Neurovascular Protection Reduces Early Brain Injury After Subarachnoid Hemorrhage

Sulforaphane preconditioning of the Nrf2/HO-1 defense pathway protects the cerebral vasculature against blood-brain barrier disruption and neurological deficits in stroke

Disruption of the blood-brain barrier (BBB) and cerebral edema are the major pathogenic mechanisms leading to neurological dysfunction and death after ischemic stroke. The brain protects itself against infarction via activation of endogenous antioxidant defense mechanisms, and we here report the first evidence that sulforaphane-mediated preactivation of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream target heme oxygenase-1 (HO-1) in the cerebral vasculature protects the brain against stroke. To induce ischemic stroke, Sprague-Dawley rats were subjected to 70 min middle cerebral artery occlusion (MCAo) followed by 4, 24, or 72 h reperfusion. Nrf2 and HO-1 protein expression was upregulated in cerebral microvessels of peri-infarct regions after 4-72 h, with HO-1 preferentially associated with perivascular astrocytes rather than the cerebrovascular endothelium. In naïve rats, treatment with sulforaphane increased Nrf2 expression in cerebral microvessels after 24h. Upregulation of Nrf2 by sulforaphane treatment prior to transient MCAo (1h) was associated with increased HO-1 expression in perivascular astrocytes in peri-infarct regions and cerebral endothelium in the infarct core. BBB disruption, lesion progression, as analyzed by MRI, and neurological deficits were reduced by sulforaphane pretreatment. As sulforaphane pretreatment led to a moderate increase in peroxynitrite generation, we suggest that hormetic preconditioning underlies sulforaphane-mediated protection against stroke. In conclusion, we propose that pharmacological or dietary interventions aimed to precondition the brain via activation of the Nrf2 defense pathway in the cerebral microvasculature provide a novel therapeutic approach for preventing BBB breakdown and neurological dysfunction in stroke.

Nuclear factor-κB/Bcl-XL pathway is involved in the protective effect of hydrogen-rich saline on the brain following experimental subarachnoid hemorrhage in rabbits

Early brain injury (EBI), a significant contributor to poor outcome after subarachnoid hemorrhage (SAH), is intimately associated with neuronal apoptosis. Recently, the protective role of hydrogen (H2 ) in the brain has been widely studied, but the underlying mechanism remains elusive. Numerous studies have shown nuclear factor-κB (NF-κB) as a crucial survival pathway in neurons. Here we investigated the role of H2 in EBI following SAH, focusing on the NF-κB pathway. A double blood injection model was used to produce experimental SAH, and H2 -rich saline was injected intraperitoneally. NF-κB activity within the occipital cortex was measured. Immunofluorescence was performed to demonstrate the activation of NF-κB; Bcl-xL and cleaved caspase-3 were determined via Western blot. Gene expression of Bcl-xL was detected by real-time PCR, and TUNEL and Nissl staining were performed to illustrate brain injury in the occipital cortex. SAH induced a significant increase of cleaved caspase-3. Correspondingly, TUNEL staining demonstrated obvious neuronal apoptosis following SAH. In contrast, H2 treatment markedly increased NF-κB activity and the expression of Bcl-xL and decreased the level of cleaved caspase-3. Additionally, H2 treatment significantly reduced post-SAH neuronal apoptosis. The current study shows that H2 treatment alleviates EBI in the rabbits following SAH and that NF-κB/Bcl-xL pathway is involved in the protective role of H2 .

Protective effects of urinary trypsin inhibitor on vascular permeability following subarachnoid hemorrhage in a rat model

AIMS

Inflammation and apoptosis play important roles in increasing vascular permeability following subarachnoid hemorrhage (SAH). The objective of this study was to evaluate whether urinary trypsin inhibitor (UTI), a serine protease inhibitor, attenuates vascular permeability by its antiinflammatory and antiapoptotic effects after experimental SAH.

METHODS

Subarachnoid hemorrhage models were established in adult male Sprague-Dawley rats by endovascular perforation. UTI was administered by intraperitoneal injection immediately following SAH. Brain edema was assessed by magnetic resonance imaging (MRI) at 24 h after SAH. Neurological deficits, brain water content, vascular permeability, malondialdehyde (MDA) concentration, and myeloperoxidase (MPO) activity were evaluated. Immunohistochemical staining and Western blot were used to explore the underlying protective mechanism of UTI.

RESULTS

Urinary trypsin inhibitor 50,000 U/kg significantly attenuated brain edema and neurological deficits and reduced vascular permeability at 24 h after SAH. MDA concentration and MPO activity in hippocampus were significantly decreased with UTI treatment. Furthermore, the levels of phosphorylated JNK, NF-κB (p65), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and proapoptotic protein p53, caspase-3 were elevated in the microvascular endothelial cells of the hippocampus after SAH, which were alleviated with UTI treatment.

CONCLUSION

Urinary trypsin inhibitor reduced vascular permeability after SAH through its antiinflammatory and antiapptotic effects via blocking the activity of JNK, NF-κB, and p53.

Obestatin alleviates subarachnoid haemorrhage-induced oxidative injury in rats via its anti-apoptotic and antioxidant effects

OBJECTIVE

The aim was to investigate the putative anti-inflammatory and anti-apoptotic effect of obestatin in a rat model of subarachnoidal haemorrhage (SAH).

METHODS

To induce SAH, rats were injected with 0.3 mL blood into their cisterna magna. At 48 hours rats were decapitated after neurological examination. Blood-brain barrier (BBB) permeability, brain water content, oxidative stress markers and histological analysis were done in brain tissue.

RESULTS

The results showed that neurological examination scores were increased in the SAH group and, moreover, BBB permeability was impaired and oedema formed. SAH resulted in increased levels of plasma tumour necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 levels and caspase-3 activity. Lipid peroxidation and protein oxidation levels and myeloperoxidase activity were all increased in the brain tissue, with concomitant decreases in antioxidant enzymes. On the other hand, SAH-induced neurological impairment and oxidative brain injury were ameliorated in the obestatin-treated group.

CONCLUSION

The present study provides the first evidence that peripheral administration of obestatin exerts potent anti-inflammatory and neuroprotective effects in SAH-induced oxidative damage by maintaining a balance in oxidant-antioxidant status through the augmentation of endogenous antioxidants and the inhibition of pro-inflammatory mediators.

