Oxidative Stress: A Major Player in Cerebrovascular Alterations Associated to Neurodegenerative Events

L-Arginine and Taurisolo® Effects on Brain Hypoperfusion-Reperfusion Damage in Hypertensive Rats

Acute and chronic hypertension causes cerebral vasculopathy, increasing the risk of ischemia and stroke. Our study aimed to compare the effects of arterial pressure reduction on the pial microvascular responses induced by hypoperfusion and reperfusion in spontaneously hypertensive Wistar rats, desamethasone-induced hypertensive Wistar rats and age-matched normotensive Wistar rats fed for 3 months with a normal diet or normal diet supplemented with L-arginine or Taurisolo® or L-arginine plus Taurisolo®. At the end of treatments, the rats were submitted to bilateral occlusion of common carotid arteries for 30 min and reperfusion. The microvascular parameters investigated in vivo through a cranial window were: arteriolar diameter changes, permeability increase, leukocyte adhesion to venular walls and percentage of capillaries perfused. Hypoperfusion-reperfusion caused in all rats marked microvascular changes. L-arginine treatment was effective in reducing arterial blood pressure causing vasodilation but did not significantly reduce the damage induced by hypoperfusion-reperfusion. Taurisolo® treatment was less effective in reducing blood pressure but prevented microvascular damage from hypoperfusion-reperfusion. L-arginine plus Taurisolo® maintained blood pressure levels within the physiological range and protected the pial microcirculation from hypoperfusion-reperfusion-induced microvascular injuries. Therefore, the blood pressure reduction is not the only fundamental aspect to protect the cerebral circulation from hypoperfusion-reperfusion damage.

The Role of Pericytes in Inner Ear Disorders: A Comprehensive Review

Inner ear disorders, including sensorineural hearing loss, Meniere's disease, and vestibular neuritis, are prevalent conditions that significantly impact the quality of life. Despite their high incidence, the underlying pathophysiology of these disorders remains elusive, and current treatment options are often inadequate. Emerging evidence suggests that pericytes, a type of vascular mural cell specialized to maintain the integrity and function of the microvasculature, may play a crucial role in the development and progression of inner ear disorders. The pericytes are present in the microvasculature of both the cochlea and the vestibular system, where they regulate blood flow, maintain the blood-labyrinth barrier, facilitate angiogenesis, and provide trophic support to neurons. Understanding their role in inner ear disorders may provide valuable insights into the pathophysiology of these conditions and lead to the development of novel diagnostic and therapeutic strategies, improving the standard of living. This comprehensive review aims to provide a detailed overview of the role of pericytes in inner ear disorders, highlighting the anatomy and physiology in the microvasculature, and analyzing the mechanisms that contribute to the development of the disorders. Furthermore, we explore the potential pericyte-targeted therapies, including antioxidant, anti-inflammatory, and angiogenic approaches, as well as gene therapy strategies.

PNA5, A Novel Mas Receptor Agonist, Improves Neurovascular and Blood-Brain-Barrier Function in a Mouse Model of Vascular Cognitive Impairment and Dementia

It is well established that decreased brain blood flow, increased reactive oxygen species production (ROS), and pro-inflammatory mechanisms accelerate neurodegenerative disease progressions, including vascular cognitive impairment and dementia (VCID). Previous studies in our laboratory have shown that our novel glycosylated Angiotensin-(1-7) Mas receptor agonist PNA5 reverses cognitive deficits, decreases ROS production, and inhibits inflammatory cytokine production in our preclinical mouse model of VCID that is induced by chronic heart failure (VCID-HF). In the present study, the effects of VCID-HF and treatment with PNA5 on microglia activation, blood-brain-barrier (BBB) integrity, and neurovascular coupling were assessed in our mouse model of VCID-HF. Three-month-old male C57BL/6J mice were subjected to myocardial infarction (MI) to induce heart failure for four weeks and then treated with subcutaneous injections of extended-release PNA5. Microglia activation, BBB permeability, cerebral perfusion, and neurovascular coupling were assessed. Results show that in our VCID-HF model, there was an increase in microglial activation and recruitment within the CA1 and CA3 regions of the hippocampus, a disruption in BBB integrity, and a decrease in neurovascular coupling. Treatment with PNA5 reversed these neuropathological effects of VCID-HF, suggesting that PNA5 may be an effective disease-modifying therapy to treat and prevent VCID. This study identifies potential mechanisms by which heart failure may induce VCID and highlights the possible mechanisms by which treatment with our novel glycosylated Angiotensin-(1-7) Mas receptor agonist, PNA5, may protect cognitive function in our model of VCID.

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.

Upregulation of NADPH-oxidase, inducible nitric oxide synthase and apoptosis in the hippocampus following impaired insulin signaling in the rats: Development of sporadic Alzheimer's disease

NADPH-oxidase (NOX) is a multi-subunit enzyme complex. The upregulation of NOX causes massive production of superoxide (O2¯), which avidly reacts with nitric oxide (NO) and increases cellular reactive oxygen/nitrogen species (ROS/RNS). Increased ROS/RNS plays pivotal role in the sporadic Alzheimer's disease (sAD) development and brain damage following impaired insulin signaling. Hence, this study aimed to examine early-time course of changes in NOX and NOS expression, and apoptotic proteins in the rats hippocampi following insulin signaling impairment [induced by STZ injection; intraperitoneal (IP) or in cerebral ventricles (ICV)]. Early effects (1, 3, or 6 weeks) on the NOX activity, translocation of NOX subunits from cytosol to the membrane, NO-synthases [neuronal-, inducible- and endothelial-NOS; nNOS, iNOS and eNOS], The Rac-1 protein expression, levels of NO and O2¯, cytochrome c release, caspase-3 and 9 activations (cleavage) were studied. STZ injection (in both models) increased NOX activity, O2¯ production, and enhanced cytosolic subunits translocation into membrane. The iNOS but not nNOS and eNOS expression and NO levels were increased in STZ treated rats. Finally, STZ injection increased cytochrome c release, caspase-3 and 9 activations in a manner that was significantly associated with levels of O2¯ and NO in the hippocampus. ICV-STZ administration resulted in significant profound changes over the IP route. In conclusion, impairment in insulin function induces early changes in ROS/RNS contents through NOX and iNOS upregulation and neuronal apoptosis in the hippocampus. Our results could mechanistically explain the role of impaired insulin function in the development of sAD.

Cerebral Microbleeds Associate with Brain Endothelial Cell Activation-Dysfunction and Blood-Brain Barrier Dysfunction/Disruption with Increased Risk of Hemorrhagic and Ischemic Stroke

Globally, cerebral microbleeds (CMBs) are increasingly being viewed not only as a marker for cerebral small vessel disease (SVD) but also as having an increased risk for the development of stroke (hemorrhagic/ischemic) and aging-related dementia. Recently, brain endothelial cell activation and dysfunction and blood-brain barrier dysfunction and/or disruption have been shown to be associated with SVD, enlarged perivascular spaces, and the development and evolution of CMBs. CMBs are a known disorder of cerebral microvessels that are visualized as 3-5 mm, smooth, round, or oval, and hypointense (black) lesions seen only on T2*-weighted gradient recall echo or susceptibility-weighted sequences MRI images. CMBs are known to occur with high prevalence in community-dwelling older individuals. Since our current global population is the oldest recorded in history and is only expected to continue to grow, we can expect the healthcare burdens associated with CMBs to also grow. Increased numbers (≥10) of CMBs should raise a red flag regarding the increased risk of large symptomatic neurologic intracerebral hemorrhages. Importantly, CMBs are also currently regarded as markers of diffuse vascular and neurodegenerative brain damage. Herein author highlights that it is essential to learn as much as we can about CMB development, evolution, and their relation to impaired cognition, dementia, and the exacerbation of neurodegeneration.

The Biological Activity of Ganoderma lucidum on Neurodegenerative Diseases: The Interplay between Different Active Compounds and the Pathological Hallmarks

Neurodegenerative diseases represent a cluster of conditions characterized by the progressive degeneration of the structure and function of the nervous system. Despite significant advancements in understanding these diseases, therapeutic options remain limited. The medicinal mushroom Ganoderma lucidum has been recognized for its comprehensive array of bioactive compounds with anti-inflammatory and antioxidative effects, which possess potential neuroprotective properties. This literature review collates and examines the existing research on the bioactivity of active compounds and extracts from Ganoderma lucidum in modulating the pathological hallmarks of neurodegenerative diseases. The structural information and preparation processes of specific components, such as individual ganoderic acids and unique fractions of polysaccharides, are presented in detail to facilitate structure-activity relationship research and scale up the investigation of in vivo pharmacology. The mechanisms of these components against neurodegenerative diseases are discussed on multiple levels and elaborately categorized in different patterns. It is clearly presented from the patterns that most polysaccharides of Ganoderma lucidum possess neurotrophic effects, while ganoderic acids preferentially target specific pathogenic proteins as well as regulating autophagy. Further clinical trials are necessary to assess the translational potential of these components in the development of novel multi-target drugs for neurodegenerative diseases.

