变构促红细胞生成素对中年雌性脑缺血小鼠白质损伤的作用研究

目的 研究变构促红细胞生成素(MEPO)对成年雌性脑缺血小鼠白质的保护作用.方法 将30只成年雌性C57BL/6J小鼠按随机数字表法完全随机分为3组:假手术组(Sham组),脑缺血模型组(Vehicle组)及脑缺血MEPO治疗组(MEPO组),每组10只.采用大脑中动脉远端血管永久性闭塞的方式制备小鼠脑缺血模型.MEP...     

Minimally invasive neuroradiologic model of preclinical transient middle cerebral artery occlusion in canines

Stroke is currently the third leading cause of death in the United States, with approximately 780,000 Americans affected by a new or recurring stroke each year. Although a variety of therapeutic approaches have shown promise in small-animal models of stroke, the vast majority of clinical trials to test the efficacy of such modalities have failed. To bridge the translational gap between laboratory and clinical research, we developed a preclinical model of acute ischemic stroke in dogs. Using a minimally invasive endovascular approach, a platinum coil was intravascularly guided through the vertebrobasilar system under C-arm fluoroscopy to occlude the M1 segment of the middle cerebral artery (MCA) for 1 h. The approach included femoral artery catheterization to access the MCA and therefore eliminated the occurrence of head trauma associated with other preclinical stroke models relying on transorbital or craniectomy approaches. After 1 h of focal MCA ischemia, the coil was retrieved to cause reperfusion, which was verified by arteriograms. At 24 h, T2-weighted coronal magnetic resonance (MR) images were acquired and processed for three-dimensional reconstruction of the brain and its vasculature. Infarction, limited to the area at risk, was noted. Two independent observers calculated the mean percentage hemispherical lesion volumes as follows: observer 1, 30.9 ± 2.1%; observer 2, 31.2 ± 4.3%. Infarct-affected changes in histology were determined by hematoxylin and eosin as well as by Fluoro-Jade staining. This work reports the successful development of a powerful preclinical model of stroke that lends itself to the study of biologic mechanisms as well as to testing experimental therapeutics.     

马来酸桂哌齐特对大脑中动脉缺血再灌注小鼠的脑保护作用及神经生长相关蛋白43早期表达的影响

目的 探讨马来酸桂哌齐特(CM)对大脑中动脉缺血再灌注(tMCAO)小鼠的脑保护作用及脑组织中神经生长相关蛋白43(GAP-43)的影响.方法 32只ICR小鼠随机分为正常组、假手术组、缺血2小时再灌注模型组(tMCAO)和马来酸桂哌齐特组(CM).应用线栓法制备大脑中tMCAO模型,腹腔注射CM建立CM组,48小时后观察不同组间小鼠行为学的差异,利用苏木素-伊红(HE)染色法检测小鼠脑组织的病理变化并计算梗死体积,利用尼氏染色法检测尼氏小体的变化,利用免疫荧光染色法检测Caspase-3和GAP-43的表达.结果 正常组及假手术组小鼠无异常行为变化,tMCAO组出现明显神经损伤性异常行为;与正常组及假手术组相比,tMCAO组脑组织出现严重病理变化,脑梗死体积增大,尼氏小体减少,Caspase-3和GAP-43的表达水平明显增高.CM组与tMCAO组比较,神经功能缺损程度明显减轻(P＜0.05),梗死体积减小(P＜0.01),尼氏小体多,Caspase-3和GAP-43的表达水平下降.结论 CM对tMCAO小鼠的脑损伤有一定的保护效果,GAP-43可能在缺血再灌注损伤早期以及CM药理作用中发挥与损伤应答相关的重要作用.     

