A brief overview of a mouse model of cerebral hypoperfusion by bilateral carotid artery stenosis

The Bidirectional Role of Hypoxia-Inducible Factor 1 Alpha in Vascular Dementia Caused by Chronic Cerebral Hypoperfusion

Chronic cerebral hypoperfusion (CCH) is a critical indicator of cognitive impairment and dementia, especially vascular dementia. Cerebral blood flow disturbance alters the properties of neurons and glial cells as a result of a deficit in energy sources. Hypoxia-inducible factor 1 alpha (HIF- 1α) is a transcription factor that controls gene activity in response to low oxygen levels. It regulates a complex network of cellular adaptations to improve oxygenation, metabolic reprogramming, and cell survival in hypoxic situations. However, recent research suggests that HIF- 1α plays a role not only in neuroprotection but also in brain injury. It is therefore critical to fully comprehend the mechanisms behind these disorders. This review highlights the dual role of HIF- 1α in CCH-induced VaD. Initially, HIF- 1α provides a neuroprotection by promoting angiogenesis through vascular endothelial growth factor (VEGF) signaling. However, prolonged activation can detrimentally effects, including oxidative stress, neuroinflammation, blood-brain barrier dysfunction, and cognitive impairment. Evidence suggests that HIF- 1α exerts its protective effects in acute ischemic/hypoxic-induced VaD through pathways such as PI3 K/AKT/mTOR and MAPK/p-c-Jun signaling. However, its dysregulation in chronic stages of CCH contributes to cognitive decline and disease progression. Understanding the complex role of HIF- 1α and its interactions with other molecular pathways is crucial for developing effective therapeutic strategies. Therefore, an informed, in-depth discussion of its involvement in these pathologic processes is necessary, as a precise contribution of HIF- 1α to CCH-induced VaD remains to be established and requires further investigation.

Salidroside attenuates cognitive deficits induced by chronic cerebral hypoperfusion via modulating microglial phenotypic transformation in mice

BACKGROUND

Chronic cerebral hypoperfusion (CCH) is a significant contributor to vascular cognitive impairment (VCI), often linked to cortical and hippocampal damage. This study investigates the therapeutic potential of salidroside (SLDS) in mitigating CCH-induced brain injury by modulating microglial activation and inflammatory responses.

METHODS

We established a CCH model in mice using the 0.16/0.18 mm bilateral common carotid artery stenosis (BCAS) procedure. We assessed cerebral blood flow (CBF) via laser speckle contrast imaging, while neuropathology was evaluated through Nissl staining and immunofluorescence (IF) experiments. Cognitive deficits were measured using the Morris water maze test. Neuronal apoptosis and neuroinflammation were examined through IF, ELISA, and qRT-PCR.

RESULTS

BCAS-induced hypoperfusion resulted in a marked reduction in CBF, increased neuronal apoptosis, and significant cognitive deficits. SLDS treatment effectively countered these effects by shifting microglial polarization from a pro-inflammatory M1 phenotype to an anti-inflammatory M2 phenotype, reducing pro-inflammatory cytokine levels, and enhancing neuronal survival.

CONCLUSION

SLDS demonstrates strong neuroprotective potential against CCH-induced brain injury by reducing inflammation and preventing neuronal apoptosis. These findings highlight the promise of SLDS as a therapeutic agent for chronic cerebrovascular disorders, warranting further investigation into its molecular mechanisms and clinical applicability.

