Oxidative nerve cell death in Alzheimer's disease and stroke: antioxidants as neuroprotective compounds

Multi-Targeting Phytochemicals for Alzheimer's Disease

Alzheimer's disease (AD) is a type of neurodegenerative illness in which β-amyloid (Aβ) and tau protein accumulate in neurons in the form of tangles. The pathophysiological pathway of AD consists of Aβ-amyloid peptides, tau proteins, and oxidative stress in neurons and increased neuro-inflammatory response. Food and Drug Administration in the United States has authorized various drugs for the effective treatment of AD, which include galantamine, rivastigmine, donepezil, memantine, sodium oligomannate, lecanemab, and aducanumab. The major disadvantage of these drugs is that they only provide "symptomatic" relief. They are most effective in the early stages or for mild to moderate cases of the disease, but are not suitable for long-term use. Besides conventional therapies, phytochemicals have the potential to stop the progression of AD. According to research, the use of potential phytochemicals against AD has gained attention due to their potent anti-inflammatory, antioxidant, anti-hyperphosphorylation of the tau protein, metal chelation, and anti-amyloid properties. This study seeks to provide an up-to-date compilation of the most current and promising breakthroughs in AD therapy using phytochemicals. It could be concluded that phytochemicals light serve as an effective therapy for AD. However, more mechanistic investigations are needed to determine the clinical implications of phytochemicals in AD treatment.

Synthesis and biological evaluation of C-4 substituted phenoxazine-bearing hydroxamic acids with potent class II histone deacetylase inhibitory activities

Class II histone deacetylases (HDACs) are considered as potential targets to treat Alzheimer's disease (AD). Previously, C-3 substituted phenothiazine-containing compounds with class II HDAC-inhibiting activities was found to promote neurite outgrowth. This study replaced phenothiazine moiety with phenoxazine that contains many C-3 and C-4 substituents. Some resulting compounds bearing the C-4 substituent on a phenoxazine ring displayed potent class II HDAC inhibitory activities. Structure-activity relationship (SAR) of these compounds that inhibited HDAC isoenzymes was disclosed. Molecular modelling analysis demonstrates that the potent activities of C-4 substituted compounds probably arise from π-π stacked interactions between these compounds and class IIa HDAC enzymes. One of these, compound 7d exhibited the most potent class II HDAC inhibition (IC₅₀= 3-870 nM). Notably, it protected neuron cells from H₂O₂-induced neuron damage at sub-μM concentrations, but with no significant cytotoxicity. These findings show that compound 7d is a lead compound for further development of anti-neurodegenerative agents.

Neuroprotective Effect of Vitamin D on Behavioral and Oxidative Parameters of Male and Female Adult Wistar Rats Exposed to Mancozeb (manganese/zinc ethylene bis-dithiocarbamate)

The constant exposure of rural workers to pesticides is a serious public health problem. Mancozeb (MZ) is a pesticide  linked to hormonal, behavioral, genetic, and neurodegenerative effects, mainly related to oxidative stress. Vitamin D is a promising molecule that acts as a protector against brain aging. This study aimed to evaluate the neuroprotective role of vitamin D in adult male and female Wistar rats exposed to MZ. Animals received 40 mg/kg of MZ i.p. and 12.5 μg/kg or 25 μg/kg vitamin D by gavage, twice a week, for 6 weeks. The concentration of manganese had a significant increase in the hippocampus of both sexes and in the striatum of females, unlike zinc, which did not show a significant increase. MZ poisoning led to mitochondrial changes in brain tissues and promoted anxiogenic effects, especially in females. Alterations in antioxidant enzymes, mainly in the catalase activity were observed in intoxicated rats. Taken together, our results showed that exposure to MZ leads to the accumulation of manganese in brain tissues, and the behavior and metabolic/oxidative impairment were different between the sexes. Furthermore, the administration of Vitamin D was effective in preventing the damage caused by the pesticide.

Multi-Target Mechanisms of Phytochemicals in Alzheimer’s Disease: Effects on Oxidative Stress, Neuroinflammation and Protein Aggregation

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by a tangle-shaped accumulation of beta-amyloid peptide fragments and Tau protein in brain neurons. The pathophysiological mechanism involves the presence of Aβ-amyloid peptide, Tau protein, oxidative stress, and an exacerbated neuro-inflammatory response. This review aims to offer an updated compendium of the most recent and promising advances in AD treatment through the administration of phytochemicals. The literature survey was carried out by electronic search in the following specialized databases PubMed/Medline, Embase, TRIP database, Google Scholar, Wiley, and Web of Science regarding published works that included molecular mechanisms and signaling pathways targeted by phytochemicals in various experimental models of Alzheimer’s disease in vitro and in vivo. The results of the studies showed that the use of phytochemicals against AD has gained relevance due to their antioxidant, anti-neuroinflammatory, anti-amyloid, and anti-hyperphosphorylation properties of Tau protein. Some bioactive compounds from plants have been shown to have the ability to prevent and stop the progression of Alzheimer’s.

Computational Insights into the Regeneration of Ovothiol and Ergothioneine and Their Selenium Analogues by Glutathione

Ovothiol and ergothioneine are powerful antioxidants that readily react with oxidants by forming their respective disulfides. In fact, ovothiol is widely considered one of the most powerful natural antioxidants. However, for these antioxidants to be again involved in reacting with oxidants, they must be regenerated via the reduction of the disulfide bonds. In the present work, the regeneration of the antioxidants ovothiol and ergothioneine and their selenium analogues, by the closed-shell nucleophilic attack of glutathione, was investigated using density functional theory. From the calculated thermodynamic data, the attack of glutathione on OSSO and EYYE (where Y = S and/or Se) will readily occur in solution. Moreover, in comparison to the reference reaction GSH + GSSG → GSSG + GSH, all reactions are expected to be faster. Overall, the results presented herein show that the key antioxidant GSH should readily recycle ovothiol, ovoselenol, ergothioneine, and ergoseloneine from OYYO and EYYE (where Y = S and/or Se).

The tocopherol transfer protein TTP mediates Vitamin Vitamin E trafficking between cerebellar astrocytes and neurons

Alpha-tocopherol (vitamin E) is an essential nutrient that functions as a major lipid-soluble antioxidant in humans. The tocopherol transfer protein (TTP) binds α-tocopherol with high affinity and selectivity and regulates whole-body distribution of the vitamin. Heritable mutations in the TTPA gene result in familial vitamin E deficiency, elevated indices of oxidative stress, and progressive neurodegeneration that manifest primarily in spinocerebellar ataxia. Although the essential role of vitamin E in neurological health has been recognized for over 50 years, the mechanisms by which this essential nutrient is transported in the central nervous system are poorly understood. Here we found that, in the murine cerebellum, TTP is selectively expressed in GFAP-positive astrocytes, where it facilitates efflux of vitamin E to neighboring neurons. We also show that induction of oxidative stress enhances the transcription of the TtpA gene in cultured cerebellar astrocytes. Furthermore, secretion of vitamin E from astrocytes is mediated by an ABC-type transporter, and uptake of the vitamin into neurons involves the low-density lipoprotein receptor-related protein 1 (LRP1) receptor. Taken together, our data indicate that TTP-expressing astrocytes control the delivery of vitamin E from astrocytes to neurons, and that this process is homeostatically responsive to oxidative stress. These are the first observations that address the detailed molecular mechanisms of vitamin E transport in the central nervous system, and these results have important implications for understanding the molecular underpinnings of oxidative stress-related neurodegenerative diseases.

