Oxidative Stress in the Brain: Basic Concepts and Treatment Strategies in Stroke

Two Argan Oil Phytosterols, Schottenol and Spinasterol, Attenuate Oxidative Stress and Restore LPS-Dysregulated Peroxisomal Functions in Acox1-/- and Wild-Type BV-2 Microglial Cells

Oxidative stress and inflammation are the key players in neuroinflammation, in which microglia dysfunction plays a central role. Previous studies suggest that argan oil attenuates oxidative stress, inflammation, and peroxisome dysfunction in mouse brains. In this study, we explored the effects of two major argan oil (AO) phytosterols, Schottenol (Schot) and Spinasterol (Spina), on oxidative stress, inflammation, and peroxisomal dysfunction in two murine microglial BV-2 cell lines, wild-ype (Wt) and Acyl-CoA oxidase 1 (Acox1)-deficient cells challenged with LPS treatment. Herein, we used an MTT test to reveal no cytotoxicity for both phytosterols with concentrations up to 5 µM. In the LPS-activated microglial cells, cotreatment with each of these phytosterols caused a significant decrease in intracellular ROS production and the NO level released in the culture medium. Additionally, Schot and Spina were able to attenuate the LPS-dependent strong induction of Il-1β and Tnf-α mRNA levels, as well as the iNos gene and protein expression in both Wt and Acox1-/- microglial cells. On the other hand, LPS treatment impacted both the peroxisomal antioxidant capacity and the fatty acid oxidation pathway. However, both Schot and Spina treatments enhanced ACOX1 activity in the Wt BV-2 cells and normalized the catalase activity in both Wt and Acox1-/- microglial cells. These data suggest that Schot and Spina can protect cells from oxidative stress and inflammation and their harmful consequences for peroxisomal functions and the homeostasis of microglial cells. Collectively, our work provides a compelling argument for the protective mechanisms of two major argan oil phytosterols against LPS-induced brain neuroinflammation.

Fatty acid-binding proteins 3 and 5 are involved in the initiation of mitochondrial damage in ischemic neurons

We have previously shown that a fatty acid-binding protein7 (FABP7) inhibitor ameliorates cerebral ischemia-reperfusion injury in mice, suggesting an association between FABPs and ischemic neuronal injury. However, the precise role of FABPs in ischemic neuronal injury remains unclear. In this study, we investigated the role of FABPs in ischemia-reperfusion neuronal injury. FABP3, FABP5, and FABP7 were upregulated in the ischemic penumbra regions in mice. However, only FABP3 and FABP5 were expressed in injured neurons. Furthermore, FABP3 and FABP5 accumulated in the mitochondria of ischemic neurons. Overexpressing either FABP3 or FABP5 aggravated the reduced mitochondrial membrane potential and induced cell death in human neuroblastoma SH-SY5Y cells during oxidative stress. This damage was mediated by the formation of BAX-containing pores in the mitochondrial membrane. Moreover, FABP5 mediates lipid peroxidation and generates toxic by-products (i.e., 4-HNE) in SH-SY5Y cells. HY11-08 (HY08), a novel FABP3 and 5 inhibitor that does not act on FABP7, significantly reduced cerebral infarct volume and blocked FABP3/5-induced mitochondrial damage, including lipid peroxidation and BAX-related apoptotic signaling. Thus, FABP3 and FABP5 are key players in triggering mitochondrial damage in ischemic neurons. In addition, the novel FABP inhibitor, HY08, may be a potential neuroprotective treatment for ischemic stroke.

