NMDA receptor antagonist felbamate reduces behavioral deficits and blood-brain barrier permeability changes after experimental subarachnoid hemorrhage in the rat

The Cell Permeant Phosphopetpide mimetic of VASP Alleviates Motor Function Deficits After Experimental Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) due to the rupture of an intracranial aneurysm leads to delayed vasospasm and neuroischemia, which can result in profound neurologic deficit and death. Therapeutic options after SAH are currently limited to hemodynamic optimization and nimodipine, which have limited clinical efficacy. Experimental SAH results in cerebral vasospasm have demonstrated the downregulation of nitric oxide (NO)-protein kinase G (PKG) signaling elements. VP3 is a novel cell permeant phosphopeptide mimetic of VASP, a substrate of PKG and an actin-associated protein that modulates vasorelaxation in vascular smooth muscle cells. In this study, we determined that intravenous administration of high doses of VP3 did not induce systemic hypotension in rats except at the maximal soluble dose, implying that VP3 is well-tolerated and has a wide therapeutic window. Using a single cisterna magna injection rat model of SAH, we demonstrated that intravenous administration of low-dose VP3 after SAH improved neurologic deficits for up to 14 days as determined by the rotarod test. These findings suggest that strategies aimed at targeting the cerebral vasculature with VP3 may improve neurologic deficits associated with SAH.

Memantine Attenuates Cognitive and Emotional Dysfunction in Mice with Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is the most common complication of sepsis, with increased morbidity and mortality. To date, there has still been no established pharmacological therapy. Memantine, as an NMDA (N-methyl-d-aspartate) receptor antagonist, exhibited neuroprotective effects against cognitive and emotional dysfunction in many disorders. We performed cecal ligation and puncture (CLP) inducing sepsis as the ideal animal model of SAE. CLP-induced septic mice were given a memantine treatment through intragastric administration. The novel object recognition test indicated that memantine significantly improved cognitive dysfunction in septic mice. The open field test revealed that the anxiety-like behaviors and locomotion ability of septic mice were relieved by memantine. The pole test further confirmed the protective effects of memantine against immobility. Memantine significantly inhibited the excessive glutamate production and improved impaired neurogenesis on first and seventh day after sepsis, accompanying with reducing proinflammatory cytokines production (tumor necrosis factor alpha (TNF-α), interleukin (IL)-1beta (IL-1β), and IL-10) and microglia activation in the brain of SAE. In addition, memantine treatment also reducing sepsis-induced brain blood barrier disruption via inhibiting the expression of metalloproteinase-9 (MMP-9). In conclusion, memantine exerted neuro-protective effects against cognitive and emotional defects, which might be considered as a promising therapy for SAE.

TREM2 modulates neuroinflammation with elevated IRAK3 expression and plays a neuroprotective role after experimental SAH in rats

BACKGROUND

The modulation of neuroinflammation is a new direction that may alleviate the early brain injury after subarachnoid hemorrhage (SAH). Brain resident microglia/macrophages (Mi/MΦ) are the key drivers of neuroinflammation. Triggering receptor expressed on myeloid cells 2 (TREM2) has been reported to play a neuroprotective role by activating phagocytosis and suspending inflammatory response in experimental ischemic stroke and intracerebral hemorrhage. This study was designed to investigate the role of TREM2 on neuroinflammation and neuroprotective effects in a rat SAH model.

METHODS

Adult male Sprague-Dawley rats were induced SAH through endovascular perforation. Lentivirus vectors were administered by i.c.v. to induce TREM2 overexpression or knockdown 7 days before SAH induction. Short- and long-term neurobehavioral tests, western blotting, immunofluorescence, enzyme-linked immunosorbent assay, terminal deoxynucleotidyl transferase dUTP nick end labeling and Nissl staining were performed to explore the neuroprotective role of TREM2 after SAH.

RESULTS

The expression of TREM2 elevated in a rat SAH model with a peak at 48 h after SAH and mainly expressed in Mi/MΦ in brain. TREM2 overexpression improved short- and long-term neurological deficits induced by SAH in rats, while TREM2 knockdown worsened neurological dysfunction. The rats with TREM2 overexpressed presented less neuronal apoptosis and more neuronal survival at 48 h after SAH, while the rats with TREM2 knockdown presented on the contrary. TREM2 overexpression manifested activated phagocytosis and suppressed inflammatory response, with the increase of CD206⁺/CD11b⁺ cells and IL-10 expression as well as the decrease of the infiltration of MPO⁺ cells and the expression of TNF-α, IL-1β. While TREM2 knockdown abolished these effects. The protein level of IRAK3, a negative regulatory factor of inflammation, was significantly elevated after TREM2 overexpression and declined after TREM2 knockdown.

CONCLUSIONS

Our research suggested TREM2 played a neuroprotective role and improved the short- and long-term neurological deficits by modulating neuroinflammation after SAH. The modulation on neuroinflammation of TREM2 after SAH was related with the elevated protein level of IRAK3.

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.

Calpain Inhibitors as Potential Therapeutic Modulators in Neurodegenerative Diseases

It is considered a significant challenge to understand the neuronal cell death mechanisms with a suitable cure for neurodegenerative disorders in the coming years. Calpains are one of the best-considered "cysteine proteases activated" in brain disorders. Calpain is an important marker and mediator in the pathophysiology of neurodegeneration. Calpain activation being the essential neurodegenerative factor causing apoptotic machinery activation, it is crucial to develop reliable and effective approaches to prevent calpain-mediated apoptosis in degenerating neurons. It has been recently seen that the "inhibition of calpain activation" has appeared as a possible therapeutic target for managing neurodegenerative diseases. A systematic literature review of PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was conducted. The present article reviews the basic pathobiology and role of selective calpain inhibitors used in various neurodegenerative diseases as a therapeutic target.

Association between vasoactive peptide urotensin II in plasma and cerebral vasospasm after aneurysmal subarachnoid hemorrhage: a potential therapeutic target

OBJECTIVE

Cerebral vasospasm (VS) is a severe complication of aneurysmal subarachnoid hemorrhage (SAH). Urotensin II (UII) is a potent vasoactive peptide activating the urotensin (UT) receptor, potentially involved in brain vascular pathologies. The authors hypothesized that UII/UT system antagonism with the UT receptor antagonist/biased ligand urantide may be associated with post-SAH VS. The objectives of this study were 2-fold: 1) to leverage an experimental mouse model of SAH with VS in order to study the effect of urotensinergic system antagonism on neurological outcome, and 2) to investigate the association between plasma UII level and symptomatic VS after SAH in human patients.

METHODS

A mouse model of SAH was used to study the impacts of UII and the UT receptor antagonist/biased ligand urantide on VS and neurological outcome. Then a clinical study was conducted in the setting of a neurosurgical intensive care unit. Plasma UII levels were measured in SAH patients daily for 9 days, starting on the 1st day of hospitalization, and were compared with plasma UII levels in healthy volunteers.