CD8+ T-cell metabolism is related to cerebrovascular reactivity in middle-aged adults

Cerebrovascular reactivity (CVR) decreases with advancing age, contributing to increased risk of cognitive impairment; however, the mechanisms underlying the age-related decrease in CVR are incompletely understood. Age-related changes to T cells, such as impaired mitochondrial respiration, increased inflammation, likely contribute to peripheral and cerebrovascular dysfunction in animals. However, whether T-cell mitochondrial respiration is related to cerebrovascular function in humans is not known. Therefore, we hypothesized that peripheral T-cell mitochondrial respiration would be positively associated with CVR and that T-cell glycolytic metabolism would be negatively associated with CVR. Twenty middle-aged adults (58 ± 5 yr) were recruited for this study. T cells were separated from peripheral blood mononuclear cells. Cellular oxygen consumption rate (OCR) and extracellular acidification rate (ECAR, a marker of glycolytic activity) were measured using extracellular flux analysis. CVR was quantified using the breath-hold index (BHI), which reflects the change in blood velocity in the middle-cerebral artery (MCAv) during a 30-s breath-hold. In contrast to our hypothesis, we found that basal OCR in CD8+ T cells (β = -0.59, R2 = 0.27, P = 0.019) was negatively associated with BHI. However, in accordance with our hypothesis, we found that basal ECAR (β = -2.20, R2 = 0.29, P = 0.015) and maximum ECAR (β = -50, R2 = 0.24, P = 0.029) were negatively associated with BHI in CD8+ T cells. There were no associations observed in CD4+ T cells. These associations appeared to be primarily mediated by an association with the pressor response to the breath-hold test. Overall, our findings suggest that CD8+ T-cell respiration and glycolytic activity may influence CVR in humans.NEW & NOTEWORTHY Peripheral T-cell metabolism is related to in vivo cerebrovascular reactivity in humans. Higher glycolytic metabolism in CD8+ T cells was associated with lower cerebrovascular reactivity to a breath-hold in middle-aged adults, which is possibly reflective of a more proinflammatory state in midlife.

Blood-brain barrier biomarkers

The blood-brain barrier (BBB) is a dynamic interface that regulates the exchange of molecules and cells between the brain parenchyma and the peripheral blood. The BBB is mainly composed of endothelial cells, astrocytes and pericytes. The integrity of this structure is essential for maintaining brain and spinal cord homeostasis and protection from injury or disease. However, in various neurological disorders, such as traumatic brain injury, Alzheimer's disease, and multiple sclerosis, the BBB can become compromised thus allowing passage of molecules and cells in and out of the central nervous system parenchyma. These agents, however, can serve as biomarkers of BBB permeability and neuronal damage, and provide valuable information for diagnosis, prognosis and treatment. Herein, we provide an overview of the BBB and changes due to aging, and summarize current knowledge on biomarkers of BBB disruption and neurodegeneration, including permeability, cellular, molecular and imaging biomarkers. We also discuss the challenges and opportunities for developing a biomarker toolkit that can reliably assess the BBB in physiologic and pathophysiologic states.

Proteomics of mouse brain endothelium uncovers dysregulation of vesicular transport pathways during aging

Age-related decline in brain endothelial cell (BEC) function contributes critically to neurological disease. Comprehensive atlases of the BEC transcriptome have become available, but results from proteomic profiling are lacking. To gain insights into endothelial pathways affected by aging, we developed a magnetic-activated cell sorting-based mouse BEC enrichment protocol compatible with proteomics and resolved the profiles of protein abundance changes during aging. Unsupervised cluster analysis revealed a segregation of age-related protein dynamics with biological functions, including a downregulation of vesicle-mediated transport. We found a dysregulation of key regulators of endocytosis and receptor recycling (most prominently Arf6), macropinocytosis and lysosomal degradation. In gene deletion and overexpression experiments, Arf6 affected endocytosis pathways in endothelial cells. Our approach uncovered changes not picked up by transcriptomic studies, such as accumulation of vesicle cargo and receptor ligands, including Apoe. Proteomic analysis of BECs from Apoe-deficient mice revealed a signature of accelerated aging. Our findings provide a resource for analysing BEC function during aging.

The effect of acupuncture on oxidative stress in animal models of vascular dementia: a systematic review and meta-analysis

BACKGROUND

Growing evidence showed that acupuncture may improve cognitive function by reducing oxidative stress, key to the pathogenesis in vascular dementia (VaD), but this is yet to be systematically analysed. This study aimed to summarize and evaluate the effect of acupuncture on oxidative stress in animal models of VaD.

METHOD

Eight databases including PubMed, Embase, Web of Science, Cochrane library, CNKI, Wan Fang, CBM, and VIP were searched since their establishment until April 2023, for studies that reported the effect of acupuncture on oxidative stress in VaD animal models. Relevant literature was screened, and information was extracted by two reviewers. The primary outcomes were the levels of oxidative stress indicators. The methodological quality was assessed via the SYRCLE Risk of Bias Tool. Statistical analyses were performed using the RevMan and Stata software.

RESULTS

In total, 22 studies with 747 animals were included. The methodology of most studies had flaws or uncertainties. The meta-analysis indicated that, overall, acupuncture significantly reduced the expression of pro-oxidants including reactive oxygen species (standardized mean differences [SMDs] = -4.29, 95% confidence interval [CI]: -6.26, -2.31), malondialdehyde (SMD = -2.27, 95% CI: -3.07, -1.47), nitric oxide (SMD = -0.85, 95% CI: -1.50, -0.20), and nitric oxide synthase (SMD = -1.01, 95% CI: -1.69, -0.34) and enhanced the levels of anti-oxidants including super oxide dismutase (SMD = 2.80, 95% CI: 1.98, 3.61), glutathione peroxidase (SMD = 1.32, 95% CI: -0.11, 2.76), and catalase (SMD = 1.31, 95% CI: 0.05, 2.58) in VaD animal models. In subgroup analyses, acupuncture showed significant effects on most variables. Only partial modelling methods and treatment duration could interpret the heterogeneity of some outcomes.

CONCLUSION

Acupuncture may inhibit oxidative stress to improve cognitive deficits in animal models of VaD. Nevertheless, the methodological quality is unsatisfactory. More high-quality research with a rigorous design and further experimental researches and clinical trials are needed to confirm these findings.

SYSTEMATIC REVIEW REGISTRATION

This study was registered in PROSPERO (CRD42023411720).

Superoxide dismutase 2 deficiency is associated with enhanced central chemoreception in mice: Implications for breathing regulation

AIMS

In mammals, central chemoreception plays a crucial role in the regulation of breathing function in both health and disease conditions. Recently, a correlation between high levels of superoxide anion (O2.-) in the Retrotrapezoid nucleus (RTN), a main brain chemoreceptor area, and enhanced central chemoreception has been found in rodents. Interestingly, deficiency in superoxide dismutase 2 (SOD2) expression, a pivotal antioxidant enzyme, has been linked to the development/progression of several diseases. Despite, the contribution of SOD2 on O2.- regulation on central chemoreceptor function is unknown. Accordingly, we sought to determine the impact of partial deletion of SOD2 expression on i) O2.-accumulation in the RTN, ii) central ventilatory chemoreflex function, and iii) disordered-breathing. Finally, we study cellular localization of SOD2 in the RTN of healthy mice.

METHODS

Central chemoreflex drive and breathing function were assessed in freely moving heterozygous SOD2 knockout mice (SOD2+/- mice) and age-matched control wild type (WT) mice by whole-body plethysmography. O2.- levels were determined in RTN brainstem sections and brain isolated mitochondria, while SOD2 protein expression and tissue localization were determined by immunoblot, RNAseq and immunofluorescent staining, respectively.

RESULTS

Our results showed that SOD2+/- mice displayed reductions in SOD2 levels and high O2.- formation and mitochondrial dysfunction within the RTN compared to WT. Additionally, SOD2+/- mice displayed a heightened ventilatory response to hypercapnia and exhibited overt signs of altered breathing patterns. Both, RNAseq analysis and immunofluorescence co-localization studies showed that SOD2 expression was confined to RTN astrocytes but not to RTN chemoreceptor neurons. Finally, we found that SOD2+/- mice displayed alterations in RTN astrocyte morphology compared to RTN astrocytes from WT mice.