Neuroprotective effect of tea polyphenols on oxyhemoglobin induced subarachnoid hemorrhage in mice

Tea polyphenols are of great benefit to the treatment of several neurodegenerative diseases. In order to explore the neuroprotective effects of tea polyphenols and their potential mechanisms, an established in vivo subarachnoid hemorrhage (SAH) model was used and alterations of mitochondrial function, ATP content, and cytochrome c (cyt c) in cerebral cortex were detected. This study showed that the alteration of mitochondrial membrane potential was an early event in SAH progression. The trend of ATP production was similar to that of mitochondrial membrane potential, indicating that the lower the mitochondrial membrane potential, lesser the ATP produced. Due to mitochondrial dysfunction, more cyt c was released in the SAH group. Interestingly, the preadministration of tea polyphenols significantly rescued the mitochondrial membrane potential to basal level, as well as the ATP content and the cyt c level in the brain cortex 12 h after SAH. After pretreatment with tea polyphenols, the neurological outcome was also improved. The results provide strong evidence that tea polyphenols enhance neuroprotective effects by inhibiting polarization of mitochondrial membrane potential, increasing ATP content, and blocking cyt c release.

Interference of apoptosis in the pathophysiology of subarachnoid hemorrhage

Programmed cell death is crucial for the correct development of the organism and the clearance of harmful cells like tumor cells or autoreactive immune cells. Apoptosis is initiated by the activation of cell death receptors and in most cases it is associated with the activation of the cysteine proteases, which lead to apoptotic cell death. Cells shrink, chromatin clumps and forms a large, sharply demarcated, crescent-shaped or round mass; the nucleus condenses, apoptotic bodies are formed and eventually dead cells are engulfed by a neighboring cell or cleared by phagocytosis. The authors have summarized the most important data concerning apoptosis in subarachnoid hemorrhage that have been issued in the medical literature in the last 20 years.

Acute microvascular changes after subarachnoid hemorrhage and transient global cerebral ischemia

Subarachnoid hemorrhage and transient global cerebral ischemia result in similar pathophysiological changes in the cerebral microcirculation. These changes include microvascular constriction, increased leukocyte-endothelial interactions, blood brain barrier disruption, and microthrombus formation. This paper will look at various animal and preclinical studies that investigate these various microvascular changes, perhaps providing insight in how these microvessels can be a therapeutic target in both subarachnoid hemorrhage and transient global cerebral ischemia.

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.

17β-Estradiol attenuates secondary injury through activation of Akt signaling via estrogen receptor alpha in rat brain following subarachnoid hemorrhage

BACKGROUND

Apoptosis is implicated in vasospasm and the long-term sequelae of subarachnoid hemorrhage (SAH). This study tested the hypothesis that attenuation of SAH-induced apoptosis after 17β-estradiol (E2) treatment is associated with an increase in phosphorylation of Akt via estrogen receptor-α (ER-α) in rats.

MATERIALS AND METHODS

We examined the expression of phospho-Akt, ERα and ERβ, and apoptosis in cerebral cortex, hippocampus, and dentate gyrus in a two-hemorrhage SAH model in rats. We subcutaneously implanted other rats with a silicone rubber tube containing E2; they received daily injections of nonselective estrogen receptor antagonist (ICI 182,780), selective ERα-selective antagonist (methyl-piperidino-pyrazole), or ERβ-selective antagonist (R,R-tetrahydrochrysene) after the first hemorrhage.

RESULTS

At 7 d after the first SAH, protein levels of phospho-Akt and ERα were significantly decreased and caspase-3 was significantly increased in the dentate gyrus. The cell death assay revealed that DNA fragmentation was significantly increased in the dentate gyrus. Those actions were reversed by E2 and blocked by ICI 182,780 and methyl-piperidino-pyrazole, but not R,R-tetrahydrochrysene. However, there were no significant changes in the expression of the protein levels of phospho-Akt, ERα, ERβ, and caspase-3, and DNA fragmentation after SAH.

CONCLUSIONS

The present study shows that a beneficial effect of E2 in attenuating SAH-induced apoptosis is associated with activation of the expression of phospho-Akt and ERα, and alteration in caspase-3 protein expression via an ERα-dependent mechanism in the dentate gyrus. These data support further the investigation of E2 in the treatment of SAH in humans.

Cerebral microvasculature is an early target of subarachnoid hemorrhage

Most subarachnoid hemorrhage (SAH) patients exhibit clinical signs of cerebral ischemia at admission but no angiographic vasospasm. Consequently, the source of early cerebral ischemia is not understood. Parenchymal microvessels may contribute to early cerebral ischemia, but the low resolution of current imaging has prevented their analysis in SAH patients. Animal studies demonstrated that early after SAH structure and function of parenchymal vessels are compromised to the level that may very well contribute to early ischemia. We review these studies.

A pan-caspase inhibitor reduces myocyte apoptosis and neuropathic pain in rats with chronic constriction injury of the sciatic nerve

BACKGROUND

Chronic constriction injury is a widely used model for neuropathic pain in rats. It presents with symptoms resembling human neuropathic pain, such as spontaneous pain, hyperalgesia, and allodynia. Recently, myocyte apoptosis was found in neuropathic rats as a possible promoter of pain and motor dysfunction. Our aim in this study was to demonstrate whether muscle cell apoptosis contributes to neuropathic pain in this animal model.

METHODS

To clarify this issue, we examined pain, nutritive perfusion, and inflammation in muscle tissue as well as myocyte apoptosis in rats with neuropathic pain established by chronic constriction injury of the sciatic nerve. Animals received either the pan-caspase inhibitor zVAD (OMe)-fmk (n = 5) or equivalent volumes of vehicle (n = 6). Sham-operated rats served as controls (n = 6).

RESULTS

At day 4 after nerve ligation, there were no signs of perfusion failure or muscle tissue inflammation in all experimental groups. However, animals treated with the vehicle had marked myocyte apoptosis, which was found almost completely blocked in zVA-Dtreated animals. The zVA-Dtreated animals presented with a significant reduction of pain upon heat, cold, and mechanical stimulation comparable with values found in sham controls.

CONCLUSIONS

Myocyte apoptosis possibly contributes to thermal and mechanical allodynia in this experimental model for neuropathic pain. The development of neuropathic pain symptoms did not depend on disturbances in microcirculation or muscle tissue inflammation.