RESULTS

In the mouse model, urantide prevented VS as well as SAH-related fine motor coordination impairment. Seventeen patients with SAH and external ventricular drainage were included in the clinical study. The median plasma UII level was 43 pg/ml (IQR 14-80 pg/ml). There was no significant variation in the daily median plasma UII level (median value for the 17 patients) from day 0 to day 8. The median level of plasma UII during the 9 first days post-SAH was higher in patients with symptomatic VS than in patients without VS (77 pg/ml [IQR 33.5-111.5 pg/ml] vs 37 pg/ml [IQR 21-46 pg/ml], p < 0.05). Concerning daily measures of plasma UII levels in VS, non-VS patients, and healthy volunteers, we found a significant difference between SAH patients with VS (median 66 pg/ml [IQR 30-110 pg/ml]) and SAH patients without VS (27 pg/ml [IQR 15-46 pg/ml], p < 0.001) but no significant difference between VS patients and healthy volunteers (44 pg/ml [IQR 27-51 pg/ml]) or between non-VS patients and healthy volunteers.

CONCLUSIONS

The results of this study suggest that UT receptor antagonism with urantide prevents VS and improves neurological outcome after SAH in mice and that an increase in plasma UII is associated with cerebral VS subsequent to SAH in humans. The causality link between circulating UII and VS after SAH remains to be established, but according to our data the UT receptor is a potential therapeutic target in SAH.

Neuroprotective Effect of ZnT3 Knockout on Subarachnoid Hemorrhage

Background

The pathophysiology of early brain injury (EBI) after subarachnoid hemorrhage (SAH) is poorly understood. The present study evaluates the influence of zinc transporter 3 (ZnT3) knockout and the depletion of vesicular zinc on EBI.

Methodology

SAH was induced in ZnT3 KO mice by internal carotid artery perforation. The changes in behavior were recorded at 24 hours after SAH. Hematoxylin-eosin, Nissl and TUNEL staining were performed to evaluate neuronal apoptosis. Data from mice with a score of 8-12 in intracerebral bleeding (i.e. moderate SAH), were analyzed.

Results

The degree of SAH-induced neuronal injury was directly correlated to the amount of blood lost, which in turn was negatively reflected in their behavior. The Wild Type (WT)-SAH group behaved poorly when compared to the knockout (KO)-SAH mice and their poor neurological score was accompanied by an increase in the number of apoptotic neurons. Conversely, the improvement of behavior in the KO-SAH group was associated with a marked reduction in apoptotic neurons.

Conclusions

These results suggest that ZnT3 knockout may have played a vital role in the attenuation of neuronal injury after SAH and that ZnT3 may prove to be a potential therapeutic target for neuroprotection in EBI.

Unique Contribution of Haptoglobin and Haptoglobin Genotype in Aneurysmal Subarachnoid Hemorrhage

Survivors of cerebral aneurysm rupture are at risk for significant morbidity and neurological deficits. Much of this is related to the effects of blood in the subarachnoid space which induces an inflammatory cascade with numerous downstream consequences. Recent clinical trials have not been able to reduce the toxic effects of free hemoglobin or improve clinical outcome. One reason for this may be the inability to identify patients at high risk for neurologic decline. Recently, haptoglobin genotype has been identified as a pertinent factor in diabetes, sickle cell, and cardiovascular disease, with the Hp 2-2 genotype contributing to increased complications. Haptoglobin is a protein synthesized by the liver that binds free hemoglobin following red blood cell lysis, and in doing so, prevents hemoglobin induced toxicity and facilitates clearance. Clinical studies in patients with subarachnoid hemorrhage indicate that Hp 2-2 patients may be a high-risk group for hemorrhage related complications and poor outcome. We review the relevance of haptoglobin in subarachnoid hemorrhage and discuss the effects of genotype and expression levels on the known mechanisms of early brain injury (EBI) and cerebral ischemia after aneurysm rupture. A better understanding of haptoglobin and its role in preventing hemoglobin related toxicity should lead to novel therapeutic avenues.

Hypoxia-Preconditioned Human Umbilical Vein Endothelial Cells Protect Against Neurovascular Damage After Hypoxic Ischemia in Neonatal Brain

Therapy targeting the neurovascular unit may provide effective neuroprotection against neonatal hypoxia-ischemia (HI). We hypothesized that the peripheral injection of hypoxia-preconditioned human umbilical vein endothelial cells (HUVECs) following HI protects against neurovascular damage and provides long-term neuroprotection in a postpartum (P) day-7 rat pup model. Compared with normoxic HUVECs, hypoxic HUVECs showed enhanced migration and angiogenesis in vitro and had augmented migration effects into the brain when administered intraperitoneally in vivo after HI. Moreover, 24 and 72 h post-HI, the hypoxic HUVECs group but not the normoxic HUVECs or culture-medium groups had significantly higher preservation of microvessels and neurons, and attenuation of blood-brain barrier damage than the normal-saline group. Compared to control or normal-saline groups, only the hypoxic HUVECs group had no impaired foot steps and showed a significant reduction of brain area loss at P42. Next-generation sequencing showed hypoxia-induced upregulation and downregulation of 209 and 215 genes in HUVECs, respectively. Upstream regulator analysis by ingenuity pathway analysis (IPA) identified hypoxia-inducible factor 1-alpha as the key predicted activated transcription regulator. After hypoxia, 12 genes (ADAMTS1, EFNA1, HIF1A, LOX, MEOX2, SELE, VEGFA, VEGFC, CX3CL1, HMMR, SDC, and SERPINE) associated with migration and/or angiogenesis were regulated in HUVECs. In addition, 6 genes (VEGFA, VEGFC, NTN4, TGFA, SERPINE1, and CX3CL1) involved in the survival of endothelial and neuronal cells were also markedly altered in hypoxic HUVECs. Thus, cell therapy by using hypoxic HUVECs that enhance migration and neurovascular protection may provide an effective therapeutic strategy for treating neonatal asphyxia.

Potential implications of Apolipoprotein E in early brain injury after experimental subarachnoid hemorrhage: Involvement in the modulation of blood-brain barrier integrity

Apolipoprotein E (Apoe) genetic polymorphisms have been implicated in the long term outcome of subarachnoid haemorrhage (SAH), but little is known about the effect of Apoe on the early brain injury (EBI) after SAH. This study investigated the potential role of APOE in EBI post-SAH. Multiple techniques were used to determine the early BBB disruption in EBI post-SAH in a murine model using wild-type (WT) and Apoe^−/− (KO) mice. Progressive BBB disruption (Evans blue extravasation and T2 hyperintensity in magnetic resonance imaging) was observed before the peak of endogenous APOE expression elevation at 48h after SAH. Moreover, Apoe^−/− mice exhibited more severe BBB disruption charcteristics after SAH than WT mice, including higher levels of Evans blue and IgG extravasation, T2 hyperintensity in magnetic resonance imaging, tight junction proteins degradation and endothelial cells death. Mechanistically, we found that APOE restores the BBB integrity in the acute stage after SAH via the cyclophilin A (CypA)-NF-κB-proinflammatory cytokines-MMP-9 signalling pathway. Consequently, although early BBB disruption causes neurological dysfunctions after SAH, we capture a different aspect of the effects of APOE on EBI after SAH that previous studies had overlooked and open up the idea of BBB disruption as a target of APOE-based therapy for EBI amelioration research in the future.

