Oxidative damage and cognitive dysfunction: antioxidant treatments to promote healthy brain aging

Effect of chewing hard material on boosting brain antioxidant levels and enhancing cognitive function

Introduction

Chewing has been reported to enhance cognitive function through the increase in cerebral blood flow. However, the mechanisms linking cerebral blood flow increase to metabolic changes in the brain affecting cognition remain unclear. We hypothesized that glutathione (GSH) plays a pivotal role in these mechanisms. Therefore, this study aimed to investigate changes in brain GSH levels following chewing and their association with cognitive function in healthy young adults.

Methods

A total of 52 university students were recruited, and the Korean version of the Repeatable Battery for the Assessment of Neuropsychological Status was used for the neurocognitive evaluations. Brain GSH levels following chewing gum or wood blocks were measured using MEscher-GArwood Point RESolved Spectroscopy (MEGA-PRESS) sequence, and their relevance to neurocognitive evaluation results was investigated.

Results

Chewing significantly increased brain GSH concentration, particularly in the wood-chewing group compared to the gum-chewing group, as observed in the anterior cingulate cortex. Furthermore, the rise in GSH concentration in the wood-chewing group was positively correlated with memory function.

Conclusion

Chewing moderately hard material elevates brain antioxidant levels such as GSH, potentially influencing cognitive function.

Identification and Validation of Oxidative Stress-Related Hub Genes in Parkinson's Disease

Accumulating evidence suggests that oxidative stress plays a crucial role in the pathogenesis of Parkinson's disease (PD). The aims of this study were to identify oxidative stress-related hub genes, validate them through the construction of a diagnostic model, explore their interactions with miRNAs and transcription factors (TFs) and predict potential drug targets. Differentially expressed genes (DEGs) in the substantia nigra of PD patients were identified by analyzing a combination of datasets selected from the GEO database, including GSE7621, GSE20141, GSE49036, and GSE20163. The candidate genes associated with oxidative stress were screened by determining the overlap among the DEGs, oxidative stress-related genes (OSGs) and genes in key modules with the highest cor values identified via weighted gene coexpression network analysis (WGCNA). The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were used to perform functional enrichment analysis of these candidate genes. The hub genes were identified via protein-protein interaction (PPI) analysis, and receiver operating characteristic (ROC) curves were constructed to assess the diagnostic value of each hub gene. Then, a diagnostic model was constructed via least absolute shrinkage and selection operator (LASSO) regression with the hub genes identified above, and the model was further validated in external validation datasets (GSE20292 and GSE20164). Gene-miRNA and gene-TF regulatory networks were predicted via the miRNet database, whereas candidate drugs were predicted via the Drug-Gene Interaction database. After analysis of the intersection of the 7975 DEGs, 434 OSGs, and 3582 genes identified through WGCNA, 76 candidate genes were identified. A total of 9 hub genes (JUN, KEAP1, SRC, GPX5, MMP9, TXN, MAPK3, GPX2, and IL1A) were identified via PPI and ROC curve analyses. A diagnostic model with the ability to reliably predict PD on the basis of the identified hub genes (AUC = 0.925) was constructed. Further analysis of these 9 genes revealed 64 targeted miRNAs, 35 TFs in regulatory networks and 86 potential therapeutic agents. Nine hub genes related to oxidative stress in the pathogenesis of PD were identified. These genes show strong diagnostic performance and could serve as therapeutic targets. These findings might facilitate the development of promising candidate biomarkers and potential disease-modifying therapies for PD.

Astaxanthin Rescues Memory Impairments in Rats with Vascular Dementia by Protecting Against Neuronal Death in the Hippocampus

Vascular dementia (VaD) is a cognitive disorder characterized by a decline in cognitive function resulting from cerebrovascular disease. The hippocampus is particularly susceptible to ischemic insults, leading to memory deficits in VaD. Astaxanthin (AST) has shown potential therapeutic effects in neurodegenerative diseases. However, the mechanisms underlying its protective effects in VaD and against hippocampal neuronal death remain unclear. In this study, We used the bilateral common carotid artery occlusion (BCCAO) method to establish a chronic cerebral hypoperfusion (CCH) rat model of VaD and administered a gastric infusion of AST at 25 mg/kg per day for 4 weeks to explore its therapeutic effects. Memory impairments were assessed using Y-maze and Morris water maze tests. We also performed biochemical analyses to evaluate levels of hippocampal neuronal death and apoptosis-related proteins, as well as the impact of astaxanthin on the PI3K/Akt/mTOR pathway and oxidative stress. Our results demonstrated that AST significantly rescued memory impairments in VaD rats. Furthermore, astaxanthin treatment protected against hippocampal neuronal death and attenuated apoptosis. We also observed that AST modulated the PI3K/Akt/mTOR pathway, suggesting its involvement in promoting neuronal survival and synaptic plasticity. Additionally, AST exhibited antioxidant properties, mitigating oxidative stress in the hippocampus. These findings provide valuable insights into the potential therapeutic effects of AST in VaD. By elucidating the mechanisms underlying the actions of AST, this study highlights the importance of protecting hippocampal neurons and suggests potential targets for intervention in VaD. There are still some unanswered questions include long-term effects and optimal dosage of the use in human. Further research is warranted to fully understand the therapeutic potential of AST and its application in the clinical treatment of VaD.

The effects of hydrolyzed protein on macronutrient digestibility, fecal metabolites and microbiota, oxidative stress and inflammatory biomarkers, and skin and coat quality in adult dogs

Research on protein hydrolysates has observed various properties and functionalities on ingredients depending on the type of hydrolysate. The objective of this study was to evaluate the effects of hydrolyzed chicken protein that was incorporated into diets on digestibility, gut health, skin and coat health, oxidative stress, and intestinal inflammation markers in healthy adult dogs. Five complete and balanced diets were manufactured: (1) CONd: 25% chicken meal diet; (2) 5% CLHd: 5% chicken liver and heart hydrolysate plus 20% chicken meal diet; (3) CLHd: 25% chicken liver and heart hydrolysate diet; (4) 5% CHd: 5% chicken hydrolysate plus 20% chicken meal diet; (5) CHd: 25% chicken hydrolysate diet. A replicated 5 × 5 Latin square design was used which included 10 neutered adult Beagles. Each of the 5 periods consisted of a 7-d washout time and a 28-d treatment period. All diets were well accepted by the dogs. Fecal butyrate concentration was higher while fecal isovalerate and total phenol/indole were lower in dogs fed CLHd than CONd (P < 0.05). Dogs fed CHd had higher fecal immunoglobulin A concentration when compared with CLHd (P < 0.05); however, both groups were comparable to the CONd. There was no difference among groups in serum cytokine concentrations, serum oxidative stress biomarkers, or skin and coat health analyses (P > 0.05). Fecal microbiota was shifted by CLHd with higher abundance in Ruminococcus gauvreauii group as well as lower Clostridium sensu stricto 1, Sutterella, Fusobacterium, and Bacteroides when compared with CONd (P < 0.05). There was also a difference in beta diversity of fecal microbiota between CLHd and CHd (P < 0.05). In conclusion, chicken protein hydrolysate could be incorporated into canine extruded diets as a comparable source of protein to traditional chicken meal. The test chicken protein hydrolysates showed the potential to support gut health by modulating immune response and microbiota; however, functional properties of protein hydrolysates are dependent on inclusion level and source.

Investigating Owner Use of Dietary Supplements in Dogs with Canine Cognitive Dysfunction

Canine cognitive dysfunction (CCD) is becoming increasingly recognized in veterinary medicine, as dogs live longer and with CCD being highly prevalent among the elderly dog population. Various studies have shown that diet and dietary supplementation can positively influence the clinical signs of CCD, especially if given at an early stage. The aim of this study was to investigate owner use of dietary supplements (DSs) in dogs with age-related behavioral changes. An observational study based on an online questionnaire for owners of dogs with age-related behavioral changes was performed. Out of a total of 394 owners who completed the survey, after noticing age-related behavioral changes, over half of the dogs received DSs (54%), whereas only 8% reported changing their dog's base diet. The most used DS was fish oil (48%). The use of DSs should be discussed with and monitored by veterinary surgeons since many geriatric patients have multi-morbidities, may have specific nutritional requirements and receive multi-faceted medications.

