大鼠大脑中动脉缺血和再灌注后环氧合酶-2mRNA表达的研究

目的研究大鼠大脑中动脉缺血和再灌注模型中环氧合酶－２（ＣＯＸ－２）基因的表达。方法原位杂交方法。结果缺血３０ｍｉｎ再灌注组,血流再通４ｈ后缺血区的大脑皮层有很强的表达并持续２４ｈ。缺血９０ｍｉｎ再灌注组和持续缺血组在缺血区以外的广泛大脑皮层显著表达,在海马的齿状回两侧及纹状体也发现表达。ＣＯＸ－２ｍＲＮＡ的表达可被ＭＫ－８０１抑制。而ＮＢＱＸ和倍他米松对其表达没有影响。结论在缺血区、缺血周边部、缺血远隔区有ＮＭＤＡ受体介导的ＣＯＸ－２表达,阐明上述区域花生四烯酸代谢活性化     

巴曲酶对局灶性脑缺血再灌流大鼠成纤维细胞生长因子样免疫…

以往实验研究曾发现巴曲酶对脑血管病具有良好的神经保护作用，本文研究的目的为：巴曲酶是否还通过影响成纤维细胞生长因子起修复作用，用大鼠中大脑动脉（ＭＣＡ）线栓法脑缺血再灌注模型及免疫组化方法发现在缺血９０ｍｉｎ再灌流４８ｈ后，缺血侧皮层，尾壳核及海马区ｂＦＧＦ样免疫反应细胞增加及神经细胞变性，在缺血后给予巴曲酶（８ＢＵ／ｋｇ），ｂＦＧＦ样免疫反应加强，并且缺血对侧相应ＭＣＡ供血脑区也可见轻度的ｂＦＧ     

巴曲酶对局灶性脑缺血及缺血再灌注的神经保护作用：光镜…

本实验采用大鼠大脑中动脉线检法，观察巴曲酶对缺血再灌注的影响。共１５只。６只缺血９０ｍｉｎ，再灌注９０ｍｉｎ；６只连续缺血１８０ｍｉｎ。该行组６只大鼠又分为巴曲酶组，术前３０ｍｉｎ给予巴曲酶（８ＢＵ／ｋｇ，ＩＰ），另一组为盐水组，给予等容生理盐水。３只为假手术组，也仅予术前给等容盐水。各组均手术后１８０ｍｉｎ，断头取脑，用光镜（定性及定量）及电镜观察了大脑皮层及ＣＡ１区的病理变化。结果：巴曲酶组较     

巴曲酶对局灶性脑缺血再灌流大鼠成纤维细胞生长因子样免疫反应的影响

以往实验研究曾发现巴曲酶对脑血管病具有良好的神经保护作用。本文研究的目的为：巴曲酶是否还通过影响成纤维细胞生长因子起修复作用。用大鼠中大脑动脉（ＭＣＡ）线栓法脑缺血再灌注模型及免疫组化方法发现在缺血９０ｍｉｎ，再灌流４８ｈ后，缺血侧皮层、尾壳核及海马区ｂＦＧＦ样免疫反应细胞增加及神经细胞变性。在缺血后给予巴曲酶（８ＢＵ／ｋｇ），ｂＦＧＦ样免疫反应加强，并且缺血对侧相应ＭＣＡ供血脑区也可见轻度的ｂＦＧＦ样免疫反应改变，神经细胞变性之程度较轻。提示：巴曲酶对脑缺血再灌注的保护作用可能与它加强ｂＦＧＦ的修复作用有关。     

巴曲酶对局灶性脑缺血及缺血再灌注的神经保护作用:光镜定性定量和超微结构观察

本实验采用大鼠大脑中动脉线检法，观察巴曲酶对缺血再灌注的影响。共１５只。６只缺血９０ｍｉｎ，再灌注９０ｍｉｎ；６只连续缺血１８０ｍｉｎ。该各组６只大鼠又分为巴曲酶组，术前３０ｍｉｎ给予巴曲酶（８ＢＵ／ｋｇ，ＩＰ），另一组为盐水组，给予等容生理盐水。３只为假手术组，也仅予术前给等容盐水。各组均手术后１８０ｍｉｎ，断头取脑，用光镜（定性及定量）及电镜观察了大脑皮层及ＣＡ１区的病理变化。结果：巴曲酶组较盐水组正常神经元数量显著多，缺血性损伤程度较轻。     

