Animal Models Of Subarachnoid Hemorrhage Research Articles

Methazolamide improves neurological behavior by inhibition of neuron apoptosis in subarachnoid hemorrhage mice.

Subarachnoid hemorrhage (SAH) results in significant nerve dysfunction, such as hemiplegia, mood disorders, cognitive and memory impairment. Currently, no clear measures can reduce brain nerve damage. The study of brain nerve protection after SAH is of great significance. We aim to evaluate the protective effects and the possible mechanism of methazolamide in C57BL/6J SAH animal model in vivo and in blood-induced primary cortical neuron (PCNs) cellular model of SAH in vitro. We demonstrate that methazolamide accelerates the recovery of neurological damage, effectively relieves cerebral edema, and improves cognitive function in SAH mice as well as offers neuroprotection in blood- or hemoglobin-treated PCNs and partially restores normal neuronal morphology. In addition, western blot analyses show obviously decreased expression of active caspase-3 in methazolamide-treated SAH mice comparing with vehicle-treated SAH animals. Furthermore, methazolamide effectively inhibits ROS production in PCNs induced by blood exposure or hemoglobin insult. However, methazolamide has no protective effects in morality, fluctuation of cerebral blood flow, SAH grade, and cerebral vasospasm of SAH mice. Given methazolamide, a potent carbonic anhydrase inhibitor, can penetrate the blood–brain barrier and has been used in clinic in the treatment of ocular conditions, it provides potential as a novel therapy for SAH.

Sulforaphane activates the cerebral vascular Nrf2–ARE pathway and suppresses inflammation to attenuate cerebral vasospasm in rat with subarachnoid hemorrhage

Nrf2–ARE pathway reportedly plays a protective role in several central nervous system diseases. No study has explored the role of the Nrf2–ARE pathway in cerebral vasospasm(CVS) after subarachnoid hemorrhage(SAH). The purpose of the present study was to investigate the activation of the cerebral vascular Nrf2–ARE pathway and to determine the potential role of this pathway in the development of CVS following SAH. We investigated whether the administration of sulforaphane (SFN, a specific Nrf2 activator) modulated vascular caliber, Nrf2-ARE pathway activity, proinflammatory cytokine expression, and clinical behavior in a rat model of SAH. A two-hemorrhage protocol was used to generate an animal model of SAH in male Sprague-Dawley rats. Administration of SFN to these rats following SAH enhanced the activity of the Nrf2-ARE pathway and suppressed the release of proinflammatory cytokines. Vasospasm was markedly attenuated in the basilar arteries after SFN therapy. Additionally, SFN administration significantly ameliorated two behavioral functions disrupted by SAH. These results suggest that SFN has a therapeutic benefit in post-SAH, and this may be due to elevated Nrf2-ARE pathway activity and inhibition of cerebral vascular proinflammatory cytokine expression.

C.02: Whole genome expression profiling of blood-brain barrier endothelial cells after experimental subarachnoid hemorrhage

Background: The pathophysiology of subarachnoid hemorrhage (SAH) is complex and includes disruption of the blood-brain barrier (BBB). We freshly isolated BBB endothelial cells (BECs) by 2 distinct methods after experimental SAH and then interrogated their gene expression profiles with the goal of uncovering new therapeutic targets. Methods: SAH was induced using the prechiasmatic blood injection mouse model. BBB permeability studies were performed by administering intraperitoneal cadaverine dye injections at 24h and 48h. BECs were isolated either by sequential magnetic-based sorting for CD45-CD31+ cells or by fluorescence-activated cell sorting (FACS) for Tie2+Pdgfrb- cells. Total RNA was extracted and analyzed using Affymetrix Mouse Gene 2.0 ST Arrays. Results: BBB impairment occurred at 24h and resolved by 48h after SAH. Analysis of gene expression patterns in BECs at 24h reveal clustering of SAH and sham samples. We identified 707 (2.8%) significant differentially-expressed genes (403 upregulated, 304 downregulated) out of 24,865 interrogated probe sets. Many significantly upregulated genes were involved in inflammatory pathways. These microarray results were validated with real-time polymerase chain reaction (RT-PCR). Conclusions: This study is the first to investigate in an unbiased manner, whole genome expression profiling of freshly-isolated BECs in an SAH animal model, yielding targets for novel therapeutic intervention.