Neurobehavioral testing in subarachnoid hemorrhage: A review of methods and current findings in rodents

The most important aspect of a preclinical study seeking to develop a novel therapy for neurological diseases is whether the therapy produces any clinically relevant functional recovery. For this purpose, neurobehavioral tests are commonly used to evaluate the neuroprotective efficacy of treatments in a wide array of cerebrovascular diseases and neurotrauma. Their use, however, has been limited in experimental subarachnoid hemorrhage studies. After several randomized, double-blinded, controlled clinical trials repeatedly failed to produce a benefit in functional outcome despite some improvement in angiographic vasospasm, more rigorous methods of neurobehavioral testing became critical to provide a more comprehensive evaluation of the functional efficacy of proposed treatments. While several subarachnoid hemorrhage studies have incorporated an array of neurobehavioral assays, a standardized methodology has not been agreed upon. Here, we review neurobehavioral tests for rodents and their potential application to subarachnoid hemorrhage studies. Developing a standardized neurobehavioral testing regimen in rodent studies of subarachnoid hemorrhage would allow for better comparison of results between laboratories and a better prediction of what interventions would produce functional benefits in humans.

ErbB4 protects against neuronal apoptosis via activation of YAP/PIK3CB signaling pathway in a rat model of subarachnoid hemorrhage

Neuronal apoptosis is a central pathological process in subarachnoid hemorrhage (SAH)-induced early brain injury. Previous studies indicated that ErbB4 (EGFR family member v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 4) is essential for normal development and maintenance of the nervous system. In this study, we explored the neuroprotective effects of ErbB4 and its downstream YAP (yes-associated protein)/PIK3CB signaling pathway in early brain injury after SAH in a rat model using the endovascular perforation method. Rats were neurologically evaluated with the Modified Garcia Scale and beam balance test at 24h and 72h after SAH. An ErbB4 activator Neuregulin 1β1 (Nrg 1β1), ErbB4 siRNA and YAP siRNA were used to explore this pathway. The expression of p-ErbB4 and YAP was significantly increased after SAH. Multiple immunofluorescence labeling experiments demonstrated that ErbB4 is mainly expressed in neurons. Activation of ErbB4 and its downstream signals improved the neurological deficits after SAH and significantly reduced neuronal cell death. Inhibition of ErbB4 reduced YAP and PIK3CB expression, and aggravated cell apoptosis. YAP knockdown reduced the PIK3CB level and eliminated the anti-apoptotic effects of ErbB4 activation. These findings indicated that ErbB4 plays a neuroprotective role in early brain injury after SAH, possibly via the YAP/PIK3CB signaling pathway.

Biodegradable seeds of holmium don't change neurological function after implant in brain of rats

AIM

To evaluate the surgical procedure and parenchymal abnormalities related to implantation of ceramic seeds with holmium-165 in rats' brain.

BACKGROUND

An effective method of cancer treatment is brachytherapy in which radioactive seeds are implanted in the tumor, generating a high local dose of ionizing radiation that can eliminate tumor cells while protecting the surrounding healthy tissue. Biodegradable Ho¹⁶⁶-ceramic-seeds have been addressed recently.

METHODS AND MATERIALS

The experiments in this study were approved by the Ethics Committee on Animal Use at the Federal University of Ouro Preto, protocol number 2012/034. Twenty-one adult Fischer rats were divided into Naive Group, Sham Group and Group for seed implants (ISH). Surgical procedures for implantation of biodegradable seeds were done and 30 days after the implant radiographic examination and biopsy of the brain were performed. Neurological assays were also accomplished to exclude any injury resulting from either surgery or implantation of the seeds.

RESULTS

Radiographic examination confirmed the location of the seeds in the brain. Neurological assays showed animals with regular spontaneous activity. The histological analysis showed an increase of inflammatory cells in the brain of the ISH group. Electron microscopy evidenced cytoplasmic organelles to be unchanged. Biochemical analyzes indicate there was neither oxidative stress nor oxidative damage in the ISH brain. CAT activity showed no difference between the groups as well as lipid peroxidation measured by TBARS.

CONCLUSIONS

The analysis of the data pointed out that the performed procedure is safe as no animal showed alterations of the neurological parameters and the seeds did not promote histological architectural changes in the brain tissue.

Long-Lasting Cerebral Vasospasm, Microthrombosis, Apoptosis and Paravascular Alterations Associated with Neurological Deficits in a Mouse Model of Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating disease with high mortality and morbidity. Long-term cognitive and sensorimotor deficits are serious complications following SAH but still not well explained and described in mouse preclinical models. The aim of our study is to characterize a well-mastered SAH murine model and to establish developing pathological mechanisms leading to cognitive and motor deficits, allowing identification of specific targets involved in these long-term troubles. We hereby demonstrate that the double blood injection model of SAH induced long-lasting large cerebral artery vasospasm (CVS), microthrombosis formation and cerebral brain damage including defect in potential paravascular diffusion. These neurobiological alterations appear to be associated with sensorimotor and cognitive dysfunctions mainly detected 10 days after the bleeding episode. In conclusion, this characterized model of SAH in mice, stressing prolonged neurobiological pathological mechanisms and associated sensitivomotor deficits, will constitute a validated preclinical model to better decipher the link between CVS, long-term cerebral apoptosis and cognitive disorders occurring during SAH and to allow investigating novel therapeutic approaches in transgenic mice.

Seizures and Epileptiform Patterns in SAH and Their Relation to Outcomes

In subarachnoid hemorrhage (SAH), seizures are frequent and occur at different time points, likely reflecting heterogeneous pathophysiology. Young patients, those with more severe SAH (by clot burden or presence of severe mental status changes at onset or focal neurologic deficits at any time), those with associated increased cortical irritation (by infarction or presence of underlying hematoma), and patients undergoing craniotomy are at higher risk. Advanced neurophysiologic monitoring allows for seizure burden quantification, identification of subclinical seizures, and interictal patterns as well as neurovascular complications that may have an independent impact on the outcome in this population. Practice regarding seizure prophylaxis varies widely; its institution is often guided by the risk-benefit ratio of seizures and medication side effects. Newer anticonvulsants seem to be equally effective and may have a more favorable profile. However, questions regarding the association of seizures and vasospasm, the therapeutic dosing, timing, and duration of antiepileptic treatment and the impact of seizures and antiepileptics on the outcome remain unanswered. In this review, we provide a broad overview of the work in this area and offer a diagnostic and therapeutic approach based on our own expert opinion.

Inhibition of Blood-Brain Barrier Disruption by an Apolipoprotein E-Mimetic Peptide Ameliorates Early Brain Injury in Experimental Subarachnoid Hemorrhage

Apolipoprotein E (ApoE)-mimetic peptides have been demonstrated to be beneficial in secondary brain injury following experimental subarachnoid hemorrhage (SAH). However, the molecular mechanisms underlying these benefits in SAH models have not been clearly identified. This study investigated whether an ApoE-mimetic peptide affords neuroprotection in early brain injury (EBI) following SAH by attenuating BBB disruption. SAH was induced by an endovascular perforation in young, healthy, male wild-type (WT) C57BL/6J mice. Multiple techniques, including MRI with T2-weighted imaging, ¹⁸ FDG PET-CT scanning and histological studies, were used to examine BBB integrity and neurological dysfunction in EBI following SAH. We found that SAH induced a significant increase of BBB permeability and neuron apoptosis, whereas ApoE-mimetic peptide treatment significantly reduced the degradation of tight junction proteins and endothelial cell apoptosis. These effects reduced brain edema and neuron apoptosis, increased cerebral glucose uptake, and improved neurological functions. Further investigation revealed that the ApoE-mimetic peptide inhibited the proinflammatory activators of MMP-9, including CypA, NF-κB, IL-6, TNF-α, and IL-1β, thereby ameliorating BBB disruption at the acute stage of SAH. Together, these data indicate that ApoE-mimetic peptide may be a novel and promising therapeutic strategy for EBI amelioration after SAH that are worthy of further study.

