Subarachnoid Hemorrhage In Mice Research Articles

12/15-Lipooxygenase Inhibition Reduces Microvessel Constriction and Microthrombi after Subarachnoid Hemorrhage in Mice.

Impaired cerebral circulation, induced by blood vessel constrictions and microthrombi, leads to delayed cerebral ischemia after subarachnoid hemorrhage (SAH). 12/15-Lipooxygenase (12/15-LOX) overexpression has been implicated in worsening early brain injury outcomes following SAH. However, it is unknown if 12/15-LOX is important in delayed pathophysiological events after SAH. Since 12/15-LOX produces metabolites that induce inflammation and vasoconstriction, we hypothesized that 12/15-LOX leads to microvessel constriction and microthrombi formation after SAH, and thus 12/15-LOX is an important target to prevent delayed cerebral ischemia. SAH was induced in C57BL/6 and 12/15-LOX-/- mice of both sexes by endovascular perforation. Expression of 12/15-LOX was assessed in brain tissue slices and in vitro. C57BL/6 mice were administered either ML351 (12/15-LOX inhibitor) or vehicle. Mice were evaluated for daily neuroscore and euthanized on day five to assess cerebral 12/15-LOX expression, vessel constrictions, platelet activation, microthrombi, neurodegeneration, infarction, cortical perfusion, and for development of delayed deficits. Finally, the effect of 12/15-LOX inhibition on platelet activation was assessed in SAH patient samples using a platelet spreading assay. In SAH mice, 12/15-LOX was upregulated in brain vascular cells and there was an increase in 12-S-HETE. Inhibition of 12/15-LOX improved brain perfusion on days 4-5 and attenuated delayed pathophysiological events, including microvessel constrictions, microthrombi, neuronal degeneration, and infarction. Additionally, 12/15-LOX inhibition reduced platelet activation in human and mouse blood samples. Cerebrovascular 12/15-LOX overexpression plays a major role in brain dysfunction after SAH by triggering microvessel constrictions and microthrombi formation, which reduces brain perfusion. Inhibiting 12/15-LOX may be a therapeutic target to improve outcomes after SAH.

β-hydroxybutyrate alleviates neurological deficits by restoring glymphatic and inflammation after subarachnoid hemorrhage in mice

BackgroundBoth glymphatic system dysfunction and inflammatory response aggravate neurological dysfunction after subarachnoid hemorrhage (SAH). Studies have shown that β-hydroxybutyrate (BHB) may mitigate painful diabetic neuropathy (PDN) by upregulating SNTA1 expression and reinstating AQP4 polarity. However, the potential of BHB to ameliorate glymphatic system function and inflammatory response in SAH mice remains uncertain. MethodsThe SAH models were constructed by injection of arterial blood into cisterna Magana. Three groups of C57 mice were randomly assigned: Sham, SAH, and BHB. All mice were subjected to neurological function assessment, western blot, immunofluorescence double staining, and RNA-seq. Glymphatic system function was examined with tracer and immunofluorescence double staining, and the differential genes were examined with RNA-seq. In addition, the expression of related inflammation was detected. ResultsCompared with the SAH group, BHB reinstated AQP4 polarization by upregulating SNTA1 protein to enhance the glymphatic system. According to RNA-seq, the different genes were primarily connected to microglia activation, astrocytes, and inflammation. Western blot and immunofluorescence further confirmed that the related inflammatory protein expression levels were upregulated. BHB attenuated neuroinflammation after SAH. Ultimately, it can mitigate the neurological deficits in SAH mice. ConclusionThe study reveals a novel mechanism that BHB treatment mitigates neurologic impairment in SAH mice. We propose that BHB may play a neuroprotective effect by enhancing glymphatic system function and attenuating neuroinflammatory subarachnoid hemorrhage.

Validation of a Simplified Model for Subarachnoid Hemorrhage in Mice.