Oxidative stress and chronic cerebral hypoperfusion: An overview from preclinical rodent models

Chronic cerebral hypoperfusion (CCH) is an important clinical condition characterized by a prolonged reduction in cerebral blood flow that contributes to several neurodegenerative diseases, including vascular dementia and Alzheimer's disease. A number of rodent models of CCH have been developed that mimic the human pathological conditions of reduced cerebral perfusion. These models have been instrumental in elucidating the molecular and cellular mechanisms involved in CCH-induced brain damage. Oxidative stress is induced by perturbations in cellular pathways caused by CCH, including mitochondrial dysfunction, ion pump dysfunction, and adenosine triphosphate (ATP) depletion. The deleterious stress leads to the accumulation of reactive oxygen species (ROS) and exacerbates damage to neuronal structures, significantly impairing cognitive function. Among the various therapeutic strategies being evaluated, edaravone, a potent antioxidant, is emerging as a promising drug due to its neuroprotective properties against oxidative stress. Initially approved for use in ischemic stroke, research using rodent CCH models has shown that edaravone has significant efficacy in scavenging free radicals and ameliorating oxidative stress-induced neuronal damage under CCH conditions. This mini-review summarizes the current literature on the rodent models of CCH and then discusses the therapeutic potential of edaravone to reduce neuronal and vascular damage caused by CCH-induced oxidative stress.

Prolonged Chronic Cerebral Hypoperfusion Does not Exacerbate Tau Pathology in a Tauopathy Mouse Model

BACKGROUND

Several preclinical studies have reported elevated levels of tau following the induction of chronic cerebral hypoperfusion (CCH) in Alzheimer's disease mouse models. The objective of this study was to first induce CCH in a mouse model of tauopathy over an extended period of up to 6 months and to subsequently investigate the effects of CCH on tau accumulation and alterations in the transcriptome.

METHODS

Three-month-old P301S tauopathy mice were randomly allocated to either a Sham or CCH group. The common carotid arteries (CCAs) of the CCH group were bilaterally implanted using 0.75-mm inner diameter ameroid constrictors. Prior to surgery, Doppler ultrasound imaging was acquired, with follow-up imaging at 1, 3, and 6 months postoperatively. Brain tissue samples were obtained, and hemispheres were dissected and divided for separate analysis.

RESULT

No significant differences in phosphorylated and total tau protein levels were found in either Sham or CCH left cortical hemispheres or hippocampal lysates. Immunohistochemical staining of phosphorylated tau in the right hemisphere revealed similar findings. Compared with the Sham group, transcriptomic deconvolution revealed a significant reduction of memory B cells in the CCH group (p = 0.029).

CONCLUSION

To clarify the effects of chronic hypoperfusion on tau pathology, more than one surgical method of hypoperfusion should be used in future studies.

Edaravone dexborneol alleviates pericyte-mediated fibrosis depositing extracellular matrix through TGF-β1/IL-11 in cerebral small vessel disease

BACKGROUND

Chronic cerebral hypoperfusion (CCH) is a critical pathophysiological mechanism underlying cerebral small vessel disease (CSVD). Accumulating evidence have demonstrated that resident pericytes and deposit extracellular matrix (ECM) and play a key role in mediating fibrosis in hypoxic changes. Edaravone dexborneol (EDB) is known to target multiple pathways involved in fibrosis.

METHODS

We constructed the CCH mouse models that were subjected to either PBS or EDB at different concentrations. Measures of cognitive function, neuronal damage, white matter lesion (WML), the fibrous profiles of pericytes and ECM protein were investigated to assess the effect of EDB. RNA sequencing of OGD in pericytes was performed to identify a key signaling pathway.

RESULTS

We observed that both medium and high concentrations of EDB could ameliorate CCH-induced cognitive impairment and emotional disorders. Neuronal damage in cortical layer and hippocampus and WML in corpus callosum were improved by EDB, which was consistent with the tends of fibrous pericytes and ECM proteins in these regions. RNA sequencing suggested that TGF-β1/IL-11 plays an important role in mechanism of pericytes fibrosis. Subsequently, the results of sequencing were confirmed in both cellular and mouse model.

CONCLUSIONS

Our findings reveal the role of pericyte-mediated fibrosis in depositing ECM in the pathogenesis of CSVD. EDB could improve symptoms and the underlying pathogenesis of CCH mice and decrease the expression of the fibrous profiles of pericytes and ECM proteins, which may be regulated by TGF-β1/ IL-11. EDB treatment, targeting pericytes fibrosis, may be a novel therapeutic strategy for CSVD.

