Ras Protein Contributes to Cerebral Vasospasm in a Canine Double-Hemorrhage Model

WNK3 Promotes Neuronal Survival after Traumatic Brain Injury in Rats

With-no-lysine kinase 3 (WNK3) is a key regulator of chloride ion transport and neuronal survival in diverse cell types. WNK3 was previously found to regulate the activity of Na⁺-K⁺-2Cl^- cotransporter-1 (NKCC1) in ischemia-associated brain damage. However, the role of WNK3 in traumatic brain injury (TBI) has not yet been studied. A weight-drop TBI model was established in Sprague-Dawley rats. Overexpression and specific inhibition were used to investigate the role of WNK3 in TBI via Western blot, immunofluorescence, neuronal apoptosis, brain water content, and neurological score analyses. We found pronounced TBI-induced downregulation of WNK3 expression and upregulation of NKCC1 expression in neurons, especially at 48 h. Overexpression of WNK3 significantly ameliorated neuronal apoptosis, blood-brain barrier (BBB) disruption, brain edema and neurological deficits at 48 h after TBI. These effects were concomitant with reductions in p-NKCC1 and phosphorylated extracellular signal-regulated kinase (p-ERK1/2) expression. Furthermore, bumetanide administration enhanced the neuroprotective effects of WNK3 overexpression against brain injury. Thus, WNK3 plays a neuroprotective role in TBI, and overexpression of WNK3 may increase cell resistance to apoptotic insults and brain edema, thereby alleviating secondary brain injury.

MEL Ameliorates Post-SAH Cerebral Vasospasm by Affecting the Expression of eNOS and HIF1α via H19/miR-138/eNOS/NO and H19/miR-675/HIF1α

Melatonin (MEL) has been demonstrated to exert a protective effect against subarachnoid hemorrhage (SAH), and nitric oxide (NO) has been shown to play an important role in the pathogenesis of vasospasm. This study aims to explore the underlying molecular mechanisms of MEL in the control of vasospasm following SAH. MEL administration attenuates SAH-induced vasospasm and neurobehavioral deficits. Expressions of H19, eNOS, and miR-675 are low in the SAH group, while expressions of miR-138 and HIF1α are high in the SAH group. Also, MEL treatment upon SAH rats completely restores the dysregulation of H19, eNOS, miR-675, miR-138, and HIF1α to their normal levels. Moreover, MEL dose dependently increases the luciferase activity of H19 promoter and hence the expression of H19. Additionally, H19 directly targets miR-675 and miR-138 to increase miR-675 expression and inhibit miR-138 expression. As virtual target genes of miR-675 and miR-138, respectively, HIF1α and eNOS are also regulated by the treatment with MEL. In particular, MEL treatment increases the expression of miR-675 and eNOS level while decreasing the expression of miR-138 and HIF1α in a dose dependent manner. Our study found that MEL ameliorates post-SAH vasospasm by regulating the expression of eNOS and HIF1α via the H19/miR-138/eNOS/NO and H19/miR-675/HIF1α signaling pathways.

Neuroprotection mediated by the Wnt/Frizzled signaling pathway in early brain injury induced by subarachnoid hemorrhage

The Wnt/Frizzled signaling pathway participates in many inflammation-linked diseases. However, the inflammatory response mediated by the Wnt/Frizzled signaling pathway in experimental subarachnoid hemorrhage has not been thoroughly investigated. Consequently, in this study, we examined the potential role of the Wnt/Frizzled signaling pathway in early brain injury in rat models of subarachnoid hemorrhage. Simultaneously, possible neuroprotective mechanisms were also investigated. Experimental subarachnoid hemorrhage rat models were induced by injecting autologous blood into the prechiasmatic cistern. Experiment 1 was designed to examine expression of the Wnt/Frizzled signaling pathway in early brain injury induced by subarachnoid hemorrhage. In total, 42 adult rats were divided into sham (injection of equivalent volume of saline), 6-, 12-, 24-, 48-, 72-hour, and 1-week subarachnoid hemorrhage groups. Experiment 2 was designed to examine neuroprotective mechanisms of the Wnt/Frizzled signaling pathway in early brain injury induced by subarachnoid hemorrhage. Rats were treated with recombinant human Wnt1 (rhwnt1), small interfering Wnt1 (siwnt1) RNA, and monoclonal antibody of Frizzled1 (anti-Frizzled1) at 48 hours after subarachnoid hemorrhage. Expression levels of Wnt1, Frizzled1, β-catenin, peroxisome proliferator-activated receptor-γ, CD36, and active nuclear factor-κB were examined by western blot assay and immunofluorescence staining. Microglia type conversion and inflammatory cytokine levels in brain tissue were examined by immunofluorescence staining and enzyme-linked immunosorbent assay. Our results show that compared with the sham group, expression levels of Wnt1, Frizzled1, and β-catenin were low and reduced to a minimum at 48 hours, gradually returning to baseline at 1 week after subarachnoid hemorrhage. rhwnt1 treatment markedly increased Wnt1 expression and alleviated subarachnoid hemorrhage-induced early brain injury (within 72 hours), including cortical cell apoptosis, brain edema, and neurobehavioral deficits, accompanied by increasing protein levels of β-catenin, CD36, and peroxisome proliferator-activated receptor-γ and decreasing protein levels of nuclear factor-κB. Of note, rhwnt1 promoted M2-type microglia conversion and inhibited release of inflammatory cytokines (interleukin-1β, interleukin-6, and tumor necrosis factor-α). In contrast, siwnt1 RNA and anti-Frizzled1 treatment both resulted in an opposite effect. In conclusion, the Wnt/Frizzled1 signaling pathway may participate in subarachnoid hemorrhage-induced early brain injury via inhibiting the inflammatory response, including regulating microglia type conversion and decreasing inflammatory cytokine release. The study was approved by the Animal Ethics Committee of Anhui Medical University and First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China (approval No. LLSC-20180202) in May 2017.

Aloperine activates the Nrf2-ARE pathway when ameliorating early brain injury in a subarachnoid hemorrhage model

Aloperine (ALO) exhibits neuroprotective effects against oxidative stress in vitro; however, its protective effect in early brain injury (EBI) following experimental subarachnoid hemorrhage (SAH) remains to be elucidated. The aim of the current study was to evaluate the antioxidant activity of ALO in EBI, and its association with nuclear factor erythroid-related factor 2 and the antioxidant responsive element (Nrf2-ARE) survival pathway. In the present study, an experimental SAH model was induced in rats following a prechiasmatic cistern injection. All rats were randomly divided into five groups: Sham, SAH, SAH+ vehicle, and an SAH+ ALO group (including low and high doses). ALO was administrated intraperitoneally at 2 and 24 h following induction of the SAH model. Brain samples were collected from each group at 48 h after SAH induction. Subsequently, western blotting, immunohistochemistry and cell apoptosis assays were performed, along with assessments for brain edema, neurological deficit, and the activity of oxidant/antioxidant factors. It was observed that the expression of Nrf2-ARE pathway-associated agents, including Nrf2, and heme oxygenase-1, were markedly increased in the high concentration ALO group compared with that of the SAH group. In addition, the level of oxidative damage was reduced. Furthermore, early brain damage, including brain edema, neurological deficit and cellular apoptosis were significantly ameliorated. In conclusion, the results of the present study indicate that ALO can ameliorate oxidative damage against EBI following SAH, most likely via the Nrf2-ARE survival pathway.

