Constraint-Induced Movement Therapy Modulates Neuron Recruitment and Neurotransmission Homeostasis of the Contralesional Cortex to Enhance Function Recovery after Ischemic Stroke.

Stroke often results in long-term and severe limb dysfunction for a majority of patients, significantly limiting their activities and social participation. Constraint-induced movement therapy (CIMT) is a rehabilitation approach aimed explicitly at enhancing upper limb motor function following a stroke. However, the precise mechanism remains unknown. This study explores how CIMT may alleviate forelimb paralysis in ischemic mice, potentially through structural and functional remodeling of brain regions beyond the infarct area, especially the contralateral cortex. We demonstrated that CIMT recruits neurons from the contralesional cortex into the network that innervates the affected forelimb, as evidenced by PRV retrograde nerve tracing. Additionally, we investigated how CIMT influences synaptic plasticity in the contralateral cortex by evaluating synaptic growth marker levels and neurotransmission's homeostatic regulation. Our findings uncover a rehabilitative mechanism by which CIMT treats ischemic stroke, characterized by increased recruitment of neurons from the contralateral cortex into the network that innervates the affected forelimb, facilitated by homeostatic regulation of neurotransmission.

Constraint-induced movement therapy alleviates motor impairment by inhibiting the accumulation of neutrophil extracellular traps in ischemic cortex.

Stroke is a major cause of mortality and morbidity and most acute strokes are ischemic. Evidence-based medicine has demonstrated the effectiveness of constraint-induced movement therapy (CIMT) in the recovery of motor function in patients after ischemic stroke, but the specific treatment mechanism remains unclear. Herein, our integrated transcriptomics and multiple enrichment analysis studies, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis (GSEA) studies show that CIMT conduction broadly curtails immune response, neutrophil chemotaxis, and chemokine-mediated signaling pathway, CCR chemokine receptor binding. Those suggest the potential effect of CIMT on neutrophils in ischemic mice brain parenchyma. Recent studies have found that accumulating granulocytes release extracellular web-like structures composed of DNA and proteins called neutrophil extracellular traps (NETs), which destruct neurological function primarily by disrupting the blood-brain barrier and promoting thrombosis. However, the temporal and spatial distribution of neutrophils and their released NETs in parenchyma and their damaging effects on nerve cells remain unclear. Thus, utilizing immunofluorescence and flow cytometry, our analyses uncovered that NETs erode multiple regions such as primary motor cortex (M1), striatum (Str), nucleus of the vertical limb of the diagonal band (VDB), nucleus of the horizontal limb of the diagonal band (HDB) and medial septal nucleus (MS), and persist in the brain parenchyma for at least 14 days, while CIMT can reduce the content of NETs and chemokines CCL2 and CCL5 in M1. Intriguingly, CIMT failed to further reduce neurological deficits after inhibiting the NET formation by pharmacologic inhibition of peptidylarginine deiminase 4 (PAD4). Collectively, these results demonstrate that CIMT could alleviate cerebral ischemic injury induced locomotor deficits by modulating the activation of neutrophils. These data are expected to provide direct evidence for the expression of NETs in ischemic brain parenchyma and novel insights into the mechanisms of CIMT protecting against ischemic brain injury.

Corticostriatal Projections Relying on GABA Levels Mediate Exercise-Induced Functional Recovery in Cerebral Ischemic Mice.

Stroke is a neurological disorder characterized by high disability and death worldwide. The occlusion of the middle cerebral artery (MCAO) supplying the cortical motor regions and its projection pathway regions can either kill the cortical neurons or block their projections to the spinal cord and subcortical structure. The cerebral cortex is the primary striatal afferent, and the medium spiny neurons of the striatum have been identified as the major output neurons projecting to the substantia nigra and pallidum. Thus, disconnection of the corticostriatal circuit often occurs in the model of MCAO. In this study, we hypothesize that striatal network dysfunction in cerebral ischemic mice ultimately modulates the activity of striatal projections from cortical neurons to improve dysfunction during exercise training. In this study, we observed that the corticostriatal circuit originating from glutamatergic neurons could partially medicate the improvement of motor and anxiety-like behavior in mice with exercise. Furthermore, exercising or activating a single optogenetic corticostriatal circuit can increase the striatal gamma-aminobutyric acid (GABA) level. Using the GABA-A receptor antagonist, bicuculline, we further identified that the striatal glutamatergic projection from the cortical neurons relies on the GABAergic synapse's activity to modulate exercise-induced functional recovery. Overall, those results reveal that the dorsal striatum-projecting subpopulation of cortical glutamatergic neurons can influence GABA levels in the striatum, playing a critical role in modulating exercise-induced improvement of motor and anxiety-like behavior.