Protein Glutathionylation and Glutaredoxin: Role in Neurodegenerative Diseases

Oxidative stress has been implicated in the pathogenesis and progression of many neurodegenerative disorders including Parkinson's disease and Alzheimer's disease. One of the major enzyme systems involved in the defense against reactive oxygen species are the tripeptide glutathione and oxidoreductase glutaredoxin. Glutathione and glutaredoxin system are very important in the brain because of the oxidative modification of protein thiols to protein glutathione mixed disulfides with the concomitant formation of oxidized glutathione during oxidative stress. Formation of Pr-SSG acts as a sink in the brain and is reduced back to protein thiols during recovery, thus restoring protein functions. This is unlike in the liver, which has a high turnover of glutathione, and formation of Pr-SSG is very minimal as liver is able to quickly quench the prooxidant species. Given the important role glutathione and glutaredoxin play in the brain, both in normal and pathologic states, it is necessary to study ways to augment the system to help maintain the protein thiol status. This review details the importance of glutathione and glutaredoxin systems in several neurodegenerative disorders and emphasizes the potential augmentation of this system as a target to effectively protect the brain during aging.

Association between Dietary Total Antioxidant Capacity of Antioxidant Vitamins and the Risk of Stroke among US Adults

The intake of antioxidant vitamins can scavenge free radicals and reduce oxidative stress, which may be beneficial for stroke. However, the relationship between total antioxidant capacity (TAC) of antioxidant vitamins and stroke is controversial. This study aims to investigate the association between dietary TAC and the risk of stroke in US adults. This study included participants over 20 years old from the 2001-2018 National Health and Nutrition Examination Survey (NHANES). Data from two 24 h dietary recalls were used to estimate the usual intake of antioxidant vitamins. TAC was calculated by the vitamin C equivalent antioxidant capacity reference values of individual antioxidant vitamins. Survey-weighted generalized linear models were performed to evaluate the relationship between TAC and the risk of stroke. A restricted cubic spline regression model was used to investigate the dose-response association. A total of 37,045 participants was involved, of whom 1391 suffered a stroke. Compared with the first tertile, the participants in the second tertile of TAC showed a lower risk of stroke (OR = 0.788, 95% CI: 0.662, 0.936) after adjusting for potential risk factors. The dose-response analysis showed a gradual increase in the risk of stroke as TAC decreases. Subgroups analyses indicated that this association was primarily in the population of those aged over 60 years old, who were female, consumed alcohol, were a former smoker and inactive. The sensitivity analysis presented consistent results. These results suggest that deficiency of dietary TAC was associated with an increased risk of stroke, particularly in populations with underlying oxidative stress injury.

Randomization to Treadmill Training Improves Physical and Metabolic Health in Association With Declines in Oxidative Stress in Stroke

OBJECTIVE

To investigate the effect of aerobic exercise vs control (stretching/balance) on inflammatory and oxidative stress biomarkers in stroke survivors and whether these changes are associated with improvements in physical and metabolic health.

DESIGN

Randomized controlled trial.

SETTING

The general communities of Baltimore, Maryland, and Atlanta, Georgia.

PARTICIPANTS

Two hundred forty-six older (>50 years), chronic (>6 months) survivors of stroke (N=246) with hemiparetic gait were recruited, with 51 completing pre-intervention testing and 39 completing postintervention testing. Participants were required to have completed all conventional physical therapy and be capable of walking 3 minutes on a treadmill (N=246).

INTERVENTION

Participants completed 6 months of 2 times/wk stretching or balance (ST; n=19) or 3 times/wk aerobic treadmill rehabilitation (TM; n=20;).

MAIN OUTCOME MEASURE(S)

Peak oxygen uptake rate (V̇o2peak), 6-minute walking distance (6MWD), fasting plasma glucose, insulin, oxidative stress, and inflammatory biomarkers were assessed pre- and postintervention. Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) was calculated.