Endovascular Perforation Murine Model of Subarachnoid Hemorrhage.

Subarachnoid hemorrhage (SAH) is a subtype of stroke with disastrous outcomes of high disability and mortality. A variety of endeavors have been developed to explore a SAH animal model for investigation of the disease. Among these models, the endovascular perforation SAH model was considered to be the most simulative to the clinical human SAH because it reproduces several pathophysiology procedures and presents some of the most important post-hemorrhage features. An applicable SAH animal model should have the characteristics of low mortality rate, limited surgical manipulation, and adaptation to many species, which permits reproducibility and standardization. An intensive discussion of how to improve the techniques and refine the procedure has taken place in the last decade. This report describes our experiences with a murine model of SAH. We aim to standardize and optimize the procedures to establish a relatively stable animal model for SAH research.

Functional response of cerebral blood flow induced by somatosensory stimulation in rats with subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) is often accompanied by cerebral vasospasm (CVS), which is the phenomenon of narrowing of large cerebral arteries, and then can produce delayed ischemic neurological deficit (DIND) such as lateralized sensory dysfunction. CVS was regarded as a major contributor to DIND in patients with SAH. However, therapy for preventing vasospasm after SAH to improve the outcomes may not work all the time. It is important to find answers to the relationship between CVS and DIND after SAH. How local cerebral blood flow (CBF) is regulated during functional activation after SAH still remains poorly understood, whereas, the regulation of CBF may play an important role in weakening the impact of CVS on cortex function. Therefore, it is worthwhile to evaluate the functional response of CBF in the activated cortex in an SAH animal model. Most evaluation of the effect of SAH is presently carried out by neurological behavioral scales. The functional imaging of cortical activation during sensory stimulation may help to reflect the function of the somatosensory cortex more locally than the behavioral scales do. We investigated the functional response of CBF in the somatosensory cortex induced by an electrical stimulation to contralateral forepaw via laser speckle imaging in a rat SAH model. Nineteen Sprague-Dawley rats from two groups (control group, n=10 and SAH group, n=9) were studied. SAH was induced in rats by double injection of autologous blood into the cisterna magna after CSF aspiration. The same surgical procedure was applied in the control group without CSF aspiration or blood injection. Significant CVS was found in the SAH group. Meanwhile, we observed a delayed peak of CBF response in rats with SAH compared with those in the control group, whereas no significant difference was found in magnitude, duration, and areas under curve of relative CBF changes between the two groups. The results suggest that the regulation function of local CBF during functional activation induced by somatosensory stimulation might not be seriously impaired in the somatosensory cortex of rats with SAH. Therefore, our findings might help to understand the clinical phenomenon that DIND might not occur even when CVS was found in SAH patients.

Role of Mitochondrial Calcium Uniporter in Early Brain Injury After Experimental Subarachnoid Hemorrhage.

Previous studies have shown that mitochondrial Ca(2+) is undertaken by mitochondrial calcium uniporter (MCU), and its accumulation is associated with the development of many diseases. However, little was known about the role of MCU in early brain injury (EBI) after subarachnoid hemorrhage (SAH). MCU can be opened by spermine under a physiological condition and inhibited by ruthenium red (RR). Herein, we investigated the effects of RR and spermine to reveal the role of MCU in SAH animal model. The data obtained with biochemical and histological assays showed that mitochondrial Ca(2+) concentration was significantly increased in the temporal cortex of rats 1, 2, and 3 days after SAH, consistent with constant high levels of cellular Ca(2+) concentration. In agreement with the observation in the acute phase, SAH rats showed an obvious increase of reactive oxygen species (ROS) level and decrease of ATP production. Blockage of MCU prevented Ca(2+) accumulation, abated the level of oxidative stress, and improved the energy supply. Translocation of cytochrome c, increased cleaved caspase-3, and a large amount of apoptotic cells after SAH were reversed by RR administration. Surprisingly, exogenous spermine did not increase cellular Ca(2+) concentration, but lessened the Ca(2+) accumulation after SAH to benefit the rats. Taken together, our results demonstrated that blockage of MCU or prevention of Ca(2+) accumulation after SAH is essential in EBI after SAH. These findings suggest that MCU is considered to be a therapeutic target for patients suffering from SAH.