Neuroprotective effect of Cyclosporin A on the development of early brain injury in a subarachnoid hemorrhage model: a pilot study

Cyclosporin A (CsA) has been demonstrated to be neuroprotective in ischemic and traumatic brain injuries by inhibiting mitochondrial permeability transition pore (mPTP) opening, thereby maintaining mitochondrial homeostasis and inhibiting pro-apoptotic protein release. The effects of CsA on early brain injury (EBI) after subarachnoid hemorrhage (SAH), however, have not been investigated. This study was designed to explore the effects of CsA on apoptotic signaling pathways and EBI after experimental SAH using four equal groups (n=36) of adult male SD rats, including the sham group, SAH+vehicle group, SAH+CsA2 group, and SAH+CsA10 group. The rat SAH model was induced by injection of 0.3ml non-heparinized arterial blood into the prechiasmatic cistern. In the SAH+CsA2 and SAH+CsA10 groups, a dose of 2mg/kg and 10mg/kg CsA was directly administered by intercarotid injection at 15min and again 24h after SAH induction. Cerebral tissue samples were extracted 48h after SAH. Increased expressions of Cytochrome C, apoptosis-inducing factor (AIF), and cleaved caspase-3 were observed in the cerebral cortex after SAH. Treatment with high dose (10mg/kg) CsA markedly decreased expressions of Cytochrome C, AIF, and cleaved caspase-3, and inhibited apoptosis pathways. Administration of CsA following SAH significantly ameliorated EBI, including cortical apoptosis, brain edema, blood-brain barrier (BBB) impairment, and neurobehavioral deficits. These findings suggest that early administration of CsA may ameliorate EBI and provide neuroprotection in the SAH model through potential mechanisms that include blockage of mPTP opening and inhibition of apoptotic cell death pathways.

Heparin reduces neuroinflammation and transsynaptic neuronal apoptosis in a model of subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) can lead to disabling motor, cognitive, and neuropsychological abnormalities. Part of the secondary injury to cerebral tissues associated with SAH is attributable to the neuroinflammatory response induced by blood. Heparin is a pleiotropic compound that reduces inflammatory responses in conditions outside the central nervous system. Using a model of SAH devoid of global insult, we evaluated the effect of delayed intravenous (IV) infusion of heparin, at a dose that does not produce therapeutic anticoagulation, on neuroinflammation, myelin preservation, and apoptosis. Adult male rats underwent bilateral stereotactic injections of autologous blood (50 μL) into the subarachnoid space of the entorhinal cortex. The rats were implanted with mini-osmotic pumps that delivered either vehicle or unfractionated heparin (10 U/kg/h IV) beginning 12 h after SAH. No mechanical or hemorrhagic injury was observed in the hippocampus. In vehicle controls assessed at 48 h, SAH was associated with robust neuroinflammation in the adjacent cortex [neutrophils, activated phagocytic microglia, nuclear factor-kappa B, tumor necrosis factor-alpha, and interleukin-1beta] and neurodegeneration (Fluoro-Jade C staining and loss of NeuN). In the hippocampus, a muted neuroinflammatory response was indicated by Iba1-positive, ED1-negative microglia exhibiting an activated morphology. The perforant pathway showed Fluoro-Jade C staining and demyelination, and granule cells of the dentate gyrus had pyknotic nuclei, labeled with Fluoro-Jade C and showed upregulation of cleaved caspase-3, consistent with transsynaptic apoptosis. Administration of heparin significantly reduced neuroinflammation, demyelination, and transsynaptic apoptosis. We conclude that delayed IV infusion of low-dose unfractionated heparin may attenuate adverse neuroinflammatory effects of SAH.

p53-induced uncoupling expression of aquaporin-4 and inwardly rectifying K+ 4.1 channels in cytotoxic edema after subarachnoid hemorrhage

AIMS

To investigate the mechanism behind cytotoxic edema formation following subarachnoid hemorrhage (SAH).

METHODS

We explored the role of aquaporin-4 (AQP4), inwardly rectifying K(+) 4.1 (Kir4.1) channels and their upstream orchestrators p53 and p38MAPK in this process. A p53 inhibitor, pifithrin-α (PFT-α) was administered intraperitoneally to rats undergoing SAH by endovascular perforation. Totally, 98 male SD rats were categorized into sham, SAH, SAH+ dimethyl sulfoxide (DMSO), SAH+ 0.2 or 2.0 mg/kg PFT-α groups. At 24 h after SAH, MRI (diffusion-weighted imaging [DWI]), immunohistochemistry, and Western blot were used.

RESULTS

MRI (DWI) showed a significant cytotoxic edema in the brain following SAH with PFT-α therapy reducing it. Immunohistochemistry and Western blot showed an increased level of p53, phosphorylated-p38MAPK and AQP4 and a reduced level of Kir4.1; all of which could be reversed following PFT-α treatment. Treble labeling staining revealed colocalization of p53 with phosphorylated-p38MAPK and unmatched expression of AQP4 and Kir4.1 within astrocyte cells.

CONCLUSION

These results indicated p53 mediates the formation of cytotoxic edema in the brain following SAH; an uncoupling expression of AQP4 and Kir4.1 on astrocytic end feet orchestrated by p38MAPK was partly responsible.

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.

Heme activates TLR4-mediated inflammatory injury via MyD88/TRIF signaling pathway in intracerebral hemorrhage

BACKGROUND

Inflammatory injury plays a critical role in intracerebral hemorrhage (ICH)-induced neurological deficits; however, the signaling pathways are not apparent by which the upstream cellular events trigger innate immune and inflammatory responses that contribute to neurological impairments. Toll-like receptor 4 (TLR4) plays a role in inflammatory damage caused by brain disorders.

METHODS

In this study, we investigate the role of TLR4 signaling in ICH-induced inflammation. In the ICH model, a significant upregulation of TLR4 expression in reactive microglia has been demonstrated using real-time RT-PCR. Activation of microglia was detected by immunohistochemistry, cytokines were measured by ELISA, MyD88, TRIF and NF-κB were measured by Western blot and EMSA, animal behavior was evaluated by animal behavioristics.