局灶性缺血再灌注时丹参对热休克蛋白70的影响—免疫细胞化学及…

丹参素以活血化瘀称著，常用于治疗缺血性脑血管病，热休克蛋白７０（ＨＳＰ７０）具神经保护作用。本文研究目的：丹参是否也通过影响ＨＳＰ７０起作用，采用大鼠犬脑中动脉（ＭＣＡ）线检模型。以免疫细胞化学及病理组织方法在同一动物中进行研究。结果发现在缺血９０ｍｉｎ再灌注２４ｈ后，对照组手术侧皮层ＨＳＰ７０免疫反应增强及皮层神经细胞有缺血性损伤，而丹参组（缺血９０ｍｉｎ时给予丹参１０ｇ／Ｋｇ，体重ｉｐ），则Ｈ     

神经节苷脂GM1拮抗剂对海马CA1区缺血神经元形态结构变化影 …

实验观察了神经节苷脂ＧＭ１拮抗剂－霍乱毒素对应激性高血压大鼠海马脑片体外人工缺血３０、６０、１２０ｍｉｎＣＡ１区神经元形态结构的影响。缺血３０ｍｉｎ时胞体变小，胞内小空泡形成，细胞器减少，少量的线粒体和内质网肿胀。核不规则，染色质分布不均，出现边集。随缺血时间的延长胞内细胞器破碎，残存细胞器结构不清，胞核固缩，部分裂解。而霍乱毒素则加重缺血３０、６０、１２０ｍｉｎＣＡ１区神经元形态学上的改变，具有     

神经节苷脂GM_1拮抗剂对海马CA_1区缺血神经元形态结构变化影响的离体研究

实验观察了神经节苷脂ＧＭ１拮抗剂——霍乱毒素对应激性高血压大鼠海马脑片体外人工缺血３０、６０、１２０ｍｉｎＣＡ１区神经元形态结构的影响。缺血３０ｍｉｎ时胞体变小，胞内小空泡形成，细胞器减少，少量的线粒体和内质网肿胀。核不规则，染色质分布不均，出现边集。随缺血时间的延长胞内细胞器破碎，残存细胞器结构不清，胞核固缩，部分裂解。而霍乱毒素则加重缺血３０、６０、１２０ｍｉｎＣＡ１区神经元形态学上的改变，具有明显的神经元损害作用。     

用逆转录-多聚酶链反应检测局灶脑缺血及再灌注后c-fos和c-jun基因表达

本研究应用逆转录－多聚酶链反应（ＲＴ－ＰＣＲ）方法检测大鼠局灶脑缺血模型中即早基因ｃ－ｆｏｓ和ｃ－ｊｕｎ的表达。结果发现缺血１５ｍｉｎ时可见到ｃ－ｆｏｓ和ｃ－ｊｕｎｍＲＮＡ表达缺血３０ｍｉｎ时引起轻微左侧局灶脑缺血改变，可诱导左侧局灶脑缺血区ｃ－ｆｏｓ和ｃ－ｊｕｎｍＲＮＡ广泛的表达；缺血９０ｍｉｎ后，导致大面积局灶脑缺血改变，诱导上述两种基因在同侧缺血区与同侧非大脑中动脉（ＭＣＡ）供血区的海马中表达。后者有相当轻的缺血症状。再灌流６０ｍｉｎ后诱导两种基因的共同表达立即达高峰。我们采用标准化的大鼠局灶脑缺血及再灌注模型，在分子水平上动态观察缺血／再灌注后基因变化特征，为缺血性脑损害的防治提供实验依据。     

反复性脑缺血大脑皮质LTC_4、cAMP和OFR的代谢变化

目的：研究反复脑缺血大脑皮质白三烯（ＬＴＣ４）、环腺苷酸（ｃＡＭＰ）和氧自由基（ＯＦＲ）的代谢变化与神经元损伤的关系。方法：对比观察大鼠反复性与单次性脑缺血大脑皮质ＬＴＣ４、ｃＡＭＰ、超氧化物歧化酶（ＳＯＤ）和丙二醛（ＭＤＡ）的含量变化及相应的病理改变。结果：反复缺血及再灌流早期ＬＴＣ１、ｃＡＭＰ的含量明显升高,ＳＯＤ活性显著降低,ＭＤＡ延迟性持续显著增高,皮质神经元损害显著重于单次缺血组。结论：ＬＴＣ４、ｃＡＭＰ和 ＯＦＲ均参与了反复缺血性脑损害的病理机制,可能与 Ｃａ＋＋介导的花生四烯酸（ＡＡ）瀑布效应有关。     

Ischemic preconditioning procedure induces behavioral deficits in the absence of brain injury?