Alteration of basilar artery rho-kinase and soluble guanylyl cyclase protein expression in a rat model of cerebral vasospasm following subarachnoid hemorrhage.

Background and Purpose. The vasoconstrictor endothelin-1 (ET-1) has been implicated in the pathogenesis of cerebral vasospasm following subarachnoid hemorrhage (SAH). Previous results showed that CGS 26303, an endothelin converting enzyme (ECE) inhibitor, effectively prevented and reversed arterial narrowing in animal models of SAH. In the present study, we assessed the effect of CGS 26303 on neurological deficits in SAH rats. The involvement of vasoactive pathways downstream of ET-1 signaling in SAH was also investigated. Methods. Sprague-Dawley rats were divided into five groups (n = 6/group): (1) normal control, (2) SAH, (3) SAH+vehicle, (4) SAH+CGS 26303 (prevention), and (5) SAH+CGS 26303 (reversal). SAH was induced by injecting autologous blood into cisterna magna. CGS 26303 (10 mg/kg) was injected intravenously at 1 and 24 hr after the initiation of SAH in the prevention and reversal protocols, respectively. Behavioral changes were assessed at 48 hr after SAH. Protein expression was analyzed by Western blots. Results. Deficits in motor function were obvious in the SAH rats, and CGS 26303 significantly improved the rate of paraplegia. Expressions of rho-kinase-II and membrane-bound protein kinase C-δ and rhoA were significantly increased, while those of soluble guanylyl cyclase α 1 and β 1 as well as protein kinase G were significantly decreased in the basilar artery of SAH rats. Treatment with CGS 26303 nearly normalized these effects. Conclusions. These results demonstrate that the rhoA/rho-kinase and sGC/cGMP/PKG pathways play pivotal roles in cerebral vasospasm after SAH. It also shows that ECE inhibition is an effective strategy for the treatment of this disease.

Genetic Elimination of eNOS Reduces Secondary Complications of Experimental Subarachnoid Hemorrhage

Delayed complications of subarachnoid hemorrhage (SAH) such as angiographic vasospasm, cortical spreading ischemia, microcirculatory dysfunction, and microthrombosis are reported in both patients and animal models of SAH. We demonstrated previously that SAH is associated with increased oxidative stress in the brain parenchyma, and that this correlates with dysfunction of endothelial nitric oxide synthase (eNOS) (homodimeric uncoupling). Uncoupling of eNOS exacerbated oxidative stress and enhanced nitric oxide (NO) depletion, and was associated with multiple secondary complications such as microthrombosis, neuronal apoptosis, and release of reactive oxygen species. Thus, we hypothesized that genetic abbrogation of eNOS would confer a beneficial effect on the brain after SAH. Using a prechiasmatic injection model of SAH, we show here that eNOS knockout (KO) significantly alleviates vasospasm of the middle cerebral artery and reduces superoxide production. Endothelial nitric oxide synthase KO also affected other nitric oxide synthase isoforms. It significantly increases neuron nitric oxide synthase expression but has no effect on inducible nitric oxide synthase. Endothelial nitric oxide synthase KO decreases Zn(2+) release after SAH, reduces microthrombi formation, and prevent neuronal degeneration. This work is consistent with our findings where, after SAH, increased oxidative stress can uncouple eNOS via Zn(2+) thiolate oxidation, or theoretically by depletion or oxidation of tetrahydrobiopterin, resulting in a paradoxical release of superoxide anion radical, further exacerbating oxidative stress and microvascular damage.

