Experimental Subarachnoid Hemorrhage Model Research Articles

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.

Effect of Intrathecal Eugenol on Cerebral Vasospasm in an Experimental Subarachnoid Hemorrhage Model

Eugenol has various curative properties. It affects the dilatation of cerebral arteries through voltage-dependent Ca2+ channel inhibition. This study is the first to explore the impact of eugenol on neuroprotection and vasospasm in an experimental subarachnoid hemorrhage (SAH) model. Twenty-four adult male Sprague-Dawley rats were indiscriminately separated into 3 groups: the control group (n=8), the SAH group (n=8), and the eugenol group (n=8). A double-bleeding method was used. The eugenol group received intracisternal eugenol (Sigma-Aldrich, St. Louis, MO, USA) at 30μg/20μl after induction of SAH. On the day 7, all groups were euthanized. Measurements were taken for basilar artery wall thickness, lumen diameter, serum endothelin-1 (ET-1), and caspase-3 levels. The eugenol group exhibited significantly lower wall thickness, ET-1, oxidative stress index, and caspase-3 levels compared to the SAH group. In comparison to the control group, the eugenol group showed a higher oxidative stress index along with higher ET-1 and caspase-3 levels, but these differences were not statistically significant. Wall thickness was significantly higher in the eugenol group than in the control group. This study represents the first literature exploration of intrathecal eugenol's impact on vasospasm induced after experimental SAH. Administration of intrathecal eugenol demonstrates a positive effect on the treatment of experimental vasospasm as well as on the reduction of oxidative stress and apoptosis.

Galectin-3 modulates microglial activation and neuroinflammation in early brain injury after subarachnoid hemorrhage

BackgroundAneurysmal subarachnoid hemorrhage (SAH) is a devastating acute cerebrovascular event with high mortality and permanent disability rates. Higher galectin-3 levels on days 1–3 have been shown to predict the development of delayed cerebral infarction or adverse outcomes after SAH. Recent single-cell analysis of microglial transcriptomic diversity in SAH revealed that galectin could influence the development and course of neuroinflammation after SAH. MethodsThis study aimed to investigate the role and mechanism of galectin-3 in SAH and to determine whether galectin-3 inhibition prevents early brain injury by reducing microglia polarization using a mouse model of SAH and oxyhemoglobin-treated activation of mouse BV2 cells in vitro. ResultsWe found that the expression of galectin-3 began to increase 12 h after SAH and continued to increase up to 72 h. Importantly, TD139-inhibited galectin-3 expression reduced the release of inflammatory factors in microglial cells. In the experimental SAH model, TD139 treatment alleviated neuroinflammatory damage after SAH and improved defects in neurological functions. Furthermore, we demonstrated that galectin-3 inhibition affected the activation and M1 polarization of microglial cells after SAH. TD139 treatment inhibited the expression of TLR4, p-NF-κB p65, and NF-κB p65 in microglia activated by oxyhemoglobin as well as eliminated the increased expression and phosphorylation of JAK2 and STAT3. ConclusionThese findings suggest that regulating microglia polarization by galectin-3 after SAH to improve neuroinflammation may be a potential therapeutic target.

Investigation of the protective effects of piceatannol on experimental subarachnoid hemorrhage in rats.