Neutrophil depletion after subarachnoid hemorrhage improves memory via NMDA receptors

Cognitive deficits after aneurysmal subarachnoid hemorrhage (SAH) are common and disabling. Patients who experience delayed deterioration associated with vasospasm are likely to have cognitive deficits, particularly problems with executive function, verbal and spatial memory. Here, we report neurophysiological and pathological mechanisms underlying behavioral deficits in a murine model of SAH. On tests of spatial memory, animals with SAH performed worse than sham animals in the first week and one month after SAH suggesting a prolonged injury. Between three and six days after experimental hemorrhage, mice demonstrated loss of late long-term potentiation (L-LTP) due to dysfunction of the NMDA receptor. Suppression of innate immune cell activation prevents delayed vasospasm after murine SAH. We therefore explored the role of neutrophil-mediated innate inflammation on memory deficits after SAH. Depletion of neutrophils three days after SAH mitigates tissue inflammation, reverses cerebral vasoconstriction in the middle cerebral artery, and rescues L-LTP dysfunction at day 6. Spatial memory deficits in both the short and long-term are improved and associated with a shift of NMDA receptor subunit composition toward a memory sparing phenotype. This work supports further investigating suppression of innate immunity after SAH as a target for preventative therapies in SAH.

Aneurysmal Subarachnoid Hemorrhage and Neuroinflammation: A Comprehensive Review

Aneurysmal subarachnoid hemorrhage (SAH) can lead to devastating outcomes including vasospasm, cognitive decline, and even death. Currently, treatment options are limited for this potentially life threatening injury. Recent evidence suggests that neuroinflammation plays a critical role in injury expansion and brain damage. Red blood cell breakdown products can lead to the release of inflammatory cytokines that trigger vasospasm and tissue injury. Preclinical models have been used successfully to improve understanding about neuroinflammation following aneurysmal rupture. The focus of this review is to provide an overview of how neuroinflammation relates to secondary outcomes such as vasospasm after aneurysmal rupture and to critically discuss pharmaceutical agents that warrant further investigation for the treatment of subarachnoid hemorrhage. We provide a concise overview of the neuroinflammatory pathways that are upregulated following aneurysmal rupture and how these pathways correlate to long-term outcomes. Treatment of aneurysm rupture is limited and few pharmaceutical drugs are available. Through improved understanding of biochemical mechanisms of injury, novel treatment solutions are being developed that target neuroinflammation. In the final sections of this review, we highlight a few of these novel treatment approaches and emphasize why targeting neuroinflammation following aneurysmal subarachnoid hemorrhage may improve patient care. We encourage ongoing research into the pathophysiology of aneurysmal subarachnoid hemorrhage, especially in regards to neuroinflammatory cascades and the translation to randomized clinical trials.

Molecular, Cellular and Clinical Aspects of Intracerebral Hemorrhage: Are the Enemies Within?

Hemorrhagic stroke is a disease with high incidence and mortality rates. In addition to the mass lesions that result from hemorrhagic stroke, substances such as the blood-derived products (BDP) (hemoglobin (Hb), heme and iron) induce a potent inflammatory response and exert direct toxic effects on neurons, astrocytes, and microglia. In the present review, we discuss the mechanisms of brain injury secondary to hemorrhagic stroke, focusing on the involvement of BDP as major players of cellular redox imbalance, inflammation, and glutamate excitotoxicity. Potential natural mechanisms of protection against free Hb and heme such as haptoglobin and hemopexin, respectively, are highlighted. We finally discuss the experimental and clinical trials targeting free iron and heme scavenging as well as inflammation, as potential new therapies to minimize the devastating effects of hemorrhagic stroke on brain structure and function.

A Study on Neuroprotective Effects of Curcumin on the Diabetic Rat Brain

The present study was aimed to study the neuroprotective therapeutic effect of curcumin on the male albino rat brain. Subarachnoid hemorrhage leads to severe mortality rate and morbidity, and oxidative stress is a crucial factor in subarachnoid hemorrhage. Therefore, we investigated the effect of curcumin on oxidative stress and glutamate and glutamate transporter-1 on a subarachnoid hemorrhage-induced male albino rats. The curcumin commonly used for the treatment and saline used for the control. Curcumin (10 mg/kg bwt) dissolved in saline and administered orally to the rats for one week. Glutamate, glutamate transporter-1, malondialdehyde (MDA), superoxide dismutase (SOD), catalase, glutathione reductase and lactate dehydrogenase (LDH) activities were determined. Glutamate level was lower in the curcumin-treated rats compared to their respective controls. Glutamate transporter-1 did not alter in the curcumin-treated rats compared to their controls. Glutamate transporter-1 protein expression is significantly reduced in the curcumin-treated rats. MDA levels decreased 18 and 29 % in the hippocampus and the cortex region respectively. SOD (17% and 32%), and catalase (19% and 24%) activities were increased in the curcumin-treated hippocampus and the cortex region respectively. Glutathione reductase (13% and 19%) and LDH (21% and 30%) activities were increased in the treated hippocampus and the cortex region respectively. The mRNA expression of NK-kB and TLR4 was significantly reduced following curcumin treatment. Taking all these data together, the curcumin found to be effective against oxidative stress and glutamate neurotoxicity in the male albino rats.

Memantine Attenuates Delayed Vasospasm after Experimental Subarachnoid Hemorrhage via Modulating Endothelial Nitric Oxide Synthase

Delayed cerebral vasospasm is an important pathological feature of subarachnoid hemorrhage (SAH). The cause of vasospasm is multifactorial. Impairs nitric oxide availability and endothelial nitric oxide synthase (eNOS) dysfunction has been reported to underlie vasospasm. Memantine, a low-affinity uncompetitive N-methyl-d-aspartate (NMDA) blocker has been proven to reduce early brain injury after SAH. This study investigated the effect of memantine on attenuation of vasospasm and restoring eNOS functionality. Male Sprague-Dawley rats weighing 350–450 g were randomly divided into three weight-matched groups, sham surgery, SAH + vehicle, and SAH + memantine groups. The effects of memantine on SAH were evaluated by assessing the severity of vasospasm and the expression of eNOS. Memantine effectively ameliorated cerebral vasospasm by restoring eNOS functionality. Memantine can prevent vasospasm in experimental SAH. Treatment strategies may help combat SAH-induced vasospasm in the future.

Rosiglitazone attenuates cerebral vasospasm and provides neuroprotection in an experimental rat model of subarachnoid hemorrhage

BACKGROUND

Glutamate and oxidative stress play important roles after subarachnoid hemorrhage (SAH). The ability to modulate glutamate transporter 1 (GLT-1) and the antioxidative effect of rosiglitazone have been demonstrated. We investigated the neuroprotective effect of rosiglitazone after SAH.

