Rodent Models of Vascular Cognitive Impairment

Exploring the neuroprotective role of physical activity in cerebral small vessel disease

Cerebral small vessel disease (cSVD) is a common neurological finding characterized by abnormalities of the small blood vessels in the brain. Previous research has established a strong connection between cSVD and stroke, as well as neurodegenerative disorders, notably Alzheimer's disease (AD) and other dementias. As the search for effective interventions continues, physical activity (PA) has emerged as a potential preventative and therapeutic avenue. This review synthesizes the human and animal literature on the influence of PA on cSVD, highlighting the importance of determining optimal exercise protocols, considering aspects such as intensity, duration, timing, and exercise type. Furthermore, the necessity of widening the age bracket in research samples is discussed, ensuring a holistic understanding of the interventions across varying pathological stages of the disease. The review also suggests the potential of exploring diverse biomarkers and risk profiles associated with clinically significant outcomes. Moreover, we review findings demonstrating the beneficial effects of PA in various rodent models of cSVD, which have uncovered numerous mechanisms of neuroprotection, including increases in neuroplasticity and integrity of the vasculature and white matter; decreases in inflammation, oxidative stress, and mitochondrial dysfunction; and alterations in amyloid processing and neurotransmitter signaling. In conclusion, this review highlights the potential of physical activity as a preventive strategy for addressing cSVD, offering insights into the need for refining exercise parameters, diversifying research populations, and exploring novel biomarkers, while shedding light on the intricate mechanisms through which exercise confers neuroprotection in both humans and animal models.

Edaravone dexborneol attenuates cognitive impairment in a rat model of vascular dementia by inhibiting hippocampal oxidative stress and inflammatory responses and modulating the NMDA receptor signaling pathway

Exploring the intricate pathogenesis of Vascular Dementia (VD), there is a noted absence of potent treatments available in the current medical landscape. A new brain-protective medication developed in China, Edaravone dexboeol (EDB), has shown promise due to its antioxidant and anti-inflammatory properties, albeit with a need for additional research to elucidate its role and mechanisms in VD contexts. In a research setup, a VD model was established utilizing Sprague-Dawley (SD) rats, subjected to permanent bilateral typical carotid artery occlusion (2VO). Behavioral assessment of the rats was conducted using the Bederson test and pole climbing test, while cognitive abilities, particularly learning and memory, were evaluated via the novel object recognition test and the Morris water maze test. Ensuing, the levels of malondialdehyde (MDA), superoxide dismutase (SOD), IL-1β, IL-6, IL-4, and tumor necrosis factor-α (TNF-α) were determined through Enzyme-Linked Immunosorbent Assay (ELISA). Synaptic plasticity-related proteins, synaptophysin (SYP), post-synaptic density protein 95 (PSD-95), and N-methyl-D-aspartate (NMDA) receptor proteins (NR1, NR2A, NR2B) were investigated via Western blotting technique. The findings imply that EDB has the potential to ameliorate cognitive deficiencies, attributed to VD, by mitigating oxidative stress, dampening inflammatory responses, and modulating the NMDA receptor signaling pathway, furnishing new perspectives into EDB's mechanism and proposing potential avenues for therapeutic strategies in managing VD.

2-(4-Methylthiazol-5-yl) Ethyl Nitrate Hydrochloride Ameliorates Cognitive Impairment via Modulation of Oxidative Stress and Nuclear Factor Kappa B (NF-κB) Signaling Pathway in Chronic Cerebral Hypoperfusion-Associated Spontaneously Hypertensive Rats

Hypertension reduces the bioavailability of vascular nitric oxide (NO) and contributes to the onset of vascular dementia (VaD). A loss of NO bioavailability increases inflammation and oxidative stress. 2-(4-Methylthiazol-5-yl) ethyl nitrate hydrochloride (W1302) is a novel nitric oxide donor (NOD) which is undergoing phase I clinical trials in China for the treatment of VaD. In this study, we investigated the protective effects of W1302 in VaD rats induced by the permanent occlusion of a bilateral common carotid arteries model related to spontaneous hypertension (SHR-2VO), and we further explored the underlying mechanisms. Nimodipine was used as a positive control. Our results showed that W1302 treatment for 4 weeks (10 mg/Kg/day) exhibited stronger improvement in the spatial learning and memory deficits in SHR-2VO rats compared with nimodipine with slightly lower systolic blood pressure (SBP). Meanwhile, W1302 treatment significantly increased NO and cGMP production, restored mitochondrial membrane potential and attenuated oxidative stress as evidenced by increasing ATP production and reducing malondialdehyde (MDA) levels in the brain. Furthermore, W1302 treatment markedly inhibited the iNOS activity and decreased TNF-α expression via inhibiting the nuclear factor kappa B (NF-κB) signaling pathway. Nimodipine treatment also restored these aberrant changes, but its ATP production was weaker than that of W1302, and there was no significant effect on NO release. Taken together, W1302 exhibited beneficial effects on complications in VaD with hypertension, which is involved in suppressing oxidative damage, and the inflammatory reaction might be mediated by an increase in NO release. Therefore, W1302 has therapeutic potential for the treatment of VaD caused by chronic cerebral hypoperfusion-associated spontaneous hypertension.