Subarachnoid hemorrhage (SAH) is one of the most prevalent brain injuries in humans which has poor prognosis and high mortality rates. Due to several medical or surgical treatment methods, a gold standard method doesn't exist for SAH treatment. Piceatannol (PCN), a natural analog of resveratrol, was reported to reduce inflammation and apoptosis promising a wide range of therapeutic alternatives. In this study, we aimed to investigate the effects of PCN in an experimental SAH model. The alleviating effects of PCN in the hippocampus in an experimental SAH model were investigated for the first time. In this study, 27 Wistar Albino male rats (200-300g; 7-8week) were used. Animals were divided into three groups; SHAM, SAH, and SAH + PCN. SAH model was created with 120µl of autologous arterial tail blood to prechiasmatic cisterna. 30mg/kg PCN was administered intraperitoneally at 1st h after SAH. Neurological evaluation was performed with Garcia's score. RT-PCR was performed for gene expression levels in the hippocampus. Pyknosis, edema, and apoptosis were evaluated by H&E and TUNEL staining. Our results indicated that PCN administration reduced apoptosis (P < 0.01), cellular edema, and pyknosis (P < 0.05) in the hippocampus after SAH. Moreover, PCN treatment significantly decreased the expression levels of TNF-α (P < 0.01), IL-6 (P < 0.05), NF-κB (P < 0.05), and Bax (P < 0.05) in the hippocampus. Our results demonstrated that PCN might be a potential therapeutic adjuvant agent for the treatment of early brain injury (EBI) following SAH. Further studies are required to clarify the underlying mechanisms and treatment options of SAH.

Recombinant soluble form of receptor for advanced glycation end products ameliorates microcirculation impairment and neuroinflammation after subarachnoid hemorrhage

Impaired cerebral microcirculation after subarachnoid hemorrhage (SAH) has been shown to be related to delayed ischemic neurological deficits (DIND). We previously demonstrated the involvement of the receptor for advanced glycation end products (RAGE) in the pathogenesis of SAH related neuronal death. In the present study, we aimed to investigate the therapeutic effects of a recombinant soluble form of RAGE (sRAGE) on microcirculation impairment following SAH. Intrathecal injection of autologous blood in rats, mixed primary astrocyte and microglia cultures exposed to hemolysates and endothelial cells ​(ECs) from human brain microvascular exposed to glia-conditioned medium or SAH patient's CSF were used as experimental SAH models in vivo and in vitro. The results indicated that intrathecal administration of recombinant sRAGE significantly ameliorated the vasoconstriction of cortical arterioles and associated perfusion impairment, brain edema, reduced cell death, endothelial dysfunction, and improved motor performance at 24 and 48 ​h after SAH induction in rats. The in vitro results further showed that recombinant sRAGE significantly reduced astrocyte swelling and microglia activation, in parallel with decreased mRNA expression levels of pro-inflammatory cytokines including interleukin-6 (IL-6) and interleukin-1β (IL-1β) in vitro. Moreover, the in vitro model of SAH-induced p-eNOS and eNOS suppression, along with stress fiber formation in brain microvascular ECs, was effectively reversed by sRAGE treatment and led to a decrease in cleaved-caspase 3 expression. In summary, recombinant sRAGE effectively lessened microcirculation impairment and vascular injury after SAH via the mechanism of anti-inflammation, which may provide a potential therapeutic strategy for SAH.

Investigation of the effect of carnitine on cerebral vasospasm in experimental subarachnoid hemorrhage model

The vasospasm, which develops after subarachnoid hemorrhage (SAH), is an unenlightened table in terms of etiology and results. It is usually associated with decreased perfusion, which is associated with decreased blood flow distal to the affected artery and can be demonstrated radiologically. Acetyl-L-carnitine (ALCAR) can be found in brain tissue and easily crosses the blood–brain barrier. Therefore, in this study, we aimed to investigate the therapeutic efficacy of ALCAR, which is an effective antioxidant amine, on vasospasm development after experimental SAH. In our study, 35 adults male Wistar RATs weighing between 235–250 g were used. These RATs were divided into five groups with n = 7. Group 1 Control group, Group 2 SAH + SF (carrier solution), Group 3 SAH + ALCAR 50 mg\\kg intraperitoneally, Group 4 SAH + ALCAR 100 mg\\kg intraperitoneally and Group 5 SAH. Subarachnoid hemorrhage was induced by giving autologous arterial blood to the cisterna magna of the animals in groups 2, 3, 4, and 5. At 0.-12.- 24.- 36.- 48.- 60. and 72. h, Group 2 was injected with SF, Group 3 with intraperitoneally ALCAR 50 mg\\kg, and Group 4 with intraperitoneally ALCAR 100 mg\\kg, respectively. Following perfusion and fixation, the animals were subjected to a wide craniectomy, and the brain, cerebellum, and brain stems were removed globally. Then, sections were taken from the basilar arteries of all animals and photographed at 40X magnification. Basilar artery lumen cross-sectional areas, basilar artery areas, and wall thicknesses were measured from these sections. The basilar artery lumen cross-sectional area was found to be significantly larger in the groups in which SAH was formed and ALCAR 50 mg\\kg and ALCAR 100 mg\\kg were given compared to the group with only SAH and SAH + SF (p = 0.0408). Basilar artery wall thickness increased in all groups except the control group (p < 0.05). In light of all these findings, it was concluded in our study that Carnitine was effective in the resolution of vasospasm in the experimental SAH model.

