Signaling pathways for early brain injury after subarachnoid hemorrhage.

Few studies have examined the signaling pathways that contribute to early brain injury after subarachnoid hemorrhage (SAH). Using a rat SAH model, the authors explored the role of vascular endothelial growth factor (VEGF) and mitogen-activation protein kinase (MAPK) in early brain injury. Male Sprague-Dawley rats (n = 172) weighing 300 to 350 g were used for the experimental SAH model, which was induced by puncturing the bifurcation of the left anterior cerebral and middle cerebral arteries. The blood-brain barrier (BBB), brain edema, intracranial pressure, and mortality were evaluated at 24 hours after SAH. The phosphorylation of VEGF and different MAPK subgroups (ERK1/2, p38, and JNK) were examined in both the cortex and the major cerebral arteries. Experimental SAH increased intracranial pressure, BBB permeability, and brain edema and produced high mortality. SAH induced phosphorylation of VEGF and MAPKs in the cerebral arteries and, to a lesser degree, in the cortex. PP1, an Src-family kinase inhibitor, reduced BBB permeability, brain edema, and mortality and decreased the phosphorylation of VEGF and MAPKs. The authors conclude that VEGF contributes to early brain injury after SAH by enhancing the activation of the MAPK pathways, and that the inhibition of these pathways might offer new treatment strategies for SAH.     

Depression and anxiety in a Portuguese MS population: associations with physical disability and severity of disease

In cerebral ischemia, transmission by the inhibitory neurotransmitter, γ-aminobutyric acid (GABA) is altered. This study was performed to determine whether blockade of GABA(A) receptor would affect regional cerebral blood flow (rCBF) and blood-brain barrier (BBB) permeability in a focal ischemic area of the brain. Rats were anesthetized with isoflurane and mechanically ventilated. Fifteen minutes after a permanent middle cerebral artery (MCA) occlusion, one half of the rats were infused with bicuculline 1mg/kg/min iv for 2 min followed by 0.1mg/kg/min iv to the end of the experiment. The other half were infused with normal saline. At one hour after MCA occlusion, rCBF was determined using 1?C-iodoantipyrine and BBB permeability was determined by measuring the transfer coefficient (Ki) of 1?C-α-aminoisobutyric acid. With MCA occlusion, rCBF was decreased in the ischemic cortex (IC) (-70%) in the control rats. In the bicuculline treated rats, the rCBF of the IC was lower (-48%) than the contralateral cortex but higher than the rCBF of the IC of the control rats (+55%). MCA occlusion increased Ki in the IC of the control rats (+72%) and bicuculline administration increased Ki further (+53%) in the IC. Blockade of GABA(A) receptors did not significantly affect rCBF or BBB permeability in the non-ischemic brain regions under isoflurane anesthesia. Our data demonstrated that blockade of GABA(A) receptors increased rCBF and enhanced the BBB disruption in focal cerebral ischemia. Our data suggest that GABA(A) receptors are involved, at least in part, in modulating rCBF and BBB disruption in focal cerebral ischemia.     

Diffusion- and perfusion-weighted imaging in vasospasm after subarachnoid hemorrhage

BACKGROUND AND PURPOSE: Better measures of cerebral tissue perfusion and earlier detection of ischemic injury are needed to guide therapy in subarachnoid hemorrhage (SAH) patients with vasospasm. We sought to identify tissue ischemia and early ischemic injury with combined diffusion-weighted (DW) and hemodynamically weighted (HW) MRI in patients with vasospasm after SAH. METHODS: Combined DW and HW imaging was used to study 6 patients with clinical and angiographic vasospasm, 1 patient without clinical signs of vasospasm but with severe angiographic vasospasm, and 1 patient without angiographic spasm. Analysis of the passage of an intravenous contrast bolus through brain was used to construct multislice maps of relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), and tissue mean transit time (tMTT). We hypothesize that large HW imaging (HWI) abnormalities would be present in treated patients at the time they develop neurological deficit due to vasospasm without matching DW imaging (DWI) abnormalities. RESULTS: Small, sometimes multiple, ischemic lesions on DWI were seen encircled by a large area of decreased rCBF and increased tMTT in all patients with symptomatic vasospasm. Decreases in rCBV were not prominent. MRI hemodynamic abnormalities occurred in regions supplied by vessels with angiographic vasospasm or in their watershed territories. All patients with neurological deficit showed an area of abnormal tMTT much larger than the area of DWI abnormality. MRI images were normal in the asymptomatic patient with angiographic vasospasm and the patient with normal angiogram and no clinical signs of vasospasm. CONCLUSIONS: We conclude that DW/HW MRI in symptomatic vasospasm can detect widespread changes in tissue hemodynamics that encircle early foci of ischemic injury. With additional study, the technique could become a useful tool in the clinical management of patients with SAH.     