METHODS

SAH was induced by double blood injection. The rats were randomly divided into sham, SAH + vehicle, and SAH + rosiglitazone groups and treated with dimethyl sulfoxide, dimethyl sulfoxide, and 6 mg/kg of rosiglitazone, respectively, at 2 and 12 h after SAH induction and then daily for 6 days. Cerebrospinal fluid dialysates were collected 30 min before SAH induction and then daily for 7 days for glutamate measurement. Mortality, body weight, and neurological scores were also measured daily. On day 7 after SAH, the wall thickness and the perimeter of the basilar artery (BA), neuron variability, GLT-1 levels, glial fibrillary acidic protein (GFAP) expression and activity, and malondialdehyde, superoxide dismutase, and catalase activities were also evaluated.

RESULTS

Rosiglitazone improved survival (relative risk = 0.325) and neurological functions and reduced neuronal degeneration (5.7 ± 0.8 vs. 10.0 ± 0.9; P < 0.001) compared with the SAH + vehicle group. Rosiglitazone also lowered glutamate levels by 43.5-fold and upregulated GLT-1 expression by 1.5-fold and astrocyte activity by 1.8-fold compared with the SAH + vehicle group. The increase in BA wall thickness was significantly attenuated by rosiglitazone, whereas the perimeter of the BA was increased. In addition, rosiglitazone abated the 1.9-fold increase in malondialdehyde levels and the 1.6-fold increase in catalase activity after SAH.

CONCLUSION

Rosiglitazone reduced SAH mortality, neurological deficits, body weight loss, GFAP loss, and cerebral vasospasm by preventing the neurotoxicity induced by glutamate and oxidative stress.

Astrocytic TYMP and VEGFA drive blood-brain barrier opening in inflammatory central nervous system lesions

In inflammatory central nervous system conditions such as multiple sclerosis, breakdown of the blood-brain barrier is a key event in lesion pathogenesis, predisposing to oedema, excitotoxicity, and ingress of plasma proteins and inflammatory cells. Recently, we showed that reactive astrocytes drive blood-brain barrier opening, via production of vascular endothelial growth factor A (VEGFA). Here, we now identify thymidine phosphorylase (TYMP; previously known as endothelial cell growth factor 1, ECGF1) as a second key astrocyte-derived permeability factor, which interacts with VEGFA to induce blood-brain barrier disruption. The two are co-induced NFκB1-dependently in human astrocytes by the cytokine interleukin 1 beta (IL1B), and inactivation of Vegfa in vivo potentiates TYMP induction. In human central nervous system microvascular endothelial cells, VEGFA and the TYMP product 2-deoxy-d-ribose cooperatively repress tight junction proteins, driving permeability. Notably, this response represents part of a wider pattern of endothelial plasticity: 2-deoxy-d-ribose and VEGFA produce transcriptional programs encompassing angiogenic and permeability genes, and together regulate a third unique cohort. Functionally, each promotes proliferation and viability, and they cooperatively drive motility and angiogenesis. Importantly, introduction of either into mouse cortex promotes blood-brain barrier breakdown, and together they induce severe barrier disruption. In the multiple sclerosis model experimental autoimmune encephalitis, TYMP and VEGFA co-localize to reactive astrocytes, and correlate with blood-brain barrier permeability. Critically, blockade of either reduces neurologic deficit, blood-brain barrier disruption and pathology, and inhibiting both in combination enhances tissue preservation. Suggesting importance in human disease, TYMP and VEGFA both localize to reactive astrocytes in multiple sclerosis lesion samples. Collectively, these data identify TYMP as an astrocyte-derived permeability factor, and suggest TYMP and VEGFA together promote blood-brain barrier breakdown.

Early brain injury, an evolving frontier in subarachnoid hemorrhage research

Subarachnoid hemorrhage (SAH), predominantly caused by a ruptured aneurysm, is a devastating neurological disease that has a morbidity and mortality rate higher than 50%. Most of the traditional in vivo research has focused on the pathophysiological or morphological changes of large-arteries after intracisternal blood injection. This was due to a widely held assumption that delayed vasospasm following SAH was the major cause of delayed cerebral ischemia and poor outcome. However, the results of the CONSCIOUS-1 trial implicated some other pathophysiological factors, independent of angiographic vasospasm, in contributing to the poor clinical outcome. The term early brain injury (EBI) has been coined and describes the immediate injury to the brain after SAH, before onset of delayed vasospasm. During the EBI period, a ruptured aneurysm brings on many physiological derangements such as increasing intracranial pressure (ICP), decreased cerebral blood flow (CBF), and global cerebral ischemia. These events initiate secondary injuries such as blood-brain barrier disruption, inflammation, and oxidative cascades that all ultimately lead to cell death. Given the fact that the reversal of vasospasm does not appear to improve patient outcome, it could be argued that the treatment of EBI may successfully attenuate some of the devastating secondary injuries and improve the outcome of patients with SAH. In this review, we provide an overview of the major advances in EBI after SAH research.

Memantine alleviates brain injury and neurobehavioral deficits after experimental subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) causes brain injury via glutamate excitotoxicity, which leads to an excessive Ca(2+) influx and this starts an apoptotic cascade. Memantine has been proven to reduce brain injury in several types of brain insults. This study investigated the neuro-protective potential of memantine after SAH and explored the underlying mechanisms. An endovascular perforation rat model of SAH was used and Sprague-Dawley rats were randomized into sham surgery, SAH + vehicle, and SAH + memantine groups. The effects of memantine on SAH were evaluated by assessing the neuro-behavioral functions, blood-brain barrier (BBB) permeability and neuronal cell preservation. The mechanisms of action of memantine, with its N-methyl-D-aspartate (NMDA) antagonistic characteristics on nitric oxide synthase (NOS) expression and peroxynitrite formation, were also investigated. The apoptotic cascade after SAH was suppressed by memantine. Neuronal NOS (nNOS) expression, peroxynitrite formation, and subsequent oxidative/nitrosative stress were also reduced. Memantine effectively preserved BBB integrity, rescued neuronal injury, and improved neurological outcome in experimental SAH. Memantine has neuro-protective potential in experimental SAH and may help combat SAH-induced brain damage in the future.

To look beyond vasospasm in aneurysmal subarachnoid haemorrhage

Delayed cerebral vasospasm has classically been considered the most important and treatable cause of mortality and morbidity in patients with aneurysmal subarachnoid hemorrhage (aSAH). Secondary ischemia (or delayed ischemic neurological deficit, DIND) has been shown to be the leading determinant of poor clinical outcome in patients with aSAH surviving the early phase and cerebral vasospasm has been attributed to being primarily responsible. Recently, various clinical trials aimed at treating vasospasm have produced disappointing results. DIND seems to have a multifactorial etiology and vasospasm may simply represent one contributing factor and not the major determinant. Increasing evidence shows that a series of early secondary cerebral insults may occur following aneurysm rupture (the so-called early brain injury). This further aggravates the initial insult and actually determines the functional outcome. A better understanding of these mechanisms and their prevention in the very early phase is needed to improve the prognosis. The aim of this review is to summarize the existing literature on this topic and so to illustrate how the presence of cerebral vasospasm may not necessarily be a prerequisite for DIND development. The various factors determining DIND that worsen functional outcome and prognosis are then discussed.

