脑缺血再灌注后脑内脑源性神经营养因子的基因表达与调节

探讨：探讨脑缺血再灌注损伤后脑内脑源性神经营养因子（ＢＤＮＦ）ｍＲＡＮ水平的变化,推测ＢＤＮＦ对损伤病理的影响。方法线栓法制作大鼠脑缺血再灌注模,原位交检测大鼠海马神经元内ＢＤＮＦｍＲＮＡ,图像分析间接定量ＢＤＮＦｍＲＮＡ水平。结果（１）脑缺血及缺血再灌注均能诱导双侧海马神经元ＢＤＮＦｍＲＮＡ水平增高;（２）缺血损伤过重后海马神经元ＢＤＮＦｍＲＮＡ水平增高的程度反而小;（３）再灌注后ＢＤＮＦｍＲＮ     

针刺对缺血再灌注大鼠海马脑源性神经营养因子mRNA的影响

目的 探讨针刺对缺血再灌注大鼠海马内脑源性神经营养因子（BONF）基因表达的影响，推测针刺改善缺血再灌注的可能机制。方法 采用4-血管阴断法制备大鼠全脑缺血再灌注模型，电针刺激百会、肾俞、足三里穴后，利用RT-PCR检测BDNF mRNA。结果 正常组大鼠海马BDNF mRNA表达极低，缺血再灌注组大鼠海马BDNF mRNA表达明显增高，治疗15d的针刺1、2组大鼠海马BDNF mRNA表达较缺血再灌注组更高，及早治疗且治疗时间为20d的针刺3组大鼠海马BDNF mRNA表达较降低。结论 缺血再灌注大鼠海马BDNF水平增高有利于损伤的神经元存活、恢复；针刺促进脑内细胞分泌内源性BDNF可能是针刺有效治疗缺血再灌注的机制之一。     

大鼠脑缺血再灌注后大脑海马区自噬的研究

目的检测大鼠脑缺血再灌注后海马神经细胞损伤及自噬变化,并比较海马CA_1及CA_3区的自噬情况。方法用线栓法制作大鼠脑局部缺血再灌注模型,实验动物随机分为:对照组(Control组)、假手术组(Sham组)和大脑中动脉栓塞再灌注组(MCAO组)。HE染色检测大鼠海马神经细胞损伤。透射电镜下观察海马神经元内自噬小体。免疫荧光法检测自噬相关蛋白LC3、Beclin-1的表达水平。结果与Control组及Sham组比较,大鼠脑缺血再灌注后,海马神经细胞损伤严重;海马神经元内有自噬体形成;自噬标记物LC3、Beclin-1蛋白表达水平显著增加,且CA_1区的表达量明显高于CA_3区(差异均具有统计学意义P0.05)。结论脑缺血再灌注可激活海马神经细胞内的自噬,并进一步引起细胞损伤;模型动物海马CA_1区的自噬水平显著高于CA_3区,暗示CA_1区对脑缺血损伤具有较高的敏感度。     

神经节苷脂对不完全性脑缺血后海马CA1区NOS阳性神经元表达的影响

目的:探讨神经节苷脂(GM1)对不完全性脑缺血及再灌注不同时间后海马CA1区一氧化氮合酶(NOS)的影响及对神经元的保护作用.方法:用双侧颈总动脉夹闭加放血的方法制成大鼠不完性脑缺血及再灌注模型,以还原尼克酰胺腺嘌呤二核苷酸脱氢酶(NADPH-d)组织化学方法观察缺血及再灌注后海马CA1区NOS阳性神经细胞变化及GM1对其影响.结果:海马CA1区神经细胞受损,在缺血30 min时NOS阳性细胞数最高(44.5±7.4),为对照组的2倍,再灌注2 h,12 h,24 h,3 d后逐渐下降,5 d时恢复正常水平.而GM1能防止脑缺血及再灌注后神经细胞受损和NOS阳性神经细胞变化.结论:GM1对大鼠不完全性脑缺血及再灌注不同时间后海马CA1区NOS的表达有抑制作用,并对神经元具有保护作用.     