三种方法制作大鼠蛛网膜下腔出血模型

目的探讨三种方法制作大鼠蛛网膜下腔出血(SAH)模型的应用价值。方法分别采用颈内动脉穿刺法(PIC)、枕大池2次注血法(ACM)和交叉前池注血法(APC)制作大鼠SAH模型。观察不同模型的病死率、蛛网膜下腔血液分布及含量、脑血管痉挛程度及持续时间、伴发脑水肿、血-脑屏障(BBB)通透性等方面的改变。结果三种方法均成功制作SAH模型。病死率:PIC为46.2%,ACM为25.0%,APC为11.1%。血管痉挛高峰时间:PIC与APC均为第2天,第3～5天恢复正常;ACM为第5天,持续7 d。蛛网膜下腔血液量:ACM为(240.50±25.38)lμ,APC为(172.15±25.45)μl;PIC模型变异大,为60～520 lμ,平均(267.12±45.86)μl。PIC模型脑水肿最重,ACM与APC模型脑水肿相对较轻。PIC模型造成严重的BBB通透性损害,另两组损害程度相近。结论三种方法制成的模型适用于研究SAH不同病理生理改变的需要。PIC脑水肿重,病死率高,适用于SAH后脑损害的机制研究;ACM脑血管痉挛的时间特征与人SAH后血管痉挛接近,适用于血管痉挛的机制研究;APC血液恒定分布于前循环,病死率低,...     

Noninvasive measurement of cerebral vasopasm in patients with subarachnoid hemorrhage

Regional cerebral blood flow (rCBF) was measured as fast flow clearance (F1) and the initial slope index (ISI2) after inhalation of 133Xe in 30 patients with subarachnoid hemorrhage (SAH). Vasomotor responsiveness to reduction in end-tibal PECO2 was examined in those patients who could carry out this procedure satisfactorily as a test for the presence or absence of vasospasm. F1 and ISI2 were significantly reduced in patients with recent SAH compared to 35 age-matched normal volunteers. The degree of reduction of F1 and ISI2 correlated directly with severity of the neurological deficit graded according to the Hunt and Hess rating scale. Topographic reductions of rCBF correlated with angiographically demonstrated vasospasm or intracerebral hematoma. The degree of impairment of cerebral vasomotor responsiveness to reduction of PECO2 by hyperventilation also correlated with the severity of vasospasm demonstrated angiographically in 16 patients. The reductions of rCBF values were maximal during the first week after SAH but returned gradually toward normal by the 5th week. Individual patients with SAH whose lowest F1 values were above 50 ml/100 g brain/min tolerated surgical intervention best. Non-invasive measurements of rCBF after SAH appear to be helpful in estimating the presence and time course of vasospasm, in recognizing the development of normal pressure hydrocephalus, and in planning medical and surgical management.     

Subarachnoid haemorrhage in the rat: angiography and fluorescence microscopy of the major cerebral arteries

A subarachnoid haemorrhage (SAH) in the rat was produced by the injection of blood via a previously implanted catheter connected to the cisterna magna. Repeated angiographical examinations of the vertebro-basilar arteries revealed a biphasic vasospasm with a maximal acute spasm at ten minutes and a maximal late spasm at two days after cisternal blood injection. Fluorescence microscopical examination of the major cerebral arteries at day two after the SAH revealed a reduction in the fluorescence intensity and in the number of histochemically visible sympathetic nerve terminals.     