Multimodal imaging of the role of hyperglycemia following experimental subarachnoid hemorrhage

Hyperglycemia has been linked to worsening outcomes after subarachnoid hemorrhage (SAH). Nevertheless, the mechanisms involved in the pathogenesis of SAH have been scarcely evaluated so far. The role of hyperglycemia was assessed in an experimental model of SAH by T2 weighted, dynamic contrast-enhanced magnetic resonance imaging (T2W and DCE-MRI), [18F]BR-351 PET imaging and immunohistochemistry. Measures included the volume of bleeding, the extent of cerebral infarction and brain edema, blood brain barrier disruption (BBBd), neutrophil infiltration and matrix metalloprotease (MMP) activation. The neurofunctional outcome, neurodegeneration and myelinization were also investigated. The induction of hyperglycemia increased mortality, the size of the ischemic lesion, brain edema, neurodegeneration and worsened neurological outcome during the first 3 days after SAH in rats. In addition, these results show for the first time the exacerbating effect of hyperglycemia on in vivo MMP activation, Intercellular Adhesion Molecule 1 (ICAM-1) expression and neutrophil infiltration together with increased BBBd, bleeding volume and fibrinogen accumulation at days 1 and 3 after SAH. Notably, these data provide valuable insight into the detrimental effect of hyperglycemia on early BBB damage mediated by neutrophil infiltration and MMP activation that could explain the worse prognosis in SAH.

Restoring System xc- activity by xCT overexpression inhibited neuronal ferroptosis and improved neurological deficits after experimental subarachnoid hemorrhage

BackgroundFerroptosis is an important therapeutic target to alleviate early brain injury (EBI) after subarachnoid hemorrhage (SAH), yet the mechanism of neuronal ferroptosis after SAH remains unclear. System xc- dysfunction is one of the key pathways to induce ferroptosis. System xc- activity is mainly regulated by the expression of xCT. This study was designed to investigate the effect of xCT expression and System xc- activity on ferroptosis and EBI in an experimental SAH model both in vitro and in vivo. MethodsSAH was induced in adult male Sprague-Dawley rats by injecting autologous blood into the prechiasmatic cistern. Primary neurons treated with oxyhemoglobin (10 µM) were used to mimic SAH in vitro. Plasmid transfection was used to induce xCT overexpression. Western blotting, immunofluorescence staining, measurement of cystine uptake, enzyme-linked immunosorbent assay, transmission electron microscopy, Nissl staining, and a series of neurobehavioral tests were conducted to explore the role of xCT and System xc- activity in ferroptosis and EBI after SAH. ResultsWe found that System xc- dysfunction induced ferroptosis and exacerbated EBI after SAH in rats. xCT deficiency after SAH resulted in System xc- dysfunction, weakened neuronal antioxidant capacity and activated neuronal ferroptosis. xCT overexpression improved neuronal antioxidant capacity and inhibited neuronal ferroptosis by restoring System xc- activity. Rats with xCT overexpression after SAH presented with attenuated brain edema and inflammation, increased neuronal survival, and ameliorated neurological deficits. ConclusionsOur study revealed that restoring System xc- activity by xCT overexpression inhibited neuronal ferroptosis and EBI and improved neurological deficits after SAH.