A Novel NOX Inhibitor Alleviates Parkinson's Disease Pathology in PFF-Injected Mice

Oxidative stress-mediated damage is often a downstream result of Parkinson's disease (PD), which is marked by sharp decline in dopaminergic neurons within the nigrostriatal regions of the brain, accounting for the symptomatic motor deficits in patients. Regulating the level of oxidative stress may present a beneficial approach in preventing PD pathology. Here, we assessed the efficacy of a nicotinamide adenine phosphate (NADPH) oxidase (NOX) inhibitor, an exogenous reactive oxygen species (ROS) regulator synthesized by Aptabio therapeutics with the specificity to NOX-1, 2 and 4. Utilizing N27 rat dopaminergic cells and C57Bl/6 mice, we confirmed that the exposures of alpha-synuclein preformed fibrils (PFF) induced protein aggregation, a hallmark in PD pathology. In vitro assessment of the novel compound revealed an increase in cell viability and decreases in cytotoxicity, ROS, and protein aggregation (Thioflavin-T stain) against PFF exposure at the optimal concentration of 10 nM. Concomitantly, the oral treatment alleviated motor-deficits in behavioral tests, such as hindlimb clasping, rotarod, pole, nesting and grooming test, via reducing protein aggregation, based on rescued dopaminergic neuronal loss. The suppression of NOX-1, 2 and 4 within the striatum and ventral midbrain regions including Substantia Nigra compacta (SNc) contributed to neuroprotective/recovery effects, making it a potential therapeutic option for PD.

Nigella sativa Oil Improves Motor Skill Learning of Albino Mice: In Vivo and In Silico Investigations

Experimental evidences demonstrated that Nigella sativa oil (NSO) can restore neuronal integrities and processes by increasing the neuronal density, decreasing apoptosis, preventing inflammatory processes, and improving the neurogenic cells in the hippocampus. This refurbishment enhances the learning process and memory. The antioxidant defense mechanism of NSO slows down the process of neurodegeneration and motor deficit. The present study aimed to investigate the effects of NSO on motor skill learning using the single pellet reaching task method on Swiss albino mice, followed by in silico studies. Mice (total of 16) were randomly divided into the control group and treatment group (n = 8). The treatment group received 1 ml/kg b.w. NSO orally once daily for 7 days, and a control group received 1 ml/kg normal saline instead of NSO in a similar manner. The average success rate due to ingestion of NSO in the treatment group mice increased significantly (P < 0.05) compared to controlled mice. Molecular docking analysis revealed that thymoquinone, carvacrol, thymohydroquinone, p-cymene, and t-anethole have binding affinities for the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R) that ranges from (-5.1 to -6.2) kcal/mol, which is comparable to the reference ligand glutamic acid binding affinity with AMPA-R (-6.6 kcal/mol). Thymoquinone and carvacrol formed hydrogen bonds with AMPA receptor at TYR61, SER142, and SER143 residues, comparable to the binding affinity of glutamic acid. ADMET analysis reported that all the compounds have higher bioavailability (>90%) and can cross the BBB easily (logBB> 0.3). Based on our experimental data and in silico report, we concluded that the enhanced motor skill learning effects of NSO are due to presence of potent antioxidants-thymoquinone and carvacrol-which might serve as AMPA receptor agonists. These phytoconstituents may play role in synaptic strengthening and promote experience-dependent motor skill learning.

Characterization and anti-aging effects of polysaccharide from Gomphus clavatus Gray

In this study, a highly branched polysaccharide (GPF, 112.0 kDa) was isolated and purified from Gomphus clavatus Gray fruiting bodies. GPF was primarily composed of mannose, galactose, arabinose, xylose, and glucose at a molar ratio of 3.2:1.9:1.6:1.2:1.0. GPF was a highly branched heteropolysaccharide composed of 13 glucosidic bonds, with a degree of branching (DB) of 48.85 %. GPF exhibited anti-aging activity in vivo, significantly increased antioxidant enzymes activities (SOD, CAT and GSH-Px), improved total antioxidant capability (T-AOC) and decreased MDA level in the serum and brain of d-Gal induced aging mice. Behavioral experiments showed that GPF effectively improved learning and memory deficits in d-Gal induced aging mice. Mechanistic studies indicated that GPF could activate AMPK by increasing AMPK phosphorylation and upregulating SIRT1 and PGC-1α expression. These findings suggest that GPF has significant potential as a natural candidate to slow down aging and prevent aging-related diseases.

Polyphenols and Their Impact on the Prevention of Neurodegenerative Diseases and Development

It is well known that neurodegenerative diseases' development and progression are accelerated due to oxidative stress and inflammation, which result in impairment of mitochondrial function, cellular damage, and dysfunction of DNA repair systems. The increased consumption of antioxidants can postpone the development of these disorders and improve the quality of patients' lives who have already been diagnosed with neurodegenerative diseases. Prolonging life span in developed countries contributes to an increase in the incidence ratio of chronic age-related neurodegenerative disorders, such as PD (Parkinson's disease), AD (Alzheimer's disease), or numerous forms of age-related dementias. Dietary supplementation with neuroprotective plant-derived polyphenols might be considered an important element of healthy aging. Some polyphenols improve cognition, mood, visual functions, language, and verbal memory functions. Polyphenols bioavailability differs greatly from one compound to another and is determined by solubility, degree of polymerization, conjugation, or glycosylation resulting from chemical structure. It is still unclear which polyphenols are beneficial because their potential depends on efficient transport across the BBB (blood-brain barrier), bioavailability, and stability in the CNS (central nervous system). Polyphenols improve brain functions by having a direct impact on cells and processes in the CNS. For a direct effect, polyphenolic compounds must be able to overcome the BBB and accumulate in brain tissue. In this review, the latest achievements in studies (animal models and clinical trials) on the effect of polyphenols on brain activity and function are described. The beneficial impact of plant polyphenols on the brain may be summarized by their role in increasing brain plasticity and related cognition improvement. As reversible MAO (monoamine oxidase) inhibitors, polyphenols are mood modulators and improve neuronal self-being through an increase in dopamine, serotonin, and noradrenaline amounts in the brain tissue. After analyzing the prohealth effects of various eating patterns, it was postulated that their beneficial effects result from synergistic interactions between individual dietary components. Polyphenols act on the brain endothelial cells and improve the BBB's integrity and reduce inflammation, thus protecting the brain from additional injury during stroke or autoimmune diseases. Polyphenolic compounds are capable of lowering blood pressure and improving cerebral blood flow. Many studies have revealed that a nutritional model based on increased consumption of antioxidants has the potential to ameliorate the cognitive impairment associated with neurodegenerative disorders. Randomized clinical trials have also shown that the improvement of cognitive functions resulting from the consumption of foods rich in flavonoids is independent of age and health conditions. For therapeutic use, sufficient quantities of polyphenols must cross the BBB and reach the brain tissue in active form. An important issue in the direct action of polyphenols on the CNS is not only their penetration through the BBB, but also their brain metabolism and localization. The bioavailability of polyphenols is low. The most usual oral administration also conflicts with bioavailability. The main factors that limit this process and have an effect on therapeutic efficacy are: selective permeability across BBB, gastrointestinal transformations, poor absorption, rapid hepatic and colonic metabolism, and systemic elimination. Thus, phenolic compounds have inadequate bioavailability for human applications to have any beneficial effects. In recent years, new strategies have been attempted in order to exert cognitive benefits and neuroprotective effects. Converting polyphenols into nanostructures is one of the theories proposed to enhance their bioavailability. The following nanoscale delivery systems can be used to encapsulate polyphenols: nanocapsules, nanospheres, micelles, cyclodextrins, solid lipid nanoparticles, and liposomes. It results in great expectations for the wide-scale and effective use of polyphenols in the prevention of neurodegenerative diseases. Thus far, only natural polyphenols have been studied as neuroprotectors. Perhaps some modification of the chemical structure of a given polyphenol may increase its neuroprotective activity and transportation through the BBB. However, numerous questions should be answered before developing neuroprotective medications based on plant polyphenols.

Salivary Oxytocin and Antioxidative Response to Robotic Touch in Adults with Autism Spectrum Disorder

Individuals with ASD are known to have a tendency to have tactile sensory processing issues that could be associated with their impairment as regards social communication. The alterations in tactile processing in autistic subjects are usually accompanied by hypersensitivity and other unpleasant emotions induced by tactile contact. In our study, we investigated the impact of the velocity and the force of a tactile stroke received impersonally by a custom-built robotic device. A total of 21 adults with ASD and 22 adults from a control group participated in our study. The participants' responses were assessed according to subjective scales, EEG changes, and the dynamics of saliva antioxidants and oxytocin. It was found that the oxytocin level was significantly lower in subjects with ASD but increased after tactile stimulation. However, contrary to expectations, the increase in the oxytocin level in the target group negatively correlated with the subjective pleasantness of tactile stimulation and was probably associated with a stress-induced effect. The basic levels of antioxidants did not differ between the TD and ASD groups; however, these had significantly increased in individuals with ASD by the end of the study. The EEG findings, which revealed enhanced antioxidant levels, contributed to the relief of the cognitive control during the study.