Immature Persimmon Suppresses Amyloid Beta (Aβ) Mediated Cognitive Dysfunction via Tau Pathology in ICR Mice

This study confirmed the ameliorating effect of immature persimmon (Diospyros kaki) ethanolic extract (IPEE) on neuronal cytotoxicity in amyloid beta (Aβ)1-42-induced ICR mice. The administration of IPEE ameliorated the cognitive dysfunction in Aβ1-42-induced mice by improving the spatial working memory, the short-term and long-term memory functions. IPEE protected the cerebral cholinergic system, such as the acetylcholine (ACh) level and acetylcholinesterase (AChE) activity, and antioxidant system, such as the superoxide dismutase (SOD), reduced glutathione (GSH) and malondialdehyde (MDA) contents. In addition, mitochondrial dysfunction against Aβ1-42-induced toxicity was reduced by regulating the reactive oxygen species (ROS), mitochondrial membrane potential and ATP contents. In addition, IPEE regulated the expression levels of tau signaling, such as TNF-α, p-JNK, p-Akt, p-GSK3β, p-tau, p-NF-κB, BAX and caspase 3. Finally, gallic acid, ellagic acid and quercetin 3-O-(6″-acetyl-glucoside) were identified as the physiological compounds of IPEE using ultra-performance liquid chromatography ion mobility separation quadrupole time-of-flight/tandem mass spectrometry (UPLC IMS Q-TOF/MS2).

Intranasal galantamine/chitosan complex nanoparticles elicit neuroprotection potentials in rat brains via antioxidant effect

BACKGROUND

Alzheimer's disease is a common cause of dementia in the elderly. Galantamine hydrobromide (GH) is an anti-Alzheimer cholinesterase inhibitor that has an intrinsic antioxidant effect. In a previous study, GH was complexed with chitosan to prepare intranasal GH/chitosan complex nanoparticles (CX-NP2). The nanoparticles were located in rat brains 1 h after nasal administration and showed pharmacological superiority to GH nasal solution without showing histopathological toxicity.

OBJECTIVE

This study aimed to investigate whether the long-term administration of CX-NP2 leads to biochemical toxicity in rat brains compared to GH nasal solution.

METHODS

CX-NP2 dispersion and GH solution were administrated intranasally to male Wistar rats for 30 days (3 mg/kg/day). Malondialdehyde (MDA), lipid peroxidation marker, glutathione (GSH), superoxide dismutase (SOD) activity and tumor necrosis factor-α (TNF-α) were assessed in the brain extracts in all groups.

RESULTS

There was statistically insignificant difference between the CX-NP2 and GH nasal solution treated groups in all biochemical toxicity parameters assessed. Interestingly, MDA and TNF-α levels in the CX-NP2-treated group significantly decreased compared to the control group. Also, GSH level and SOD activity were significantly enhanced in CX-NP2 treated group compared to the control group.

CONCLUSIONS

CX-NP2 did not induce a statistically significant oxidative stress or neuroinflammation in rat brains after 30-day treatment, they rather elicited neuroprotective potentials.HighlightsIntranasal GH/chitosan complex nanoparticles (CX-NP2) show promising potential as a brain targeting carrier.Compared to GH nasal solution, nasal CX-NP2 formulation did not exert oxidative stress nor neuroinflammation when administered for 30 days.

Single-Nucleotide Polymorphisms in Oxidative Stress-Related Genes and the Risk of a Stroke in a Polish Population-A Preliminary Study

The present preliminary case-control study was undertaken to detect the potential association of six single nucleotide polymorphisms (SNPs) in oxidative stress-related genes: SOD2 (c.47T > C; rs4880), CAT (c.-89A > T; rs7943316), GPX4 (c.660T > A; rs713041), NOS1 (g.117803515C > T; rs1879417) and NOS2 (c.1823C > T; rs2297518 and c.-227G > C; rs10459953) and the occurrence of a stroke. The SNPs were determined using the TaqMan^® Allelic Discrimination Assay in 107 patients with strokes and 107 age- and sex-matched individuals who had not experienced cerebrovascular accidents. The T alleles of the rs4880 were positively correlated with a stroke (bootstrap OR 1.31; 1.07-1.59 95% CI). In the case of the rs713041, an association with the T allele was found (bootstrap OR 1.36; 1.12-1.67). In addition, the occurrence of a stroke was associated with the presence of the C allele of the rs1879417 (bootstrap OR 1.32; 1.09-1.61). We also found that the C/C genotype and C allele of the rs2297518 increased the risk of a stroke (bootstrap ORs 7.00; 4.34-11.29 and 4.96; 3.88-6.34, respectively). Moreover, the C allele of the rs10459953 was associated with an increased occurrence of this disease (bootstrap OR 1.31; 1.08-1.60). These results indicated that genetics variants in the SOD2, GPX4, NOS1 and NOS2 might be associated with susceptibility to strokes in the Polish population.

Memory-Enhancing Effects of Mangosteen Pericarp Water Extract through Antioxidative Neuroprotection and Anti-Apoptotic Action

Mangosteen has long been utilized as a traditional medicine in Southeast Asia. Diverse extracts of mangosteen pericarp and its bioactive xanthones exhibit various bioactivities. However, the pharmacological potential of mangosteen pericarp water extract (MPW) has not been reported yet. This study used primary cultured rat cortical cells to investigate the effect of MPW on neurotoxicity. We found that MPW inhibited neurotoxicity and production of reactive oxygen species triggered by Aβ_(25–35) or excitatory amino acids. MPW inhibited caspase 3 activation and DNA fragmentation in Aβ_(25–35)- or N-methyl-D-aspartate-treated cells, suggesting an anti-apoptotic action. Additionally, MPW reduced lipid peroxidation and scavenged 1,1-diphenyl-2-picrylhydrazyl radicals, assuring its antioxidant property. Furthermore, MPW suppressed β-secretase and acetylcholinesterase activities. These findings prompted us to evaluate its effect on memory dysfunction in scopolamine-treated mice using Morris water maze test. Oral administration of MPW at the dosage of 50, 100, or 300 mg/kg for four days significantly decreased the latency time to find the platform and markedly increased the swimming time in the target quadrant. Taken together, our results suggest that MPW exerts memory-enhancing effect through antioxidative neuroprotection and anti-apoptotic action. Accordingly, MPW may have a potential to prevent or treat memory impairment associated with Alzheimer’s disease.

Role of antioxidants and a nutrient rich diet in Alzheimer's disease

The joint attack on the body by metabolic acidosis and oxidative stress suggests that treatment in degenerative diseases, including Alzheimer's disease (AD), may require a normalizing of extracellular and intracellular pH with simultaneous supplementation of an antioxidant combination cocktail at a sufficiently high dose. Evidence is also accumulating that combinations of antioxidants may be more effective, taking advantage of synergistic effects of appropriate antioxidants as well as a nutrient-rich diet to prevent and reverse AD. This review focuses on nutritional, nutraceutical and antioxidant treatments of AD, although they can also be used in other chronic degenerative and neurodegenerative diseases.

Identification of caffeic acid and rutin by UHPLC MS/MS and antioxidant activity of Commelina erecta Lineu. in cell culture

The Commelina erecta L. (C. erecta) also known as erva-de-santa-luzia is reported by local population to have medical properties against some pathological conditions. In this study, two extracts of C. erecta leaves (aqueous and ethanolic) were phytochemically analysed and evaluated for their in-vitro antioxidant activities by DPPH, TBARS, NO assays and cell viability assays. The ultra-high performance liquid chromatography followed by tandem mass spectrometry analysis showed the presence of rutin and caffeic acid in aqueous and ethanolic extract. The total polyphenols in aqueous and ethanolic extracts found were 142.7 ± 3.0 and 123.1 ± 5.8 μg/mL of GAE, respectively. The ethanolic extract (5 mg/mL) inhibits TBARS by 33.8%, and the aqueous extract (5 mg/mL) exhibited scavenger property against nitric oxide derivatives to an extent of 77.8%. In cell culture, both extracts improved cell survivability under H2O2 induced oxidative stress. Thus, C. erecta extract is a good candidate to become a phytotherapic medicine.