Impact of cerebral microcirculatory changes on cerebral blood flow during cerebral vasospasm after aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE: Cerebral microcirculatory changes during cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) are still controversial and uncertain. The aim of this study was to investigate the changes of cerebral microcirculation during cerebral vasospasm and to clarify the roles of microcirculatory disturbances in cerebral ischemia by measuring cerebral circulation time (CCT) and regional cerebral blood flow (rCBF). METHODS: In 24 cases with aneurysmal SAH, rCBF studies by single-photon emission CT and digital subtraction angiography (DSA) were performed on the same day between 5 and 7 days after SAH and/or within 4 hours after the onset of delayed ischemic neurological deficits. CCT was obtained by analyzing the time-density curve of the contrast media on DSA images and was divided into proximal CCT, which was the circulation time through the extraparenchymal large arteries, and peripheral CCT, which was the circulation time through the intraparenchymal small vessels. They were analyzed in association with rCBF and angiographic vasospasm. RESULTS: Severe angiographic vasospasm statistically decreased rCBF, and correlation between the degree of angiographic vasospasm and rCBF was seen (r=0.429, P=0.0006). Peripheral CCT showed strong inverse correlation with rCBF (r=-0.767, P<0.0001). Even in none/mild or moderate angiographic vasospasm, prolonged peripheral CCT was clearly associated with decreased rCBF. CONCLUSIONS: In addition to the marked luminal narrowing of large arteries detected as severe angiographic vasospasm, microcirculatory changes detected as prolonged peripheral CCT affected cerebral ischemia during cerebral vasospasm. These results suggested that impaired autoregulatory vasodilation or decreased luminal caliber in intraparenchymal vessels may take part in cerebral ischemia during cerebral vasospasm.     

Identification of blood-brain barrier function following subarachnoid hemorrhage in rats at different stages*☆

BACKGROUND： Recent studies have indicated that blood-brain barrier （BBB） disruption following subarachnoid hemorrhage （SAH） significantly correlates with the development of brain injury and poor prognosis of patients subjected to SAH. OBJECTIVE： To investigate both functional and structural changes related to BBB in various phases after SAH in rats through quantitative and qualitative methods. DESIGN, TIME AND SETTING： This experiment, a completely randomized design and controlled experiment, was performed at the Department of Neurosurgery, the Second Affiliated Hospital of Chongqing University of Medical Sciences from June 2006 to March 2007. MATERIALS： A total of 128 female, healthy, Sprague-Dawley rats were selected for this study. Main reagents and instruments： Evans Blue dye （Sigma Company, USA）, fluorescence spectrophotometer （Shimadzu Company, Japan）, and transmission electron microscope （Olympus Company, Japan）. METHODS： The included 128 rats were randomly divided into two groups： sham-operated group （n = 16） and SAH group （n = 112）. Rats in the SAH group were divided into seven subgroups： 6, 12, 24, 36, 48, 60, and 72 hours after SAH （16 rats for each time point）. Experimental SAH was induced by blood injection into the pre-chiasmatic cistern （300 μ L）. The sham-operated group received an equivalent volume of normal saline solution （300 μ L） injected into the subarachnoid space. MAIN OUTCOME MEASURES： Brain tissue water content was determined by the wet-dry method. BBB permeability in the cerebral cortex was determined by Evans Blue dye and fluorescent spectrophotometer. The ultrastructural changes in BBB were observed with transmission electron microscope. RESULTS： Compared with the sham-operated group, SAH induced a significant increase in brain water content between 24 and 60 hours （F = 888.32, P 〈 0.05）. Brain water content increased to a maximum by 36 hours after SAH, normalizing by 72 hours. Evans Blue content in the cerebral corte     

Anti-apoptotic and neuroprotective effects of Tetramethylpyrazine following subarachnoid hemorrhage in rats