Edaravone Dexborneol Treatment Attenuates Neuronal Apoptosis and Improves Neurological Function by Suppressing 4-HNE-Associated Oxidative Stress After Subarachnoid Hemorrhage.

Edaravone dexborneol is a novel neuroprotective drug that comprises edaravone and (+)-borneol in a 4:1 ratio. Phase II and III studies have demonstrated that Chinese patients treated with edaravone dexborneol within 48 h of AIS onset have better functional outcomes than those treated with edaravone alone. However, the effect of edaravone dexborneol on subarachnoid hemorrhage (SAH) has not yet been elucidated. This study aimed to investigate the therapeutic effects of edaravone dexborneol on SAH-induced brain injury and long-term behavioral deficits and to explore the possible mechanisms. The experimental rat SAH model was induced by an intraluminal puncture of the left middle cerebral artery (MCA). Edaravone dexborneol or edaravone at a clinical dose was infused into the tail vein for 3 days post-SAH surgery. Behavioral outcomes were assessed by a modified Garcia scoring system and rotarod, foot-fault, and corner tests. Immunofluorescence, Western blot, and ELISA methods were used to evaluate neuronal damage and oxidative stress. Our results showed that a post-SAH therapeutic regimen with edaravone dexborneol helped improve neurological function up to 21 days after SAH surgery and demonstrated a greater beneficial effect than edaravone alone, accompanied by an obvious inhibition of neuronal apoptosis in the CA1 hippocampus and basal cortex regions. Mechanistically, edaravone dexborneol not only suppressed the lipid peroxidation product malondialdehyde (MDA) but also improved the total antioxidant capability (TAC) 3 days after SAH. Notably, edaravone dexborneol treatment significantly inhibited the expression of another lipid peroxidation product, 4-hydroxynonenal (4-HNE), in the CA1 hippocampus and basal cortex, which are vital participants in the process of neuronal oxidative damage and death after SAH because of their acute cytotoxicity. Together, our results demonstrate that edaravone dexborneol confers neuroprotection and stabilizes long-term behavioral ability after SAH injury, possibly by suppressing 4-HNE-associated oxidative stress. These results may help develop new clinical strategies for SAH treatment.

Targeting iNOS Alleviates Early Brain Injury After Experimental Subarachnoid Hemorrhage via Promoting Ferroptosis of M1 Microglia and Reducing Neuroinflammation.

Numerous studies have demonstrated the role of neuroinflammation in mediating acute pathophysiological events of early brain injury after subarachnoid hemorrhage (SAH). However, it is not clear how to target this inflammatory cascade after SAH. M1 activation of microglia is an important pathological mechanism driving neuroinflammation in SAH, which is considered aggressive, leading to cytotoxicity and robust inflammation related to the release of proinflammatory cytokines and chemokines after SAH. Thus, reducing the number of M1 microglia represents a potential target for therapies to improve outcomes after SAH. Previous studies have found that inducible nitric oxide synthase (iNOS/NO•) plays an essential role in promoting the survival of M1 microglia by blocking ferroptosis. Ferroptosis is a new type of iron-dependent cellular procedural death associated with pathological cell death related to mammalian degenerative diseases, cerebral hemorrhage, and traumatic brain injury. Here, we investigated the effect of L-NIL, an inhibitor of iNOS, on M1 microglia, neuroinflammation, neuronal cell death, brain edema, and neurological function in an experimental SAH model in vivo and in vitro. We found that L-NIL reduced the number of M1 microglia and alleviated neuroinflammation following SAH. Notably, treatment with L-NIL relieves brain edema and neuronal injury and improves outcomes of neurological function after SAH in rats. Mechanistically, we found that L-NIL inhibited the expression of iNOS and promoted ferroptosis of M1 microglia by increasing the expression of ferroptosis-related proteins and lipid peroxidation in an in vitro model of SAH, which was reversed by a ferroptosis inhibitor, liproxstatin-1. In addition, inhibiting iNOS had no significant effect on ferroptosis of neurons after oxyhemoglobin stimulation in vitro. Thus, our research demonstrated that inhibition of iNOS might represent a potential therapeutic strategy to improve outcomes after SAH by promoting ferroptosis of M1 microglia and reducing neuroinflammation.