Carvacrol and Thymol Attenuate Cytotoxicity Induced by Amyloid β25-35 via Activating Protein Kinase C and Inhibiting Oxidative Stress in PC12 Cells

Background

Our previous findings indicated that carvacrol and thymol alleviate cognitive impairments caused by Aβ in rodent models of Alzheimer's disease (AD). In this study, the neuroprotective effects of carvacrol and thymol against Aβ25-35-induced cytotoxicity were evaluated, and the potential mechanisms were determined.

Methods

PC12 cells were pretreated with Aβ25-35 for 2 h, followed by incubation with carvacrol or thymol for additional 48 h. Cell viability was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. A flurospectrophotometer was employed to observe the intracellular reactive oxygen species (ROS) production. Protein kinase C (PKC) activity was analyzed using ELISA.

Results

Our results indicated that carvacrol and thymol could significantly protect PC12 cells against Aβ25-35-induced cytotoxicity. Furthermore, Aβ25-35 could induce intracellular ROS production, while carvacrol and thymol could reverse this effect. Moreover, our findings showed that carvacrol and thymol elevate PKC activity similar to Bryostatin-1, as a PKC activator.

Conclusion

This study provided the evidence regarding the protective effects of carvacrol and thymol against Aβ25–35-induced cytotoxicity in PC12 cells. The results suggested that the neuroprotective effects of these compounds against Aβ25-35 might be through attenuating oxidative damage and increasing the activity of PKC as a memory-related protein. Thus, carvacrol and thymol were found to have therapeutic potential in preventing or modulating AD.

Adhesion Molecule L1 Agonist Mimetics Protect Against the Pesticide Paraquat-Induced Locomotor Deficits and Biochemical Alterations in Zebrafish

Besides several endogenous elements, exogenous factors, including exposure to pesticides, have been recognized as putative factors contributing to the onset and development of neurodegenerative diseases, including Parkinson's disease (PD). Considering the availability, success rate, and limitations associated with the current arsenals to fight PD, there is an unmet need for novel therapeutic interventions. Therefore, based on the previously reported beneficial functions of the L1 cell adhesion molecule, we hypothesized that L1 mimetic compounds may serve to neutralize neurotoxicity triggered by the pesticide paraquat (PQ). In this study, we attempt to use PQ for inducing PD-like pathology and the L1 mimetic compounds phenelzine sulfate (PS) and tacrine (TC) as potential candidates for the amelioration of PD symptoms using zebrafish as a model system. Administration of PQ together with the L1 mimetic compounds PS or TC (250 nM) improved survival of zebrafish larvae, protected them from locomotor deficits, and increased their sensorimotor reflexes. Moreover, application of PQ together with PS (500 nM) or TC (1000 nM) in adult zebrafish counteracted PQ-induced toxicity, maintaining normal locomotor functions and spatial memory in an open field and T-maze task, respectively. Both L1 mimetic compounds prevented reduction in tyrosine hydroxylase and dopamine levels, reduced reactive oxygen species (ROS) generation, protected against impairment of mitochondrial viability, improved the antioxidant enzyme system, and prevented a decrease in ATP levels. Altogether, our findings highlight the beneficial functions of the agonistic L1 mimetics PS and TC by improving several vital cell functions against PQ-triggered neurotoxicity.

Adhesion Molecule L1 Agonist Mimetics Protect Against the Pesticide Paraquat-Induced Locomotor Deficits and Biochemical Alterations in Zebrafish

Besides several endogenous elements, exogenous factors, including exposure to pesticides, have been recognized as putative factors contributing to the onset and development of neurodegenerative diseases, including Parkinson's disease (PD). Considering the availability, success rate, and limitations associated with the current arsenals to fight PD, there is an unmet need for novel therapeutic interventions. Therefore, based on the previously reported beneficial functions of the L1 cell adhesion molecule, we hypothesized that L1 mimetic compounds may serve to neutralize neurotoxicity triggered by the pesticide paraquat (PQ). In this study, we attempt to use PQ for inducing PD-like pathology and the L1 mimetic compounds phenelzine sulfate (PS) and tacrine (TC) as potential candidates for the amelioration of PD symptoms using zebrafish as a model system. Administration of PQ together with the L1 mimetic compounds PS or TC (250 nM) improved survival of zebrafish larvae, protected them from locomotor deficits, and increased their sensorimotor reflexes. Moreover, application of PQ together with PS (500 nM) or TC (1000 nM) in adult zebrafish counteracted PQ-induced toxicity, maintaining normal locomotor functions and spatial memory in an open field and T-maze task, respectively. Both L1 mimetic compounds prevented reduction in tyrosine hydroxylase and dopamine levels, reduced reactive oxygen species (ROS) generation, protected against impairment of mitochondrial viability, improved the antioxidant enzyme system, and prevented a decrease in ATP levels. Altogether, our findings highlight the beneficial functions of the agonistic L1 mimetics PS and TC by improving several vital cell functions against PQ-triggered neurotoxicity.

Assessing the therapeutic potential of Graptopetalum paraguayense on Alzheimer's disease using patient iPSC-derived neurons

Alzheimer’s disease (AD) is the most common type of dementia and also one of the leading causes of death worldwide. However, the underlying mechanisms remain unclear, and currently there is no drug treatment that can prevent or cure AD. Here, we have applied the advantages of using induced pluripotent stem cell (iPSC)-derived neurons (iNs) from AD patients, which are able to offer human-specific drug responsiveness, in order to evaluate therapeutic candidates for AD. Using approach involving an inducible neurogenin-2 transgene, we have established a robust and reproducible protocol for differentiating human iPSCs into glutamatergic neurons. The AD-iN cultures that result have mature phenotypic and physiological properties, together with AD-like biochemical features that include extracellular β-amyloid (Aβ) accumulation and Tau protein phosphorylation. By screening using a gene set enrichment analysis (GSEA) approach, Graptopetalum paraguayense (GP) has been identified as a potential therapeutic agent for AD from among a range of Chinese herbal medicines. We found that administration of a GP extract caused a significantly reduction in the AD-associated phenotypes of the iNs, including decreased levels of extracellular Aβ40 and Aβ42, as well as reduced Tau protein phosphorylation at positions Ser214 and Ser396. Additionally, the effect of GP was more prominent in AD-iNs compared to non-diseased controls. These findings provide valuable information that suggests moving extracts of GP toward drug development, either for treating AD or as a health supplement to prevent AD. Furthermore, our human iN-based platform promises to be a useful strategy when it is used for AD drug discovery.