A Low Mortality Rat Model to Assess Delayed Cerebral Vasospasm After Experimental Subarachnoid Hemorrhage

Objective: To characterize and establish a reproducible model that demonstrates delayed cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) in rats, in order to identify the initiating events, pathophysiological changes and potential targets for treatment. Methods: Twenty-eight male Sprague-Dawley rats (250 - 300 g) were arbitrarily assigned to one of two groups - SAH or saline control. Rat subarachnoid hemorrhage in the SAH group (n=15) was induced by double injection of autologous blood, 48 hr apart, into the cisterna magna. Similarly, normal saline (n=13) was injected into the cisterna magna of the saline control group. Rats were sacrificed on day five after the second blood injection and the brains were preserved for histological analysis. The degree of vasospasm was measured using sections of the basilar artery, by measuring the internal luminal cross sectional area using NIH Image-J software. The significance was tested using Tukey/Kramer's statistical analysis. Results: After analysis of histological sections, basilar artery luminal cross sectional area were smaller in the SAH than in the saline group, consistent with cerebral vasospasm in the former group. In the SAH group, basilar artery internal area (.056 μm ± 3) were significantly smaller from vasospasm five days after the second blood injection (seven days after the initial blood injection), compared to the saline control group with internal area (.069 ± 3; p=0.004). There were no mortalities from cerebral vasospasm. Conclusion: The rat double SAH model induces a mild, survivable, basilar artery vasospasm that can be used to study the pathophysiological mechanisms of cerebral vasospasm in a small animal model. A low and acceptable mortality rate is a significant criterion to be satisfied for an ideal SAH animal model so that the mechanisms of vasospasm can be elucidated 7, 8. Further modifications of the model can be made to adjust for increased severity of vasospasm and neurological exams.

A Low Mortality Rat Model to Assess Delayed Cerebral Vasospasm After Experimental Subarachnoid Hemorrhage

To characterize and establish a reproducible model that demonstrates delayed cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) in rats, in order to identify the initiating events, pathophysiological changes and potential targets for treatment. Twenty-eight male Sprague-Dawley rats (250 - 300 g) were arbitrarily assigned to one of two groups - SAH or saline control. Rat subarachnoid hemorrhage in the SAH group (n=15) was induced by double injection of autologous blood, 48 hr apart, into the cisterna magna. Similarly, normal saline (n=13) was injected into the cisterna magna of the saline control group. Rats were sacrificed on day five after the second blood injection and the brains were preserved for histological analysis. The degree of vasospasm was measured using sections of the basilar artery, by measuring the internal luminal cross sectional area using NIH Image-J software. The significance was tested using Tukey/Kramer's statistical analysis. After analysis of histological sections, basilar artery luminal cross sectional area were smaller in the SAH than in the saline group, consistent with cerebral vasospasm in the former group. In the SAH group, basilar artery internal area (.056 μm ± 3) were significantly smaller from vasospasm five days after the second blood injection (seven days after the initial blood injection), compared to the saline control group with internal area (.069 ± 3; p=0.004). There were no mortalities from cerebral vasospasm. The rat double SAH model induces a mild, survivable, basilar artery vasospasm that can be used to study the pathophysiological mechanisms of cerebral vasospasm in a small animal model. A low and acceptable mortality rate is a significant criterion to be satisfied for an ideal SAH animal model so that the mechanisms of vasospasm can be elucidated. Further modifications of the model can be made to adjust for increased severity of vasospasm and neurological exams.