Lipopolysaccharide-induced intestinal inflammation on AIM2-mediated pyroptosis in the brain of rats with cerebral small vessel disease

Cerebral small vessel disease (CSVD) is a cerebral vascular disease with insidious onset and poor clinical treatment effect, which is related to neuroinflammation. This study investigated whether lipopolysaccharide-induced intestinal inflammation enhanced the level of pyroptosis in the brain of rats with CSVD. The bilateral carotid artery occlusion (BCAO) model was selected as the object of study. Firstly, behavioral tests and Hematoxylin-eosin staining (HE staining) were performed to determine whether the model was successful, and then the AIM2 inflammasome and pyroptosis indexes (AIM2, ASC, Caspase-1, IL-1β, GSDMD, N-GSDMD) in the brain were detected by Western blotting and Immunohistochemistry (IHC). Finally, a single intraperitoneal injection of lipopolysaccharide (LPS) was used to induce intestinal inflammation in rats, the expression of GSDMD and N-GSDMD in the brain was analyzed by Western blotting and to see if pyroptosis caused by intestinal inflammation can be inhibited by Disulfiram, an inhibitor of pyroptosis. The results showed that the inflammatory response and pyroptosis mediated by the AIM2 inflammasome in BCAO rats were present in both brain and intestine. The expression of N-GSDMD, a key marker of pyroptosis, in the brain was significantly increased and inhibited by Disulfiram after LPS-induced enhancement of intestinal inflammation. This study shows that AIM2-mediated inflammasome activation and pyroptosis exist in both brain and intestine in the rat model of CSVD. The enhancement of intestinal inflammation will increase the level of pyroptosis in the brain. In the future, targeted regulation of the AIM2 inflammasome may become a new strategy for the clinical treatment of CSVD.

Effect of ferroptosis on chronic cerebral hypoperfusion in vascular dementia

Vascular dementia (VaD) is the second most prevalent type of dementia after Alzheimer's disease and is caused by impaired nerve cell function resulting from cerebrovascular disease and vascular risk factors. Chronic cerebral hypoperfusion (CCH) is a common pathological and physiological state that may result from cerebral ischemia and hypoxia, causing widespread diffuse lesions in the brain parenchyma which leads to progressive nerve damage. Transferrin (TF) and transferrin receptor 1 (TfR1), two proteins involved in iron uptake, were upregulated by CCH, whereas ferroprotein (FPN), a protein involved in iron efflux, was downregulated. This process may involve various mechanisms including tau and iron regulatory proteins (IRP). CCH can also exacerbate lipid peroxidation caused by an iron imbalance by inhibiting glutathione peroxidase 4 (Gpx4) synthesis and some Gpx4 independent pathways through cystine/glutamate transporters (system Xc-), ultimately leading to ferroptosis in nerve cells and accelerating the progression of VaD.

Transcriptome Profiling of Hippocampus After Cerebral Hypoperfusion in Mice

Chronic cerebral hypoperfusion (CCH) is considered to be one of the major mechanism in the pathogenesis of vascular cognitive impairment (VCI). Increased inflammatory cells, particularly microglia, often parallel hypoperfusion-induced gray matter damage such as hippocampal lesions, but the exact mechanism remains largely unknown. To understand the pathological mechanisms, we analyzed hippocampus-specific transcriptome profiles after cerebral hypoperfusion. The mouse hypoperfusion model was induced by employing the 0.16/0.18 mm bilateral common carotid artery stenosis (BCAS) procedure. Cerebral blood flow (CBF) was assessed after 3-week hypoperfusion. Pathological changes were evaluated via hematoxylin staining and immunofluorescence staining. RNA-sequencing (RNA-seq) was performed using RNA samples of sham- or BCAS-operated mice, followed by quantitative real-time PCR (qRT-PCR) validation. We found that the 0.16/0.18 mm BCAS induced decreased CBF, hippocampal neuronal loss, and microglial activation. Furthermore, GSEA between sham and BCAS mice showed activation of interferon-beta signaling along with inflammatory immune responses. In addition, integrative analysis with published single-cell RNA-seq revealed that up-regulated differentially expressed genes (DEGs) were enriched in a distinct cell type of "microglia," and down-regulated DEGs were enriched in "CA1 pyramidal," not in "interneurons" or "S1 pyramidal." This database of transcriptomic profiles of BCAS-hypoperfusion will be useful for future studies to explore potential targets for vascular cognitive dysfunction.