Controversies and evolving new mechanisms in subarachnoid hemorrhage

Despite decades of study, subarachnoid hemorrhage (SAH) continues to be a serious and significant health problem in the United States and worldwide. The mechanisms contributing to brain injury after SAH remain unclear. Traditionally, most in vivo research has heavily emphasized the basic mechanisms of SAH over the pathophysiological or morphological changes of delayed cerebral vasospasm after SAH. Unfortunately, the results of clinical trials based on this premise have mostly been disappointing, implicating some other pathophysiological factors, independent of vasospasm, as contributors to poor clinical outcomes. Delayed cerebral vasospasm is no longer the only culprit. In this review, we summarize recent data from both experimental and clinical studies of SAH and discuss the vast array of physiological dysfunctions following SAH that ultimately lead to cell death. Based on the progress in neurobiological understanding of SAH, the terms "early brain injury" and "delayed brain injury" are used according to the temporal progression of SAH-induced brain injury. Additionally, a new concept of the vasculo-neuronal-glia triad model for SAH study is highlighted and presents the challenges and opportunities of this model for future SAH applications.

Iron chelation and multiple sclerosis

Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1α, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6-8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood-brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen.

ALS and oxidative stress: the neurovascular scenario

Oxidative stress and angiogenic factors have been placed as the prime focus of scientific investigations after an establishment of link between vascular endothelial growth factor promoter (VEGF), hypoxia, and amyotrophic lateral sclerosis (ALS) pathogenesis. Deletion of the hypoxia-response element in the vascular endothelial growth factor promoter and mutant superoxide dismutase 1 (SOD1) which are characterised by atrophy and muscle weakness resulted in phenotype resembling human ALS in mice. This results in lower motor neurodegeneration thus establishing an important link between motor neuron degeneration, vasculature, and angiogenic molecules. In this review, we have presented human, animal, and in vitro studies which suggest that molecules like VEGF have a therapeutic, diagnostic, and prognostic potential in ALS. Involvement of vascular growth factors and hypoxia response elements also highlights the converging role of oxidative stress and neurovascular network for understanding and treatment of various neurodegenerative disorders like ALS.

Perihematomal glutamate level is associated with the blood-brain barrier disruption in a rabbit model of intracerebral hemorrhage

Objective

To observe the relationship between the perihematomal glutamate levels and the blood–brain barrier (BBB) permeability in a rabbit model of intracerebral hemorrhage (ICH).

Methods

Seventy-two rabbits were randomly divided into an intracerebral hemorrhage (ICH) model group and a normal control (NC) group, and each group of 36 rabbits was subsequently divided into 6, 12, 18, 24, 48 and 72 h groups (n = 6 each). An ICH model was induced by stereotactic injection of autologous, arterial, non-anticoagulated blood into rabbit basal ganglia. The same procedures were performed in the NC group, but blood was not injected. The rabbits were sacrificed at specific time points after the experiment began depending on their group. Perihematomal brain tissues were collected to determine glutamate levels, BBB permeability and brain water content (BWC).

Results

All of the assessed parameters were increased 6 hour after blood infusion and continued to gradually increase, peaking at 48 hours. Differences were observed when ICH values were compared with those of the NC group (p < 0.05).

Conclusions

Perihematomal glutamate increased significantly after ICH. High levels of glutamate are closely associated with BBB disruption and the brain edema. Therefore, glutamate may play an important role in the pathogenesis of secondary brain injury after (ICH).

Attenuation of neurological injury with early baicalein treatment following subarachnoid hemorrhage in rats

OBJECT

Baicalein has been shown to offer neuroprotection in the ischemic brain, but its effect in subarachnoid hemorrhage (SAH) is unknown. The authors used a double-hemorrhage model to study the role of early baicalein treatment in SAH.

METHODS

Subarachnoid hemorrhage was induced in male Wistar rats through a repeat injection of autologous blood at a 48-hour interval. Rats subjected or not subjected to SAH received a 30-mg/kg baicalein injection 3 hours after SAH and daily for 6 consecutive days, and results were compared with those obtained in vehicle-treated control rats. Mortality of the rats was recorded. Neurological outcome was assessed daily. Cerebrospinal fluid dialysates were collected and examined for glutamate concentrations. Cerebral vasospasm (CVS), brain water content, neuron variability, expression of glutamate transporter-1 (GLT-1), immunoreactivity of astrocyte, and level of malondialdehyde, activities of superoxide dismutase (SOD), and catalase in brain tissues content were determined on post-SAH Day 7.

RESULTS

Mortality rate, neuronal degeneration, brain water content, and CVS were decreased and neurological function improved in the baicalein-treated rats. Baicalein increased astrocyte activity and preserved GLT-1, which attenuated the glutamate surge after SAH. Baicalein also provided antioxidative stress by preserving activities of SOD and catalase and decreased malondialdehydelevel after SAH. The glutamate, body weight, neurological scores, and glial fibrillary acidic protein activity were significantly correlated. The CVS was correlated with neuronal degeneration, and GLT-1 was correlated with oxidative stress.

CONCLUSIONS

Early baicalein treatment attenuated CVS and limited neurological injury following SAH. These data may indicate clinical utility for baicalein as an adjunct therapy to reduce brain injury and improve patient outcomes.

Early brain injury: a common mechanism in subarachnoid hemorrhage and global cerebral ischemia

Early brain injury (EBI) has become an area of extreme interest in the recent years and seems to be a common denominator in the pathophysiology of global transient ischemia and subarachnoid hemorrhage (SAH). In this paper, we highlight the importance of cerebral hypoperfusion and other mechanisms that occur in tandem in both pathologies and underline their possible roles in triggering brain injury after hemorrhagic or ischemic strokes.

Minimally invasive procedures for intracerebral hematoma evacuation in early stages decrease perihematomal glutamate level and improve neurological function in a rabbit model of ICH

INTRODUCTION

To observe the effects of performing a minimally invasive procedure at different stages after intracerebral hemorrhage (ICH) on perihematomal glutamate level and neurological function.

METHODS

Forty-eight rabbits were randomly placed into a model control group (MC group, 24 rabbits) or a minimally invasive group (MI group, 24 rabbits). An ICH model was established in all of the animals. In the MI group, the ICH was evacuated by minimally invasive procedures in 6h (6 rabbits), 12h (6 rabbits), 18h (6 rabbits) and 24h (6 rabbits) after the ICH model was successfully induced. All of the animals were sacrificed within 48h after the hematoma was evacuated by surgery. A neurological deficit score was determined, and the perihematomal glutamate level and the BBB permeability were measured.

RESULTS

The neurological deficit score, perihematomal glutamate level and BBB permeability of the MI group were decreased significantly compared with the MC group. Performing the minimally invasive procedures in 6-12 h after ICH showed the most significant decreases of the glutamate level, BBB permeability and neurological deficit score.

CONCLUSIONS

The optimal time window of performing the minimally invasive procedures for the intracerebral hematoma evacuation might be within 6-12 h after hemorrhage.