Preconditioning describes a phenomenon whereby a sub-injury inducing insult can protect against a later larger injury. Thus, short-term cerebral ischemia can protect against a prolonged ischemia (ischemic preconditioning). This study examines rats undergoing ischemic preconditioning to test whether preconditioning may cause changes in behavior even though they do not cause an identifiable brain lesion. Rats had a transient (15 minutes) middle cerebral artery occlusion or a sham occlusion. Forelimb placing and forelimb use asymmetry tests were used to assess behavioral deficits. Brain histology, microglia activation, heat shock protein and ferritin levels were also examined. Ischemic preconditioning did not cause brain infarction, but induced behavioral changes. There were no significant differences between ischemic preconditioning and sham rats in the two behavioral tests at day one. However, the ischemic preconditioning group showed impaired forelimb placing at days 3, 7 and 14 (p<0.05). That group also had a significant (p<0.05) behavioral deficit in the forelimb use asymmetry test at days 3 and 7 (but not 14). Our present study demonstrated that a behavioral deficit occurred in ischemic preconditioning. This raises the question of whether induction of protective mechanisms by preconditioning stimuli necessarily involves some form of brain injury, detectable by changes in behavior though not by a lesion. This would be consistent with data suggesting that brain injury can initiate mechanisms potentially favorable to neuroplasticity and neuroprotection.     

局灶性缺血预处理对脑缺血大鼠血管内皮生长因子表达及血管形成的影响

目的：探讨血管内皮生长因子（VEGF）在脑缺血耐受中的作用及其与血管形成的关系。方法：Wistar大鼠线栓法阻塞大脑中动脉建立局灶性缺血预处理模型,并进行神经功能评分。随机分为假手术（对照组）、非缺血预处理（NIP）组和缺血预处理（IP）组,NIP和IP组再根据不同时间窗随机分成5个亚组。分别在缺血预处理后1、3、7、14和21 d进行再次缺血2 h再灌注22 h,然后取脑检测：TTC染色测定脑梗死体积,计数微血管密度,免疫组化检测CD34和VEGF蛋白表达,原位杂交法检测VEGF mRNA表达。结果：①组间比较：IP 1、3和7 d亚组脑梗死体积较NIP组明显减小（P〈0.01）,其神经行为缺损评分也明显降低（P〈0.05）;IP 3和7 d亚组脑微血管密度明显增高（P〈0.05）;IP 1、3和7 d亚组VEGF蛋白及mRNA表达明显增高（P〈0.05,P〈0.01）。②组内比较：IP 7 d亚组微血管在缺血灶周边区分布最为密集,脑微血管密度明显高于同组内其他亚组（P〈0.05）;IP 3和7 d亚组VEGF蛋白表达明显增高,VEGF mRNA表达在IP 1 d即开始升高,高峰出现在IP 3 d,持续至7 d。结论：缺血预处理诱导了脑缺血耐受,缺血预处理诱导的VEGF表达增加以及血管形成在脑缺血耐受中发挥重要作用。     

Neurotrophic factor expression after focal brain ischemia preceded by different preconditioning strategies

BACKGROUND: Both prolonged brain ischemia and preconditioning (PC) induce expression of neurotrophic factors. However, the influence of PC on their expression after a long-term ischemia remains vague. Previously, we have found various effects of PC on mRNA levels of different cytokines after focal brain ischemia. Thus, we investigated mRNA expression of nerve growth factor, brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor after 90-min middle cerebral artery occlusion (MCAo) preceded by ischemic or chemical PC. METHODS: MCAo was induced in rats using the suture method. PC had been carried out 3 days earlier. There were 4 experimental groups: MCAo alone; ischemic PC and MCAo; chemical PC and MCAo, and sham-operated rats. Expression of mRNAs in the ipsi- and contralateral cortex was studied by semiquantitative RT-PCR at 12 and 24 h after MCAo. RESULTS: Despite clearly neuroprotective effects of both PC strategies, mRNA levels of neurotrophic factors were similar in tolerant and nontolerant rats. Only BDNF mRNA expression, 12 h after reperfusion, was lower when ischemic PC was applied prior to long-term ischemia. CONCLUSIONS: These results suggest that PC generally does not change the expression of neurotrophic factor expression after a long-term focal brain ischemia compared to the nontolerant state.     