In vitro evaluation of the neuroprotective potential of Olea dioica against Aβ peptide-induced toxicity in human neuroblastoma SH-SY5Y cells

Alzheimer's disease (AD) is a type of neurodegenerative disease, associated with the hastening of ROS, acetylcholinesterase (AChE) activity, and amyloid β peptides plaques in the brain. The limitations and side effects of existing synthetic drugs incline toward natural sources. In the present communication active principles of methanolic extract of Olea dioica Roxb, leaves are explored as an antioxidant, AChE inhibitor, and anti-amyloidogenic. Furthermore, neuroprotection against the amyloid beta-peptide has been studied. The bioactive principles were identified by GC-MS and LC-MS and further subjected to antioxidant (DPPH and FRAP) and neuroprotection (AChE inhibition, ThT binding, and MTT assay, DCFH-DA and lipid peroxidation (LPO) assay using neuroblastoma (SHSY-5Y) cell lines) assays. Methanolic extract of O. dioica Roxb, leaves was found to contain polyphenols and flavonoids. In vitro assays exhibited potential antioxidant and anti-AChE (˃50%) activities. ThT binding assay indicated protection against amyloid-beta aggregation. MTT assay, Aβ1-40 (10 µM) with extract increase the cell viability (˃50%) and showed significant cytotoxicity to SHSY-5Y cells. ROS level (˃25%) significantly decreased in the Aβ1-40 (10 µM) + extract (15 and 20 μM/mL) and LPO assay (˃50%) suggesting prevention of cell damage. Results advocate that O. dioica leaves are a good source of antioxidants, anti-AChE, and anti-amyloidogenic compounds which may be further evaluated as a natural medicine for the treatment of AD.

Identification of oxidative stress-related genes differentially expressed in Alzheimer's disease and construction of a hub gene-based diagnostic model

Alzheimer's disease (AD) is the most prevalent dementia disorder globally, and there are still no effective interventions for slowing or stopping the underlying pathogenic mechanisms. There is strong evidence implicating neural oxidative stress (OS) and ensuing neuroinflammation in the progressive neurodegeneration observed in the AD brain both during and prior to symptom emergence. Thus, OS-related biomarkers may be valuable for prognosis and provide clues to therapeutic targets during the early presymptomatic phase. In the current study, we gathered brain RNA-seq data of AD patients and matched controls from the Gene Expression Omnibus (GEO) to identify differentially expressed OS-related genes (OSRGs). These OSRGs were analyzed for cellular functions using the Gene Ontology (GO) database and used to construct a weighted gene co-expression network (WGCN) and protein-protein interaction (PPI) network. Receiver operating characteristic (ROC) curves were then constructed to identify network hub genes. A diagnostic model was established based on these hub genes using Least Absolute Shrinkage and Selection Operator (LASSO) and ROC analyses. Immune-related functions were examined by assessing correlations between hub gene expression and immune cell brain infiltration scores. Further, target drugs were predicted using the Drug-Gene Interaction database, while regulatory miRNAs and transcription factors were predicted using miRNet. In total, 156 candidate genes were identified among 11046 differentially expressed genes, 7098 genes in WGCN modules, and 446 OSRGs, and 5 hub genes (MAPK9, FOXO1, BCL2, ETS1, and SP1) were identified by ROC curve analyses. These hub genes were enriched in GO annotations "Alzheimer's disease pathway," "Parkinson's Disease," "Ribosome," and "Chronic myeloid leukemia." In addition, 78 drugs were predicted to target FOXO1, SP1, MAPK9, and BCL2, including fluorouracil, cyclophosphamide, and epirubicin. A hub gene-miRNA regulatory network with 43 miRNAs and hub gene-transcription factor (TF) network with 36 TFs were also generated. These hub genes may serve as biomarkers for AD diagnosis and provide clues to novel potential treatment targets.

Folic acid protects against age-associated apoptosis and telomere attrition of neural stem cells in senescence-accelerated mouse prone 8

Folic acid (FA) could improve cognitive performance and attenuate brain cell injury in the aging brain; FA supplementation is also associated with inhibiting neural stem cell (NSC) apoptosis. However, its role in age-associated telomere attrition remains unclear. We hypothesized that FA supplementation attenuates age-associated apoptosis of NSCs in mice via alleviating telomere attrition in senescence-accelerated mouse prone 8 (SAMP8). In this study, 4-month-old male SAMP8 mice were assigned equal numbers to four different diet groups (n = 15). Fifteen age-matched senescence-accelerated mouse resistant 1 mice, fed with the FA-normal diet, were used as the standard aging control group. After FA treatment for 6 months, all mice were sacrificed. NSC apoptosis, proliferation, oxidative damage, and telomere length were evaluated by immunofluorescence and Q-fluorescent in situ hybridization. The results showed that FA supplementation inhibited age-associated NSC apoptosis and prevented telomere attrition in the cerebral cortex of SAMP8 mice. Importantly, this effect might be explained by the decreased levels of oxidative damage. In conclusion, we demonstrate it may be one of the mechanisms by which FA inhibits age-associated NSC apoptosis by alleviating telomere length shortening.

Mechanistic Insights, Treatment Paradigms, and Clinical Progress in Neurological Disorders: Current and Future Prospects

Neurodegenerative diseases (NDs) are a major cause of disability and are related to brain development. The neurological signs of brain lesions can vary from mild clinical shortfalls to more delicate and severe neurological/behavioral symptoms and learning disabilities, which are progressive. In this paper, we have tried to summarize a collective view of various NDs and their possible therapeutic outcomes. These diseases often occur as a consequence of the misfolding of proteins post-translation, as well as the dysfunctional trafficking of proteins. In the treatment of neurological disorders, a challenging hurdle to cross regarding drug delivery is the blood-brain barrier (BBB). The BBB plays a unique role in maintaining the homeostasis of the central nervous system (CNS) by exchanging components between the circulations and shielding the brain from neurotoxic pathogens and detrimental compounds. Here, we outline the current knowledge about BBB deterioration in the evolving brain, its origin, and therapeutic interventions. Additionally, we summarize the physiological scenarios of the BBB and its role in various cerebrovascular diseases. Overall, this information provides a detailed account of BBB functioning and the development of relevant treatments for neurological disorders. This paper will definitely help readers working in the field of neurological scientific communities.

Adherence to a Mediterranean Diet is associated with physical and cognitive health: A cross-sectional analysis of community-dwelling older Australians

Poor cognitive function is associated with reduced functional independence, risk of institutionalization and reduced health-related quality of life. The ability to independently perform instrumental activities of daily living (iADLs) is compromised in patients with mild cognitive impairment (MCI) or dementia. Emerging evidence suggests that adherence to a Mediterranean diet (MedDiet), may play an important protective role against cognitive decline and dementia risk, whilst preserving functional status. This cross-sectional study aimed to explore the independent associations between MedDiet adherence, cognitive risk, and functional status in community-dwelling older adults living in Australia. MedDiet adherence was assessed using the Mediterranean Diet Adherence Screener (MEDAS); a modified Lawton's iADL scale was used for the assessment of functional status and risk of cognitive impairment was assessed using the AD8 dementia screening intervention. A total of n = 294 participants were included in the final analyses (70.4 ± 6.2 years; Females, n = 201; Males, n = 91; n = 2 unspecified). Adherence to a MedDiet was positively associated with functional ability (β = 0.172; CI: 0.022, 0.132; P = 0.006) independent of age, gender, Body Mass Index (BMI), smoking status, sleep duration, physical activity duration, diabetes status, and level of education. Furthermore, MedDiet adherence was inversely associated with cognitive risk (β = -0.134; CI: -0.198, -0.007; P = 0.035) independent of all covariates. However, our sensitivity analyses further showed that adherence to a MedDiet was not associated with cognitive risk in older adults free from cognitive impairment. We showed that adherence to a MedDiet is associated with healthy physical and cognitive aging. Nevertheless, exploration of these findings in larger cohorts, using longitudinal analyses and controlling for important confounders to ascertain the direction of the relationship is warranted.

Oxidative stress-mediated memory impairment during aging and its therapeutic intervention by natural bioactive compounds

Aging and associated neurodegenerative diseases are accompanied by the decline of several brain functions including cognitive abilities. Progressive deleterious changes at biochemical and physiological levels lead to the generation of oxidative stress, accumulation of protein aggregates, mitochondrial dysfunctions, loss of synaptic connections, and ultimately neurodegeneration and cognitive decline during aging. Oxidative stress that arises due to an imbalance between the rates of production and elimination of free radicles is the key factor for age-associated neurodegeneration and cognitive decline. Due to high energy demand, the brain is more susceptible to free radicals-mediated damages as they oxidize lipids, proteins, and nucleic acids, thereby causing an imbalance in the homeostasis of the aging brain. Animal, as well as human subject studies, showed that with almost no or few side effects, dietary interventions and plant-derived bioactive compounds could be beneficial to recovering the memory or delaying the onset of memory impairment. As the plant-derived bioactive compounds have antioxidative properties, several of them were used to recover the oxidative stress-mediated changes in the aging brain. In the present article, we review different aspects of oxidative stress-mediated cognitive change during aging and its therapeutic intervention by natural bioactive compounds.