Cerebral hypoperfusion reduces tau accumulation

OBJECTIVE

Alzheimer's disease (AD) often coexists with cerebrovascular diseases. However, the impact of cerebrovascular diseases such as stroke on AD pathology remains poorly understood.

METHODS

This study examines the correlation between cerebrovascular diseases and AD pathology. The research was carried out using clinical and neuropathological data collected from the National Alzheimer's Coordinating Center (NACC) database and an animal model in which bilateral common carotid artery stenosis surgery was performed, following the injection of tau seeds into the brains of wild-type mice.

RESULTS

Analysis of the NACC database suggests that clinical stroke history and lacunar infarcts are associated with lower neurofibrillary tangle pathology. An animal model demonstrates that chronic cerebral hypoperfusion reduces tau pathology, which was observed in not only neurons but also astrocytes, microglia, and oligodendrocytes. Furthermore, we found that astrocytes and microglia were activated in response to tau pathology and chronic cerebral hypoperfusion. Additionally, cerebral hypoperfusion increased a lysosomal enzyme, cathepsin D.

INTERPRETATION

These data together indicate that cerebral hypoperfusion reduces tau accumulation likely through an increase in microglial phagocytic activity towards tau and an elevation in degradation through cathepsin D. This study contributes to understanding the relationship between tau pathology and cerebrovascular diseases in older people with multimorbidity.

The Phenotype Changes of Astrocyte During Different Ischemia Conditions

OBJECTIVES

Dementia is becoming a major health problem in the world, and chronic brain ischemia is an established important risk factor in predisposing this disease. Astrocytes, as one major part of the blood-brain barrier (BBB), are activated during chronic cerebral blood flow hypoperfusion. Reactive astrocytes have been classified into phenotype pro-inflammatory type A1 or neuroprotective type A2. However, the specific subtype change of astrocyte and the mechanisms of chronic brain ischemia are still unknown.

METHODS

In order to depict the phenotype changes and their possible roles during this process, a rat bilateral common carotid artery occlusion model (BCAO) was employed in the present study. Meanwhile, the signaling pathways that possibly regulate these changes were investigated as well.

RESULTS

After four-week occlusion, astrocytes in the cortex of BCAO rats were shown to be the A2 phenotype, identified by the significant up-regulation of S100a10 accompanied by the down-regulation of Connexin 43 (CX43) protein. Next, we established in vitro hypoxia models, which were set up by stimulating primary astrocyte cultures from rat cortex with cobalt chloride, low glucose, or/and fibrinogen. Consistent with in vivo data, the cultured astrocytes also transformed into the A2 phenotype with the up-regulation of S100a10 and the down-regulation of CX43. In order to explore the mechanism of CX43 protein changes, C6 astrocyte cells were handled in both hypoxia and low-glucose stimulus, in which decreased pERK and pJNK expression were found.

CONCLUSIONS

In conclusion, our data suggest that in chronic cerebral ischemia conditions, the gradual ischemic insults could promote the transformation of astrocytes into A2 type instead of A1 type, and the phosphorylation of CX43 was negatively regulated by the phosphorylation of ERK and JNK. Also, our data could provide some new evidence of how to leverage the endogenous astrocytes phenotype changes during CNS injury by promoting them to be "protector" and not "culprit".

Downregulation of Notch Signaling-Stimulated Genes in Neurovascular Unit Alterations Induced by Chronic Cerebral Hypoperfusion

BACKGROUND

Chronic cerebral hypoperfusion (CCH) is a key contributor to vascular cognitive impairment (VCI) and is typically associated with blood-brain barrier (BBB) damage. This study investigates the pathological mechanisms underlying CCH-induced neurovascular unit (NVU) alterations.

METHODS

A mouse model of CCH was established using the bilateral common carotid artery stenosis (BCAS) procedure. Decreased cerebral blood flow (CBF) and impaired BBB integrity were assessed. Brain microvessel (BMV)-specific transcriptome profiles were analyzed using RNA-seq, supplemented with published single-cell RNA-seq data.