Subarachnoid hemorrhage (SAH) represents a severe injury to the brain and is associated with a high mortality (40%). Several experimental SAH models are described in the literature requiring specialized equipment and a high degree of surgical expertise. Our goal was to validate a simplified, cost-effective model to permit future studies of SAH. SAH was induced by injection of homologous blood into the cisterna magna. Perfusion-fixation then perfusion of gelatinous India ink was performed. Brains and brainstems were collected and imaged for analysis of cerebral vasospasm. Triphenyl tetrazolium chloride (TTC) staining was used to analyze brain tissue cell death 24 hours following stroke. A composite neuroscore was utilized to assess SAH-related neurologic deficits. Anterior cerebral artery and basilary artery diameters were significantly reduced at 24 hours post SAH induction. Middle cerebral artery diameter was also reduced; however, the results were not significant. TTC staining showed no infarcted tissue. Neuroscores were significantly lower in the SAH mice, indicating the presence of functional deficits. This simplified model of SAH elicits pathological changes consistent with those described for more complex models in the literature. Therefore, it can be used in future preclinical studies examining the pathophysiology of SAH and novel treatment options.

Low-dose IL-2 treatment confers anti-inflammatory effect against subarachnoid hemorrhage in mice

ObjectiveSubarachnoid hemorrhage (SAH) was a stroke with high occurrence and mortality. At the early stage, SAH patients have severe cerebral injury which is contributed by inflammation. In this study, we aimed to explore the anti-inflammation effect of low-dose IL-2 in SAH mice. MethodsThe 12-week-old C57BL/6J male mice were conducted with SAH surgery (Internal carotid artery puncture method). Different dose of IL-2 was injected intraperitoneally for 1 h, 1 day, and 2 days after SAH. Single-cell suspension and flow cytometry were used for the test of regulatory T (Treg) cells. Immunofluorescence staining was used to investigate the phenotypic polarization of microglia and inflammation response around neurons. Enzyme-Linked Immuno-sorbent Assay (ELISA) was applied to detect the level of pro-inflammatory factors. ResultsLow-dose IL-2 could enrich the Treg cells and drive the microglia polarizing to M2. The level of pro-inflammatory factors, IL-1α, IL-6, and TNF-α decreased in the low-dose IL-2 group. The inflammation response around neurons was attenuated. Low-dose IL-2 could increase the number of Treg cells, which could exert a neuroprotective effect against inflammation after SAH. ConclusionLow-dose IL-2 had the potential to be an effective clinical method to inhibit inflammation after SAH.

TIMP-3 Alleviates White Matter Injury After Subarachnoid Hemorrhage in Mice by Promoting Oligodendrocyte Precursor Cell Maturation

Subarachnoid hemorrhage (SAH) is associated with high mortality and disability rates, and secondary white matter injury is an important cause of poor prognosis. However, whether brain capillary pericytes can directly affect the differentiation and maturation of oligodendrocyte precursor cells (OPCs) and subsequently affect white matter injury repair has still been revealed. This study was designed to investigate the effect of tissue inhibitor of metalloproteinase-3 (TIMP-3) for OPC differentiation and maturation. PDGFRβret/ret and wild-type C57B6J male mice were used to construct a mouse model of SAH via endovascular perforation in this study. Mice were also treated with vehicle, TIMP-3 RNAi or TIMP-3 RNAi + TIMP-3 after SAH. The effect of TIMP-3 on the differentiation and maturation of OPCs was determined using behavioral score, ELISA, transmission electron microscopy, immunofluorescence staining and cell culture. We found that TIMP-3 was secreted mainly by pericytes and that SAH and TIMP-3 RNAi caused a significant decrease in the TIMP-3 content, reaching a nadir at 24 h, followed by gradual recovery. In vitro, the myelin basic protein content of oligodendrocytes after oxyhemoglobin treatment was increased by TIMP-3 overexpression. The data indicates TIMP-3 could promote the differentiation and maturation of OPCs and subsequently improve neurological outcomes after SAH. Therefore, TIMP-3 could be beneficial for repair after white matter injury and could be a potential therapeutic target in SAH.Graphical