The neuro-behavioral profile in rats after subarachnoid hemorrhage

Despite significant advancements in the understanding of the pathophysiological mechanisms of subarachnoid hemorrhage (SAH), little is known about the emotional consequences. The primary goal of this study was to describe the locomotor and behavioral patterns in rats following both a single-injection and double-injection model of SAH. In 48 rats, SAH was induced by injecting 0.3 ml of autologous arterial blood into the cisterna magnum (single-hemorrhagic model). In 24 of these rats, post-SAH vasospasm was induced by a repeated injection of blood into the cisterna magnum 24h later (double-hemorrhagic model). In 24 additional rats, 0.3 ml of saline was injected into the cisterna magnum (sham group). Neurological performance was assessed at 24, 48 h, 1, 2 and 3 weeks after SAH. Four behavioral tests were performed for 3 weeks after SAH for the duration of 6 consequent days, in the following order: open field test, sucrose preference test, elevated plus maze test and forced swimming test. Following both, a single and double-hemorrhagic models of SAH, rats were found to have significant behavioral abnormalities on the open field test, sucrose preference test, elevated plus maze test, and forced swimming test. A more prominent disability was found in rats that underwent the double-hemorrhagic model of SAH than rats that underwent the single-hemorrhagic model. Both a single and double injection model of rats SAH are associated with significant behavioral disturbances including locomotor abnormalities, depressive behavior and increased anxiety, even as early as 3 weeks after SAH.

The effect of blood glutamate scavengers oxaloacetate and pyruvate on neurological outcome in a rat model of subarachnoid hemorrhage

Blood glutamate scavengers have been shown to effectively reduce blood glutamate concentrations and improve neurological outcome after traumatic brain injury and stroke in rats. This study investigates the efficacy of blood glutamate scavengers oxaloacetate and pyruvate in the treatment of subarachnoid hemorrhage (SAH) in rats. Isotonic saline, 250 mg/kg oxaloacetate, or 125 mg/kg pyruvate was injected intravenously in 60 rats, 60 minutes after induction of SAH at a rate of 0.1 ml/100 g/min for 30 minutes. There were 20 additional rats that were used as a sham-operated group. Blood samples were collected at baseline and 90 minutes after SAH. Neurological performance was assessed at 24 h after SAH. In half of the rats, glutamate concentrations in the cerebrospinal fluid were measured 24 h after SAH. For the remaining half, the blood brain barrier permeability in the frontal and parieto-occipital lobes was measured 48 h after SAH. Blood glutamate levels were reduced in rats treated with oxaloacetate or pyruvate at 90 minutes after SAH (p < 0.001). Cerebrospinal fluid glutamate was reduced in rats treated with pyruvate (p < 0.05). Neurological performance was significantly improved in rats treated with oxaloacetate (p < 0.05) or pyruvate (p < 0.01). The breakdown of the blood brain barrier was reduced in the frontal lobe in rats treated with pyruvate (p < 0.05) and in the parieto-occipital lobes in rats treated with either pyruvate (p < 0.01) or oxaloacetate (p < 0.01). This study demonstrates the effectiveness of blood glutamate scavengers oxaloacetate and pyruvate as a therapeutic neuroprotective strategy in a rat model of SAH.

Astrocyte-derived VEGF-A drives blood-brain barrier disruption in CNS inflammatory disease

In inflammatory CNS conditions such as multiple sclerosis (MS), current options to treat clinical relapse are limited, and more selective agents are needed. Disruption of the blood-brain barrier (BBB) is an early feature of lesion formation that correlates with clinical exacerbation, leading to edema, excitotoxicity, and entry of serum proteins and inflammatory cells. Here, we identify astrocytic expression of VEGF-A as a key driver of BBB permeability in mice. Inactivation of astrocytic Vegfa expression reduced BBB breakdown, decreased lymphocyte infiltration and neuropathology in inflammatory and demyelinating lesions, and reduced paralysis in a mouse model of MS. Knockdown studies in CNS endothelium indicated activation of the downstream effector eNOS as the principal mechanism underlying the effects of VEGF-A on the BBB. Systemic administration of the selective eNOS inhibitor cavtratin in mice abrogated VEGF-A-induced BBB disruption and pathology and protected against neurologic deficit in the MS model system. Collectively, these data identify blockade of VEGF-A signaling as a protective strategy to treat inflammatory CNS disease.

The pathophysiological time window study of performing minimally invasive procedures for the intracerebral hematoma evacuation in rabbit

The objective of this study was to observe the pathophysiological time window of performing minimally invasive procedures for the intracerebral hematoma evacuation. Thirty-six rabbits were randomly placed in either a normal control group (NC group, 6 rabbits), a model control group (MC group, 6 rabbits) or a minimally invasive group (MI group, 24 rabbits). A model of intracerebral hemorrhage (ICH) was established in the MC and MI groups. In the MI group, the intracerebral hematoma was evacuated by stereotactic minimally invasive procedures over 6h (6 rabbits), 12h (6 rabbits), 18 h (6 rabbits) and 24h (6 rabbits), following successful induction of ICH. All of the animals in each group were sacrificed 48 h after the successful induction of ICH. Perihematomal brain tissues were removed to determine the glutamate level, BBB permeability and brain water content (BWC). The perihematomal glutamate level, BBB permeability and the BWC in the MI group were significantly decreased compared with those of the MC group. Performing minimally invasive procedures for evacuation of ICH in 6h showed the most remarkable decrease of the glutamate level, BBB permeability and BWC, followed by a significant difference observed at 12h within the MI subgroups. Performing minimally invasive procedures in early stages after ICH for the hematoma evacuation could decrease the perihematomal glutamate level, BBB permeability and BWC significantly. The pathophysiological time window of minimally invasive procedures for hematoma evacuation might be 6-12h after hemorrhage.

The importance of early brain injury after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a medical emergency that accounts for 5% of all stroke cases. Individuals affected are typically in the prime of their lives (mean age 50 years). Approximately 12% of patients die before receiving medical attention, 33% within 48 h and 50% within 30 days of aSAH. Of the survivors 50% suffer from permanent disability with an estimated lifetime cost more than double that of an ischemic stroke. Traditionally, spasm that develops in large cerebral arteries 3-7 days after aneurysm rupture is considered the most important determinant of brain injury and outcome after aSAH. However, recent studies show that prevention of delayed vasospasm does not improve outcome in aSAH patients. This finding has finally brought in focus the influence of early brain injury on outcome of aSAH. A substantial amount of evidence indicates that brain injury begins at the aneurysm rupture, evolves with time and plays an important role in patients' outcome. In this manuscript we review early brain injury after aSAH. Due to the early nature, most of the information on this injury comes from animals and few only from autopsy of patients who died within days after aSAH. Consequently, we began with a review of animal models of early brain injury, next we review the mechanisms of brain injury according to the sequence of their temporal appearance and finally we discuss the failure of clinical translation of therapies successful in animal models of aSAH.

Minimally invasive procedures for evacuation of intracerebral hemorrhage reduces perihematomal glutamate content, blood-brain barrier permeability and brain edema in rabbits

BACKGROUND

To observe the effects of the minimally invasive removal of an intracerebral hematoma on the glutamate concentration, blood-brain barrier (BBB) permeability and brain water content in the brain tissue surrounding the hematoma and to provide a theoretical basis for minimally invasive removal of intracerebral hematomas.

METHODS

Thirty rabbits (2.8-3.4 kg body weight) were selected to establish a model of intracerebral hemorrhage, and they were randomly divided into a model control group and a minimally invasive group after the model was prepared successfully. The intracerebral hematoma was evacuated by stereotactic procedures in minimally invasive group 6 h after the model was established. The glutamate content, the permeability of the BBB and the brain water content in perihematomal brain tissues were determined and compared between the two groups.