RESULTS

Compared to WT mice, TLR4(-/-) mice had restrained ICH-induced brain damage showing in reduced cerebral edema and lower neurological deficit scores. Quantification of cytokines including IL-6, TNF-α and IL-1β and assessment of macrophage infiltration in perihematoma tissues from TLR4(-/-), MyD88(-/-) and TRIF(-/-) mice showed attenuated inflammatory damage after ICH. TLR4(-/-) mice also exhibited reduced MyD88 and TRIF expression which was accompanied by decreased NF-κB activity. This suggests that after ICH both MyD88 and TRIF pathways might be involved in TLR4-mediated inflammatory injury possibly via NF-κB activation. Exogenous hemin administration significantly increased TLR4 expression and microglial activation in cultures and also exacerbated brain injury in WT mice but not in TLR4(-/-) mice. Anti-TLR4 antibody administration suppressed hemin-induced microglial activation in cultures and in the mice model of ICH.

CONCLUSIONS

Our findings suggest that heme potentiates microglial activation via TLR4, in turn inducing NF-κB activation via the MyD88/TRIF signaling pathway, and ultimately increasing cytokine expression and inflammatory injury in ICH. Targeting TLR4 signaling may be a promising therapeutic strategy for ICH.

Cell death starts early after subarachnoid hemorrhage

Brain injury begins early after aneurysmal subarachnoid hemorrhage (SAH). Although cell death via apoptosis and necrosis is known to be present in brain 24 h after SAH, it is not known how soon after SAH cell death begins. We have previously described structural changes in rat brain microvessels 10 min after induction of SAH by endovascular puncture. This study examined brain for evidence of cell death beginning 10 min after induction of SAH. Cleaved caspase-3 (cl-caspase-3) staining was evident in vascular and parenchymal cells at 10 min after SAH and was significantly greater than in time-matched, sham-operated controls. The number of cl-caspase-3 positive cells was increased further at 24 h after SAH. TUNEL assay revealed apoptotic cells present at 10 min, with substantially more at 24 h after SAH. Scattered Fluoro-Jade positive neurons appeared at 1h after SAH and their number increased with time. At 1 h Fluoro-Jade positive neurons were present in cortical and subcortical regions but not in hippocampus; at 24h they were also present in hippocampus and were significantly greater in the hemisphere ipsilateral to the vascular puncture. No Fluoro-Jade staining was present in shams. These data demonstrate an early activation of endothelial and parenchymal cells apoptosis and neuronal necrosis after SAH and identifies endpoints that can be targeted to reduce early brain injury after SAH.

Treatment with sodium orthovanadate reduces blood-brain barrier disruption via phosphatase and tensin homolog deleted on chromosome 10 (PTEN) phosphorylation in experimental subarachnoid hemorrhage

Attenuation of blood-brain barrier (BBB) disruption is one of the therapeutic candidates for treatment of subarachnoid hemorrhage (SAH). In this study, the protective effect of sodium orthovanadate (SOV) on BBB disruption was investigated in SAH using the endovascular perforation model. Fifty-five rats were randomly assigned to sham-operated, SAH treated with saline (as a vehicle), or 10 mg/kg SOV groups and were evaluated for neurofunction and Evans blue dye extravasation. The phosphorylation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and mitogen-activated protein kinase (MAPK) and the expression of matrix metalloproteinase-9 (MMP-9), occludin, and collagen-IV were examined by Western blot analyses. Cell death among endothelial cells was revealed by immunofluorescence and terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling staining. SOV significantly improved neurofunction and reduced Evans blue dye extravasation in brains after SAH. SOV phosphorylated PTEN, decreased phospho-JNK and MMP-9, and preserved occludin expression. SOV also attenuated SAH-induced capillary endothelial cell death. The current study showed that SOV was protective against BBB disruption after SAH, possibly via PTEN phosphorylation.

CHOP silencing reduces acute brain injury in the rat model of subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Endoplasmic reticulum stress triggers apoptotic cascades in neurons of the central nervous system after subarachnoid hemorrhage. The aim of this work was to study the mechanism of neuroprotection conferred by targeting cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) in the acute brain injury following subarachnoid hemorrhage.

METHODS

A total of 172 rats were used. Endovascular perforation induced subarachnoid hemorrhage. Two small interfering RNAs for CHOP were injected 24 hours before hemorrhage induction. At 24 or 72 hours, rats were neurologically evaluated and euthanized. The brains were recovered for molecular biology and histology studies.

RESULTS

Western blot analysis revealed effective silencing of CHOP associated with suppression of Bim-Caspase-3 apoptotic pathway. Moreover, the antiapoptotic Bcl2 was found upregulated with CHOP siRNA treatment. A reduced number of TUNEL-positive cells in the subcortex and in the hippocampus reflected histological protection. CHOP siRNA treatment ameliorated intracranial sequelae of and improved functional performance.

CONCLUSIONS

We conclude that CHOP silencing alleviates early brain injury following subarachnoid hemorrhage via inhibiting apoptosis and that CHOP siRNA treatment has a clinical potential for patients with this type of hemorrhagic stroke.

α7 nicotinic acetylcholine receptor agonist PNU-282987 attenuates early brain injury in a perforation model of subarachnoid hemorrhage in rats

BACKGROUND AND PURPOSE

Early brain injury is an important pathological process after subarachnoid hemorrhage (SAH). The goal of this study was to evaluate whether the α7 nicotinic acetylcholine receptor (α7nAChR) agonist PNU-282987 attenuates early brain injury after SAH and whether α7nAChR stimulation is associated with down-regulation of caspase activity via phosphatidylinositol 3-kinase-Akt signaling.

METHODS

The perforation model of SAH was performed, and neurological score, body weight loss, and brain water content were evaluated 24 and 72 hours after surgery. Western blot and immunohistochemistry were used for quantification and localization of phosphorylated Akt and cleaved caspase 3. Neuronal cell death was quantified with TUNEL staining. α7nAChR antagonist methylcaconitine and phosphatidylinositol 3-kinase inhibitor wortmannin were used to manipulate the proposed pathway, and results were quantified with Western blot.

RESULTS

PNU-282987 improved neurological deficits both 24 and 72 hours after surgery and reduced brain water content in left hemispheres 24 hours after surgery. PNU-282987 significantly increased phosphorylated Akt levels and significantly decreased cleaved caspase 3 levels in ipsilateral hemispheres after SAH. Methylcaconitine and wortmannin reversed effects of treatment. Phosphorylated Akt and cleaved caspase 3 were colocalized to neurons in the ipsilateral basal cortex. Phosphorylated Akt was mainly localized in TUNEL-negative cells. PNU-282987 significantly reduced neuronal cell death in the ipsilateral basal cortex.

