Apoptosis regulation in the penumbra after ischemic stroke: expression of pro- and antiapoptotic proteins

The advantages of multi-level omics research on stem cell-based therapies for ischemic stroke

Stem cell transplantation is a potential therapeutic strategy for ischemic stroke. However, despite many years of preclinical research, the application of stem cells is still limited to the clinical trial stage. Although stem cell therapy can be highly beneficial in promoting functional recovery, the precise mechanisms of action that are responsible for this effect have yet to be fully elucidated. Omics analysis provides us with a new perspective to investigate the physiological mechanisms and multiple functions of stem cells in ischemic stroke. Transcriptomic, proteomic, and metabolomic analyses have become important tools for discovering biomarkers and analyzing molecular changes under pathological conditions. Omics analysis could help us to identify new pathways mediated by stem cells for the treatment of ischemic stroke via stem cell therapy, thereby facilitating the translation of stem cell therapies into clinical use. In this review, we summarize the pathophysiology of ischemic stroke and discuss recent progress in the development of stem cell therapies for the treatment of ischemic stroke by applying multi-level omics. We also discuss changes in RNAs, proteins, and metabolites in the cerebral tissues and body fluids under stroke conditions and following stem cell treatment, and summarize the regulatory factors that play a key role in stem cell therapy. The exploration of stem cell therapy at the molecular level will facilitate the clinical application of stem cells and provide new treatment possibilities for the complete recovery of neurological function in patients with ischemic stroke.

A novel p55PIK signaling peptide inhibitor alleviates neuroinflammation via the STAT3/NF-kB signaling pathway in experimental stroke

BACKGROUND

Ischemic stroke remains the predominant contributor to mortality and disability globally. Microglia undergo rapid activation and initiate inflammatory cascade reactions by phenotypic polarization, participating in the regulation of inflammatory injury and tissue repair post-ischemic stroke. Regulating microglia-mediated neuroinflammation is a promising therapeutic strategy for ischemic stroke. Previously, we designed and synthesized a novel p55PIK inhibitor, TAT-N15 polypeptide, which presents inhibitive activity on NF-κB signaling-mediated inflammation in acute conjunctivitis and allergic rhinitis. The present study aimed to explore the therapeutic effect and mechanism of TAT-N15 on ischemia stroke.

METHODS

The mouse model of transient cerebral ischemia was made using the intraluminal filament method. After being treated with daily intraperitoneal injections of TAT-N15 (10 mg/kg) for 7 d, the neurological outcomes and the cerebral infarction volume were evaluated. Histopathology of the ischemia cerebral hemisphere was observed by H&E and Nissl staining. Neuronal survival, astrogliosis, and co-labeling of CD86/Iba1 and CD206/Iba1 were detected by immunofluorescence. The cell apoptosis was estimated by TUNEL staining. The expression levels of apoptosis-associated proteins, proinflammatory cytokines, protein markers of M1 and M2 microglia, and the phosphorylation of NF-κB and STAT3 proteins in the ischemic penumbra were detected by Western blot.

RESULTS

TAT-N15 treatment significantly decreased the infarct volume and alleviated neurological functional impairment, neuronal injury, and neuron apoptosis. Meanwhile, TAT-N15 treatment restrained the activation of microglia and astrocytes as well as the protein expression of proinflammatory cytokine in ischemic penumbra. Additionally, the administration of TAT-N15 treatment resulted in a significant reduction in the density of M1 phenotype microglia while concurrently increasing the density of M2 phenotype microglia within the ischemic penumbra. Finally, mechanical analysis unveiled that TAT-N15 exerted a substantial inhibitory effect on the protein expression of phosphorylated STAT3 and NF-κB.

CONCLUSION

TAT-N15 may inhibit neuroinflammation via regulating microglia activation and polarization through the STAT3/NF-κB pathway, which exhibits the neuroprotection effect in ischemic stroke.

The biological efficacy of Apelin against focal transient cerebral ischemia-reperfusion injury. A systematic review and meta-analysis of animal studies

BACKGROUND

Apelin has been extensively studied, and emerging experimental evidence suggests that Apelin may have effects on stroke by reducing infarct volume and neurological deficits, inhibiting the apoptosis process and reducing brain water content. However, the credibility of the evidence is uncertain. Thus, we aimed to perform a systematic review and meta-analysis to evaluate preclinical studies that used Apelin for the treatment of transient focal cerebral ischemia.

METHODS

Electronic bibliographic databases including PubMed, EMBASE, Scopus, and Google Scholar were searched for finding relevant studies from January 2000 to July 2023. The methodological quality and risk of bias scores for animal studies were calculated based on the CAMARADES and the SYRCLE's RoB tools, respectively. The effect sizes were assessed using Comprehensive Meta-Analysis (CMA) software.

RESULTS

A total of twelve eligible studies were used for the systematic review and meta-analysis. The median scores of study quality and risk of bias were 7.5 out of 10, and 5 out of 10, respectively. Apelin treatment effectively decreased infarct volume (primary outcome) [Hedges' g = 2.72, 95 % CI (1.93, 3.51), p < 0.001], neurological deficit [Hedges' g = 1.76, 95 % CI (0.96, 2.55), p < 0.001], cleaved caspase 3 [Hedges' g = 2.16, 95 % CI (0.87, 3.44), p = 0.001], and apoptotic cell number [Hedges' g = 4.07, 95 % CI (1.25,6.89), p = 0.005] compared with the control group. According to subgroup analysis, more notable neuroprotective effects were observed with intravenous administration than with intracerebroventricular (ICV) administration. Moreover, we determined that effect size of infarct volume was markedly related to the species. The combined measurement of two studies demonstrated that Apelin could reduce BCL2 and TNF-α levels as well as brain water content compared with the control group. However, pooled measurement of two studies showed that no relevancy was discovered between CHOP and altering infarct volume.

CONCLUSION

The present meta-analysis was conducted to assess preclinical studies related to Apelin treatment in rodent ischemic stroke. Apelin can exert promising neuroprotective effects by reducing infarct volume, neurological deficit, caspase 3, apoptotic cell number, TNF- α and brain water content and increasing BCL2. The current evidence supports the anti-apoptotic and anti-inflammatory properties of Apelin, but its effectiveness in decreasing CHOP level in animal models of ischemic stroke needs further elucidation. This study was registered within the International Prospective Register of Systematic Reviews (PROSPERO) as number CRD42023460926.

IL-17A exacerbates caspase-12-dependent neuronal apoptosis following ischemia through the Src-PLCγ-calpain pathway

Interleukin-17 A (IL-17 A) contributes to inflammation and causes secondary injury in post-stroke patients. However, little is known regarding the mechanisms that IL-17 A is implicated in the processes of neuronal death during ischemia. In this study, the mouse models of middle cerebral artery occlusion/reperfusion (MCAO/R)-induced ischemic stroke and oxygen-glucose deprivation/reoxygenation (OGD/R)-simulated in vitro ischemia in neurons were employed to explore the role of IL-17 A in promoting neuronal apoptosis. Mechanistically, endoplasmic reticulum stress (ERS)-induced neuronal apoptosis was accelerated by IL-17 A activation through the caspase-12-dependent pathway. Blocking calpain or phospholipase Cγ (PLCγ) inhibited IL-17 A-mediated neuronal apoptosis under ERS by inhibiting caspase-12 cleavage. Src and IL-17 A are linked, and PLCγ directly binds to activated Src. This binding causes intracellular Ca2+ flux and activates the calpain-caspase-12 cascade in neurons. The neurological scores showed that intracerebroventricular (ICV) injection of an IL-17 A neutralizing mAb decreased the severity of I/R-induced brain injury and suppressed apoptosis in MCAO mice. Our findings reveal that IL-17 A increases caspase-12-mediated neuronal apoptosis, and IL-17 A suppression may have therapeutic potential for ischemic stroke.

The alpha2-adrenergic receptor agonist clonidine protects against cerebral ischemia/reperfusion induced neuronal apoptosis in rats

Apoptosis is the crucial pathological mechanism following cerebral ischemic injury. Our previous studies demonstrated that clonidine, one agonist of alpha2-adrenergic receptor (α2-AR), could attenuate cerebral ischemic injury in a rat model of middle cerebral artery occlusion/reperfusion (MCAO/R). However, it's unclear whether clonidine exerts neuroprotective effects by regulating neuronal apoptosis. In this study, we elucidated whether clonidine can exert anti-apoptotic effects in cerebral ischemic injury, and further explored the possible mechanisms. Neurological deficit score was measured to evaluate the neurological function. TTC staining was used for the measurement of brain infarct size. Hematoxylin-Eosin (HE) staining was applied to examine the cell morphology. TUNEL and DAPI fluorescent staining methods were used to analyze the cell apoptosis in brain tissue. Fluorescence quantitative real-time PCR was performed to assess the gene expression of Caspase-3 and P53. Western blotting assay was applied to detect the protein expression of Caspase-3 and P53. The results showed that clonidine improved neurological function, reduced brain infarct size, alleviated neuronal damage, and reduced the ratio of cell apoptosis in the brain with MCAO/R injury. moreover, clonidine down-regulated the gene and protein expression of Caspase-3 and P53 which were over-expressed after MCAO/R injury. Whereas, yohimbine (one selective α2-AR antagonist) mitigated the anti-apoptosis effects of clonidine, accompanied by reversed gene and protein expression changes. The results indicated that clonidine attenuated cerebral MCAO/R injury via suppressing neuronal apoptosis, which may be mediated, at least in part, by activating α2-AR.