A new mitochondrial probe combining pyrene and a triphenylphosphonium salt for cellular oxygen and free radical detection via fluorescence lifetime measurements

To improve and diversify the quantification of reactive oxygen species (ROS) in mitochondria of single cells, we connected pyrene derivatives (PB) to a triphenylphosphonium salt (TPP⁺) as a mitochondrial vector forming PB-TPP⁺ probes. Two pyrene isomers with the n-butyltriphenylphosphonium moieties attached at their 1- or 2- positions were synthesized and characterized. Using the long fluorescence lifetime of pyrene, it was possible to monitor the variation of cellular free radicals and oxygen and to follow the reversibility of both quenchers in real-time. We compared the behavior of these new probes to the previously published pyrene-probes, functionalized by a mitochondrial-penetrating peptide, allowing their transfer to the mitochondria (Mito-PB) or to the cytosolic membrane for pyrene butyric acid (PBA). The high cellular uptake of the new probes allows cells to be loaded with an initial concentration 40 times lower than that for Mito-PB probes, without inducing perturbations in cell growth. The variation in free radicals and oxygen levels was monitored within cells under different stress conditions through the fluorescence lifetime of the new TPP⁺-based probes giving comparable results to those obtained for MPP-based probes. However, at a loading concentration as low as 25 nM, our technique allows the detection of increased production of free radicals in the mitochondria in the presence of the TPP⁺ vector, a warning to the user of this well-known vector.

Antioxidant Potential, DNA Damage, Inflammation, Glycemic Control and Lipid Metabolism Alteration: A Mediation Analysis of Islamic Sunnah Intermittent Fasting on Cognitive Function among Older Adults with Mild Cognitive Impairment

OBJECTIVES

This study aimed to determine the relationship between oxidative stress, DNA damage, inflammation, and metabolic biomarkers as the mediating factor between Islamic Sunnah intermittent fasting (IF) practice and cognitive function among older adults with mild cognitive impairment (MCI).

DESIGN

This study was a 36 months prospective cohort study.

SETTING

Community-dwelling older participants recruited through a stratified random sampling method from four states representing Malaysia's central, north-west, northeast and southern regions.

PARTICIPANTS

Ninety-nine Malay Muslim older adults (n= 99) aged 60 and above with MCI and no known critical illnesses were included in the current analysis. The participants were divided into regularly practicing IF (r-IF), irregularly practicing IF (i-IF) and not practicing IF (n-IF) groups.

MEASUREMENTS

Fasting venous blood was collected and used to determine the levels of oxidative stress, DNA damage, inflammatory and metabolic biomarkers. Mini-Mental State Examination, Montreal Cognitive Assessment, Rey Auditory Verbal Learning Test, Digit Span and Digit symbol were used to evaluate the cognitive function. Then, the mediation analysis was conducted using a multistep regression model to determine the mediating role of various biomarkers between IF practice and cognitive function.

RESULTS

When comparing the r-IF and n-IF groups, higher SOD activity, lower DNA damage (percentage of DNA in tail), lower CRP levels and higher HDL-cholesterol levels established partial mediation while lower insulin levels established complete mediation between IF practice and better cognitive function. Meanwhile, when comparing the r-IF and i-IF groups, higher SOD activity and lower CRP levels completely mediated the effects of IF practice on better cognitive function.

CONCLUSION

It can be concluded that changes in antioxidant function, DNA damage, inflammation and a limited set of metabolic biomarkers (insulin and HDL cholesterol) may mediate improvements in cognitive function among older participants with MCI who practice Islamic Sunnah IF.

A Novel NOX Inhibitor Treatment Attenuates Parkinson's Disease-Related Pathology in Mouse Models

Parkinson's disease (PD) is a progressive neurodegenerative motor disorder without an available therapeutic to halt the formation of Lewy bodies for preventing dopaminergic neuronal loss in the nigrostriatal pathway. Since oxidative-stress-mediated damage has been commonly reported as one of the main pathological mechanisms in PD, we assessed the efficacy of a novel NOX inhibitor from AptaBio Therapeutics (C-6) in dopaminergic cells and PD mouse models. The compound reduced the cytotoxicity and enhanced the cell viability at various concentrations against MPP+ and α-synuclein preformed fibrils (PFFs). Further, the levels of ROS and protein aggregation were significantly reduced at the optimal concentration (1 µM). Using two different mouse models, we gavaged C-6 at two different doses to the PD sign-displaying transgenic mice for 2 weeks and stereotaxically PFF-injected mice for 5 weeks. Our results demonstrated that both C-6-treated mouse models showed alleviated motor deficits in pole test, hindlimb clasping, crossbeam, rotarod, grooming, and nesting analyses. We also confirmed that the compound treatment reduced the levels of protein aggregation, along with phosphorylated-α-synuclein, in the striatum and ventral midbrain and further dopaminergic neuronal loss. Taken together, our results strongly suggest that NOX inhibition can be a potential therapeutic target for PD.

Recent Progress on the Salt Tolerance Mechanisms and Application of Tamarisk

Salinized soil is a major environmental stress affecting plant growth and development. Excessive salt in the soil inhibits the growth of most plants and even threatens their survival. Halophytes are plants that can grow and develop normally on saline-alkali soil due to salt tolerance mechanisms that emerged during evolution. For this reason, halophytes are used as pioneer plants for improving and utilizing saline land. Tamarisk, a family of woody halophytes, is highly salt tolerant and has high economic value. Understanding the mechanisms of salt tolerance in tamarisk and identifying the key genes involved are important for improving saline land and increasing the salt tolerance of crops. Here, we review recent advances in our understanding of the salt tolerance mechanisms of tamarisk and the economic and medicinal value of this halophyte.

Role of Creatine Supplementation in Conditions Involving Mitochondrial Dysfunction: A Narrative Review

Creatine monohydrate (CrM) is one of the most widely used nutritional supplements among active individuals and athletes to improve high-intensity exercise performance and training adaptations. However, research suggests that CrM supplementation may also serve as a therapeutic tool in the management of some chronic and traumatic diseases. Creatine supplementation has been reported to improve high-energy phosphate availability as well as have antioxidative, neuroprotective, anti-lactatic, and calcium-homoeostatic effects. These characteristics may have a direct impact on mitochondrion's survival and health particularly during stressful conditions such as ischemia and injury. This narrative review discusses current scientific evidence for use or supplemental CrM as a therapeutic agent during conditions associated with mitochondrial dysfunction. Based on this analysis, it appears that CrM supplementation may have a role in improving cellular bioenergetics in several mitochondrial dysfunction-related diseases, ischemic conditions, and injury pathology and thereby could provide therapeutic benefit in the management of these conditions. However, larger clinical trials are needed to explore these potential therapeutic applications before definitive conclusions can be drawn.

Comparing the Effects of Rosemary Extract and Treadmill Exercise on the Hippocampal Function and Antioxidant Capacity in Old Rats

Introduction:

A sequence of time-dependent changes can affect the brain’s functional capacity.

This study aimed at investigating the effects of Forced Aerobic Exercise (FAE) versus the Rosemary Extract (RE) on the learning abilities and oxidative stress modulation in rats.

Methods:

Young and old rats received daily FAE and RE for 3 months. Using the Passive Avoidance (PA) test, we evaluated the learning and memory of the rats by Step-Through Latency (STL) score. We measured the Superoxide Dismutase (SOD), Glutathione Peroxidase (GPx), Catalase (CATA), Malondialdehyde (MDA) enzymes levels, and Total Antioxidant Capacity (TAC) in the hippocampus

Results:

FAE could significantly increase the STL score (P<0.001) among old rats similar to the rosemary extract consumption. The SOD, GPx, and CATA enzyme activities and the level of TAC significantly increased by the treatments (exercise: P<0.001 for SOD and TAC and P<0.05 for CATA, exercise/rosemary: P<0.001 for all enzymes, and rosemary: P<0.01 for SOD and TAC). Furthermore, the MDA level significantly decreased by the treatments (exercise and exercise/rosemary: P<0.001, rosemary: P<0.01). The partial Pearson test revealed the significant positive correlations between the score of STL (day 2) with the SOD (P<0.01) and TAC (P<0.05) levels and negative correlations between the MDA level and STL score in both days (P<0.05 for the first day and P<0.001 for the second day).

Conclusion:

Similar to the rosemary extract, FAE could increase the working memory and antioxidants activity in old rats in 3 months.