Research trends and hotspots of post-stroke cognitive impairment: a bibliometric analysis

Background: Post-stroke cognitive impairment (PSCI) is a major complication of stroke that affects more than one-third of stroke survivors, threatening their quality of life and increasing the risk of disability and death. Although various studies have described the etiology, epidemiology, and risk factors of PSCI, there are a limited number of comprehensive and accurate reports on research trends and hotspots in this field. Therefore, this review aimed to evaluate research trends, hotspots, and frontiers in PSCI using bibliometric analysis. Methods: We screened the literature spanning 20 years in the Web of Science Core Collection: Science Citation Index Expanded (SCI-Expanded) database from 1 January 2003 to 31 December 2022. We included all eligible literature reports based on our comprehensive search strategy, inclusion criteria, and exclusion criteria. The analysis of annual publications, countries/regions, institutions, journals, co-cited references, and keywords was conducted using CiteSpace and VOSviewer, and the hotspots and major findings of PSCI were summarized. Results: A total of 1,024 publications were included in this review. We found that the number of publications on PSCI increased annually. These publications were published in 75 countries or regions by over 400 institutions. Although Chinese institutions had the highest number of publications, their international influence was limited. The United States showed a strong influence in the field. The journal "Stroke" published the most publications (57) with a high impact factor and was considered the most co-cited journal. The most frequently cited references focused on the prevalence, incidence, neuropsychological assessment scales, criteria, and guidelines of PSCI. The strongest citation burst keywords for PSCI were "neurotrophic factor" and "synaptic plasticity", which were regarded as research focuses and research hotspots, respectively. Conclusion: This review provided a comprehensive summary of the literature of PSCI, identified the authoritative and frequently cited literature and journals, clarified the trends in PSCI research, and highlighted the hotspots in this field. Currently, studies on the mechanisms and treatment of PSCI are limited, and we hope that this review has effectively highlighted the research trajectory of PSCI and will lay the foundation for more innovative research in the future.

Neural Circuit Changes in Neurological Disorders: Evidence from in vivo Two-photon Imaging

Neural circuits, such as synaptic plasticity and neural activity, are critical components of healthy brain function. The consequent dynamic remodeling of neural circuits is an ongoing procedure affecting neuronal activities. Disruption of this essential process results in diseases. Advanced microscopic applications such as two-photon laser scanning microscopy have recently been applied to understand neural circuit changes during disease since it can visualize fine structural and functional cellular activation in living animals. In this review, we have summarized the latest work assessing the dynamic rewiring of postsynaptic dendritic spines and modulation of calcium transients in neurons of the intact living brain, focusing on their potential roles in neurological disorders (e.g. Alzheimer's disease, stroke, and epilepsy). Understanding the fine changes that occurred in the brain during disease is crucial for future clinical intervention developments.

Gastrodin and Gastrodigenin Improve Energy Metabolism Disorders and Mitochondrial Dysfunction to Antagonize Vascular Dementia

Vascular dementia (VD) is the second most common dementia syndrome worldwide, and effective treatments are lacking. Gastrodia elata Blume (GEB) has been used in traditional Chinese herbal medicine for centuries to treat cognitive impairment, ischemic stroke, epilepsy, and dizziness. Gastrodin (p-hydroxymethylphenyl-b-D-glucopyranoside, Gas) and Gastrodigenin (p-hydroxybenzyl alcohol, HBA) are the main bioactive components of GEB. This study explored the effects of Gas and HBA on cognitive dysfunction in VD and their possible molecular mechanisms. The VD model was established by bilateral common carotid artery ligation (2-vessel occlusion, 2-VO) combined with an intraperitoneal injection of sodium nitroprusside solution. One week after modeling, Gas (25 and 50 mg/kg, i.g.) and HBA (25 and 50 mg/kg, i.g.) were administered orally for four weeks, and the efficacy was evaluated. A Morris water maze test and passive avoidance test were used to observe their cognitive function, and H&E staining and Nissl staining were used to observe the neuronal morphological changes; the expressions of Aβ1-42 and p-tau396 were detected by immunohistochemistry, and the changes in energy metabolism in the brain tissue of VD rats were analyzed by targeted quantitative metabolomics. Finally, a Hippocampus XF analyzer measured mitochondrial respiration in H2O2-treated HT-22 cells. Our study showed that Gas and HBA attenuated learning memory dysfunction and neuronal damage and reduced the accumulation of Aβ1-42, P-Tau396, and P-Tau217 proteins in the brain tissue. Furthermore, Gas and HBA improved energy metabolism disorders in rats, involving metabolic pathways such as glycolysis, tricarboxylic acid cycle, and the pentose phosphate pathway, and reducing oxidative damage-induced cellular mitochondrial dysfunction. The above results indicated that Gas and HBA may exert neuroprotective effects on VD by regulating energy metabolism and mitochondrial function.