Induction of NADPH-diaphorase activity in the hippocampus in a rat model of cerebral ischemia and ischemic tolerance

Preconditioning of the brain with sublethal ischemia induces tolerance to subsequent lethal periods of ischemia (ischemic tolerance). In this study, we used NADPH-diaphorase histochemistry to investigate the postischemic changes of nitric oxide synthase (NOS) in the hippocampus in a rat model of cerebral ischemia and ischemic tolerance. Forebrain ischemia was induced by 4-vessel occlusion for 3 min as an ischemic preconditioning. Three days after the preconditioning or sham operation, second ischemia was induced for 6 min. A transient increase in NADPH-diaphorase activity, beginning after 2 h and maximal after 1 day, was observed in CA1 pyramidal neurons of rats subjected to 3 min of preconditioning ischemia as well as 6 min of subsequent ischemia both with and without preconditioning. In addition, expression of NADPH-diaphorase activity was seen in reactive glial cells in the damaged CA1 region of animals subjected to 6 min of ischemia without preconditioning. Thus, direct involvement of increased NADPH-diaphorase activity in ischemic tolerance was not suggested because the increased NADPH-diaphorase activity preceded the induction of ischemic tolerance which takes place 1–7 days after preconditioning. However, the present findings suggest that the induction of neuronal NADPH-diaphorase activity occurs in response to cerebral ischemia.     

Influence of chemical and ischemic preconditioning on cytokine expression after focal brain ischemia

Inflammation, upregulation of cytokines, proapoptotic molecules, and apoptosis are accepted widely as crucial players in stroke-induced brain damage. Induction of brain tolerance against ischemia by pretreatment with nonlethal stressors (preconditioning) has been found to influence expression of different molecules, in addition to reduction of infarct size. It remains unclear, however, whether and how preconditioning changes expression of cytokines after subsequent brain ischemia. We sought to analyze cortical expression of interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, Fas, and Fas ligand (FasL) mRNA after a transient, focal brain ischemia in rats subjected to preconditioning. The mRNA levels were determined using a semiquantitative RT-PCR in the ischemic and contralateral cortex, separately. Transient ischemia was induced by 90-min middle cerebral artery occlusion (MCAo) and neurologic deficits as well as infarct size were quantified. Preconditioning was carried out by a short-term MCAo or an injection of 3-nitropropionic acid 3 days before MCAo. In both preconditioning paradigms, similar effects on investigated mRNA levels were observed. IL-1beta and IL-6 levels were decreased in tolerant rats compared to those in nontolerant ones. Changes in TNF-alpha, TGF-beta, and Fas levels were comparable independently of tolerance state. FasL mRNA was at similar level in rats subjected to chemical preconditioning but lower after ischemic preconditioning. Our findings demonstrate that both preconditioning methods exert a very similar effect on the expression of investigated cytokines. Interestingly, we observed a selective effect of preconditioning on IL-1beta and IL-6 expression that suggests different functional properties as well as different regulation of analyzed molecules during an induction of the brain tolerance against ischemia.     

Ischemic preconditioning protects against ischemic brain injury

In this study, we hypothesized that an increase in integrin α_vβ_3 and its co-activator vascular endothelial growth factor play important neuroprotective roles in ischemic injury. We performed ischemic preconditioning with bilateral common carotid artery occlusion for 5 minutes in C57BL/6J mice. This was followed by ischemic injury with bilateral common carotid artery occlusion for 30 minutes. The time interval between ischemic preconditioning and lethal ischemia was 48 hours. Histopathological analysis showed that ischemic preconditioning substantially diminished damage to neurons in the hippocampus 7 days after ischemia. Evans Blue dye assay showed that ischemic preconditioning reduced damage to the blood-brain barrier 24 hours after ischemia. This demonstrates the neuroprotective effect of ischemic preconditioning. Western blot assay revealed a significant reduction in protein levels of integrin α_vβ_3, vascular endothelial growth factor and its receptor in mice given ischemic preconditioning compared with mice not given ischemic preconditioning 24 hours after ischemia. These findings suggest that the neuroprotective effect of ischemic preconditioning is associated with lower integrin α_vβ_3 and vascular endothelial growth factor levels in the brain following ischemia.     

Cycloheximide reduces infarct volume when administered up to 6 h after mild focal ischemia in rats

We have previously described a rodent model of brief (30 min) middle cerebral artery occlusion followed by reperfusion, in which infarction develops gradually, reaching completion more than 3 days after ischemia, accompanied by morphological, biochemical, and pharmacological evidence of apoptosis. In the present study, we tested the hypotheses that delayed administration of a protein synthesis inhibitor would be effective in reducing tissue injury in this slowly evolving ischemic infarction, and that efficacy of this treatment would wane with more prolonged ischemia. Focal cerebral ischemia was induced in Long-Evans rats by occlusion of the right middle cerebral artery. Infarction volume was analyzed using triphenyl tetrazolium chloride staining, and morphology was studied using hematoxylin and eosin stained sections. Following 30 min middle cerebral artery occlusion and reperfusion, the core ischemic region exhibited vacuolization in the neuropil by 36 h after ischemia, and infarction reached full size by 7 days after ischemia. Cycloheximide reduced infarct volume when given up to 6 h after ischemia. If the duration of ischemic insult was increased to 90 min, the therapeutic window for delayed cycloheximide was only 30 min. In permanent middle cerebral artery occlusion, cycloheximide was ineffective even when given prior to ischemia onset. After mild, but not severe, ischemic insults, cerebral infarction develops slowly and may be treatable with protein synthesis inhibitors, even when treatment is delayed for up to 6 h after the onset of ischemia.     