The interplay among oxidative stress, brain insulin resistance and AMPK dysfunction contribute to neurodegeneration in type 2 diabetes and Alzheimer disease

Alzheimer's disease (AD) is the most common form of dementia in the elderly followed by vascular dementia. In addition to clinically diagnosed dementia, cognitive dysfunction has been reported in diabetic patients. Recent studies are now beginning to recognize type 2 diabetes mellitus (T2DM), characterized by chronic hyperglycemia and insulin resistance, as a risk factor for AD and other cognitive disorders. While studies on insulin action have remained traditionally in the domain of peripheral tissues, the detrimental effects of insulin resistance in the central nervous system on cognitive dysfunction are increasingly being reported in recent clinical and preclinical studies. Brain functions require continuous supply of glucose and oxygen and a tight regulation of metabolic processes. Loss of this metabolic regulation has been proposed to be a contributor to memory dysfunction associated with neurodegeneration. Within the above scenario, this review will focus on the interplay among oxidative stress (OS), insulin resistance and AMPK dysfunctions in the brain by highlighting how these neurotoxic events contribute to neurodegeneration. We provide an overview on the detrimental effects of OS on proteins regulating insulin signaling and how these alterations impact cell metabolic dysfunctions through AMPK dysregulation. Such processes, we assert, are critically involved in the molecular pathways that underlie AD.

NADPH Oxidase: a Possible Therapeutic Target for Cognitive Impairment in Experimental Cerebral Malaria

Long-term cognitive impairment associated with seizure-induced hippocampal damage is the key feature of cerebral malaria (CM) pathogenesis. One-fourth of child survivors of CM suffer from long-lasting neurological deficits and behavioral anomalies. However, mechanisms on hippocampal dysfunction are unclear. In this study, we elucidated whether gp91^phox isoform of nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) (a potent marker of oxidative stress) mediates hippocampal neuronal abnormalities and cognitive dysfunction in experimental CM (ECM). Mice symptomatic to CM were rescue treated with artemether monotherapy (ARM) and in combination with apocynin (ARM + APO) adjunctive based on scores of Rapid Murine Come behavior Scale (RMCBS). After a 30-day survivability period, we performed Barnes maze, T-maze, and novel object recognition cognitive tests to evaluate working and reference memory in all the experimental groups except CM. Sensorimotor tests were conducted in all the cohorts to assess motor coordination. We performed Golgi-Cox staining to illustrate cornu ammonis-1 (CA1) pyramidal neuronal morphology and study overall hippocampal neuronal density changes. Further, expression of NOX2, NeuN (neuronal marker) in hippocampal CA1 and dentate gyrus was determined using double immunofluorescence experiments in all the experimental groups. Mice administered with ARM monotherapy and APO adjunctive treatment exhibited similar survivability. The latter showed better locomotor and cognitive functions, reduced ROS levels, and hippocampal NOX2 immunoreactivity in ECM. Our results show a substantial increase in hippocampal NeuN immunoreactivity and dendritic arborization in ARM + APO cohorts compared to ARM-treated brain samples. Overall, our study suggests that overexpression of NOX2 could result in loss of hippocampal neuronal density and dendritic spines of CA1 neurons affecting the spatial working and reference memory during ECM. Notably, ARM + APO adjunctive therapy reversed the altered neuronal morphology and oxidative damage in hippocampal neurons restoring long-term cognitive functions after CM.

Unusual Bioactive Compounds with Antioxidant Properties in Adjuvant Therapy Supporting Cognition Impairment in Age-Related Neurodegenerative Disorders

Cognitive function decline is strictly related to age, resulting in the loss of the ability to perform daily behaviors and is a fundamental clinical neurodegeneration symptom. It has been proven that an adequate diet, comprehensive nutrition, and a healthy lifestyle may significantly inhibit neurodegenerative processes, improving cognitive functions. Therefore, intensive research has been conducted on cognitive-enhancing treatment for many years, especially with substances of natural origin. There are several intervention programs aimed at improving cognitive functions in elderly adults. Cognitive functions depend on body weight, food consumed daily, the quality of the intestinal microflora, and the supplements used. The effectiveness in the prevention of dementia is particularly high before the onset of the first symptoms. The impact of diet and nutrition on age-associated cognitive decline is becoming a growing field as a vital factor that may be easily modified, and the effects may be observed on an ongoing basis. The paper presents a review of the latest preclinical and clinical studies on the influence of natural antioxidants on cognitive functions, with particular emphasis on neurodegenerative diseases. Nevertheless, despite the promising research results in animal models, the clinical application of natural compounds will only be possible after solving a few challenges.

Synergistic Neuroprotective Effects of a Natural Product Mixture against AD Hallmarks and Cognitive Decline in Caenorhabditis elegans and an SAMP8 Mice Model

The study of different natural products can provide a wealth of bioactive compounds, and more interestingly, their combination can exert a new strategy for several neurodegenerative diseases with major public health importance, such as Alzheimer’s disease (AD). Here, we investigated the synergistic neuroprotective effects of a mixed extract composed of docosahexaenoic acid, Ginkgo biloba, D-pinitol, and ursolic acid in several transgenic Caenorhabditis elegans (C. elegans) and a senescence-accelerated prone mice 8 (SAMP8) model. First, we found a significantly higher survival percentage in the C. elegans group treated with the natural product mixture compared to the single extract-treated groups. Likewise, we found a significantly increased lifespan in group of C. elegans treated with the natural product mixture compared to the other groups, suggesting synergistic effects. Remarkably, we determined a significant reduction in Aβ plaque accumulation in the group of C. elegans treated with the natural product mixture compared to the other groups, confirming synergy. Finally, we demonstrated better cognitive performance in the group treated with the natural product mixture in both AD models (neuronal Aβ C. elegans strain CL2355 and the SAMP8 mice model), confirming the molecular results and unraveling the synergist effects of this combination. Therefore, our results proved the potential of this new natural product mixture for AD therapeutic strategies.

High fat diet and its effects on cognitive health: alterations of neuronal and vascular components of brain

It has been well recognized that intake of diets rich in saturated fats could result in development of metabolic disorders such as type 2 diabetes mellitus, obesity and cardiovascular diseases. Recent studies have suggested that intake of high fat diet (HFD) is also associated with cognitive dysfunction. Various preclinical studies have demonstrated the impact of short and long term HFD feeding on the biochemical and behavioural alterations. This review summarizes studies and the protocols used to assess the impacts of HFD feeding on cognitive performance in rodents. Further, it discuss the key mechanisms that are altered by HFD feeding, such as, insulin resistance, oxidative stress, neuro-inflammation, transcriptional dysregulation and loss of synaptic plasticity. Along with these, HFD feeding also alters the vascular components of brain such as loss of BBB integrity and reduced cerebral blood flow. It is highly possible that these factors are responsible for the development of cognitive deficits as a result of HFD feeding.

mTOR in Alzheimer disease and its earlier stages: Links to oxidative damage in the progression of this dementing disorder

Alzheimer's disease (AD) is the most prevalent form of dementia in the elderly population and has worldwide impact. The etiology of the disease is complex and results from the confluence of multiple mechanisms ultimately leading to neuronal loss and cognitive decline. Among risk factors, aging is the most relevant and accounts for several pathogenic events that contribute to disease-specific toxic mechanisms. Accumulating evidence linked the alterations of the mammalian target of rapamycin (mTOR), a serine/threonine protein kinase playing a key role in the regulation of protein synthesis and degradation, to age-dependent cognitive decline and pathogenesis of AD. To date, growing studies demonstrated that aberrant mTOR signaling in the brain affects several pathways involved in energy metabolism, cell growth, mitochondrial function and proteostasis. Recent advances associated alterations of the mTOR pathway with the increased oxidative stress. Disruption of all these events strongly contribute to age-related cognitive decline including AD. The current review discusses the main regulatory roles of mTOR signaling network in the brain, focusing on its role in autophagy, oxidative stress and energy metabolism. Collectively, experimental data suggest that targeting mTOR in the CNS can be a valuable strategy to prevent/slow the progression of AD.

Improving Age-Related Cognitive Decline through Dietary Interventions Targeting Mitochondrial Dysfunction

Aging is inevitable and it is one of the major contributors to cognitive decline. However, the mechanisms underlying age-related cognitive decline are still the object of extensive research. At the biological level, it is unknown how the aging brain is subjected to progressive oxidative stress and neuroinflammation which determine, among others, mitochondrial dysfunction. The link between mitochondrial dysfunction and cognitive impairment is becoming ever more clear by the presence of significant neurological disturbances in human mitochondrial diseases. Possibly, the most important lifestyle factor determining mitochondrial functioning is nutrition. Therefore, with the present work, we review the latest findings disclosing a link between nutrition, mitochondrial functioning and cognition, and pave new ways to counteract cognitive decline in late adulthood through diet.