Recent advances in arterial spin labeling perfusion MRI in patients with vascular cognitive impairment

Cognitive impairment (CI) is a major health concern in aging populations. It impairs patients' independent life and may progress to dementia. Vascular cognitive impairment (VCI) encompasses all cerebrovascular pathologies that contribute to cognitive impairment (CI). Moreover, the majority of CI subtypes involve various aspects of vascular dysfunction. Recent research highlights the critical role of reduced cerebral blood flow (CBF) in the progress of VCI, and the detection of altered CBF may help to detect or even predict the onset of VCI. Arterial spin labeling (ASL) is a non-invasive, non-ionizing perfusion MRI technique for assessing CBF qualitatively and quantitatively. Recent methodological advances enabling improved signal-to-noise ratio (SNR) and data acquisition have led to an increase in the use of ASL to assess CBF in VCI patients. Combined with other imaging modalities and biomarkers, ASL has great potential for identifying early VCI and guiding prediction and prevention strategies. This review focuses on recent advances in ASL-based perfusion MRI for identifying patients at high risk of VCI.

What type of cell death occurs in chronic cerebral hypoperfusion? A review focusing on pyroptosis and its potential therapeutic implications

Chronic cerebral hypoperfusion (CCH) is a major global disease with chronic cerebral blood flow reduction. It is also the main cause of cognitive impairment and neurodegenerative diseases. Pyroptosis, a novel form of cell death, is characterized by the rupture of the cell membrane and the release of pro-inflammatory mediators. In recent years, an increasing number of studies have identified the involvement of pyroptosis and its mediated inflammatory response in the pathological process of CCH. Therefore, preventing the activation of pyroptosis following CCH is beneficial to inhibit the inflammatory cascade and reduce brain injury. In this review, we discuss the research progress on the relationship between pyroptosis and CCH, in order to provide a reference for research in related fields.

Vascular dementia: A microglia's perspective

Vascular dementia (VaD) is a second most common form of age-related dementia. It is characterized by cognitive impairment associated with vascular pathology, symptoms mainly caused by cerebral damage due to inadequate blood flow to the brain. The pathogenesis of VaD is complex, and a growing body of literature emphasizes on the involvement of microglia in disease development and progression. Here, we review the current knowledge on the role of microglia in regulating neuroinflammation under the pathogenesis of VaD. The commonly used animal and cell models for understanding the disease pathogenesis were summarized. The mechanisms by which microglia contribute to VaD are multifactorial, and we specifically focus on some of the predominant functions of microglia, including chemotaxis, secretory property, phagocytosis, and its crosstalk with other neurovascular unit cells. Finally, potential therapeutic strategies targeting microglia-modulated neuroinflammation are discussed.

Efficacy of acupuncture in animal models of vascular dementia: A systematic review and network meta-analysis

Background and purpose

Acupuncture is widely used in clinical practice for the treatment of vascular diseases. However, the protocol, efficacy, and mechanism of acupuncture in animal models of vascular dementia are still controversial. Based on the above problems, we initiated this comprehensive study.

Methods

To analyze the literatures included in this study, 4 databases were searched and the SYRCLE's Risk of bias tool was employed. To perform the subgroup analysis of different acupuncture methods and the Review Manager 5.3 was applied. Meanwhile, the pairwise and network meta-analysis were conducted using Addis 1.16.8. The outcomes included escape latency, number of crossings, time spent in the target quadrant, and swimming speed.

Results

Forty-two studies with a total of 1,486 animals were included in this meta-analysis. According to the results from subgroup analysis, GV20 + ST36 (Baihui + bilateral Zusanli) combined with 14-day manual acupuncture can obtain best improvement of the rats cognitive function among all acupuncture regimens (MD: -23.41; 95%CI: -26.66, -20.15; I2 = 0%; P < 0.001). The heterogeneity of other acupuncture treatments was significantly higher than that of GV20 + ST36, because the treatment courses were not uniform. Pair-wise and network comparisons are highly consistent. The major results of the network meta-analysis were as follows, In comparison to the impaired group, the acupuncture group showed significantly reduced escape latency (MD: -25.87; 95%CI: -30.75, -21.12), increased number of original platform crossings (MD: 2.63; 95%CI: 1.94, 3.34) and time spent in the target quadrant (MD: 7.88; 95%CI: 4.25, 11.44). The overall results of the network meta-analysis are as follows: the normal and sham-operated groups performed the best, followed by medicine and acupuncture, while no effect was found in the impaired group treated with non-acupoint and palliative.

Conclusions

Acupuncture significantly improves cognitive function in rats with vascular dementia. Compared to other acupuncture plans, (GV20 + ST36, MA) and 14 -day manual acupuncture can be used to obtain better results. The main mechanism of acupuncture in the treatment of vascular dementia is reduced oxidative stress, neuronal inflammation, and apoptosis, as well as the increased synaptic plasticity and neurotransmitters.