Acute Exposure to Permethrin Modulates Behavioral Functions, Redox, and Bioenergetics Parameters and Induces DNA Damage and Cell Death in Larval Zebrafish

Permethrin (PM) is a synthetic pyrethroid insecticide widely used as domestic repellent. Damage effects to nontarget organisms have been reported, particularly in the early stages of development. Studies indicate redox unbalance as secondary PM effect. Therefore, our goal was to investigate the acute PM effects on larval zebrafish. Larvae (6 days postfertilization) were exposed to PM (25–600 μg/L) during 24 hours, and 50% lethal concentration was estimated. For subsequent assays, the sublethal PM concentrations of 25 and 50 μg/L were used. PM increased anxiety-like behaviors according to the Novel Tank and Light-Dark tests. At the molecular level, PM induced increased ROS, which may be related to the increased lipid peroxidation, DNA damage, and apoptosis detected in PM-exposed organisms. In parallel, upregulation of the antioxidant system was detected after PM exposure, with increased superoxide dismutase, glutathione S-transferase and glutathione reductase activities, and thiol levels. The increased of Nrf2 target genes and the activation of an electrophile response element-driven reporter Tg(EPRE:LUC-EGFP) suggest that the Nrf2 pathway can mediate a fast response to PM, leading to antioxidant amplification. By using high-resolution respirometry, we found that exposure to PM decreased the oxygen consumption in all respiratory stages, disrupting the oxidative phosphorylation and inhibiting the electron transfer system, leading to decrease in bioenergetics capacity. In addition, PM led to increases of residual oxygen consumption and changes in substrate control ratio. Glucose metabolism seems to be affected by PM, with increased lactate dehydrogenase and decreased citrate synthase activities. Taken together, our results demonstrated the adverse effects of acute sublethal PM concentrations during larval development in zebrafish, causing apparent mitochondrial dysfunction, indicating a potential mechanism to redox unbalance and oxidative stress, which may be linked to the detected cell death and alterations in normal behavior patterns caused by acute PM exposure.

The Importance of Gender-Related Anticancer Research on Mitochondrial Regulator Sodium Dichloroacetate in Preclinical Studies In Vivo

Sodium dichloroacetate (DCA) is an investigational medicinal product which has a potential anticancer preparation as a metabolic regulator in cancer cells’ mitochondria. Inhibition of pyruvate dehydrogenase kinases by DCA keeps the pyruvate dehydrogenase complex in the active form, resulting in decreased lactic acid in the tumor microenvironment. This literature review displays the preclinical research data on DCA’s effects on the cell pyruvate dehydrogenase deficiency, pyruvate mitochondrial oxidative phosphorylation, reactive oxygen species generation, and the Na⁺–K⁺–2Cl⁻ cotransporter expression regulation in relation to gender. It presents DCA pharmacokinetics and the hepatocarcinogenic effect, and the safety data covers the DCA monotherapy efficacy for various human cancer xenografts in vivo in male and female animals. Preclinical cancer researchers report the synergistic effects of DCA combined with different drugs on cancer by reversing resistance to chemotherapy and promoting cell apoptosis. Researchers note that female and male animals differ in the mechanisms of cancerogenesis but often ignore studying DCA’s effects in relation to gender. Preclinical gender-related differences in DCA pharmacology, pharmacological mechanisms, and the elucidation of treatment efficacy in gonad hormone dependency could be relevant for individualized therapy approaches so that gender-related differences in treatment response and safety can be proposed.

Panax Notoginseng Saponins Ameliorate Aβ-Mediated Neurotoxicity in C. elegans through Antioxidant Activities

The deposition of amyloid beta (Aβ) is the main hallmark of Alzheimer's disease (AD) and there is no effective drug to cure the progressive cognitive loss or memory deficits caused by the aggregative toxicity of Aβ protein. Oxidative stress has been hypothesized to play a role in progressive neurodegenerative diseases like AD. Panax notoginseng saponin (PNS) from the rhizome of "pseudo-ginseng" exhibits potent antioxidant effects on aging process in neuron cells and animals. By using C. elegans as an ideal model organism, the present study shows that PNS (0.5-4 mg/mL) can significantly inhibit AD-like symptoms of worm paralysis and enhance resistance to oxidative stress induced by paraquat and aging conditions. Additionally, PNS extends lifespan and maintains healthspan of C. elegans by improving the swimming prowess and fertility at old age. It markedly activates the expression of SKN-1 mRNA, which further supports SKN-1 signaling pathway which is involved in the therapeutic effect of PNS on AD C. elegans. Our results provide direct evidence on PNS for treating AD on gene level and theoretical foundation for reshaping medicinal products of PNS in the future.

Green Tea Seed Oil Suppressed Aβ1⁻42-Induced Behavioral and Cognitive Deficit via the Aβ-Related Akt Pathway

The aim of this study was to investigate the availability of seeds, one of the byproducts of green tea, and evaluate the physiological activity of seed oil. The ameliorating effect of green tea seed oil (GTO) was evaluated on H₂O₂-induced PC12 cells and amyloid beta (Aβ)_1–42-induced ICR mice. GTO showed improvement of cell viability and reduced reactive oxygen species (ROS) production in H₂O₂-induced PC12 cells by conducting the 2′,3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and 2′,7′-dichlorofluorescein diacetate (DCF-DA) analysis. Also, administration of GTO (50 and 100 mg/kg body weight) presented protective effects on behavioral and memory dysfunction by conducting Y-maze, passive avoidance, and Morris water maze tests in Aβ-induced ICR mice. GTO protected the antioxidant system by reducing malondialdehyde (MDA) levels, and by increasing superoxide dismutase (SOD) and reducing glutathione (GSH) contents. It significantly regulated the cholinergic system of acetylcholine (ACh) contents, acetylcholinesterase (AChE) activities, and AChE expression. Also, mitochondrial function was improved through the reduced production of ROS and damage of mitochondrial membrane potential (MMP) by regulating the Aβ-related c-Jun N-terminal kinase (JNK)/protein kinase B (Akt) and Akt/apoptosis pathways. This study suggested that GTO may have an ameliorating effect on cognitive dysfunction and neurotoxicity through various physiological activities.

Assessment of Improvement in Oxidative Stress Indices with Resocialization in Memory Retrieval in Y-Maze in Male Rats

Introduction:

Memory deficit is an important issue in some psychiatric diseases either as a primary symptom or as a comorbid symptom. Factors that determine the decline or improvement of memory are an important subject to reduce the severity of these diseases.

Methods and materials:

In this study, 32 male Sprague-Dawley rats were randomly divided into 4 experimental groups: social (control), isolation, resocialization for 3 days, and resocialization for 7 days. Isolation occurred for 14 days. Resocialization groups were resocialized for 3 or 7 days after isolation. In the social group, there was no intervention with normal socializing among the rats. In the isolation group, rats were isolated with no resocialization. In all 4 groups, after performing the Y-maze, the rats’ brains were removed to assess oxidative stress status in the hippocampus and prefrontal cortex.

Results:

Y-maze performance improved after 3 and 7 days of resocialization. However, oxidative stress status for malondialdehyde, glutathione and nitrite/nitrate returned to normal levels except in 2 experiments after 7 days of resocialization. In addition, in 2 experiments, just glutathione in the prefrontal cortex and nitrite/nitrate in the hippocampus after 3 days of resocialization improved.

Conclusions:

A return to normal levels in all types of antioxidant markers in the resocialization groups is not the only factor for improving memory deficits resulting from isolation. Resocialization may also be activating other regulatory mechanisms besides an antioxidant defense.

Anti-amyloidogenic properties of an ethyl acetate fraction from Actinidia arguta in Aβ1-42-induced ICR mice

This study aimed to investigate the ameliorating effect of an ethyl acetate fraction from the fruit Actinidia arguta (EFAA) on amyloid beta (Aβ)-induced neurotoxicity and cognitive deficits in ICR mice. EFAA showed potent protective effects against Aβ-induced neurotoxicity through 2',7'-dichlorofluorescein diacetate (DCF-DA), 2',3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) release into the assay medium. EFAA treatment reduced the intracellular ROS level and lactate dehydrogenase (LDH) release in the mitochondria, and increased cell viability in Aβ-induced neuroblastoma MC-IXC cells. The administration of EFAA significantly attenuated Aβ-induced learning and memory deficits, which were evaluated by Y-maze, passive avoidance, and Morris water maze tests. Furthermore, EFAA showed the ameliorating effect of cholinergic functions by increasing acetylcholine (ACh) levels and decreasing acetylcholinesterase (AChE) activity, and protected antioxidant systems by increasing superoxide dismutase (SOD) and decreasing the oxidized glutathione (GSH)/total GSH and malondialdehyde (MDA) in the brain. Finally, EFAA prevented mitochondrial dysfunction via regulating apoptotic signaling molecules including phosphorylated Akt (p-Akt), phosphorylated tau (p-tau), Bax, and cytochrome c in the brain tissues. Therefore, the present study suggests that EFAA might be a potential source of natural antioxidants with the ability to ameliorate Aβ-induced amnesia.