γ-氨基丁酸在大鼠急性脑缺血再灌注损伤中的作用

为了探讨GABA在大鼠急性脑缺血再灌注损伤中的作用,本实验采用Pulsinelli的4VO法制备了大鼠脑缺血灌注模型,利用高效液相色谱法观察脑缺血再灌注大后大鼠海马区GABA.GLU含量变化。发现缺血后GABA.GLU含量增高,再灌注后GABA含量明显下降。提示:再灌注后GABA含量减少,海马内源性抑制降低可能是脑缺血再灌注后神经元损伤加重的原因之一。     

MAP2在沙土鼠短暂性前脑缺血损伤中表达的变化

目的：研究短暂性脑缺血再灌注损伤时微管相关蛋白（MAP2）表达的动态变化及意义。方法：采用沙土鼠一过性前脑缺血再灌模型，以免疫组织化学染色法，观察缺血5min再灌注0h,3h,24h,48h,72h,7d海马区MAP2表达的动态变化以及观察相应时间点海马区神经元病理组织学变化。结果：在正常的沙土鼠脑内，神经元呈MAP2染色阳性反应，在缺血5min再灌注后，海马区出现了MAP2染色减弱或消失区，随再灌注时间的延长，染色减弱或消失区扩大，但主要限经马区，相应神经元的病理组织学变化也随再灌注时间的延长而加重。结论：MAP2免疫组织化学法可显示神经元形态及脑缺血超早期病变；短暂性脑缺血再灌注损伤在脑内并不是均一地发生，而是存在着选择性易损伤区，海马CA1区发生了广泛的迟发性神经元死亡，MAP2的分解破坏或合成障碍，可能参与了脑缺血再灌注的损伤机制。     

神经节苷脂对不完全性脑缺血后海马CA1区NOS阳性神经元表达的影响

目的 :探讨神经节苷脂 (GM1)对不完全性脑缺血及再灌注不同时间后海马CA1区一氧化氮合酶 (NOS)的影响及对神经元的保护作用。方法 :用双侧颈总动脉夹闭加放血的方法制成大鼠不完性脑缺血及再灌注模型 ,以还原尼克酰胺腺嘌呤二核苷酸脱氢酶 (NADPH d)组织化学方法观察缺血及再灌注后海马CA1区NOS阳性神经细胞变化及GM1对其影响。结果 :海马CA1区神经细胞受损 ,在缺血 30min时NOS阳性细胞数最高 (44 .5±7.4 ) ,为对照组的 2倍 ,再灌注 2h ,12h ,2 4h ,3d后逐渐下降 ,5d时恢复正常水平。而GM1能防止脑缺血及再灌注后神经细胞受损和NOS阳性神经细胞变化。 结论 :GM1对大鼠不完全性脑缺血及再灌注不同时间后海马CA1区NOS的表达有抑制作用 ,并对神经元具有保护作用。     

阻断缝隙连接对局灶性脑缺血再灌注后海马迟发性神经元死亡及Bax表达的影响

目的 探讨阻断缝隙连接对大鼠局灶性脑缺血再灌注后海马迟发性神经无死亡(delayed neu-ronal death,DND)及Bax表达的影响.方法 术前2 h左侧脑室注射缝隙连接阻断剂甘珀酸(carbenoxolone,CBX),颈内动脉插线法制备大鼠大脑中动脉缺血模型,采用TUNEL及免疫荧光技术,观察3 d后海马DND及Bax表达水平的变化.结果 缺血再灌注生理盐水有45%的大鼠出现海马DND;用CBX后仅30%的大鼠出现海马DND,机率明显减小(P<0.01);与假手术组比较,缺血再灌注中CBX组Bax的表达水平明显增高,但低于缺血再灌注生理盐水(P<0.01).结论 缝隙连接与局灶性脑缺血再灌注引起的海马DND有密切关系,其原因可能与缺血再灌注后凋亡启动信号由缺血再灌注区通过缝隙连接向远隔部位播散有关.Bax参与了海马神经元凋亡的调节.     

脑缺血预处理对缺血再灌注损伤的保护作用

目的　观察缺血预处理对脑缺血再灌注损伤的保护作用。方法　采用四血管阻断法对实验鼠分组进行全脑缺血预处理及缺血后再灌注, 半定量法观察海马区神经元受损情况。结果　实验组四血管阻断３ 分钟（ 预处理） 后海马区神经元受损与对照组无显著差异;３ 天间隔６ 分钟全脑缺血再灌注组神经元受损较其他组明显减轻。结论　缺血预处理对脑缺血再灌注损伤保护作用与全脑缺血预处理时间, 后续全脑缺血再灌注损伤时间及两者间的时间间隔有关。     