CaMKII activity and metabolic imbalance-related neurological diseases: Focus on vascular dysfunction, synaptic plasticity, amyloid beta accumulation, and lipid metabolism

Metabolic syndrome (MetS) is characterized by insulin resistance, hyperglycemia, excessive fat accumulation and dyslipidemia, and is known to be accompanied by neuropathological symptoms such as memory loss, anxiety, and depression. As the number of MetS patients is rapidly increasing globally, studies on the mechanisms of metabolic imbalance-related neuropathology are emerging as an important issue. Ca2+/calmodulin-dependent kinase II (CaMKII) is the main Ca2+ sensor and contributes to diverse intracellular signaling in peripheral organs and the central nervous system (CNS). CaMKII exerts diverse functions in cells, related to mechanisms such as RNA splicing, reactive oxygen species (ROS) generation, cytoskeleton, and protein-protein interactions. In the CNS, CaMKII regulates vascular function, neuronal circuits, neurotransmission, synaptic plasticity, amyloid beta toxicity, lipid metabolism, and mitochondrial function. Here, we review recent evidence for the role of CaMKII in neuropathologic issues associated with metabolic disorders.

Icariin inhibits apoptosis in OGD-induced neurons by regulating M2 pyruvate kinase

Background

Ischaemic stroke can lead to many complications, but treatment options are limited. Icariin is a traditional Chinese medicine with reported neuroprotective effects against ischaemic cerebral injury; however, the underlying mechanisms by which icariin ameliorates cell apoptosis require further study.

Purpose

This study aimed to investigate the therapeutic potential of icariin after ischaemic stroke and the underlying molecular mechanisms.

Methods

N2a neuronal cells were used to create an in vitro oxygen-glucose deprivation (OGD) model. The effects of icariin on OGD cells were assessed using the CCK-8 kit to detect the survival of cells and based on the concentration, apoptosis markers, inflammation markers, and M2 pyruvate kinase isoenzyme (PKM2) expression were detected using western blotting, RT-qPCR, and flow cytometry. To investigate the underlying molecular mechanisms, we used the PKM2 agonist TEPP-46 and detected apoptosis-related proteins.

Results

We demonstrated that icariin alleviated OGD-induced apoptosis in vitro. The expression levels of the apoptosis marker proteins caspase-3 and Bax were upregulated and Bcl-2 was downregulated. Furthermore, icariin reduced inflammation and downregulated the expression of PKM2. Moreover, activation of the PKM2 by pretreatment with the PKM2 agonist TEPP-46 enhanced the effects on OGD induced cell apoptosis in vitro.

Conclusion

This study elucidated the underlying mechanism of PKM2 in OGD-induced cell apoptosis and highlighted the potential of icariin in the treatment of ischaemic stroke.

The therapeutic role of SSEA3(+) human umbilical cord blood mononuclear cells in ischemic stroke model

Numerous evidences showed that human umbilical cord blood (UCB) mononuclear cells were a promising approach for the therapy of ischemic stroke(IS). The effect of stage-specific embryonic antigen 3 (SSEA3）positive subpopulation in UCB was not investigated in IS. In this study, we isolated SSEA3 positive cells from healthy UCB mononuclear cells, which comprised about 7.01% of the total UCB-mononuclear cells. Flow cytometry analysis revealed that SSEA3(+)UCB cells were almost positive for CD44 and CD45, and negative for CD73, CD90 and CD105. The expression of Oct3/4 in SSEA3(+)UCB cells were higher than that in UCB. SSEA3(+)UCB cells sorted by magnetic cell sorting were intravenously injected into the middle cerebral arterial occlusion(MCAO) rat model. Neurological score showed that SSEA3(+)UCB transplantation group exhibited significant improvements in the functional outcome of MCAO rats than UCB transplantation group. Nissl staining and microtubule association protein-2(MAP2) immunofluorescence staining showed that the SSEA3(+)UCB transplantation group decreased neuronal loss. SSEA3(+)UCB transplantation group reduced neuronal apoptosis, inhibited caspase3 expression, and decreased tumor necrosis factor α(TNF-α). These results indicate that SSEA3 positive cells are a novel subpopulation of UCB cells, which exhibit great potential for the treatment of ischemic stroke.

DAPK1 mediates cognitive dysfunction and neuronal apoptosis in PSD rats through the ERK/CREB/BDNF signaling pathway

Post-stroke depression (PSD) is one of the most common mental sequelae after a stroke and can damage the brain. Although PSD has garnered increasing attention in recent years, the precise mechanism remains unclear. Studies have indicated that the expression of DAPK1 is elevated in various neurodegenerative conditions, including depression, ischemic stroke, and Alzheimer's disease. However, the specific molecular mechanism of DAPK1-mediated cognitive dysfunction and neuronal apoptosis in PSD rats is unclear. In this study, we established a rat model of PSD, and then assessed depression-like behaviors and cognitive dysfunction in rats using behavioral tests. In addition, we detected neuronal apoptosis and analyzed the expression of DAPK1 protein and proteins related to the ERK/CREB/BDNF signaling pathway. The findings revealed that MCAO combined with CUMS can induce more severe depression-like behaviors and cognitive dysfunction in rats, while overexpression of DAPK1 may hinder the downstream ERK/CREB/BDNF signaling pathways, resulting in neuronal loss and exacerbation of brain tissue damage. In this study, we will focus on DAPK1 and explore its role in PSD.

Direct neuronal protection by the protease-activated receptor PAR4 antagonist ML354 after experimental stroke in mice

BACKGROUND AND PURPOSE

Thrombo-inflammation is a key feature of stroke pathophysiology and provides multiple candidate drug targets. Thrombin exerts coagulation-independent actions via protease-activated receptors (PAR), of which PAR1 has been implicated in stroke-associated neuroinflammation. The role of PAR4 in this context is less clear. This study examined if the selective PAR4 antagonist ML354 provides neuroprotection in experimental stroke and explored the underlying mechanisms.

EXPERIMENTAL APPROACH

Mouse primary cortical neurons were exposed to oxygen-glucose deprivation (OGD) and simulated reperfusion ± ML354. For comparison, functional Ca2+-imaging was performed upon acute stimulation with a PAR4 activating peptide or glutamate. Male mice underwent sham operation or transient middle cerebral artery occlusion (tMCAO), with ML354 or vehicle treatment beginning at recanalization. A subset of mice received a platelet-depleting antibody. Stroke size and functional outcomes were assessed. Abundance of target genes, proteins, and cell markers was determined in cultured cells and tissues by qPCR, immunoblotting, and immunofluorescence.

KEY RESULTS

Stroke up-regulated PAR4 expression in cortical neurons in vitro and in vivo. OGD augments spontaneous and PAR4-mediated neuronal activity; ML354 suppresses OGD-induced neuronal excitotoxicity and apoptosis. ML354 applied in vivo after tMCAO reduced infarct size, apoptotic markers, macrophage accumulation, and interleukin-1β expression. Platelet depletion did not affect infarct size in mice with tMCAO ± ML354.

CONCLUSIONS AND IMPLICATIONS

Selective PAR4 inhibition during reperfusion improves infarct size and neurological function after experimental stroke by blunting neuronal excitability, apoptosis, and local inflammation. PAR4 antagonists may provide additional neuroprotective benefits in patients with acute stroke beyond their canonical antiplatelet action.

Targeting lipid nanoparticles to the blood-brain barrier to ameliorate acute ischemic stroke

Effective delivery of mRNA or small molecule drugs to the brain is a significant challenge in developing treatment for acute ischemic stroke (AIS). To address the problem, we have developed targeted nanomedicine to increase drug concentrations in endothelial cells of the blood-brain barrier (BBB) of the injured brain. Inflammation during ischemic stroke causes continuous neuronal death and an increase in the infarct volume. To enable targeted delivery to the inflamed BBB, we conjugated lipid nanocarriers (NCs) with antibodies that bind cell adhesion molecules expressed at the BBB. In the transient middle cerebral artery occlusion mouse model, NCs targeted to vascular cellular adhesion molecule-1 (VCAM) achieved the highest level of brain delivery, nearly two orders of magnitude higher than untargeted ones. VCAM-targeted lipid nanoparticles with luciferase-encoding mRNA and Cre-recombinase showed selective expression in the ischemic brain. Anti-inflammatory drugs administered intravenously after ischemic stroke reduced cerebral infarct volume by 62% (interleukin-10 mRNA) or 35% (dexamethasone) only when they were encapsulated in VCAM-targeted NCs. Thus, VCAM-targeted lipid NCs represent a new platform for strongly concentrating drugs within the compromised BBB of penumbra, thereby ameliorating AIS.

Drugs/agents for the treatment of ischemic stroke: Advances and perspectives

Ischemic stroke (IS) poses a significant threat to global human health and life. In recent decades, we have witnessed unprecedented progresses against IS, including thrombolysis, thrombectomy, and a few medicines that can assist in reopening the blocked brain vessels or serve as standalone treatments for patients who are not eligible for thrombolysis/thrombectomy therapies. However, the narrow time windows of thrombolysis/thrombectomy, coupled with the risk of hemorrhagic transformation, as well as the lack of highly effective and safe medications, continue to present big challenges in the acute treatment and long-term recovery of IS. In the past 3 years, several excellent articles have reviewed pathophysiology of IS and therapeutic medicines for the treatment of IS based on the pathophysiology. Regretfully, there is no comprehensive overview to summarize all categories of anti-IS drugs/agents designed and synthesized based on molecular mechanisms of IS pathophysiology. From medicinal chemistry view of point, this article reviews a multitude of anti-IS drugs/agents, including small molecule compounds, natural products, peptides, and others, which have been developed based on the molecular mechanism of IS pathophysiology, such as excitotoxicity, oxidative/nitrosative stresses, cell death pathways, and neuroinflammation, and so forth. In addition, several emerging medicines and strategies, including nanomedicines, stem cell therapy and noncoding RNAs, which recently appeared for the treatment of IS, are shortly introduced. Finally, the perspectives on the associated challenges and future directions of anti-IS drugs/agents are briefly provided to move the field forward.

