycle re-entry; and apoptotic loss of neurons. Intriguingly, some classes of miRNA provoke these cellular anomalies, whereas others act in a counter-regulatory, protective mode. Moreover, changes in levels of certain species of miRNA are a consequence of the above-mentioned anomalies. In addition to miRNAs, circular RNAs, piRNAs, long non-coding RNAs and other types of ncRNA are being increasingly implicated in AD. Overall, a complex mesh of deregulated and multi-tasking ncRNAs reciprocally interacts with core pathophysiological mechanisms underlying AD. Alterations in ncRNAs can be detected in CSF and the circulation as well as the brain and are showing promise as biomarkers, with the ultimate goal clinical exploitation as targets for novel modes of symptomatic and course-altering therapy.

Defective mitochondrial respiration, altered dNTP pools and reduced AP endonuclease 1 activity in peripheral blood mononuclear cells of Alzheimer's disease patients

AIMS

Accurate biomarkers for early diagnosis of Alzheimer's disease (AD) are badly needed. Recent reports suggest that dysfunctional mitochondria and DNA damage are associated with AD development. In this report, we measured various cellular parameters, related to mitochondrial bioenergetics and DNA damage, in peripheral blood mononuclear cells (PBMCs) of AD and control participants, for biomarker discovery.

METHODS

PBMCs were isolated from 53 patients with AD of mild to moderate degree and 30 age-matched healthy controls. Tests were performed on the PBMCs from as many of these participants as possible. We measured glycolysis and mitochondrial respiration fluxes using the Seahorse Bioscience flux analyzer, mitochondrial ROS production using flow cytometry, dNTP levels by way of a DNA polymerization assay, DNA strand breaks using the Fluorometric detection of Alkaline DNA Unwinding (FADU) assay, and APE1 incision activity (in cell lysates) on a DNA substrate containing an AP site (to estimate DNA repair efficiency).

RESULTS

In the PBMCs of AD patients, we found reduced basal mitochondrial oxygen consumption, reduced proton leak, higher dATP level, and lower AP endonuclease 1 activity, depending on adjustments for gender and/or age.

CONCLUSIONS

This study reveals impaired mitochondrial respiration, altered dNTP pools and reduced DNA repair activity in PBMCs of AD patients, thus suggesting that these biochemical activities may be useful as biomarkers for AD.

Protective effects of NSP-116, a novel imidazolyl aniline derivative, against light-induced retinal damage in vitro and in vivo

In this study, we investigated the protective effects of NSP-116 [4-(4-acetylpiperazin-1-yl)-2-(1H-imidazol-1-yl) aniline], a novel imidazolyl aniline derivative, against light-induced photoreceptor cell damage. In an in vitro experiment, murine photoreceptor (661W) cells were damaged by exposure to light for 24h. Viability of 661W cells after light exposure was assessed by Hoechst 33342/Propidium iodide nuclear staining and a tetrazolium salt (WST-8) assay. Intracellular radical production in 661W cells was evaluated using the reactive oxygen species (ROS) sensitive probe 5-(and 6)-chloromethyl-2, 7-dichlorodihydrofluorescein diacetate acetyl ester (CM-H2DCFDA). NSP-116 significantly suppressed light-induced cell death and ROS production in 661W cells. In an in vivo mouse experiment, retinal damage was induced by exposure to white light at 8000lx for 3h after dark adaptation. Retinal damage was evaluated by recording the electroretinogram and measuring the outer nuclear layer (ONL) thickness at 5 days after light exposure. Single oral administration of NSP-116 before light exposure protected retinal function and ONL thinning after light exposure. Furthermore, the effect of NSP-116 on lipid peroxidation was evaluated using thiobarbituric acid reactive substance (TBARS) assay in porcine retina, and was found to decrease the production of TBARS. Electron spin resonance (ESR) measurements showed that NSP-116 exhibited radical scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, superoxide anion radical (∙O2(-)), and hydroxyl radical (∙OH). These findings suggest that NSP-116 has protective effects against light-induced photoreceptor degeneration in vitro and in vivo as a free radical scavenger, and it may be a novel therapeutic agent for retinal degenerative disorders, such as dry age-related macular degeneration (AMD).