P97 inhibits integrated stress response-induced neuronal apoptosis after subarachnoid hemorrhage in mice by enhancing proteasome function

Neuronal apoptosis is a common pathological change in early brain injury after subarachnoid hemorrhage (SAH), and it is closely associated with neurological deficits. According to previous research, p97 exhibits a remarkable anti-cardiomyocyte apoptosis effect. p97 is a critical molecule in the growth and development of the nervous system. However, it remains unknown whether p97 can exert an anti-neuronal apoptosis effect in SAH. In the present study, we examined the role of p97 in neuronal apoptosis induced after SAH and investigated the underlying mechanism. We established an in vivo SAH mice model and overexpressed the p97 protein through transfection of the mouse cerebral cortex. We analyzed the protective effect of p97 on neurons and evaluated short-term and long-term neurobehavior in mice after SAH. p97 was found to be significantly downregulated in the cerebral cortex of the affected side in mice after SAH. The site showing reduced p97 expression also exhibited a high level of neuronal apoptosis. Adeno-associated virus-mediated overexpression of p97 significantly reduced the extent of neuronal apoptosis, improved early and long-term neurological function, and repaired the neuronal damage in the long term. These neuroprotective effects were accompanied by enhanced proteasome function and inhibition of the integrated stress response (ISR) apoptotic pathway involving eIF2α/CHOP. The administration of the p97 inhibitor NMS-873 induced a contradictory effect. Subsequently, we observed that inhibiting the function of the proteasome with the proteasome inhibitor PS-341 blocked the anti-neuronal apoptosis effect of p97 and enhanced the activation of the ISR apoptotic pathway. However, the detrimental effects of NMS-873 and PS-341 in mice with SAH were mitigated by the administration of the ISR inhibitor ISRIB. These results suggest that p97 can promote neuronal survival and improve neurological function in mice after SAH. The anti-neuronal apoptosis effect of p97 is achieved by enhancing proteasome function and inhibiting the overactivation of the ISR apoptotic pathway.

Abstract 1236 Role of Platelets in the Development of Delayed Neurological Deficits after Subarachnoid Hemorrhage in Mice

Abstract 1236 Role of Platelets in the Development of Delayed Neurological Deficits after Subarachnoid Hemorrhage in Mice

Abstract WMP112: Neutrophil Extracellular Traps Occlude the Cerebrovasculature Causing Delayed Cerebral Ischemia After Subarachnoid Hemorrhage in Mice

Neutrophils are reported to be critical mediators of to poor outcome after subarachnoid hemorrhage (SAH). Following ischemic stroke, neutrophils cause vascular occlusion via neutrophil extracellular traps (NETs). In this study, our hypothesis was that NETs cause vascular occlusion leading to delayed cerebral ischemia (DCI) and worse outcome after SAH. SAH mice (male and female, young and aged) were administered one of the following: a neutrophil depleting antibody, a PAD4 inhibitor (to prevent NETosis), DNAse-I (to degrade NETs), or a vehicle (control). Mice had neurological assessment daily until day 7 and then were euthanized to quantify the amount of brain vascular NETs. Various subcohorts of mice were used to assess neutrophil propensity to NETose, in vivo formation of NETs via intravital microscopy, and MRI assessment of cerebral perfusion and infarct development. We also examined if NETs were present after SAH in 128 humans by measuring NETs markers via ELISA at 1, 2, 4, 7, and 10 days post-SAH. In mice, SAH induced a pro-NETosis phenotype selectively in skull neutrophils and caused intravascular NETs to be present by day 1 which persisted until at least day 7. Neutrophil depletion reduced NETs, improved cerebral perfusion and neurological outcome, and attenuated the incidence of DCI. Similar findings were observed for PAD4 inhibition. However, degrading NETs only marginally improved outcomes. Aneurysmal SAH patients who developed DCI had elevated markers of NETs compared to non-DCI patients. In conclusion, after SAH, skull-derived neutrophils are primed for NETosis, and neutrophils and NETosis are therapeutic targets to reduce DCI by preventing vascular occlusion by NETs.