INNOVATION & CONCLUSION

These findings provide first evidence of the role of SOD2 in the regulation of O2.- levels in the RTN and its potential contribution on the regulation of central chemoreflex function. Our results suggest that reductions in the expression of SOD2 in the brain may contribute to increase O2.- levels in the RTN being the outcome a chronic surge in central chemoreflex drive and the development/maintenance of altered breathing patterns. Overall, dysregulation of SOD2 and the resulting increase in O2.- levels in brainstem respiratory areas can disrupt normal respiratory control mechanisms and contribute to breathing dysfunction seen in certain disease conditions characterized by high oxidative stress.

Glycosylation: A new signaling paradigm for the neurovascular diseases

A wide range of life-threatening conditions with complicated pathogenesis involves neurovascular disorders encompassing Neurovascular unit (NVU) damage. The pathophysiology of NVU is characterized by several features including tissue hypoxia, stimulation of inflammatory and angiogenic processes, and the initiation of intricate molecular interactions, collectively leading to an elevation in blood-brain barrier permeability, atherosclerosis and ultimately, neurovascular diseases. The presence of compelling data about the significant involvement of the glycosylation in the development of diseases has sparked a discussion on whether the abnormal glycosylation may serve as a causal factor for neurovascular disorders, rather than being just recruited as a secondary player in regulating the critical events during the development processes like embryo growth and angiogenesis. An essential tool for both developing new anti-ischemic therapies and understanding the processes of ischemic brain damage is undertaking pre-clinical studies of neurovascular disorders. Together with the post-translational modification of proteins, the modulation of glycosylation and its enzymes implicates itself in several abnormal activities which are known to accelerate neuronal vasculopathy. Despite the failure of the majority of glycosylation-based preclinical and clinical studies over the past years, there is a significant probability to provide neuroprotection utilizing modern and advanced approaches to target abnormal glycosylation activity at embryonic stages as well. This article focuses on a variety of experimental evidence to postulate the interconnection between glycosylation and vascular disorders along with possible treatment options.

CCR5 deficiency: Decreased neuronal resilience to oxidative stress and increased risk of vascular dementia

INTRODUCTION

As the chemokine receptor5 (CCR5) may play a role in ischemia, we studied the links between CCR5 deficiency, the sensitivity of neurons to oxidative stress, and the development of dementia.

METHODS

Logistic regression models with CCR5/apolipoprotein E (ApoE) polymorphisms were applied on a sample of 205 cognitively normal individuals and 189 dementia patients from Geneva. The impact of oxidative stress on Ccr5 expression and cell death was assessed in mice neurons.

RESULTS

CCR5-Δ32 allele synergized with ApoEε4 as risk factor for dementia and specifically for dementia with a vascular component. We confirmed these results in an independent cohort from Italy (157 cognitively normal and 620 dementia). Carriers of the ApoEε4/CCR5-Δ32 genotype aged ≥80 years have an 11-fold greater risk of vascular-and-mixed dementia. Oxidative stress-induced cell death in Ccr5-/- mice neurons.

DISCUSSION

We propose the vulnerability of CCR5-deficient neurons in response to oxidative stress as possible mechanisms contributing to dementia.

Montelukast Ameliorates 2K1C-Hypertension Induced Endothelial Dysfunction and Associated Vascular Dementia

BACKGROUND

Declined kidney function associated with hypertension is a danger for cognitive deficits, dementia, and brain injury. Cognitive decline and vascular dementia (VaD) are serious public health concerns, which highlights the urgent need for study on the risk factors for cognitive decline. Cysteinyl leukotriene (CysLT1) receptors are concerned with regulating cognition, motivation, inflammatory processes, and neurogenesis.

OBJECTIVE

This research aims to examine the consequence of montelukast (specific CysLT1 antagonist) in renovascular hypertension 2-kidney-1-clip-2K1C model-triggered VaD in experimental animals.

METHODS

2K1C tactics were made to prompt renovascular hypertension in mature male rats. Morris water maze was employed to measure cognition. Mean arterial pressure (MAP), serum nitrite levels, aortic superoxide content, vascular endothelial activity, brain's oxidative stress (diminished glutathione, raised lipid peroxides), inflammatory markers (IL-10, IL-6, TNF-α), cholinergic activity (raised acetylcholinesterase), and cerebral injury (staining of 2, 3, 5- triphenylterazolium chloride) were also examined.

RESULTS

Montelukast in doses of 5.0 and 10.0 mg kg-1 was used intraperitoneally as the treatment drug. Along with cognitive deficits, 2K1C-operated rats showed elevated MAP, endothelial dysfunction, brain oxidative stress, inflammation, and cerebral damage with diminished serum nitrite/nitrate. Montelukast therapy significantly and dose-dependently mitigated the 2K1Chypertension- provoked impaired behaviors, biochemistry, endothelial functions, and cerebral infarction.

CONCLUSION

The 2K1C tactic caused renovascular hypertension and associated VaD, which was mitigated via targeted regulation of CysLT1 receptors by montelukast administration. Therefore, montelukast may be taken into consideration for the evaluation of its complete potential in renovascular-hypertension-induced VaD.

Thromboxane-induced cerebral microvascular rarefaction predicts depressive symptom emergence in metabolic disease

Previous studies have suggested that the loss of microvessel density in the peripheral circulation with evolving metabolic disease severity represents a significant contributor to impaired skeletal muscle oxygenation and fatigue-resistance. Based on this and our recent work, we hypothesized that cerebral microvascular rarefaction was initiated from the increased prooxidant and proinflammatory environment with metabolic disease and is predictive of the severity of the emergence of depressive symptoms in obese Zucker rats (OZRs). In male OZR, cerebrovascular rarefaction followed the emergence of elevated oxidant and inflammatory environments characterized by increased vascular production of thromboxane A2 (TxA2). The subsequent emergence of depressive symptoms in OZR was associated with the timing and severity of the rarefaction. Chronic intervention with antioxidant (TEMPOL) or anti-inflammation (pentoxifylline) therapy blunted the severity of rarefaction and depressive symptoms, although the effectiveness was limited. Blockade of TxA2 production (dazmegrel) or action (SQ-29548) resulted in a stronger therapeutic effect, suggesting that vascular production and action represent a significant contributor to rarefaction and the emergence of depressive symptoms with chronic metabolic disease (although other pathways clearly contribute as well). A de novo biosimulation of cerebrovascular oxygenation in the face of progressive rarefaction demonstrates the increased probability of generating hypoxic regions within the microvascular networks, which could contribute to impaired neuronal metabolism and the emergence of depressive symptoms. The results of the present study also implicate the potential importance of aggressive prodromic intervention in reducing the severity of chronic complications arising from metabolic disease.NEW & NOTEWORTHY With clinical studies linking vascular disease risk to depressive symptom emergence, we used obese Zucker rats, a model of chronic metabolic disease, to identify potential mechanistic links between these two negative outcomes. Depressive symptom severity correlated with the extent of cerebrovascular rarefaction, after increased vascular oxidant stress/inflammation and TxA2 production. Anti-TxA2 interventions prevasculopathy blunted rarefaction and depressive symptoms, while biosimulation indicated that cerebrovascular rarefaction increased hypoxia within capillary networks as a potential contributing mechanism.

Postictal hypoxia involves reactive oxygen species and is ameliorated by chronic mitochondrial uncoupling

Prolonged severe hypoxia follows brief seizures and represents a mechanism underlying several negative postictal manifestations without interventions. Approximately 50% of the postictal hypoxia phenomenon can be accounted for by arteriole vasoconstriction. What accounts for the rest of the drop in unbound oxygen is unclear. Here, we determined the effect of pharmacological modulation of mitochondrial function on tissue oxygenation in the hippocampus of rats after repeatedly evoked seizures. Rats were treated with mitochondrial uncoupler 2,4 dinitrophenol (DNP) or antioxidants. Oxygen profiles were recorded using a chronically implanted oxygen-sensing probe, before, during, and after seizure induction. Mitochondrial function and redox tone were measured using in vitro mitochondrial assays and immunohistochemistry. Postictal cognitive impairment was assessed using the novel object recognition task. Mild mitochondrial uncoupling by DNP raised hippocampal oxygen tension and ameliorated postictal hypoxia. Chronic DNP also lowered mitochondrial oxygen-derived reactive species and oxidative stress in the hippocampus during postictal hypoxia. Uncoupling the mitochondria exerts therapeutic benefits on postictal cognitive dysfunction. Finally, antioxidants do not affect postictal hypoxia, but protect the brain from associated cognitive deficits. We provided evidence for a metabolic component of the prolonged oxygen deprivation that follow seizures and its pathological sequelae. Furthermore, we identified a molecular underpinning of this metabolic component, which involves excessive oxygen conversion into reactive species. Mild mitochondrial uncoupling may be a potential therapeutic strategy to treat the postictal state where seizure control is absent or poor.