小鼠大脑中动脉缺血后海马星形胶质细胞变化的研究

目的观察小鼠大脑中动脉缺血后海马星形胶质细胞的动态改变。方法昆明小鼠64只随机分为脑缺血组48只、正常组4只和假手术组12只。脑缺血组用线栓法制作小鼠右侧大脑中动脉缺血模型;TTC染色观察缺血1、3、6、12、24和48h的脑缺血部位及范围;HE染色法观察不同缺血时间海马神经元的变化;用免疫组织化学方法观察不同缺血时间海马星形胶质细胞胶质纤维酸性蛋白(GFAP)表达的变化。结果与正常组比较,脑缺血组3、6、12、24和48h脑梗死体积显著增加[(19.67±5.46)%,(33.68±3.46)%,(54.65±6.13)%,(76.85±7.15)%,(81.81±4.09)%,P=0.000]。HE染色显示,脑缺血组缺血侧海马神经元产生损伤并不断加重,缺血6h后出现不可逆性损伤。与正常组及假手术组相比,脑缺血组缺血侧海马各区GFAP表达随缺血时间的延长数量不断增多(P0.05),细胞体肿胀,突起不断增粗延长,GFAP阳性细胞增长在6h时增速最快,48h达到高峰(P0.05)。结论小鼠大脑中动脉缺血后,可引起缺血侧海马神经元损伤,并刺激星形胶质细胞过度反应和增殖。     

转基因小鼠bcl-xl过表达在大脑中动脉栓塞中的保护作用及机制

目的观察探讨大脑中动脉栓塞模型转基因小鼠中bcl—xl的过表达对脑缺血及缺血后再灌注是否具有保护作用及其作用机制。方法建立bcl—xl过表达转基因小鼠，将该模型小鼠与同种系野生型小鼠同时行线栓永久性阻塞大脑中动脉，在缺血24h时测其神经功能评分，观察转基因小鼠与野生型小鼠的差别。在缺血后不同时间点分别检测两种小鼠脑梗死体积及其动态变化，比较其脑组织中bcl—xl的表达量的差异、再灌注时凋亡细胞的数量和分布情况及脑中细胞色素C的表达量。结果转基因小鼠的神经功能评分低于野生型小鼠。在缺血后不同时间点转基因小鼠的梗死体积、缺血局部细胞色素C的表达、皮质缺血区内的凋亡细胞数明显少于野生型小鼠，且保护作用发生时间旱，持续时间较长。梗死前后转基因小鼠的皮质细胞bcl—xl的表达量均明显高于野生型小鼠，且梗死后两种小鼠体内的bcl—xl的表达量均有所增加，但二者之间差异无统计学意义（P〉0．05）。结论转基因小鼠中bcl—xl的过表达能降低脑梗死的体积并改善小鼠的神经功能，这种效应可能是通过抑制细胞凋亡而实现的，其机制可能是bcl—xl的过表达抑制了细胞色素C的释放。     

High NaCl predisposes Dahl rats to cerebral infarction after middle cerebral artery occlusion

High (8%) and low (0.3%) NaCl diets were administered for 3 weeks before testing inbred Dahl salt-sensitive (SS/Jr) or salt-resistant rats (SR/Jr) for altered susceptibility to cerebral infarction after occlusion of the middle cerebral artery. At occlusion time, mean systolic blood pressure (BP) was 201 +/- 7 mm Hg in SS/Jr fed a high NaCl diet. Two weeks later an atrophied infarct was present in the territory of the occluded artery of all (n = 10) hypertensive SS/Jr, and infarct size was correlated with BP at occlusion time (p less than 0.01). In normotensive control SS/Jr fed a low NaCl diet (n = 11), BP (118 +/- 3 mm Hg), frequency of infarction (18%), and infarct size were all significantly less (p less than 0.05) than in the hypertensive rats. In SR/Jr fed a high (n = 11) or low (n = 10) NaCl diet, BP was not statistically different (112 +/- 4 vs 116 +/- 4 mm Hg). Cerebral infarction frequency was significantly (p less than 0.05) greater in SR/Jr fed a high NaCl diet (73%) than in SR/Jr receiving a low NaCl diet (20%), but infarct size was not correlated with BP in SR/Jr (p greater than 0.05). Thus, elevated NaCl intake in SS/Jr and SR/Jr before middle cerebral artery occlusion predisposes to cerebral infarction, but differences in infarct size and its correlation with BP suggest the controlling factors are not identical in the two strains.     

Effects of blockade of cerebral lymphatic drainage on cerebral ischemia after middle cerebral artery occlusion in rats

This experiment aimed to investigate the effects of blockade of cerebral lymphatic drainage on cerebral ischemic damage. Seventy six Wistar rats were divided randomly into middle cerebral artery occlusion (MCAO) group and MCAO plus cerebral lymphatic blockade (MCAO+CLB) group for the experiment. The contents of water and electrolytes, the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in the ischemic brain tissue were detected at 24, 48 and 72 hours after the operation. The morphologic examination was also performed. In MCAO group, contents of water, sodium and calcium in the ischemic brain tissue increased significantly at any time after the operation. The SOD activity decreased while the MDA content increased markedly. The morphologic findings showed severe damage of ischemic brain tissue and neurons. In MCAO+CLB group, the above parameters were altered more obviously. The present observation suggests that blockade of cerebral lymphatic drainage may deteriorate ischemic brain damage after MCAO.     