Gene-specific mitochondria dysfunctions in human TARDBP and C9ORF72 fibroblasts

Dysregulation of RNA metabolism represents an important pathogenetic mechanism in both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) due to the involvement of the DNA/RNA-binding proteins TDP-43 and FUS and, more recently, of C9ORF72. A potential link between dysregulation of RNA metabolism and mitochondrial dysfunction is recently emerged in TDP-43 disease models. To further investigate the possible relationship between these two pathogenetic mechanisms in ALS/FTD, we studied mitochondria functionality in human mutant TARDBP(p.A382T) and C9ORF72 fibroblasts grown in galactose medium to induce a switch from a glycolytic to an oxidative metabolism. In this condition we observed significant changes in mitochondria morphology and ultrastructure in both mutant cells with a fragmented mitochondria network particularly evident in TARDBP(p.A382T) fibroblasts. From analysis of the mitochondrial functionality, a decrease of mitochondria membrane potential with no alterations in oxygen consumption rate emerged in TARDBP fibroblasts. Conversely, an increased oxygen consumption and mitochondria hyperpolarization were observed in C9ORF72 fibroblasts in association to increased ROS and ATP content. We found evidence of autophagy/mitophagy in dynamic equilibrium with the biogenesis of novel mitochondria, particularly in mutant C9ORF72 fibroblasts where an increase of mitochondrial DNA content and mass, and of PGC1-α protein was observed. Our imaging and biochemical data show that wild-type and mutant TDP-43 proteins do not localize at mitochondria so that the molecular mechanisms responsible for such mitochondria impairment remain to be further elucidated. For the first time our findings assess a link between C9ORF72 and mitochondria dysfunction and indicate that mitochondria functionality is affected in TARDBP and C9ORF72 fibroblasts with gene-specific features in oxidative conditions. As in neuronal metabolism mitochondria are actively used for ATP production, we speculate that TARDBP and C9ORF72 mutations might trigger cell death by impairing not only RNA metabolism, but also mitochondria activity in ALS/FTD neurons.

Nutrients, Microglia Aging, and Brain Aging

As the life expectancy continues to increase, the cognitive decline associated with Alzheimer's disease (AD) becomes a big major issue in the world. After cellular activation upon systemic inflammation, microglia, the resident immune cells in the brain, start to release proinflammatory mediators to trigger neuroinflammation. We have found that chronic systemic inflammatory challenges induce differential age-dependent microglial responses, which are in line with the impairment of learning and memory, even in middle-aged animals. We thus raise the concept of “microglia aging.” This concept is based on the fact that microglia are the key contributor to the acceleration of cognitive decline, which is the major sign of brain aging. On the other hand, inflammation induces oxidative stress and DNA damage, which leads to the overproduction of reactive oxygen species by the numerous types of cells, including macrophages and microglia. Oxidative stress-damaged cells successively produce larger amounts of inflammatory mediators to promote microglia aging. Nutrients are necessary for maintaining general health, including the health of brain. The intake of antioxidant nutrients reduces both systemic inflammation and neuroinflammation and thus reduces cognitive decline during aging. We herein review our microglia aging concept and discuss systemic inflammation and microglia aging. We propose that a nutritional approach to controlling microglia aging will open a new window for healthy brain aging.

The Response to Oxidative DNA Damage in Neurons: Mechanisms and Disease

There is a growing body of evidence indicating that the mechanisms that control genome stability are of key importance in the development and function of the nervous system. The major threat for neurons is oxidative DNA damage, which is repaired by the base excision repair (BER) pathway. Functional mutations of enzymes that are involved in the processing of single-strand breaks (SSB) that are generated during BER have been causally associated with syndromes that present important neurological alterations and cognitive decline. In this review, the plasticity of BER during neurogenesis and the importance of an efficient BER for correct brain function will be specifically addressed paying particular attention to the brain region and neuron-selectivity in SSB repair-associated neurological syndromes and age-related neurodegenerative diseases.