Whole-body senescent cell clearance alleviates age-related brain inflammation and cognitive impairment in mice

Cellular senescence is characterized by an irreversible cell cycle arrest and a pro-inflammatory senescence-associated secretory phenotype (SASP), which is a major contributor to aging and age-related diseases. Clearance of senescent cells has been shown to improve brain function in mouse models of neurodegenerative diseases. However, it is still unknown whether senescent cell clearance alleviates cognitive dysfunction during the aging process. To investigate this, we first conducted single-nuclei and single-cell RNA-seq in the hippocampus from young and aged mice. We observed an age-dependent increase in p16Ink4a senescent cells, which was more pronounced in microglia and oligodendrocyte progenitor cells and characterized by a SASP. We then aged INK-ATTAC mice, in which p16Ink4a -positive senescent cells can be genetically eliminated upon treatment with the drug AP20187 and treated them either with AP20187 or with the senolytic cocktail Dasatinib and Quercetin. We observed that both strategies resulted in a decrease in p16Ink4a exclusively in the microglial population, resulting in reduced microglial activation and reduced expression of SASP factors. Importantly, both approaches significantly improved cognitive function in aged mice. Our data provide proof-of-concept for senolytic interventions' being a potential therapeutic avenue for alleviating age-associated cognitive impairment.

Astaxanthin protects cognitive function of vascular dementia

OBJECTIVE

The purpose of this study was to evaluate the effect of astaxanthin (AST) on cognition function, inflammatory response and oxidative stress in vascular dementia (VD) mice.

METHOD

VD mice model was established by left unilateral common carotid arteries occlusion (LUCCAO). Following LUCCAO, AST was intragastrically administered for 30 days. Object recognition test and morris water maze test were used to evaluate cognitive function. Hematoxylin and eosin staining was performed to observe the hippocampal neuron structure. Enzyme-linked immunosorbent assay kit and bicinchoninic acid kit were respectively adopted to measure IL-1β and IL-4 protein expression and superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in hippocampus and prefrontal cortex.

RESULTS

AST improved the discrimination ability of VD mice. The escape latency and path length of VD mice treated with AST were dramatically reduced. Besides, AST 200 mg/kg enhanced crossing platform time and the number of times crossing the platform quadrant, and alleviated the morphological impairment in VD mice. Moreover, we found that AST inhibited IL-1β expression and MDA content, whereas promoted IL-4 expression and SOD activity in a dose-dependent manner.

CONCLUSION

AST could improve cognitive impairment and hippocampal neurons in VD mice, which may be related to suppression of inflammatory response and oxidative stress.

Dietary Diversity Is Associated With Memory Status in Chinese Adults: A Prospective Study

BACKGROUND AND AIM

Subjective memory complaints are common in elderly people. Nutrition plays an important role in keeping brain health, however, the evidence on dietary diversity and subjective memory status is limited. This study aimed to investigate the effect of dietary diversity score (DDS) on memory status in Chinese adults in a prospective cohort study.

METHODS

Data of the China Health and Nutrition Survey was used in this study. A total of 4356 participants aged 50 years or older were enrolled in the analysis. DDS was calculated based on the dietary recall data collected in the wave of 2011. Information on self-report memory status (OK, good, or bad) and memory change in the past 12 months (stayed the same, improved, or deteriorated) were obtained from the wave of 2015. A memory score was calculated based on a subset of items of the Telephone Interview for Cognitive Status-modified. Multinomial logistic regression models were used to estimate the associations of DDS with memory status and memory change, and linear regression models were carried out to estimate the association between DDS and memory score.

RESULTS

In the study population, the percentages of participants who thought their memory was OK, bad, and good were 43.3, 24.3, and 32.4%, respectively. There were 1.4% of participants reported memory improvement in the past 12 months and 47.2% reported memory decline. Average memory score among participants was 12.8 ± 6.1. Compared with participants who thought their memory was OK, a higher DDS was associated with self-reported good memory (Odds Ratio [OR] 1.15, 95%CI 1.07-1.24) and inversely associated with bad memory (OR 0.82, 95%CI 0.75-0.89). In subgroup analysis, however, in participants aged 65 years and above, the association between DDS and self-reported good memory was insignificant (OR 1.09, 95%CI 0.94-1.25). Compared with participants whose memory stayed the same, higher DDS was inversely associated with memory decline (OR 0.85, 95%CI 0.80-0.91). Besides, higher DDS was associated with higher memory score (β 0.74, 95%CI 0.56-0.91).

CONCLUSION

This study revealed that higher DDS was associated with better memory status and was inversely associated with self-reported memory decline in Chinese adults.

The neuroprotective effect of curcumin against Cd-induced neurotoxicity and hippocampal neurogenesis promotion through CREB-BDNF signaling pathway

Heavy metal neurotoxicity is one of the major challenges in today's era due to the large scale and widespread mechanisation of the production. However, the causative factors responsible for neurotoxicity are neither known nor do we have the availability of therapeutic approaches to deal with it. One of the major causative agents of neurotoxicity is a non-essential transition heavy metal, Cadmium (Cd), that reaches the central nervous system (CNS) through the nasal mucosa and olfactory pathway causing adverse structural and functional effects. In this study, we explored the neuroprotective efficacy of plant derived Curcumin which is reported to have pleiotropic biological activity including anti-oxidant, anti-inflammatory, anti-apoptotic, anti-carcinogenic and anti-angiogenic effects. Four different concentrations of curcumin (20, 40, 80 and 160 mg/kg of the body weight) were used to assess the behavioural, biochemical, hippocampal proteins (BDNF, CREB, DCX and Synapsin II) and histological changes in Swiss Albino mice that were pre-treated with Cd (2.5 mg/kg). The findings showed that Cd exposure led to the behavioural impairment through oxidative stress, reduction of hippocampal neurogenesis associated proteins, and degeneration of CA3 and cortical neurons. However, treatment of different curcumin concentrations had effectively restored the behavioural changes in Cd-exposed mice through regulation of oxidative stress and up-regulation of hippocampal proteins in a dose-dependent manner. Significantly, a dose of 160 mg/kg body weight was found to be glaringly effective. From this study, we infer that curcumin reverses the adverse effects of neurotoxicity induced by Cd and promotes neurogenesis.

Oxidative Stress in DNA Repeat Expansion Disorders: A Focus on NRF2 Signaling Involvement

DNA repeat expansion disorders are a group of neuromuscular and neurodegenerative diseases that arise from the inheritance of long tracts of nucleotide repetitions, located in the regulatory region, introns, or inside the coding sequence of a gene. Although loss of protein expression and/or the gain of function of its transcribed mRNA or translated product represent the major pathogenic effect of these pathologies, mitochondrial dysfunction and imbalance in redox homeostasis are reported as common features in these disorders, deeply affecting their severity and progression. In this review, we examine the role that the redox imbalance plays in the pathological mechanisms of DNA expansion disorders and the recent advances on antioxidant treatments, particularly focusing on the expression and the activity of the transcription factor NRF2, the main cellular regulator of the antioxidant response.

Canine Models of Inherited Musculoskeletal and Neurodegenerative Diseases

Mouse models of human disease remain the bread and butter of modern biology and therapeutic discovery. Nonetheless, more often than not mouse models do not reproduce the pathophysiology of the human conditions they are designed to mimic. Naturally occurring large animal models have predominantly been found in companion animals or livestock because of their emotional or economic value to modern society and, unlike mice, often recapitulate the human disease state. In particular, numerous models have been discovered in dogs and have a fundamental role in bridging proof of concept studies in mice to human clinical trials. The present article is a review that highlights current canine models of human diseases, including Alzheimer's disease, degenerative myelopathy, neuronal ceroid lipofuscinosis, globoid cell leukodystrophy, Duchenne muscular dystrophy, mucopolysaccharidosis, and fucosidosis. The goal of the review is to discuss canine and human neurodegenerative pathophysiologic similarities, introduce the animal models, and shed light on the ability of canine models to facilitate current and future treatment trials.

Methanolic extract of Tamarix Gallica attenuates hyperhomocysteinemia induced AD-like pathology and cognitive impairments in rats

Although few drugs are available today for the management of Alzheimer’s disease (AD) and many plants and their extracts are extensively employed in animals’ studies and AD patients, yet no drug or plant extract is able to reverse AD symptoms adequately. In the present study, Tamarix gallica (TG), a naturally occurring plant known for its strong antioxidative, anti-inflammatory and anti-amyloidogenic properties, was evaluated on homocysteine (Hcy) induced AD-like pathology and cognitive impairments in rats. We found that TG attenuated Hcy-induced oxidative stress and memory deficits. TG also improved neurodegeneration and neuroinflammation by upregulating synaptic proteins such as PSD95 and synapsin 1 and downregulating inflammatory markers including CD68 and GFAP with concomitant decrease in proinflammatory mediators interlukin-1β (IL1β) and tumor necrosis factor α (TNFα). TG attenuated tau hyperphosphorylation at multiple AD-related sites through decreasing some kinases and increasing phosphatase activities. Moreover, TG rescued amyloid-β (Aβ) pathology through downregulating BACE1. Our data for the first time provide evidence that TG attenuates Hcy-induced AD-like pathological changes and cognitive impairments, making TG a promising candidate for the treatment of AD-associated pathological changes.