Repetitive Transcranial Magnetic Stimulation of the Brain After Ischemic Stroke: Mechanisms from Animal Models.

Stroke is a common cerebrovascular disease with high morbidity, mortality, and disability worldwide. Post-stroke dysfunction is related to the death of neurons and impairment of synaptic structure, which results from cerebral ischemic damage. Currently, transcranial magnetic stimulation (TMS) techniques are available to provide clinically effective interventions and quantitative diagnostic and prognostic biomarkers. The development of TMS has been 40 years and a range of repetitive TMS (rTMS) protocols are now available to regulate neuronal plasticity in many neurological disorders, such as stroke, Parkinson disease, psychiatric disorders, Alzheimer disease, and so on. Basic studies in an animal model with ischemic stroke are significant for demonstrating potential mechanisms of neural restoration induced by rTMS. In this review, the mechanisms were summarized, involving synaptic plasticity, neural cell death, neurogenesis, immune response, and blood-brain barrier (BBB) disruption in vitro and vivo experiments with ischemic stroke models. Those findings can contribute to the understanding of how rTMS modulated function recovery and the exploration of novel therapeutic targets. The mechanisms of rTMS in treating ischemic stroke from animal models. rTMS can prompt synaptic plasticity by increasing NMDAR, AMPAR and BDNF expression; rTMS can inhibit pro-inflammatory cytokines TNF and facilitate the expression of anti-inflammatory cytokines IL-10 by shifting astrocytic phenotypes from A1 to A2, and shifting microglial phenotypes from M1 to M2; rTMS facilitated the release of angiogenesis-related factors TGFß and VEGF in A2 astrocytes, which can contribute to vasculogenesis and angiogenesis; rTMS can suppress apoptosis by increasing Bcl-2 expression and inhibiting Bax, caspase-3 expression; rTMS can also suppress pyroptosis by decreasing caspase-1, IL-1ß, ASC, GSDMD and NLRP1 expression. rTMS, repetitive transcranial magnetic stimulation; NMDAR, N-methyl-D-aspartic acid receptors; AMPAR: α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors; BDNF, brain-derived neurotrophic factor; VEGF, vascular endothelial growth factor; GSDMD: cleaved Caspase-1 cleaves Gasdermin D; CBF: cerebral blood flow.

Regulation of microglia phagocytosis and potential involvement of exercise.

Microglia are considered the main phagocytic cells in the central nervous system, remodeling neural circuits by pruning synapses during development. Microglial phagocytosis is also a crucial process in maintaining adult brain homeostasis and clearing potential toxic factors, which are recognized to be associated with neurodegenerative and neuroinflammatory disorders. For example, microglia can engulf amyloid-ß plaques, myelin debris, apoptotic cells, and extracellular harmful substances by expressing a variety of specific receptors on the cell surface or by reprogramming intracellular glucose and lipid metabolism processes. Furthermore, physical exercise has been implicated to be one of the non-pharmaceutical treatments for various nervous system diseases, which is closely related to neuroplasticity and microglia functions including proliferation, activation, and phagocytosis. This review focuses on the central regulatory mechanisms related to microglia phagocytosis and the potential role of exercise training in this process.

Mirror therapy for unilateral neglect after stroke: A systematic review.

BACKGROUND AND PURPOSE: The effect of mirror therapy for unilateral neglect after stroke currently remains uncertain. METHODS: This systematic review investigated the effect of mirror therapy on neglect and daily living activities in patients with unilateral neglect after stroke when compared with no treatment, sham mirror therapy, or routinely applied therapies only. We performed a systematic electronic search of PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, and Wanfang Data to identify relevant randomized control trials (RCTs). RESULTS: We included five RCTs in the data synthesis. Mirror therapy (combined or not with other treatments) was more effective in improving neglect as compared with sham mirror therapy or no treatment (combined or not with the other therapies; standard mean difference [SMD] = 1.62, 95% confidence interval [CI] = 1.03-2.21, p < 0.00001). Mirror therapy (combined or not with other therapies) was effective in improving daily living activities as compared with sham mirror therapy or no treatment (combined or not with the other therapies; SMD = 2.09, 95% CI = 0.63-3.56, p = 0.005). CONCLUSIONS: Our results show that mirror therapy effectively improves neglect and daily living activities in patients with unilateral neglect after stroke. Future trials with high methodological quality and larger sample sizes are needed to determine the immediate and long-term effect of appropriate mirror therapy protocol for unilateral neglect.