This study was designed to explore the effects of Tetramethylpyrazine on cerebral vasospasm and early brain injury and its underlying mechanisms after experimental SAH in rats. Male Sprague-Dawley rats (n=164) were allocated randomly to SAH+TMP, SAH+vehicle (sodium chloride), or sham-operated group. The SAH model was induced through perforating internal carotid artery. TMP (30 mg/kg) or the vehicle was injected via vena caudalis 60 min before the perforation. Mortality, neurological scores, water content of brain and cerebral vasospasm were recorded at 24 h after SAH. Apoptosis of cerebral cortex was determined by TUNEL staining; caspase-3, bax and bcl-2 by Western blotting; P53 expression by immunohistochemical staining. TMP administrated in advance improved neurological scores, ameliorated cerebral edema and cerebral vasospasm. TUNEL-positive cells were reduced significantly in TMP-treated group. P53 was not found significantly different between TMP-treated and vehicle-treated group, while P53 positive cells were markedly higher in SAH group than that in sham-operated group. Cleaved caspase-3 protein was decreased significantly in TMP-treated group, while bax, bcl-2 protein expression did not differ statistically among the three groups. In conclusion, TMP ameliorated cerebral vasospasm and early brain injury after experimental SAH in rats. The underlying mechanisms may be partly related to inhibition of caspase-3 dependent proapoptosis pathway.     

4＇，5，7-三羟基异黄酮对蛛网膜下腔出血大鼠的神经保护和抗氧化作用研究

目的探讨4＇,5,7-三羟基异黄酮对蛛网膜下腔出血（SAH）后的神经保护作用。方法对大鼠单次枕大池注血模型分别以10mg／kg、50mg／kg浓度腹腔注射4＇,5,7-三羟基异黄酮,观察大鼠脑水肿、血脑屏障（BBB）的通透性、氧化应激和血红素氧合酶-1（HO-1）的变化情况。结果4＇,5,7-羟基异黄酮可以减轻SAH后脑水肿,降低BBB通透性、缓解氧化应激状态及减少HO-1的表达。结论4＇,5,7-三羟基异黄酮可能是通过提高内源性抗氧化酶的表达和抑制自由基的产生,从而在SAH中产生神经功能保护作用。     

The role of p53 in brain edema after 24 h of experimental subarachnoid hemorrhage in a rat model

Our previous study demonstrated that p53 plays an orchestrating role in the vasospasm and apoptotic cell death after subarachnoid hemorrhage (SAH). We now hypothesize that p53 also plays an important role in brain edema by up-regulating the expression of MMP-9 via the NF-κB molecular signaling pathway. Adult male rats (300-350 g) were divided into five groups (n = 20 each): Sham, SAH treatment with DMSO or PFT-α (0.2 mg/kg and 2.0 mg/kg), intraperitoneally. The monofilament puncture model was used to induce SAH and animals were subsequently sacrificed at 24 h. The blood-brain barrier (BBB) disruption, brain water content, MMP-9 activity, immunohistochemistry, treble fluorescence labeling, Western blot, and ultra-structural observations were performed. Evans blue extravagation, BBB diffuse leakage of IgG protein and brain water content were significantly reduced by PFT-α treatment; and the expression of p53, NF-κB and MMP-9 were significantly increased. The tight junction protein (Occludin) in endothelia cells and Collage IV in basal lamina were decreased in the brain of SAH rats, and were also modified by PFT-α treatment. Ultra-structural changes included disruption of endothelial tight junction and widening of the inter-endothelial spaces. Treble labeling showed p53 colocalized with NF-κB and MMP-9 in cerebral endothelia cells. We thus conclude that the level of p53 in cerebral microvasculature significantly affects the BBB permeability and brain edema after 24 h of SAH in rats. This can be at least partially ascribed to p53 inducing a significant up-regulation of MMP-9 via NF-κB in the endothelium, which in turn opened the tight junction by degrading Occludin and disrupting the basal lamina by degrading collagen IV.     

实验性兔症状性蛛网膜下腔出血后脑血管痉挛模型的建立

目的 建立可靠的兔症状性蛛网膜下腔出血（ＳＡＨ）后脑血管痉挛（ＣＶＳ）的模型。方法 采用双侧颈动脉结扎后枕大池２次注血制成兔ＳＡＨ模型,观察ＳＡＨ前后动物进食量和神经功能改变,以氢清除法检测局部脑血流量。结果 ＳＡＨ后动物进食量下降、神经功能障碍和ｒＣＢＦ下降,且ｒＣＢＦ随出血时间延长和出血量增加而下降更为明显。结论 兔双侧劲动脉结扎后枕大池２次     