Differential Effect of Acute Iron Overload on Oxidative Status and Antioxidant Content in Regions of Rat Brain

The hypothesis of this study is that the cerebral cortex, hippocampus, and striatum of the rat brain are differentially affected in terms of oxidative stress and antioxidant capacity by acute Fe overload because Fe is distributed in a heterogeneous fashion among different regions and cells of the brain. The effects on the lipophilic and hydrophilic cellular environment were compared between regions and with the whole brain. A single dose of Fe-dextran increased Fe deposits, reaching a maximum after 6 hr. Both in whole brain and in cortex region, the ascorbyl/ascorbate content ratio was increased after 6 hr of Fe administration, while in striatum and hippocampus, there was no significant changes after Fe overload. Total thiol content decreased in whole brain and cortex, while there were no significant changes in striatum and hippocampus after Fe overload. The content of α-tocopherol (α-T), whether measured in the whole brain or in the isolated regions, did not change following Fe treatment. Lipid radical (LR•) generation rate after Fe-dextran overload only increased in the cortex region. The LR•/α-T content ratio was increased by Fe treatment in cortex but not in the whole brain, striatum, or hippocampus, in agreement with the study tested hypothesis.

Carotenoids as Potential Antioxidant Agents in Stroke Prevention: A Systematic Review

Stroke and other cerebrovascular diseases are among the most common causes of death worldwide. Prevention of modifiable risk factors is a cost-effective approach to decrease the risk of stroke. Oxidative stress is regarded as the major flexible operative agent in ischemic brain damage. This review presents recent scientific advances in understanding the role of carotenoids as antioxidants in lowering stroke risk based on observational studies. We searched Medline using the following terms: (Carotenoids [MeSH] OR Carotenes [tiab] OR Carotene [tiab] OR "lycopene [Supplementary Concept]" [MeSH] OR lycopene [tiab] OR beta-Carotene [tiab]) AND (stroke [MeSH] OR stroke [tiab] OR "Cerebrovascular Accident" [tiab] OR "Cerebrovascular Apoplexy" [tiab] OR "Brain Vascular Accident" [tiab] OR "Cerebrovascular Stroke" [tiab]) AND ("oxidative stress" [MeSH] OR "oxidative stress"[tiab]). This search considered papers that had been published between 2000 and 2017. Recent studies indicated that high dietary intake of six main carotenoids (i.e., lycopene, <- and®-carotene, lutein, zeaxanthin, and astaxanthin) was associated with reduced risk of stroke and other cardiovascular outcomes. However, the main mechanism of the action of these nutrients was not identified, and multiple mechanisms except antioxidant activity were suggested to be involved in the observed beneficial effects. The dietary intake of six major carotenoids should be promoted as this may have a substantial positive effect on stroke prevention and stroke mortality reduction.

Argininic acid alters markers of cellular oxidative damage in vitro: Protective role of antioxidants

We, herein, investigated the in vitro effects of argininic acid on thiobarbituric acid-reactive substances (TBA-RS), total sulfhydryl content and on the activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in the blood, kidney and liver of 60-day-old rats. We also verified the influence of the antioxidants (each at 1.0mM) trolox and ascorbic acid, as well as of N^G-nitro-l-arginine methyl ester (L-NAME) at 1.0mM, a nitric oxide synthase inhibitor, on the effects elicited by argininic acid on the parameters tested. The liver, renal cortex and renal medulla were homogenized in 10vol (1:10w/v) of 20mM sodium phosphate buffer, pH 7.4, containing 140mM KCl; and erythrocytes and plasma were prepared from whole blood samples obtained from rats. For in vitro experiments, the samples were pre-incubated for 1h at 37°C in the presence of argininic acid at final concentrations of 0.1, 1.0 and 5.0μM. Control experiments were performed without the addition of argininic acid. Results showed that argininic acid (5.0μM) enhanced CAT and SOD activities and decreased GSH-Px activity in the erythrocytes, increased CAT and decreased GSH-Px activities in the renal cortex and decreased CAT and SOD activities in the renal medulla of 60-day-old rats, as compared to the control group. Antioxidants and/or L-NAME prevented most of the alterations caused by argininic acid on the oxidative stress parameters evaluated. Data suggest that argininic acid alters antioxidant defenses in the blood and kidney of rats; however, in the presence of antioxidants and L-NAME, most of these alterations in oxidative stress were prevented. These findings suggest that oxidative stress may be make an important contribution to the damage caused by argininic acid in hyperargininemic patients and that treatment with antioxidants may be beneficial in this pathology.

Sodium Selenite Prevents Paraquat-Induced Neurotoxicity in Zebrafish

Considering the antioxidant properties of sodium selenite (Na₂SeO₃) and the involvement of oxidative stress events in paraquat-induced neurotoxicity, this study investigated the protective effect of dietary Na₂SeO₃ on biochemical and behavioral parameters of zebrafish exposed to paraquat (PQ). Fish were pretreated with a Na₂SeO₃ diet for 21 days and then PQ (20 mg/kg) was administered intraperitoneally with six injections for 16 days. In the novel tank test, the Na₂SeO₃ diet prevented the locomotor impairments, as well as the increase in the time spent in the top area of the tank, and the exacerbation of freezing episodes. In the preference for conspecifics and in the mirror-induced aggression (MIA) tasks, Na₂SeO₃ prevented the increase in the latency to enter the area closer to conspecifics and the agonistic behavior of PQ-treated animals, respectively. Na₂SeO₃ prevented the increase of carbonylated protein (CP), reactive oxygen species (ROS), and nitrite/nitrate (NOx) levels, as well as the decrease in non-protein thiols (NPSH) levels. Regarding the antioxidant enzymatic defenses, Na₂SeO₃ prevented the increase in catalase (CAT) and glutathione peroxidase (GPx) activities caused by PQ. Altogether, dietary Na₂SeO₃ improves behavioral and biochemical function impaired by PQ treatment in zebrafish, by modulating not only redox parameters, but also anxiety- and aggressive-like phenotypes in zebrafish.

Promises of a biocompatible nanocarrier in improved brain delivery of quercetin: Biochemical, pharmacokinetic and biodistribution evidences

In various neurological disorders, antioxidants are frequently prescribed along with the specific treatment modalities. One such promising natural flavonoid is quercetin, offering better outcomes than established vitamins E and C. Though with immense promises, various challenges like poor oral-bioavailability (<2%), extensive first-pass metabolism, poor brain permeability, hydrophobic nature and physiological pH instability hinder its proper usage. Hence, it was planned to prepare quercetin-loaded nano lipidic carriers (NLCs) employing biocompatible components like phospholipids and tocopherol acetate for enhanced brain delivery. The outcomes were also compared with solid lipid nanoparticles (SLNs) of comparable composition. Both the nanocolloids offered better drug loading and controlled drug release with appreciable stability. In vitro antioxidant performance was improved after encapsulation in nanoparticles and the nanoparticles were substantially uptaken by Caco-2 cells. The difference in outcomes was vivid in pharmacokinetic studies, where nanoparticles, esp. NLCs substantially enhanced the relative bioavailability (approx. 6 folds), biological residence (2.5 times) and appreciably retarded the drug clearance (approx. 6 folds). On the other hand, both nanoparticles were able to substantially deliver the drug to brain. NLCs were observed to enhance the brain permeability of drug in a noticeable manner. In Conclusion, SLNs/NLCs can offer a better-platform for brain-delivery of quercetin.