Akt Specific Activator SC79 Protects against Early Brain Injury following Subarachnoid Hemorrhage

A growing body of evidence demonstrates that Akt may serve as a therapeutic target for treatment of early brain injury following subarachnoid hemorrhage (SAH). The purpose of the current study was to evaluate the neuroprotective effect of Akt specific activator SC79 in an experimental rat model of SAH. SAH was induced by injecting 300 μL of blood into the prechiasmatic cistern. Intracerebroventricular (ICV) injection of SC79 (30 min post-SAH) induced the p-Akt (Ser473) expression in a dose-dependent manner. A single ICV dose treatment of SC79 (100 μg/rat) significantly increased the expression of Bcl-2 and p-GSK-3β (Ser9), decreased the protein levels of Bax, cytoplasm cytochrome c, and cleaved caspase-3, indicating the antiapoptotic effect of SC79. As a result, the number of apoptotic cells was reduced 24 h post SAH. Moreover, SC79 treatment alleviated SAH-induced oxidative stress, restored mitochondrial morphology, and improved neurological deficits. Strikingly, treatment of SC79 provided a beneficial outcome against neurologic deficit with a therapeutic window of at least 4 h post SAH by ICV injection and 30 min post SAH by intraperitoneal injection. Collectively, SC79 exerts its neuroprotective effect likely through the dual activities of antioxidation and antiapoptosis. These data provide a basic platform to consider SC79 as a novel therapeutic agent for treatment of SAH.

Molecular mechanisms and cell signaling of 20-hydroxyeicosatetraenoic acid in vascular pathophysiology

Cytochrome P450s enzymes catalyze the metabolism of arachidonic acid to epoxyeicosatrienoic acids (EETs), dihydroxyeicosatetraenoic acid and hydroxyeicosatetraeonic acid (HETEs). 20-HETE is a vasoconstrictor that depolarizes vascular smooth muscle cells by blocking K+ channels. EETs serve as endothelial derived hyperpolarizing factors. Inhibition of the formation of 20-HETE impairs the myogenic response and autoregulation of renal and cerebral blood flow. Changes in the formation of EETs and 20-HETE have been reported in hypertension and drugs that target these pathways alter blood pressure in animal models. Sequence variants in CYP4A11 and CYP4F2 that produce 20-HETE, UDP-glucuronosyl transferase involved in the biotransformation of 20-HETE and soluble epoxide hydrolase that inactivates EETs are associated with hypertension in human studies. 20-HETE contributes to the regulation of vascular hypertrophy, restenosis, angiogenesis and inflammation. It also promotes endothelial dysfunction and contributes to cerebral vasospasm and ischemia-reperfusion injury in the brain, kidney and heart. This review will focus on the role of 20-HETE in vascular dysfunction, inflammation, ischemic and hemorrhagic stroke and cardiac and renal ischemia reperfusion injury.

Rutin Inhibits Neuroinflammation and Provides Neuroprotection in an Experimental Rat Model of Subarachnoid Hemorrhage, Possibly Through Suppressing the RAGE-NF-κB Inflammatory Signaling Pathway

As is known to all, neuroinflammation plays a vital role in early brain injury pathogenesis following subarachnoid hemorrhage (SAH). It has been shown that rutin have a property of inhibiting inflammation in many kinds of animal models. However, the effect of rutin on neuroinflammation after SAH remains uninvestigated. In this study, we investigated the potential effects of rutin on neuroinflammation and the underlying mechanism in an experimental rat model of SAH performed by endovascular perforation. Adult male SD rats were randomly divided into three groups, including sham group, SAH + vehicle group and SAH + rutin group (50 mg/kg) intraperitoneally (i.p.) administered at 30 min after SAH. After sacrificed at 24 h after SAH, all rats were examined by following tests, including neurologic scores, blood-brain barrier permeability, brain water content and neuronal cell death in cerebral cortex. The level of inflammation in brain was estimated by means of multiple molecules, including RAGE, NF-κB, and inflammation cytokines. Our results indicated that rutin could significantly downregulate the increased level of REGE, NF-κB and inflammatory cytokines in protein level. In addition, rutin could also ameliorate a series of secondary brain injuries such as brain edema, destruction of blood-brain barrier, neurological deficits and neuronal death. This study indicated that rutin administration had a neuroprotective effect in an experimental rat model of SAH, possibly through inhibiting RAGE-NF-κB mediated inflammation signaling pathway.

Decreased progranulin levels in patients and rats with subarachnoid hemorrhage: a potential role in inhibiting inflammation by suppressing neutrophil recruitment

Background

Subarachnoid hemorrhage (SAH) is a devastating neurological injury with high morbidity and mortality that is mainly caused by early brain injury (EBI). Progranulin (PGRN) is known to be involved in various biological functions, such as anti-inflammation and tissue repair. This study aimed to investigate the change of PGRN in the brain after SAH and its role on EBI.

Methods

The levels of PGRN, myeloperoxidase (MPO), interleukin1β (IL-1β), and tumor necrosis factor-α (TNF-α) were detected in the cerebrospinal fluid (CSF) from SAH patients by enzyme-linked immunosorbent assay (ELISA). In addition, PGRN levels were also detected in the cerebral cortex after experimental SAH in rats by western blotting and immunohistochemistry (IHC). Recombinant human PGRN (r-PGRN) or an equal volume of phosphate-buffered saline (PBS) was administrated at 30 min after SAH. All rats were subsequently sacrificed at 24 h after SAH. Neurological score and brain water content were assessed. For mechanistic studies, the changes of MPO, matrix metalloproteinase-9 (MMP-9), zonula occludens 1 (ZO-1), Bcl-2, and cleaved caspase-3 were examined by western blotting and the levels of pro-inflammatory cytokines (IL-1β and TNF-α) were determined by ELISA. In addition, neuronal apoptosis and blood brain barrier (BBB) permeability were examined.

Results

The levels of PGRN significantly decreased, and the levels of MPO, IL-1β, and TNF-α were markedly elevated in the CSF from SAH patients. In rats, PGRN levels in the brain also decreased after SAH. Administration of r-PGRN decreased brain water content and improved neurological scores at 24 h after SAH. These changes were associated with marked reductions in MPO, MMP-9, and proinflammation cytokine levels, as well as increased levels of Bcl-2 and ZO-1. In addition, neuronal apoptosis and BBB permeability were alleviated by r-PGRN.

Conclusions

These results indicate that the levels of PGRN decreased after SAH and that r-PGRN alleviates EBI after SAH possibly via inhibition of neutrophil recruitment, providing a new target for the treatment of SAH.

Fisetin alleviates early brain injury following experimental subarachnoid hemorrhage in rats possibly by suppressing TLR 4/NF-κB signaling pathway

Early brain injury (EBI) determines the unfavorable outcomes after subarachnoid hemorrhage (SAH). Fisetin, a natural flavonoid, has anti-inflammatory and neuroprotection properties in several brain injury models, but the role of fisetin on EBI following SAH remains unknown. Our study aimed to explore the effects of fisetin on EBI after SAH in rats. Adult male Sprague-Dawley rats were randomly divided into the sham and SAH groups, fisetin (25mg/kg or 50mg/kg) or equal volume of vehicle was given at 30min after SAH. Neurological scores and brain edema were assayed. The protein expression of toll-like receptor 4 (TLR 4), p65, ZO-1 and bcl-2 was examined by Western blot. TLR 4 and p65 were also assessed by immunohistochemistry (IHC). Enzyme-linked immunosorbent assay (ELISA) was performed to detect the production of pro-inflammatory cytokines. Terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling (TUNEL) was perform to assess neural cell apoptosis. High-dose (50mg/kg) fisetin significantly improved neurological function and reduced brain edema at both 24h and 72h after SAH. Remarkable reductions of TLR 4 expression and nuclear factor κB (NF-κB) translocation to nucleus were detected after fisetin treatment. In addition, fisetin significantly reduced the productions of pro-inflammatory cytokines, decreased neural cell apoptosis and increased the protein expression of ZO-1 and bcl-2. Our data provides the evidence for the first time that fisetin plays a protective role in EBI following SAH possibly by suppressing TLR 4/NF-κB mediated inflammatory pathway.

