The proteasome inhibitor VELCADE reduces infarction in rat models of focal cerebral ischemia

The potential neuroprotective effects of VELCADE were investigated in two different models of focal cerebral ischemia. For time-window assessment, male Wistar-Kyoto rats were treated with 0.2 mg/kg VELCADE at 1, 2, or 3 h after the induction of permanent middle cerebral artery occlusion (MCAO) using the suture occlusion method (experiment 1). To evaluate effects in a different model, male Sprague-Dawley rats received 0.2 mg/kg VELCADE after embolic MCAO (experiment 2). Infarct volume was calculated based on TTC-staining 24 h postischemia and whole blood proteasome activity was fluorometrically determined in both experiments at baseline, 1 and 24 h post-MCAO. In experiment 1, a dose of 0.2 mg/kg inhibited proteasome activity by 77% and infarct volume was reduced to 175.7+/-59.9 mm3 and 205.9+/-83.9 mm3 (1 and 2 h group, respectively; p<0.05) compared to 306.5+/-48.5 mm3 (control). Treatment at 3 h was not neuroprotective (293.0+/-40.1 mm3). After embolic MCAO, infarct volume was 167.5+/-90.7 mm3 (treatment group) and 398.9+/-141.3 mm3 (control; p=0.002). In conclusion, VELCADE treatment inhibited whole blood proteasome activity and achieved significant neuroprotection in two rat models of focal cerebral ischemia at various time points poststroke.     

辣椒素受体拮抗剂AMG517在小鼠脑缺血/再灌注损伤中通过调节炎症因子释放发挥神经保护作用#br#

目的 观察辣椒素受体(TRPV1)拮抗剂AMG517在小鼠脑缺血/再灌注损伤中的作用及相关机制。方法 40只雄性C57BL/6小鼠随机分为假手术组(sham,n=10)、赋形剂（vehicle）+缺血/再注灌注组(vehicle,n=10)、辣椒素+缺血/再注灌注组(capsaicin,n=10)和AMG517+缺血/再注灌组(AMG517,n=10)。采用大脑中动脉闭塞(MCAO)诱导缺血/再灌注损伤,再灌注72 h进行神经行为学评分;同时检测各组小鼠梗死体积、脑水肿、TRPV1 mRNA表达和血清肿瘤坏死因子-α(TNF-α)浓度及白细胞介素-10(IL-10)浓度。结果 与vehicle组相比,AMG517显著减小鼠脑梗死体积(P<0.01)。AMG517给药后也可显著降低小鼠神经行为学评分(P<0.01)。与sham组比较,vehicle组TRPV1 mRNA表达显著增加(P<0.01)。AMG517给药后可显著增加抗炎性细胞因子IL-10浓度,并降低炎性细胞因子TNF-α浓度(P<0.05)。结论 AMG517可改善小鼠缺血/再灌注损伤,可能是通过缓解炎症发挥神经保护作用。     

Comparison between coated vs. uncoated suture middle cerebral artery occlusion in the rat as assessed by perfusion/diffusion weighted imaging

Differences among models in the temporal evolution of ischemia after middle cerebral artery occlusion (MCAO) in rats may considerably influence the results of experimental treatment studies. Using diffusion and perfusion imaging, we compared the spatiotemporal evolution of ischemia in Sprague-Dawley rats after permanent MCAO (pMCAO) with different types of sutures. Male Sprague-Dawley rats were randomly assigned to pMCAO produced with either 4-0 silicone coated (n=8), or 3-0 uncoated monofilaments (n=8). Serial determination of quantitative cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) maps were performed up to 3 h after pMCAO. Lesion volumes were calculated by using previously validated thresholds and correlated with infarct volume corrected for edema defined by 2,3,5-triphenyltetrazolium chloride (TTC) staining at 24 h after MCAO. The ADC/CBF-defined mismatch volume in the 4-0 coated suture model was present significantly longer (up to 120 min) compared to the uncoated 3-0 suture model (30 min). The TTC-derived infarct volume was significantly larger in the coated model (290.3+/-32.8 mm(3)) relative to the uncoated model (252.3+/-34.6 mm(3)). This study demonstrates that the type of suture may significantly influence the spatiotemporal evolution of the ADC/CBF-mismatch as well as the final infarct volume. These inter-model variations must be taken into account when assessing new therapeutic approaches on ischemic lesion evolution in the rat MCAO model.     