Dietary Antioxidants and Human Cancer

Epidemiological studies show that a high intake of anti-oxidant-rich foods is inversely related to cancer risk. While animal and cell cultures confirm the anticancer effects of antioxidants, intervention trials to determine their ability to reduce cancer risk have been inconclusive, although selenium and vitamin E reduced the risk of some forms of cancer, including prostate and colon cancer, and carotenoids have been shown to help reduce breast cancer risk. Cancer treatment by radiation and anticancer drugs reduces inherent antioxidants and induces oxidative stress, which increases with disease progression. Vitamins E and C have been shown to ameliorate adverse side effects associated with free radical damage to normal cells in cancer therapy, such as mucositis and fibrosis, and to reduce the recurrence of breast cancer. While clinical studies on the effect of anti-oxidants in modulating cancer treatment are limited in number and size, experimental studies show that antioxidant vitamins and some phytochemicals selectively induce apoptosis in cancer cells but not in normal cells and prevent angiogenesis and metastatic spread, suggesting a potential role for antioxidants as adjuvants in cancer therapy.

Protocatechualdehyde Protects Against Cerebral Ischemia-Reperfusion-Induced Oxidative Injury Via Protein Kinase Cε/Nrf2/HO-1 Pathway

Oxidative stress is closely related to the pathogenesis of ischemic stroke. Protocatechualdehyde (PCA) is a phenolic acid compound that has the putative antioxidant activities. The present study was aimed to investigate the molecular mechanisms involved in the antioxidative effect of PCA against cerebral ischemia/reperfusion (I/R) injury. The experiment stroke model was produced in Sprague-Dawley rats via middle cerebral artery occlusion (MCAO). To model ischemia-like conditions in vitro, differentiated SH-SY5Y cells were exposed to transient oxygen and glucose deprivation (OGD). Treatment with PCA significantly improved neurologic score, reduced infarct volume and necrotic neurons, and also decreased reactive oxygen species (ROS) production, 4-hydroxynonenal (4-HNE), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) contents at 24 h after reperfusion. Meanwhile, PCA significantly increased the transcription nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expressions in the ischemic cerebral cortex as shown by immunofluorescence staining and Western blot analysis. In vitro experiment showed that PCA protected differentiated SH-SY5Y cells against OGD-induced injury. Likewise, PCA also increased markedly the Nrf2 and HO-1 expressions in a dose-dependent manner. The neuroprotection effect of PCA was abolished by knockdown of Nrf2 and HO-1. Moreover, knockdown of protein kinase Cε (PKCε) also blocked PCA-induced Nfr2 nuclear translocation, HO-1 expression, and neuroprotection. Taken together, these results provide evidences that PCA can protect against cerebral ischemia-reperfusion-induced oxidative injury, and the neuroprotective effect involves the PKCε/Nrf2/HO-1 pathway.

Phenylketonuria Pathophysiology: on the Role of Metabolic Alterations

Phenylketonuria (PKU) is an inborn error of phenylalanine (Phe) metabolism caused by the deficiency of phenylalanine hydroxylase. This deficiency leads to the accumulation of Phe and its metabolites in tissues and body fluids of PKU patients. The main signs and symptoms are found in the brain but the pathophysiology of this disease is not well understood. In this context, metabolic alterations such as oxidative stress, mitochondrial dysfunction, and impaired protein and neurotransmitters synthesis have been described both in animal models and patients. This review aims to discuss the main metabolic disturbances reported in PKU and relate them with the pathophysiology of this disease. The elucidation of the pathophysiology of brain damage found in PKU patients will help to develop better therapeutic strategies to improve quality of life of patients affected by this condition.

Oligodendrocytes and Alzheimer's disease

Extensive evidence has indicated that the breakdown of myelin is associated with Alzheimer's disease (AD) since the vulnerability of oligodendrocytes under Alzheimer's pathology easily induces the myelin breakdown and the loss of the myelin sheath which might be the initiating step in the changes of the earliest stage of AD prior to appearance of amyloid and tau pathology. Considerable research implicated that beta-amyloid (Aβ)-mediated oligodendrocyte dysfunction and myelin breakdown may be via neuroinflammation, oxidative stress and/or apoptosis. It also seems that the oligodendrocyte dysfunction is triggered by the formation of neurofibrillary tangles (NFTs) through inflammation and oxidative stress as the common pathophysiological base. Impaired repair of oligodendrocyte precursor cells (OPCs) might possibly enhance the disease progress under decreased self-healing ability from aging process and pathological factors including Aβ pathology and/or NFTs. Thus, these results have suggested that targeting oligodendrocytes may be a novel therapeutic intervention for the prevention and treatment of AD.

Curcumin prophylaxis mitigates the incidence of hypobaric hypoxia-induced altered ion channels expression and impaired tight junction proteins integrity in rat brain

Background

The present study was proposed to elucidate the prophylactic role of curcumin in the prevention of hypoxia-induced cerebral edema (HACE).

Methods

Rats were exposed to simulated hypobaric hypoxia at 7620 m for 24 h at 25 ± 1 °C. Transvascular leakage, expression of transcriptional factors (nuclear factor-kappa B (NF-κB) and hypoxia inducible factor 1 alpha (Hif-1α) and also the genes regulated by these transcriptional factors, sodium potassium-adenosine triphosphatase (Na⁺/K⁺-ATPase) and endothelial sodium channel (ENaC) levels and brain tight junction (TJ) proteins like ZO-1, junctional adhesion molecule C (JAMC), claudin 4 and claudin 5 levels were determined in the brain of rats under hypoxia by Western blotting, electro mobility shift assay, ELISA, immunohistochemistry, and histopathology along with haematological parameters. Simultaneously, to rule out the fact that inflammation causes impaired Na⁺/K⁺-ATPase and ENaC functions and disturbing the TJ integrity leading to cerebral edema, the rats were pre-treated with curcumin (100 mg/kg body weight) 1 h prior to 24-h hypoxia.

Results

Curcumin administration to rats, under hypoxia showed a significant decrease (p < 0.001) in brain water content (3.53 ± 0.58 wet-to-dry-weight (W/D) ratio) and transvascular leakage (136.2 ± 13.24 relative fluorescence units per gram (r.f.u./g)) in the brain of rats compared to control (24-h hypoxia) (7.1 ± 1.0 W/D ratio and 262.42 ± 24.67 r.f.u./g, respectively). Curcumin prophylaxis significantly attenuated the upregulation of NF-κB (p < 0.001), thereby leading to concomitant downregulation of pro-inflammatory cytokine levels (↓IL-1, IL-2, IL-18 and TNF-α), cell adhesion molecules (↓P-selectin and E-selectin) and increased anti-inflammatory cytokine (↑IL-10). Curcumin stabilized the brain HIF-1α levels followed by maintaining VEGF levels along with upregulated Na⁺/K⁺-ATPase and ENaC levels (p < 0.001) under hypoxia. Curcumin restored the brain ZO-1, JAMC, claudin 4 and claudin 5 levels (p < 0.001) under hypoxia. Histopathological observations revealed the absence of edema and inflammation in the brain of rats supplemented with curcumin.

Conclusions

These results indicate that curcumin is a potent drug in amelioration of HACE as it effectively attenuated inflammation as well as fluid influx by maintaining the tight junction proteins integrity with increased ion channels expression in the brain of rats under hypoxia.