Inhibition of c-Jun N-terminal kinase prevents blood–brain barrier disruption and normalizes the expression of tight junction proteins clautin-5 and ZO-1 in a rat model of subarachnoid hemorrhage

The c-Jun N-terminal kinase (JNK) proteins are encoded by three genes (JNK1, JNK2, and JNK3), giving rise to multiple isoforms via alternative splicing. JNK inhibition using a chemical inhibitor SP600125 confers neuroprotection in an animal model of subarachnoid hemorrhage (SAH). The aim of this study is to investigate whether the protective effects of SP600125 were associated with modulation of tight junction proteins including claudin-5 and ZO-1 and to define which JNK isoforms were involved in the early brain injury after SAH. Seventy-five male Sprague Dawley rats (weighing 300-350g) were randomly assigned to five groups (n = 15): (1) sham, (2) SAH, (3) SAH + DMSO (dimethyl sulfoxide), (4) SAH + 10mg/kg SP600125, and (5) SAH + 30mg/kg SP600125. SP600125 or DMSO was injected intraperitoneally 1 h before and 6h after the induction of SAH. Animals from all the groups were killed 24h after SAH, and brain tissues were dissected and subjected to electron microscopic examination, Western blot analysis, and histological evaluation. SP600125 pretreatment restored tight junctions and attenuated blood-brain barrier (BBB) disruption and cerebral edema after SAH, coupled with reduced apoptosis in the cerebral cortex. SP600125 exposure restored the reduced expression of both claudin-5 and ZO-1 following SAH and normalized the levels of JNK1 and JNK3. Our data demonstrate that the JNK signaling plays an important role in the regulation of tight junction proteins and BBB integrity, and thus represents a promising target against brain injuries after SAH.

Calcium and potassium channels in experimental subarachnoid hemorrhage and transient global ischemia.

Healthy cerebrovascular myocytes express members of several different ion channel families which regulate resting membrane potential, vascular diameter, and vascular tone and are involved in cerebral autoregulation. In animal models, in response to subarachnoid blood, a dynamic transition of ion channel expression and function is initiated, with acute and long-term effects differing from each other. Initial hypoperfusion after exposure of cerebral vessels to oxyhemoglobin correlates with a suppression of voltage-gated potassium channel activity, whereas delayed cerebral vasospasm involves changes in other potassium channel and voltage-gated calcium channels expression and function. Furthermore, expression patterns and function of ion channels appear to differ between main and small peripheral vessels, which may be key in understanding mechanisms behind subarachnoid hemorrhage-induced vasospasm. Here, changes in calcium and potassium channel expression and function in animal models of subarachnoid hemorrhage and transient global ischemia are systematically reviewed and their clinical significance discussed.

Impact of various extents of experimental subarachnoid hemorrhage induced by the endovascular filament model on mortality and changes of cerebral blood flow

Objective: Among various animal models of subarachnoid hemorrhage (SAH), the endovascular filament model has been found particularly suitable to investigate acute pathophysiological changes after experimental SAH. Its major drawback, however, are high mortality and high variability of results. The present studies were carried out to examine the impact of various extents of experimental SAH in rats induced by different filament sizes. Methods: In study 1, Sprague-Dawley rats were subjected to vessel perforation with a 3-0, 4-0 or 5-0 monofila-ment or served as controls (n = 8). Intracranial pressure (ICP), mean arterial blood pressure (MABP), cerebral perfusion pressure (CPP) and local cortical blood flow (LCBF) were continuously monitored for 6 hours after SAH. 24 hours later, the animals were sacrificed to evaluate subarachnoid blood effusion. In study 2, the ani-mals were subjected to SAH using a 3-0 monofilament or served as controls (n = 8). After 7 days, they were sacrificed for quantification of tissue damage. Results: With increasing filament size, the decrease of CPP and LCBF and subarachnoid blood effusion were more pronounced. In all SAH-groups, the decline of LCBF after SAH exceeded the decline of CPP. Hippocam-pal damage was moderate but consistent. In both studies, the acute mortality was lower than previously re-ported. Conclusion: With controlled pre-hemorrhage blood pressure values and longer mechanical ventilation mortality can be kept low even if stronger filaments are used. The impact of subarachnoid vessel perforation on patho-physiological changes and blood effusion can be graded by the use of different filament sizes. The persisting mismatch between CPP and LCBF both in major and minor SAH suggests sustained vasoconstriction occurring independent of the extent of hemorrhage.