CONCLUSIONS

α7nAChR stimulation decreased neuronal cell death and brain edema and improved neurological status in a rat perforation model of SAH. α7nAChR stimulation is associated with increasing phosphorylation of Akt and decreasing cleaved caspase 3 levels in neurons.

Reduction of neutrophil activity decreases early microvascular injury after subarachnoid haemorrhage

Background

Subarachnoid haemorrhage (SAH) elicits rapid pathological changes in the structure and function of parenchymal vessels (≤ 100 μm). The role of neutrophils in these changes has not been determined. This study investigates the role of neutrophils in early microvascular changes after SAH

Method

Rats were either untreated, treated with vinblastine or anti-polymorphonuclear (PMN) serum, which depletes neutrophils, or treated with pyrrolidine dithiocarbamate (PDTC), which limits neutrophil activity. SAH was induced by endovascular perforation. Neutrophil infiltration and the integrity of vascular endothelium and basement membrane were assessed immunohistochemically. Vascular collagenase activity was assessed by in situ zymography.

Results

Vinblastine and anti-PMN serum reduced post-SAH accumulation of neutrophils in cerebral vessels and in brain parenchyma. PDTC increased the neutrophil accumulation in cerebral vessels and decreased accumulation in brain parenchyma. In addition, each of the three agents decreased vascular collagenase activity and post-SAH loss of vascular endothelial and basement membrane immunostaining.

Conclusions

Our results implicate neutrophils in early microvascular injury after SAH and indicate that treatments which reduce neutrophil activity can be beneficial in limiting microvascular injury and increasing survival after SAH.

Sampling of CSF via the Cisterna Magna and Blood Collection via the Heart Affects Brain Water Content in a Rat SAH Model

The aim of this study was to evaluate whether sampling of cerebrospinal fluid (CSF) via the cisterna magna and of blood via the heart affects brain water content in a rat subarachnoid hemorrhage (SAH) model. Twenty-nine animals were divided into four groups: sham-operated group with sampling of CSF and blood (Sham S+), sham-operated group without sampling of CSF and blood (Sham S-), SAH group with sampling of CSF and blood (SAH S+), and SAH without sampling of CSF and blood (SAH S-). SAH was induced via endovascular perforation of the left internal carotid artery bifurcation. Cerebrospinal fluid via the cisterna magna and blood via cardiac puncture was collected in the Sham S+ and SAH S+ groups before killing the animals for brain water content measurements. Left hemisphere brain water content was significantly higher in the SAH S- group compared with the Sham S- group (p< 0.05) and in Sham S+ group compared with the Sham S- group (p<0.05). There was no significant difference in brain water content of the left hemisphere between the SAH S+ and Sham S+ groups (p=NS). There was no significant difference in brain water content in other parts of brains. Sampling of CSF and blood affected brain water content in Sham animals and therefore it is not accurate to use these values from Sham animals for comparison with SAH animals.

The novel function of nesfatin-1 as an anti-inflammatory and antiapoptotic peptide in subarachnoid hemorrhage-induced oxidative brain damage in rats

BACKGROUND

There is substantial evidence to suggest that oxidative stress plays a significant role in the development of acute brain injury after subarachnoid hemorrhage (SAH).

OBJECTIVE

To investigate the putative neuroprotective effect of nesfatin-1, a novel peptide with anorexigenic properties, in a rat model of SAH.

METHODS

Male Wistar albino rats were randomly divided into control, saline-treated SAH, and nesfatin-1 (10 μg/kg IP)-treated SAH groups. To induce SAH, rats were injected with 0.3 mL blood into their cisterna magna. Forty-eight hours after SAH induction, neurological examination scores were recorded and the rats were decapitated. Brain tissue samples were taken for the determination of blood-brain barrier (BBB) permeability, brain water content, and oxidative stress markers and for histological analysis.

RESULTS

The neurological examination scores were increased on the second day of SAH induction. SAH resulted in impaired blood-brain barrier and edema, along with increased levels of brain tumor necrosis factor-α, interleukin-1β, interleukin-6, lipid peroxidation, protein carbonylation, and myeloperoxidase activity with concomitant decreases in antioxidant enzymes. Conversely, in the nesfatin-1-treated SAH group, SAH-induced neurological impairment and oxidative brain injury were ameliorated by nesfatin treatment. Furthermore, SAH-induced morphological changes in the basilar arteries were improved by nesfatin-1 treatment, whereas caspase-3 activity and SAH-induced elevations in the plasma levels of proinflammatory cytokines were also depressed by nesfatin-1 treatment.

CONCLUSION

These findings suggest that nesfatin-1, which appears to have antiapoptotic and anti-inflammatory properties, exerts neuroprotection in SAH-induced injury in rats by inhibiting neutrophil infiltration and subsequent release of inflammatory mediators.

Treatment with Z-ligustilide, a component of Angelica sinensis, reduces brain injury after a subarachnoid hemorrhage in rats

Subarachnoid hemorrhage (SAH) is a devastating stroke subtype accounting for approximately 3 to 7% of cases each year. Despite its rarity among the various stroke types, SAH is still responsible for approximately 25% of all stroke fatalities. Although various preventative and therapeutic interventions have been explored for potential neuroprotection after SAH, a considerable percentage of patients still experience serious neurologic and/or cognitive impairments as a result of the primary hemorrhage and/or secondary brain damage that occurs. Z-ligustilide (LIG), the primary lipophilic component of the Chinese traditional medicine radix Angelica sinensis, has been shown to reduce ischemic brain injury via antiapoptotic pathways. Accordingly, in our study, we investigated the neuroprotective potential of LIG after experimental SAH in rats. Rats with SAH that was induced using the established double hemorrhage model were studied with and without LIG treatment. Mortality, neurobehavioral evaluation, brain water content, blood-brain barrier (BBB) permeability, and vasospasm assessment of the basilar artery were measured on days 3 and 7 after injury. Additional testing was done to evaluate for apoptosis using TdT-mediated dUTP-biotin nick end labeling staining as well as immunohistochemistry and Western blotting to identify key proapoptotic/survival proteins, i.e., p53, Bax, Bcl-2, and cleaved caspase-3. The results showed that LIG treatment reduced mortality, neurobehavioral deficits, brain edema, BBB permeability, and cerebral vasospasm. In addition, treatment reduced the number of apoptotic cells in the surrounding brain injury site, which accompanied a marked down-regulation of proapoptotic proteins, p53, and cleaved caspase-3. Our data suggest that LIG may be an effective therapeutic modality for SAH victims by altering apoptotic mechanisms.