大鼠全脑缺血再灌注损伤后海马CA1区神经元酪氨酸羟化酶和多巴胺-β-羟化酶表达的变化

目的　研究大鼠全脑缺血再灌注损伤后酪氨酸羟化酶 (TH)和多巴胺 β 羟化酶 (DβH)表达的改变及意义。方法　利用改良四血管闭塞法 ,建立大鼠全脑缺血模型。于缺血再灌注后 1,3,5d断头取脑 ,行免疫组化染色 ,在光镜下观察海马CA1区神经元TH及DβH表达的变化 ,并计数海马CA1区正常神经元。结果　全脑缺血再灌注后 1d ,TH及DβH的表达呈阴性 ,海马CA1区神经元未见显著的病理形态学改变 ;全脑缺血再灌注后 3d ,TH及DβH呈阳性表达 ,海马CA1区可见部分神经元死亡 ;全脑缺血再灌注后 5d ,TH及DβH呈明显阳性表达 ,海马CA1区可见大部分神经元死亡。结论　全脑缺血再灌注后 ,由于TH及DβH异常表达 ,使得儿茶酚胺生物合成增加 ,这可能是短暂性脑缺血损伤的机理之一。     

脑缺血再灌注损伤过程中脑的病理变化与脑内脑源性神经营养因子的基因表达

目的 研究在脑缺血-再灌注损伤过程中，脑组织的病理变化与脑源性神经营养因子(brain derived neurotrophic factor，BDNF)基因表达之间的关系。方法 采用Zea longa线栓法创建局部脑缺血-再灌注模型。光镜下观察病理变化，原位寡核酸分子杂交检测在脑缺血-再灌注损伤过程中，脑的不同区域BDNF mRNA的表达，图像分析BDNF的间接定量水平。结果 (1)脑缺血和脑缺血再灌注均可导致BDNF mRNA在脑的广泛区域表达活跃；(2)损伤过重反而抑制BDNF mRNA的表达；(3)BDNF mRNA的表达具有组织差异性；(4)脑缺血-再灌注后，早期BDNF mRNA的表达水平即明显增加，12h达高峰。结论 BDNF的提高是一种保护性反应，脑缺血和脑缺血再灌注损伤均可以导致BDNF mRNA在脑的广泛区域表达水平明显提高，表达水平与局部神经元的抗损伤能力呈正相关，与病理改变呈负相关。     

Expression of brain-derived neurotrophic factor in rat hippocampus following focal cerebral ischemic injury

BACKGROUND： The functional role of brain-derived neurotrophic factor （BDNF） is enhanced following cerebral ischemic injury providing neurons with an important self-protection mechanism in early stage ischemia/hypoxia. OBJECTIVE： To investigate the expression pattern of BDNF in different rat hippocampal regions following focal cerebral ischemic injury. DESIGN, TIME AND SETTING： We performed a comparative and neurobiological study of animals in the Department of Histology and Embryology and the Central Laboratory, Hebei Medical University from March to December 2003. MATERIALS： Forty healthy Sprague Dawley rats were randomly divided into a cerebral ischemia group and a sham operation group, with 20 rats per group. METHODS： In the cerebral ischemia group, we occluded the right middle cerebral artery with a suture, threading it to a depth of 17-19 mm. In the sham operation group, the threading depth was approximately 10mm. MAIN OUTCOME MEASURES： We analyzed the expression of BDNF in different hippocampal regions by immunohistochemical staining of brain sections taken on post-operative days 7, 14, 21 and 30. RESULTS： Sham operation group： We observed a number of a few BDNF-positive cells with light staining in the hippocampal CA1 CA4 regions and dentate gyms. Cerebral ischemia group： compared with the sham operation group, BDNF increased on day 7, significantly increased on day 14, and reached a peak on day 21 （P 〈 0.05）. Furthermore, irnmunologically reactive products were darkly stained, and neurons had long axons. BDNF was particularly highly expressed in the hippocampal CA3 and CA4 regions and dentate gyms. CONCLUSION： Cerebral ischemic injury can damage hippocampal neurons. Neurons can increase their anti-ischemic capacity by increasing BDNF expression in the hippocampal CA3 and CA4 regions and dentate gyms.     