RESULTS

Physical function and metabolic health parameters tended to improve after TM but not ST (ST vs TM: V̇o2peak: -9% vs 24%, P<.01; 6MWD: 1% vs 15%, P=.05; insulin: -1% vs -31%, P=.05; HOMA-IR: -3% vs -29%, P=.06). Plasma concentrations of nitrotyrosine, protein carbonyls, and oxidized low-density lipoprotein (oxLDL) tended to decrease from pre-intervention concentrations in response to TM compared to ST (ST vs TM: nitrotyrosine: 2% vs -28%, P=.01; protein carbonyls: -4% vs -34%, P=.08; oxLDL: -3% vs -32%, P<.01). Changes in circulating concentrations of C-reactive protein, protein carbonyls, and oxLDL were negatively associated with changes in V̇o2peak and 6MWD (r's=-0.40 to -0.76) and positively associated with fasting plasma insulin and HOMA-IR (r's=0.52-0.81, Ps<.01).

CONCLUSIONS

Six months of TM tends to be associated with increased functional capacity and reduced oxidative stress in chronic stroke survivors. Our findings identify potentially modifiable systemic markers of inflammation and oxidative stress important to stroke rehabilitation and provide potential targets for novel therapeutics in future studies.

AATF Competitively Interacts with Nuclear AIF and Inhibits Parthanatos of Neurons in dMCAO/R and OGD/R Models

Ischemic stroke (IS) poses a heavy burden on the healthcare system, and revascularization is the most effective treatment. However, ischemia/reperfusion (I/R) injury, one main cause of revascularization complications, significantly hinders IS recovery. Unfortunately, none of the neuroprotectants tested to date has been successfully translated clinically for post-revascularization I/R injury therapy. In multiple pathophysiological processes, apoptosis antagonizing transcription factor (AATF) serves as a cell protector, but its role in neuronal I/R injury is unknown. Therefore, we firstly demonstrated the expression profiles of AATF in a distal middle cerebral artery occlusion/reperfusion (dMCAO/R) model and found that AATF expression was increased in cortical neuron after dMCAO/R. Over-expressing AATF reduced infarct volume, alleviated neuronal death, and promoted neurological functions. Next, we used an oxygen-glucose deprivation/reoxygenation (OGD/R) model to investigate the mechanism of AATF. Results indicated that AATF alleviated OGD/R-induced large-scale DNA fragmentation, which suggested that the protective effect of AATF may be attributed to parthanatos inhibition. After that, we examined the regulatory mechanism of AATF. We found that AATF did not affect poly (ADP-ribose) accumulation and apoptosis-inducing factor (AIF) nucleus translocation. AATF competitively interacted with nuclear AIF, which inhibited AIF from binding DNA. At last, we verified the effect and mechanism of AATF in dMCAO/R model. The present study, for the first time, demonstrates the expression, function, and mechanism of AATF in the context of neuronal I/R injury via dMCAO/R and OGD/R model, which provides new evidence in this area and may facilitate exploring new therapeutic targets.

Meteorin-Like Protein Levels Decrease in Patients With Acute Ischaemic Stroke

INTRODUCTION

 Ongoing research aims to investigate blood-based biomarkers and use them in acute ischaemic stroke (AIS) diagnosis and management of patients with AIS.

PURPOSE

The purpose of the present study was to investigate the meteorin-like protein (Metrnl) levels secreted by adipose tissue in patients with AIS.

METHODS

The study groups included healthy controls (n=30) and patients diagnosed with AIS via magnetic resonance imaging (MRI) in the emergency department (n=35) during the one-year period. The basic laboratory values and Metrnl, total antioxidant capacity (TAC), total oxidant status (TOS), and oxidative stress index (OSI) levels of the patients were compared. The Metrnl levels were measured using enzyme-linked immunosorbent assays.

RESULTS

In the present study, the Metrnl (p=0.001) and TAC (p=0.009) levels decreased significantly, whereas the TOS (p<0.001) and OSI (p<0.001) levels increased significantly in the patients with AIS compared to the healthy controls. Furthermore, a cut-off value of ≤1.63% meteorin-like protein rendered the sensitivity and specificity rates of 91.43% and 71.43%, respectively, in the patients with AIS. In addition, there was a significant negative correlation between the decreased meteorin-like protein levels and the infarct diameter in patients with AIS.