Neutrophils and Neutrophil Extracellular Traps Cause Vascular Occlusion and Delayed Cerebral Ischemia After Subarachnoid Hemorrhage in Mice.

After subarachnoid hemorrhage (SAH), neutrophils are deleterious and contribute to poor outcomes. Neutrophils can produce neutrophil extracellular traps (NETs) after ischemic stroke. Our hypothesis was that, after SAH, neutrophils contribute to delayed cerebral ischemia (DCI) and worse outcomes via cerebrovascular occlusion by NETs. SAH was induced via endovascular perforation, and SAH mice were given either a neutrophil-depleting antibody, a PAD4 (peptidylarginine deiminase 4) inhibitor (to prevent NETosis), DNAse-I (to degrade NETs), or a vehicle control. Mice underwent daily neurological assessment until day 7 and then euthanized for quantification of intravascular brain NETs (iNETs). Subsets of mice were used to quantify neutrophil infiltration, NETosis potential, iNETs, cerebral perfusion, and infarction. In addition, NET markers were assessed in the blood of aneurysmal SAH patients. In mice, SAH led to brain neutrophil infiltration within 24 hours, induced a pro-NETosis phenotype selectively in skull neutrophils, and caused a significant increase in iNETs by day 1, which persisted until at least day 7. Neutrophil depletion significantly reduced iNETs, improving cerebral perfusion, leading to less neurological deficits and less incidence of DCI (16% versus 51.9%). Similarly, PAD4 inhibition reduced iNETs, improved neurological outcome, and reduced incidence of DCI (5% versus 30%), whereas degrading NETs marginally improved outcomes. Patients with aneurysmal SAH who developed DCI had elevated markers of NETs compared with non-DCI patients. After SAH, skull-derived neutrophils are primed for NETosis, and there are persistent brain iNETs, which correlated with delayed deficits. The findings from this study suggest that, after SAH, neutrophils and NETosis are therapeutic targets, which can prevent vascular occlusion by NETs in the brain, thereby lessening the risk of DCI. Finally, NET markers may be biomarkers, which can predict which patients with aneurysmal SAH are at risk for developing DCI.

Retracted: Aquaporin 4 Depolarization-Enhanced Transferrin Infiltration Leads to Neuronal Ferroptosis after Subarachnoid Hemorrhage in Mice.

[This retracts the article DOI: 10.1155/2022/8808677.].

Incidence and factors in delayed neurological deficits after subarachnoid hemorrhage in mice

ObjectiveDelayed cerebral ischemia (DCI) is one of the most feared complications in aneurysmal subarachnoid hemorrhage (SAH). Animal models are crucial to studying the disease mechanisms and potential treatments. DCI in rodents was thought to not exist; herein we examine literature and our experience with DCI in rodents. MethodsDaily behavioral performance was assessed every day from day 1 to up to 7 days post-SAH on mice from 5 different studies that used the endovascular perforation model. Performance was graded using an 8-test sensorimotor neuroscore previously described. The daily neuroscore was then used to identify the incidence and timing of delayed neurological deficits (DND), a clinical surrogate for DCI. A total number of 298 mice (134 males, 164 females) were subjected to SAH. Fifty-one mice had histological staining done to identify infarct volume. ResultsThe overall incidence of DND was 33.9%; 27.6% in males and 39.0% in females, but this difference was not statistically significant. The overall incidence of delayed death was 21.1%, and there was no significant difference for delayed mortality in females versus male mice. There is a non-statistically significant trend towards increased infarct volume in mice suffering DND. ConclusionsMice with endovascular puncture induced SAH develop DND at rates comparable to human patients. Future work needs to correlate the DND seen with decreased regional cerebral blood flow, another hallmark of DCI, but in spite of this need, researchers may use the murine models to test therapies for DCI after SAH.