Role of Neurexin-1β and Neuroligin-1 in Cognitive Dysfunction After Subarachnoid Hemorrhage in Rats

Supplemental Digital Content is available in the text.

Neurexin-1β and neuroligin-1 play an important role in the formation, maintenance, and regulation of synaptic structures. This study is to estimate the potential role of neurexin-1β and neuroligin-1 in subarachnoid hemorrhage (SAH)-induced cognitive dysfunction.

TGFβ-activated Kinase 1 (TAK1) Inhibition by 5Z-7-Oxozeaenol Attenuates Early Brain Injury after Experimental Subarachnoid Hemorrhage

Accumulating evidence suggests that activation of mitogen-activated protein kinases (MAPKs) and nuclear factor NF-κB exacerbates early brain injury (EBI) following subarachnoid hemorrhage (SAH) by provoking proapoptotic and proinflammatory cellular signaling. Here we evaluate the role of TGFβ-activated kinase 1 (TAK1), a critical regulator of the NF-κB and MAPK pathways, in early brain injury following SAH. Although the expression level of TAK1 did not present significant alternation in the basal temporal lobe after SAH, the expression of phosphorylated TAK1 (Thr-187, p-TAK1) showed a substantial increase 24 h post-SAH. Intracerebroventricular injection of a selective TAK1 inhibitor (10 min post-SAH), 5Z-7-oxozeaenol (OZ), significantly reduced the levels of TAK1 and p-TAK1 at 24 h post-SAH. Involvement of MAPKs and NF-κB signaling pathways was revealed that OZ inhibited SAH-induced phosphorylation of p38 and JNK, the nuclear translocation of NF-κB p65, and degradation of IκBα. Furthermore, OZ administration diminished the SAH-induced apoptosis and EBI. As a result, neurological deficits caused by SAH were reversed. Our findings suggest that TAK1 inhibition confers marked neuroprotection against EBI following SAH. Therefore, TAK1 might be a promising new molecular target for the treatment of SAH.

Tert-butylhydroquinone alleviates early brain injury and cognitive dysfunction after experimental subarachnoid hemorrhage: role of Keap1/Nrf2/ARE pathway

Tert-butylhydroquinone (tBHQ), an Nrf2 activator, has demonstrated neuroprotection against brain trauma and ischemic stroke in vivo. However, little work has been done with respect to its effect on early brain injury (EBI) after subarachnoid hemorrhage (SAH). At the same time, as an oral medication, it may have extensive clinical applications for the treatment of SAH-induced cognitive dysfunction. This study was undertaken to evaluate the influence of tBHQ on EBI, secondary deficits of learning and memory, and the Keap1/Nrf2/ARE pathway in a rat SAH model. SD rats were divided into four groups: (1) Control group (n=40); (2) SAH group (n=40); (3) SAH+vehicle group (n=40); and (4) SAH+tBHQ group (n=40). All SAH animals were subjected to injection of autologous blood into the prechiasmatic cistern once in 20 s. In SAH+tBHQ group, tBHQ was administered via oral gavage at a dose of 12.5 mg/kg at 2 h, 12 h, 24 h, and 36 h after SAH. In the first set of experiments, brain samples were extracted and evaluated 48 h after SAH. In the second set of experiments, changes in cognition and memory were investigated in a Morris water maze. Results shows that administration of tBHQ after SAH significantly ameliorated EBI-related problems, such as brain edema, blood-brain barrier (BBB) impairment, clinical behavior deficits, cortical apoptosis, and neurodegeneration. Learning deficits induced by SAH was markedly alleviated after tBHQ therapy. Treatment with tBHQ markedly up-regulated the expression of Keap1, Nrf2, HO-1, NQO1, and GSTα1 after SAH. In conclusion, the administration of tBHQ abated the development of EBI and cognitive dysfunction in this SAH model. Its action was probably mediated by activation of the Keap1/Nrf2/ARE pathway.

SIRT1 inhibition by sirtinol aggravates brain edema after experimental subarachnoid hemorrhage

Secondary brain injury following subarachnoid hemorrhage (SAH) is poorly understood. We utilized a rat model of SAH to investigate whether SIRT1 has a protective role against brain edema via the tumor suppressor protein p53 pathway. Experimental SAH was induced in adult male Sprague-Dawley rats by prechiasmatic cistern injection. Brain SIRT1 protein levels were examined in the sham controls and in rats 6, 12, 24, 48, and 72 hr after SAH induction. The SIRT1 inhibitor sirtinol was administered by intracerebroventricular infusion. Neurological functions, blood-brain barrier (BBB) disruption, and brain water content were assessed. Endothelial cell apoptosis, caspase 3 protein expression, p53 acetylation, and matrix metalloproteinase-9 (MMP-9) activity were examined. Compared with the control, SIRT1 protein expression increased remarkably, reaching a maximum at 24 hr after SAH. Sirtinol treatment significantly lowered SIRT1 expression, accompanied by deteriorated neurologic function, BBB disruption, brain edema, increased endothelial cell apoptosis, and increased MMP-9 gelatinase activity compared with the rats treated with vehicle only. Our results suggest that increased expression of endogenous SIRT1 may play a neuroprotective role against brain edema after SAH.

Protective effect of quercetin against oxidative stress and brain edema in an experimental rat model of subarachnoid hemorrhage

Quercetin has been demonstrated to play an important role in altering the progression of ischemic brain injuries and neurodegenerative diseases by protecting against oxidative stress. The effects of quercetin on brain damage after subarachnoid hemorrhage (SAH), however, have not been investigated. This study was designed to explore the effects of quercetin on oxidative stress and brain edema after experimental SAH using four equal groups (n = 16) of adult male Sprague-Dawley (SD) rats, including a sham group, an SAH + vehicle group, an SAH + quercetin10 group, and an SAH + quercetin50 group. The rat SAH model was induced by injection of 0.3 ml of non-heparinised arterial blood into the prechiasmatic cistern. In the SAH + quercetin10 and SAH + quercetin50 groups, doses of 10 mg/kg and 50 mg/kg quercetin, respectively, were directly administered by intraperitoneal injection at 30 min, 12 h, and 24 h after SAH induction. Cerebral tissue samples were extracted for enzymatic antioxidant determination, lipid peroxidation assay, caspase-3 activity and water content testing 48 h after SAH. Treatment with a high dose (50 mg/kg) of quercetin markedly enhanced the activities of copper/zinc superoxide dismutase (CuZn-SOD) and glutathione peroxidase (GSH-Px), and treatment with this dose significantly reduced the level of malondialdehyde (MDA). Caspase-3 and brain edema was ameliorated and neurobehavioral deficits improved in rats that received the high dose of quercetin. The findings suggest that the early administration of optimal dose of quercetin may ameliorate brain damage and provide neuroprotection in the SAH model, potentially by enhancing the activity of endogenous antioxidant enzymes and inhibiting free radical generation.