Implications of MMP-12 in the pathophysiology of ischaemic stroke

This article focuses on the emerging role of matrix metalloproteinase-12 (MMP-12) in ischaemic stroke (IS). MMP-12 expression in the brain increases dramatically in animal models of IS, and its suppression reduces brain damage and promotes neurological, sensorimotor and cognitive functional outcomes. Thus, MMP-12 could represent a potential target for the management of IS. This article provides an overview of MMP-12 upregulation in the brain following IS, its deleterious role in the post-stroke pathogenesis (blood-brain barrier disruption, inflammation, apoptosis and demyelination), possible molecular interactions and mechanistic insights, its involvement in post-ischaemic functional deficits and recovery as well as the limitations, perspectives, challenges and future directions for further research. Prior to testing any MMP-12-targeted therapy in patients with acute IS, additional research is needed to establish the effectiveness of MMP-12 suppression against IS in older animals and in animals with comorbidities. This article also examines the clinical implications of suppressing MMP-12 alone or in combination with MMP-9 for extending the currently limited tissue plasminogen activator therapy time window. Targeting of MMP-12 is expected to have a profound influence on the therapeutic management of IS in the future.

Neuroprotective Therapeutic Potential of microRNA-149-5p against Murine Ischemic Stroke

Ischemic stroke resulting from blockade of brain vessels lacks effective treatments, prompting exploration for potential therapies. Among promising candidates, microRNA-149 (miR-149) has been investigated for its role in alleviating oxidative stress, inflammation, and neurodegeneration associated with ischemic conditions. To evaluate its therapeutic effect, male Wistar rats were categorized into five groups, each consisting of 27 rats: sham, MCAO, lentiviral control, lentiviral miR-149, and miR149-5p mimic. Treatments were microinjected intracerebroventricularly (ICV) (right side), and ischemia was induced using middle cerebral artery occlusion (MCAO) procedure. Post-MCAO, neurological function, histopathological changes, blood-brain barrier (BBB) permeability, cerebral edema, and mRNA levels of Fas ligand (Faslg) and glutamate ionotropic NMDA receptor 1 (GRIN1) were assessed, alongside biochemical assays. MiR-149 administration improved neurological function, reduced brain damage, preserved BBB integrity, and attenuated cerebral edema. Upregulation of miR149-5p decreased Faslg and GRIN1 expression in ischemic brain regions. MiR-149 also reduced oxidative stress, enhanced antioxidant activity, decreased caspase-1 and - 3 activity, and modulated inflammatory factors in ischemic brain regions. Moreover, DNA fragmentation as an index of cell death decreased following miR-149 treatment. In conclusion, the study underscores miR-149 potential as a neuroprotective agent against ischemic stroke, showcasing its efficacy in modulating various mechanisms and supporting its candidacy as a promising therapeutic target for innovative strategies in stroke treatment.

Validation and application of caged Z-DEVD-aminoluciferin bioluminescence for assessment of apoptosis of wild type and TLR2-deficient mice after ischemic stroke

Programmed cell death or apoptosis is a critically important mechanism of tissue remodeling and regulates conditions such as cancer, neurodegeneration or stroke. The aim of this research article was to assess the caged Z-DEVD-aminoluciferin substrate for in vivo monitoring of apoptosis after ischemic stroke in TLR2-deficient mice and their TLR2-expressing counterparts. Postischemic inflammation is a significant contributor to ischemic injury development and apoptosis, and it is modified by the TLR2 receptor. Caged Z-DEVD-aminoluciferin is made available for bioluminescence enzymatic reaction by cleavage with activated caspase-3, and therefore it is assumed to be capable of reporting and measuring apoptosis. Apoptosis was investigated for 28 days after stroke in mice which ubiquitously expressed the firefly luciferase transgene. Middle cerebral artery occlusion was performed to achieve ischemic injury, which was followed with magnetic resonance imaging. The scope of apoptosis was determined by bioluminescence with caged Z-DEVD-aminoluciferin, immunofluorescence with activated caspase-3, flow cytometry with annexin-V and TUNEL assay. The linearity of Z-DEVD-aminoluciferin substrate dose effect was shown in the murine brain. Z-DEVD-aminoluciferin was validated as a good tool for monitoring apoptosis following adequate adjustment. By utilizing bioluminescence of Z-DEVD-aminoluciferin after ischemic stroke it was shown that TLR2-deficient mice had lower post-stroke apoptosis than TLR2-expressing wild type mice. In conclusion, Z-DEVD-aminoluciferin could be a valuable tool for apoptosis measurement in living mice.

Electroacupuncture regulates histone acetylation of Bcl-2 and Caspase-3 genes to improve ischemic stroke injury

Background

Imbalances between Bcl-2 and caspase-3 are significant evidence of apoptosis, which is considered an influential factor in rapidly occurring neuronal cell death and the decline of neurological function after stroke. Studies have shown that acupuncture can reduce poststroke brain cell damage via either an increase in Bcl-2 or a reduction in caspase-3 exposure. The current study aimed to investigate whether acupuncture could modulate Bcl-2 and caspase-3 expression through histone acetylation modifications, which could potentially serve as a neuroprotective mechanism.

Methods

This study used TTC staining, Nissl staining, Clark neurological system score, and Evans Blue (EB) extravasation to evaluate neurological damage following stroke. The expression of Bcl-2/caspase-3 mRNA was detected by real-time fluorescence quantification of PCR (real-time PCR), whereas the protein expression levels of Bcl-2, Bax, caspase-3, and cleaved caspase-3 were assessed using western blotting. TUNEL staining of the ischemic cortical neurons determined apoptosis in the ischemic cortex. Histone acetyltransferase (HAT) and histone deacetylase (HDAC) activities, along with the protein performance of AceH3, H3K9ace, and H3K27ace, were detected to evaluate the degree of histone acetylation. The acetylation enrichment levels of H3K9 and K3K27 in the Bcl-2/caspase-3 gene were assessed using Chromatin Immunoprecipitation (ChIP) assay.

Results

Our data demonstrated that electroacupuncture (EA) exerts a significant neuroprotective effect in middle cerebral artery occlusion (MCAO) rats, as evidenced by a reduction in infarct volume, neuronal damage, Blood-Brain Barrier (BBB) disruption, and decreased apoptosis of ischemic cortical neurons. EA treatment can promote the mRNA and protein expression of the Bcl-2 gene in the ischemic brain while reducing the mRNA and protein expression levels of caspase-3 and effectively decreasing the protein expression levels of Bax and cleaved caspase-3. More importantly, EA treatment enhanced the level of histone acetylation, including Ace-H3, H3K9ace, and H3K27ace, significantly enhanced the occupancy of H3K9ace/H3K27ace at the Bcl-2 promoter, and reduced the enrichment of H3K9ace and H3K27ace at the caspase-3 promoter. However, the Histone Acetyltransferase inhibitor (HATi) treatment reversed these effects.

Conclusions

Our data demonstrated that EA mediated the expression levels of Bcl-2 and caspase-3 in MCAO rats by regulating the occupancy of acetylated H3K9/H3K27 at the promoters of these two genes, thus exerting a cerebral protective effect in ischemic reperfusion (I/R) injury.

Molecular Mechanisms of Neuroprotection after the Intermittent Exposures of Hypercapnic Hypoxia

The review introduces the stages of formation and experimental confirmation of the hypothesis regarding the mutual potentiation of neuroprotective effects of hypoxia and hypercapnia during their combined influence (hypercapnic hypoxia). The main focus is on the mechanisms and signaling pathways involved in the formation of ischemic tolerance in the brain during intermittent hypercapnic hypoxia. Importantly, the combined effect of hypoxia and hypercapnia exerts a more pronounced neuroprotective effect compared to their separate application. Some signaling systems are associated with the predominance of the hypoxic stimulus (HIF-1α, A1 receptors), while others (NF-κB, antioxidant activity, inhibition of apoptosis, maintenance of selective blood-brain barrier permeability) are mainly modulated by hypercapnia. Most of the molecular and cellular mechanisms involved in the formation of brain tolerance to ischemia are due to the contribution of both excess carbon dioxide and oxygen deficiency (ATP-dependent potassium channels, chaperones, endoplasmic reticulum stress, mitochondrial metabolism reprogramming). Overall, experimental studies indicate the dominance of hypercapnia in the neuroprotective effect of its combined action with hypoxia. Recent clinical studies have demonstrated the effectiveness of hypercapnic-hypoxic training in the treatment of childhood cerebral palsy and diabetic polyneuropathy in children. Combining hypercapnic hypoxia with pharmacological modulators of neuro/cardio/cytoprotection signaling pathways is likely to be promising for translating experimental research into clinical medicine.

Naoxinqing tablet protects against cerebral ischemic/reperfusion injury by regulating ampkα/NAMPT/SIRT1/PGC-1α pathway

AIM OF THE STUDY

Naoxinqing (NXQ) tablets are derived from persimmon leaves and are widely used in China for promoting blood circulation and removing blood stasis in China. We aimed to explore whether NXQ has the therapeutic effect on ischemic stroke and explored its possible mechanism.

MATERIALS AND METHODS

The cerebral artery occlusion/reperfusion (MCAO/R) surgery was used to establish the cerebral ischemic/reperfusion rat model. NXQ (60 mg/kg and 120 mg/kg) were administered orally. The TTC staining, whole brain water content, histopathology staining, immunofluorescent staining, enzyme-linked immunosorbent assay (ELISA) and Western blot analyses were performed to determine the therapeutical effect of NXQ on MCAO/R rats.

RESULTS

The study demonstrated that NXQ reduced the cerebral infarction volumes and neurologic deficits in MCAO/R rats. The neuroprotective effects of NXQ were accompanied by inhibited oxidative stress and inflammation. The nerve regeneration effects of NXQ were related to regulating the AMPKα/NAMPT/SIRT1/PGC-1α pathway.