Ly6C-high monocytes alleviate brain injury in experimental subarachnoid hemorrhage in mice

BackgroundSubarachnoid hemorrhage (SAH) is an uncommon type of potentially fatal stroke. The pathophysiological mechanisms of brain injury remain unclear, which hinders the development of drugs for SAH. We aimed to investigate the pathophysiological mechanisms of SAH and to elucidate the cellular and molecular biological response to SAH-induced injury.MethodsA cross-species (human and mouse) multiomics approach combining high-throughput data and bioinformatic analysis was used to explore the key pathophysiological processes and cells involved in SAH-induced brain injury. Patient data were collected from the hospital (n = 712). SAH was established in adult male mice via endovascular perforation, and flow cytometry, a bone marrow chimera model, qPCR, and microglial depletion experiments were conducted to explore the origin and chemotaxis mechanism of the immune cells. To investigate cell effects on SAH prognosis, murine neurological function was evaluated based on a modified Garcia score, pole test, and rotarod test.ResultsThe bioinformatics analysis confirmed that inflammatory and immune responses were the key pathophysiological processes after SAH. Significant increases in the monocyte levels were observed in both the mouse brains and the peripheral blood of patients after SAH. Ly6C-high monocytes originated in the bone marrow, and the skull bone marrow contribute a higher proportion of these monocytes than neutrophils. The mRNA level of Ccl2 was significantly upregulated after SAH and was greater in CD11b-positive than CD11b-negative cells. Microglial depletion, microglial inhibition, and CCL2 blockade reduced the numbers of Ly6C-high monocytes after SAH. With CCR2 antagonization, the neurological function of the mice exhibited a slow recovery. Three days post-SAH, the monocyte-derived dendritic cell (moDC) population had a higher proportion of TNF-α-positive cells and a lower proportion of IL-10-positive cells than the macrophage population. The ratio of moDCs to macrophages was higher on day 3 than on day 5 post-SAH.ConclusionsInflammatory and immune responses are significantly involved in SAH-induced brain injury. Ly6C-high monocytes derived from the bone marrow, including the skull bone marrow, infiltrated into mouse brains via CCL2 secreted from microglia. Moreover, Ly6C-high monocytes alleviated neurological dysfunction after SAH.

GPNMB Ameliorates Neuroinflammation Via the Modulation of AMPK/NFκB Signaling Pathway After SAH in Mice

Glycoprotein non-metastatic melanoma protein B (GPNMB) got its name from the first discovery in a cell line of non-metastatic melanoma. Later studies found that GPNMB is widely expressed in various tissues and cells of the human body, most abundant in neural tissue, epithelial tissue, bone tissue, and monocyte-macrophage system. GPNMB has been shown to have anti-inflammatory effects in a variety of neurological diseases, however, it has not been reported in subarachnoid hemorrhage (SAH). Male CD-1 mice were used and intra-arterial puncture method was applied to establish the SAH model. Exogenous recombinant GPNMB (rGPNMB) was injected intracerebroventricularly 1 h after SAH. SAH grading, brain edema and blood–brain barrier (BBB) integrity were quantified, and neurobehavioral tests were performed to evaluate the effect of GPNMB on the outcome. Dorsomorphin, the selective inhibitor on AMPK was introduced to study the downstream signaling through which the GPNMB works. Furthermore, western blot, immunofluorescence staining and ELISA were utilized to confirm the signaling. After SAH, GPNMB expression increased significantly as a result of the inflammatory response. GPNMB was expressed extensively in mouse microglia, astrocytes and neurons. The administration of rGPNMB could alleviate brain edema, restore BBB integrity and improve the neurological outcome of mice with SAH. GPNMB treatment significantly magnified the expression of p-AMPK while p-NFκB, IL-1β, IL-6 and TNF-α were suppressed; in the meantime, the combined administration of GPNMB and AMPK inhibitor could decrease the intensity of p-AMPK and reverse the quantity of p-NFκB and the above inflammatory cytokines. GPNMB has the potential of ameliorating the brain edema and neuroinflammation, protecting the BBB and improving the neurological outcome, possibly via the AMPK/NFκB signaling pathway.Graphical