电针预处理对大鼠脑缺血再灌注损伤后EAAT2的表达研究

目的研究电针预处理对脑缺血再灌注损伤后大鼠缺血半暗带兴奋性谷氨酸转运体2(EAAT2)表达的影响,探讨EAAT2在电针预处理诱导脑缺血耐受中的作用。方法 18只SD雄性大鼠随机分为3组(n=6):分别为假手术(Sham)组、右侧大脑中动脉阻闭(MCAO)组、电针预处理(EA)组。假手术组仅分离血管,不进行阻闭,术后24 h检测;MCAO组用MCAO法致缺血120 min后于再灌注24 h检测;EA组大鼠予电针刺激30 min,刺激结束2 h后处理同MCAO组。3组大鼠在观察神经行为学变化后取材,通过2,3,5-氯化三苯四唑(TTC)染色评估梗死面积,并检测EAAT2 mRNA及蛋白表达水平。结果电针预处理能明显降低脑梗死容积百分比(P0.01),提高MCAO大鼠神经行为学评分,诱导脑缺血耐受并抑制脑缺血再灌注损伤后24 h EAAT2表达的下降(P0.01)。结论脑缺血再灌注损伤后,EAAT2表达下降,而电针预处理能显著抑制缺血半暗带EAAT2的表达下调,诱导脑缺血耐受,从而减轻脑缺血再灌注损伤。     

Extracellular signal-regulated kinase and c-Jun N-terminal protein kinase in ischemic tolerance.

The alterations and involvement of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal protein kinase (JNK) activation were examined in the hippocampal CA1 region in a rat model of global brain ischemic tolerance. Western blotting study showed that ERK activation (diphosphorylation) level was decreased (3.75-, 0.56-, and 0.23-fold vs sham control) and JNK activation level was increased (3.82-, 4.63-, and 5.30-fold vs sham control) 3 days after more severe ischemic insults (6 min, 8 min, and 10 min of ischemia, respectively). These alterations were significantly prevented by pretreatment with preconditioning ischemia, which also provided neuronal protection against ischemic injury. Inhibition of ERK activation after preconditioning ischemia by PD98059, a specific ERK kinase inhibitor, significantly prevented the inhibitory effects of preconditioning ischemia on both JNK activation and ischemic injury. The results suggest that ERK activation after preconditioning ischemia may result in the prevention of JNK activation and thus be involved in the protective responses in ischemic tolerance in hippocampal CA1 region.     

Similar neuroprotective effects of ischemic and hypoxic preconditioning on hypoxia–ischemia in the neonatal rat: A proton MRS study

The aim of this study was to evaluate the effect of ischemic and hypoxic preconditioning on hypoxia–ischemia (HI) in the neonatal rat. Seven-day-old Sprague-Dawley rats were divided into four groups: control, sham, ischemic preconditioning, and hypoxic preconditioning. Ischemic preconditioning with a 10-min occlusion of the right carotid artery and hypoxic preconditioning with 4-h of hypoxia (8% oxygen) were performed 24-h before HI. For HI, all rats underwent right carotid artery ligature, followed by 2.5-h of hypoxia. Proton magnetic resonance spectroscopy (¹H MRS) and TUNEL staining were evaluated at 1 and 7 days after HI. At 2 weeks after HI, all rats were sacrificed for morphological analysis. The lipid (Lip), N-acetyl aspartate (NAA), creatine (Cr), and choline-ratios were calculated and compared with TUNEL staining and brain morphologies. Both the ischemic and hypoxic preconditioning groups showed lower Lip/NAA and Lip/Cr ratios and morphological scores, and fewer TUNEL-positive cells than the control and sham groups (P < 0.05). There were no significant differences between the two preconditioning groups. In addition, the ratios correlated with the TUNEL staining and the degrees of morphological changes in all of the groups (P < 0.05). These results suggest that ischemic and hypoxic preconditioning in neonatal rats with HI similarly attenuate brain injury. Moreover, Lip/NAA and Lip/Cr ratios may be used as markers for assessing the extent of brain damage.