Angiopoietin-1 is associated with cerebral vasospasm and delayed cerebral ischemia in subarachnoid hemorrhage

Background

Angiopoietin-1 (Ang-1) and -2 (Ang-2) are keyplayers in the regulation of endothelial homeostasis and vascular proliferation. Angiopoietins may play an important role in the pathophysiology of cerebral vasospasm (CVS). Ang-1 and Ang-2 have not been investigated in this regard so far.

Methods

20 patients with subarachnoid hemorrhage (SAH) and 20 healthy controls (HC) were included in this prospective study. Blood samples were collected from days 1 to 7 and every other day thereafter. Ang-1 and Ang-2 were measured in serum samples using commercially available enzyme-linked immunosorbent assay. Transcranial Doppler sonography was performed to monitor the occurrence of cerebral vasospasm.

Results

SAH patients showed a significant drop of Ang-1 levels on day 2 and 3 post SAH compared to baseline and HC. Patients, who developed Doppler sonographic CVS, showed significantly lower levels of Ang-1 with a sustained decrease in contrast to patients without Doppler sonographic CVS, whose Ang-1 levels recovered in the later course of the disease. In patients developing cerebral ischemia attributable to vasospasm significantly lower Ang-1 levels have already been observed on the day of admission. Differences of Ang-2 between SAH patients and HC or patients with and without Doppler sonographic CVS were not statistically significant.

Conclusions

Ang-1, but not Ang-2, is significantly altered in patients suffering from SAH and especially in those experiencing CVS and cerebral ischemia. The loss of vascular integrity, regulated by Ang-1, might be in part responsible for the development of cerebral vasospasm and subsequent cerebral ischemia.

Blood-brain barrier disruption following subarchnoid hemorrhage may be faciliated through PUMA induction of endothelial cell apoptosis from the endoplasmic reticulum

The blood-brain barrier (BBB) plays a vital role as both a physiologic and physical barrier in regulating the movement of water from the vasculature to the brain. During a subarachnoid hemorrhage (SAH), the BBB is disrupted by a variety of mediators, one of which can result in endothelial cell death. As a result, in the present study, we investigated the role of PUMA (p53 upregulated modulator of apoptosis) following SAH injury in rats. Specifically evaluating whether through the endoplasmic reticulum (ER), PUMA could orchestrate the induction of endothelial cell apoptosis and cause a disruption in the blood-brain barrier integrity. One hundred twelve male Sprague-Dawley rats were randomly divided into 4 groups: sham, SAH, SAH+control siRNA, SAH+PUMA siRNA. Outcomes measured include mortality rate, brain edema, BBB disruption, and neurobehavioral testing. We also used Western blotting techniques to measure the expression of key pro-apoptotic proteins such as BAX, BAK, and DRP1. PUMA siRNA treatment significantly reduced the mortality rate, cerebral edema, neurobehavioral deficits, and BBB disruption as measured by Evans blue assay following SAH injury. The T2WI images showed there was an increase in vasogenic edema in the brain following SAH, which could be alleviated by PUMA siRNA. Immunohistochemical staining and Western blot analysis demonstrated an increased expression of PUMA, BAX, BAK, GRP78 and DRP1 in the microvascular endothelial cells of the hippocampus, which was accompanied with endothelium apoptosis. This study showed that PUMA induced endothelial cell apoptosis may in fact play a significant role in BBB disruption following SAH and its mediation may be through the endoplasmic reticulum. By blocking the activity of PUMA using siRNA, we were able to prevent the accumulation of cerebral edema that occurs following BBB disruption. This translated into a preservation of functional integrity and an improvement in mortality.

Characterizing the role of the neuropeptide substance P in experimental subarachnoid hemorrhage

BACKGROUND

Raised intracranial pressure (ICP) following SAH predicts poor outcome and is due to hemorrhage volume and possibly, brain edema, hydrocephalus and increased volume of circulating intracranial blood. Interventions that reduce edema may therefore reduce ICP and improve outcome. The neuropeptide substance P (SP) mediates vasogenic edema formation in animal models of ischemic stroke, intracerebral hemorrhage and brain trauma, and may contribute to development of increased ICP. SP (NK1 tachykinin receptor) blockade using n-acetyl-l-tryptophan (NAT) reduces edema and improves outcome in these models. This study therefore assessed whether SP mediates edema formation in experimental SAH.

METHODS

SAH was induced in rats by either injection of autologous blood into the prechiasmatic cistern (injection SAH) or by arterial puncture of the Circle of Willis (filament SAH). NAT was injected (i.v.) 30min after SAH induction. Subgroups were assessed for brain water content, SP and albumin immunoreactivity, and functional outcome at 5, 24 and 48h or ICP over 5h.

RESULTS

A secondary ICP increase occurred within 2h of SAH. Brain edema followed filament SAH (p<0.001) and correlated with functional deficits (r=0.8, p<0.01). Increased albumin immunoreactivity (p<0.001) indicated vasogenic edema. However, NAT treatment did not improve ICP, edema or outcome.

CONCLUSIONS

Experimental SAH produced secondary ICP elevation, vasogenic brain edema and functional deficits, although it is unclear if edema contributed to ICP. Blockade of SP did not improve any outcome parameters, suggesting that neurogenic inflammation may be less critical than other factors in these models.

Apoptotic mechanisms for neuronal cells in early brain injury after subarachnoid hemorrhage

OBJECTS

The major causes of death and disability in subarachnoid hemorrhage (SAH) may be early brain injury (EBI) and cerebral vasospasm. Although cerebral vasospasm has been studied and treated by a lot of drugs, the outcome is not improved even if vasospasm is reversed. Based on these data, EBI is considered a primary target for future research, and apoptosis may be involved in EBI after experimental SAH.

METHODS

We reviewed the published literature about the relationship between SAH induced EBI and apoptosis in PubMed.