RESULTS

The glutamate content, the permeability of the BBB and the brain water content in the perihematomal brain tissues were significantly decreased compared to the model control group 1, 3, and 7 days after the minimally invasive removal of the intracerebral hematoma.

CONCLUSIONS

Minimally invasive surgery for removal of an intracerebral hematoma could significantly reduce the glutamate content, BBB permeability and the brain water content in perihematomal brain tissues.

Improvement in neurological outcome and abolition of cerebrovascular endothelin B and 5-hydroxytryptamine 1B receptor upregulation through mitogen-activated protein kinase kinase 1/2 inhibition after subarachnoid hemorrhage in rats

OBJECT

Delayed cerebral ischemia after subarachnoid hemorrhage (SAH) remains a major cause of death and disability. It has been hypothesized that cerebrovascular upregulation of vasoconstrictor receptors is a key step in the development of delayed cerebral ischemia. Upregulation of endothelin-B (ET(B)) and 5-hydroxytryptamine 1B (5-HT(1B)) receptors has been demonstrated in cerebral artery smooth muscles in the delayed ischemic phase after experimental SAH, and intracellular signaling via the mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinase 1/2 pathway has been shown to be involved in this upregulation. The aim in the present study was to determine whether treatment with the MEK1/2 inhibitor U0126 can prevent cerebrovascular receptor upregulation and improve functional outcome after experimental SAH in rats.

METHODS

Subarachnoid hemorrhage was induced in male Sprague-Dawley rats by the injection of 250 μl of autologous blood into the basal cisterns. Either U0126 or vehicle was intracisternally administered at 6, 12, 24, and 36 hours after SAH. Smooth muscle ET(B) and 5-HT(1B) receptor upregulation was studied in isolated cerebral artery segments through immunohistochemical and myographic studies of contractile responses to receptor-specific agonists. Gross sensorimotor function in the rats after SAH was assessed using a rotating pole test.

RESULTS

Contractile concentration-response curves for middle cerebral artery (MCA) and basilar artery (BA) segments to endothelin-1 (ET-1) and 5-carboxamidotryptamine (5-CT) were shifted leftward for SAH-induced compared with shamoperated rats due to enhanced contractile responses to individual doses of the agonists (for example, contractile responses of the BA to 3 × 10(-10) M of ET-1 and 3 × 10(-7) M of 5-CT were 9.98 ± 5.01% and 16.75 ± 3.62% of the maximal contractile capacity, respectively, in sham-operated rats and 62.78 ± 9.9% and 45.44 ± 10.62%, respectively, in SAH-induced rats). In vivo treatment with 0.19 μg/kg U0126 normalized responses in the SAH-induced rats to levels in the sham-operated rats. Protein expression of ET(B) and 5-HT(1B) receptors in cerebrovascular smooth muscles from SAH-induced rats was increased to 175 ± 33.17% and 167.7 ± 24.74%, respectively, of the levels in sham-operated rats. Endothelin-B and 5-HT(1B) expression levels in U0126-treated SAH-induced rats were at the levels in sham-operated rats (101.9 ± 13.38% and 91.44 ± 16.75%, respectively). In a rotating pole test used to assess gross sensorimotor function on the 2nd day after surgery, sham-operated rats achieved an average score of 5.37 ± 0.23, SAH-induced rats scored 3.35 ± 0.67, and SAH-induced U0126-treated rats scored 5.00 ± 0.4.

CONCLUSIONS

The authors demonstrated that experimental SAH induces upregulation of ET(B) and 5-HT(1B) receptors in cerebrovascular smooth muscles and that treatment with the MEK1/2 inhibitor U0126 abolishes this receptor upregulation. They also demonstrated that experimental SAH results in sensorimotor deficits as assessed by a rotating pole test. These deficits were alleviated by U0126 treatment, suggesting that cerebrovascular receptor upregulation is critical for the functional outcome of delayed cerebral ischemia. The authors suggest that inhibition of MEK1/2 may be a promising new SAH treatment strategy.

Elucidating novel mechanisms of brain injury following subarachnoid hemorrhage: an emerging role for neuroproteomics

Subarachnoid hemorrhage (SAH) is a devastating neurological injury associated with significant patient morbidity and death. Since the first demonstration of cerebral vasospasm nearly 60 years ago, the preponderance of research has focused on strategies to limit arterial narrowing and delayed cerebral ischemia following SAH. However, recent clinical and preclinical data indicate a functional dissociation between cerebral vasospasm and neurological outcome, signaling the need for a paradigm shift in the study of brain injury following SAH. Early brain injury may contribute to poor outcome and early death following SAH. However, elucidation of the complex cellular mechanisms underlying early brain injury remains a major challenge. The advent of modern neuroproteomics has rapidly advanced scientific discovery by allowing proteome-wide screening in an objective, nonbiased manner, providing novel mechanisms of brain physiology and injury. In the context of neurosurgery, proteomic analysis of patient-derived CSF will permit the identification of biomarkers and/or novel drug targets that may not be intuitively linked with any particular disease. In the present report, the authors discuss the utility of neuroproteomics with a focus on the roles for this technology in understanding SAH. The authors also provide data from our laboratory that identifies high-mobility group box protein-1 as a potential biomarker of neurological outcome following SAH in humans.

Neurological and neurobehavioral assessment of experimental subarachnoid hemorrhage

About 50% of humans with aneurysmal subarachnoid hemorrhage (SAH) die and many survivors have neurological and neurobehavioral dysfunction. Animal studies usually focused on cerebral vasospasm and sometimes neuronal injury. The difference in endpoints may contribute to lack of translation of treatments effective in animals to humans. We reviewed prior animal studies of SAH to determine what neurological and neurobehavioral endpoints had been used, whether they differentiated between appropriate controls and animals with SAH, whether treatment effects were reported and whether they correlated with vasospasm. Only a few studies in rats examined learning and memory. It is concluded that more studies are needed to fully characterize neurobehavioral performance in animals with SAH and assess effects of treatment.

Effects of exogenous excitatory amino acid neurotransmitters on blood-brain barrier disruption in focal cerebral ischemia

This study was performed to determine whether exogenous N-methyl-D: -aspartate (NMDA) or alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) would aggravate blood-brain barrier (BBB) disruption in focal cerebral ischemia in rats. Forty-five minutes after middle cerebral artery (MCA) occlusion, one of the following patches was applied to the exposed ischemic cerebral cortex of each rat: normal saline (control), 10(-5) M AMPA, 10(-4) M AMPA, 10(-5) M NMDA, or 10(-4) M NMDA. At 1 h after MCA occlusion, BBB permeability was determined by measuring the transfer coefficient (Ki) of (14)C-alpha-aminoisobutyric acid ((14)C-AIB). In all experimental groups, the Ki of the ischemic cortex (IC) was higher than that of the corresponding contralateral cortex (CC). The Ki of the IC of the animals treated with 10(-4) M AMPA or 10(-4) M NMDA was higher (+41%: P < 0.05 and +33%: P < 0.05, respectively) than that of the control animals. Our data demonstrated that exogenous NMDA or AMPA could further aggravate the BBB disruption in focal cerebral ischemia. Any insult increasing the release of excitatory neurotransmitters could further aggravate BBB disruption and brain edema during the ischemic period.