小鼠大脑中动脉梗死模型VERGE 蛋白表达的变化及其机制

;两组MCAO模型非梗死侧的VERGE、p-JNK2、p-ERK1/2、P-38蛋白表达均无变化.结论 VERGE 蛋白表达在小鼠MCAO的早期明显升高可能与JNK2通路有关而与ERK、P38通路无关.     

改良大鼠大脑中动脉阻塞模型的建立

目的建立稳定、可靠的大鼠大脑中动脉阻塞(MCAO)改良模型。方法将60只SD雄性大鼠随机分为实验组和对照组,每组30只。实验组采用改良方法制作MCAO模型;对照组采用Longa传统方法制作模型。比较两组模型制作的成功率、脑梗死体积及模型稳定性。结果改良后的大鼠MCAO模型制作成功率和脑梗死体积分别为82·8%、(46±7)%,与对照组的89·3%、(48±7)%比较,差异无显著性(P>0·05)。实验组脑梗死体积变异系数为15·94%,对照组为16·21%,两组的模型稳定性相近。结论改良的大鼠MCAO模型是一种稳定性好、成功率高的脑缺血-再灌注模型。     

Effect of age in rats following middle cerebral artery occlusion

BACKGROUND: Despite the impressive increased understanding of the ischemic brain damage in general, the study of effects on different age groups, young versus old, using comparable ischemic insults is clearly lacking. OBJECTIVES: To investigate the mortality rate and neurological outcome among young and old rats, through a model of cerebral ischemia by middle cerebral artery occlusion (MCAO). METHODS: Twenty-three old (22-24 months of age) and 16 young (3-4 months of age) male rats underwent a MCAO procedure for 60 min. Surviving rats were randomly assigned to the 24-hour or 28-day resting group. The mortality rate and neurological outcome in different recovery time periods were determined for comparison between the young and old rats. RESULTS: The overall mortality rate in old rats (43.5%) was significantly higher than that of the young rats (6.3%) (p = 0.01). The infarct volume for the 24-hour post-MCAO was 181.86 +/- 11.87 mm(3) for the young rats, and 204.64 +/- 27.18 mm(3) for the old rats. For the 28-day post-MCAO, the value was 91.16 +/- 3.59 mm(3) for the young rats, and 103.38 +/- 26.43 mm(3) for the old rats. A significant reduction in infarct volume is noted in both young (p < 0.01) and old (p < 0.05) rats after 28 days of recovery compared to that after 24 h of recovery. There was no meaningful difference in infarct volume between the young and old rats measured at 24 h or 28 days after the ischemic procedure. The right volume was larger than the left volume at 24 h post-MCAO for both the young and the old rats, whereas the quotient approached unity for the young rats at 28 days post-MCAO. For the old rats, the quotient was negative at 28 days post-MCAO, representing the ipsilateral hemisphere was smaller than the contralateral hemisphere. CONCLUSION: The mortality risk to ischemic damage is greater for old rats. If an old rat survives the high-risk mortality in a short period after the MCAO procedure, the recovery would be of no difference to that of a young rat.     