大鼠蛛网膜下腔出血后早期脑损伤模型的建立

目的 建立一种微创、重复性好的大鼠蛛网膜下腔出血后早期脑损伤动物模型.方法 采用视交叉前池注血法建立蛛网膜下腔出血( SAH)后早期脑损伤(EBI)动物模型.在脑立体定位仪引导下将导管插入视交叉前池,注入300μl自体动脉血建立SAH后EBI模型.进行神经功能学评分,采用激光多普勒血流量仪(LDF)测定局部脑血流量(rCBF),解剖观察前循环周围血液分布情况,应用透射电子显微镜观察海马区神经细胞超微结构变化.结果 大部分大鼠在SAH后有神经行为学异常,48 h后逐渐恢复正常.SAH后不同时间点的rCBF均低于对照组.模型组大鼠颅脑解剖发现前循环蛛网膜下腔有大量的血液和血凝块.透射电子显微镜观察:与对照组比较,SAH组神经细胞线粒体和内质网肿胀,核染色质凝聚、趋边.结论 此动物模型稳定可靠,重复性高,适合进行临床前循环动脉瘤性蛛网膜下腔出血后早期脑损伤病理生理研究.     

非开颅蛛网膜下腔出血大鼠脑血流量和水、电解质含量研究

利用非开颅大鼠模型观察蛛网膜下腔出血（ＳＡＨ）后２４ｈ内脑血流量和水电解质含量的动态变化和尼莫地平对其影响。结果发现ＳＡＨ后脑血迅速降低，１ｈ了低值，２４ｈ内持于低水平状态。ＳＡＨ后１ｈ开始脑组织Ｃａ＾２＋答聚，６ｈ后出现脑水肿。尼莫地平对上述指标均有改善作用。提示脑血管痉挛及微循环异常所致脑血流减少在ＳＡＨ继发性的损害中起重要作用，尼莫地平可减轻上述病理改变。     

鼠脑血管痉挛时尼莫地平对体感诱发电位的影响

目的 探讨蛛网膜下腔出血（SAH）后脑血管痉挛（CVS）对体感诱发电位（SEP）的影响,及尼莫地平（ND）的保护作用。方法 对单纯SAH组和ND处理组大鼠观察手术前后基底动脉管径,并检测24h内局部脑血流量（rCBF)、SEP潜伏期及脑组织内皮素-1（ET-1）含量的动态变化。结果 SAH组大鼠在诱导SAH后rCBF立即降低,并持续24h,同时有基底动脉痉挛;SAH后1h开始至24hSEP潜伏期逐渐延长,脑组织ET-1含量显著增加,ND处理组大鼠上述变化均较轻。结论 SAH后CVS可通过脑血流的降低,脑组织ET-1增加而导致SEP潜伏期延长,ND通过拮抗脑组织ET-1变化而对之具有保护作用。     

Cerebral oxygen metabolism after aneurysmal subarachnoid hemorrhage

Previous studies of cerebral oxygen metabolism and extraction in patients with subarachnoid hemorrhage (SAH) have yielded conflicting results. We used positron emission tomography (PET) to measure the regional cerebral metabolic rate for oxygen (rCMRO2), oxygen extraction fraction (rOEF), and cerebral blood flow (rCBF) 16 times in 11 patients with aneurysmal SAH. All studies were performed preoperatively; no patient had hydrocephalus or intracerebral hematoma on brain CT. Eight patients with no arteriographic vasospasm who were studied on days 1-4 post-SAH had a significant 25% reduction in global CMRO2 compared to age-matched controls, and no significant change in global OEF, suggesting a primary reduction in CMRO2 caused by SAH. Four patients studied seven times during arteriographic vasospasm had significantly increased rOEF with unchanged CMRO2 in arterial territories affected by arteriographic vasospasm compared to territories without vasospasm, indicative of cerebral ischemia without infarction. No brain regions studied with PET were infarcted on follow-up CT. We conclude that the initial aneurysm rupture produces a primary reduction in CMRO2, and that subsequent vasospasm causes ischemia.     