Epigenetic Research of Neurodegenerative Disorders Using Patient iPSC-Based Models

Epigenetic mechanisms play a role in human disease but their involvement in pathologies from the central nervous system has been hampered by the complexity of the brain together with its unique cellular architecture and diversity. Until recently, disease targeted neural types were only available as postmortem materials after many years of disease evolution. Current in vitro systems of induced pluripotent stem cells (iPSCs) generated by cell reprogramming of somatic cells from patients have provided valuable disease models recapitulating key pathological molecular events. Yet whether cell reprogramming on itself implies a truly epigenetic reprogramming, the epigenetic mechanisms governing this process are only partially understood. Moreover, elucidating epigenetic regulation using patient-specific iPSC-derived neural models is expected to have a great impact to unravel the pathophysiology of neurodegenerative diseases and to hopefully expand future therapeutic possibilities. Here we will critically review current knowledge of epigenetic involvement in neurodegenerative disorders focusing on the potential of iPSCs as a promising tool for epigenetic research of these diseases.

DNA Damage, DNA Repair, Aging, and Neurodegeneration

Aging in mammals is accompanied by a progressive atrophy of tissues and organs, and stochastic damage accumulation to the macromolecules DNA, RNA, proteins, and lipids. The sequence of the human genome represents our genetic blueprint, and accumulating evidence suggests that loss of genomic maintenance may causally contribute to aging. Distinct evidence for a role of imperfect DNA repair in aging is that several premature aging syndromes have underlying genetic DNA repair defects. Accumulation of DNA damage may be particularly prevalent in the central nervous system owing to the low DNA repair capacity in postmitotic brain tissue. It is generally believed that the cumulative effects of the deleterious changes that occur in aging, mostly after the reproductive phase, contribute to species-specific rates of aging. In addition to nuclear DNA damage contributions to aging, there is also abundant evidence for a causative link between mitochondrial DNA damage and the major phenotypes associated with aging. Understanding the mechanistic basis for the association of DNA damage and DNA repair with aging and age-related diseases, such as neurodegeneration, would give insight into contravening age-related diseases and promoting a healthy life span.

Herbs to curb cyclic nucleotide phosphodiesterase and their potential role in Alzheimer's disease

Cyclic nucleotides viz., cAMP/cGMP has been well known to play important role in cellular function and deficiency in their levels has been implicated in the pathogenesis of various neurodegenerative disorders including Alzheimer's disease (AD). Phosphodiesterases (PDE) are the enzymes involved in the metabolism of cyclic nucleotides and the inhibition of phosphodiesterases is considered to be viable strategy to restore the level of cyclic nucleotides and their functions in the brain. Various synthetic PDE inhibitors had been used clinically for various disorders and also suggested to be useful candidates for treating neurological disorders. However, side effects of these synthetic PDE inhibitors have limited their use in clinical practice. Natural plant extracts or their bio-active compounds are considered to be safe and are widely acceptable. During the last decade, many plant extracts or their bio-active compounds were tested pre-clinically for PDE inhibitory activity and are reported to be equally potent in inhibiting PDE's, as that of synthetic compounds. The present review is aimed to discuss the potential plant extract/compounds with PDE inhibitory activity and critically discuss their potential role in Alzheimer's disease.

DNA damage in neurodegenerative diseases

Following the observation of increased oxidative DNA damage in nuclear and mitochondrial DNA extracted from post-mortem brain regions of patients affected by neurodegenerative diseases, the last years of the previous century and the first decade of the present one have been largely dedicated to the search of markers of DNA damage in neuronal samples and peripheral tissues of patients in early, intermediate or late stages of neurodegeneration. Those studies allowed to demonstrate that oxidative DNA damage is one of the earliest detectable events in neurodegeneration, but also revealed cytogenetic damage in neurodegenerative conditions, such as for example a tendency towards chromosome 21 malsegregation in Alzheimer's disease. As it happens for many neurodegenerative risk factors the question of whether DNA damage is cause or consequence of the neurodegenerative process is still open, and probably both is true. The research interest in markers of oxidative stress was shifted, in recent years, towards the search of epigenetic biomarkers of neurodegenerative disorders, following the accumulating evidence of a substantial contribution of epigenetic mechanisms to learning, memory processes, behavioural disorders and neurodegeneration. Increasing evidence is however linking DNA damage and repair with epigenetic phenomena, thereby opening the way to a very attractive and timely research topic in neurodegenerative diseases. We will address those issues in the context of Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis, which represent three of the most common neurodegenerative pathologies in humans.