Norad Competently Binds with Pum2 to Regulate Neuronal Apoptosis and Play a Neuroprotective Role After SAH in Mice

Subarachnoid Hemorrhage (SAH) is a cerebrovascular disorder that has been found to have severe consequences, including a high mortality and disability rate. Research has indicated that neuronal death, particularly apoptosis, plays a major role in the neurological impairment that follows SAH. RNA-binding protein Pum2 can interfere with translation or other biological functions by connecting to the UGUAHAUA sequence on RNA. Noncoding RNA activated by DNA damage (Norad) contains some Pum2 recognition sequences, which may bind to Pum2 protein and affect its capacity to attach to target mRNA. The time course expression of Norad and Pum2 after SAH is analyzed by establishing a mouse SAH model. Subsequently, the purpose of this study is to investigate the potential role and mechanism of the Norad-Pum2 axis after SAH using lentivirus overexpression of Pum2 and knockdown of Norad. Analysis of Pum2 and Norad levels reveal that the former is significantly reduce and the latter is significantly increased in the SAH group compared to the sham group. Subsequent overexpression of Pum2 and Norad knockdown is found to reduce SAH-induced oxidative stress, neuronal apoptosis, and ultimately improve behavioral and cognitive changes in SAH mice. Our study indicates that Norad-Pum2 acts as a neuromodulator in SAH, and that by increasing Pum2 and decreasing Norad levels, SAH-induced neuronal apoptosis can be reduced and neurological deficits alleviated. Consequently, Norad-Pum2 may be a promising therapeutic target for SAH.

Effect of Ginseng Extract Ginsenoside Rg1 on Mice with Intracerebral Injury

Background: Traditional Chinese medicine has a long history of treating intracerebral injury. The aim of this research is to test the hypothesis that Ginsenoside Rg1 can alleviate brain injury in subarachnoid hemorrhage (SAH) mice. Methods: SAH mice were induced by autologous blood injection into cisterna magna, the mortality and neurological function were assessed. Ginsenoside Rg1 was administered continuously for seven days after SAH. Then, Y-maze test was used to detect the neurological deficits. Brains were harvested to evaluate the neuroinflammation of SAH by immunofluorescence staining and flow cytometry. Cerebral vasospasm was evaluated by hematoxylin-eosin (HE) staining, and neuronal apoptosis was evaluated by TdT-mediated dUTP Nick-End Labeling (TUNEL) staining and HE staining. Results: We demonstrate that Ginsenoside Rg1 reduced mortality and improved neurological deficits, reduced inflammatory response, ameliorated cerebral vasospasm and neuronal apoptosis after SAH. Conclusion: Ginsenoside Rg1 can alleviate brain damage after SAH in mice.

Role of Protein Tyrosine Phosphatase 1B Inhibitor in Early Brain Injury of Subarachnoid Hemorrhage in Mice.

Clinically, early brain injury (EBI), which refers to the acute injuries to the whole brain in the phase of the first 72 h following subarachnoid hemorrhage (SAH), is intensely investigated to improve neurological and psychological function. Additionally, it will be meaningful to explore new therapeutic approaches for EBI treatment to improve the prognosis of patients with SAH. To investigate the underlying neuroprotection mechanism in vitro, the Protein tyrosine phosphatase 1B inhibitor (PTP1B-IN-1) was put in primary neurons induced by OxyHb to observe neuroapoptosis, neuroinflammation, and ER stress. Then, one hundred forty male mice were subjected to Experiment two and Experiment three. The mice in the SAH24h + PTP1B-IN-1 group were given an intraperitoneal injection of 5 mg/kg PTP1B-IN-1 30 min before anesthesia. SAH grade, neurological score, brain water content, Western blot, PCR, and Transmission Electron Microscopy (TEM) were performed to observe the underlying neuroprotection mechanism in vivo. Overall, this study suggests that PTP1B-IN-1 could ameliorate neuroapoptosis, neuroinflammation, and ER stress in vitro and in vivo by regulating the IRS-2/AKT signaling pathway, suggesting that PTP1B-IN-1 may be a candidate drug for the treatment of early brain injury after SAH.