CONCLUSION

In summary, our results revealed that NXQ had a significant protective effect on cerebral ischemia-reperfusion injury in rats. This study broadens the therapeutic scope of NXQ tablets and provides new neuroprotective mechanisms of NXQ as an anti-stroke therapeutic agent.

A review of concepts and methods for FTIR imaging of biomarker changes in the post-stroke brain

Stroke represents a core area of study in neurosciences and public health due to its global contribution toward mortality and disability. The intricate pathophysiology of stroke, including ischemic and hemorrhagic events, involves the interruption in oxygen and nutrient delivery to the brain. Disruption of these crucial processes in the central nervous system leads to metabolic dysregulation and cell death. Fourier transform infrared (FTIR) spectroscopy can simultaneously measure total protein and lipid content along with a number of key biomarkers within brain tissue that cannot be observed using conventional techniques. FTIR imaging provides the opportunity to visualize this information in tissue which has not been chemically treated prior to analysis, thus retaining the spatial distribution and in situ chemical information. Here we present a review of FTIR imaging methods for investigating the biomarker responses in the post-stroke brain.

Treatment with β-sitosterol ameliorates the effects of cerebral ischemia/reperfusion injury by suppressing cholesterol overload, endoplasmic reticulum stress, and apoptosis

β-Sitosterol is a type of phytosterol that occurs naturally in plants. Previous studies have shown that it has anti-oxidant, anti-hyperlipidemic, anti-inflammatory, immunomodulatory, and anti-tumor effects, but it is unknown whether β-sitosterol treatment reduces the effects of ischemic stroke. Here we found that, in a mouse model of ischemic stroke induced by middle cerebral artery occlusion, β-sitosterol reduced the volume of cerebral infarction and brain edema, reduced neuronal apoptosis in brain tissue, and alleviated neurological dysfunction; moreover, β-sitosterol increased the activity of oxygen- and glucose-deprived cerebral cortex neurons and reduced apoptosis. Further investigation showed that the neuroprotective effects of β-sitosterol may be related to inhibition of endoplasmic reticulum stress caused by intracellular cholesterol accumulation after ischemic stroke. In addition, β-sitosterol showed high affinity for NPC1L1, a key transporter of cholesterol, and antagonized its activity. In conclusion, β-sitosterol may help treat ischemic stroke by inhibiting neuronal intracellular cholesterol overload/endoplasmic reticulum stress/apoptosis signaling pathways.

MRPS9-Mediated Regulation of the PI3K/Akt/mTOR Pathway Inhibits Neuron Apoptosis and Protects Ischemic Stroke

Neuronal apoptosis is crucial in the pathophysiology of ischemic stroke (IS), albeit its underly24ing mechanism remaining elusive. Investigating the mechanism of neuronal apoptosis in the context of IS holds substantial clinical value for enhancing the prognosis of IS patients. Notably, the MRPS9 gene plays a pivotal role in regulating mitochondrial function and maintaining structural integrity. Utilizing bioinformatic tactics and the extant gene expression data related to IS, we conducted differential analysis and weighted correlation network analysis (WGCNA) to select important modules. Subsequent gene interaction analysis via the STRING website facilitated the identification of the key gene-mitochondrial ribosomal protein S9 (MRPS9)-that affects the progression of IS. Moreover, possible downstream signaling pathways, namely PI3K/Akt/mTOR, were elucidated via Kyoto Encyclopedia of Gene and Genomes (KEGG) and Gene Ontology (GO) pathway analysis. Experimental models were established utilizing oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro and middle cerebral artery occlusion/reperfusion (MCAO/R) in mice. Changes in gene and protein expression, as well as cell proliferation and apoptosis, were monitored through qPCR, WB, CCK8, and flow cytometry. An OGD/R cell model was further employed to investigate the role of MRPS9 in IS post transfusion of MRPS9 overexpression plasmids into cells. Further studies were conducted by transfecting overexpressed cells with PI3K/Akt/mTOR signaling pathway inhibitor LY294002 to unveil the mechanism of MRPS9 in IS. Bioinformatic analysis revealed a significant underexpression of MRPS9 in ischemic stroke patients. Correspondingly, in vitro experiments with HN cells subjected to OGD/R treatment demonstrated a marked reduction in MRPS9 expression, accompanied by a decline in cell viability, and an increase cell apoptosis. Notably, the overexpression of MRPS9 mitigated the OGD/R-induced decrease in cell viability and augmentation of apoptosis. In animal models, MRPS9 expression was significantly lower in the MCAO/R group compared to the sham surgery group. Further, the KEGG pathway analysis associated MRPS9 expression with the PI3K/Akt/mTOR signaling pathway. In cells treated with the specific PI3K/Akt/mTOR inhibitor LY294002, phosphorylation levels of Akt and mTOR were decreased, cell viability decreased, and apoptosis increased compared to the MRPS9 overexpression group. These findings collectively indicate that MRPS9 overexpression inhibits PI3K/Akt/mTOR pathway activation, thereby protecting neurons from apoptosis and impeding IS progression. However, the PI3K/Akt/mTOR inhibitor LY294002 is capable of counteracting the protective effect of MRPS9 overexpression on neuronal apoptosis and IS. Our observations underscore the potential protective role of MRPS9 in modulating neuronal apoptosis and in attenuating the pathophysiological developments associated with IS. This is achieved through the regulation of the PI3K/Akt/mTOR pathway. These insights forge new perspectives and propose novel targets for the strategic diagnosis and treatment of IS.

Xingnaojing injection alleviates cerebral ischemia/reperfusion injury through regulating endoplasmic reticulum stress in Vivo and in Vitro

Background

Xingnaojing (XNJ) injection, an extract derived from traditional Chinese medicine, is commonly used to treat ischemic stroke (IS). Previous studies have shown that XNJ has the ability to alleviate apoptosis in cerebral ischemia-reperfusion injury. However, the potential mechanisms have not been clarified.

Objective

To identify the neuroprotective effect of XNJ and explore whether XNJ inhibits cell apoptosis associated with endoplasmic reticulum stress (ERS) after IS.

Methods

In this study, cultured hippocampal neurons from mouse embryos and Sprague-Dawley rats were assigned randomly to four groups: sham, model, XNJ, and edaravone. The treatment groups were administered 2 h after modelling. Neurological deficit scores and motor performance tests were performed after 24 h of modelling. Additionally, pathomorphology, cell apoptosis and calcium content were evaluated. To ascertain the expression of ERS proteins, western blotting and polymerase chain reaction were employed.

Results

The results indicated that XNJ treatment resulted in a notable decrease in infarct volume, apoptosis and missteps compared with the model group. XNJ also exhibited improvements in neurological function, grip strength and motor time. The calcium content significantly reduced in XNJ group. The XNJ administration resulted in a reduction in the levels of proteins associated with ERS including CHOP, GRP78, Bax, caspase-12, caspase-9, and cleaved-caspase-3, but an increase of the Bcl-2/Bax ratio. Furthermore, the downregulation of mRNA expression of CHOP, GRP78, caspase-12, caspase-9, and caspase-3 was confirmed in both cultured neurons and rat model.

Conclusion

These findings suggest that XNJ may alleviate apoptosis by modulating the ERS-induced apoptosis pathway, making it a potential novel therapeutic approach for ischemic stroke.

Synthesis, antioxidant and neuroprotective analysis of diversely functionalized α-aryl-N-alkyl nitrones as potential agents for ischemic stroke therapy

Herein, we report the synthesis, antioxidant and biological evaluation of 32 monosubstituted α-arylnitrones derived from α-phenyl-tert-butyl nitrone (PBN) in the search for neuroprotective compounds for ischemic stroke therapy, trying to elucidate the structural patterns responsible for their neuroprotective activity. Not surprisingly, the N-tert-butyl moiety plays beneficious role in comparison to other differently N-substituted nitrone groups. It seems that electron donor substituents at the ortho position and electron withdrawing substituents at the meta position of the aryl ring induce good neuroprotective activity. As a result, (Z)-N-tert-butyl-1-(2-hydroxyphenyl)methanimine oxide (21a) and (Z)-N-tert-butyl-1-(2-(prop-2-yn-1-yloxy)phenyl)methanimine oxide (24a) showed a significant increase in neuronal viability in an experimental ischemia model in primary neuronal cultures, and induced neuroprotection and improved neurodeficit score in an in vivo model of transient cerebral ischemia. These results showed that nitrones 21a and 24a are new effective small and readily available antioxidants, and suitable candidates for further structure optimization in the search for new phenyl-derived nitrones for the treatment of ischemic stroke and related diseases.

An Update of Kaempferol Protection against Brain Damage Induced by Ischemia-Reperfusion and by 3-Nitropropionic Acid

Kaempferol, a flavonoid present in many food products, has chemical and cellular antioxidant properties that are beneficial for protection against the oxidative stress caused by reactive oxygen and nitrogen species. Kaempferol administration to model experimental animals can provide extensive protection against brain damage of the striatum and proximal cortical areas induced by transient brain cerebral ischemic stroke and by 3-nitropropionic acid. This article is an updated review of the molecular and cellular mechanisms of protection by kaempferol administration against brain damage induced by these insults, integrated with an overview of the contributions of the work performed in our laboratories during the past years. Kaempferol administration at doses that prevent neurological dysfunctions inhibit the critical molecular events that underlie the initial and delayed brain damage induced by ischemic stroke and by 3-nitropropionic acid. It is highlighted that the protection afforded by kaempferol against the initial mitochondrial dysfunction can largely account for its protection against the reported delayed spreading of brain damage, which can develop from many hours to several days. This allows us to conclude that kaempferol administration can be beneficial not only in preventive treatments, but also in post-insult therapeutic treatments.