亚低温对大鼠全脑缺血再灌注损伤后海马CA1区c-Jun蛋白表达的影响

目的研究亚低温对大鼠全脑缺血再灌注损伤后海马CA1区神经元的保护作用,并探讨其可能的机制。方法采用四血管阻断法建立大鼠全脑缺血模型。SD大鼠,随机分为假手术组(SH组)、常温组(IR组)和亚低温组(HIR组)。各组在全脑缺血15min后分别再灌注6h、12h、1d、3d,采用苏木素-伊红(HE)染色观察各时间点海马CA1区细胞形态学变化和TUNEL法检测海马CA1区神经元凋亡,免疫印迹检测c-Jun蛋白表达。结果(1)HE染色结果 IR组和HIR组于全脑缺血再灌注后6h,HE染色未见明显改变,IR组缺血再灌注1d时CA1区出现严重改变,3d时损伤最严重,出现细胞数目减少,细胞胞体缩小、胞核固缩深染,损伤严重,排列紊乱,核膜不清,核仁消失。而HIR组海马存活的锥体细胞数较之IR组12h、1d、3d时间点均明显增加(P<0.05)。(2)TUNEL标记IR组于缺血再灌注后6h在海马CA1区阳性细胞开始增多,缺血再灌注1 d时阳性细胞数最多。而HIR组各时间点阳性细胞数均较IR组明显减少(P<0.01)。(3)免疫印迹结果全脑缺血再灌注后6h c-Jun蛋白在IR组海马CA1区表达开始增加,12h达高峰,持续到3d;HIR组在各时间点的表达均弱于IR组(P<0.01)。结论亚低温通过减少海马CA1区c-Jun的表达,抑制海马CA1区神经元的凋亡,可能是亚低温脑保护作用的机制之一。     

大鼠脑缺血再灌注后星形胶质细胞反应性变化差异与海马CA1区的迟发性神经元死亡

BACKGROUND： Blood supply to the hippocampus is not provided by the middle cerebral artery. However, previous studies have shown that delayed neuronal death in the hippocampus may occur following focal cerebral ischemia induced by middle cerebral artery occlusion.
OBJECTIVE： To observe the relationship between reactive changes in hippocampal astrocytes and delayed neuronal death in the hippocampal CA1 region following middle cerebral artery occlusion.
DESIGN, TIME AND SETTING： The immunohistochemical, randomized, controlled animal study was performed at the Laboratory of Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, from July to November 2007.
MATERIALS： Rabbit anti-glial fibrillary acidic protein （GFAP） （Neomarkers, USA）, goat anti-rabbit IgG （Sigma, USA） and ApoAlert apoptosis detection kit （Biosciences Clontech, USA） were used in this study. METHODS： A total of 42 healthy adult male Wistar rats, aged 3–5 months, were randomly divided into a sham operation group （n = 6） and a cerebral ischemia/reperfusion group （n = 36）. In the cerebral ischemia/reperfusion group, cerebral ischemia/reperfusion models were created by middle cerebral artery occlusion. In the sham operation group, the thread was only inserted into the initial region of the internal carotid artery, and middle cerebral artery occlusion was not induced. Rats in the cerebral ischemia/reperfusion group were assigned to a delayed neuronal death （＋） subgroup and a delayed neuronal death （–） subgroup, according to the occurrence of delayed neuronal death in the ischemic side of the hippocampal CA1 region following cerebral ischemia.
MAIN OUTCOME MEASURES： Delayed neuronal death in the hippocampal CA1 region was measured by Nissl staining. GFAP expression and delayed neuronal death changes were measured in the rat hippocampal CA1 region at the ischemic hemisphere by double staining for GFAP and TUNEL.
RESULTS： After 3 days of ischemia/reperfusion, astrocytes with abnormal morphology were detected in the rat hippocampal CA1 region in the delayed neuronal death （＋） subgroup. No significant difference in GFAP expression was found in the rat hippocampal CA1 region at the ischemic hemisphere in the sham operation group, delayed neuronal death （＋） subgroup and delayed neuronal death （–） subgroup （P 〉 0.05）. After 7 days of ischemia/reperfusion, many GFAP-positive cells, which possessed a large cell body and an increased number of processes, were activated in the rat hippocampal CA1 region at the ischemic hemisphere. GFAP expression in the hippocampal CA1 region was greater in the delayed neuronal death （＋） subgroup and delayed neuronal death （–） subgroup compared with the sham operation group （P 〈 0.01）. Moreover, GFAP expression was significantly greater in the delayed neuronal death （–） subgroup than in the delayed neuronal death （＋） subgroup （P 〈 0.01）. After 30 days of ischemia/reperfusion, GFAP-positive cells were present in scar-like structures in the rat hippocampal CA1 region at the ischemic hemisphere. GFAP expression was significantly greater in the delayed neuronal death （＋） subgroup and delayed neuronal death （–） subgroup compared with the sham operation group （P 〈 0.05）. GFAP expression was significantly lower in the delayed neuronal death （–） subgroup than in the delayed neuronal death （＋） subgroup （P 〈 0.05）. The delayed neuronal death rates were 42% （5/12）, 33% （4/12） and 33% （4/12） at 3, 7 and 30 days, respectively, followingischemia/reperfusion. No significant differences were detected at various time points （χ2 = 0.341, P 〉 0.05）.
CONCLUSION： The activation of astrocytes was poor in the hippocampal CA1 region during the early stages of ischemia, which is an important reason for delayed neuronal death. Glial scar formation aggravated delayed neuronal death during the advanced ischemic stage.     