Tamoxifen as an effective neuroprotectant against early brain injury and learning deficits induced by subarachnoid hemorrhage: possible involvement of inflammatory signaling

Background

Tamoxifen, a selective estrogen receptor modulator, has successfully been used to treat several animal models of brain injury, but the underlying mechanisms remain unclear. This study was undertaken to evaluate the effect of tamoxifen on the toll-like receptor 4 (TLR4)- and nuclear factor-κB (NF-κB)-related inflammatory signaling pathway and secondary brain injury in rats after subarachnoid hemorrhage (SAH).

Methods

Adult male Sprague-Dawley rats were divided into four groups: (1) control group (n = 28); (2) SAH group (n = 28); (3) SAH + vehicle group (n = 28); and (4) SAH + tamoxifen group (n = 28). All SAH animals were subjected to injection of autologous blood into the prechiasmatic cistern once on day 0. In SAH + tamoxifen group, tamoxifen was administered intraperitoneally at a dose of 5 mg/kg at 2 h, 12 h, and 36 h after SAH. In the first set of experiments, brain samples were extracted and evaluated at 48 h after SAH. In the second set of experiments, the Morris water maze was used to investigate cognitive and memory changes.

Results

We found that treatment with tamoxifen markedly inhibited the protein expressions of TLR4, NF-κB and the downstream inflammatory agents, such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and intercellular adhesion molecule-1 (ICAM-1). Administration of tamoxifen following SAH significantly ameliorated the early brain injury (EBI), such as brain edema, blood-brain barrier (BBB) impairment, and clinical behavior scale. Learning deficits induced by SAH were markedly alleviated after tamoxifen treatment.

Conclusions

Post-SAH tamoxifen administration may attenuate TLR4/NF-kappaB-mediated inflammatory response in the rat brain and result in abatement of the development of EBI and cognitive dysfunction after SAH.

Hyperbaric oxygen for cerebral vasospasm and brain injury following subarachnoid hemorrhage

The impact of acute brain injury and delayed neurological deficits due to cerebral vasospasm (CVS) are major determinants of outcomes after subarachnoid hemorrhage (SAH). Although hyperbaric oxygen (HBO) had been used to treat patients with SAH, the supporting evidence and underlying mechanisms have not been systematically reviewed. In the present paper, the overview of studies of HBO for cerebral vasospasm is followed by a discussion of HBO molecular mechanisms involved in the protection against SAH-induced brain injury and even, as hypothesized, in attenuating vascular spasm alone. Faced with the paucity of information as to what degree HBO is capable of antagonizing vasospasm after SAH, the authors postulate that the major beneficial effects of HBO in SAH include a reduction of acute brain injury and combating brain damage caused by CVS. Consequently, authors reviewed the effects of HBO on SAH-induced hypoxic signaling and other mechanisms of neurovascular injury. Moreover, authors hypothesize that HBO administered after SAH may "precondition" the brain against the detrimental sequelae of vasospasm. In conclusion, the existing evidence speaks in favor of administering HBO in both acute and delayed phase after SAH; however, further studies are needed to understand the underlying mechanisms and to establish the optimal regimen of treatment.

Signal transduction in cerebral arteries after subarachnoid hemorrhage-a phosphoproteomic approach

After subarachnoid hemorrhage (SAH), pathologic changes in cerebral arteries contribute to delayed cerebral ischemia and poor outcome. We hypothesize such changes are triggered by early intracellular signals, targeting of which may prevent SAH-induced vasculopathy. We performed an unbiased quantitative analysis of early SAH-induced phosphorylations in cerebral arteries and evaluated identified signaling components as targets for prevention of delayed vasculopathy and ischemia. Labeled phosphopeptides from rat cerebral arteries were quantified by high-resolution tandem mass spectrometry. Selected SAH-induced phosphorylations were validated by immunoblotting and monitored over a 24-hour time course post SAH. Moreover, inhibition of key phosphoproteins was performed. Major SAH-induced phosphorylations were observed on focal adhesion complexes, extracellular regulated kinase 1/2 (ERK1/2), calcium calmodulin-dependent kinase II, signal transducer and activator of transcription (STAT3) and c-Jun, the latter two downstream of ERK1/2. Inhibition of ERK1/2 6-hour post SAH prevented increases in cerebrovascular constrictor receptors, matrix metalloprotease-9, wall thickness, and improved neurologic outcome. STAT3 inhibition partially mimicked these effects. The study shows that quantitative mass spectrometry is a strong approach to study in vivo vascular signaling. Moreover, it shows that targeting of ERK1/2 prevents delayed pathologic changes in cerebral arteries and improves outcome, and identifies SAH-induced signaling components downstream and upstream of ERK1/2.

Evidence that 20-HETE contributes to the development of acute and delayed cerebral vasospasm

Recent studies have indicated that arachidonic acid (AA) is metabolized by the cytochrome P450 4A (CYP4A) enzymes in cerebral arteries to produce 20-hydroxyeicosatetraenoic acid (20-HETE) and that this compound has effects on cerebral vascular tone that mimic those seen following subarachnoid hemorrhage (SAH). In this regard, 20-HETE is a potent constrictor of cerebral arteries that decreases the open state probability of Ca(2+)-activated K(+) channels through activation of protein kinase C (PKC). It increases the sensitivity of the contractile apparatus to Ca(2+) by activating PKC and rho kinase. The formation of 20-HETE is stimulated by angiotensin II (AII), endothelin, adenosine triphosphate (ATP) and serotonin, and inhibited by NO, CO and superoxide radicals. Inhibitors of the formation of 20-HETE block the myogenic response of cerebral arterioles to elevations in transmural pressure in vitro and autoregulation of cerebral blood flow (CBF) in vivo. 20-HETE also plays an important role in modulating the cerebral vascular responses to vasodilators (NO and CO) and vasoconstrictors (AII, endothelin, serotonin). Recent studies have indicated that the levels of 20-HETE in cerebrospinal fluid (CSF) increase in rats, dogs and human patients following SAH and that inhibitors of the synthesis of 20-HETE prevent the acute fall in CBF in rats and reverse delayed vasospasm in both dogs and rats. This review examines the evidence that an elevation in the production of 20-HETE contributes to the initial fall in CBF following SAH and the later development of delayed vasospasm.

Induction of autophagy by cystatin C: a potential mechanism for prevention of cerebral vasospasm after experimental subarachnoid hemorrhage

BACKGROUND

Studies have demonstrated that autophagy pathways are activated in the brain after experimental subarachnoid hemorrhage (SAH) and this may play a protective role in early brain injury. However, the contribution of autophagy in the pathogenesis of cerebral vasospasm (CVS) following SAH, and whether up-regulated autophagy may contribute to aggravate or release CVS, remain unknown. Cystatin C (CysC) is a cysteine protease inhibitor that induces autophagy under conditions of neuronal challenge. This study investigated the expression of autophagy proteins in the walls of basilar arteries (BA), and the effects of CysC on CVS and autophagy pathways following experimental SAH in rats.

METHODS

All SAH animals were subjected to injection of 0.3 mL fresh arterial, non-heparinized blood into the cisterna magna. Fifty rats were assigned randomly to five groups: control group (n = 10), SAH group (n = 10), SAH + vehicle group (n = 10), SAH + low dose of CysC group (n = 10), and SAH + high dose of CysC group (n = 10). We measured proteins by western blot analysis, CVS by H&E staining method, morphological changes by electron microscopy, and recorded neuro-behavior scores.