ACEA Attenuates Oxidative Stress by Promoting Mitophagy via CB1R/Nrf1/PINK1 Pathway after Subarachnoid Hemorrhage in Rats.

Method Endovascular perforation was performed to establish a SAH model of rats. ACEA was administered intraperitoneally 1 h after SAH. The CB1R antagonist AM251 was injected intraperitoneally 1 h before SAH induction. Adenoassociated virus- (AAV-) Nrf1 shRNA was infused into the lateral ventricle 3 weeks before SAH induction. Neurological tests, immunofluorescence, DHE, TUNEL, Nissl staining, transmission electron microscopy (TEM), and Western blot were performed. Results The expression of CB1R, Nrf1, PINK1, Parkin, and LC3II increased and peaked at 24 h after SAH. ACEA treatment exhibited the antioxidative stress and antiapoptosis effects after SAH. In addition, ACEA treatment increased the expression of Nrf1, PINK1, Parkin, LC3II, and Bcl-xl but repressed the expression of Romo-1, Bax, and cleaved caspase-3. Moreover, the TEM results demonstrated that ACEA promoted the formation of mitophagosome and maintained the normal mitochondrial morphology of neurons. The protective effect of ACEA was reversed by AM251 and Nrf1 shRNA, respectively. Conclusions This study demonstrated that ACEA alleviated oxidative stress and neurological dysfunction by promoting mitophagy after SAH, at least in part via the CB1R/Nrf1/PINK1 signaling pathway.

Trigeminal Nerve Stimulation Improves Cerebral Macrocirculation and Microcirculation After Subarachnoid Hemorrhage: An Exploratory Study.

Delayed cerebral ischemia (DCI) is the most consequential secondary insult after aneurysmal subarachnoid hemorrhage (SAH). It is a multifactorial process caused by a combination of large artery vasospasm and microcirculatory dysregulation. Despite numerous efforts, no effective therapeutic strategies are available to prevent DCI. The trigeminal nerve richly innervates cerebral blood vessels and releases a host of vasoactive agents upon stimulation. As such, electrical trigeminal nerve stimulation (TNS) has the capability of enhancing cerebral circulation. To determine whether TNS can restore impaired cerebral macrocirculation and microcirculation in an experimental rat model of SAH. The animals were randomly assigned to sham-operated, SAH-control, and SAH-TNS groups. SAH was induced by endovascular perforation on Day 0, followed by KCl-induced cortical spreading depolarization on day 1, and sample collection on day 2. TNS was delivered on day 1. Multiple end points were assessed including cerebral vasospasm, microvascular spasm, microthrombosis, calcitonin gene-related peptide and intercellular adhesion molecule-1 concentrations, degree of cerebral ischemia and apoptosis, and neurobehavioral outcomes. SAH resulted in significant vasoconstriction in both major cerebral vessels and cortical pial arterioles. Compared with the SAH-control group, TNS increased lumen diameters of the internal carotid artery, middle cerebral artery, and anterior cerebral artery, and decreased pial arteriolar wall thickness. Additionally, TNS increased cerebrospinal fluid calcitonin gene-related peptide levels, and decreased cortical intercellular adhesion molecule-1 expression, parenchymal microthrombi formation, ischemia-induced hypoxic injury, cellular apoptosis, and neurobehavioral deficits. Our results suggest that TNS can enhance cerebral circulation at multiple levels, lessen the impact of cerebral ischemia, and ameliorate the consequences of DCI after SAH.