RESULT

Most available information can be obtained from the endovascular filament perforation animal model. After onset of SAH, intracranial pressure is increased and then cerebral blood flow is reduced. Many factors are involved in the mechanism of apoptotic cell death in EBI after SAH. In the neuronal cells, both intrinsic and extrinsic pathways of apoptosis can occur. Some antiapoptotic drugs were studied and demonstrated a protective effect against EBI after SAH. However, apoptosis in EBI after SAH has been little studied and further studies will provide us more beneficial findings.

CONCLUSIONS

The study of apoptosis in EBI after experimental SAH may give us new therapies for SAH.

Early micro vascular changes after subarachnoid hemorrhage

During the last decade much effort has been invested in understanding the events that occur early after SAH. It is now widely accepted that these early events not only participate in the early ischemic injury but also set the stage for the pathogenesis of delayed vasospasm. That early cerebral ischemia occurs after SAH is documented in both experimental SAH and in human autopsy studies; however, angiographic evidence for vasoconstriction early after SAH is lacking and the source of early ischemic injury is therefore unclear. Recently, the cerebral microvasculature has been identified as an early target of SAH. Changes in the anatomical structure of cerebral microvessels, sufficient to cause functional deficits, are found early after experimental SAH. These changes may explain cerebral ischemia in human in the absence of angiographic evidence of large vessel vasoconstriction. This paper summarizes known alterations in cerebral microvasculature during the first 48 h after SAH.

Metamorphosis of subarachnoid hemorrhage research: from delayed vasospasm to early brain injury

Delayed vasospasm that develops 3–7 days after aneurysmal subarachnoid hemorrhage (SAH) has traditionally been considered the most important determinant of delayed ischemic injury and poor outcome. Consequently, most therapies against delayed ischemic injury are directed towards reducing the incidence of vasospasm. The clinical trials based on this strategy, however, have so far claimed limited success; the incidence of vasospasm is reduced without reduction in delayed ischemic injury or improvement in the long-term outcome. This fact has shifted research interest to the early brain injury (first 72 h) evoked by SAH. In recent years, several pathological mechanisms that activate within minutes after the initial bleed and lead to early brain injury are identified. In addition, it is found that many of these mechanisms evolve with time and participate in the pathogenesis of delayed ischemic injury and poor outcome. Therefore, a therapy or therapies focused on these early mechanisms may not only prevent the early brain injury but may also help reduce the intensity of later developing neurological complications. This manuscript reviews the pathological mechanisms of early brain injury after SAH and summarizes the status of current therapies.

Astrocyte-derived glutathione attenuates hemin-induced apoptosis in cerebral microvascular cells

Intracerebral hemorrhage (ICH) induces neurovascular injury via poorly defined mechanisms. The aim of this study was to determine whether gliovascular communication may restrict hemorrhagic vascular injury. Hemin, a hemoglobin by-product, concentration- and time-dependently increased apoptotic cell death in mouse bEnd.3 cells and in primary human brain microvascular endothelial cells, at least in part, via a caspase-3 dependent pathway. Cell death was preceded by a NFκB-mediated increase in inflammatory gene expression, including upregulation of inducible nitric oxide synthase (iNOS) expression and activity. Functionally, inhibition of iNOS or the addition of a peroxynitrite decomposition catalyst reduced cell death. Interestingly, co-treatment with astrocyte-conditioned media (ACM) reversed hemin-induced NFκB activation, nitrotyrosine formation, and apoptotic cell death, at least in part, via the release of the endogenous antioxidant, reduced glutathione (GSH). Prior treatment of astrocytes with the GSH-depleting agent, DL-buthionine (S,R)-sulfoximine or direct addition of diethyl maleate, a thiol-depleting agent, to ACM reversed the observed protection. In contrast, neither exogenous GSH nor the GSH precursor, N-acetylcysteine, was protective in bEnd.3 cells. Together, these data support an important role for astrocyte-derived GSH in the maintenance of oxidative balance in the vasculature and suggest therapeutic targeting of the GSH system may reduce neurological injury following ICH.

A review of delayed ischemic neurologic deficit following aneurysmal subarachnoid hemorrhage: historical overview, current treatment, and pathophysiology

Delayed ischemic neurologic deficit (DIND) is a serious and poorly understood complication of aneurysmal subarachnoid hemorrhage. Although advances in treatment have improved prognosis for these patients, long-term clinical outcomes remain disappointing. Historically, angiographic vasospasm was thought to result in a DIND, although an increasing body of evidence suggests that this is an oversimplification, because interventions that have effectively targeted angiographic vasospasm have not improved outcome. Consequently, the relationship between angiographic vasospasm and neurologic outcome may be associative rather than causative. Although our understanding of the underlying molecular processes and pathophysiology is improving, responsible mediators or pathways have yet to be identified. The aim of this review is to summarize the key historical events that have helped shape our understanding of the pathophysiology of this phenomenon (microcirculation, autoregulation, microthrombosis, inflammation, apoptosis, spreading depolarization, oxidative stress) and to present the evidence underlying current treatment strategies (hemodynamic therapy, oral nimodipine, endovascular therapy, statins, cerebrospinal fluid drainage, thrombolysis, magnesium) and the translational and clinical research investigating DIND.

The anti-inflammatory and neuroprotective effects of ghrelin in subarachnoid hemorrhage-induced oxidative brain damage in rats

To elucidate the putative neuroprotective effects of ghrelin in subarachnoid hemorrhage (SAH)-induced brain injury, Wistar albino rats (n = 54) were divided into sham-operated control, saline-treated SAH, and ghrelin-treated (10 microg/kg/d IP) SAH groups. The rats were injected with blood (0.3 mL) into the cisterna magna to induce SAH, and were sacrificed 48 h after the neurological examination scores were recorded. In plasma samples, neuron-specific enolase (NSE), S-100beta protein, TNF-alpha, and IL-1beta levels were evaluated, while forebrain tissue samples were taken for the measurement of malondialdehyde (MDA), glutathione (GSH), reactive oxygen species levels, myeloperoxidase (MPO), Na(+)-K(+)-ATPase activity, and DNA fragmentation ratio. Brain tissue samples containing the basilar arteries were obtained for histological examination, while cerebrum and cerebellum were removed for the measurement of blood-brain barrier (BBB) permeability and brain water content. The neurological scores were impaired at 48 h after SAH induction, and SAH caused significant decreases in brain GSH content and Na(+)-K(+)-ATPase activity, and increases in chemiluminescence, MDA levels, and MPO activity. Compared with the control group, the protein levels of NSE, S-100beta, TNF-alpha, and IL-1beta in plasma were also increased, while ghrelin treatment prevented all SAH-induced alterations observed both biochemically and histopathologically. The results demonstrate that ghrelin alleviates SAH-induced oxidative brain damage, and exerts neuroprotection by maintaining a balance in oxidant-antioxidant status, by inhibiting proinflammatory mediators, and preventing the depletion of endogenous antioxidants evoked by SAH.