Epidermal Growth Factor Receptor Mediates Neuronal Apoptosis After Subarachnoid Hemorrhage in Mice.

Early brain injury including neuronal apoptosis is a main contributor to neurological deterioration after subarachnoid hemorrhage (SAH). This study was aimed to investigate whether EGFR (epidermal growth factor receptor)/NFκB (nuclear factor-kappa B) inducing kinase (NIK)/NFκB (p65 and p50) pathway is involved in the neuronal apoptosis after SAH in mice. C57BL/6 adult male mice underwent endovascular perforation SAH modeling or sham-operation (n=286), and 86 mild SAH mice were excluded. In experiment 1, vehicle or an EGFR inhibitor (632.0 ng AG1478) was administered intraventricularly at 30 minutes postmodeling. At 24 or 72 hours, after neurological score was tested, brain water content, double immunolabeling with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and a neuronal marker antimicrotubule-associated protein-2 antibody, Western blotting using whole tissue lysate or nuclear protein extraction of the left cortex, and immunohistochemistry for cleaved caspase-3, phosphorylated (p-) EGFR, NIK, p-NFκB p65, and NFκB p105/50 were evaluated. In experiment 2, after sham or SAH modeling, AG1478+vehicle or AG1478+4.0 ng EGF was administered intraventricularly. The brain was used for TUNEL staining and immunohistochemistry after 24-hour observation. SAH group showed deteriorated neurological score (P<0.01, Mann-Whitney U test), more TUNEL- and cleaved caspase-3-positive neurons (P<0.01, ANOVA), and higher brain water content (P<0.01, Mann-Whitney U test), and these observations were improved in SAH-AG1478 group. Western blotting showed that expression levels of p-EGFR, p-p65, p50, and nuclear-NIK were increased after SAH (P<0.05, ANOVA), and decreased by AG1478 administration. Immunohistochemistry revealed these molecules localized in degenerating neurons. EGF administration resulted in neurological deterioration, increased TUNEL-positive neurons, and activation of EGFR, NIK, and NFκB. Activated EGFR, nuclear-NIK, and NFκB expressions were observed in cortical degenerating neurons after SAH, and were decreased by administration of AG1478, associated with suppression of TUNEL- and cleaved caspase-3-positive neurons. EGFR/NIK/NFκB pathway is suggested to be involved in neuronal apoptosis after SAH in mice.

473 Role of Neutrophils and Neutrophil Extracellular Traps in Subarachnoid Hemorrhage in Mice

INTRODUCTION: Aneurysmal subarachnoid hemorrhage (aSAH) continues to be a devastating disease. The role of neutrophils and neutrophil extracellular traps (NETs) have been investigated in other cerebrovascular disorders. Recent evidence suggest that neutrophils might play a role in outcomes after aSAH. METHODS: Subarachnoid hemorrhage model: The endovascular perforation model was utilized to induce SAH in mice. Flow cytometry: Flow cytometry technique was utilized to quantify neutrophils. Neutrophils were identified as CD45+Cd11b+Ly6G+ cells. NETosis assay: Neutrophils were assayed for their NETosis potential using a previously described method. The ratio of PMA (SYTOX+) to DMSO (SYTOX+) defined the NETosis induction. RNAseq: RNA sequencing was performed on neutrophils isolated from skull and femur bone marrow. Immunohistochemistry: NETs were assessed using classical IHC techniques and in vivo microscopy. Neurobehavior score: Mice were assessed daily for their behavior score using previously reported techniques. RESULTS: Neutrophils infiltrate brain within 24 hours and normalize by day 5. RNAseq demonstrates segregation of skull and femur bone marrow neutrophils following SAH. SAH induces a NETosis phenotype in skull neutrophils. NETs form starting day 1 after injury and persist until at least day 7. Neutrophil depletion and NETs inhibition attenuates early brain injury after SAH. Patients developing DCI have significantly higher blood markers of NETs. CONCLUSIONS: Neutrophils infiltrate the brain within the first 24 hours with NETs forming as early as day 1. Depletion of neutrophils and NET inhibition mitigated early brain injury following SAH. Blood markers of NETs are elevated in DCI patients and may be used as predictors of DCI. This highlights NETs as potential therapeutic target for patients with SAH and paves the way for future studies.