PCSK9 increases vulnerability of carotid plaque by promoting mitochondrial dysfunction and apoptosis of vascular smooth muscle cells

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has been recognized as a novel lipid-lowing target. Recent clinical studies suggested the value of inhibiting PCSK9 in decreasing the vulnerability of coronary plaques. However, the evidence of PCSK9-regulated evolution of unstable carotid plaques is unclear, which has limited the use of PCSK9 inhibitor in carotid plaques. This study aimed to determine the effect and molecular mechanisms of PCSK9 on vulnerability of carotid plaques, to provide potential therapeutic targets for stabilizing carotid plaques.

METHODS

The expression of PCSK9 in stable and unstable carotid plaques were examined in tissue and plasma. Human aortic vascular smooth muscle cells (VSMCs) and carotid VSMCs were employed to transfect lentivirus for overexpression and knockdown of PCSK9, respectively. Morphological and functional changes of mitochondria were observed by live-cell imaging. Cell apoptosis was evaluated by propidium iodide staining. RNA-sequencing and biological examinations were performed to explore and validate the underlying mechanisms. Truncated plasmids were employed to identify the functional domain of PCSK9 in regulation of VSMCs' mitochondrial morphology, function and apoptosis.

RESULTS

Clinically, PCSK9 was closely related with vulnerability of human carotid plaques. Increased expression of PCSK9 in human VSMCs was accompanied by higher level of apoptosis. At subcellular level of VSMCs, the morphology of mitochondria was shifted toward the fission state, followed by mitochondrial dysfunction. Inhibition of p38 MAPK activation partially rescued the above morphological and behavioral changes caused by PCSK9. Furthermore, inhibiting of dynamin-related protein 1 (DRP1) attenuated PCSK9-related mitochondrial dysfunction and cell apoptosis. The 1-149aa domain of PCSK9 protein was essential to achieve functional regulation to VSMCs.

CONCLUSION

Our findings demonstrated that PCSK9 induced morphology-related mitochondrial dysfunction and apoptosis of VSMCs, which may be related to increased vulnerability of carotid plaque.

Deterministic and stochastic approaches to a minimal model for the transition from autophagy to apoptosis

Autophagy and apoptosis are crucial cellular mechanisms. The cytoprotective function of autophagy is mediated by the negative regulation of apoptosis, which in turn inhibits autophagy. Although research into the molecular connection between autophagy and apoptosis is booming, the intricate regulatory mechanisms of this process are still not completely understood. Therefore, the objective of this study was to develop a minimal model to explore the transition from autophagy to apoptosis. This biological system was analyzed by comprehensively integrating both the deterministic and the stochastic dynamics of the cells. The system exhibited bistability, and the statistical properties of cells undergoing autophagy and apoptosis were analyzed at two different stress levels with varying noise strengths. Moreover, we investigated how noise affected the double negative feedback loops between autophagy and apoptosis and further triggered transitions at two different stress levels and initial conditions. Finally, the effect of noise on transition was comprehensively studied under continuous stress variations and the two different initial conditions, showing that stronger noise results in more randomness during the switching process. Our work may provide novel insights for further experiments and modeling.

Deciphering neuroprotective mechanism of nitroxoline in cerebral ischemia: network pharmacology and molecular modeling-based investigations

Cerebral ischemia is one of the major causes of death and disability worldwide. Currently, existing approved therapies are based on reperfusion and there is an unmet need to search for drugs with neuroprotective effects. The present study aims to investigate the neuroprotective mechanisms of nitroxoline, a nitro derivative of 8-Hydroxyquinoline, against cerebral ischemia using integrated network pharmacology and molecular docking approaches. Critical analytical tools used were SwissTarget, PharmMapper, BindingDB, DisGeNet, Cytoscape, GeneMANIA, ShinyGo, Metascape, GeneCodis, and Schrodinger GLIDE. Thirty-six overlapping drug and disease targets were identified and used for further analysis. Gene Ontology results showed that nitroxoline enriched the genes involved in biological processes of oxidative stress and apoptotic cell death that are highly implicated in hypoxic injury. KEGG enrichment analysis showed nitroxoline influenced a total of 159 biological pathways, out of which, top pathways involved in cerebral ischemia included longevity regulating pathway, VEGF signaling, EGFR tyrosine kinase inhibitor resistance, IL-17 and HIF-1 pathways, FoxO signaling, and AGE-RAGE pathway. Protein-protein interaction analysis using string database showed PARP1, EGFR, PTEN, BRD4, RAC1, NOS2, MTOR, MAPK3, BCL2, MAPK1, APP, METAP2, MAPK14, SIRT1, PRKAA1, and MCL1 as highly interactive proteins involved in pathogenesis of ischemic stroke regulated by nitroxoline. The highly interactive protein targets were validated by molecular docking studies and molecular dynamic simulations. Amongst all these targets, nitroxoline showed the highest binding affinity towards BRD4 followed by PARP1 and PTEN. Nitroxoline, through network pharmacology analysis, showed a role in regulating proteins, biological processes, and pathways crucial in cerebral ischemia. The current study thus provides a preliminary insight that nitroxoline might be used as a neuroprotectant against cerebral ischemia via modulating the epigenetic reader BRD4 and transcription factors such as RELA, NF-κβ1, and SP1. However, further in-vitro and preclinical studies need to be performed for concrete evidence.

Effects of isosakuranetin on cerebral infarction and blood brain barrier damage from cerebral ischemia/reperfusion injury in a rat model

This study investigated the effects of isosakuranetin (5,7-dihydroxy-4'-methoxyflavanone) on cerebral infarction and blood brain barrier (BBB) damage in cerebral ischemia and reperfusion (I/R) in a rat model. The right middle cerebral artery was occluded for 2 h followed by reperfusion. The experimental rats were divided into five groups: a sham, or control group; vehicle group; and 5 mg/kg, 10 mg/kg, and 20 mg/kg bodyweight isosakuranetin-treated I/R groups. After 24 h of reperfusion, the rats were tested using a six-point neurological function score. The percentage of cerebral infarction was evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) staining. BBB leakage was determined by Evan Blue injection assay and brain morphology changes were observed under light microscopy following staining with hematoxylin and eosin (H&E). The results of neurological function score revealed that isosakuranetin reduced the severity of neurological damage. A dose of 10 and 20 mg/kg bodyweight of isosakuranetin significantly decreased the infarct volume. All three doses of isosakuranetin significantly decreased Evan Blue leakage. The penumbra area of the I/R brains revealed the characteristics of apoptotic cell death. Therefore, isosakuranetin-treated I/R attenuated the brain damage from cerebral I/R injury and further investigation of the mechanisms warrant further investigation to assist in the development of protective strategies against cerebral I/R injury in clinical trials.Communicated by Ramaswamy H. Sarma.

Effect of salidroside on neuroprotection and psychiatric sequelae during the COVID-19 pandemic: A review

The coronavirus disease 2019 (COVID-19) pandemic has affected the mental health of individuals worldwide, and the risk of psychiatric sequelae and consequent mental disorders has increased among the general population, health care workers and patients with COVID-19. Achieving effective and widespread prevention of pandemic-related psychiatric sequelae to protect the mental health of the global population is a serious challenge. Salidroside, as a natural agent, has substantial pharmacological activity and health effects, exerts obvious neuroprotective effects, and may be effective in preventing and treating psychiatric sequelae and mental disorders resulting from stress stemming from the COVID-19 pandemic. Herein, we systematically summarise, analyse and discuss the therapeutic effects of salidroside in the prevention and treatment of psychiatric sequelae as well as its roles in preventing the progression of mental disorders, and fully clarify the potential of salidroside as a widely applicable agent for preventing mental disorders caused by stress; the mechanisms underlying the potential protective effects of salidroside are involved in the regulation of the oxidative stress, neuroinflammation, neural regeneration and cell apoptosis in the brain, the network homeostasis of neurotransmission, HPA axis and cholinergic system, and the improvement of synaptic plasticity. Notably, this review innovatively proposes that salidroside is a potential agent for treating stress-induced health issues during the COVID-19 pandemic and provides scientific evidence and a theoretical basis for the use of natural products to combat the current mental health crisis.

Rectangular method: a modified technique for sampling the ischemic border zone in a rat model of transient middle cerebral artery occlusion

To date, there have been three common methods for sampling the cerebral ischemic border zone in a rat model of transient middle cerebral artery occlusion (tMCAO): the "two o'clock method", the "diagonal method", and the "parallel line method". However, these methods have their own advantages and limitations. Here, we propose a modified technique (the "rectangular method") for sampling the ischemic border zone. A rat tMCAO model was prepared under the support of a compact small animal anesthesia machine. Cerebral blood flow was monitored by high-resolution laser Doppler to control the quality of modeling, and 2,3,5-triphenyl tetrazolium chloride (TTC) staining was used for cerebral infarction location assessment. Superoxide dismutase 2 (SOD2), cysteinyl aspartate specific proteinase (caspase)-3, caspase-9, and heat shock protein 70 (HSP70) were used to verify the reliability and reproducibility of the rectangular method. The expression of biomarkers (SOD2, caspase-3, caspase-9, and HSP70) in the traditional (two o'clock method after TTC staining) and modified (rectangular method) groups were increased. There were no significant differences between the groups. The rectangular method proposed herein is based on a modification of the diagonal method and parallel line method, which could provide a directly observable infarct borderline and a sufficient sampling area for subsequent experimental operations regardless of the cerebral infarct location. The assessed biomarkers (SOD2, caspase-3, caspase-9, and HSP70) demonstrated the reliability and reproducibility of the rectangular method, which may facilitate inter-laboratory comparisons.