Neutrophil Extracellular Traps Exacerbate Ischemic Brain Damage.

Most acute strokes are ischemic, and subsequent neuroinflammation promotes further damage leading to cell death but also plays a beneficial role by promoting cellular repair. Neutrophils are forerunners to brain lesions after ischemic stroke and exert elaborate functions. While neutrophil extracellular traps (NETs) possess a fundamental antimicrobial function within the innate immune system under physiological circumstances, increasing evidence indicates that NETosis, the release process of NETs, occurs in the pathogenic process of stroke. In this review, we focus on the processes of NET formation and clearance, the temporal and spatial alterations of neutrophils and NETs after ischemic damage, and how NETs are involved in several stroke-related phenomena. Generally, NET formation and release processes depend on the generation of reactive oxygen species (ROS) and the activation of nuclear peptidylarginine deiminase-4 (PAD4). The acid-base environment, oxygen concentration, and iron ions around the infarct may also impact NET formation. DNase 1 has been identified as the primary degrader of NETs in serum, while reactive microglia are expected to inhibit the formation of NETs around ischemic lesions by phagocytosis of neutrophils. The neutrophils and NETs are present in the perivascular space ipsilateral to the infarct arising after ischemic damage, peaking between 1 and 3 days postischemia, but their location in the brain parenchyma remains controversial. After the ischemic injury, NETs are involved in the destruction of neurological function primarily by disrupting the blood-brain barrier and promoting thrombosis. The potential effects of NETs on various ischemic nerve cells need to be further investigated, especially in the chronic ischemic phase.

SETD3 Downregulation Mediates PTEN Upregulation-Induced Ischemic Neuronal Death Through Suppression of Actin Polymerization and Mitochondrial Function.

SET domain protein 3 (SETD3) is an actin-specific methyltransferase, a rare post-translational modification with limited known biological functions. Till now, the function of SETD3 in cerebral ischemia-reperfusion (I/R)-induced injury remains unknown. Here, we show that the protein level of SETD3 is decreased in rat neurons after cerebral I/R injury. SETD3 promotes neuronal survival after both glucose and oxygen deprivation/reoxygenation (OGD/R) and cerebral I/R injury, and knockdown of SETD3 increases OGD/R-induced neuronal death. We further show that OGD/R-induced downregulation of SETD3 leads to the decrease of cellular ATP level, the reduction of mitochondrial electric potential and the increase of ROS production, thereby promoting mitochondrial dysfunction. We found that SETD3 reduction-induced mitochondrial dysfunction is mediated by the suppression of actin polymerization after OGD/R. Furthermore, we demonstrate that I/R-induced upregulation of PTEN leads to the downregulation of SETD3, and suppressing PTEN protects against ischemic neuronal death through downregulation of SETD3 and enhancement of actin polymerization. Together, this study provides the first evidence suggesting that I/R-induced downregulation of SETD3 mediates PTEN upregulation-induced ischemic neuronal death through downregulation of SETD3 and subsequent suppression of actin polymerization. Thus, upregulating SETD3 is a potential approach for the development of ischemic stroke therapy.

Identification of 2 Potential Core Genes for Influence of Gut Probiotics on Formation of Intracranial Aneurysms by Bioinformatics Analysis.

BACKGROUND Rupture of intracranial aneurysms (IA) is associated with high rates of mortality around the world. Use of intestinal probiotics can regulate the pathophysiology of aneurysms, but the details of the mechanism involved have been unclear. MATERIAL AND METHODS The GEO2R analysis website was used to detect the DEGs between IAs, AAAs, samples after supplementation with probiotics, and normal samples. The online tool DAVID provides functional classification and annotation analyses of associated genes, including GO and KEGG pathway. PPI of these DEGs was analyzed based on the STRING database, followed by analysis using Cytoscape software. RESULTS We found 170 intersecting DEGs (contained in GSE75240 and more than 2 of the 4 aneurysms datasets), 5 intersecting DEGs (contained in all datasets) and 1 intersecting DEG (contained in GSE75240 and all IAs datasets). GO analysis results suggested that the DEGs primarily participate in signal transduction, cell adhesion, immune response, response to drug, extracellular matrix organization, cell-cell signaling, and inflammatory response in the BP terms, and the KEGG pathways are mainly enriched in focal adhesion, cytokine-cytokine receptor interaction, ECM-receptor interaction, amoebiasis, chemokine signaling pathway, proteoglycans, and PI3K-Akt signaling pathway in cancer pathways. Through PPI network analysis, we confirmed 2 candidates for further study: CAV1 and MYH11. These downregulated DEGs are associated with the formation of aneurysms, and the change of these DEGs is the opposite in probiotics-treated animals. CONCLUSIONS Our study suggests that MYH11 and CAV1 are potential target genes for prevention of aneurysms. Further experiments are needed to verify these findings.