Systematic review registration

https://inplasy.com/inplasy-2021-11-0036/, identifier: INPLASY2021110036.

Deeper cerebral hypoperfusion leads to spatial cognitive impairment in mice

BACKGROUND

Vascular cognitive impairment (VCI) is the second-leading cause of dementia worldwide, which is caused by cerebrovascular diseases or relevant risk factors. However, there are no appropriate animal models, which can be used to study changes of neuropathology in the human VCI. To better understand the development of VCI, we modified three mouse models of chronical vascular diseases, and further compared the advantage and disadvantage of these models. We hope to establish a more suitable mouse model mimicking VCI in human beings.

METHODS

Adult male C57/BL6 mice (n=98) were used and animals underwent transient bilateral common carotid arteries occlusion (tBCCAO), or bilateral common carotid artery stenosis (BCAS), or right unilateral common carotid artery occlusion, respectively. Haemodynamic changes of surface cerebral blood flow (CBF) were examined up to 4 weeks. Spatial cognitive impairment was evaluated to determine the consequence of chronic cerebral ischaemia.

RESULTS

These mouse models showed different extents of CBF reduction and spatial reference memory impairment from 1 week up to 4 weeks postoperation compared with the control group (p<0.05). We found that (1) bilaterally ligation of common carotid artery caused decrease of 90% CBF in C57/BL6 mice (p<0.05) and caused acute instead of prolonged impairment of spatial reference memory (p<0.05); (2) unilateral ligation of common carotid artery did not cause severe ipsilateral ischaemia as seen in the tBCCAO mice and caused minor but significant spatial reference memory disturbance (p<0.05); and (3) 20% decrease in the bilateral CBF did not cause spatial reference memory impairment 4 weeks postoperation (p>0.05), while 30% decrease in bilateral or unilateral CBF led to significant memory disturbance in mice (p<0.05).

CONCLUSION

We demonstrated that BCAS using 0.16/0.18 mm microcoils is an alternative VCI mouse model when studying the mechanism and developing therapy of VCI.

Effect of Yisui Multipurpose Soup's Amelioration on D-Galactose-Induced Neuronal Cells

This study clarified the regulatory effect of Yisui multipurpose Soup towards D-galactose-induced cognitive impairment cell model on the molecular level. We first constructed and cultured the cell model of cognitive impairment induced by D-galactose in neurons in vitro and then cultured the cells in the medium supplemented with different doses of drug-containing serum of Yisui multipurpose soup. Expressions of inflammatory cytokine tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), nitric oxide (NO), and interleukin-1β (IL-1β) were assessed by the ELISA and western blot, and cell apoptosis was determined by flow cytometry and TUNEL. The expression changes of apoptosis-related proteins Bcl-2 and Bax were estimated by immunofluorescence, qPCR, and western blot. Finally, we analyzed and made the network interaction diagram of Yisui multipurpose soup-components-targets through the network pharmacology method, from which we could learn that there were 1104 gene targets related to vascular cognitive impairment (VCI) and 1071 component targets of Yisui multipurpose soup. And there were 251 overlapping genes, mainly gathering in protein binding, protein modification, MAPK signaling pathway, and calcium signaling pathway. The expressions of TNF-α, iNOS, NO, and IL-1β were significantly decreased after the culture medium was replaced by medium containing drug serum. We also found that the effect of high-dose drug-containing serum on the expression of inflammatory factors was better than that of low dose. The Yisui multipurpose soup drug serum in the medium not only significantly increased Bcl-2 expression and effectively reduced Bax expression, but also inhibited the apoptosis of neurons induced by D-galactose. In conclusion, Yisui multipurpose soup could effectively protect D-galactose-induced neuronal cell cognitive impairment by orchestrating expressions of the inflammatory factors TNF-α, iNOS, NO, and IL-1β and the apoptosis-related proteins Bcl-2 and Bax.

Gastrodin and Vascular Dementia: Advances and Current Perspectives

Gastrodia elata, a traditional Chinese medicine, has been widely used since ancient times to treat diseases such as dizziness, epilepsy, stroke, and memory loss. Gastrodin, one of the active components of Gastrodia elata, has been used in the treatment of migraine, epilepsy, Parkinson's disease, dementia, and depression in recent years. It can improve cognitive function and related neuropsychiatric symptoms through various effects and is considered as a promising treatment for dementia. Vascular dementia is a kind of severe cognitive impairment syndrome caused by vascular factors, and it is the dementia syndrome with the largest number of patients besides Alzheimer's disease. Although there is still a lack of evidence-based explorations, the paper reviewed the mechanism and methods of gastrodin in the treatment of vascular dementia, providing a reference for clinical therapy.