脑梗死后脑红蛋白的表达及其保护机制

目的探讨脑梗死后缺血半暗带脑组织中脑红蛋白（NGB）表达与caspase-3、谷氨酸表达的关系及NGB在脑缺血中的表达规律和保护作用的机制。方法制作大鼠局灶性脑缺血模型（MCAO）,随机分为假手术对照组、脑缺血组和单克隆NGB抗体干预组、干预对照组、正常干预对照组,分别在不同时间点断头取脑,制作标本,作脑红蛋白、caspase-3和谷氨酸免疫组化染色。结果（1）与假手术对照组比较,缺血5min亚组可见NGB阳性细胞数开始上升,0.5h达到高峰（P〈0.01）,随后下降,至6h接近假手术组。缺血各组（除24h、72h外）之间两两比较,差异均有统计学意义（P〈0.01）;（2）与假手术对照组比较,缺血0.5h亚组大脑皮质与豆状核区细胞caspase-3阳性表达增多,6～24h达到高峰（P〈0.01）,72h时仍高于假手术对照组,缺血各亚组之间两两比较,差异均有统计学意义（P〈0.01）;（3）与假手术对照组比较,缺血各亚组大脑皮质与豆状核区细胞谷氨酸阳性表达缺血0.5h就已增多,且随时间的变化呈逐步增高的趋势,24～72h达到高峰（P〈0.01）,缺血各亚组之间两两比较,差异均有统计学意义（P〈0.01）;（4）NGB表达与caspase-3、谷氨酸表达均呈负相关关系（分别为r=-0.953,P〈0.01;r=-0.973,P〈0.01）;（5）干预对照组caspase-3、谷氨酸表达均上调（P〈0.01）。结论脑缺血后NGB在缺血周围半暗带区早期表达升高,随后下降,于6h后降至正常,具有调节caspase-3、谷氨酸表达的作用,这是NGB脑保护作用的可能机制。     

雌激素对小鼠大脑中动脉缺血后海马星形胶质细胞变化的研究

目的探讨雌激素对小鼠大脑中动脉缺血后海马星形胶质细胞动态变化的影响。方法雄性昆明小鼠108只随机分为雌激素组(术前7d按体质量0.1ml/10g每日定时腹腔注射17β雌二醇)54只和对照组(腹腔注射生理盐水)54只,2组均行永久性右侧大脑中动脉阻塞(MCAO)术,分别于MCAO术后3、6、12、24、48和72h取材,TTC染色法观察2组小鼠脑缺血部位及范围;苏木精-伊红染色观察海马神经元的变化;免疫组织化学法观察海马星形胶质细胞胶质纤维酸性蛋白(GFAP)表达变化。结果雌激素组术后各时间点脑梗死体积明显低于对照组(P0.05,P0.01),以缺血12h最为明显[(31.50±3.36)%vs (54.50±5.68)%,P=0.019]。2组海马神经元损伤程度随缺血时间的延长而加重,且相同时间点,雌激素组缺血侧海马神经元损伤程度均较对照组轻。2组双侧海马各区GFAP阳性细胞表达均随缺血时间延长而增多(P0.05);除CA3区缺血6h时,雌激素组缺血侧GFAP阳性细胞表达均较对照组增多(P0.05),突触增粗延长,树突棘分布较密集。结论雌激素对小鼠局灶性脑缺血具有神经保护作用,可刺激星形胶质细胞突触的发生,减轻缺血后神经元损伤,从而减小脑梗死体积。     

Percutaneous transluminal angioplasty in an embolic middle cerebral artery occlusion

A young lady developed left middle cerebral artery embolism after percutaneous transseptal mitral commissurotomy. She was successfully treated with immediate percutaneous transluminal angioplasty. There was complete recovery of neurological deficit.     

大脑中动脉高密度征与磁敏感血管征对大脑中动脉闭塞评估的一致性

目的探讨CT平扫大脑中动脉高密度征(HMCAS)与磁敏感加权成像大脑中动脉(MCA)磁敏感血管征(SVS)的一致性。方法回顾性连续纳入150例发病6 h内前循环脑梗死急性期患者,均接受头部CT、MRI一站式检查,并记录患者基线情况。对CT及MRI进行分析,记录HMCAS、SVS存在情况,共有75例与DSA结果进行对照;HMCAS与SVS的一致性采用Kappa检验并行假设u检验。结果以DSA为参照标准,HMCAS和SVS对急性MCA主干闭塞的敏感度、特异度分别为42.4%(14/33)、36.4%(12/33)和92.9%(39/42)、90.5%(38/42);HMCAS与SVS的一致性检验值κ=0.804,u值为9.570(P0.05)。结论 MCA的HMCAS与SVS呈高度一致性,可为急性缺血性卒中的早期诊断、治疗方式的选择及溶栓后血管再通预测提供参考依据。     

Inhibition of matrix metalloproteinase-9 activity by trandolapril after middle cerebral artery occlusion in rats.