Cisterna Magna Injection Mouse Model of Subarachnoid Hemorrhage (SAH): A Systematic Literature Review of Preclinical SAH Research

Objective: This review article describes the characteristics of published literature using the cisterna magna blood injection mouse model of subarachnoid hemorrhage (SAH) with the aim to define particular standards and identify moderators of mortality rate, SAH grade, and large artery vasospasm. Methods: We searched for English-original peer-reviewed studies which reported the induction of SAH in mice via single or multiple blood injections into the cisterna magna. The search included studies published until 13th February 2023 on PubMed, Embase and Web of Science. Furthermore, we investigated the reporting of mortality rate, vasospasms by measuring large arteries, and SAH grade in cisterna magna blood injection mouse model. Results: Seven articles out of 136 identified records matched our inclusion criteria and were therefore included in descriptive analysis. Four articles reported the mortality rate which varied between zero and 22 percent. Five articles displayed vasospasms of large cerebral arteries including basilar artery (BA), anterior cerebral artery (ACA), and middle cerebral artery (MCA). Interestingly, the diameters of the observed arteries started to decrease already within the first hour after blood injection and achieved the lowest values at different times, but mainly between six and twelve hours after SAH induction. The artery diameters reached nearly their pre-SAH (control group) diameters approximately after four to seven days after SAH. However, the SAH severity grade was reported in none of these publications. No uniform model characteristics were observed in current literature. Conclusion: A systemic overview of the cisterna magna blood injection mouse model of SAH is presented. An important heterogeneity was observed. Hence, standardized model features and study endpoints have to be defined in order to improve reporting frequency and quality to enhance the reproducibility of preclinical SAH research in the future.

Anti-Apoptotic Effects of AMPA Receptor Antagonist Perampanel in Early Brain Injury After Subarachnoid Hemorrhage in Mice.

This study was aimed to investigate if acute neuronal apoptosis is induced by activation of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionate) receptors (AMPARs) and inhibited by a clinically available selective AMPAR antagonist and antiepileptic drug perampanel (PER) in subarachnoid hemorrhage (SAH), and if the mechanisms include upregulation of an inflammation-related matricellular protein periostin. Sham-operated and endovascular perforation SAH mice randomly received an administration of 3mg/kg PER or the vehicle intraperitoneally. Post-SAH neurological impairments and increased caspase-dependent neuronal apoptosis were associated with activation of AMPAR subunits GluA1 and GluA2, and upregulation of periostin and proinflammatory cytokines interleukins-1β and -6, all of which were suppressed by PER. PER also inhibited post-SAH convulsion-unrelated increases in the total spectral power on video electroencephalogram (EEG) monitoring. Intracerebroventricularly injected recombinant periostin blocked PER's anti-apoptotic effects on neurons. An intracerebroventricular injection of a selective agonist for GluA1 and GluA2 aggravated neurological impairment, neuronal apoptosis as well as periostin upregulation, but did not increase the EEG total spectral power after SAH. A higher dosage (10mg/kg) of PER had even more anti-apoptotic effects compared with 3mg/kg PER. Thus, this study first showed that AMPAR activation causes post-SAH neuronal apoptosis at least partly via periostin upregulation. A clinically available AMPAR antagonist PER appears to be neuroprotective against post-SAH early brain injury through the anti-inflammatory and anti-apoptotic effects, independent of the antiepileptic action, and deserves further study.