CONCLUSION

In patients with AIS, the meteorin-like protein levels decreased inversely with the infarct diameter, and at the same time, there was an increase in TOS and OSI levels and a decrease in TAC levels.

Venous stroke–a stroke subtype that should not be ignored

Based on the etiology, stroke can be classified into ischemic or hemorrhagic subtypes, which ranks second among the leading causes of death. Stroke is caused not only by arterial thrombosis but also by cerebral venous thrombosis. Arterial stroke is currently the main subtype of stroke, and research on this type has gradually improved. Venous thrombosis, the particular type, accounts for 0.5–1% of all strokes. Due to the lack of a full understanding of venous thrombosis, as well as its diverse clinical manifestations and neuroimaging features, there are often delays in admission for it, and it is easy to misdiagnose. The purpose of this study was to review the pathophysiology mechanisms and clinical features of arterial and venous thrombosis and to provide guidance for further research on the pathophysiological mechanism, clinical diagnosis, and treatment of venous thrombosis. This review summarizes the pathophysiological mechanisms, etiology, epidemiology, symptomatology, diagnosis, and treatment heterogeneity of venous thrombosis and compares it with arterial stroke. The aim is to provide a reference for a comprehensive understanding of venous thrombosis and a scientific understanding of various pathophysiological mechanisms and clinical features related to venous thrombosis, which will contribute to understanding the pathogenesis of intravenous stroke and provide insight into diagnosis, treatment, and prevention.

Zingiber officinale and Vernonia amygdalina Infusions Improve Redox Status in Rat Brain

The study investigated the effects of Zingiber officinale root and Vernonia amygdalina leaf on the brain redox status of Wistar rats. Twenty-four (24) rats weighing 160 ± 20 g were randomly assigned into four (4) groups, each with six (6) rats. Animals in Group 1 (control) were orally administered distilled water (1 mL), while the test groups were orally administered 5 mg/mL of either Z. officinale, V. amygdalina infusion, or a combination of both, respectively, for 7 days. The rats were sacrificed at the end of treatments and blood and tissue were harvested and prepared for biochemical assays. Results showed that administration of V. amygdalina and Z. officinale, as well as their coadministration, reduced the levels of malondialdehyde (MDA), nitric oxide (NO), acetylcholinesterase (AChE), and myeloperoxidase (MPO) in rat brain tissue compared with the control group. Conversely, coadministration of V. amygdalina and Z. officinale increased the levels of reduced glutathione (GSH) in rat brain tissue compared with the control group. However, the administration of the infusions singly, as well as the combination of both infusions, did not have any effect on the rat brain levels of glutathione peroxidase (GPx) and catalase (CAT) antioxidant enzymes compared to the control. Taken together, the findings indicate that the V. amygdalina and Z. officinale tea infusions have favorable antioxidant properties in the rat brain. The findings are confirmatory and contribute to deepening our understanding of the health-promoting effects of V. amygdalina and Z. officinale tea infusions.

A quantitative meta-analysis of vitamin C in the pathophysiology of Alzheimer’s disease

Purpose

Alzheimer’s disease (AD) is a multifaceted neurodegenerative disorder with many complex pathways feeding into its pathogenesis and progression. Vitamin C, an essential dietary antioxidant, is vital for proper neurological development and maintenance. This meta-analysis and systematic review attempted to define the relationship between vitamin C plasma levels and AD while highlighting the importance and involvement of vitamin C in the pathogenesis of AD.

Materials and methods

PRISMA guidelines were used to obtain studies quantifying the plasma levels of vitamin C in AD and control subjects. The literature was searched in the online databases PubMed, Google Scholar, and Web of Science. A total of 12 studies were included (n = 1,100) and analyzed using Comprehensive Meta-Analysis 3.0.