Effects of S-nitrosoglutathione on acute vasoconstriction and glutamate release after subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Subarachnoid hemorrhage (SAH) causes acute vasoconstriction that contributes to ischemic brain injury shortly after the initial bleed. It has been theorized that decreased availability of nitric oxide (NO) may contribute to acute vasoconstriction. Therefore we examined the effect of the NO donor N-nitroso glutathione (GSNO) on acute vasoconstriction and early ischemic glutamate release after experimental SAH. METHODS: SAH was induced by the endovascular suture method in anesthetized rats. GSNO (1 micromol/L/kg, n=31) or saline (n=21) was injected 5 minutes after SAH. Sham-operated rats received GSNO (1 micromol/L/kg, n=5) 5 minutes after sham surgery. Arterial and intracranial pressures, cerebral blood flow (CBF), and extracellular glutamate release were measured serially for 60 minutes after SAH. SAH size was determined, and vascular measurements were made histologically. RESULTS: GSNO had no effect on resting blood pressure, intracranial pressure, cerebral perfusion pressure, or CBF in sham-operated animals. However, administration of GSNO after SAH was associated with significantly increased CBF (161.6+/-26.6% versus saline 37.1+/-5.5%, 60 minutes after SAH, P<0.05), increased blood vessel diameter (internal carotid artery [ICA] 285.0+/-16.5 microm versus saline 149.2+/-14.1 microm, P<0.01), decreased vessel wall thickness (ICA12.9+/-0.7 microm versus saline 25.1+/-1.6 microm, P<0.01), and decreased extracellular glutamate levels (3315.6+/-1048.3% versus saline469. 7+/-134.3%, P<0.05). Blood pressure decreased transiently, whereas intracranial pressure, cerebral perfusion pressure, and SAH size were not affected. CONCLUSIONS: These results suggest that GSNO can reverse acute vasoconstriction and prevent ischemic brain injury after SAH. This further implies that acute vasoconstriction contributes significantly to ischemic brain injury after SAH and is mediated in part by decreased availability of NO.     

颅脑损伤后TCD变化及其与伤情,CT及预后的相关性研究

目的 探讨：①脑外伤后ＴＣＤ的表现和变化规律;②ＴＣＤ与伤情、ＣＴ的关系;③ＴＣＤ与预后的关系。方法 选择３０例于伤后２４￣４８ｈ内入院的成年脑外伤病人（无明显复合伤,伤前无明显心脑血管疾病及严重感染）,动态行ＴＣＤ测定,同时行ＣＴ检查,并记录ＧＣＳ。结果 ①伤后１￣３ｄ已开始出现血管痉挛,６￣８ｄ达峰值,１３￣１５ｄ已明显减轻;②ＧＣＳ的变化有关,重伤组血管痉挛的发生率和程度均明显高于轻伤组;③     

蛛网膜下腔出血后早期海马ADAMTS-1的表达与血脑屏障通透性的相关性研究

目的研究大鼠蛛网膜下腔出血(subarachnoid hemorrhage,SAH)后早期海马组织中ADAMTS-l(a disintegrin-like and metalloproteinase with thrombospondin type l motifs)表达情况及其与血脑屏障通透性的关系,初步探讨ADAMTS-l在实验性大鼠SAH后早期脑损伤(early brain injury,EBI)中的作用。方法成年雄性SD大鼠108只,分假手术组和SAH组。采用大鼠视交叉前池注血模型,于SAH后6、12、24、48、72 h时间点,应用Western-Blotting和RT-PCR法检测大鼠海马ADAMTS-1蛋白及mRNA表达变化,同时应用甲酰胺浸泡法检测大鼠脑内伊文氏蓝(Evans blue,EB)含量。结果大鼠SAH后6 h、12 h组海马ADAMTS-1mRNA及蛋白表达与sham组相比无统计学意义,于出血后24 h表达明显升高,48 h达到高峰,72 h后仍维持在较高水平。脑内伊文氏蓝含量亦于出血后24 h明显升高,48 h达到高峰并于72 h仍维持在较高水平。ADAMTS-1蛋白表达与脑内EB含量成正相关(r=0.936,P=0.014)。结论大鼠SAH后早期脑损伤过程中ADAMTS-l的表达与血脑屏障损伤成正相关,提示ADAMTS-l可能参与SAH后早期脑损伤的病理过程。