Cell-specific alterations in autophagy-lysosomal activity near the chronically implanted microelectrodes

Intracortical microelectrodes that can record and stimulate brain activity have become a valuable technique for basic science research and clinical applications. However, long-term implantation of these microelectrodes can lead to progressive neurodegeneration in the surrounding microenvironment, characterized by elevation in disease-associated markers. Dysregulation of autophagy-lysosomal degradation, a major intracellular waste removal process, is considered a key factor in the onset and progression of neurodegenerative diseases. It is plausible that similar dysfunctions in autophagy-lysosomal degradation contribute to tissue degeneration following implantation-induced focal brain injury, ultimately impacting recording performance. To understand how the focal, persistent brain injury caused by long-term microelectrode implantation impairs autophagy-lysosomal pathway, we employed two-photon microscopy and immunohistology. This investigation focused on the spatiotemporal characterization of autophagy-lysosomal activity near the chronically implanted microelectrode. We observed an aberrant accumulation of immature autophagy vesicles near the microelectrode over the chronic implantation period. Additionally, we found deficits in autophagy-lysosomal clearance proximal to the chronic implant, which was associated with an accumulation of autophagy cargo and a reduction in lysosomal protease level during the chronic period. Furthermore, our evidence demonstrates reactive astrocytes have myelin-containing lysosomes near the microelectrode, suggesting its role of myelin engulfment during acute implantation period. Together, this study sheds light on the process of brain tissue degeneration caused by long-term microelectrode implantation, with a specific focus on impaired intracellular waste degradation.

In the Rat Midbrain, SG2NA and DJ-1 have Common Interactome, Including Mitochondrial Electron Transporters that are Comodulated Under Oxidative Stress

Scaffold proteins Striatin and SG2NA assemble kinases and phosphatases into the signalling complexes called STRIPAK. Dysfunctional STRIPAKs cause cancer, cerebral cavernous malformations, etc. DJ-1, a sensor for oxidative stress, has long been associated with the Parkinson's disease, cancer, and immune disorders. SG2NA interacts with DJ-1 and Akt providing neuroprotection under oxidative stress. To dissect the role of SG2NA and DJ-1 in neuronal pathobiology, rat midbrain extracts were immunoprecipitated with SG2NA and sixty-three interacting proteins were identified. BN-PAGE followed by the LC-MS/MS showed 1030 comigrating proteins as the potential constituents of the multimeric complexes formed by SG2NA. Forty-three proteins were common between those identified by co-immunoprecipitation and the BN-PAGE. Co-immunoprecipitation with DJ-1 identified 179 interacting partners, of which forty-one also interact with SG2NA. Among those forty-one proteins immunoprecipitated with both SG2NA and DJ-1, thirty-nine comigrated with SG2NA in the BN-PAGE, and thus are bonafide constituents of the supramolecular assemblies comprising both DJ-1 and SG2NA. Among those thirty-nine proteins, seven are involved in mitochondrial oxidative phosphorylation. In rotenone-treated rats having Parkinson's like symptoms, the levels of both SG2NA and DJ-1 increased in the mitochondria; and the association of SG2NA with the electron transport complexes enhanced. In the hemi-Parkinson's model, where the rats were injected with 6-OHDA into the midbrain, the occupancy of SG2NA and DJ-1 in the mitochondrial complexes also increased. Our study thus reveals a new family of potential STRIPAK assemblies involving both SG2NA and DJ-1, with key roles in protecting midbrain from the oxidative stress.

Diabetes-induced stimulation of the renin-angiotensin system in the rat brain cortex

Cerebrovascular disease is a threat to people with diabetes and hypertension. Diabetes can damage the brain by stimulating the renin-angiotensin system (RAS), leading to neurological deficits and brain strokes. Diabetes-induced components of the RAS, including angiotensin-converting enzyme (ACE), angiotensin-II (Ang-II), and angiotensin type 1 receptor (AT1R), have been linked to various neurological disorders in the brain. In this study, we investigated how diabetes and high blood pressure affected the regulation of these major RAS components in the frontal cortex of the rat brain. We dissected, homogenized, and processed the brain cortex tissues of control, streptozotocin-induced diabetic, spontaneously hypertensive (SHR), and streptozotocin-induced SHR rats for biochemical and Western blot analyses. We found that systolic blood pressure was elevated in SHR rats, but there was no significant difference between SHR and diabetic-SHR rats. In contrast to SHR rats, the heartbeat of diabetic SHR rats was low. Western blot analysis showed that the frontal cortexes of the brain expressed angiotensinogen, AT1R, and MAS receptor. There were no significant differences in angiotensinogen levels across the rat groups. However, the AT1R level was increased in diabetic and hypertensive rats compared to controls, whereas the MAS receptor was downregulated (p < 0.05). These findings suggest that RAS overactivation caused by diabetes may have negative consequences for the brain's cortex, leading to neurodegeneration and cognitive impairment.

Impact of in-utero electronic cigarette exposure on neonatal neuroinflammation, oxidative stress and mitochondrial function

Introduction: Despite the prevalence of the perception that electronic cigarettes (e-cig) are a safer alternative to tobacco smoke, growing concern about their potential toxic impact warrants adequate investigation focusing on special populations like maternal and pediatric groups. This study evaluated the consequences of maternal e-cig use on neonatal neuroinflammation, oxidative stress, and mitochondrial function in primary cultured neurons and postnatal day (PD) 7 and 90 brain. Methodology: Pregnant CD1 mice were exposed to e-cig vapor (2.4% nicotine) from gestational day 5 (E5) till PD7, and the primary neurons were isolated from pups at E16/17. Cellular total reactive oxygen species (ROS) and mitochondrial superoxide were measured in primary neurons using CM-H2DCFDA and Mitosox red, respectively. Mitochondrial function was assessed by Seahorse XF Cell Mitostress analysis. The level of pro-inflammatory cytokines was measured in primary neurons and PD7 and PD90 brains by RT-PCR and immunobead assay. Western blot analysis evaluated the expression of antioxidative markers (SOD-2, HO-1, NRF2, NQO1) and that of the proinflammatory modulator NF-κB. Results: Significantly higher level of total cellular ROS (p < 0.05) and mitochondrial superoxide (p < 0.01) was observed in prenatally e-cig-exposed primary neurons. We also observed significantly reduced antioxidative marker expression and increased proinflammatory modulator and cytokines expression in primary neurons and PD7 (p < 0.05) but not in PD90 postnatal brain. Conclusion: Our findings suggest that prenatal e-cig exposure induces postnatal neuroinflammation by promoting oxidative stress (OS), increasing cytokines' levels, and disrupting mitochondrial function. These damaging events can alter the fetal brain's immune functions, making such offspring more vulnerable to brain insults.

Blood-Brain Barrier Breakdown in Neuroinflammation: Current In Vitro Models

The blood-brain barrier, which is formed by tightly interconnected microvascular endothelial cells, separates the brain from the peripheral circulation. Together with other central nervous system-resident cell types, including pericytes and astrocytes, the blood-brain barrier forms the neurovascular unit. Upon neuroinflammation, this barrier becomes leaky, allowing molecules and cells to enter the brain and to potentially harm the tissue of the central nervous system. Despite the significance of animal models in research, they may not always adequately reflect human pathophysiology. Therefore, human models are needed. This review will provide an overview of the blood-brain barrier in terms of both health and disease. It will describe all key elements of the in vitro models and will explore how different compositions can be utilized to effectively model a variety of neuroinflammatory conditions. Furthermore, it will explore the existing types of models that are used in basic research to study the respective pathologies thus far.

Toll-like Receptors as Pro-Thrombotic Drivers in Viral Infections: A Narrative Review

Toll-like receptors (TLRs) have a critical role in the pathogenesis and disease course of viral infections. The induced pro-inflammatory responses result in the disturbance of the endovascular surface layer and impair vascular homeostasis. The injury of the vessel wall further promotes pro-thrombotic and pro-coagulatory processes, eventually leading to micro-vessel plugging and tissue necrosis. Moreover, TLRs have a direct role in the sensing of viruses and platelet activation. TLR-mediated upregulation of von Willebrand factor release and neutrophil, as well as macrophage extra-cellular trap formation, further contribute to (micro-) thrombotic processes during inflammation. The following review focuses on TLR signaling pathways of TLRs expressed in humans provoking pro-thrombotic responses, which determine patient outcome during viral infections, especially in those with cardiovascular diseases.