RESULTS

Microtubule-associated protein light chain-3, an autophagosome biomarker, and beclin-1, a Bcl-2-interacting protein required for autophagy, were significantly increased in the BA wall 48 h after SAH. In the CysC-handled group, the degree of CVS, measured as the inner BA perimeter and BA wall thickness, was significantly ameliorated in comparison with vehicle-treated SAH rats. This effect paralleled the intensity of autophagy in the BA wall induced by CysC.

CONCLUSIONS

These results suggest that the autophagy pathway is activated in the BA wall after SAH and CysC-induced autophagy may play a beneficial role in preventing SAH-induced CVS.

Genetics of cerebral vasospasm

Cerebral vasospasm (CV) is a major source of morbidity and mortality in aneurysmal subarachnoid hemorrhage (aSAH). It is thought that an inflammatory cascade initiated by extravasated blood products precipitates CV, disrupting vascular smooth muscle cell function of major cerebral arteries, leading to vasoconstriction. Mechanisms of CV and modes of therapy are an active area of research. Understanding the genetic basis of CV holds promise for the recognition and treatment for this devastating neurovascular event. In our review, we summarize the most recent research involving key areas within the genetics and vasospasm discussion: (1) Prognostic role of genetics—risk stratification based on gene sequencing, biomarkers, and polymorphisms; (2) Signaling pathways—pinpointing key inflammatory molecules responsible for downstream cellular signaling and altering these mediators to provide therapeutic benefit; and (3) Gene therapy and gene delivery—using viral vectors or novel protein delivery methods to overexpress protective genes in the vasospasm cascade.

Inflammation in subarachnoid hemorrhage and delayed deterioration associated with vasospasm: a review

Delayed deterioration associated with vasospasm (DDAV) after subarachnoid hemorrhage (SAH), (often called vasospasm) continues to be both a difficult entity to treat and a leading cause of morbidity in patients. Until recently, attention was focused on alleviating the vascular spasm. Recent evidence shows that vascular spasm may not account for all the morbidity of DDAV. There is renewed interest in looking for other potential targets for therapy. Inflammation has become a promising area of research for new treatments. This review explores the evidence that inflammation is a driver of DDAV by asking three questions: (1) If inflammation is important in the pathogenesis of the disease, what part or parts of the inflammatory response are involved? (2) When does inflammation occur in SAH? (3) In what compartment of the skull does the inflammation occur, the cerebrospinal fluid and meninges, the cerebral arteries, or the brain itself?

Expression of NR2B in different brain regions and effect of NR2B antagonism on learning deficits after experimental subarachnoid hemorrhage

Approximately 50% of patients who survived after aneurysmal subarachnoid hemorrhage (SAH) have cognitive or neurobehavioral dysfunction. The mechanisms are not known. NR2B, one of the subunits of N-methyl-d-aspartate (NMDA) receptors, has been proved to be an important factor for synapse function and behavior cognition. Experiment 1 aimed to investigate the timecourse of the NR2B expression in the cortex, hippocampus, and cerebellum after SAH in rats. In experiment 2, we assessed the effect of Ro 25-6981 (a specific NR2B antagonist) on regulation of learning deficits and behavioral activity following SAH. All SAH animals were subjected to injection of autologous blood into the prechiasmatic cistern once on day 0. NR2B was assessed by Western blot analysis and immunohistochemistry. Cognitive and memory changes were investigated in the Morris water maze. As a result, the expression of NR2B was decreased remarkably in SAH groups compared with the control group and the low ebb was on days 1-3. The immunohistochemical staining demonstrated expression of NR2B was present mainly in the neurons in all of the three different regions, such as the cortex, hippocampus, and cerebellum. After Ro 25-6981 intraperitoneal administration, learning deficits induced by SAH was markedly aggravated and clinical behavior scale was also significantly decreased. Our results suggest that NR2B expression is down-regulated in the brain after experimental SAH and NR2B antagonism resulted in augmentation of the development of cognitive dysfunction after SAH.

Melatonin activates the Nrf2-ARE pathway when it protects against early brain injury in a subarachnoid hemorrhage model

Melatonin has beneficial effects against early brain injury (EBI) by modulating cerebral oxidative stress after experimental subarachnoid hemorrhage (SAH); however, few investigations relate to the precise underlying molecular mechanisms. To date, the relation between melatonin and nuclear factor erythroid 2-related factor 2 and antioxidant responsive element (Nrf2-ARE) pathway has not been studied in SAH models. This study was undertaken to evaluate the influence of melatonin on Nrf2-ARE pathway in rats after SAH. Adult male SD rats were divided into four groups: (i) control group (n=18); (ii) SAH group (n=18); (iii) SAH+vehicle group (n=18); and (iv) SAH+melatonin group (n=18). The rat SAH model was induced by injection of 0.3mL fresh arterial, nonheparinized blood into the prechiasmatic cistern in 20s. In SAH+melatonin group, melatonin was administered i.p. at 150mg/kg at 2 and 24hr after the induction of SAH. Brain samples were extracted at 48hr after SAH. Treatment with melatonin markedly increased the expressions of Nrf2-ARE pathway-related agents, such as Nrf2, heme oxygenase-1, NAD(P)H:quinone oxidoreductase 1, and glutathione S-transferase α-1. Administration of melatonin following SAH significantly ameliorated EBI, including brain edema, blood-brain barrier (BBB) impairment, cortical apoptosis, and neurological deficits. In conclusion, post-SAH melatonin administration may attenuate EBI in this SAH model, possibly through activating Nrf2-ARE pathway and modulating cerebral oxidative stress by inducing antioxidant and detoxifying enzymes.

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.

Mammalian target of rapamycin (mTOR) inhibition reduces cerebral vasospasm following a subarachnoid hemorrhage injury in canines

Mammalian target of rapamycin (mTOR) pathway is a serine/threonine protein kinase that plays a vital role in regulating growth, proliferation, survival, and protein synthesis among cells. In the present study, we investigated the role of the mTOR pathway following subarachnoid hemorrhage brain injury--specifically investigating its ability to mediate the activation of cerebral vasospasm. Additionally, we investigated whether key signaling pathway molecules such as the mTOR, P70S6K1, and 4E-BP1 play a role in the process. Thirty dogs were randomly divided into 5 groups: sham, SAH (subarachnoid hemorrhage), SAH+DMSO (dimethyl sulfoxide), SAH+Rapamycin and SAH+AZD8055. An established canine double-hemorrhage model of SAH was used by injecting autologous arterial blood into the cisterna magna on days 0 and 2. Angiography was performed at days 0 and 7. Clinical behavior, histology, immunohistochemistry, and Western blot of mTOR, P70S6K1, 4E-BP1 and PCNA (proliferating cell nuclear antigen) in the basilar arteries were examined. In the SAH and SAH+DMSO groups, severe angiographic vasospasm was obtained (34.3±19.8%, 38.4±10.3) compared with that in Sham (93.9±5.0%) respectively. mTOR, P70S6K1, 4E-BP1 and PCNA increased in the sample of spastic basilar arteries (p<0.05). In the SAH+RAPA and SAH+AZD8055 groups, Rapamycin and AZD8055 attenuated angiographic vasospasm (62.3±15.9% and 65.2±10.3%) while improving appetite and activity scores (p<0.05) on days 5 through 7. Rapamycin and AZD8055 significantly reduced the level and expression of mTOR, P70S6K1, 4E-BP1 and PCNA (p<0.05). In conclusion, our study suggests that the mTOR molecular signaling pathway plays a significant role in cerebral vasospasm following SAH, and that inhibition of the mTOR pathway has the potential to become an attractive strategy to treat vasospasm following SAH.