Delayed hyperbaric oxygenation is more effective than early prolonged normobaric hyperoxia in experimental focal cerebral ischemia

Hyperbaric (HBO) and normobaric (NBO) oxygen therapy have been shown to be neuroprotective in focal cerebral ischemia. In previous comparative studies, NBO appeared to be less effective than HBO. However, the experimental protocols did not account for important advantages of NBO in the clinical setting such as earlier initiation and prolonged administration. Therefore, we compared the effects of early prolonged NBO to delayed HBO on infarct size and functional outcome. We also examined whether combining NBO and HBO is of additional benefit. Wistar rats underwent filament-induced middle cerebral artery occlusion (MCAO) for 150 min. Animals breathed either air, 100% O(2) at ambient pressure (NBO; initiated 30 min after MCAO) 100% O(2) at 3 atm absolute (HBO; initiated 90 min after MCAO), or a sequence of NBO and HBO. Infarct volumes and neurological outcome (Garcia score) were examined 7d after MCAO. HBO (174+/-65 mm(3)) significantly reduced mean infarct volume by 31% compared to air (251+/-59 mm(3)) and by 23% compared to NBO treated animals (225+/-63 mm(3)). In contrast, NBO failed to decrease infarct volume significantly. Treatment with NBO+HBO (185+/-101 mm(3)) added no additional benefit to HBO alone. Neurological deficit was significantly smaller in HBO treated animals (Garcia score: 13.3+/-1.2) than in animals treated with air (12.1+/-1.4), but did not differ significantly from NBO (12.4+/-0.9) and NBO+HBO (12.8+/-1.1). In conclusion, HBO is a more effective therapy than NBO in transient experimental ischemia even when accounting for delayed treatment-onset of HBO. The combination of NBO and HBO results in no additional benefit.     

Decrease of the electroacupuncture-induced analgesic effects in nuclear factor-kappa B1 knockout mice

We investigated whether pre-treatment with melatonin, a potent free radical scavenger and antioxidant, would protect against permanent focal cerebral ischemia without reperfusion in a rat middle cerebral artery occlusion (MCAO) model. A single dose of melatonin at 5, 15, or 50 mg/kg or the vehicle alone was given via an intraperitoneal injection at 0.5 h before permanent MCAO. Relative infarction volumes on day 3 were significantly reduced in the groups treated with melatonin at 5 (mean+/-SEM, 17.0+/-6.5%), 15 (18.1+/-5.8%), or 50 (20.6+/-5.0%) mg/kg when compared with the vehicle-treated group (37.1+/-2.8%) and so melatonin treatment achieved a relative reduction in infarct volume by 54.2, 51.2 and 44.5%, respectively. Melatonin did not affect the hemodynamic parameters. Thus, pre-treatment with melatonin at a dose between 5 and 50 mg/kg protects against focal cerebral ischemia without reperfusion.     

脑的不对称性影响大鼠局灶性脑缺血的结局

为评价左右侧大脑中动脉闭塞(MCAO)对右利大鼠神经行为功能和脑梗死体积的影响,本研究应用四足动物觅食实验筛选右利爪雄性SD大鼠24只,随机分为经左、右侧插线组各12只,8%水合氯醛腹腔注射(300mg/kg)麻醉,线栓法经左、右侧颈外-内动脉插入头端涂有多聚赖氨酸的4-0尼龙线,建立大鼠MCAO缺血2h模型,再灌注72h后评价动物的神经行为功能,测量脑梗死体积。结果表明,所有动物在脑缺血2h神经功能缺损评分最高,再灌注1、24、48和72h经左侧MCAO大鼠显著高于经右侧MCAO大鼠(P<0.05),后者功能明显优于前者,脑梗死体积经左侧插线的大鼠显著大于经右侧插线的大鼠(P<0.05)。研究结果提示,大鼠主侧半球大脑中动脉缺血后,神经功能缺损和脑梗死体积较对侧严重,脑的不对称性影响大鼠局灶性脑缺血的最终结局。     