Nicotinamide adenine dinucleotide: An essential factor in preserving hearing in cisplatin-induced ototoxicity

Ototoxicity is an important issue in patients receiving cisplatin chemotherapy. Numerous studies have demonstrated that several mechanisms, including oxidative stress, DNA damage, and inflammatory responses, are closely associated with cisplatin-induced ototoxicity. Although much attention has been directed at identifying ways to protect the inner ear from cisplatin-induced damage, the precise underlying mechanisms have not yet been elucidated. The cofactor nicotinamide adenine dinucleotide (NAD(+)) has emerged as an important regulator of cellular energy metabolism and homeostasis. NAD(+) acts as a cofactor for various enzymes including sirtuins (SIRTs) and poly(ADP-ribose) polymerases (PARPs), and therefore, maintaining adequate NAD(+) levels has therapeutic benefits because of its effect on NAD(+)-dependent enzymes. Recent studies demonstrated that disturbance in intracellular NAD(+) levels is critically involved in cisplatin-induced cochlear damage associated with oxidative stress, DNA damage, and inflammatory responses. In this review, we describe the importance of NAD(+) in cisplatin-induced ototoxicity and discuss potential strategies for the prevention or treatment of cisplatin-induced ototoxicity with a particular focus on NAD(+)-dependent cellular pathways.

Selection and molecular characterization of a high tocopherol accumulation rice mutant line induced by gamma irradiation

Tocopherols are micronutrients with antioxidant properties. They are synthesized by photosynthetic bacteria and plants, and play important roles in animal and human nutrition. In this study, we isolated a new rice mutant line with elevated tocopherol content (MRXII) from an in vitro mutagenized population induced by gamma irradiation. The mutant exhibited greater seed longevity than the control, indicating a crucial role for tocopherols in maintaining viability during quiescence, and displayed faster seedling growth during the early growth stage. To study the molecular mechanism underlying vitamin E biosynthesis, we examined the expression patterns of seven rice genes encoding vitamin E biosynthetic enzymes. Accumulation levels of the OsVTE2 transcript and OsVTE2 protein in the MRXII mutant were significantly higher than in the control. Sequence analysis revealed that the MRXII mutant harbored a point mutation in the OsVTE2 promoter region, which resulted in the generation of MYB transcription factor-binding cis-element. These results help identify the promoter regions that regulate OsVTE2 transcription, and offer insights into the regulation of tocopherol content.

Hyperprolinemia induces DNA, protein and lipid damage in blood of rats: antioxidant protection

The present study investigated the effects of hyperprolinemia on oxidative damage to biomolecules (protein, lipids and DNA) and the antioxidant status in blood of rats. The influence of the antioxidants on the effects elicited by proline was also examined. Wistar rats received two daily injections of proline and/or vitamin E plus C (6th-28th day of life) and were killed 12h after the last injection. Results showed that hyperprolinemia induced a significant oxidative damage to proteins, lipids and DNA demonstrated by increased carbonyl content, malondialdehyde levels and a greater damage index in comet assay, respectively. The concomitant antioxidants administration to proline treatment completely prevented oxidative damage to proteins, but partially prevented lipids and DNA damage. We also observed that the non-enzymatic antioxidant potential was decreased by proline treatment and partially prevented by antioxidant supplementation. The plasma levels of vitamins E and C significantly increased in rats treated exogenously with these vitamins but, interestingly, when proline was administered concomitantly with vitamin E plus C, the levels of these vitamins were similar to those found in plasma of control and proline rats. Our findings suggest that hyperprolinemia promotes oxidative damage to the three major classes of macromolecules in blood of rats. These effects were accomplished by decrease in non-enzymatic antioxidant potential and decrease in vitamins administered exogenously, which significantly decreased oxidative damage to biomolecules studied. These data suggest that antioxidants may be an effective adjuvant therapeutic to limit oxidative damage caused by proline.

The effect of vitamin E on neuronal apoptosis in hippocampal dentate gyrus in rabbits fed with high-cholesterol diets

Background:

Hypercholesterolemia that can increase stress oxidative has destructive effects on brain functions. Vitamin E is a powerful antioxidant and its effects on decrement of oxidative stress in the diseases such as Alzheimer's and hypercholesterolemia are demonstrated. The aim of this study was evaluation of the effects of vitamin E on the level of neuronal apoptosis in granular layer of dentate gyrus in the rabbits that fed with high-cholesterol diet.

Materials and Methods:

Male New Zealand white rabbits were divided into the control, the Vitamin E (50 mg/kg; gavage), the high-cholesterol diet (containing 2% cholesterol), and the high-cholesterol diet-vitamin E groups. Serum levels of cholesterol, LDL, and HDL, before and after the regimen for 6 weeks, were measured. Then, the rabbits for immunohistochemical staining (TUNEL Test) and evaluation of neuronal apoptosis in dentate gyrus of hippocampal formation were anesthetized and brains were dissected.

Results:

Results showed that after the regimens, serum levels of cholesterol, LDL, and HDL in the cholesterol receiving groups were increased significantly (P < 0.05). Histological results demonstrated that neuronal apoptosis in the dentate gyrus of the high-cholesterol diet group was increased significantly (P < 0.05) comparing to the control group; however, vitamin E decreased apoptosis as there wasn’t any significant differences between the high-cholesterol diet-vitamin E and control groups.

Conclusions:

Present results showed that consumption of high-cholesterol diets through hypercholesterolemia and its complication can induce neuronal death in hippocampus and probable resulting cognition disorders; however, vitamin E has neuroprotective effects and prevents neuronal apoptosis significantly.

Anti-oxidative effects of Rooibos tea (Aspalathus linearis) on immobilization-induced oxidative stress in rat brain

Exposure to chronic psychological stress may be related to increased reactive oxygen species (ROS) or free radicals, and thus, long-term exposure to high levels of oxidative stress may cause the accumulation of oxidative damage and eventually lead to many neurodegenerative diseases. Compared with other organs, the brain appears especially susceptible to excessive oxidative stress due to its high demand for oxygen. In the case of excessive ROS production, endogenous defense mechanisms against ROS may not be sufficient to suppress ROS-associated oxidative damage. Dietary antioxidants have been shown to protect neurons against a variety of experimental neurodegenerative conditions. In particular, Rooibos tea might be a good source of antioxidants due to its larger proportion of polyphenolic compounds. An optimal animal model for stress should show the features of a stress response and should be able to mimic natural stress progression. However, most animal models of stress, such as cold-restraint, electric foot shock, and burn shock, usually involve physical abuse in addition to the psychological aspects of stress. Animals subjected to chronic restraint or immobilization are widely believed to be a convenient and reliable model to mimic psychological stress. Therefore, in the present study, we propose that immobilization-induced oxidative stress was significantly attenuated by treatment with Rooibos tea. This conclusion is demonstrated by Rooibos tea's ability to (i) reverse the increase in stress-related metabolites (5-HIAA and FFA), (ii) prevent lipid peroxidation (LPO), (iii) restore stress-induced protein degradation (PD), (iv) regulate glutathione metabolism (GSH and GSH/GSSG ratio), and (v) modulate changes in the activities of antioxidant enzymes (SOD and CAT).