Electroacupuncture ameliorates neuroinflammation in animal models

Background:

Neuroinflammation refers to a wide range of immune responses occurring in the brain or spinal cord. It is closely related to a variety of neurodegenerative diseases, for which it potentially represents a new direction for treatment. Electroacupuncture (EA) is one method of acupuncture treatment, which can be used as an adjuvant therapy for many diseases. This review focuses on molecular mechanisms of EA in the reduction of neuroinflammation, summarizes relevant basic research and outlines future directions for investigation.

Findings:

A growing body of basic research has shown that EA can ameliorate neuroinflammation centrally (in animal models of ischemic stroke, Alzheimer’s disease, traumatic brain injury, spinal cord injury, Parkinson’s disease and vascular dementia) and peripherally (e.g. after a surgical insult or injection of lipopolysaccharide) and that its effects involve different molecular mechanisms, including activation of the α7 nicotinic acetylcholine receptor signaling pathway and P2 type purinergic receptors, inhibition of nuclear factor κB, and mitigation of damage secondary to oxidative stress and NOD-like receptor protein 3 inflammasome activation.

Conclusions:

EA is capable of regulating multiple cell signal transduction pathways to alleviate neuroinflammation in animal models. Although the findings of animal studies are encouraging, further prospective clinical trials are needed to verify the efficacy of EA for the treatment of neuroinflammation.

Thrombin induces ACSL4-dependent ferroptosis during cerebral ischemia/reperfusion

Ischemic stroke represents a significant danger to human beings, especially the elderly. Interventions are only available to remove the clot, and the mechanism of neuronal death during ischemic stroke is still in debate. Ferroptosis is increasingly appreciated as a mechanism of cell death after ischemia in various organs. Here we report that the serine protease, thrombin, instigates ferroptotic signaling by promoting arachidonic acid mobilization and subsequent esterification by the ferroptotic gene, acyl-CoA synthetase long-chain family member 4 (ACSL4). An unbiased multi-omics approach identified thrombin and ACSL4 genes/proteins, and their pro-ferroptotic phosphatidylethanolamine lipid products, as prominently altered upon the middle cerebral artery occlusion in rodents. Genetically or pharmacologically inhibiting multiple points in this pathway attenuated outcomes of models of ischemia in vitro and in vivo. Therefore, the thrombin-ACSL4 axis may be a key therapeutic target to ameliorate ferroptotic neuronal injury during ischemic stroke.

Inflammation and Rho-Associated Protein Kinase-Induced Brain Changes in Vascular Dementia

Patients with vascular dementia, caused by cerebral ischemia, experience long-term cognitive impairment due to the lack of effective treatment. The mechanisms of and treatments for vascular dementia have been investigated in various animal models; however, the insufficient information on gene expression changes that define pathological conditions hampers progress. To investigate the underlying mechanism of and facilitate treatment development for vascular dementia, we established a mouse model of chronic cerebral hypoperfusion, including bilateral carotid artery stenosis, by using microcoils, and elucidated the molecular pathway underlying vascular dementia development. Rho-associated protein kinase (ROCK) 1/2, which regulates cellular structure, and inflammatory cytokines (IL-1 and IL-6) were upregulated in the vascular dementia model. However, expression of claudin-5, which maintains the blood–brain barrier, and MAP2 as a nerve cell-specific factor, was decreased in the hippocampal region of the vascular dementia model. Thus, we revealed that ROCK pathway activation loosens the tight junction of the blood–brain barrier and increases the influx of inflammatory cytokines into the hippocampal region, leading to neuronal death and causing cognitive and emotional dysfunction. Our vascular dementia model allows effective study of the vascular dementia mechanism. Moreover, the ROCK pathway may be a target for vascular dementia treatment development in the future.

Comparison of Cognitive Performance and Cardiac Function Between Three Different Rat Models of Vascular Dementia

PURPOSE

Establishing an ideal animal model is essential for studying the pathogenesis, prevention and treatment of vascular dementia (VD). The present study was designed to compare the differences of behavior, cerebral blood flow (CBF), cardiac output and the levels of myocardial enzyme of three different VD rat models.

METHODS

The rats were randomly divided into sham-operated group (SHAM), permanent bilateral common carotid artery occlusion group (BCCAO), BCCAO combined with sodium nitroprusside (2.0mg·kg^-1) group (BCCAO+2.0SNP) and BCCAO combined with sodium nitroprusside (2.5mg·kg^-1) group (BCCAO+2.5SNP). After operation, Morris water maze test, echocardiographic evaluation and the measurement of CBF were performed, then the levels of myocardial enzymes in serum were assessed during euthanasia.

RESULTS

Compared with SHAM rats, the three VD model rats showed different degrees of cognitive impairment, lower cardiac output and CBF, and BCCAO rats showed higher levels of myocardial enzymes. Compared with BCCAO rats, the spatial learning ability of BCCAO+2.0SNP rats and BCCAO+2.5SNP rats was more severely impaired, while the levels of myocardial enzymes of BCCAO+2.0SNP rats were lower. Compared with BCCAO+2.0SNP rats, BCCAO+2.5SNP rats showed no significant difference in cognitive function and cardiac function.