Ghrelin对脑缺血再灌注大鼠脑水肿和水通道蛋白4表达的影响

 目的： 探讨ghrelin对脑缺血再灌注大鼠脑水肿、血脑屏障通透性及水通道蛋白4（AQP4）表达的影响。方法： 成年SD雄性大鼠随机分为3组:sham组、大脑中动脉阻塞（MCAO）组和ghrelin处理组。采用线栓法复制MCAO模型（缺血2 h,再灌注22 h）。Ghrelin组大鼠于再灌开始时经股静脉注射ghrelin 10 nmol/kg。TTC染色观察脑梗死体积,神经功能评分判断脑功能障碍程度,分别以体积计算和干湿重法检测脑肿胀程度和脑含水量的变化,收集脑血管外伊文思蓝(EB)来评估血脑屏障的破坏程度,免疫组化和Western blotting检测AQP4的表达变化。结果： 与MCAO组比较,ghrelin处理组的脑梗死体积较小（P<0.01）,神经功能评分较低（P<0.01）,脑组织中的EB渗出量较少（P<0.01）。Ghrelin处理组大鼠的脑肿胀体积、脑含水量和AQP4表达明显低于MCAO组（P<0.05）。结论： Ghrelin减轻大鼠脑缺血/再灌注损伤,减轻脑水肿和血脑屏障的破坏,抑制脑组织中AQP4的表达。AQP4在ghrelin的脑保护机制中可能发挥重要作用。     

大鼠脑缺血后血管内皮生长因子和血管生成素的表达变化及其作用

目的 探讨大鼠脑缺血后血管内皮生长因子(VEGF)和血管生成素(angiopoietin,Ang)的表达变化及其在血管生成和血管通透性变化中的作用.方法 选择160只雄性SD大鼠,采用随机区组法分为假手术组,缺血2h、6h、12h、1d、3d、7d和14d组,用线栓法制作大脑中动脉阻塞脑缺血损伤模型,分别于脑缺血后不同时间点处死大鼠.通过逆转录聚合酶链反应(RT-PCR)、Western blot及免疫组织化学方法检测大鼠脑缺血后不同时间点VEGF、Ang-1及Ang-2 mRNA和蛋白的表达变化.CD31标记鼠脑缺血后不同时间点的血管数量.Evans blue检测血脑屏障通透性.结果 大鼠脑缺血后VEGF mRNA表达逐渐增高,12 h达第一个高峰(0.7249 ±0.1933,P＜0.01),7d达第二个高峰(0.5264±0.1519,P＜0.01);VEGF蛋白表达也逐渐增高,于12 h达高峰(1.1017±0.1302,P＜0.01).Ang-2 mRNA和蛋白在脑缺血组织也逐渐增高,均12 h达高峰(0.6747±0.2416,P＜0.01;1.1197±0.1780,P＜0.01).与之相反,Ang-1 mRNA和蛋白表达逐渐降低,分别于3 d(0.3220±0.1427,P＜0.01)和1 d(0.1298±0.0293,P＜0.01)达最低水平,这些因子在脑缺血后的表达促进血管生成.脑缺血后血管通透性逐渐增加,EB含量在缺血1d达高峰[(6.219±0.887) μg/g,P＜0.01].结论 大鼠脑缺血后VEGF、Ang-1和Ang-2共同协调作用促进血管生成,在组织损伤修复过程中发挥着重要的作用.     

Ischaemic preconditioning in the rat brain: a longitudinal magnetic resonance imaging (MRI) study

Ischaemic preconditioning in rats was studied using MRI. Ischaemic preconditioning was induced, using an intraluminal filament method, by 30 min middle cerebral artery occlusion (MCAO), and imaged 24 h later. The secondary insult of 100 min MCAO was induced 3 days following preconditioning and imaged 24 and 72 h later. Twenty-four hours following ischaemic preconditioning most rats showed small sub-cortical hyperintense regions not seen in sham-preconditioned rats. Twenty-four hours and 72 h following the secondary insult preconditioned animals showed significantly smaller lesions (24 h = 112 +/- 31 mm(3), mean +/- standard error; 72 h = 80 +/- 35 mm(3)), which were confined to the striatum, than controls (24 h = 234 +/- 32 mm(3), p = 0.026; 72 h = 275 +/- 37 mm(3), p = 0.003). In addition during lesion maturation from 24 to 72 h post-secondary MCAO, preconditioned rats displayed an average reduction in lesion size as measured by MRI whereas sham-preconditioned rats displayed increases in lesion size; this is the first report of such differential lesion volume evolution in cerebral ischaemic preconditioning. Copyright -Copyright 2001 John Wiley & Sons, Ltd.     