Letter to the Editor Regarding “Aneurysm Location as a Prognostic Outcome Factor After Subarachnoid Hemorrhage from Internal Carotid Artery Aneurysms and Potential Impact for Further Experimental Subarachnoid Hemorrhage Models”

Letter to the Editor Regarding “Aneurysm Location as a Prognostic Outcome Factor After Subarachnoid Hemorrhage from Internal Carotid Artery Aneurysms and Potential Impact for Further Experimental Subarachnoid Hemorrhage Models”

COG133 Attenuates the Early Brain Injury Induced by Blood-Brain Barrier Disruption in Experimental Subarachnoid Hemorrhage.

Subarachnoid hemorrhage (SAH) is a kind of severe hemorrhagic stroke, and early brain injury acted as one of the main causes of death and delayed neurological deficit in patients with subarachnoid hemorrhage. In this process, the function and structural integrity of the blood-brain barrier play an important role. In this study, we have observed whether the apolipoprotein E (apoE) mimetic peptide, COG133, can alleviate early brain injury after subarachnoid hemorrhage. For this purpose, an experimental subarachnoid hemorrhage model was constructed in mice and treated by intravenous injection of COG133 at a dosage of 1 mg/kg. Then, the function and integrity of the blood-brain barrier were detected, and the pyroptosis level of the neuron was determined. The results showed that COG133 could protect blood-brain barrier function and structure integrity, reduce early brain injury, and ameliorate neurological function after subarachnoid hemorrhage. In terms of molecular mechanism, COG133 inhibits blood-brain barrier destruction through the proinflammatory CypA-NF-κB-MMP9 pathway and reduces neuronal pyroptosis by inhibiting NLRP3 inflammasome activation. In conclusion, this study demonstrated that apoE-mimetic peptide, COG133, can play a neuroprotective role by protecting blood-brain barrier function and inhibiting brain cell pyroptosis to reduce early brain injury after subarachnoid hemorrhage.

Ferritinophagy is Involved in Experimental Subarachnoid Hemorrhage-Induced Neuronal Ferroptosis.

Ferroptosis is a novel form of regulated cell death involved in the pathophysiological process of experimental subarachnoid hemorrhage (SAH), but how neuronal ferroptosis occurs remains unknown. In this study, we report that SAH-induced ferroptosis is macroautophagy/autophagy dependent because the inhibition of autophagy by knocking out autophagy-related gene 5 (ATG5) apparently mitigated SAH-induced ferroptosis. We created an experimental SAH model in Sprague-Dawley rats to determine the possible mechanism. We found that SAH can trigger neuronal ferroptosis, as evidenced by the disruption of ironhomeostasis, elevation of intracellular lipid peroxidation (LPO) and decreased expression of ferroptosis-protective proteins. Then, we inhibited autophagy byATG5gene knockout, showing thatautophagy inhibition can reduce the intracellular iron level and LPO, improve the expression of ferroptosis-protective proteins, and subsequently alleviate SAH-induced cell death. Additionally, autophagy inhibition also attenuated SAH prognostic indicators, such as brain edema, blood-brain barrier permeability, and neurological deficits. These findings not only present an opinion that SAH triggers neuronal ferroptosis via activation of ferritinophagy but also indicate that regulating ferritinophagy and maintaining ironhomeostasis could provide clues for the prevention of early brain injury.

What is the restorative effect of VEGF inhibitor bevacuzimab against subarachnoid hemorrhage in an experimental model?