Oxidative Stress in a Mother Consuming Alcohol during Pregnancy and in Her Newborn: A Case Report

Fetal alcohol spectrum disorder (FASD) is a set of conditions resulting from prenatal alcohol exposure (PAE). FASD is estimated to affect between 2% and 5% of people in the United States and Western Europe. The exact teratogenic mechanism of alcohol on fetal development is still unclear. Ethanol (EtOH) contributes to the malfunctioning of the neurological system in children exposed in utero by decreasing glutathione peroxidase action, with an increase in the production of reactive oxygen species (ROS), which causes oxidative stress. We report a case of a mother with declared alcohol abuse and cigarette smoking during pregnancy. By analyzing the ethyl glucuronide (EtG, a metabolite of alcohol) and the nicotine/cotinine in the mother's hair and meconium, we confirmed the alcohol and smoking abuse magnitude. We also found that the mother during pregnancy was a cocaine abuser. As a result, her newborn was diagnosed with fetal alcohol syndrome (FAS). At the time of the delivery, the mother, but not the newborn, had an elevation in oxidative stress. However, the infant, a few days later, displayed marked potentiation in oxidative stress. The clinical complexity of the events involving the infant was presented and discussed, underlining also the importance that for cases of FASD, it is crucial to have more intensive hospital monitoring and controls during the initial days.

Physical activity for cognitive health promotion: An overview of the underlying neurobiological mechanisms

Physical activity is one of the modifiable factors of cognitive decline and dementia with the strongest evidence. Although many influential reviews have illustrated the neurobiological mechanisms of the cognitive benefits of physical activity, none of them have linked the neurobiological mechanisms to normal exercise physiology to help the readers gain a more advanced, comprehensive understanding of the phenomenon. In this review, we address this issue and provide a synthesis of the literature by focusing on five most studied neurobiological mechanisms. We show that the body's adaptations to enhance exercise performance also benefit the brain and contribute to improved cognition. Specifically, these adaptations include, 1), the release of growth factors that are essential for the development and growth of neurons and for neurogenesis and angiogenesis, 2), the production of lactate that provides energy to the brain and is involved in the synthesis of glutamate and the maintenance of long-term potentiation, 3), the release of anti-inflammatory cytokines that reduce neuroinflammation, 4), the increase in mitochondrial biogenesis and antioxidant enzyme activity that reduce oxidative stress, and 5), the release of neurotransmitters such as dopamine and 5-HT that regulate neurogenesis and modulate cognition. We also discussed several issues relevant for prescribing physical activity, including what intensity and mode of physical activity brings the most cognitive benefits, based on their influence on the above five neurobiological mechanisms. We hope this review helps readers gain a general understanding of the state-of-the-art knowledge on the neurobiological mechanisms of the cognitive benefits of physical activity and guide them in designing new studies to further advance the field.

Psychomotor Performance after 30 h of Sleep Deprivation Combined with Exercise

Sleep deprivation (SD) usually impairs psychomotor performance, but most experiments are usually focused on sedentary conditions. The purpose of this study was to evaluate the influence of 30 h of complete SD combined with prolonged, moderate exercise (SDE) on human psychomotor performance. Eleven endurance-trained men accustomed to overnight exertion were tested twice: in well-slept and non-fatigued conditions (Control) and immediately after 30 h of SDE. They performed a multiple-choice reaction time test (MCRT) at rest and during each workload of the graded exercise test to volitional exhaustion. At rest, the MCRT was shorter after SDE than in the Control (300 ± 13 ms vs. 339 ± 11 ms, respectively, p < 0.05). During graded exercise, there were no significant differences in MCRT between groups, but the fastest reaction was observed at lower workloads after SDE (158 ± 7 W vs. 187 ± 11 W in Control, p < 0.05). The total number of missed reactions tended to be higher after SDE (8.4 ± 0.7 vs. 6.3 ± 0.8 in Control, p = 0.06). In conclusion, SDE is different from SD alone; however, well-trained men, accustomed to overnight exertion can maintain psychomotor abilities independently of the extent of central fatigue. Exercise can be used to enhance psychomotor performance in sleep-deprived subjects in whom special caution is required in order to avoid overload.

Sudden unexpected death in epilepsy is prevented by blocking postictal hypoxia

Epilepsy is at times a fatal disease. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of epilepsy-related mortality in people with intractable epilepsy and is defined by exclusion; non-accidental, non-toxicologic, and non-anatomic causes of death. While SUDEP often follows a bilateral tonic-clonic seizure, the mechanisms that ultimately lead to terminal apnea and then asystole remain elusive and there is a lack of preventative treatments. Based on the observation that discrete seizures lead to local and postictal vasoconstriction, resulting in hypoperfusion, hypoxia and behavioural disturbances in the forebrain we reasoned those similar mechanisms may play a role in SUDEP when seizures invade the brainstem. Here we tested this neurovascular-based hypothesis of SUDEP in awake non-anesthetized mice by pharmacologically preventing seizure-induced vasoconstriction, with cyclooxygenase-2 or L-type calcium channel antagonists. In both acute and chronic mouse models of seizure-induced premature mortality, ibuprofen and nicardipine extended life while systemic drug levels remained high enough to be effective. We also examined the potential role of spreading depolarization in the acute model of seizure-induced premature mortality. These data provide a proof-of-principle for the neurovascular hypothesis of SUDEP rather than spreading depolarization and the use of currently available drugs to prevent it.

Lipids at the Nexus between Cerebrovascular Disease and Vascular Dementia: The Impact of HDL-Cholesterol and Ceramides

Cerebrovascular diseases and the subsequent brain hypoperfusion are at the basis of vascular dementia. Dyslipidemia, marked by an increase in circulating levels of triglycerides and LDL-cholesterol and a parallel decrease in HDL-cholesterol, in turn, is pivotal in promoting atherosclerosis which represents a common feature of cardiovascular and cerebrovascular diseases. In this regard, HDL-cholesterol has traditionally been considered as being protective from a cardiovascular and a cerebrovascular prospective. However, emerging evidence suggests that their quality and functionality play a more prominent role than their circulating levels in shaping cardiovascular health and possibly cognitive function. Furthermore, the quality of lipids embedded in circulating lipoproteins represents another key discriminant in modulating cardiovascular disease, with ceramides being proposed as a novel risk factor for atherosclerosis. This review highlights the role of HDL lipoprotein and ceramides in cerebrovascular diseases and the repercussion on vascular dementia. Additionally, the manuscript provides an up-to-date picture of the impact of saturated and omega-3 fatty acids on HDL circulating levels, functionality and ceramide metabolism.

Advantages and Potential Benefits of Using Organoids in Nanotoxicology

Organoids are microtissues that recapitulate the complex structural organization and functions of tissues and organs. Nanoparticles have several specific properties that must be considered when replacing animal models with in vitro studies, such as the formation of a protein corona, accumulation, ability to overcome tissue barriers, and different severities of toxic effects in different cell types. An increase in the number of articles on toxicology research using organoid models is related to an increase in publications on organoids in general but is not related to toxicology-based publications. We demonstrate how the quantitative assessment of toxic changes in the structure of organoids and the state of their cell collections provide more valuable results for toxicological research and provide examples of research methods. The impact of the tested materials on organoids and their differences are also discussed. In conclusion, we highlight the main challenges, the solution of which will allow researchers to approach the replacement of in vivo research with in vitro research: biobanking and standardization of the structural characterization of organoids, and the development of effective screening imaging techniques for 3D organoid cell organization.

Antioxidant and Antithrombotic Activities of Kenaf Seed (Hibiscus cannabinus) Coat Ethanol Extract in Sprague Dawley Rats

Oxidative stress has been implicated in deadly lifestyle diseases, and antioxidants from plant sources are the primary option in the treatment regime. Kenaf seeds are the storehouse of potential natural antioxidant phytoconstituents. Perhaps, none of the studies documented the phytoconstituents and their antioxidant potential from Kenaf seed coat so far. Thus, the current study focuses on exploring the protective effect of Kenaf Seed Coat Ethanol Extract (KSCEE) against sodium nitrite and diclofenac-induced oxidative stress in vitro (red blood cell and platelets model) and in vivo (female Sprague Dawely rat's model) along with the antithrombotic activity. The infrared spectrophotometry data showed the heterogeneous functional groups (CH, OH, C = C, C = C-C) and aromatic rings. Reverse phase high-performance liquid chromatography and gas chromatography-mass spectrometry chromatogram of KSCEE also evidenced the presence of several phytochemicals. KSCEE displayed about 76% of DPPH scavenging activity with an IC₅₀ value of 34.94 µg/ml. KSCEE significantly (***p < 0.001) normalized the stress markers such as lipid peroxidation, protein carbonyl content, superoxide dismutase, and catalase in sodium nitrite and diclofenac-induced oxidative stress in RBC, platelets, liver, kidney, and small intestine, respectively. Furthermore, KSCEE was found to protect the diclofenac-induced tissue destruction of the liver, kidney, and small intestine obtained from seven groups of female Sprague Dawely rats. KSCEE delayed the clotting time of platelet-rich plasma and platelet-poor plasma and activated partial thromboplastin time, suggesting its anticoagulant property. In addition, KSCEE also exhibited antiplatelet activity by inhibiting both adenosine diphosphate and epinephrine-induced platelet aggregation. In conclusion, KSCEE ameliorates the sodium nitrite and diclofenac-induced oxidative stress in red blood cells, platelets, and experimental animals along with antithrombotic properties.