Results

The results show that there is a significant decrease in the plasma vitamin C levels of AD patients as compared to healthy controls (pooled SMD with random-effect model: −1.164, with 95%CI: −1.720 to −0.608, Z = −4.102, p = 0.00) with significant heterogeneity (I² = 93.218). The sensitivity analysis showed directionally similar results. Egger’s regression test (p = 0.11) and visual inspection of the funnel plot showed no publication bias.

Conclusion

Based on these studies, it can be deduced that the deficiency of vitamin C is involved in disease progression and supplementation is a plausible preventive and treatment strategy. However, clinical studies are warranted to elucidate its exact mechanistic role in AD pathophysiology and prevention.

Quercetin-3-O-β-D-Glucopyranoside-Rich Fraction from Spondias mombin Leaves Halted Responses from Oxidative Stress, Neuroinflammation, Apoptosis, and Lipid Peroxidation in the Brain of Dichlorvos-Treated Wistar Rats

Dichlorvos (2,3-dichlorovinyl dimethyl phosphate or DDVP), is a popular organophosphate (OP) with several domestic, industrial, and agricultural uses and applications in developing countries [...].

The Differences of Metabolites in Different Parts of the Brain Induced by Shuxuetong Injection against Cerebral Ischemia-Reperfusion and Its Corresponding Mechanism

Ischemic stroke is often associated with a large disease burden. The existence of ischemia-reperfusion injury brings great challenges to the treatment of ischemic stroke. The purpose of this study was to explore the differences of metabolites in different parts of the brain induced by Shuxuetong injection against cerebral ischemia-reperfusion and to extend the corresponding mechanism. The rats were modeled by transient middle cerebral artery occlusion (t-MCAO) operation, and the success of modeling was determined by neurological function score and TTC staining. UPLC-Q/TOF-MS metabolomics technique and multivariate statistical analysis were used to analyze the changes and differences of metabolites in the cortex and hippocampus of cerebral ischemia-reperfusion rats. Compared with the model group, the neurological function score and cerebral infarction volume of the Shuxuetong treatment group were significantly different. There were differences and changes in the metabolic distribution of the cortex and hippocampus in each group, the distribution within the group was relatively concentrated. The separation trend between the groups was obvious, and the distribution of the Shuxuetong treatment group was similar to that of the sham operation group. We identified 13 metabolites that were differentially expressed in the cortex, including glutamine, dihydroorotic acid, and glyceric acid. We also found five differentially expressed metabolites in the hippocampus, including glutamic acid and fumaric acid. The common metabolic pathways of Shuxuetong on the cortex and hippocampus were D-glutamine and D-glutamate metabolism and nitrogen metabolism, which showed inhibition of cortical glutamine and promotion of hippocampal glutamic acid. Specific pathways of Shuxuetong enriched in the cortex included glyoxylate and dicarboxylate metabolism and pyrimidine metabolism, which showed inhibition of glyceric acid and dihydroorotic acid. Specific pathways of Shuxuetong enriched in the hippocampus include arginine biosynthesis and citrate cycle (TCA cycle), which promotes fumaric acid. Shuxuetong injection can restore and adjust the metabolic disorder of the cortex and hippocampus in cerebral ischemia-reperfusion rats. The expression of Shuxuetong in different parts of the brain is different and correlated.

Potential Effects of Nrf2 in Exercise Intervention of Neurotoxicity Caused by Methamphetamine Oxidative Stress