We investigated whether an angiotensin-converting enzyme (ACE) inhibitor could inhibit matrix metalloproteinase (MMP) activities in cerebral infarct lesions after middle cerebral artery occlusion (MCAO) in rats. After placebo or trandolapril (5 mg/kg per day) was administered orally for 7 days, we permanently occluded the right middle cerebral artery. ACE activity in extracts from the infarct side of placebo-treated rats was significantly higher than that in extracts from the non-infarct side from 5 days after MCAO, though they did not differ at 1 day. ACE activities in extracts from both hemispheric segments in the trandolapril-treated group were significantly decreased compared with those in the placebo-treated group before MCAO, and this significant reduction persisted even at 7 days after MCAO. In the placebo-treated group, MMP-9 and MMP-2 activities in the infarct side were significantly increased at 12 h and at 1 day after MCAO, respectively. Trandolapril treatment significantly reduced MMP-9 and MMP-2 activities to 68.5% and 53.2%, respectively. Seven days after MCAO, the ratios of infarct areas to the hemispheric sectional areas in placebo- and trandolapril-treated rats were 55.4+/-2.1% and 30.9+/-2.9%, respectively, and this difference was significant. Neurological severity scores were significantly improved from 1 to 7 days after MCAO in trandolapril-treated rats. Cumulative survival in trandolapril-treated rats was significantly increased compared with that in placebo-treated rats. Thus, the inhibition of MMP-9 by trandolapril might be part of the mechanism that prevents cerebral damage after cerebral ischemia.     

Therapy with recombinant T-cell receptor ligand reduces infarct size and infiltrating inflammatory cells in brain after middle cerebral artery occlusion in mice

Stroke induces a biphasic effect on the peripheral immune response that involves early activation of peripheral leukocytes followed by severe immunosuppression and atrophy of the spleen. Peripheral immune cells, including T lymphocytes, migrate to the brain and exacerbate the developing infarct. Recombinant T-cell receptor (TCR) Ligand (RTL)551 is designed as a partial TCR agonist for myelin oligodendrocyte glycoprotein (MOG)-reactive T cells and has demonstrated the capacity to limit infarct volume and inflammation in brain when administered to mice undergoing middle cerebral artery occlusion (MCAO). The goal of this study was to determine if RTL551 could retain protection when given within the therapeutically relevant 4 h time window currently in clinical practice for stroke patients. RTL551 was administered subcutaneously 4 h after MCAO, with repeated doses every 24 h until the time of euthanasia. Cell numbers were assessed in the brain, blood, spleen and lymph nodes and infarct size was measured after 24 and 96 h reperfusion. RTL551 reduced infarct size in both cortex and striatum at 24 h and in cortex at 96 h after MCAO and inhibited the accumulation of inflammatory cells in brain at both time points. At 24 h post-MCAO, RTL551 reduced the frequency of the activation marker, CD44, on T-cells in blood and in the ischemic hemisphere. Moreover, RTL551 reduced expression of the chemokine receptors, CCR5 in lymph nodes and spleen, and CCR7 in the blood and lymph nodes. These data demonstrate effective treatment of experimental stroke with RTL551 within a therapeutically relevant 4 h time window through immune regulation of myelin-reactive inflammatory T-cells.     

Neuronal loss and gliosis in the rat striatum subjected to 15 and 30 minutes of middle cerebral artery occlusion

Selective neuronal death or loss in certain brain regions has been well characterized in animal models of transient global cerebral ischemia. However, selective neuronal death in transient focal cerebral ischemia needs more investigation. Therefore, in this study, we studied selective neuronal death in the striatum (caudate putamen) of rats subjected to 15 or 30 min middle cerebral artery occlusion (MCAO). Neuronal death occurred in the dorsolateral field, not in the medial field in 30 min, not 15 min, MCAO-operated rats 5 days after MCAO using neuronal nuclear antigen immunohistochemistry and Fluoro-Jade B histofluorescence staining. In this group, immunoreactivity of glial fibrillary acidic protein in astrocytes was hardly shown in the dorsolateral field, although the immunoreactivity increased in the medial field. In addition, immunoreactivity of ionized calcium binding adapter molecule 1 in microglia was dramatically increased in the dorsolateral, not in the medial, field only in 30 min MCAO-operated rats. Briefly, these results show that at least 30 min of MCAO can evoke selective neuronal death, astrocytic dysfunction and microglial activation in the dorsolateral field of the rat striatum and suggest that a rat model of 30 min MCAO can be used to investigate mechanisms of neuronal death and gliosis following brief transient focal cerebral ischemic events for acute transient ischemic attack.