脂肪来源的干细胞移植对大鼠脑缺血后微血管生成及bFGF和VEGF表达的影响

目的:探讨脂肪来源的干细胞(ADSC)移植对大鼠脑缺血后微血管生成的可能机制.方法:72只清洁级成年雄性Sprague-Darley大鼠, 随机分为假手术组(Sham组)、局灶性脑缺血组(MCAO组)、溶剂对照组(vehicle组)和ADSC治疗组(ADSC组), 每组18 只, 采用改良Zea-Longa线栓法制作大脑中动脉栓塞(MCAO)模型, ADSC移植前用DAPI标记, ADSC 组于造模成功1 d后经侧脑室注射入30 μL的经DAPI标记的ADSC细胞悬液, 内含1×106细胞, vehicle组则注射同等剂量的PBS, 术后4 d、7 d和14 d分批处死实验动物, 并断头取脑, 采用免疫组织化学法和半定量RT-PCR法检测缺血区脑组织的新生血管及bFGF和VEGF表达的动态变化.结果:大鼠脑缺血后缺血区即可见大量的微血管生成, 2周达高峰.ADSC组较MCAO组和vehicle组缺血区微血管密度明显增高(P＜0.01);ADSC组术后4 d、7 d和14 d脑组织中bFGF和VEGF的表达水平较MCAO组和vehicle组明显增高.结论:ADSC移植促进脑缺血大鼠缺血区微血管的生成, 其机制可能与促进bFGF和VEGF的表达有关.     

大鼠侧脑室注射VEGF重组质粒预防脑缺血再灌注损伤及其对PI3K／AKT通路的影响

目的：探讨血管内皮生长因子（VEGF）重组质粒预先导入鼠脑能否有效预防缺血性脑梗塞并初探其可能的作用机制。方法将pIERS2-EGFP/VEGF重组质粒预先注入质粒组大鼠侧脑室,通过大脑中动脉（MCA）线栓法制备大鼠局灶性缺血2h/再灌注24h模型,采用TTC染色法测量梗塞灶大小;用电镜观察鼠脑神经元超微结构的变化;并通过Western印迹方法检测各组鼠脑中P-AKT蛋白的表达。结果①VEGF质粒组右脑梗死体积较缺血组明显减小（P＜0．01）。②与缺血组相比,质粒组神经元损伤和水肿程度明显降低。③与正常组相比,缺血组与质粒组的P-AKT表达量均显著增加（P＜0．01）,且质粒组比缺血组增加显著（P＜0．01）。结论VEGF重组质粒的导入能有效预防缺血性脑梗塞,推测该机制可能是VEGF蛋白的表达能进一步活化PI3K/AKT信号通路。该研究为缺血性脑梗塞的二级预防提供一条新思路。     

小鼠脑缺血时自噬相关基因5的抗损伤作用

 目的: 观察自噬相关基因5(Atg5)在小鼠脑缺血再灌注损伤中的抗损伤作用。方法: 将雄性BALB/c小鼠随机分为假手术(sham)组、缺血再灌注(I/R)组、Atg5 siRNA组和control siRNA组。I/R组采用大脑中动脉阻塞(MCAO)60 min后再灌注24 h。Atg5 siRNA组和control siRNA组将5 μL Atg5 siRNA或scrambled siRNA在MCAO前24 h侧脑室注射。实时荧光定量PCR和Western blot检测Atg5的表达;2,3,5-氯化三苯基四氮唑(TTC)染色法检测抑制Atg5对缺血再灌注损伤后脑梗死面积和水肿率的影响;神经行为学评分法检测抑制Atg5对缺血再灌注损伤后神经症状的影响。结果: MCAO后再灌24 h,缺血半影区Atg5 mRNA和蛋白水平显著增高(P<0.05);Atg5 siRNA明显降低缺血再灌后Atg5 mRNA和蛋白的表达(P<0.05);侧脑室给予Atg5 siRNA能显著增加脑梗死面积和水肿率,并加重神经行为学损伤(P<0.05)。结论: 沉默Atg5加重小鼠脑缺血再灌损伤,提示MCAO后诱导的 Atg5 可减轻小鼠局灶性脑缺血再灌注损伤。     