The role of DNA base excision repair in brain homeostasis and disease

Chemical modification and spontaneous loss of nucleotide bases from DNA are estimated to occur at the rate of thousands per human cell per day. DNA base excision repair (BER) is a critical mechanism for repairing such lesions in nuclear and mitochondrial DNA. Defective expression or function of proteins required for BER or proteins that regulate BER have been consistently associated with neurological dysfunction and disease in humans. Recent studies suggest that DNA lesions in the nuclear and mitochondrial compartments and the cellular response to those lesions have a profound effect on cellular energy homeostasis, mitochondrial function and cellular bioenergetics, with especially strong influence on neurological function. Further studies in this area could lead to novel approaches to prevent and treat human neurodegenerative disease.

The impact of base excision DNA repair in age-related neurodegenerative diseases

The aging process and several age-related neurodegenerative disorders have been linked to elevated levels of DNA damage induced by ROS and deficiency in DNA repair mechanisms. DNA damage induced by ROS is a byproduct of cellular respiration and accumulation of damage over time, is a fundamental aspect of a main theory of aging. Mitochondria have a pivotal role in generating cellular oxidative stress, and mitochondrial dysfunction has been associated with several diseases. DNA base excision repair is considered the major pathway for repair of oxidized bases in DNA both in the nuclei and in mitochondria, and in neurons this mechanism is particularly important because non-diving cells have limited back-up DNA repair mechanisms. An association between elevated oxidative stress and a decrease in BER is strongly related to the aging process and has special relevance in age-related neurodegenerative diseases. Here, we review the role of DNA repair in aging, focusing on the implications of the DNA base excision repair pathways and how alterations in expression of these DNA repair proteins are related to the aging process and to age-related neurodegenerative diseases.

DNA polymerase β deficiency leads to neurodegeneration and exacerbates Alzheimer disease phenotypes

We explore the role of DNA damage processing in the progression of cognitive decline by creating a new mouse model. The new model is a cross of a common Alzheimer's disease (AD) mouse (3xTgAD), with a mouse that is heterozygous for the critical DNA base excision repair enzyme, DNA polymerase β. A reduction of this enzyme causes neurodegeneration and aggravates the AD features of the 3xTgAD mouse, inducing neuronal dysfunction, cell death and impairing memory and synaptic plasticity. Transcriptional profiling revealed remarkable similarities in gene expression alterations in brain tissue of human AD patients and 3xTg/Polβ(+/-) mice including abnormalities suggestive of impaired cellular bioenergetics. Our findings demonstrate that a modest decrement in base excision repair capacity can render the brain more vulnerable to AD-related molecular and cellular alterations.

Site-2 protease responds to oxidative stress and regulates oxidative injury in mammalian cells

Site-2 protease (S2P) is a membrane-embedded protease that site-specifically cleaves intramembrane transcription factors, a necessary step for their maturation. S2P is well known to regulate cholesterol biosynthesis and endoplasmic reticulum stress in mammalian cells. In this study, we hypothesized that S2P could be responsible for the regulation of cellular oxidative injury under oxidative stress. Wild type Chinese hamster ovary (WT CHO) cells and their mutant M19 cells with defective S2P gene were exposed to different oxidative stress conditions. Results showed that oxidative stress significantly up-regulated S2P expression in WT CHO cells. Notably, M19 cells had remarkably higher level of superoxide and elevated rates of cell death than WT CHO cells. The vulnerability to oxidative stress was reversed by the transfection of S2P gene but not rescued by exogenous supplement of cholesterol, oleate, and mevalonate, indicating that lack of S2P gene leads cells to be more vulnerable to oxidative stress. Furthermore, compared with WT CHO cells, M19 cells had higher nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity and lower paraoxonase-2 expression. Taken together, these results suggest that S2P can be a protease responding to oxidative stress and has the function of regulating cellular oxidative injury.

Protective effect of ((4-tert-butylcyclohexylidene) methyl) (4-methoxystyryl) sulfide, a novel unsymmetrical divinyl sulfide, on an oxidative stress model induced by sodium nitroprusside in mouse brain: involvement of glutathione peroxidase activity

OBJECTIVES

In this study, the antioxidant action of ((4-tert-butylcyclohexylidene) methyl) (4-methoxystyryl) sulfide, a novel unsymmetrical divinyl sulfide, against oxidative damage induced by sodium nitroprusside (SNP) in brains of mice was investigated.