Report of Selective Cortical Infarcts in the Primate Clot Model of Vasospasm After Subarachnoid Hemorrhage

In human autopsy studies, 70% to 80% of patients with aneurysmal subarachnoid hemorrhage (SAH) showed infarcts in cerebral cortex covered by subarachnoid blood. Thus far, no animal model of SAH is known to produce this peculiar infarct pattern, and its pathogenesis remains enigmatic. To investigate whether such infarcts occur in the clot model of SAH in primates. We performed a retrospective pathological review of 16 primate brains. In 13 cynomolgus monkeys, a blood clot was placed around the middle cerebral artery after additional removal of the arachnoid membrane from the basal surface of the frontal and temporal cortexes. Three animals underwent sham surgery without placement of a blood clot (controls). The brains were harvested between days 1 and 28 after SAH and examined by a neuropathologist blinded to study group. We identified 2 types of cortical infarcts. A band of selective cortical laminar necrosis parallel to the cortical surface ("horizontal") was found in 5 animals. The second category of cortical lesions had a "vertical" extension. It included wedge-shaped (n = 2) or pillarlike (n = 2) necrosis. Both horizontal and vertical infarcts were located exclusively in areas adjacent to subarachnoid blood. The presence of a cortical infarct did not correlate with the degree of middle cerebral artery vasospasm (r2 = .24, P = .13). The presence of cortical infarcts suggests that a modified nonhuman primate model of SAH is suitable to examine the pathogenesis of proximal vasospasm and permits investigation of cortical lesions similar to those reported in patients after SAH. Furthermore, it indicates that direct effects of the blood clot on the brain and microcirculation contribute to the development of cortical infarcts after SAH.

Effects of ebselen versus nimodipine on cerebral vasospasm subsequent to experimental subarachnoid hemorrhage in rats

We investigated the effect of ebselen relative to nimodipine in an animal model of subarachnoid hemorrhage. Thirty Wistar albino rats were divided into 5 groups: G1, no intervention; G2, sham surgery without subarachnoid hemorrhage (SAH); G3, SAH only; G4, SAH plus nimodipine treatment; G5, SAH plus ebselen treatment. For G2 animals, physiological saline (0.9% NaCl) was injected into the cisterna magna. For G3, G4 and G5 animals, SAH was induced by injecting autologous non-heparinized blood into the cisterna magna. One hour after injection, G4 animals received nimodipine at 6-hour intervals and G5 animals received ebselen twice a day for 48 hours. After treatment, brain tissue and blood samples were taken for biochemical and histopathological examination. Mean malonyldialdehyde concentration was significantly higher in G3 than in G1 ( p < 0.0001), G2 ( p = 0.01), G4 ( p = 0.002) and G5 ( p = 0.014), and significantly higher in G5 than in G1 ( p = 0.013). Mean superoxide dismutase activity was significantly lower in G4 than in both G1 ( p = 0.025) and G2 ( p = 0.02). Mean wall thickness was significantly greater in G3 than in G1 ( p < 0.0001), G2 ( p = 0.01), G4 ( p < 0.0001) and G5 ( p < 0.0001). Mean wall thickness was also significantly greater in both G1 and G2 than in G4 ( p < 0.0014 and p < 0.0001) and G5 ( p < 0.0001 and p < 0.0001). Mean luminal diameter of the basilar artery was significantly smaller in G3 than in G2 ( p = 0.02), G4 ( p < 0.018) and G5 ( p < 0.001). Our results confirm that ebselen may have neuroprotective effects by acting to prevent vasospasm.