Cyclooxygenase-2 mediates the development of cortical spreading depression-induced tolerance to transient focal cerebral ischemia in rats

We examined the role of cyclooxygenase-2 in the development of ischemic tolerance induced by cortical spreading depression against transient, focal brain ischemia. Cortical spreading depression was continuously induced for 2 h with topical KCl (13+/-1 depolarizations/2 h) in male Wistar rats. At 1, 2, 3, 4, and 5 days following recovery, the middle cerebral artery was transiently occluded for 120 min. Four days later, the animals were killed and infarct volume was determined. Additionally, cyclooxygenase-2 levels in the cerebral cortex and 15 deoxy-Delta(12, 14) PGJ2 levels in cerebrospinal fluid were determined at these times with Western blotting and immunoassay, respectively. Infarct volume was reduced compared with non-cortical spreading depression control animals (274.3+/-15.3 mm3) when cortical spreading depression was performed 3 and 4 days before middle cerebral artery occlusion (163.9+/-14.2 mm3, 154.9+/-14.2 mm3) but not at 1, 2 and 5 days (280.4+/-17.3 mm3, 276.3+/-16.9 mm3 and 268.5+/-17.3 mm3). Cyclooxygenase-2 levels increased most dramatically starting at 2 days, peaked at 3 days, and started to return toward baseline at 4 days after cortical spreading depression. 15 Deoxy-Delta(12, 14) PGJ2 levels increased from 134.7+/-83 pg/ml at baseline to 718+/-98 pg/ml at 3 days. Administration of N-[2-cyclohexyloxy-4-nitrophenyl] methanesulphonamide (10 mg/kg, i.v.), a selective cyclooxygenase-2 inhibitor, at 1 h prior to middle cerebral artery occlusion in cortical spreading depression preconditioned animals did not affect infarct volume (162.6+/-62.1 mm3). However, administration of N-[2-cyclohexyloxy-4-nitrophenyl] methanesulphonamide given three times prior to middle cerebral artery occlusion prevented the reduced infarct volume induced by cortical spreading depression preconditioning (272.9+/-63.2 mm3). Administration of L-nitro-arginine methyl ester (4 mg/kg, i.v.) prior to cortical spreading depression blocked increases in cyclooxygenase-2 normally seen at 3 and 4 days. We conclude that NO-mediated cyclooxygenase-2 upregulation by cortical spreading depression protects the brain against ischemic damage.     

Angiotensin type 1 receptor blockage improves ischemic injury following transient focal cerebral ischemia

Following cerebral ischemia, i.v. infusion of angiotensin II increases cerebral edema and mortality. Angiotensin type 1 receptor blockage should therefore improve acute cerebral ischemia. Left middle cerebral artery occlusion (120 min) followed by reperfusion was performed with the thread method under halothane anesthesia in Sprague-Dawley rats. Olmesartan (angiotensin type 1 receptor blocker; 0.01 or 0.1mumol/kg/h) was infused i.p. for 7 days following middle cerebral artery occlusion followed by reperfusion. Stroke index score, infarct volume, specific gravity, and brain angiotensin II and matrix metalloproteinases were quantified in the ischemic and non-ischemic hemispheres. Olmesartan treatment improved stroke index score, infarct volume, and cerebral edema in our cerebral ischemia model. In particular, stroke index score, infarct volume, and cerebral edema were reduced even with a low dose of olmesartan that did not decrease blood pressure. Paralleling these effects on cerebral ischemia, olmesartan treatment also reduced the reactive upregulation in brain angiotensin II, matrix metalloproteinase-2, matrix metalloproteinase-9, and membrane type 1-matrix metalloproteinase in the ischemic area. Angiotensin type 1 receptor stimulation may be one of the important factors that cause cerebral edema following cerebral ischemia, and that its inhibition may be of therapeutic advantage in cerebral ischemia.     