METHODS

Mice received SNP (0.335 μmol/site, intracerebroventricular) 30 min after administration of sulfide (10 mg/kg, intragastrically). After 1 h, animals were sacrificed and the brains were removed to biochemistry analysis. Thiobarbituric acid reactive species (TBARS), protein carbonyl (PC) and non-protein thiol (NPSH) levels, as well as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) activities were determined.

KEY FINDINGS

SNP increased TBARS and PC levels, CAT, GPx, GR and GST activities and reduced NPSH levels. Administration of the sulfide attenuated the changes produced by SNP and increased per se GPx activity in brains of mice. Toxicological parameters revealed that this compound did not cause acute renal or hepatic damage.

CONCLUSIONS

In conclusion, ((4-tert-butylcyclohexylidene) methyl) (4-methoxystyryl) sulfide protected against oxidative damage caused by SNP in mouse brain. GPx activity is involved, at least in part, in the cerebral antioxidant action of this compound.

The role of calpain in an in vivo model of oxidative stress-induced retinal ganglion cell damage

PURPOSE

In this study, we set out to establish an in vivo animal model of oxidative stress in the retinal ganglion cells (RGCs) and determine whether there is a link between oxidative stress in the RGCs and the activation of calpain, a major part of the apoptotic pathway.

MATERIALS AND METHODS

Oxidative stress was induced in the RGCs of C57BL/6 mice by the intravitreal administration of 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH, 30mM, 2μl). Control eyes were injected with 2μl of vehicle. Surviving Fluorogold (FG)-labeled RGCs were then counted in retinal flat mounts. Double staining with CellROX and Annexin V was performed to investigate the co-localization of free radical generation and apoptosis. An immunoblot assay was used both to indirectly evaluate calpain activation in the AAPH-treated eyes by confirming α-fodrin cleavage, and also to evaluate the effect of SNJ-1945 (a specific calpain inhibitor: 4% w/v, 100mg/kg, intraperitoneal administration) in these eyes.

RESULTS

Intravitreal administration of AAPH led to a significant decrease in FG-labeled RGCs 7days after treatment (control: 3806.7±575.2RGCs/mm(2), AAPH: 3156.1±371.2RGCs/mm(2), P<0.01). CellROX and Annexin V signals were co-localized in the FG-labeled RGCs 24h after AAPH injection. An immunoblot assay revealed a cleaved α-fodrin band that increased significantly 24h after AAPH administration. Intraperitoneally administered SNJ-1945 prevented the cleavage of α-fodrin and had a neuroprotective effect against AAPH-induced RGC death (AAPH: 3354.0±226.9RGCs/mm(2), AAPH+SNJ-1945: 3717.1±614.6RGCs/mm(2), P<0.01).

CONCLUSION

AAPH administration was an effective model of oxidative stress in the RGCs, showing that oxidative stress directly activated the calpain pathway and induced RGC death. Furthermore, inhibition of the calpain pathway protected the RGCs after AAPH administration.

Superoxide dismutase 1 mutation in a cellular model of amyotrophic lateral sclerosis shifts energy generation from oxidative phosphorylation to glycolysis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder involving the progressive degeneration of motor neurons in the brain and spinal cord. Mitochondrial dysfunction plays a key role in ALS disease progression and has been observed in several ALS cellular and animal models. Here, we show that fibroblasts isolated from ALS cases with a Cu/Zn superoxide dismutase (SOD1) I113T mutation recapitulate these mitochondrial defects. Using a novel technique, which measures mitochondrial respiration and glycolytic flux simultaneously in living cells, we have shown that SOD1 mutation causes a reduction in mitochondrial respiration and an increase in glycolytic flux. This causes a reduction in adenosine triphosphate produced by oxidative phosphorylation and an increase in adenosine triphosphate produced by glycolysis. Switching the energy source from glucose to galactose caused uncoupling of mitochondria with increased proton leak in SOD1(I113T) fibroblasts. Assessment of the contribution of fatty acid oxidation to total respiration, suggested that fatty acid oxidation is reduced in SOD1 ALS fibroblasts, an effect which can be mimicked by starving the control cells of glucose. These results highlight the importance of understanding the interplay between the major metabolic pathways, which has the potential to lead to strategies to correct the metabolic dysregulation observed in ALS cases.