This study investigated the effect of vascular endothelial growth factor (VEGF) inhibitor bevacuzimab (BVZ) on the rabbit basilar artery using an experimental subarachnoid hemorrhage (SAH) model. Eighteen adult male New-Zealand white rabbits were randomly divided into three groups: a control group (n = 6), SAH group (n = 6), and SAH+BVZ group (n = 6). Experimental SAH was created by injecting autologous arterial blood into the cisterna magna. In the treatment group, the subjects were administered a daily dose of 10 mg/kg, intravenous BVZ for 2 days after the SAH. Basilar artery diameters were measured with magnetic resonance angiography (MRA) 72 h after the SAH in all groups. After 72 h, whole brains, including the upper cervical region, were obtained from all the animals after perfusion and fixation of the animal. The wall thickness, luminal area, and the apoptosis at the basilar arteries were evaluated in all groups. BVZ significantly prevented SAH-induced vasospasm confirmed in vivo with MRA imaging with additional suppression of apoptosis on basilar artery wall. VEGF inhibition with BVZ has shown to have a vasospasm and apoptosis attenuating effect on basilar artery in a SAH model.

Pre-Chiasmatic, Single Injection of Autologous Blood to Induce Experimental Subarachnoid Hemorrhage in a Rat Model.

Despite advances in treatment over the last decades, subarachnoid hemorrhage (SAH) continues to carry a high burden of morbidity and mortality, largely afflicting a fairly young population. Several animal models of SAH have been developed to investigate the pathophysiological mechanisms behind SAH and to test pharmacological interventions. The pre-chiasmatic, single injection model in the rat presented in this article is an experimental model of SAH with a predetermined blood volume. Briefly, the animal is anesthetized, intubated, and kept under mechanical ventilation. Temperature is regulated with a heating pad. A catheter is placed in the tail artery, enabling continuous blood pressure measurement as well as blood sampling. The atlantooccipital membrane is incised and a catheter for pressure recording is placed in the cisterna magna to enable intracerebral pressure measurement. This catheter can also be used for intrathecal therapeutic interventions. The rat is placed in a stereotaxic frame, a burr hole is drilled anteriorly to the bregma, and a catheter is inserted through the burr hole and placed just anterior to the optic chiasm. Autologous blood (0.3 mL) is withdrawn from the tail catheter and manually injected. This results in a rise of intracerebral pressure and a decrease of cerebral blood flow. The animal is kept sedated for 30 min and given subcutaneous saline and analgesics. The animal is extubated and returned to its cage. The pre-chiasmatic model has a high reproducibility rate and limited variation between animals due to the pre-determined blood volume. It mimics SAH in humans making it a relevant model for SAH research.

Blockade of Motor Cortical Long-Term Potentiation Induction by Glutamatergic Dysfunction Causes Abnormal Neurobehavior in an Experimental Subarachnoid Hemorrhage Model.

Subarachnoid hemorrhage (SAH) is a life-threatening condition that can also lead to permanent paralysis. However, the mechanisms that underlying neurobehavioral deficits after SAH have not been fully elucidated. As theta burst stimulation (TBS) can induce long-term potentiation (LTP) in the motor cortex, we tested its potential as a functional evaluation tool after experimentally induced SAH. Motor cortical inter-neuronal excitability was evaluated in anesthetized rats after 200 Hz-quadripulse TBS (QTS5), 200 Hz-quadripulse stimulation (QPS5), and 400 Hz-octapulse stimulation (OPS2.5). Furthermore, correlation between motor cortical LTP and N-methyl-D-aspartate-receptor activation was evaluated using MK-801, a NMDA-receptor antagonist. We evaluated inhibition-facilitation configurations [interstimulus interval: 3 ms; short-latency intracortical inhibition (SICI) and 11 ms; intracortical facilitation (ICF)] with paired electrical stimulation protocols and the effect of TBS paradigm on continuous recording of motor-evoked potentials (MEPs) for quantitative parameters. SAH and MK-801 completely blocked ICF, while SICI was preserved. QTS5, QPS5, and OPS2.5 facilitated continuous MEPs, persisting for 180 min. Both SAH and MK-801 completely blocked MEP facilitations after QPS5 and OPS2.5, while MEP facilitations after QTS5 were preserved. Significant correlations were found among neurological scores and 3 ms-SICI rates, 11 ms-ICF rates, and MEP facilitation rates after 200 Hz-QTS5, 7 days after SAH (R2 = 0.6236; r = −0.79, R2 = 0.6053; r = −0.77 and R2 = 0.9071; r = 0.95, p < 0.05, respectively). Although these findings need to be verified in humans, our study demonstrates that the neurophysiological parameters 3 ms-SICI, 11 ms-ICF, and 200 Hz-QTS5-MEPs may be useful surrogate quantitative biomarkers for assessing inter-neuronal function after SAH.