RESULTS

RNA-seq revealed neuroinflammation-related gene activation and significant downregulation of Notch signaling pathway genes in BMVs post-BCAS. Upregulated differentially expressed genes (DEGs) were enriched in microglia/macrophages, while downregulated DEGs were prominent in endothelial cells and pericytes. Enhanced activation of vascular-associated microglia (VAM) was linked to neurovascular alterations.

CONCLUSION

CCH induces significant NVU changes, marked by microglia-associated neuroinflammation and Notch signaling downregulation. These insights highlight potential therapeutic targets for treating neuroinflammatory and vascular-related neurodegenerative diseases.

Identification of toll-like receptor 2 as a key regulator of neuronal apoptosis in vascular dementia by bioinformatics analysis and experimental validation

BACKGROUND

Vascular dementia (VaD), the second most prevalent type of dementia, lacks a well-defined cause and effective treatment. Our objective was to utilize bioinformatics analysis to discover the fundamental disease-causing genes and pathological mechanisms in individuals diagnosed with VaD.

METHODS

To identify potential pathogenic genes associated with VaD, we conducted weighted gene co-expression network analysis (WGCNA), differential expression analysis, and protein-protein interaction (PPI) analysis. The exploration of potential biological mechanisms involved the utilization of Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis. Moreover, a bilateral common carotid artery stenosis (BCAS) mouse model of VaD was established, and the expression of the hub gene, its relationship with cognitive function and its potential pathogenic mechanism were verified by cognitive behavior tests, cerebral blood flow measurement, Western blotting, and immunofluorescence experiments.

RESULTS

This study identified 293 DEGs from the brain cortex of VaD patients and healthy controls, among these genes, the Toll-like receptor 2 (TLR2) gene was identified as hub gene, and it was associated with the apoptosis-related pathway PI3K/AKT.The BCAS model demonstrated that the use of TLR2 inhibitors greatly enhanced the cognitive function of the mice (p < 0.05). Additionally, there was a notable decrease in the number of apoptotic cells in the brain cortex of the mice (p < 0.01). Moreover, significant alterations in the levels of proteins related to the PI3K/AKT pathway and cleaved-caspase3 proteins were detected (p < 0.05).

CONCLUSIONS

TLR2 plays a role in the pathophysiology of VaD by enhancing the neuronal apoptotic pathway, suggesting it could be a promising therapeutic target.

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.

Bilateral Common Carotid Artery Stenosis in Mice: A Model of Chronic Cerebral Hypoperfusion-Induced Vascular Cognitive Impairment

Vascular cognitive impairment (VCI) is a syndrome defined as cognitive decline caused by vascular disease and is associated with various types of dementia. Chronic cerebral hypoperfusion (CCH) is one of the major contributors to VCI. Among the various rodent models used to study CCH-induced VCI, we have found the mouse bilateral common carotid artery stenosis (BCAS) model to be highly suitable. Here, we introduce the BCAS model of C57BL/6J mice generated using microcoils with an internal diameter of 0.18 mm. To produce the mouse BCAS model, the bilateral common carotid arteries are isolated from the adhering tissues and vagus nerves and twined around the microcoils. This model shows cognitive impairment and white matter lesions preceding neuronal dysfunction around postoperative day 28, which is similar to the human clinical picture. Overall, the mouse BCAS model will continue to be useful in studying CCH-induced VCI. Key features • This mouse BCAS model requires approximately 4 weeks to show phenotypes such as cognitive impairment and white matter injury.