Calorie restriction and resveratrol supplementation prevent age-related DNA and RNA oxidative damage in a non-human primate

Oxidative stress is a key factor in the aging process and in the development of age-related diseases. Because nutritional interventions such as caloric restriction (CR) delay the onset of age-related diseases and increase the lifespan of many species, the impact of a moderate CR was tested on male grey mouse lemur (Microcebus murinus), which have a median survival time of 5.7 years in captivity. The effects of CR on these lemurs were compared with a potential mimetic, resveratrol (RSV), a polyphenol naturally found in grapes. We hypothesized that both CR and RSV impact oxidative DNA and RNA damage compared to standard-fed control (CTL) animals. Adult (3-4 years old) male mouse lemurs were assigned to three dietary groups: a CTL group, a CR group receiving 30% fewer calories than the CTL and a RSV group receiving the CTL diet supplemented with RSV (200 mg·day(-1)·kg(-1)). Oxidative stress was estimated after 3, 9, 15 and 21 months of treatment using the measurement of oxidized nucleosides in urine samples by mass spectrometry. The resting metabolic rate, adjusted for changes in body composition, was also measured to assess the potential relationship between oxygen consumption and oxidative damage markers. This study provides evidence for oxidative stress accumulation with age in grey mouse lemur. Dietary interventions resulted in a short-term increase in oxidative stress levels followed by reduced levels with increasing age. Moreover, in this photoperiod-dependent heterotherm primate, seasonal variations in oxidative stress were observed, which was likely due to a season-dependent, cost-benefit trade-off between torpor use and oxidative stress.

Protective effect of luteolin on an oxidative-stress model induced by microinjection of sodium nitroprusside in mice

Accumulating lines of evidence showed that luteolin, a polyphenolic compound, has potent neuroprotective effects. The purpose of this study was to examine whether luteolin can protect against sodium nitroprusside (SNP)-induced oxidative damage in mouse brain. Intrastriatal co-injection of luteolin (3 - 30 nmol) with SNP (10 nmol) dose-dependently protected against brain damage and motor dysfunction. Oral administrations of luteolin (600 - 1200 mg/kg) dose-dependently protected against brain damage and motor dysfunction induced by striatal injection of SNP. Furthermore, luteolin (30 - 100 μM) concentration dependently protected against Fe(2+)-induced lipid peroxidation in mouse brain homogenate. Luteolin (1 - 100 μg/ml) showed potent DPPH radical scavenging ability, when compared with ascorbic acid and glutathione. Finally, a ferrozine assay showed that luteolin (30 - 100 μg/ml) has Fe(2+)-chelating ability, but this was weaker than that of ethylenediaminetetraacetic acid. These results suggest that intrastriatal or oral administration of luteolin protected mice brain from SNP-induced oxidative damage by scavenging and chelating effects.

Oxidative stress mediated-alterations of the microRNA expression profile in mouse hippocampal neurons

Oxidative stress plays a critical role in the etiology and pathogenesis of neurodegenerative disorders, and the molecular mechanisms that control the neuron response to ROS have been extensively studied. However, the oxidative stress-effect on miRNA expression in hippocampal neurons has not been investigated, and little is known on the effect of ROS-modulated miRNAs on cell function. In this study, H₂O₂ was used to stimulate the mouse primary hippocampal neurons to develop an oxidative stress cell model. The alterations of miRNAs expression were detected by microarray analysis and five miRNAs were validated by real-time RT-PCR. The bioinformatic analysis of deregulated miRNAs was performed to determine their potential roles in the pathogenesis of neurological disorders. We found that H₂O₂ mediated a total of 101 deregulated miRNAs, which mainly took part in the regulation of the MAPK pathway. Among them, miR-135b and miR-708 were up-regulated significantly and their targets were predicted to be involved in DNA recombination, protein ubiquitination, protein autophosphorylation and development of neurons. These results demonstrated that oxidative stress alters the miRNA expression profile of hippocampal neurons, and the deregulated miRNAs might play a potential role in the pathogenesis of neurodegenerative diseases, such as Alzheimer’s disease (AD).