Vitamin D-A New Perspective in Treatment of Cerebral Vasospasm.

BACKGROUNDCerebral vasospasm (CVS) is a frequent complication after subarachnoid hemorrhage (SAH), with no sufficient therapy and a complex pathophysiology.OBJECTIVETo explore the vitamin D system as a potential treatment for CVS.METHODS25-vitamin D3 levels tested between 2007 and 2015 and data of SAH patients admitted during the months with a peak vs nadir of VitD3 values were analyzed, retrospectively. We prospectively correlated VitD3 and vasospasm/outcome data in SAH patients admitted in 2017. An experimental mice SAH model and cell culture model were used to investigate the effect of 1,25-dihydroxyvitamin D3 (1,25-VitD3). Additionally, the mediators acting in the VitD mechanism were researched and detected.RESULTSBased on the retrospective analysis demonstrating an increased frequency of vasospasm in SAH patients during the low vitamin D period in winter, we started basic research experiments. Active 1,25-VitD3 hormone attenuated CVS, neurological deficit, and inflammation after intrathecal blood injection in mice. Deletion of the vitamin D receptor in the endothelium or in myeloid cells decreased the protective 1,25-VitD3 effect. Co-culture experiments of myeloid and endothelial cells with blood confirmed the anti-inflammatory 1,25-VitD3 effect but also revealed an induction of stroma-cell-derived factor 1α (SDF1α), vascular endothelial growth factor, and endothelial nitric oxide synthase by 1,25-VitD3. In mice, SDF1α mimicked the protective effect of 1,25-VitD3 against CVS. From bench to bedside, CVS severity was inversely correlated with vitamin D plasma level, prospectively. Patients with more severe CVS exhibited attenuated expression of SDF1α and 1,25-VitD3-responsive genes on circulating myeloid cells.CONCLUSION1,25-VitD3 attenuates CVS after SAH by inducing SDF1α. However, VitD administration should be tested as optional treatment to prevent CVS.

Sleep deprivation aggravates brain injury after experimental subarachnoid hemorrhage via TLR4-MyD88 pathway.

Subarachnoid hemorrhage (SAH) is a life-threatening cerebrovascular disease, and most of the SAH patients experience sleep deprivation during their hospital stay. It is well-known that sleep deprivation is one of the key components of developing several neurological disorders, but its effect on brain damage after SAH has not been determined. Therefore, this study was designed to evaluate the effect of sleep deprivation using an experimental SAH model in rats. Induction of sleep deprivation for 24 h aggravated the SAH-induced brain damage, as evidenced by brain edema, neuronal apoptosis and activation of caspase-3. Sleep deprivation also worsened the neurological impairment and cognitive deficits after SAH. The results of immunostaining and western blot showed that sleep deprivation increased the activation of microglial cells. In addition, sleep deprivation differently regulated the expression of anti-inflammatory and pro-inflammatory cytokines. The results of immunofluorescence staining and western blot showed that sleep deprivation markedly increased the activation of Toll-like receptor 4 (TLR4) and myeloid differentiation primary response protein 88 (MyD88). Mechanically, treatment with the TLR4 inhibitor TAK-242 or the MyD88 inhibitor ST2825 significantly attenuated the brain damage and neuroinflammation induced by sleep deprivation after SAH. In conclusion, our results indicate that sleep deprivation aggravates brain damage and neurological dysfunction following experimental SAH in rats. These effects were mediated by the activation of the TLR4-MyD88 cascades and regulation of neuroinflammation.