From bench to bedside: US-Japan Collaborative Workshop on the NVU

The joint workshop between U.S. and Japanese researchers, supported by The U.S.-Japan Brain Research Cooperative Program, convened in January 2023 at Keio University Mita campus in Tokyo, Japan. The workshop had a threefold objective. Firstly, it aimed to facilitate robust exchanges between U.S. and Japanese researchers engaged in Neurovascular Unit (NVU) research, enhancing the global network of scholars in the field. Secondly, it aimed to encourage the initiation of collaborative research projects, fostering interdisciplinary efforts and synergistic advancements in understanding the brain vascular physiology and central nervous system. Lastly, the workshop emphasized the nurturing of young researchers, recognizing their pivotal role in shaping the future of NVU research. Throughout the workshop, participants discussed fundamental aspects of the NVU, exploring its complex connections and vital functions. By sharing their expertise and insights, the workshop attendees sought to uncover novel approaches to mitigate the burden of neurological diseases for individuals worldwide. This report provides a summary of the presentations and discussions held during the workshop, showcasing the collective efforts and progress made by the participants.

Chuanzhitongluo capsule improves cognitive impairment in mice with chronic cerebral hypoperfusion via the cholinergic anti-inflammatory pathway

Vascular cognitive impairment (VCI) has become a common disease-causing cognitive deficit in humans, second only to Alzheimer's Disease (AD). Chuanzhitongluo capsule (CZTL) is a Traditional Chinese Medicine (TCM) preparation known for its effective protection against cerebral ischemia. However, its potential to ameliorate VCI remains unclear. This study aimed to investigate the cognitive improvement effects of CZTL in a mouse model of VCI. Chronic cerebral hypoperfusion (CCH) was induced in mice by bilateral common carotid artery stenosis (BCAS) to simulate the pathological changes associated with VCI. Spatial learning and memory abilities were assessed using the Morris Water Maze (MWM). RNA sequencing (RNA-Seq) was employed to identify differentially expressed genes (DEGs) in the hippocampus. Levels of inflammatory factors were measured through enzyme-linked immunosorbent assay (ELISA), while immunofluorescence (IF) determined the expression intensity of target proteins. Western Blot (WB) confirmed the final action pathway. Results indicated that CZTL significantly improved the spatial learning and memory abilities of CCH mice, along with alterations in gene expression profiles in the hippocampus. It also reduced neuroinflammation in the hippocampus and upregulated the choline acetyltransferase (ChAT) and α7 subunit-containing nicotinic acetylcholine receptor (α7nAChR), which are in synaptic plasticity and neuronal development. Moreover, CZTL inhibited the NF-κB signaling pathway. In conclusion, CZTL may alleviate neuroinflammation induced by CCH and improve cognitive impairment in CCH mice by regulating the cholinergic anti-inflammatory pathway (CAIP) involving ChAT/α7nAChR/NF-κB.

Hope for vascular cognitive impairment: Ac-YVAD-cmk as a novel treatment against white matter rarefaction

Vascular cognitive impairment (VCI) is the second leading cause of dementia with limited treatment options, characterised by cerebral hypoperfusion-induced white matter rarefaction (WMR). Subcortical VCI is the most common form of VCI, but the underlying reasons for region susceptibility remain elusive. Recent studies employing the bilateral cortical artery stenosis (BCAS) method demonstrate that various inflammasomes regulate white matter injury and blood-brain barrier dysfunction but whether caspase-1 inhibition will be beneficial remains unclear. To address this, we performed BCAS on C57/BL6 mice to study the effects of Ac-YVAD-cmk, a caspase-1 inhibitor, on the subcortical and cortical regions. Cerebral blood flow (CBF), WMR, neuroinflammation and the expression of tight junction-related proteins associated with blood-brain barrier integrity were assessed 15 days post BCAS. We observed that Ac-YVAD-cmk restored CBF, attenuated BCAS-induced WMR and restored subcortical myelin expression. Within the subcortical region, BCAS activated the NLRP3/caspase-1/interleukin-1beta axis only within the subcortical region, which was attenuated by Ac-YVAD-cmk. Although we observed that BCAS induced significant increases in VCAM-1 expression in both brain regions that were attenuated with Ac-YVAD-cmk, only ZO-1 and occludin were observed to be significantly altered in the subcortical region. Here we show that caspase-1 may contribute to subcortical regional susceptibility in a mouse model of VCI. In addition, our results support further investigations into the potential of Ac-YVAD-cmk as a novel treatment strategy against subcortical VCI and other conditions exhibiting cerebral hypoperfusion-induced WMR.