A novel calpain inhibitor, ((1S)-1((((1S)-1-benzyl-3-cyclopropylamino-2,3-di-oxopropyl)amino)carbonyl)-3-methylbutyl) carbamic acid 5-methoxy-3-oxapentyl ester, protects neuronal cells from cerebral ischemia-induced damage in mice

Cerebral ischemia induces Ca(2+) influx into neuronal cells, and activates several proteases including calpains. Since calpains play important roles in neuronal cell death, calpain inhibitors may have potential as drugs for cerebral infarction. ((1S)-1((((1S)-1-Benzyl-3- cyclopropylamino-2,3-di-oxopropyl)amino)carbonyl)-3-methylbutyl) carbamic acid 5-methoxy-3-oxapentyl ester (SNJ-1945) is a novel calpain inhibitor that has good membrane permeability and water solubility. We evaluated the effect of SNJ-1945 on the focal brain ischemia induced by middle cerebral artery occlusion (MCAO) in mice. Brain damage was evaluated by assessing neurological deficits at 24 h or 72 h after MCAO and also by examining 2,3,5-triphenyltetrazolium chloride (TTC) staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining of brain sections. When injected at 1 h after MCAO, SNJ-1945 at 30 and 100 mg/kg, i.p. decreased the infarction volume and improved the neurological deficits each assessed at 24 h. SNJ-1945 at 100 mg/kg, i.p. also showed neuroprotective effects at 72 h and reduced the number of TUNEL-positive cells at 24 h. SNJ-1945 was able to prevent neuronal cell death even when it was injected at up to 6 h, but not at 8 h, after MCAO. In addition, SNJ-1945 decreased cleaved alpha-spectrin at 6 h and 12 h, and active caspase-3 at 12 h and 24 h in ischemic brain hemisphere. These findings indicate that SNJ-1945 inhibits the activation of calpain, and offers neuroprotection against the effects of acute cerebral ischemia in mice even when given up to 6 h after MCAO. SNJ-1945 may therefore be a potential drug for stroke.     

Hyperbaric oxygen treatment attenuated the decrease in regional glucose metabolism of rats subjected to focal cerebral ischemia: a high resolution positron emission tomography study

Cerebral hypoxia may be the main component of cell damage caused by ischemia. Previous studies demonstrated a neuroprotective effect of early hyperbaric oxygen (HBO) treatment in various animal models of focal cerebral ischemia. Neuropathologic study showed that exposure of HBO may prevent cell death in ischemic cortex. In the present study, we aimed to assess cellular function of ischemic rat brain after HBO treatment by means of a high-resolution positron emission tomography scanner (microPET) used specifically for small animal imaging. The male Sprague-Dawley rats were subjected to permanent middle cerebral artery occlusion (MCAO), with the regional cerebral blood flow monitored in vivo by laser Doppler flowmetry. One hour after ischemia, HBO therapy (3 atm absolute, 1 h) was initiated. Local cerebral glucose utilization in the ischemic area was measured before, 1 h and 3 h after ischemia, with 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) as a tracer. Neurological deficits and infarct volumes were assessed at 24 h after ischemia. Our study showed that early HBO therapy significantly reduced infarct volume of brain 24 h after ischemia. Moreover, glucose utilization in the ischemic area underwent a severe decrease during 1-3 h after MCAO, while the early HBO treatment significantly attenuated the decrease in cerebral metabolic rate of glucose in the ischemic core of the cortex compared with controls. We report for the first time the application of microPET to quantify the rates of glucose metabolism in the ischemic core of rats exposed to HBO. Our results suggest that the early exposure of HBO can partially reverse the downward trend for glucose utilization in the ischemic core, which might contribute to the reported beneficial effects of early HBO therapy on permanent cerebral ischemia.     