The role of NOX inhibitors in neurodegenerative diseases

Oxidative stress is a key player in both chronic and acute brain disease due to the higher metabolic demand of the brain. Among the producers of free radicals, NADPH-oxidase (NOX) is a major contributor to oxidative stress in neurological disorders. In the brain, the superoxide produced by NOX is mainly found in leukocytes. However, recent studies have reported that it can be found in several other cell types. NOX has been reported to regulate neuronal signaling, memory processing, and central cardiovascular homeostasis. However, overproduction of NOX can contribute to neurotoxicity, CNS degeneration, and cardiovascular disorders. Regarding the above functions, NOX has been shown to play a crucial role in chronic CNS diseases like Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's disease (HD), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS), and in acute CNS disorders such as stroke, spinal cord injury, traumatic brain injury (TBI), and related cerebrovascular diseases. NOX is a multi-subunit complex consisting of two membrane-associated and four cytosolic subunits. Thus, in recent years, inhibition of NOX activity has drawn a great deal of attention from researchers in the field of treating chronic and acute CNS disorders and preventing secondary complications. Mounting evidence has shown that NOX inhibition is neuroprotective and that inhibiting NOX in circulating immune cells can improve neurological disease conditions. This review summarizes recent studies on the therapeutic effects and pharmacological strategies regarding NOX inhibitors in chronic and acute brain diseases and focuses on the hurdles that should be overcome before their clinical implementation.

Implications of PI3K/AKT/PTEN Signaling on Superoxide Dismutases Expression and in the Pathogenesis of Alzheimer's Disease

Alzheimer’s disease is a neurodegenerative sickness, where the speed of personal disease progression differs prominently due to genetic and environmental factors such as life style. Alzheimer’s disease is described by the construction of neuronal plaques and neurofibrillary tangles composed of phosphorylated tau protein. Mitochondrial dysfunction may be a noticeable feature of Alzheimer’s disease and increased production of reactive oxygen species has long been described. Superoxide dismutases (SODs) protect from excess reactive oxygen species to form less reactive hydrogen peroxide. It is suggested that SODs can play a protective role in neurodegeneration. In addition, PI3K/AKT pathway has been shown to play a critical role on the neuroprotection and inhibiting apoptosis via the enhancing expression of the SODs. This pathway appears to be crucial in Alzheimer’s disease because it is related to the tau protein hyper-phosphorylation. Dietary supplementation of several ordinary compounds may provide a novel therapeutic approach to brain disorders by modulating the function of the PI3K/AKT pathway. Understanding these systems may offer a better efficacy of new therapeutic approaches. In this review, we summarize recent progresses on the involvement of the SODs and PI3K/AKT pathway in neuroprotective signaling against Alzheimer’s disease.

Beneficial psychological effects of novel psychobiotics in diabetic rats: the interaction among the gut, blood and amygdala

Type 2 diabetes mellitus (T2DM) can lead to major complications such as psychiatric disorders which include depressive and anxiety-like behaviors. The association of the gut-brain axis in the development of such disorders, especially in T2DM, has been elucidated; however, gut dysbiosis is also reported in patients with T2DM. Hence, the regulation of the gut-brain axis, in particular, the gut-amygdala, as a vital region for the regulation of behavior is essential. Thirty-five male Wistar rats were divided into six groups. To induce T2DM, treatment groups received high-fat diet and 35 mg/kg streptozotocin. Then, supplements of Lactobacillus plantarum, inulin or their combination were administered to each group for 8 weeks. Finally, the rats were sacrificed for measurement of blood and tissue parameters after behavioral testing. The findings demonstrated the favorable effects of the psychobiotics (L. plantarum, inulin or their combination) on oxidative markers of the blood and amygdala (superoxide dismutase, glutathione peroxidase, malondialdehyde and total antioxidant capacity), as well as on concentrations of amygdala serotonin and brain-derived neurotrophic factor, in the diabetic rats. In addition, beneficial effects were observed on the elevated plus maze and forced swimming tests with no change in locomotor activity of the rats. There was a strong correlation between the blood and amygdala oxidative markers, insulin and fasting blood sugar with depressive and anxiety-like behaviors. Our results identified L. plantarum ATCC 8014 and inulin or their combination as novel psychobiotics that could improve the systemic and nervous antioxidant status and improve amygdala performance and beneficial psychotropic effects.

Preventive effects of crocin on neuronal damages induced by D-galactose through AGEs and oxidative stress in human neuroblastoma cells (SH-SY5Y)

Objective

D-galactose (D-gal) is well-known agent to induce aging process. In the present study, we selected crocin, the main constituent of Crocus sativus L. (saffron), against D-gal-induced cytotoxicity in human neuroblastoma SH-SY5Y cells.

Methods

Pretreated cells with crocin (25–500 μM, 24 h) were exposed to D-gal (25–400 mM, 48 h). The MTT assay was used for determination cell viability. Dichlorofluorescin diacetate assay (DCF-DA) and senescence associated β-galactosidase staining assay (SA-β-gal) were used to evaluate the generation of reactive oxygen species and beta-galactosidase as an aging marker, respectively. Also advanced glycation end products (AGEs) expression which is known as the main mechanism of age-related diseases was measured by western blot analysis.

Results

The findings of our study showed that treatment of cells with D-gal (25–400 mM) for 48h decreased cell viability concentration dependency. Reactive oxygen species (ROS) levels which are known as main factors in age-related diseases increased from 100 ± 8% in control group to 132 ± 22% in D-gal (200 mM) treated cells for 48h. The cytotoxic effects of D-gal decreased with 24h crocin pretreatment of cells. The cell viability at concentrations of 100 μM, 200 μM and 500 μM increased and ROS production decreased at concentrations of 200 and 500 μM to 111.5 ± 6% and 108 ± 5%, respectively. Also lysosomal biomarker of aging and carboxymethyl lysine (CML) expression as an AGE protein, significantly increased in D-gal 200 mM group after 48h incubation compare to control group. Pretreatment of SHSY-5Y cells with crocin (500 μM) before adding D-gal significantly reduced aging marker and CML formation.

Conclusion

Treatment of SH-SY5Y cells with crocin before adding of D-gal restored aging effects of D-gal concentration dependency. These findings indicate that crocin has potent anti-aging effects through inhibition of AGEs and ROS production.

Rosmarinic acid protects against chronic ethanol-induced learning and memory deficits in rats

OBJECTIVES

Ethanol consumption induces neurological disorders including cognitive dysfunction. Oxidative damage is considered a likely cause of cognitive deficits. We aimed to investigate the effects of rosmarinic acid (RA) in different doses for 30 days on chronic ethanol-induced cognitive dysfunction using the passive avoidance learning (PAL) and memory task in comparison with donepezil, a reference drug. We also evaluated the levels of superoxide dismutase (SOD), catalase (CAT), and lipid peroxidation in hippocampus as possible mechanisms.

METHODS

Memory impairment was induced by 15% w/v ethanol (2 g/kg, i.g.) administration for 30 days. RA (8, 16, and 32 mg/kg, i.g.) or donepezil (2 mg/kg, i.g.) was administered 30 minutes before ethanol. The acquisition trial was done 1 hour after the last administration of RA and donepezil. At the end, animals were weighed and hippocami were isolated for analyzing of oxidant/antioxidant markers.

RESULTS

Ethanol caused cognition deficits in the PAL and memory task. While RA 16 and 32 mg/kg improved cognition in control rats, it prevented learning and memory deficits of alcoholic groups. RA 8 mg/kg did not influence cognitive function in both control and alcoholic rats. RA 32 mg/kg had comparable effects with donepezil in prevention of acquisition and retention memory impairment. The higher doses of RA not only prevented increased lipid peroxidation and nitrite content but also decreased SOD, CAT, GSH, and FRAP levels in alcoholic groups and exerted antioxidant effects in non-alcoholic rats.

DISCUSSION

We showed that RA administration dose-dependently prevented cognitive impairment induced by chronic ethanol in PAL and memory and disturbed oxidant/antioxidant status as a possible mechanism. The antioxidant, anticholinesterase, and neuroprotective properties of RA may be involved in the observed effects. Therefore, RA represents a potential therapeutic option against chronic ethanol-induced amnesia which deserves consideration and further examination.

Prunella vulgaris L., an Edible and Medicinal Plant, Attenuates Scopolamine-Induced Memory Impairment in Rats

Prunella vulgaris L. is as a major plant in the Chinese traditional functional beverage Guangdong herbal tea for the treatment of fevers, diarrhea, and sore mouth. In this study, ethyl acetate parts of aqueous extracts from P. vulgaris L. (EtOAc-APV) were found to demonstrate potent acetylcholinesterase (AChE) inhibition in vitro. Therefore, this study was designed to further investigate the effects of EtOAc-APV on scopolamine (SCOP)-induced aging rats. Male Wistar rats were randomly divided into four groups (n = 12) and given orally by gavage EtOAc-APV (100 mg/kg) for 3 weeks. SCOP (1 mg/kg, ip) was administered to rats 30 min before starting behavioral tests consecutively for 3 days. EtOAc-APV could attenuate SCOP-induced brain senescence in rats by improving behavioral performance and decreasing brain cell damage, which was associated with a notable reduction in AChE activity and MDA level, as well as an increase in SOD and GPx activities. Additionally, EtOAc-APV administration could reduce the expression of NF-κB and GFAP, which showed an anti-neuroinflammatory effect on the SCOP-treated rat. Overall, the current study highlights P. vulgaris L. as an antidementia dietary supplement.