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).

Recent advances in mechanistic, therapeutic, and diagnostic research of cerebrovascular diseases: updates from brain & BrainPET 2022

Cerebrovascular dysfunction and diseases are major causes of mortality, morbidity, and poor quality of patient life. Despite the enormous socioeconomic burden imposed by these conditions, therapeutic options remain scarce. However, rigorous preclinical and clinical research has augmented our mechanistic understanding of cerebrovascular diseases and underlying pathophysiological processes, and there is some optimism that novel therapeutic strategies may be developed in the next decade. This special collection comprises preclinical and clinical studies from investigators who presented their work at the Brain & BrainPET 2022 conference. It highlights recent research on cerebrovascular disease mechanisms, diagnosis, and treatments. A focus is set on cerebroprotective strategies during acute and chronic cerebral ischemia and predicting stroke risk and unfavorable outcomes. The special collection also sheds light on emerging novel treatment targets and management strategies in the pursuit of better clinical outcomes for patients with cerebrovascular diseases.

Differential reductions in the capillary red-blood-cell flux between retina and brain under chronic global hypoperfusion

Significance

It has been hypothesized that abnormal microcirculation in the retina might predict the risk of ischemic damages in the brain. Direct comparison between the retinal and the cerebral microcirculation using similar animal preparation and under similar experimental conditions would help test this hypothesis.

Aim

We investigated capillary red-blood-cell (RBC) flux changes under controlled conditions and bilateral-carotid-artery-stenosis (BCAS)-induced hypoperfusion, and then compared them with our previous measurements performed in the brain.

Approach

We measured capillary RBC flux in mouse retina with two-photon microscopy using a fluorescence-labeled RBC-passage approach. Key physiological parameters were monitored during experiments to ensure stable physiology.

Results

We found that under the controlled conditions, capillary RBC flux in the retina was much higher than in the brain (i.e., cerebral cortical gray matter and subcortical white matter), and that BCAS induced a much larger decrease in capillary RBC flux in the retina than in the brain.

Conclusions

We demonstrated a two-photon microscopy-based technique to efficiently measure capillary RBC flux in the retina. Since cerebral subcortical white matter often exhibits early pathological developments due to global hypoperfusion, our results suggest that retinal microcirculation may be utilized as an early marker of brain diseases involving global hypoperfusion.

Parameters of Auditory Evoked Related Potentials P300 in Disorders of Different Cognitive Function Domains (Visuospatial/Executive and Memory) in Elderly Hypertensive Persons

The neurophysiological correlates of certain types of cognitive impairment in relation to the spatial pattern of auditory cognitive evoked-related potentials (ERPs) in hypertensive persons remain unclear. The aim of this study was to determine the parameters of ERPs (N200, P300) in impaired different domains (visuospatial/executive and memory) of cognitive function in arterial hypertension, including cardiovascular ischemic events. A total of 46 patients (65-84 years) were observed. The clinical diagnosis of vascular dementia, the Montreal Cognitive Assessment Scale (MoCA test) and the spatial pattern of ERPs (N200, P300) were the parameters used to identify three groups: the Control Group without cognitive impairment (n = 13), the group with a leading memory disturbance (Memory Group, n = 20) and the group with a leading visuospatial/executive disturbance (VS/E Group, n = 13). In persons belonging to the Memory Group, N2 latency was prolonged in the central (C3 C4) and right parietal (P4) brain parts; latency of the motor component (P300) may remain similar to that of the ControlGroup. In persons belonging to theVS/E Group, maximal prolonged recognition time (N2), especially in the left central (C3), frontal-midline (Fz), right parietal (P3) and temporal (P4) brain parts, was observed; P300 latency in the central-midline (Cz) and left anterior-temporal (F7) brain parts among all the groups was revealed.