Long-term administration of CU06-1004 ameliorates cerebrovascular aging and BBB injury in aging mouse model

BACKGROUND

Age-related changes in the cerebrovasculature, including blood-brain barrier (BBB) disruption and vascular dementia, are emerging as potential risks for many neurodegenerative diseases. Therefore, the endothelial cells that constitute the cerebrovasculature may play key roles in preventing brain injury. Our previous study showed that CU06-1004, an endothelial cell dysfunction blocker, prevented vascular leakage, enhanced vascular integrity in ischemic reperfusion injury, and promoted the normalization of tumor vasculature. Here, we evaluated the effects of CU06-1004 on age-related cerebrovascular functional decline in the aged mouse brain.

RESULTS

In this study, we investigated the protective effects of CU06-1004 against oxidative stress-induced damage in human brain microvascular endothelial cells (HBMECs). HBMECs were treated with hydrogen peroxide (H₂O₂) to establish an oxidative stress-induced model of cellular injury. Compared with H₂O₂ treatment alone, pretreatment of HBMECs with CU06-1004 considerably reduced oxidative stress-induced cytotoxicity, reactive oxygen species generation, senescence-associated β-galactosidase activity, senescence marker expression, and the expression levels of inflammatory proteins. Based on the observed cytoprotective effects of CU06-1004 in HBMECs, we examined whether CU06-1004 displayed protective effects against cerebrovascular aging in mice. Long-term administration of CU06-1004 alleviated age-associated cerebral microvascular rarefaction and cerebrovascular senescence in the aged mouse brain. CU06-1004 supplementation also reduced the extravasation of plasma IgG by improving BBB integrity in the aged mouse brain, associated with reductions in neuronal injury. A series of behavioral tests also revealed improved motor and cognitive functions in aged mice that received long-term CU06-1004 administration.

CONCLUSIONS

These findings suggest that CU06-1004 may represent a promising therapeutic approach for delaying age-related cerebrovascular impairment and improving cognitive function in old age.

Accelerated amyloid angiopathy and related vascular alterations in a mixed murine model of Alzheimer´s disease and type two diabetes

BACKGROUND

While aging is the main risk factor for Alzheimer´s disease (AD), emerging evidence suggests that metabolic alterations such as type 2 diabetes (T2D) are also major contributors. Indeed, several studies have described a close relationship between AD and T2D with clinical evidence showing that both diseases coexist. A hallmark pathological event in AD is amyloid-β (Aβ) deposition in the brain as either amyloid plaques or around leptomeningeal and cortical arterioles, thus constituting cerebral amyloid angiopathy (CAA). CAA is observed in 85-95% of autopsy cases with AD and it contributes to AD pathology by limiting perivascular drainage of Aβ.

METHODS

To further explore these alterations when AD and T2D coexist, we have used in vivo multiphoton microscopy to analyze over time the Aβ deposition in the form of plaques and CAA in a relevant model of AD (APPswe/PS1dE9) combined with T2D (db/db). We have simultaneously assessed the effects of high-fat diet-induced prediabetes in AD mice. Since both plaques and CAA are implicated in oxidative-stress mediated vascular damage in the brain, as well as in the activation of matrix metalloproteinases (MMP), we have also analyzed oxidative stress by Amplex Red oxidation, MMP activity by DQ™ Gelatin, and vascular functionality.

RESULTS

We found that prediabetes accelerates amyloid plaque and CAA deposition, suggesting that initial metabolic alterations may directly affect AD pathology. T2D significantly affects vascular pathology and CAA deposition, which is increased in AD-T2D mice, suggesting that T2D favors vascular accumulation of Aβ. Moreover, T2D synergistically contributes to increase CAA mediated oxidative stress and MMP activation, affecting red blood cell velocity.

CONCLUSIONS

Our data support the cross-talk between metabolic disease and Aβ deposition that affects vascular integrity, ultimately contributing to AD pathology and related functional changes in the brain microvasculature.

Potential Protective Mechanisms of S-equol, a Metabolite of Soy Isoflavone by the Gut Microbiome, on Cognitive Decline and Dementia

S-equol, a metabolite of soy isoflavone daidzein transformed by the gut microbiome, is the most biologically potent among all soy isoflavones and their metabolites. Soy isoflavones are phytoestrogens and exert their actions through estrogen receptor-β. Epidemiological studies in East Asia, where soy isoflavones are regularly consumed, show that dietary isoflavone intake is inversely associated with cognitive decline and dementia; however, randomized controlled trials of soy isoflavones in Western countries did not generally show their cognitive benefit. The discrepant results may be attributed to S-equol production capability; after consuming soy isoflavones, 40-70% of East Asians produce S-equol, whereas 20-30% of Westerners do. Recent observational and clinical studies in Japan show that S-equol but not soy isoflavones is inversely associated with multiple vascular pathologies, contributing to cognitive impairment and dementia, including arterial stiffness and white matter lesion volume. S-equol has better permeability to the blood-brain barrier than soy isoflavones, although their affinity to estrogen receptor-β is similar. S-equol is also the most potent antioxidant among all known soy isoflavones. Although S-equol is available as a dietary supplement, no long-term trials in humans have examined the effect of S-equol supplementation on arterial stiffness, cerebrovascular disease, cognitive decline, or dementia.

Impact of the Renin-Angiotensin System on the Pathogeny and Pharmacotherapeutics of Neurodegenerative Diseases

Brain neurodegenerative diseases (BND) are debilitating conditions that are especially characteristic of a certain period of life and considered major threats to human health. Current treatments are limited, meaning that there is a challenge in developing new options that can efficiently tackle the different components and pathophysiological processes of these conditions. The renin-angiotensin-aldosterone system (RAS) is an endocrine axis with important peripheral physiological functions such as blood pressure and cardiovascular homeostasis, as well as water and sodium balance and systemic vascular resistance-functions which are well-documented. However, recent work has highlighted the paracrine and autocrine functions of RAS in different tissues, including the central nervous system (CNS). It is known that RAS hyperactivation has pro-inflammatory and pro-oxidant effects, thus suggesting that its pharmacological modulation could be used in the management of these conditions. The present paper underlines the involvement of RAS and its components in the pathophysiology of BNDs such as Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS), Huntington's disease (HD), motor neuron disease (MND), and prion disease (PRD), as well as the identification of drugs and pharmacologically active substances that act upon RAS, which could alleviate their symptomatology or evolution, and thus, contribute to novel therapeutic approaches.

Role of NADPH Oxidases in Blood-Brain Barrier Disruption and Ischemic Stroke

NADPH oxidases (Nox) are one of the main sources of reactive oxygen species (ROS) in the central nervous system (CNS). While these enzymes have been shown to be involved in physiological regulation of cerebral vascular tone, excessive ROS produced by Nox1-5 play a critical role in blood–brain barrier (BBB) dysfunction in numerous neuropathologies. Nox-derived ROS have been implicated in mediating matrix metalloprotease (MMP) activation, downregulation of junctional complexes between adjacent brain endothelial cells and brain endothelial cell apoptosis, leading to brain microvascular endothelial barrier dysfunction and consequently, increases in BBB permeability. In this review, we will highlight recent findings on the role played by these enzymes in BBB disruption induced by ischemic stroke.

Hispolon alleviates oxidative damage by stimulating the Nrf2 signaling pathway in PC12 cells

Natural products derived from the daily diet are garnering increasing attention for neurodegenerative disease (ND) treatment. Hispolon (His), a small molecule from Phellinus linteus, has been reported to have various pharmacological activities. Here, we evaluated its protective effect on a neuron-like rat pheochromocytoma cell line (PC12). Results showed that His could restore cell death induced by oxidative damage. Nuclear factor-erythroid 2 (NF-E2)-related factor 2 (Nrf2) plays a significant role in maintaining cellular redox homeostasis. After treatment with His, some Nrf2-governed antioxidant genes were upregulated in a dose-dependent manner. However, the protective effect of His on PC12 cells was easily terminated by Nrf2 knockdown, demonstrating that Nrf2 is a critical component in this cytoprotective process. Taken together, our study showed that His was not only an effective activator of Nrf2 but also a promising candidate for ND treatment.