Effect of aerobic exercise on BDNF/proBDNF expression in the ischemic hippocampus and depression recovery of rats after stroke.

BDNF and proBDNF play an opposite role in hippocampal neurogenesis. What remains to be known is the effect of balance between BDNF and proBDNF in the ischemic hippocampus on pathogenesis of post-stroke depression (PSD) and the potential mechanisms of aerobic exercise (AE) on PSD. Wistar rats were randomly divided into control, Sham, Sedentary and AE groups. After PSD model was successful made, the blood lactate threshold corresponding speed (SLT) were measured. The behavioral tests (open field, forced swimming and sucrose preference tests) were performed before and after 4 weeks of aerobic treadmill training. HE staining and immunostaining for doublecortin (DCX)+ neurons were used to observe the changes of neuronal cell morphology and proliferation, migration of the neural progenitor cells (NPCs). The expression of mature brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B (TrkB), precursor BDNF (proBDNF), pan-neurotrophin receptor 75 (p75NTR) proteins, BDNF mRNA in the ischemic hippocampus and serum adrenocorticotropic hormone (ACTH) and corticosterone (CORT) were detected by Western blotting, immunohistochemistry, RT-PCR and ELISA. Higher immobility time and levels of proBDNF, p75NTR, ACTH, CORT proteins and lower sucrose preference, total distance, climbing frequency and levels of BDNF, TrkB proteins, BDNF mRNA were observed in the Sedentary group. Neuronal cells in the ischemic hippocampus were loosely arranged and expression of DCX reduced in the Sedentary group. There were significant differences in above results between Sedentary and AE groups after 4 weeks of aerobic exercise. The balance between BDNF and proBDNF in the ischemic hippocampus are likely to play an important role in the pathogenesis of PSD. And AE could improve depression, hippocampal neurogenesis, and increase BDNF/proBDNF ratio in the ischemic hippocampus of the PSD rats.

High-Intensity Interval Training on Neuroplasticity, Balance between Brain-Derived Neurotrophic Factor and Precursor Brain-Derived Neurotrophic Factor in Poststroke Depression Rats.

BACKGROUND: High-intensity interval training (HIIT) improves functional and mental health in the patients with stroke. To investigate the potential mechanisms of HIIT on poststroke depression (PSD). METHODS: Wistar rats were randomly divided into control, Sham, PSD, moderate intensity continuous training (MICT), and HIIT groups. After PSD model was successful made, the maximum speed (Smax) and the blood lactate threshold corresponding speed (SLT) were measured. Different intensity training protocols were performed on the MICT and HIIT groups, respectively. The behavioral tests (open field, forced swimming, and sucrose preference tests) were performed before and after training. Nissl staining was used to observe the changes of neuronal cell morphology in the left hippocampus. The expression of mature brain-derived neurotrophic factor (mBDNF), tropomyosin receptor kinase B (TrkB), precursor BDNF (proBDNF), pan-neurotrophin receptor 75 (p75NTR), NR2A, NR2B proteins, and BDNF, tissue plasminogen activator (tPA) mRNA in the hippocampus were detected by Western blotting, immunohistochemistry or RT-PCR after training. RESULTS: After 28 days of training, higher center occupancy, immobility time, and level of proBDNF, p75NTR, and NR2B proteins, lower sucrose preference and level of mBDNF, TrkB, NR2A proteins, and BDNF, tPA mRNA were observed in the PSD group. Neuronal cells and Nissl body in the hippocampus were loosely arranged and lightly stained in the PSD group. The ethological findings, Nissl staining especially in the CA1 and dentate gyrus areas, expression of proteins and mRNA above in the MICT and HIIT rats were reversed. And the HIIT group changed more significantly compared with MICT. CONCLUSIONS: HIIT was superior to MICT in improving depression in the PSD rats might via increasing mBDNF/proBDNF ratio and further improving neural plasticity in the hippocampus.