Experimental models of subarachnoid hemorrhage for studies of cerebral vasospasm

Objective: A multitude of subarachnoid hemorrhage (SAH) models have been described but only several of them are still in use. All models to a different degree helped in understanding of pathophysiology of cerebral vasospasm after SAH. Their advantages and drawbacks have been reviewed in this paper. Since 2000, when the last review on cerebral vasospasm in animal models was written, new animal models of SAH were introduced and our knowledge about pathophysiology of CVS improved. The aim of present review was to update the information about well established and newly implemented models of vasospasm after SAH.Materials and methods: The MEDLINE searches were carried out using keywords that included 'subarachnoid hemorrhage', 'animal', 'model', as well as names of animal species such as 'rats', 'dogs', 'mice', 'rabbits', 'pigs' or animal groups, e.g. 'non-human primates'. Owing to a limited volume, only models of SAH in vivo were included in our review.Results: We identified 53 original models of SAH in considered groups of animals. For the past several years, use of rats and mice became increasingly common in vasospasm studies due to advancements of imaging techniques, new approaches in vessel morphometry and reduced costs related to small animals. However, dog model of SAH is still considered superior for vasospasm studies as the ability of murine models to model human vasospasm is disputed.Conclusion: Testing new concepts of vasospasm etiology will require re-evaluation of in vivo models of CVS. The updated knowledge about their advantages and limitations is necessary for effective design in future studies of cerebral vasospasm after SAH.

Antivasospastic and antiinflammatory effects of caspase inhibitor in experimental subarachnoid hemorrhage

Inflammation in the subarachnoid space and apoptosis of arterial endothelial cells have been implicated in the development of delayed cerebral vasospasm after subarachnoid hemorrhage (SAH). The authors investigated mechanisms of possible antivasospastic effects of N-benzyl-oxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK), a caspase inhibitor that can inhibit both inflammatory and apoptotic systems, in animal models of SAH. Rabbits were assigned to three groups of eight animals each and were subjected to SAH by injection of blood into the cisterna magna. The experiments were performed in the following groups: SA only, SAH + vehicle, and SAH + Z-VAD-FMK. The Z-VAD-FMK (1 mg) or vehicle (5% dimethyl sulfoxide) was intrathecally administered before SAH induction. Diameters of the basilar artery (BA) were measured on angiograms obtained before and 2 days after SAH. The BA diameter on Day 2 was expressed as a percentage of that before SAH. Interleukin (IL)-1 in the cerebrospinal fluid (CSF) was examined using Western blotting, and brains were immunohistochemically examined for caspase-1 and IL-1beta. In a separate experiment, 20 rats were subjected to SAH and their brains were immunohistochemically assessed for caspase-1, IL-1beta, and macrophages. RESULTS. In rabbits, Z-VAD-FMK significantly attenuated cerebral vasospasm (the BA diameter on Day 2 in SAH-only, SAH + vehicle, and SAH + Z-VAD-FMK groups was 66.6 +/- 3.2%, 66.3 +/- 3.7%, and 82.6 +/- 4.9% of baseline, respectively), and suppressed IL-1beta release into the CSF and also suppressed immunoreactivities of caspase-1 and IL-1P in macrophages infiltrating into the subarachnoid space. Immunoreactivities for caspase-1 and IL-1P were observed in immunohistochemically proven infiltrating macrophages in rats. These results indicate that caspase activation may be involved in the development of SAH-induced vasospasm through inflammatory reaction.

Neurokinin-1 receptor antagonism in a rat model of subarachnoid hemorrhage: prevention of upregulation of contractile ETB and 5-HT1B receptors and cerebral blood flow reduction