Role of autophagy in early brain injury after experimental subarachnoid hemorrhage

Autophagy is a self-degradative process and it plays a housekeeping role in removing misfolded or aggregated proteins, clearing damaged organelles, and eliminating intracellular pathogens. Previous studies have demonstrated that autophagy pathway was activated in brain after experimental subarachnoid hemorrhage (SAH); however, the role of autophagy in the pathogenesis of early brain injury (EBI) following SAH remains unknown. Experiment 1 aimed to investigate the time-course of the autophagy in the cortex following SAH. In experiment 2, we chose the maximum time point of autophagy activation and assessed the effects of rapamycin (RAP, autophagy activator) and 3-methyladenine (3-MA, autophagy inhibitor) on regulation of EBI. All SAH animals were subjected to injection of 0.3 ml fresh arterial, nonheparinized blood into prechiasmatic cistern in 20 s. As a result, microtubule-associated protein light chain-3 (LC3), a biomarker of autophagosome, and beclin-1, a Bcl-2-interacting protein required for autophagy, were significantly increased at the early stage of SAH and their expressions peaked at 24 h after SAH. In RAP-treated group, the early brain damage such as brain edema, blood-brain barrier (BBB) impairment, cortical apoptosis, and clinical behavior scale was significantly ameliorated in comparison with vehicle-treated SAH rats. Conversely, 3-MA decreased expression of LC3 and beclin-1, increased the average value of brain edema and BBB disfunction, and aggravated neurological deficits. Our results suggest that autophagy pathway is activated in the brain after SAH and may play a beneficial role to EBI development.

Progesterone administration modulates cortical TLR4/NF-κB signaling pathway after subarachnoid hemorrhage in male rats

Our previous study concerning brain trauma has shown that progesterone could regulate toll-like receptor 4 (TLR4) and nuclear factor-kappa B (NF-κB) signaling pathway in the brain, which also has been proved to play important roles in early brain injury (EBI) after subarachnoid hemorrhage (SAH). The aim of the current study was to investigate whether progesterone administration modulated TLR4/NF-κB pathway signaling pathway in the brain at the early stage of SAH. All SAH animals were subjected to injection of 0.3  ml fresh arterial, non-heparinized blood into prechiasmatic cistern in 20 seconds. Male rats were given 0 or 16  mg/kg injections of progesterone at post-SAH hours 1, 6, and 24. Brain samples were extracted at 48  h after SAH. As a result, SAH could induce a strong up-regulation of TLR4, NF-κB, pro-inflammatory cytokines, MCP-1, and ICAM-1 in the cortex. Administration of progesterone following SAH could down-regulate the cortical levels of these agents related to TLR4/NF-κB signaling pathway. Post-SAH progesterone treatment significantly ameliorated the EBI, such as the clinical behavior scale, brain edema, and blood-brain barrier (BBB) impairment. It was concluded that post-SAH progesterone administration may attenuate TLR4/NF-κB signaling pathway in the rat brain following SAH.

Protection of minocycline on early brain injury after subarachnoid hemorrhage in rats

Minocycline has been shown to be neuroprotective in cerebral ischemia and in other models of brain injury. Our goal is to observe the protection of minocycline on EBI after SAH and the mechanism. 48 adult male SD rats were randomly divided into four groups: the sham-operated group, SAH group, vehicle group (SAH+normal sodium), and minocycline group (SAH+minocycline). The SAH model was induced by injecting 300 μl of autologous arterial blood into the prechiasmatic cistern. Expressions of MMP-9 in the hippocampus were examined at 24 h by western blot and zymography. Western blot and zymography showed that the expression of total and active MMP-9 increased dramatically at 24 h after SAH compared with that of the sham group (P<0.01). The clinical assessments got a lower score than that of the sham-operated group. After treated with minocycline, the expression of MMP-9 decreased significantly (P<0.01 vs. vehicle group), and the clinical assessments improved. We conclude that minocycline can protect EBI after SAH, which may be related to the mechanism of inhibiting the expression of MMP-9 in the hippocampus.

Mitogen-activated protein kinases in cerebral vasospasm after subarachnoid hemorrhage: a review

BACKGROUND

Mitogen-activated protein kinases (MAPKs) have been implicated in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage. The goal of this review is to bring together recent diverse data concerning the roles of MAPKs in cerebral vasospasm and to consider the future research.

METHOD

A review of publications in the National Library of Medicine and National Institutes of Health database was conducted in August 2009 using specific keyword search terms pertaining to subarachnoid hemorrhage and MAPKs.

FINDINGS

There are nine in vitro studies and 17 in vivo studies published. Most of previous studies used MAPK inhibitors or their upstream molecule inhibitors, and showed that MAPK inhibitions prevented vasospasm. The MAPK cascade appears to interact with other signaling molecules, and MAPK may be an important final common pathway for the signaling transduction during cerebral vasospasm. However, the mechanism by which MAPK causes sustained vascular smooth muscle contraction remains unclear. In addition, the role of endogenous MAPK inhibitors, MAPK phosphatases, has not been investigated in cerebral vasospasm.

CONCLUSIONS

The experimental data support the causative role of MAPK in cerebral vasospasm and warrant further research.

Hydrogen peroxide toxicity induces Ras signaling in human neuroblastoma SH-SY5Y cultured cells

It has been reported that overproduction of reactive oxygen species occurs after brain injury and mediates neuronal cells degeneration. In the present study, we examined the role of Ras signaling on hydrogen peroxide-induced neuronal cells degeneration in dopaminergic neuroblastoma SH-SY5Y cells. Hydrogen peroxide significantly reduced cell viability in SH-SY5Y cultured cells. An inhibitor of the enzyme that catalyzes the farnesylation of Ras proteins, FTI-277, and a competitive inhibitor of GTP-binding proteins, GDP-beta-S significantly decreased hydrogen peroxide-induced reduction in cell viability in SH-SY5Y cultured cells. The results of this study might indicate that a Ras-dependent signaling pathway plays a role in hydrogen peroxide-induced toxicity in neuronal cells.

Potential role of Ras in cerebral vasospasm after experimental subarachnoid hemorrhage in rabbits

Previous studies have demonstrated that mitogen-activated protein kinase (MAPK) is involved in the pathogenesis of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH). Ras, an upstream regulator of MAPK, may be activated following SAH. The aim of this study was to investigate the role of Ras in cerebral vasospasm in a rabbit model of SAH. We first investigated the time course of Ras and ERK1/2 activation in the basilar artery after SAH. Next, for the time point at which Ras was maximally activated, we assessed the effect of FTI-277 (a Ras farnesyltransferase inhibitor) on cerebral vasospasm. SAH was induced by injecting autologous blood into the cisterna magna on both day 0 and day 2. FTI-277 was injected into the cisterna magna every 24 hours, beginning 30 minutes after blood injection to the last day of the experiment. Elevated expression of Ras-GTP and phosphorylated ERK1/2 was detected in the basilar artery after SAH and expression peaked on day 3. FTI-277 administration resulted in lower Ras-GTP and phosphorylated ERK1/2 levels and markedly attenuated vasospasm in the basilar arteries relative to animals that did not receive FTI-277. Our results suggest that Ras protein is activated in the arterial wall after SAH and contributes to vasospasm development.