Effect of Temperature, pH, Enzyme to Substrate Ratio, Substrate Concentration and Time on the Antioxidative Activity of Hydrolysates from Goat Milk Casein by Alcalase

The effect of hydrolysis temperature (45, 50, 55, 60 and 65°C), pH (7.0, 7.5, 8.0, 8.5 and 9.0), enzyme to substrate (E/S) ratio (1.0, 1.5, 2.0, 2.5 and 3.0%), substrate concentration (2, 3, 4, 5 and 6%) and hydrolysis time (30-240min) on antioxidant peptides hydrolysated from goat’s milk casein by Alcalase was investigated using single factor experiment. In order to obtain high DPPH radical-scavenging activity, metal-chelating activity and superoxide radical scavenging activity, the optimal conditions were hydrolysis time of 150 min, temperature of 50°C, pH 8.0, E/S ratio of 2.0% and substrate concentration of 4.0%. The hydrolysis time, hydrolysis temperature, pH, E/S ratio and substrate concentration had a significant influence on degree of hydrolysis, metal-chelating activity, DPPH and superoxide radical scavenging activity on casein hydrolysate of goat milk by Alcalase, the results were beneficial for further provide theoretical basis for production of antioxidant peptides.

Abdominal obesity is associated with impaired cognitive function in euthymic bipolar individuals

OBJECTIVES

Overweight/obesity has been implicated to play a role in cognitive deficits in bipolar disorder (BD). This study aims to identify the relationship between body fat distribution and different domains of cognition in BD during euthymia.

METHODS

A sample of 100 euthymic individuals with BD was measured with a cognitive test battery (i.e., Trail Making Test-A-B/TM-A/B, d2 Test of Attention, Stroop test, California Verbal Learning Test/CVLT) and an anthropometric measures set (body mass index, waist circumference, hip circumference, waist-to-hip-ratio, waist-to-height-ratio, and lipometry). Patient data were compared with a healthy control group (n = 64).

RESULTS

Results show that overweight patients with BD exhibit lower performance in the TMT-A/B as well as in the free recall performance of the CVLT compared to normal-weight patients with BD and controls. In bipolar individuals, (abdominal) obesity was significantly associated with a poor cognitive performance. In bipolar females, associations with measures of verbal learning and memory were found; in bipolar males, associations with poor performance in the TMT-A/B and in the Stroop interference task were demonstrated. In controls, no associations were found.

CONCLUSIONS

There are several possible pathways moderating the association between obesity and cognition in BD. Anthropometric and lipometry data underline the substantial mediating impact of body fat distribution on cognition in BD.

The combined effects of developmental lead and ethanol exposure on hippocampus dependent spatial learning and memory in rats: Role of oxidative stress

Either developmental lead or ethanol exposure can impair learning and memory via induction of oxidative stress, which results in neuronal damage. we examined the effect of combined exposure with lead and ethanol on spatial learning and memory in offspring and oxidative stress in hippocampus. Rats were exposed to lead (0.2% in drinking water) or ethanol (4 g/kg) either individually or in combination in 5th day gestation through weaning. On postnatal days (PD) 30, rats were trained with six trials per day for 6 consecutive days in the water maze. On day 37, a probe test was done. Also, oxidative stress markers in the hippocampus were also evaluated. Results demonstrated that lead + ethanol co-exposed rats exhibited higher escape latency during training trials and reduced time spent in target quadrant, higher escape location latency and average proximity in probe trial test. There was significant decrease in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities and increase of malondialdehyde (MDA) levels in hippocampus of animals co-exposed to lead and ethanol compared with their individual exposures. We suggest that maternal consumption of ethanol during lead exposure has pronounced detrimental effects on memory, which may be mediated by oxidative stress.

Protective effects of blueberry drink on cognitive impairment induced by chronic mild stress in adult rats

BACKGROUND/OBJECTIVES

Stress-induced cognitive impairment is related to the suppression of hippocampal neurogenesis that results from an increase of oxidative stress. Therefore, the aim of this study was to investigate the effects of administration of a blueberry drink, having a high antioxidant power, on the cognitive performance of adult rats exposed to chronic mild stress.

MATERIALS/METHODS

Twelve-week-old male Sprague-Dawley rats (n = 48) were randomly divided into four groups: control (CO), stress (ST), control + 5% blueberry drink (CO + B), and stress + 5% blueberry drink (ST + B). After eight weeks, the cognitive performance was assessed using a multiple T-maze water test. Levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and ascorbic acid were measured in the brain, and catecholamine concentrations were measured in plasma.

RESULTS

The brain weights of the rats from the ST and ST + B groups were significantly lower than those of the rats from the CO and CO + B groups. The cognitive performance of the ST group was impaired when compared to that of the CO group. This impairment was significantly improved by the blueberry drink supplementation (P < 0.05). The brain SOD and CAT concentrations were not influenced by the stress or by the blueberry drink. However, the brain levels of GPx and ascorbic acid were significantly lower in the ST group than those in the CO group and were increased by the blueberry drink supplementation. The plasma catecholamine concentrations were affected by chronic mild stress and by the blueberry drink. The plasma norepinephrine and dopamine concentrations were decreased by the chronic stress and improved by the blueberry drink supplementation. The plasma epinephrine level was only influenced by the stress.

CONCLUSION

These findings suggest that the blueberry drink may protect against the cognitive impairment induced by chronic mild stress.

Mauritia flexuosa L. protects against deficits in memory acquisition and oxidative stress in rat hippocampus induced by methylmercury exposure

OBJECTIVE

Methylmercury (MeHg) is the most toxic form of mercury that can affect humans through the food chain by bioaccumulation. Human organism is capable of triggering visual and cognitive disorders, neurodegeneration, as well as increased production of reactive species of O2 and depletion of natural anti-oxidant agents. In this context, Mauritia flexuosa L., a fruit rich in compounds with anti-oxidant properties, emerged as an important strategy to prevent the MeHg damages. So, this work has aimed to elucidate the protective effect of Mauritia flexuosa L. on the damage caused by the exposure of rats to MeHg.

METHODS

In order to evaluate the effect of MeHg on rat aversive memory acquisition and panic-like behavior, we have used elevated T-maze apparatus and after behavioral test, the hippocampus was removed to perfom lipid peroxidation.

RESULTS

Our results demonstrated that the exposure to MeHg caused deficits in inhibitory avoidance acquisition (aversive conditioning) and in the learning process, and increased levels of lipid peroxidation in hippocampus tissue. However, the pretreatment with feed enriched with Mauritia flexuosa L. showed a protective effect against cognitive deficits caused by MeHg and also prevented the occurrence of cytoplasmic membrane damage induced by lipid peroxidation in the hippocampal region.

DISCUSSION

Therefore, this study suggests that Mauritia flexuosa L. represents an important strategy to prevent neurocytotoxics and behavioral effects of MeHg.

Inconsistency of Association between Coffee Consumption and Cognitive Function in Adults and Elderly in a Cross-Sectional Study (ELSA-Brasil)

Background: Coffee is one of the most consumed beverages worldwide and the effect on cognition appears to be task specific and vary by age. Method: In cohort of 14,563 public service workers (35–74 years old) we assessed coffee consumption habits and examined cognitive function using standardized neuropsychological test battery. By linear regression and generalize linear regression with logarithmic link and gamma distribution we investigated the relation of coffee consumption (never/almost never, ≤1 cup/day, 2–3 cups/day, ≥3 cups/day) in the last 12 months to performance on specific domains of cognition for adults and elderly separately. Results: Among elderly, after adjustments, coffee consumption was associated only with an increase in the mean words remembered on learning, recall, and word recognition tests when comparing the 2–3 cups/day to never/almost never category (arithmetic mean ratio (AMR): 1.03; 95% Confidence Interval (CI): 1.00 to 1.07), and to an increase in the mean words pronounced in semantic verbal fluency test when comparing the ≥3 cups/day to never/almost never category (difference of the mean: 1.23; 95% CI: 0.16 to 2.29). However, coffee consumption was not associated with any cognitive function tests in adults and also was not associated with the phonemic verbal fluency test and trail-making test B in elderly. Conclusions: Results suggest that coffee consumption might be slightly beneficial to memory in elderly but lacks a dose response relationship. Longitudinal analyses are needed to investigate possible, even if subtle, positive effects of coffee drinking on specific cognitive domains in elderly.