Cellular microparticles as a marker for cerebral vasospasm in spontaneous subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Spontaneous subarachnoid hemorrhage (SAH) still has a high risk for poor outcome that is frequently attributable to symptomatic cerebral vasospasm (CVS). We hypothesize that cellular microparticles (MP) play a role in the pathogenesis of CVS and may serve as biomarkers for CVS.

METHODS

In 20 consecutive SAH patients, endothelial, leukocyte, platelet, and erythrocyte MP were measured during 15 days after ictus. CVS was detected by transcranial Doppler sonography. Twenty matched volunteers served as healthy controls.

RESULTS

Endothelial, leukocyte, and erythrocyte MP were elevated in SAH patients compared to healthy controls. CD105(+) and CD62e(+) endothelial MP were significantly higher in SAH patients with Doppler sonographic CVS. CD105(+) endothelial MP were especially increased on the days of Doppler sonographic CVS onset. In patients experiencing cerebral infarction attributable to vasospasm, CD41(+) platelet MP were elevated in addition to endothelial MP. CD41(+) platelet MP were significantly higher in patients with any level of disability (modified Rankin Scale score ≥1) compared to those who made a full recovery (modified Rankin Scale score=0) on discharge from hospital.

CONCLUSIONS

Endothelial MP were elevated in patients with SAH. This elevation coincided with the occurrence of Doppler sonographic CVS and therefore could be a novel biomarker for CVS. Platelet MP might be involved in the pathogenesis of cerebral infarction attributable to vasospasm, resulting in neurological morbidity.

Interaction of neurovascular protection of erythropoietin with age, sepsis, and statin therapy following aneurysmal subarachnoid hemorrhage

Object

In a previous randomized controlled trial, the authors demonstrated that acute erythropoietin (EPO) therapy reduced severe vasospasm and delayed ischemic deficits (DIDs) following aneurysmal subarachnoid hemorrhage. In this study, the authors aimed to investigate the potential interaction of neurovascular protection by EPO with age, sepsis, and concurrent statin therapy.

Methods

The clinical events of 80 adults older than 18 years and with < 72 hours of aneurysmal subarachnoid hemorrhage, who were randomized to receive 30,000 U of intravenous EPO-β or placebo every 48 hours for a total of 3 doses, were analyzed by stratification according to age (< or ≥ 60 years), sepsis, or concomitant statin therapy. End points in the trial included cerebral vasospasm and impaired autoregulation on transcranial Doppler ultrasonography, DIDs, and unfavorable outcome at discharge and at 6 months measured with the modified Rankin Scale and Glasgow Outcome Scale. Analyses were performed using the t-test and/or ANOVA for repeated measurements.

Results

Younger patients (< 60 years old) or those without sepsis obtained benefits from EPO by a reduction in vasospasm, impaired autoregulation, and unfavorable outcome at discharge. Compared with nonseptic patients taking EPO, those with sepsis taking EPO had a lower absolute reticulocyte count (nonsepsis vs sepsis, 143.5 vs. 105.8 × 109/L on Day 6; p = 0.01), suggesting sepsis impaired both hematopoiesis and neurovascular protection by EPO. In the EPO group, none of the statin users suffered DIDs (p = 0.078), implying statins may potentiate neuroprotection by EPO.

Conclusions

Erythropoietin-related neurovascular protection appears to be attenuated by old age and sepsis and enhanced by statins, an important finding for designing Phase III trials.

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.

Role of matrix metalloproteinase-9 in apoptosis of hippocampal neurons in rats during early brain injury after subarachnoid hemorrhage

This study investigated the possible involvement of matrix metalloproteinase 9 (MMP-9) in early brain injury (EBI) of subarachnoid hemorrhage (SAH) in rats. MMP-9 activities in hippocampus were examined at 6, 12, 24, 48 and 72 h after SAH. Laminin was detected by immunohistochemistry. Apoptosis of neurons in hippocampus was observed by TUNEL. Brain water content was also examined. MMP-9 activity and the number of apoptotic neurons increased from 12 to 72 h with a peak at 24 h. Laminin was found to decrease at 12 h, reached minimum at 24 h and began to increase from 48 h, which had a negative correlation with apoptotic neurons. The changes of brain water content were found to be coincidence with that of neuronal apoptosis. Our findings suggest that MMP-9 is probably involved in the pathophysiological events of EBI after SAH, through degrading laminin which leads to neuronal anoikis of hippocampus.

Simvastatin activates Akt/glycogen synthase kinase-3beta signal and inhibits caspase-3 activation after experimental subarachnoid hemorrhage

This study was designed to explore the role of simvastatin and its effects on the Akt/GSK3beta survival signal and apoptosis pathway after experimental subarachnoid hemorrhage (SAH). SAH was induced by blood injection into the cisterna magna in New Zealand white rabbits. Increased expression of phospho-Akt and phospho-GSK3beta was observed in brain tissue after SAH. Apoptosis and related proteins, including P53, apoptosis-inducing factor (AIF), cytochrome C, and cleaved caspase-3, were also activated. Simvastatin, at both low dose (10 mg/kg) and high dose (40 mg/kg), further increased expression of phospho-Akt and phospho-GSK3beta, decreased activation of caspase-3, and inhibited apoptosis. Preserved blood-brain barrier and attenuated brain edema were observed following simvastatin treatment. In addition, the neuroprotective effects of simvastatin were blocked by wortmannin (2.5 microg/kg/min), an irreversible PIK3 inhibitor. P53, AIF, and cytochrome C were not affected by simvastatin treatment. Findings from the present study suggest that simvastatin ameliorates acute brain injury after SAH. The potential mechanisms of action include activation of the Akt/GSK3beta survival signal and inhibition of caspase-dependent apoptosis pathway.