A yeast-based genomic strategy highlights the cell protein networks altered by FTase inhibitor peptidomimetics

Background

Farnesyltransferase inhibitors (FTIs) are anticancer agents developed to inhibit Ras oncoprotein activities. FTIs of different chemical structure act via a conserved mechanism in eukaryotic cells. They have low toxicity and are active on a wide range of tumors in cellular and animal models, independently of the Ras activation state. Their ultimate mechanism of action, however, remains undetermined. FTase has hundred of substrates in human cells, many of which play a pivotal role in either tumorigenesis or in pro-survival pathways. This lack of knowledge probably accounts for the failure of FTIs at clinical stage III for most of the malignancies treated, with the notable exception of haematological malignancies. Understanding which cellular pathways are the ultimate targets of FTIs in different tumor types and the basis of FTI resistance is required to improve the efficacy of FTIs in cancer treatment.

Results

Here we used a yeast-based cellular assay to define the transcriptional changes consequent to FTI peptidomimetic administration in conditions that do not substantially change Ras membrane/cytosol distribution. Yeast and cancer cell lines were used to validate the results of the network analysis. The transcriptome of yeast cells treated with FTase inhibitor I was compared with that of untreated cells and with an isogenic strain genetically inhibited for FTase activity (Δram1). Cells treated with GGTI-298 were analyzed in a parallel study to validate the specificity of the FTI response. Network analysis, based on gene ontology criteria, identified a cell cycle gene cluster up-regulated by FTI treatment that has the Aurora A kinase IPL1 and the checkpoint protein MAD2 as hubs. Moreover, TORC1-S6K-downstream effectors were found to be down-regulated in yeast and mammalian FTI-treated cells. Notably only FTIs, but not genetic inhibition of FTase, elicited up-regulation of ABC/transporters.

Conclusions

This work provides a view of how FTIs globally affect cell activity. It suggests that the chromosome segregation machinery and Aurora A association with the kinetochore as well as TORC1-S6K downstream effectors are among the ultimate targets affected by the transcriptional deregulation caused by FTI peptidomimetics. Moreover, it stresses the importance of monitoring the MDR response in patients treated with FTIs.

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.

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.

Matrix metalloproteinase-9 potentiates early brain injury after subarachnoid hemorrhage

OBJECTIVE

This study investigated the role of matrix metalloproteinase-9 (MMP-9) in early brain injury after subarachnoid hemorrhage (SAH).

METHOD

Sprague-Dawley male rats (n=36) weighing between 250 and 300 g were used. SAH was produced by injecting autologous arterial blood into the pre-chiasmatic cistern. MMP-9 protein expression and activity were measured by Western blot and zymogram; laminin expression and neuronal cell in hippocampus were studied by immunohistochemistry and TUNEL staining at 24 hours after SAH in the presence or absence of a selective MMP-9 inhibitor SB-3CT.

RESULT

MMP-9 was activated by SAH and inhibited by SB-3CT at 24 hours after SAH (p<0.01). Laminin, the substrate of MMP-9, was decreased at 24 hours after SAH, and SB-3CT prevented laminin degradation. The number of TUNEL-positive neurons in hippocampus was increased after SAH and decreased by SB-3CT (p<0.01). In addition, brain water content and neurological functional abnormalities were attenuated by SB-3CT.

CONCLUSION

MMP-9 may be involved in early brain injury through degradation of laminin and neuronal death, and inhibition of MMP-9 may be a potential direction for brain protection after SAH.

Magnetic resonance imaging detects and predicts early brain injury after subarachnoid hemorrhage in a canine experimental model

The canine double hemorrhage model is an established model to study cerebral vasospasm, the late sequelae of subarachnoid hemorrhage (SAH). The present study uses magnetic resonance imaging (MRI) to examine the recently reported early brain injury after SAH. Double hemorrhage SAH modeling was obtained by injecting 0.5 mL/kg of autologous arterial blood into the cisterna magna of five adult mongrel dogs on day 0 and day 2, followed by imaging at day 2 and day 7 using a 4.7-Tesla (T) scanner. White matter (WM) showed a remarkable increase in T2 values at day 2 which resolved by day 7, whereas gray matter (GM) T2 values did not resolve. The apparent diffusion coefficient (ADC) values progressively increased in both WM and GM after SAH, suggestive of a transition from vasogenic to cytotoxic edema. Ventricular volume also increased dramatically. Prominent neuronal injury with Nissl's staining was seen in the cortical GM and in the periventricular tissue. Multimodal MRI reveals acute changes in the brain after SAH and can be used to non-invasively study early brain injury and normal pressure hydrocephalus post-SAH. MR can also predict tissue histopathology and may be useful for assessing pharmacological treatments designed to ameliorate SAH.

Magnetic resonance imaging in the canine double-haemorrhage subarachnoid haemorrhage model

In this study, we investigated T2 weighted imaging (T2WI) and T2 values of the cortex, thalamus and cerebrospinal fluid (CSF) of the ventricles in the canine double-haemorrhage subarachnoid haemorrhage (DHSAH) model. T2 values in the cortex increased compared to prescan values from 123.07 +/- 18.72 msec on day 2 to 89.43 +/- 1.98 msec on day 7 (p < 0.05). A trend toward a temporal increase in T2 values was observed in the thalamus, but did not reach significance. The T2 values of the ventricular CSF increased by 102.2% on day 2 and 159.6% on day 7 compared to prescan values. These changes reached significance (p < 0.05) on day 7. Additionally, the ventricular size increased over the study period. Our data suggest that we can use this model to investigate acute brain injury and normal pressure hydrocephalus (NPH) after SAH.

Inhibition of c-Jun N-terminal kinase pathway attenuates cerebral vasospasm after experimental subarachnoid hemorrhage through the suppression of apoptosis

BACKGROUND

Recent studies have demonstrated that apoptosis in cerebral arteries could play an essential role in cerebral vasospasm after subarachnoid hemorrhage (SAH) and that SP600125, an inhibitor of c-Jun N-terminal kinase (JNK) could suppress apoptosis. The present study examined whether SP600125 could reduce cerebral vasospasm through the suppression of apoptosis.

METHOD

Fifteen dogs were assigned to 3 groups: control, SAH, and SAH + SP600125 (30 micromol/l). SAH was induced by the injection of autologous blood into the cisterna magna on day 0 and day 2. Angiograms were evaluated on day 0 and day 7. The activation of the JNK pathway and caspase-3 were also evaluated using Western blot. To determine the distribution, TUNEL staining and immunohistochemistry for phosphorylated c-jun and cleaved caspase-3 were performed.

FINDINGS

Severe vasospasm was observed in the basilar artery of the SAH dogs. SP600125 reduced angiographic and morphological vasospasm and reduced the expression of cleaved caspase-3, thereby suppressing apoptosis.

CONCLUSIONS

These results demonstrate that SP600125 attenuates cerebral vasospasm through the suppression of apoptosis, which may provide a novel therapeutic target for cerebral vasospasm.