Rapid tolerance to focal cerebral ischemia in rats is induced by preconditioning with electroacupuncture: window of protection and the role of adenosine

The aim of the present study was to investigate the first protective window of preconditioning with electroacupuncture (EA) against focal cerebral ischemia, and to explore whether adenosine is involved in the rapid tolerance phenomenon. Sixty-four male Sprague-Dawley rats were randomly assigned to eight groups (n=8 in each). Animals in the control group received no treatment, and animals in EA1-EA4 groups received EA at 0.5, 1, 2 and 3 h before induction of focal cerebral ischemia, respectively. Rats in DPCPX group were intraperitoneally injected with 1 mg kg-1 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), 3 h before induction of focal cerebral ischemia. Animals in vehicle group and EA+DPCPX group were pretreated with 1 ml kg-1 dimethyl sulfoxide (DMSO, the solvent of DPCPX) and 1 mg kg-1 DPCPX 30 min before preconditioning with EA, respectively. All rats were anesthetized with 40 mg kg-1 pentobarbital sodium intraperitoneally. Animals that required EA preconditioning, received EA with intensity of 1 mA and frequency of 15 Hz at the Baihui acupoint (GV 20) for 30 min. The focal cerebral ischemia was produced by the right middle cerebral artery occlusion (MCAO) for 120 min. The neurologic deficit scores (NDS) and brain infarct volumes were evaluated at 24 h after reperfusion. All rats survived until 24 h after reperfusion. Preconditioning with EA at 2 h before induction of focal cerebral ischemia improved neurologic outcome (P<0.05 versus control) and reduced the infarct volume (P<0.01 versus control) at 24 h after reperfusion. These beneficial effects were reversed by pretreatment with 1 mg kg-1 DPCPX, whereas this agent itself did not affect the NDS and volume in drug-ischemic controls after ischemia. The results show that preconditioning with single EA session induces rapid tolerance to focal cerebral ischemia. The rapid ischemic tolerance appears at 2 h (but not at 0.5, 1, or 3 h) after preconditioning, and is possibly mediated through an adenosine A1 receptor-related mechanism.     

SIRT1对早期脑缺血大鼠水通道蛋白4表达的影响

目的:检测水通道蛋白4(AQP4)及沉默信息调节因子1(SIRT1)在脑缺血大鼠脑组织中的表达变化,探究SIRT1对AQP4的调节作用,明确二者在脑缺血及脑水肿发生发展中的作用。方法:雄性SD大鼠随机分成假手术组(sham组)和脑缺血模型组(MCAO组),其中MCAO组又分为6 h、12 h、24 h和48 h 4个时点组别。采用线栓法阻塞大脑中动脉建立局灶性脑缺血模型,于相应时点进行神经症状评分,Morris水迷宫检测大鼠学习认知功能,TTC染色观察脑梗死体积,干湿重法检测脑含水量的变化,HE染色观察大脑皮层周围组织神经细胞形态学变化,Western blot检测AQP4、SIRT1和基质金属蛋白酶9(MMP-9)的表达情况。结果:与sham组相比较,随着再灌注时间增加,MCAO组大鼠神经功能评分、脑梗死体积、脑组织通透性和脑组织含水量均持续增加,而大鼠学习认知功能则降低显著,HE染色显示脑缺血大脑皮层周围组织神经元细胞形态不规则,数目减少;Western blot实验结果显示AQP4表达水平呈增高趋势,SIRT1表达降低,MMP-9表达增高,MCAO-48 h组与sham组比较差异最明显(P0.01)。结论:脑缺血后,伴随脑组织损伤的加剧,SIRT1和MMP-9信号通路的表达激活影响了AQP4的表达活化,共同参与了脑水肿的形成。     

局灶性脑缺血预处理上调大鼠梗死区周围巢蛋白的表达

目的 观察局灶性脑缺血预处理(IP)对巢蛋白(NESTIN)表达的影响,探讨NESTIN与脑缺血耐受(BIT)的关系及可能的内源性神经保护机制.方法 45只SD雄性大鼠随机分为脑缺血预处理(CIP)组、大脑中动脉阻塞(MCAO)组、假手术(sham)组.采用TTC染色测定脑梗死体积,光镜下观察脑组织病理改变,免疫组织化...