Advances of phytotherapy in ischemic stroke targeting PI3K/Akt signaling

The pathogenesis of ischemic stroke is complex, and PI3K/Akt signaling is considered to play a crucial role in it. The PI3K/Akt pathway regulates inflammation, oxidative stress, apoptosis, autophagy, and vascular endothelial homeostasis after cerebral ischemia; therefore, drug research targeting the PI3K/Akt pathway has become the focus of scientists. In this review, we analyzed the research reports of antiischemic stroke drugs targeting the PI3K/Akt pathway in the past two decades. Because of the rich sources of natural products, increasing studies have explored the value of natural compounds, including Flavonoids, Quinones, Alkaloids, Phenylpropanoids, Phenols, Saponins, and Terpenoids, in alleviating neurological impairment and achieved satisfactory results. Herbal extracts and medicinal formulas have been applied in the treatment of ischemic stroke for thousands of years in East Asian countries. These precious clinical experiences provide a new avenue for research of antiischemic stroke drugs. Finally, we summarize and discuss the characteristics and shortcomings of the current research and put forward prospects for further in-depth exploration.

Knockout of Rnf213 Ameliorates Cerebral Ischemic-reperfusion Injury by Inhibiting Neuronal Apoptosis Through the Akt/GSK-3β/β-catenin/Bcl-2 Pathway

Previous studies by us and others have shown that RING finger protein 213 (RNF213) is associated with cerebrovascular disease and systemic vasculopathy. Indeed, Rnf213 mRNA expression is increased in cerebral ischemia reperfusion injury (CIRI). The purpose of the present study was to investigate the role of Rnf213 in CIRI. Using the middle cerebral artery occlusion (MCAO) model, we confirmed that the expression of RNF213 protein was significantly upregulated in neurons in the ischemic penumbra. Rnf213 knockout mice were successfully generated using CRISPR/Cas9 technology. According to TTC staining and Bederson neurological scale, removal of Rnf213 decreased brain infarct volume and improved neurological deficit score, although the restoration of cerebral blood flow after MCAO was similar in WT and Rnf213-/- mice. In addition, the levels of p-Akt, p-GSK-3β, β-catenin and Bcl-2 were significantly increased 24 h after MCAO in the ischemic penumbra of the Rnf213-/- mice compared to WT mice, indicating that Rnf213 removal may ameliorate neuronal apoptosis by regulating the Akt/GSK-3β/β-catenin/Bcl-2 signaling pathway. Taken together, our study reveals that Rnf213 regulates neuronal apoptosis in CIRI, therefore impacting on brain infarct volume in brain ischemia.

Involvement of histone methylation in the regulation of neuronal death

Neuronal death occurs in various physiological and pathological processes, and apoptosis, necrosis, and ferroptosis are three major forms of neuronal death. Neuronal apoptosis, necrosis, and ferroptosis are widely identified to involve the progress of stroke, Parkinson's disease, and Alzheimer's disease. A growing body of evidence has pointed out that neuronal death is tightly associated with expression of related genes and alteration of signaling molecules. In addition, recently, epigenetics has been increasingly focused on as a vital regulatory mechanism for neuronal apoptosis, necrosis, and ferroptosis, providing a new direction for treating nervous system diseases. Moreover, growing researches suggest that histone methylation or demethylation is involved in the processes of neuronal apoptosis, necrosis, and ferroptosis. These researches may imply that studying the potential roles of histone methylation is essential for treating the nervous system diseases. Here, we review potential roles of histone methylation and demethylation in neuronal death, which may give us a new direction in treating the nervous system diseases.

Low Glycolysis Is Neuroprotective during Anoxic Spreading Depolarization (SD) and Reoxygenation in Locusts

Migratory locusts enter a reversible hypometabolic coma to survive environmental anoxia, wherein the cessation of CNS activity is driven by spreading depolarization (SD). While glycolysis is recognized as a crucial anaerobic energy source contributing to animal anoxia tolerance, its influence on the anoxic SD trajectory and recovery outcomes remains poorly understood. We investigated the effects of varying glycolytic capacity on adult female locust anoxic SD parameters, using glucose or the glycolytic inhibitors 2-deoxy-d-glucose (2DG) or monosodium iodoacetate (MIA). Surprisingly, 2DG treatment shared similarities with glucose yet had opposite effects compared with MIA. Specifically, although SD onset was not affected, both glucose and 2DG expedited the recovery of CNS electrical activity during reoxygenation, whereas MIA delayed it. Additionally, glucose and MIA, but not 2DG, increased tissue damage and neural cell death following anoxia-reoxygenation. Notably, glucose-induced injuries were associated with heightened CO2 output during the early phase of reoxygenation. Conversely, 2DG resulted in a bimodal response, initially dampening CO2 output and gradually increasing it throughout the recovery period. Given the discrepancies between effects of 2DG and MIA, the current results require cautious interpretations. Nonetheless, our findings present evidence that glycolysis is not a critical metabolic component in either anoxic SD onset or recovery and that heightened glycolysis during reoxygenation may exacerbate CNS injuries. Furthermore, we suggest that locust anoxic recovery is not solely dependent on energy availability, and the regulation of metabolic flux during early reoxygenation may constitute a strategy to mitigate damage.

Crucial role of autophagy in propofol-treated neurological diseases: a comprehensive review

Neurological disorders are the leading cause of disability and death globally. Currently, there is a significant concern about the therapeutic strategies that can offer reliable and cost-effective treatment for neurological diseases. Propofol is a widely used general intravenous anesthetic in the clinic. Emerging studies demonstrate that propofol exerts neuroprotective effects on neurological diseases and disorders, while its underlying pathogenic mechanism is not well understood. Autophagy, an important process of cell turnover in eukaryotes, has been suggested to involve in the neuroprotective properties developed by propofol. In this narrative review, we summarized the current evidence on the roles of autophagy in propofol-associated neurological diseases. This study highlighted the effect of propofol on the nervous system and the crucial roles of autophagy. According to the 21 included studies, we found that propofol was a double-edged sword for neurological disorders. Several eligible studies reported that propofol caused neuronal cell damage by regulating autophagy, leading to cognitive dysfunction and other neurological diseases, especially high concentration and dose of propofol. However, some of them have shown that in the model of existing nervous system diseases (e.g., cerebral ischemia-reperfusion injury, electroconvulsive therapy injury, cobalt chloride-induced injury, TNF-α-induced injury, and sleep deprivation-induced injury), propofol might play a neuroprotective role by regulating autophagy, thus improving the degree of nerve damage. Autophagy plays a pivotal role in the neurological system by regulating oxidative stress, inflammatory response, calcium release, and other mechanisms, which may be associated with the interaction of a variety of related proteins and signal cascades. With extensive in-depth research in the future, the autophagic mechanism mediated by propofol will be fully understood, which may facilitate the feasibility of propofol in the prevention and treatment of neurological disorders.

Effects of adjuvant berberine therapy on acute ischemic stroke: A meta-analysis

We conducted a meta-analysis to evaluate the clinical efficacy of berberine (BBR) in treating acute ischemic stroke (AIS), explore its anti-inflammatory effects, and assess its potential applications for AIS patients. We comprehensively searched nine databases from inception until July 1, 2022, to identify clinical trials investigating the use of BBR in treating AIS. We performed statistical analyses using RevMan5.4 software and focused on primary outcomes such as inflammatory markers as well as secondary outcomes including immune system indicators, relevant biomarkers, carotid artery atherosclerosis, and adverse reactions. Our analysis included data from 17 clinical trials involving 1670 patients with AIS. Our results revealed that BBR in combination with conventional treatment significantly reduced levels of high-sensitivity C-reactive protein (hs-CRP), macrophage migration inhibitory factor (MIF), interleukin-6 (IL-6), complement C3, hypoxic inducible factor-1 α (HIF-1α), cysteine protease-3 (Caspase-3), the national institutes of health stroke scale (NIHSS), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), carotid intima-media thickness (IMT), the number of unstable plaques, and carotid crouse score on ultrasound when compared with conventional treatment alone. Furthermore, combining BBR with conventional treatment may improve the overall effective rate. Therefore, our findings suggest that BBR can be used as an adjuvant therapy for AIS due to its ability to reduce inflammatory cytokine levels, providing a novel therapeutic option for AIS. However, larger randomized controlled trials are necessary to confirm these results.

Neuroprotective Effects of Vinpocetine Against Ischemia-Reperfusion Injury Via Inhibiting NLRP3 Inflammasome Signaling Pathway

Ischemic stroke is one of the main causes of serious disability and death worldwide. NLRP3 inflammasome is an intracellular pattern recognition receptor composed of polyprotein complex, which participates in mediating a series of inflammatory responses and is considered as a potential target for the treatment of ischemic stroke. Vinpocetine, a derivative of vincamine, has been widely used in the prevention and treatment of ischemic stroke. However, the therapeutic mechanism of vinpocetine is not clear, and its effect on NLRP3 inflammasome remains to be determined. In this study, we used the mouse model of transient middle cerebral artery occlusion (tMCAO) to simulate the occurrence of ischemic stroke. Different doses of vinpocetine (5, 10, 15 mg/kg/d) were injected intraperitoneally for 3 days after ischemia-reperfusion in mice. The effects of different doses of vinpocetine on the degree of ischemia-reperfusion injury in mice were observed by TTC staining and modified neurological severity score scale, and the optimal dose was determined. Then, based on this optimal dose, we observed the effects of vinpocetine on apoptosis, microglial proliferation and NLRP3 inflammasome. In addition, we compared the effects of vinpocetine and MCC950 (a specific inhibitor of NLRP3 inflammasome) on NLRP3 inflammasome. Our results show that vinpocetine can effectively reduce the infarct volume and promote the recovery of behavioral function in stroke mice, and the maximal beneficial effects were observed at the dose of 10 mg/kg/d. Vinpocetine can effectively inhibit the apoptosis of peri-infarct neurons, promote the expression of Bcl-2, inhibit the expression of Bax and Cleaved Caspase-3, and reduce the proliferation of peri-infarct microglia. In addition, vinpocetine, like MCC950, can reduce the expression of NLRP3 inflammasome. Therefore, vinpocetine can effectively alleviate the ischemia-reperfusion injury in mice, and the inhibition of NLRP3 inflammasome may be an important therapeutic mechanism of vinpocetine.