CONCLUSION

Our present study demonstrated that all of the three different VD rat models exhibited cognitive and cardiac function impairment. The BCCAO+2.0SNP model and BCCAO+2.5SNP model damaged the spatial learning ability more seriously. The BCCAO+2.5SNP model caused more comprehensive cognitive impairment. In addition, the BCCAO+2.0SNP model and BCCAO+2.5SNP model might cause more serious damage to cardiac function.

Nuclear receptor coactivator 4-mediated ferritinophagy contributes to cerebral ischemia-induced ferroptosis in ischemic stroke

Ischemic stroke poses a significant health risk due to its high rate of disability and mortality. To address this problem, several therapeutic approaches have been proposed, including interruption targeting programmed cell death (PCD). Ferroptosis is a newly defined PCD characterized by iron-dependent accumulation of lipid peroxidation, and is becoming a promising target for treating numerous diseases. To explore the underlying mechanisms of the initiation and execution of ferroptosis in ischemic stroke, we established stroke models in vivo and in vitro simulating ischemia/reperfusion (I/R) neuronal injury. Different from previous reports on stroke, we tested ferroptosis by measuring the levels of core proteins, such as ACSL4, 15-LOX2, Ferritin and GPX4. In addition, I/R injury induces excessive degradation of ferritin via the autophagy pathway and subsequent increase of free iron in neurons. This phenomenon has recently been termed ferritinophagy and reported to be regulated by nuclear receptor coactivator 4 (NCOA4) in some cell lines. Increased NCOA4 in cytoplasm was detected in our study and then silenced by shRNA to investigate its function. Both in vivo and in vitro, NCOA4 deletion notably abrogated ferritinophagy caused by I/R injury and thus inhibited ferroptosis. Furthermore, we found that NCOA4 was upregulated by ubiquitin specific peptidase 14 (USP14) via a deubiquitination process in damaged neurons, and we found evidence of pharmacological inhibition of USP14 effectively reducing NCOA4 levels to protect neurons from ferritinophagy-mediated ferroptosis. These findings suggest a novel and effective target for treating ischemic stroke.

Cerebralcare Granule® combined with nimodipine improves cognitive impairment in bilateral carotid artery occlusion rats by reducing lipocalin-2

AIMS

Clinically, Cerebralcare Granule® (CG) has been widely utilized to treat various types of headache, chronic cerebral insufficiency and other diseases, and the effect is significant. Clinical studies have shown that CG can significantly relieve vascular dementia (VaD), however, the molecular mechanisms haven't been established. To clear the therapeutic mechanisms of CG against VaD, a hypothesis was proposed that CG could treat neurovascular injury by inhibiting the production of lipocalin-2 (LCN 2).

MAIN METHODS

90 dementia rats were selected by water maze test and randomly divided into 6 groups, including nimodipine (NM), CG L (low dose) (0.314 g kg^-1), CG H (high dose) (0.628 g kg^-1), and combined group (CG + NM). And in vitro neuronal cell OGD modeling to evaluate the effect of CG on JAK2/STAT3.

KEY FINDINGS

CG could significantly shorten the escape latency of two-vessel occlusion (2-VO) rats, increase their exploratory behavior, alleviate the symptoms of VaD and improve the ultrastructural pathological damage of neurovascular unit and accelerate the recovery of cerebral blood perfusion. CG combined with NM is better than NM alone. It was further showed that CG could inhibit the pathogenicity of LCN 2 through JAK2/STAT3 pathway and suppress the production of inflammatory cytokines. It plays a role in the protection of cerebral microvasculature and BBB in 2-VO rats.

SIGNIFICANCE

Taken together, there data has supported notion that CG can protect the integrity of cerebral blood vessels and BBB and improve cognitive impairment through mainly inhibiting LCN 2, which provides scientific evidence for clinical application.

Past, present and future role of retinal imaging in neurodegenerative disease

Retinal imaging technology is rapidly advancing and can provide ever-increasing amounts of information about the structure, function and molecular composition of retinal tissue in humans in vivo. Most importantly, this information can be obtained rapidly, non-invasively and in many cases using Food and Drug Administration-approved devices that are commercially available. Technologies such as optical coherence tomography have dramatically changed our understanding of retinal disease and in many cases have significantly improved their clinical management. Since the retina is an extension of the brain and shares a common embryological origin with the central nervous system, there has also been intense interest in leveraging the expanding armamentarium of retinal imaging technology to understand, diagnose and monitor neurological diseases. This is particularly appealing because of the high spatial resolution, relatively low-cost and wide availability of retinal imaging modalities such as fundus photography or OCT compared to brain imaging modalities such as magnetic resonance imaging or positron emission tomography. The purpose of this article is to review and synthesize current research about retinal imaging in neurodegenerative disease by providing examples from the literature and elaborating on limitations, challenges and future directions. We begin by providing a general background of the most relevant retinal imaging modalities to ensure that the reader has a foundation on which to understand the clinical studies that are subsequently discussed. We then review the application and results of retinal imaging methodologies to several prevalent neurodegenerative diseases where extensive work has been done including sporadic late onset Alzheimer's Disease, Parkinson's Disease and Huntington's Disease. We also discuss Autosomal Dominant Alzheimer's Disease and cerebrovascular small vessel disease, where the application of retinal imaging holds promise but data is currently scarce. Although cerebrovascular disease is not generally considered a neurodegenerative process, it is both a confounder and contributor to neurodegenerative disease processes that requires more attention. Finally, we discuss ongoing efforts to overcome the limitations in the field and unmet clinical and scientific needs.