Activation of c-jun in the rat basilar artery after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) initiates a series of cellular and molecular events, some of which involve a mitogen activated protein kinase, c-jun N-terminal kinase (JNK). However, precise details regarding activation of c-jun in the vessel wall after SAH largely remain to be elucidated. In this study, we therefore investigated the localization and time-dependent expression of c-jun in the rat basilar artery after SAH in a rat single-hemorrhage model featuring infusion of autologous arterial blood. Basilar arteries were obtained at 2, 6 and 12h and 1, 2, 4 and 7 days after SAH, as well as from controls. Western blot analysis with c-jun, phosphorylated c-jun at Ser(63), and actin antibodies revealed that c-jun was immediately phosphorylated at Ser(63) within 2h, thereafter gradually becoming dephosphorylated, while total c-jun and actin levels remained almost unchanged. Immunohistochemistry demonstrated phosphorylation of c-jun at Ser(63) to occur in smooth muscle cells of the basilar artery 2h after SAH. These results indicate that c-jun is activated in the basilar artery immediately after the onset of SAH, presumably resulting in transcription of immediate early genes and smooth muscle cell proliferation.

p53 may play an orchestrating role in apoptotic cell death after experimental subarachnoid hemorrhage

OBJECTIVE

Secondary brain injury after subarachnoid hemorrhage (SAH) is poorly understood. As a result, there are few treatment options. Consequently, SAH is associated with a high rate of morbidity and mortality. In an effort to combat these problems, the role of apoptosis was examined in the whole brain after SAH. In particular, the role of p53 and the three major apoptotic cascades were studied, the caspase-dependent and caspase-independent cascades and the mitochondrial pathway.

METHODS

In this study, 195 Sprague-Dawley rats were divided into three groups, including sham, nontreatment, and treatment (Pifithrin-alpha; BIOMOL, Inc., Plymouth Meeting, PA) groups. The monofilament puncture model was used to induce SAH and the animals were subsequently sacrificed at 24 and 72 hours. Western blot analysis, histology, physiological parameters, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling, and immunohistological techniques were used to demonstrate the role of p53 and the apoptotic cascades in the rat brain after SAH. In addition, outcome was determined based on mortality rates and neurological outcome scores.

RESULTS

We found that p53 and associated apoptotic proteins were up-regulated after SAH and that downstream mediators of apoptosis were negatively influenced by the inhibition of p53 by Pifithrin-alpha. Furthermore, we found that apoptotic inhibition resulted in less cell death and an overall favorable outcome in the treated animals.

CONCLUSION

These results suggest that apoptosis may be an important cause of cell death in the brain after SAH and that p53 may play an orchestrating role regarding apoptosis in SAH.

Hemoglobin, NO, and 20-HETE interactions in mediating cerebral vasoconstriction following SAH

Recent studies have indicated that 20-hydroxyeicosatetraenoic acid (20-HETE) contributes to the fall in cerebral blood flow (CBF) after subarachnoid hemorrhage (SAH), but the factors that stimulate the production of 20-HETE are unknown. This study examines the role of vasoactive factors released by clotting blood vs. the scavenging of nitric oxide (NO) by hemoglobin (Hb) in the fall in CBF after SAH. Intracisternal (icv) injection of blood produced a greater and more prolonged (120 vs. 30 min) decrease in CBF than that produced by a 4% solution of Hb. Pretreating rats with N(omega)-nitro-l-arginine methyl ester (l-NAME; 10 mg/kg iv) to block the synthesis of NO had no effect on the fall in CBF produced by an icv injection of blood. l-NAME enhanced rather than attenuated the fall in CBF produced by an icv injection of Hb. Blockade of the synthesis of 20-HETE with TS-011 (0.1 mg/kg iv) prevented the sustained fall in CBF produced by an icv injection of blood and the transient vasoconstrictor response to Hb. Hb (0.1%) reduced the diameter of the basilar artery (BA) of rats in vitro by 10 +/- 2%. This response was reversed by TS-011 (100 nM). Pretreatment of vessels with l-NAME (300 muM) reduced the diameter of BA and blocked the subsequent vasoconstrictor response to the addition of Hb to the bath. TS-011 returned the diameter of vessels exposed to l-NAME and Hb to that of control. These results suggest that the fall in CBF after SAH is largely due to the release of vasoactive factors by clotting blood rather than the scavenging of NO by Hb and that 20-HETE contributes the vasoconstrictor response of cerebral vessels to both Hb and blood.

Role of c-Jun N-Terminal Kinase in Cerebral Vasospasm After Experimental Subarachnoid Hemorrhage

Background and Purpose— Inflammation could play a role in cerebral vasospasm after subarachnoid hemorrhage (SAH). SP600125 a c-Jun N-terminal kinase (JNK) inhibitor reduces inflammation. The present study examined if SP600125 could reduce cerebral vasospasm.

Methods— Twenty-seven dogs were assigned to 5 groups: control, SAH, SAH plus dimethyl sulfoxide (DMSO), SAH plus SP600125 (10 μmol/L), and SAH plus SP600125 (30 μmol/L). SAH was induced by the injection of autologous blood into the cisterna magna on day 0 and day 2. Angiograms were evaluated on day 0 and day 7. The behavior of the dogs was evaluated daily. The activation of the JNK pathway, the infiltration of leukocytes, and the production of cytokines were also evaluated.

Results— Severe vasospasm was observed in the basilar artery of SAH and DMSO dogs. The JNK signaling pathway was activated in the basilar artery after SAH and SP600125 reduced angiographic and morphological vasospasm and improved behavior scores with a concomitant reduction of infiltrated leukocytes and IL-6 production.

Conclusions— These results demonstrate that SP600125 attenuated cerebral vasospasm through a suppressed inflammatory response, which may provide a novel therapeutic target for cerebral vasospasm.

Vascular smooth muscle function: The physiology and pathology of vasoconstriction

Vascular smooth muscle is the contractile component of arteries and veins. The control of contraction and relaxation is dependent upon intracellular and extracellular signals. Abnormal contractions can cause and or contribute to pathology such as hypertension, ischemia and infarction. In this review, we address the vascular pathogenesis associated with hypertension and subarachnoid hemorrhage induced cerebral vasospasm. Hypertension is a multifactorial disease with many causes and a profound impact on the cardiovascular system, whereas subarachnoid hemorrhage induced cerebral vasospasm is a pathological vasoconstriction often causing infarction that is thought to be 'caused' by a factor or factors in the CSF following the hemorrhage. However, the mechanism by which the vessels are constricted is unknown. Although the causes for these two pathological vasoconstrictions remain to be determined, we conclude that the common denominator is that these contractile changes result in pathology with devastating consequences to human health.

Reversal of delayed vasospasm by an inhibitor of the synthesis of 20-HETE

This study characterized the time course of changes in cerebral blood flow (CBF) and vascular diameter in a dual-hemorrhage model of subarachnoid hemorrhage (SAH) in rats and examined whether acute blockade of the synthesis of 20-hydroxyeicosatetraenoic acid (20-HETE) with N-(3-chloro-4-morpholin-4-yl)phenyl-N'-hydroxyimido formamide (TS-011) can reverse delayed vasospasm in this model. Rats received an intracisternal injection of blood (0.4 ml) on day 0 and a second injection 2 days later. CBF was sequentially measured using laser-Doppler flowmetry, and the diameters of the cerebral arteries were determined after filling the cerebral vasculature with a casting compound. CBF fell to 67% of control after the first intracisternal injection of blood but returned to a value near control 24 h later. CBF again fell to 63% of control after a second intracisternal injection of blood and remained 30% below control for 5 days. The fall in CBF after the second intracisternal injection of blood was associated with a sustained 30% reduction in the diameters of the middle cerebral, posterior communicating, and basilar arteries. Acute blockade of the synthesis of 20-HETE with TS-011 (0.1 mg/kg i.v.), 5 days after the second SAH, increased the diameters of the cerebral arteries, and CBF returned to control. These results indicate that the rats develop delayed vasospasm after induction of the dual-hemorrhage model of SAH and that blockade of the synthesis of 20-HETE fully reverses cerebral vasospasm in this model. They also implicate 20-HETE in the development and maintenance of delayed cerebral vasospasm.