Enhanced Cerebroprotection of Xenon-Loaded Liposomes in Combination with rtPA Thrombolysis for Embolic Ischemic Stroke

Xenon (Xe) has shown great potential as a stroke treatment due to its exceptional ability to protect brain tissue without inducing side effects. We have previously developed Xe-loaded liposomes for the ultrasound-activated delivery of Xe into the cerebral region and demonstrated their therapeutic efficacy. At present, the sole FDA-approved thrombolytic agent for stroke treatment is recombinant tissue plasminogen activator (rtPA). In this study, we aimed to investigate the potential of combining Xe-liposomes with an intravenous rtPA treatment in a clinically relevant embolic rat stroke model. We evaluated the combinational effect using an in vitro clot lysis model and an in vivo embolic middle cerebral artery occlusion (eMCAO) rat model. The treatment groups received intravenous administration of Xe-liposomes (20 mg/kg) at 2 h post-stroke onset, followed by the administration of rtPA (10 mg/kg) at either 2 or 4 h after the onset. Three days after the stroke, behavioral tests were conducted, and brain sections were collected for triphenyltetrazolium chloride (TTC) and TUNEL staining. Infarct size was determined as normalized infarct volume (%). Both in vitro and in vivo clot lysis experiments demonstrated that Xe-liposomes in combination with rtPA resulted in effective clot lysis comparable to the treatment with free rtPA alone. Animals treated with Xe-liposomes in combination with rtPA showed reduced TUNEL-positive cells and demonstrated improved neurological recovery. Importantly, Xe-liposomes in combination with late rtPA treatment reduced rtPA-induced hemorrhage, attributing to the reduction of MMP9 immunoreactivity. This study demonstrates that the combined therapy of Xe-liposomes and rtPA provides enhanced therapeutic efficacy, leading to decreased neuronal cell death and a potential to mitigate hemorrhagic side effects associated with late rtPA treatment.

Role of traditional Chinese medicine monomers in cerebral ischemia/reperfusion injury:a review of the mechanism

Ischemia/reperfusion (I/R) injury is a pathological process wherein reperfusion of an ischemic organ or tissue exacerbates the injury, posing a significant health threat and economic burden to patients and their families. I/R triggers a multitude of physiological and pathological events, such as inflammatory responses, oxidative stress, neuronal cell death, and disruption of the blood-brain barrier (BBB). Hence, the development of effective therapeutic strategies targeting the pathological processes resulting from I/R is crucial for the rehabilitation and long-term enhancement of the quality of life in patients with cerebral ischemia/reperfusion injury (CIRI). Traditional Chinese medicine (TCM) monomers refer to bioactive compounds extracted from Chinese herbal medicine, possessing anti-inflammatory and antioxidative effects, and the ability to modulate programmed cell death (PCD). TCM monomers have emerged as promising candidates for the treatment of CIRI and its subsequent complications. Preclinical studies have demonstrated that TCM monomers can enhance the recovery of neurological function following CIRI by mitigating oxidative stress, suppressing inflammatory responses, reducing neuronal cell death and functional impairment, as well as minimizing cerebral infarction volume. The neuroprotective effects of TCM monomers on CIRI have been extensively investigated, and a comprehensive understanding of their mechanisms can pave the way for novel approaches to I/R treatment. This review aims to update and summarize evidence of the protective effects of TCMs in CIRI, with a focus on their role in modulating oxidative stress, inflammation, PCD, glutamate excitotoxicity, Ca2+ overload, as well as promoting blood-brain barrier repairment and angiogenesis. The main objective is to underscore the significant contribution of TCM monomers in alleviating CIRI.

Acetylation of p53 in the Cerebral Cortex after Photothrombotic Stroke

p53 expression and acetylation are crucial for the survival and death of neurons in penumbra. At the same time, the outcome of ischemia for penumbra cells depends largely on the histone acetylation status, but the effect of histone acetyltransferases and deacetylases on non-histone proteins like p53 is largely understudied. With combined in silico and in vitro approach, we have identified enzymes capable of acetylation/deacetylation, distribution, stability, and pro-apoptotic activity of p53 in ischemic penumbra in the course of post-stroke recovery, and also detected involved loci of acetylation in p53. The dynamic regulation of the acetylation of p53 at lysine 320 is controlled by acetyltransferase PCAF and histone deacetylases HDAC1 and HDAC6. The in silico simulation have made it possible to suggest the acetylation of p53 at lysine 320 acetylation may facilitate the shuttling of p53 between the nucleus and cytoplasm in penumbra neurons. Acetylation of p53 at lysine 320 is more preferable than acetylation at lysine 373 and probably promotes survival and repair of penumbra neurons after stroke. Strategies to increase p53 acetylation at lysine 320 via increasing PCAF activity, inhibiting HDAC1 or HDAC6, inhibiting p53, or a combination of these interventions may have therapeutic benefits for stroke recovery and would be promising for neuroprotective therapy of stroke.

Mechanism of PGC-1α-mediated mitochondrial biogenesis in cerebral ischemia-reperfusion injury

Cerebral ischemia-reperfusion injury (CIRI) is a series of cascade reactions that occur after blood flow recanalization in the ischemic zone in patients with cerebral infarction, causing an imbalance in intracellular homeostasis through multiple pathologies such as increased oxygen free radicals, inflammatory response, calcium overload, and impaired energy metabolism, leading to mitochondrial dysfunction and ultimately apoptosis. Rescue of reversibly damaged neurons in the ischemic hemispheric zone is the key to saving brain infarction and reducing neurological deficits. Complex and active neurological functions are highly dependent on an adequate energy supply from mitochondria. Mitochondrial biogenesis (MB), a process that generates new functional mitochondria and restores normal mitochondrial function by replacing damaged mitochondria, is a major mechanism for maintaining intra-mitochondrial homeostasis and is involved in mitochondrial quality control to ameliorate mitochondrial dysfunction and thus protects against CIRI. The main regulator of MB is peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), which improves mitochondrial function to protect against CIRI by activating its downstream nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM) to promote mitochondrial genome replication and transcription. This paper provides a theoretical reference for the treatment of neurological impairment caused by CIRI by discussing the mechanisms of mitochondrial biogenesis during cerebral ischemia-reperfusion injury.

Targeting lipid nanoparticles to the blood brain barrier to ameliorate acute ischemic stroke

After more than 100 failed drug trials for acute ischemic stroke (AIS), one of the most commonly cited reasons for the failure has been that drugs achieve very low concentrations in the at-risk penumbra. To address this problem, here we employ nanotechnology to significantly enhance drug concentration in the penumbra's blood-brain barrier (BBB), whose increased permeability in AIS has long been hypothesized to kill neurons by exposing them to toxic plasma proteins. To devise drug-loaded nanocarriers targeted to the BBB, we conjugated them with antibodies that bind to various cell adhesion molecules on the BBB endothelium. In the transient middle cerebral artery occlusion (tMCAO) mouse model, nanocarriers targeted with VCAM antibodies achieved the highest level of brain delivery, nearly 2 orders of magnitude higher than untargeted ones. VCAM-targeted lipid nanoparticles loaded with either a small molecule drug (dexamethasone) or mRNA (encoding IL-10) reduced cerebral infarct volume by 35% or 73%, respectively, and both significantly lowered mortality rates. In contrast, the drugs delivered without the nanocarriers had no effect on AIS outcomes. Thus, VCAM-targeted lipid nanoparticles represent a new platform for strongly concentrating drugs within the compromised BBB of penumbra, thereby ameliorating AIS.

Graphical abstract

Acute ischemic stroke induces upregulation of VCAM. We specifically targeted upregulated VCAM in the injured region of the brain with drug- or mRNA-loaded targeted nanocarriers. Nanocarriers targeted with VCAM antibodies achieved the highest brain delivery, nearly orders of magnitude higher than untargeted ones. VCAM-targeted nanocarriers loaded with dexamethasone and mRNA encoding IL-10 reduced infarct volume by 35% and 73%, respectively, and improved survival rates.

Puerarin: a potential natural neuroprotective agent for neurological disorders

Puerarin is an isoflavone compound derived from Pueraria lobata in traditional Chinese medicine. Accumulating evidence has indicated that puerarin demonstrates multiple pharmacological effects and exhibits treatment potential for various neurological disorders. Based on the latest research progress on puerarin as a neuroprotective agent, its pharmacological activity, molecular mechanism, and therapeutic application were systematically reviewed with emphasis on pre-clinical studies. The related information was extracted and compiled from major scientific databases, including PubMed, ScienceDirect, SpringerLink, and Chinese National Knowledge Infrastructure, using 'Puerarin', 'Neuroprotection', 'Apoptosis', 'Autophagy', 'Antioxidant', 'Mitochondria', 'Anti-inflammation' as keywords. This review complied with The Preferred Reporting Items for Systematic Reviews criteria. Forty-three articles met established inclusion and exclusion criteria. Puerarin has shown neuroprotective effects against a variety of neurological disorders, including ischemic cerebrovascular disease, subarachnoid hemorrhage, epilepsy, cognitive disorders, traumatic brain injury, Parkinson's disease, Alzheimer's disease, anxiety, depression, diabetic neuropathy, and neuroblastoma/glioblastoma. Puerarin demonstrates anti-apoptosis, proinflammatory mediator inhibitory, autophagy regulatory, anti-oxidative stress, mitochondria protection, Ca²⁺ influx inhibitory, and anti-neurodegenerative activities. Puerarin exerts noticeable neuroprotective effects on various models of neurological disorders in vivo (animal). This review will contribute to the development of puerarin as a novel clinical drug candidate for the treatment of neurological disorders. However, well-designed, high-quality, large-scale, multicenter randomized clinical studies are needed to determine the safety and clinical utility of puerarin in patients with neurological disorders.