Mechanisms of neuronal cell death in ischemic stroke and their therapeutic implications

Ischemic stroke caused by arterial occlusion is the most common type of stroke, which is among the most frequent causes of disability and death worldwide. Current treatment approaches involve achieving rapid reperfusion either pharmacologically or surgically, both of which are time-sensitive; moreover, blood flow recanalization often causes ischemia/reperfusion injury. However, even though neuroprotective intervention is urgently needed in the event of stroke, the exact mechanisms of neuronal death during ischemic stroke are still unclear, and consequently, the capacity for drug development has remained limited. Multiple cell death pathways are implicated in the pathogenesis of ischemic stroke. Here, we have reviewed these potential neuronal death pathways, including intrinsic and extrinsic apoptosis, necroptosis, autophagy, ferroptosis, parthanatos, phagoptosis, and pyroptosis. We have also reviewed the latest results of pharmacological studies on ischemic stroke and summarized emerging drug targets with a focus on clinical trials. These observations may help to further understand the pathological events in ischemic stroke and bridge the gap between basic and translational research to reveal novel neuroprotective interventions.

The Potential Role of Ferroptosis in Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent cause of dementia, accounting for approximately 60%-80%of all cases. Although much effort has been made over the years, the precise mechanism of AD has not been completely elucidated. Recently, great attention has shifted to the roles of iron metabolism, lipid peroxidation, and oxidative stress in AD pathogenesis. We also note that these pathological events are the vital regulators of a novel regulatory cell death, termed ferroptosis-an iron-dependent, oxidative, non-apoptotic cell death. Ferroptosis differs from apoptosis, necrosis, and autophagy with respect to morphology, biochemistry, and genetics. Mounting evidence suggests that ferroptosis may be involved in neurological disorders, including AD. Here, we review the underlying mechanisms of ferroptosis; discuss the potential interaction between AD and ferroptosis in terms of iron metabolism, lipid peroxidation, and the glutathione/glutathione peroxidase 4 axis; and describe some associated studies that have explored the implication of ferroptosis in AD.

FTY720 Prevents Spatial Memory Impairment in a Rat Model of Chronic Cerebral Hypoperfusion via a SIRT3-Independent Pathway

Vascular dementia (VD) and Alzheimer's disease (AD) are the most prevalent types of late-life dementia. Chronic cerebral hypoperfusion (CCH) contributes to both AD and VD. Recently, accumulating evidence has indicated that fingolimod (FTY720) is neuroprotective in acute cerebral ischemic stroke animal models, and the drug is now being used in clinical translation studies. However, fewer studies have addressed the role of FTY720 in chronic cerebral hypoperfusion (CCH)-related brain damage. In the present study, to investigate whether FTY720 can improve CCH-induced spatial memory loss and its underlying mechanism, two-vessel occlusion (2VO) rats were administered intraperitoneal FTY720 (1 mg/kg) for 7 consecutive weeks from post-operative day 8. Spatial memory was tested using the Morris Water Maze (MWM), and the rats' brains were harvested to allow molecular, biochemical, and pathological tests. We found that FTY720 treatment significantly reduced the escape latency and increased the target quadrant swimming time of the 2VO rats in the MWM task. The improvement in memory performance paralleled lower levels of pro-inflammatory cytokines and Iba-1 positive cells in the hippocampus of the 2VO rats, indicating that FTY720 had a beneficial effect in mitigating neuroinflammation. Furthermore, we found that FTY720 alleviated mitochondrial dysfunction in 2VO rats, as manifested by lower malondialdehyde levels, higher ATP content, and upregulation of ATP synthase activity in the hippocampus after treatment. FTY720 had no effect on the CCH-induced decrease in the activity of hippocampal Sirtuin-3, a master regulator of mitochondrial function and neuroinflammation. In summary, the results showed that FTY720 can improve CCH-induced spatial memory loss. The mechanism may involve Sirtuin-3-independent regulation of mitochondrial dysfunction and neuroinflammation in the hippocampus. The present study provides new clues to the pathological mechanism of CCH-induced cognitive impairment.