Cerebral vasospasm following subarachnoid hemorrhage (SAH) leads to reduced cerebral blood flow (CBF) and to cerebral ischemia, in some cases even producing infarction and long-term disability. The goal of the present study was to investigate the hypothesis that inhibition of neurokinin-1 receptors (NK1Rs) by administration of L-822429 blunts the decrease in CBF as well as cerebrovascular receptor upregulation in an animal model of SAH. Subarachnoid hemorrhage was induced in rats by injection of 250 microl of blood into the prechiasmatic cistern. The NK1R inhibitor L-822429 was injected intracisternally 30 minutes and 24 hours after the induction of SAH. Two days after SAH induction, the basilar arteries were harvested, and contractile responses to endothelin-1 (ET-I, an ETA- and ETB-receptor agonist) and 5-carboxamidotryptamine (a 5-hydroxytryptamine- I1 [5-HT1]-receptor agonist) were investigated using sensitive myographs. To determine whether NKIR inhibition had an influence on local CBF after post-SAH, a quantitative autoradiographic technique was used. After SAH, the vascular receptor phenotype was changed in cerebral arteries through upregulation of contractile ET, and 5-HT1B receptors, while regional and total CBF were markedly reduced. Treatment with the selective NK1R inhibitor L-822429 prevented both the receptor upregulation and the reduction in regional and global CBF. The data reveal the coregulation of vascular receptor changes and blood flow effects, and also show that interaction with a small-molecule NK1R antagonist is a promising area of focus for the development of specific treatments for SAH.

Risk of cerebral vasopasm after subarachnoid hemorrhage reduced by statin therapy: a multivariate analysis of an institutional experience

Impairment of endothelial nitric oxide synthase (eNOS), endothelium-dependent relaxation, and cerebrovascular autoregulation all occur in vasospastic cerebral arteries following subarachnoid hemorrhage (SAH). The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, both improve endothelial function and increase eNOS messenger RNA, protein, and enzymatic activity threefold. Increasing experimental evidence in animal models of SAH suggests that statins may ameliorate cerebral vasospasm. The authors hypothesized that patients chronically treated with statins would have a decreased risk of symptomatic vasospasm after SAH. The authors retrospectively reviewed the charts of 115 patients with SAH who were consecutively admitted to the Neuroscience Intensive Care Unit of Duke University between 1998 and 2001. The independent association of statin therapy to symptomatic vasospasm was assessed using multivariate logistic regression analysis. Fifteen patients (13%) admitted with SAH were receiving statin therapy for at least 1 month before admission. Forty-nine patients (43%) experienced symptomatic vasospasm a mean of 5.8 +/- 3 days after onset of SAH. Current statin therapy on admission (odds ratio [OR] 0.09, 95% confidence interval [CI] 0.01-0.77) was independently associated with an 11-fold reduction in the risk of symptomatic vasospasm. Fisher Grade 3 SAH (OR 2.82, 95% CI 1.50-5.71) and rupture of anterior cerebral or internal carotid artery aneurysm (OR 3.77, 95% CI 1.29-10.91) were independently associated with an increased risk of symptomatic vasospasm. In this retrospective case series, patients who received statin therapy for at least 1 month demonstrated an 11-fold decrease in the risk of developing symptomatic vasospasm after SAH.

The Brain Erythropoietin System and its Potential for Therapeutic Exploitation in Brain Disease

The discovery of the broad neuroprotective potential of erythropoietin (EPO), an endogenous hematopoietic growth factor, has opened new therapeutic avenues in the treatment of brain diseases. EPO expression in the brain is induced by hypoxia. Practically all brain cells are capable of production and release of EPO and expression of its receptor. EPO exerts multifaceted protective effects on brain cells. It protects neuronal cells from noxious stimuli such as hypoxia, excess glutamate, serum deprivation or kainic acid exposure in vitro by targeting a variety of mechanisms and involves neuronal, glial and endothelial cell functions. In rodent models of ischemic stroke, EPO reduces infarct volume and improves functional outcome, but beneficial effects have also been observed in animal models of subarachnoid hemorrhage, intracerebral hemorrhage, traumatic brain injury, and spinal cord injury. EPO has a convenient therapeutic window upon ischemic stroke and favorable pharmacokinetics. Results from first therapeutic trials in humans are promising, but will need to be validated in larger trials. The safety profile and effectiveness of EPO in a wide variety of neurologic disease models make EPO a candidate compound for a potential first-line therapeutic for neurologic emergencies.