Protective effect and underlying mechanism of muscone on acute cerebral ischemia-reperfusion injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Musk is a widely used traditional Chinese medicine, which has resuscitation, activating blood, and disperse swelling effects. Musk is commonly used in the prevention of myocardial infarction and ischemic stroke, and muscone is its main active component.

AIM OF THE STUDY

The effect and mechanism of muscone to improve the condition of ischemic stroke is not clear, accordingly, we verified its efficacy in ischemia-reperfused rats, and investigated its mechanism by PC12 and THP-1 cells.

METHODS

A transient middle cerebral artery occlusion (tMCAO) rat model was established for in vivo experiments. 2,3,5-Triphenyl Tetrazolium Chloride (TTC) staining was used to calculate infarct rate. Neuroprotection and angiogenesis were assessed by Hematoxylin-eosin (HE) staining, nissl staining, immunofluorescence staining, and quantitative real-time PCR (qRT-PCR). Oxygen glucose deprivation-reperfusion (OGD/R) model of PC12 cells was established for neuroprotection analysis, where CCK-8 assay was used to measure cell viability, flow cytometry and Hoechst 33258 staining were used to demonstrate apoptosis, and protein levels were detected by Western blot. For angiogenesis analysis, enzyme-linked immunosorbent assay (ELISA) and qRT-PCR were used to detect angiogenic factors expressed by THP-1. Cell viability assay, scratch wound assay, and tube formation assay were used to evaluate angiogenic effect of HUVECs treated with medium of THP-1. And the angiogenic pathway in HUVECs was detected by Western blot.

RESULTS

According to the results, in cerebral ischemia-reperfusion rats, the infarct rate and tissue damage were significantly reduced by muscone, and the expression of neurotrophic factors and angiogenesis-related factors were all elevated. In OGD/R-PC12 cell models, muscone could increase cell viability and inhibit apoptosis via Bax/Bcl-2/Caspase-3 pathway. In THP-1-mediated angiogenesis of HUVECs, muscone promoted the secretion of angiogenesis-related factors in THP-1 and thus indirectly promoted the proliferation, migration and tube formation of HUVECs, and then regulated phosphorylation of VEGFR2 and Akt in HUVECs.

CONCLUSIONS

Our study indicated that muscone may be a potential neuroprotective and proangiogenic agent in cerebral ischemia.

Mechanism of action and therapeutic potential of dimethyl fumarate in ischemic stroke

Dimethyl fumarate (DMF) is an immunomodulatory drug currently approved for the treatment of multiple sclerosis and psoriasis. Its benefits on ischemic stroke outcomes have recently come to attention. To date, only tissue plasminogen activators (tPAs) and clot retrieval methods have been approved by the FDA for the treatment of ischemic stroke. Ischemic conditions lead to inflammation through diverse mechanisms, and recanalization can worsen the state. DMF and the nuclear factor erythroid-derived 2-related factor 2 (Nrf2) pathway it regulates seem to be important in postischemic inflammation, and animal studies have demonstrated that the drug improves overall stroke outcomes. Although the exact mechanism is still unknown, studies indicate that these beneficial impacts are due to the modulation of immune responses, blood-brain barrier permeability, and hemodynamic adjustments. One major component evaluated before, during, and after tPA therapy in stroke patients is blood pressure (BP). Recent studies have found that DMF may impact BP. Both hypotension and hypertension need correction before treatment, which may delay the appropriate intervention. Since BP management is crucial in managing stroke patients, it is important to consider DMF's role in this matter. That being said, it seems further investigations on DMF may lead to an alternative approach for stroke patients. In this article, we discuss the mechanistic roles of DMF and its potential role in stroke based on previously published literature and laboratory findings.

The role of protein glycosylation in the occurrence and outcome of acute ischemic stroke

Acute ischemic stroke (AIS) is a serious and life-threatening disease worldwide. Despite thrombolysis or endovascular thrombectomy, a sizeable fraction of patients with AIS have adverse clinical outcomes. In addition, existing secondary prevention strategies with antiplatelet and anticoagulant drugs therapy are not able to adequately decrease the risk of ischemic stroke recurrence. Thus, exploring novel mechanisms for doing so represents an urgent need for the prevention and treatment of AIS. Recent studies have discovered that protein glycosylation plays a critical role in the occurrence and outcome of AIS. As a common co- and post-translational modification, protein glycosylation participates in a wide variety of physiological and pathological processes by regulating the activity and function of proteins or enzymes. Protein glycosylation is involved in two causes of cerebral emboli in ischemic stroke: atherosclerosis and atrial fibrillation. Following ischemic stroke, the level of brain protein glycosylation becomes dynamically regulated, which significantly affects stroke outcome through influencing inflammatory response, excitotoxicity, neuronal apoptosis, and blood-brain barrier disruption. Drugs targeting glycosylation in the occurrence and progression of stroke may represent a novel therapeutic idea. In this review, we focus on possible perspectives about how glycosylation affects the occurrence and outcome of AIS. We then propose the potential of glycosylation as a therapeutic drug target and prognostic marker for AIS patients in the future.

Role of IL-17A in different stages of ischemic stroke

Interleukin-17A (IL-17A) plays an important role in the progression of ischemic stroke. IL-17A mediates the endothelial inflammatory response, promotes water and sodium retention, and changes the electrophysiological structure of the atrium, accelerating the progression of ischemic stroke risk factors such as atherosclerotic plaques, hypertension, and atrial fibrillation. In the acute phase of ischemic stroke, IL-17A mediates neuronal injury through neutrophil chemotaxis to the site of injury, the induction of neuronal apoptosis, and activation of the calpain-TRPC-6 (transient receptor potential channel-6) pathway. During ischemic stroke recovery, IL-17A, which is mainly derived from reactive astrocytes, promotes and maintains the survival of neural precursor cells (NPCs) in the subventricular zone (SVZ), neuronal differentiation, and synapse formation and participates in the repair of neurological function. Therapies targeting IL-17A-associated inflammatory signaling pathways can reduce the risk of ischemic stroke and neuronal damage and are a new therapeutic strategy for ischemic stroke and its risk factors. In this paper, we will briefly discuss the pathophysiological role of IL-17A in ischemic stroke risk factors, acute and chronic inflammatory responses, and the potential therapeutic value of targeting IL-17A.

A transient magnetic resonance spectroscopy peri-ischemic peak: a possible radiological biomarker of post-stroke neurogenesis

BACKGROUND AND AIMS

In adult human brain, neurogenesis seems to persist throughout life and ischemic stroke was proved to stimulate this process. Using magnetic resonance spectroscopy (MRS), a 1.28-ppm peak, putative biomarker of neural progenitor cells (NPCs), was identified both in vitro and in vivo, i.e., in normal rat and healthy human brain. The aim of our study was to identify a 1.28-ppm peak in adult human ischemic brain by using 3.0 T multivoxel MRS.

METHODS

We studied 10 patients, six males, and four females, with a mean (± SD) age of 59.3 (± 17.3), at three different time points from ischemic stroke onset (T0: < 5 days; T14: 14 ± 2 days; T30: 30 ± 2 days).

RESULTS

In all patients except one, a 1.28-ppm peak at T14 was detected at the ischemic boundary (all p values < 0.05). MRS performed on six voluntary age-matched healthy subjects did not detect any 1.28-ppm peak.

CONCLUSIONS

The nature of this 1.28-pm peak is uncertain; however, our data support the hypothesis that it might represent a marker of NPCs in post-stroke human brain.

Permissive hypercapnia and hypercapnic hypoxia inhibit signaling pathways of neuronal apoptosis in ischemic/hypoxic rats

INTRODUCTION

In the present study, we aimed to test the hypothesis that hypercapnia, independently and/or in combination with hypoxia, can activate signaling pathways related to the inhibition of proapoptotic (caspase-dependent and caspase-independent) factors and the induction of antiapoptotic factors in facilitating adaptation to hypoxia/ischemia.

MATERIALS AND METHODS

Following exposure to permissive hypercapnia and/or normobaric hypoxia, the degree of apoptosis was evaluated in experimental ischemia models in vivo and in vitro. The percentages of caspase-3, apoptosis-inducing factor (AIF), Bax, and Bcl-2 in astrocytes and neurons derived from male Wistar rats were also calculated. In vitro, cells were subjected to various types of respiratory exposure (hypoxia and/or hypercapnia for 24 or 12 h) as well as further sublethal chemical hypoxia. The percentages of these molecules in nerve cells in the ischemic penumbra of the brain after photothrombotic injury were also calculated.

RESULTS

The degree of apoptosis was found to decrease in ischemic penumbra, mostly due to the hypercapnic component. It was also discovered that the levels of caspase-3, AIF, and Bax decreased in this region, whereas the Bcl-2 levels increased following exposure to hypercapnia and hypercapnic hypoxia.

CONCLUSIONS

This integrative assessment of the rate of apoptosis/necrosis in astrocyte and neuron cultures shows that the combination of hypercapnia and hypoxia resulted in the maximum neuroprotective effect. The levels of apoptosis mediators in astrocyte and neuron cultures were calculated after modeling chemical hypoxia in vitro. These results show that the exposure models where permissive hypercapnia and normobaric hypoxia were combined also had the most pronounced inhibitory effects on apoptotic signaling pathways.