Oxidative stress and neurodegenerative disorders

Living cells continually generate reactive oxygen species (ROS) through the respiratory chain during energetic metabolism. ROS at low or moderate concentration can play important physiological roles. However, an excessive amount of ROS under oxidative stress would be extremely deleterious. The central nervous system (CNS) is particularly vulnerable to oxidative stress due to its high oxygen consumption, weakly antioxidative systems and the terminal-differentiation characteristic of neurons. Thus, oxidative stress elicits various neurodegenerative diseases. In addition, chemotherapy could result in severe side effects on the CNS and peripheral nervous system (PNS) of cancer patients, and a growing body of evidence demonstrates the involvement of ROS in drug-induced neurotoxicities as well. Therefore, development of antioxidants as neuroprotective drugs is a potentially beneficial strategy for clinical therapy. In this review, we summarize the source, balance maintenance and physiologic functions of ROS, oxidative stress and its toxic mechanisms underlying a number of neurodegenerative diseases, and the possible involvement of ROS in chemotherapy-induced toxicity to the CNS and PNS. We ultimately assess the value for antioxidants as neuroprotective drugs and provide our comments on the unmet needs.

Downregulation of PMCA2 increases the vulnerability of midbrain neurons to mitochondrial complex I inhibition

Parkinson's disease is an age-associated disorder characterized by selective degeneration of dopaminergic neurons. The molecular mechanisms underlying the selective vulnerability of this subset of neurons are, however, not fully understood. Employing SH-SY5Y neuroblastoma cells and primary mesencephalic neurons, we here demonstrate a significant increase in cytosolic calcium after inhibition of mitochondrial complex I by means of MPP(+), which is a well-established environmental toxin-based in vitro model of Parkinson's disease. This increase in calcium is correlated with a downregulation of the neuron-specific plasma membrane Ca(2+)-ATPase isoform 2 (PMCA2). Interestingly, two other important mediators of calcium efflux, sarcoplasmic reticulum Ca(2+)-ATPase (SERCA), and Na(+)-Ca(2+)-exchanger (NCX), remained unaltered, indicating a specific role of PMCA2 in maintaining calcium homeostasis in neurons. The observed PMCA2 downregulation was accompanied by reduced levels of phosphorylated CREB protein, an intracellular signaling molecule and transcriptional regulator. In order to investigate the potential influence of PMCA2 on neuronal vulnerability, experimental downregulation of PMCA2 by means of siRNA was performed. The results demonstrate a significant impairment of cell survival under conditions of PMCA2 suppression. Hence, in our cell models increased cytosolic calcium levels as a consequence of insufficient calcium efflux lead to an increased vulnerability of neuronal cells. Moreover, overexpression of PMCA2 rendered the neurons significantly resistant to complex I inhibition. Our findings point toward a dysregulation of calcium homeostasis in Parkinson's disease and suggest a potential molecular mechanism of neurodegeneration via PMCA2.

Effect of chronic treatment with conventional and organic purple grape juices (Vitis labrusca) on rats fed with high-fat diet

Serra Gaucha is described as the most important wine region of Brazil. Regarding cultivars widespread in the Serra Gaucha, about 90 % of the area is occupied by vines of Vitis labrusca that is the most important specie used in grape juice production. The objective of this study was to investigate the antioxidant and neuroprotective effect of chronic intake of purple grape juice (organic and conventional) from Bordo variety (V. labrusca) on oxidative stress in different brain regions of rats supplemented with high-fat diet (HFD) for 3 months. A total of 40 male rats were randomly divided into 4 groups. Group 1 received a standard diet and water, group 2 HFD and water, group 3 HFD and conventional grape juice (CGJ), and group 4 HFD and organic grape juice (OGJ). All groups had free access to food and drink and after 3 months of treatment the rats were euthanized by decapitation and the cerebral cortex, hippocampus and cerebellum isolated and homogenized on ice for oxidative stress analysis. We observed that the consumption of calories in HFD and control groups, were higher than the groups supplemented with HFD and grape juices and that HFD diet group gain more weight than the other animals. Our results also demonstrated that HDF enhanced lipid peroxidation (TBARS) and protein damage (carbonyl) in cerebral cortex and hippocampus, reduced the non-enzymatic antioxidants defenses (sulfhydryl) in cerebral cortex and cerebellum, reduced catalase and superoxide dismutase activities in all brain tissues and enhanced nitric oxide production in all cerebral tissues. CGJ and OGJ were able to ameliorate these oxidative alterations, being OGJ more effective in this protection. Therefore, grape juices could be useful in the treatment of some neurodegenerative diseases associated with oxidative damage.

Neural precursor cells cultured at physiologically relevant oxygen tensions have a survival advantage following transplantation

Traditionally, in vitro stem cell systems have used oxygen tensions that are far removed from the in vivo situation. This is particularly true for the central nervous system, where oxygen (O2) levels range from 8% at the pia to 0.5% in the midbrain, whereas cells are usually cultured in a 20% O2 environment. Cell transplantation strategies therefore typically introduce a stress challenge at the time of transplantation as the cells are switched from 20% to 3% O2 (the average in adult organs). We have modeled the oxygen stress that occurs during transplantation, demonstrating that in vitro transfer of neonatal rat cortical neural precursor cells (NPCs) from a 20% to a 3% O2 environment results in significant cell death, whereas maintenance at 3% O2 is protective. This survival benefit translates to the in vivo environment, where culture of NPCs at 3% rather than 20% O2 approximately doubles survival in the immediate post-transplantation phase. Furthermore, NPC fate is affected by culture at low, physiological O2 tensions (3%), with particularly marked effects on the oligodendrocyte lineage, both in vitro and in vivo. We propose that careful consideration of physiological oxygen environments, and particularly changes in oxygen tension, has relevance for the practical approaches to cellular therapies.

Selenium homeostasis and antioxidant selenoproteins in brain: implications for disorders in the central nervous system

The essential trace element selenium, as selenocysteine, is incorporated into antioxidant selenoproteins such as glutathione peroxidases (GPx), thioredoxin reductases (TrxR) and selenoprotein P (Sepp1). Although comparatively low in selenium content, the brain exhibits high priority for selenium supply and retention under conditions of dietary selenium deficiency. Liver-derived Sepp1 is the major transport protein in plasma to supply the brain with selenium, serving as a "survival factor" for neurons in culture. Sepp1 expression has also been detected within the brain. Presumably, astrocytes secrete Sepp1, which is subsequently taken up by neurons via the apolipoprotein E receptor 2 (ApoER2). Knock-out of Sepp1 or ApoER2 as well as neuron-specific ablation of selenoprotein biosynthesis results in neurological dysfunction in mice. Astrocytes, generally less vulnerable to oxidative stress than neurons, are capable of up-regulating the expression of antioxidant selenoproteins upon brain injury. Occurrence of neurological disorders has been reported occasionally in patients with inadequate nutritional selenium supply or a mutation in the gene encoding selenocysteine synthase, one of the enzymes involved in selenoprotein biosynthesis. In three large trials carried out among elderly persons, a low selenium status was associated with faster decline in cognitive functions and poor performance in tests assessing coordination and motor speed. Future research is required to better understand the role of selenium and selenoproteins in brain diseases including hepatic encephalopathy.

Oxidative stress, cancer, and sleep deprivation: is there a logical link in this association?

INTRODUCTION

Sleep disorders are associated with various human pathologies and interfere with biological processes essential for health and quality of life. On the other hand, cancer is one of the most common diseases worldwide with an average of 1,500 deaths per day in the USA. Is there a factor common to both sleep disorders and cancer that serves to link these conditions?

DISCUSSION

It is a normal process for cellular metabolism to produce reactive oxidant series (ROS). However, when the production of ROS overcomes the antioxidant capacity of the cell to eliminate these products, the resulting state is called oxidative stress. Oxidative DNA damage may participate in ROS-induced carcinogenesis. Moreover, ROS are also produced in the sleep deprivation process. The aim of this article is to review pathways and mechanisms that may point to oxidative stress as a link between sleep deprivation and cancer.