Methamphetamine can cause oxidative stress-centered lipid peroxidation, endoplasmic reticulum stress, mitochondrial dysfunction, excitatory neurotoxicity, and neuroinflammation and ultimately lead to nerve cell apoptosis, abnormal glial cell activation, and dysfunction of blood-brain barrier. Protecting nerve cells from oxidative destroy is a hopeful strategy for treating METH use disorder. Nrf2 is a major transcriptional regulator that activates the antioxidant, anti-inflammatory, and cell-protective gene expression through endogenous pathways that maintains cell REDOX homeostasis and is conducive to the survival of neurons. The Nrf2-mediated endogenous antioxidant pathway can also prevent neurodegenerative effects and functional defects caused by METH oxidative stress. Moderate exercise activates this endogenous antioxidant system, which involves in many diseases, including neurodegenerative diseases. Based on evidence from existing literature, we argue that appropriate exercise can play an endogenous antioxidant regulatory role in the Nrf2 signaling pathway to reduce a number of issues caused by METH-induced oxidative stress. However, more experimental evidence is needed to support this idea. In addition, further exploration is necessary about the different effects of various parameters of exercise intervention (such as exercise mode, time, and intensity) on the Nrf2 signaling pathway intervention. Whether there are synergistic effects between exercise and plant-derived Nrf2 activators is worth further investigation.

Insight Into the Mechanism of Exercise Preconditioning in Ischemic Stroke

Exercise preconditioning has attracted extensive attention to induce endogenous neuroprotection and has become the hotspot in neurotherapy. The training exercise is given multiple times before cerebral ischemia, effectively inducing ischemic tolerance and alleviating secondary brain damage post-stroke. Compared with other preconditioning methods, the main advantages of exercise include easy clinical operation and being readily accepted by patients. However, the specific mechanism behind exercise preconditioning to ameliorate brain injury is complex. It involves multi-pathway and multi-target regulation, including regulation of inflammatory response, oxidative stress, apoptosis inhibition, and neurogenesis promotion. The current review summarizes the recent studies on the mechanism of neuroprotection induced by exercise, providing the theoretical basis of applying exercise therapy to prevent and treat ischemic stroke. In addition, we highlight the various limitations and future challenges of translational medicine from fundamental study to clinical application.

Oxidative Stress in Ischemia/Reperfusion Injuries following Acute Ischemic Stroke

Recanalization therapy is increasingly used in the treatment of acute ischemic stroke. However, in about one third of these patients, recanalization is followed by ischemia/reperfusion injuries, and clinically to worsening of the neurological status. Much research has focused on unraveling the involved mechanisms in order to prevent or efficiently treat these injuries. What we know so far is that oxidative stress and mitochondrial dysfunction are significantly involved in the pathogenesis of ischemia/reperfusion injury. However, despite promising results obtained in experimental research, clinical studies trying to interfere with the oxidative pathways have mostly failed. The current article discusses the main mechanisms leading to ischemia/reperfusion injuries, such as mitochondrial dysfunction, excitotoxicity, and oxidative stress, and reviews the clinical trials with antioxidant molecules highlighting recent developments and future strategies.

N-Acetyl-Aspartyl-Glutamate in Brain Health and Disease

N-acetyl-aspartyl-glutamate (NAAG) is the most abundant dipeptide in the brain, where it acts as a neuromodulator of glutamatergic synapses by activating presynaptic metabotropic glutamate receptor 3 (mGluR3). Recent data suggest that NAAG is selectively localized to postsynaptic dendrites in glutamatergic synapses and that it works as a retrograde neurotransmitter. NAAG is released in response to glutamate and provides the postsynaptic neuron with a feedback mechanisms to inhibit excessive glutamate signaling. A key regulator of synaptically available NAAG is rapid degradation by the extracellular enzyme glutamate carboxypeptidase II (GCPII). Increasing endogenous NAAG—for instance by inhibiting GCPII—is a promising treatment option for many brain disorders where glutamatergic excitotoxicity plays a role. The main effect of NAAG occurs through increased mGluR3 activation and thereby reduced glutamate release. In the present review, we summarize the transmitter role of NAAG and discuss the involvement of NAAG in normal brain physiology. We further present the suggested roles of NAAG in various neurological and psychiatric diseases and discuss the therapeutic potential of strategies aiming to enhance NAAG levels.