Antioxidant Effects of DPP-4 Inhibitors in Early Stages of Experimental Diabetic Retinopathy

Hyperglycemia-induced oxidative stress plays a key role in the impairment of the retinal neurovascular unit, an early event in the pathogenesis of DR. The aim of this study was to assess the antioxidant properties of topical administration (eye drops) of sitagliptin in the diabetic retina. For this purpose, db/db mice received sitagliptin or vehicle eye drops twice per day for two weeks. Age-matched db/+ mice were used as the control group. We evaluated retinal mRNA (RT-PCR) and protein levels (Western blotting and immunohistochemistry) of different components from both the antioxidant system (NRF2, CAT, GPX, GR, CuZnSOD, and MnSOD) and the prooxidant machinery (PKC and TXNIP). We also studied superoxide levels (dihydroethidium staining) and oxidative damage to DNA/RNA (8-hydroxyguanosine immunostaining) and proteins (nitrotyrosine immunostaining). Finally, NF-кB translocation and IL-1β production were assessed through Western blotting and/or immunohistochemistry. We found that sitagliptin protected against diabetes-induced oxidative stress by reducing superoxide, TXNIP, PKC, and DNA/RNA/protein oxidative damage, and it prevented the downregulation of NRF2 and antioxidant enzymes, with the exception of catalase. Sitagliptin also exerted anti-inflammatory effects, avoiding both NF-кB translocation and IL-1β production. Sitagliptin prevents the diabetes-induced imbalance between ROS production and antioxidant defenses that occurs in diabetic retinas.

Blocking of P2X7r Reduces Mitochondrial Stress Induced by Alcohol and Electronic Cigarette Exposure in Brain Microvascular Endothelial Cells

Studies in both humans and animal models demonstrated that chronic alcohol/e-cigarette (e-Cig) exposure affects mitochondrial function and impairs barrier function in brain microvascular endothelial cells (BMVECs). Identification of the signaling pathways by which chronic alcohol/e-Cig exposure induces mitochondrial damage in BMVEC is vital for protection of the blood-brain barrier (BBB). To address the issue, we treated human BMVEC [hBMVECs (D3 cell-line)] with ethanol (ETH) [100 mM], acetaldehyde (ALD) [100 μM], or e-cigarette (e-Cig) [35 ng/mL of 1.8% or 0% nicotine] conditioned medium and showed reduced mitochondrial oxidative phosphorylation (OXPHOS) measured by a Seahorse analyzer. Seahorse data were further complemented with the expression of mitochondrial OXPHOS proteins detected by Western blots. We also observed cytosolic escape of ATP and its extracellular release due to the disruption of mitochondrial membrane potential caused by ETH, ALD, or 1.8% e-Cig exposure. Moreover ETH, ALD, or 1.8% e-Cig treatment resulted in elevated purinergic P2X7r and TRPV1 channel gene expression, measured using qPCR. We also demonstrated the protective role of P2X7r antagonist A804598 (10 μM) in restoring mitochondrial oxidative phosphorylation levels and preventing extracellular ATP release. In a BBB functional assay using trans-endothelial electrical resistance, we showed that blocking the P2X7r channel enhanced barrier function. In summary, we identified the potential common pathways of mitochondrial injury caused by ETH, ALD, and 1.8% e-Cig which allow new protective interventions. We are further investigating the potential link between P2X7 regulatory pathways and mitochondrial health.

GSH-AuNP anti-oxidative stress, ER stress and mitochondrial dysfunction in amyloid-beta peptide-treated human neural stem cells

Amyloid-beta (Aβ) peptides have a role in the pathogenesis of Alzheimer's disease (AD) and are thought to promote oxidative stress, endoplasmic reticulum (ER) stress and mitochondrial deficiency, causing neuronal loss in the AD brain. The potential applications of glutathione conjugated gold nanoparticles (GSH-AuNPs) suggest they might have therapeutic value. Several studies have demonstrated that the effects of nanoparticles could provide protective roles in AD. Here, we showed that GSH-AuNPs mediate the viability of human neural stem cells (hNSCs) with Aβ, which was correlated with decreased caspase 3 and caspase 9. Importantly, hNSCs co-treated with GSH-AuNPs were significantly protected from Aβ-induced oxidative stress, as detected using the DCFH-DA, DHE, and MitoSOX staining assays. Furthermore, hNSCs co-treated with GSH-AuNPs were significantly protected from the Aβ-induced reduction in the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and Nrf2 downstream antioxidant target genes (SOD-1, SOD-2, Gpx, Catalase, and HO-1). In addition, GSH-AuNPs rescued the expression levels of ER stress-associated genes (Bip, CHOP, and ASK1) in Aβ-treated hNSCs. GSH-AuNPs normalized ER calcium and mitochondrial cytochrome c homeostasis in Aβ-treated hNSCs. Furthermore, treatment with GSH-AuNPs restored the levels of ATP, D-loop, mitochondrial mass, basal respiration, ATP-linked reparation, maximal respiration capacity, COX activity, mitochondrial membrane potential, and mitochondrial genes (PGC1α, NRF-1 and Tfam) in Aβ-treated hNSCs. Taken together, these findings extend our understanding of the protective effects of GSH-AuNPs against oxidative stress, ER stress and mitochondrial dysfunction in hNSCs with Aβ.

Variation within the visually evoked neurovascular coupling response of the posterior cerebral artery is not influenced by age or sex

Neurovascular coupling (NVC) is the temporal and spatial coordination between local neuronal activity and regional cerebral blood flow. The literature is unsettled on whether age and/or sex affect NVC, which may relate to differences in methodology and the quantification of NVC in small sample-sized studies. The aim of this study was to 1) determine the relative and combined contribution of age and sex to the variation observed across several distinct NVC metrics (n = 125, 21–66 yr; 41 males) and 2) present an approach for the comprehensive systematic assessment of the NVC response using transcranial Doppler ultrasound. NVC was measured as the relative change from baseline (absolute and percent change) assessing peak, mean, and total area under the curve (tAUC) of cerebral blood velocity through the posterior cerebral artery (PCAv) during intermittent photic stimulation. In addition, the NVC waveform was compartmentalized into distinct regions, acute (0–9 s), mid (10–19 s), and late (20–30 s), following the onset of photic stimulation. Hierarchical multiple regression modeling was used to determine the extent of variation within each NVC metric attributable to demographic differences in age and sex. After controlling for differences in baseline PCAv, the R² data suggest that 1.6%, 6.1%, 1.1%, 3.4%, 2.5%, and 4.2% of the variance observed within mean, peak, tAUC, acute, mid, and late response magnitude is attributable to the combination of age and sex. Our study reveals that variability in NVC response magnitude is independent of age and sex in healthy human participants, aged 21–66 yr.

NEW & NOTEWORTHY We assessed the variability within the neurovascular coupling response attributable to age and sex (n = 125, 21–66 yr; 41 male). Based on the assessment of posterior cerebral artery responses to visual stimulation, 0%–6% of the variance observed within several metrics of NVC response magnitude are attributable to the combination of age and sex. Therefore, observed differences between age groups and/or sexes are likely a result of other physiological factors.

Risk Factors from Pregnancy to Adulthood in Multiple Sclerosis Outcome

Multiple sclerosis (MS) is an autoimmune disease characterized by a robust inflammatory response against myelin sheath antigens, which causes astrocyte and microglial activation and demyelination of the central nervous system (CNS). Multiple genetic predispositions and environmental factors are known to influence the immune response in autoimmune diseases, such as MS, and in the experimental autoimmune encephalomyelitis (EAE) model. Although the predisposition to suffer from MS seems to be a multifactorial process, a highly sensitive period is pregnancy due to factors that alter the development and differentiation of the CNS and the immune system, which increases the offspring’s susceptibility to develop MS. In this regard, there is evidence that thyroid hormone deficiency during gestation, such as hypothyroidism or hypothyroxinemia, may increase susceptibility to autoimmune diseases such as MS. In this review, we discuss the relevance of the gestational period for the development of MS in adulthood.

Subclinical cognitive deficits are associated with reduced cerebrovascular response to visual stimulation in mid-sixties men

Reduced cerebrovascular response to neuronal activation is observed in patients with neurodegenerative disease. In the present study, we examined the correlation between reduced cerebrovascular response to visual activation (ΔCBF_Vis.Act) and subclinical cognitive deficits in a human population of mid-sixties individuals without neurodegenerative disease. Such a correlation would suggest that impaired cerebrovascular function occurs before overt neurodegenerative disease. A total of 187 subjects (age 64-67 years) of the Metropolit Danish Male Birth Cohort participated in the study. ΔCBF_Vis.Act was measured using arterial spin labelling (ASL) MRI. ΔCBF_Vis.Act correlated positively with cognitive performance in: Global cognition (p = 0.046), paired associative memory (p = 0.025), spatial recognition (p = 0.026), planning (p = 0.016), simple processing speed (p < 0.01), and with highly significant correlations with current intelligence (p < 10^-5), and more complex processing speed (p < 10^-3), the latter two explaining approximately 11-13% of the variance. Reduced ΔCBF_Vis.Act was independent of brain atrophy. Our findings suggest that inhibited cerebrovascular response to neuronal activation is an early deficit in the ageing brain and associated with subclinical cognitive deficits. Cerebrovascular dysfunction could be an early sign of a trajectory pointing towards the development of neurodegenerative disease. Future efforts should elucidate if maintenance of a healthy cerebrovascular function can protect against the development of dementia.

The amyloid peptide β disrupts intercellular junctions and increases endothelial permeability in a NADPH oxidase 1-dependent manner

Alzheimer's disease is the most common form of dementia and is associated with the accumulation of amyloid peptide β in the brain parenchyma. Vascular damage and microvascular thrombosis contribute to the neuronal degeneration and the loss of brain function typical of this disease. In this study, we utilised a murine model of Alzheimer's disease to evaluate the neurovascular effects of this disease. Upon detection of an increase in the phosphorylation of the endothelial surface receptor VE-cadherin, we focused our attention on endothelial cells and utilised two types of human endothelial cells cultured in vitro: 1) human umbilical vein endothelial cells (HUVECs) and 2) human brain microvascular endothelial cells (hBMECs). Using an electrical current impedance system (ECIS) and FITC-albumin permeability assays, we discovered that the treatment of human endothelial cells with amyloid peptide β causes a loss in their barrier function, which is oxidative stress-dependent and similarly to our observation in mouse brain associates with VE-cadherin phosphorylation. The activation of the superoxide anion-generating enzyme NADPH oxidase 1 is responsible for the oxidative stress that leads to the disruption of barrier function in human endothelial cells in vitro. In summary, we have identified a novel molecular mechanism explaining how the accumulation of amyloid peptide β in the brain parenchyma may induce the loss of neurovascular barrier function, which has been observed in patients. Neurovascular leakiness plays an important role in brain inflammation and neuronal degeneration driving the progression of the Alzheimer's disease. Therefore, this study provides a novel and promising target for the development of a pharmacological treatment to protect neurovascular function and reduce the progression of the neurodegeneration in Alzheimer's patients.

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Amyloid peptide β induces oxidative changes in mouse hippocampus.

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The endothelial barrier function is impaired by amyloid peptide β.

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Oxidative stress is critical for the increase in endothelial monolayer permeability.

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NADPH oxidase 1 mediates the endothelial barrier damage caused by amyloid peptide β.

Effects of acute and chronic oxidative stress on the blood-brain barrier in 2D and 3D in vitro models

Oxidative stress is a shared pathology of neurodegenerative disease and brain injuries, and is derived from perturbations to normal cell processes by aging or environmental factors such as UV exposure and air pollution. As oxidative cues are often present in systemic circulation, the blood-brain barrier (BBB) plays a key role in mediating the effect of these cues on brain dysfunction. Therefore, oxidative damage and disruption of the BBB is an emergent focus of neurodegenerative disease etiology and progression. We assessed barrier dysfunction in response to chronic and acute oxidative stress in 2D and 3D in vitro models of the BBB with human iPSC-derived brain microvascular endothelial-like cells (iBMECs). We first established doses of hydrogen peroxide to induce chronic damage (modeling aging and neurodegenerative disease) and acute damage (modeling the response to traumatic brain injury) by assessing barrier function via transendothelial electrical resistance in 2D iBMEC monolayers and permeability and monolayer integrity in 3D tissue-engineered iBMEC microvessels. Following application of these chronic and acute doses in our in vitro models, we found local, discrete structural changes were the most prevalent responses (rather than global barrier loss). Additionally, we validated unique functional changes in response to oxidative stress, including dysfunctional cell turnover dynamics and immune cell adhesion that were consistent with changes in gene expression.

Intertwined Relation between the Endoplasmic Reticulum and Mitochondria in Ischemic Stroke

In ischemic stroke (IS), accumulation of the misfolded proteins in the endoplasmic reticulum (ER) and mitochondria-induced oxidative stress (OS) has been identified as the indispensable inducers of secondary brain injury. With the increasing recognition of an association between ER stress and OS with ischemic stroke and with the improved understanding of the underlying molecular mechanism, novel targets for drug therapy and new strategies for therapeutic interventions are surfacing. This review discusses the molecular mechanism underlying ER stress and OS response as both causes and consequences of ischemic stroke. We also summarize the latest advances in understanding the importance of ER stress and OS in the pathogenesis of ischemic stroke and discuss potential strategies and clinical trials explicitly aiming to restore mitochondria and ER dynamics after IS.

Antioxidant Polyphenols of Antirhea borbonica Medicinal Plant and Caffeic Acid Reduce Cerebrovascular, Inflammatory and Metabolic Disorders Aggravated by High-Fat Diet-Induced Obesity in a Mouse Model of Stroke

Metabolic disorders related to obesity and type 2 diabetes are associated with aggravated cerebrovascular damages during stroke. In particular, hyperglycemia alters redox and inflammatory status, leading to cerebral endothelial cell dysfunction, blood–brain barrier (BBB) disruption and brain homeostasis loss. Polyphenols constitute the most abundant dietary antioxidants and exert anti-inflammatory effects that may improve cerebrovascular complications in stroke. This study evaluated the effects of the characterized polyphenol-rich extract of Antirhea borbonica medicinal plant and its major constituent caffeic acid on a high-fat diet (HFD)-induced obesity mouse model during ischemic stroke, and murine bEnd3 cerebral endothelial cells in high glucose condition. In vivo, polyphenols administered by oral gavage for 12 weeks attenuated insulin resistance, hyperglycemia, hyperinsulinemia and dyslipidemia caused by HFD-induced obesity. Polyphenols limited brain infarct, hemorrhagic transformation and BBB disruption aggravated by obesity during stroke. Polyphenols exhibited anti-inflammatory and antioxidant properties by reducing IL-1β, IL-6, MCP-1, TNF-α and Nrf2 overproduction as well as total SOD activity elevation at the cerebral or peripheral levels in obese mice. In vitro, polyphenols decreased MMP-2 activity that correlated with MCP-1 secretion and ROS intracellular levels in hyperglycemic condition. Protective effects of polyphenols were linked to their bioavailability with evidence for circulating metabolites including caffeic acid, quercetin and hippuric acid. Altogether, these findings show that antioxidant polyphenols reduced cerebrovascular, inflammatory and metabolic disorders aggravated by obesity in a mouse model of stroke. It will be relevant to assess polyphenol-based strategies to improve the clinical consequences of stroke in the context of obesity and diabetes.

RGS5 Protein Deficiency Differentially Influences Blood Pressure, Vascular and Behavioral Effects in Aged Male Mice

ABSTRACT

Aging and elevated activity of the renin-angiotensin-system (RAS) are associated with hypertension, vascular and emotional behavioral abnormalities, like anxiety and depression. Many actions of the main effector hormone of the RAS, angiotensin II (Ang II), are mediated by Ang II type 1 receptor whose activity is modulated by the regulator of G-protein signaling 5 (RGS5) protein. We assessed the role of RGS5 on blood pressure, vascular and emotional behavioral outcomes in aged male mice in the presence and absence of chronically elevated Ang II levels. We used aged (∼21 month old) male RGS5-deficient (RGS5-/-) and wild-type (RGS5+/+) mice treated with vehicle (saline) or Ang II (1 mg/kg/d for 21 days). RGS5 deficiency increased baseline systolic blood pressure (SBP), and cerebral vascular superoxide levels in the presence of chronically elevated Ang II levels, suggesting that RGS5 deficiency leads to elevated blood pressure and deleterious cerebral vascular outcomes in aged mice. RGS5 deletion had no effect on Ang II-induced increases in SBP. Chronically elevated Ang II levels increased spontaneous locomotor activity in RGS5+/+, but not RGS5-/- mice. RGS5 deficiency and Ang II treatment had no effect on anxiety- and depression-like behavior. This is the first study to assess the effects of deficiency of an RGS protein in the vasculature or on emotional behavioral outcomes in aged mice. We report that RGS5 has protective effects on blood pressure and the cerebral vasculature in aged mice. Clinically, these data suggest that RAS blockers may significantly reduce cerebrovascular disease risk in aged males lacking RGS5.