CoQ10 fails to protect brain against focal and global ischemia in rats

OBJECTIVE: Release of oxygen free radicals occurs following cerebral ischemia. Studies show that oxygen free radicals mediate ischemic brain injury. CoQ10 is a potent free radical scavenger and may offset brain injury associated with reperfusion. We tested exogeneous CoQ10 as a neuroprotectant in rats following both global and focal ischemic insults. METHODS: Rats were subjected to either 4-vessel occlusion ischemia (4-VO, 10 min occlusion, 7-day survival) or middle cerebral artery occlusion (MCAO, 120 min-occlusion, 22.5 h survival). Regional cerebral blood flows (rCBF) and physiological variables such as blood pressure, pO2, pCO2, plasma glucose and hematocrit were monitored and measured in focal ischemia. The animals were randomized to receive treatments of either phosphate buffered saline (PBS) vehicle or CoQ10 following global or focal ischemia. Injection times were at the end of ischemia and 3 h later for both models of ischemia. Histological outcomes are expressed as a percentage of hippocampal CA(1) cell injury in global ischemia or percentage of cortical infarct over that of non-ischemic hemisphere in focal ischemia. RESULTS: In global ischemia, animals treated with PBS vehicle and CoQ10 had 86+/-5% (n=8) and 83+/-10% (n=8), respectively, of hippocampal CA(1) cell injury (P>0.05). The percentage of infarct volumes in animals following focal ischemia were 23+/-9% (control, n=10) and 25+/-9% (CoQ10, n=10). There were no temperature or physiological differences between the two treatment groups. CONCLUSION: Acute treatment with CoQ10 via intraperitoneal injection does not prevent neuronal injuries following global and focal ischemia.     

亚低温对局灶性脑缺血再灌注大鼠脑皮质神经元凋亡及存活素、脑源性神经营养因子表达的影响

目的观察亚低温干预对局灶性脑缺血再灌注大鼠脑皮质神经元凋亡及存活累(Survivin)、脑源性神经营养因子(BDNF)表达的影响,探讨Survivin、BDNF在亚低温脑保护机制中的作用。方法采用线栓法制备成年雄性SD大鼠大脑中动脉闭塞(MCAO)局灶性脑缺血再灌注改良模型,将90只大鼠随机分为假手术组、常温缺血组和亚低温缺血组,缺血组分别于缺血3h再灌注3h、6h、12h、24h、48h、72h、7d处死,亚低温缺血组于缺血后10min实施全身亚低温持续3h。进行TUNEL染色及免疫组化染色,检测梗死灶周围皮质神经元凋亡数量和Sur-vivin、BDNF的表达水平。结果 (1)亚低温缺血组和常温缺血组于再灌注6h皮质区均出现TUNEL染色阳性细胞,72h达高峰,随后逐渐减少,两组内相邻时间点比较差异均有统计学意义(P<0.05);在相同时间点亚低温缺血组凋亡细胞数明显少于常温缺血组,两组间比较差异有统计学意义(P<0.05)。(2)亚低温缺血组于再灌注3hSurvivin、BDNF表达有所增加,BDNF于24h达高峰,Survivin于48h达高峰,随后表达逐渐降低,但7d时仍高于假手术组,常温缺血组表达趋势与之相似,两组各时间点Survivin、BDNF表达均高于假手术组,差异有统计学意义(P<0.05);除再灌注3h Survivin表达在亚低温缺血组与常温缺血组间无明显差异外,其余各时间点亚低温缺血组Sur-vivin、BDNF表达均高于常温缺血组,差异有统计学意义(P<0.05)。结论亚低温干预可抑制梗死灶周围脑皮质神经细胞凋亡,促进存活素及脑源性神经营养因子的表达,发挥脑保护作用。     

细胞外信号调节激酶在NGF/VEGF介导的神经保护作用中的动态变化及其调控机制

目的探讨细胞外信号调节激酶1(ERK1)在局灶性脑缺血/再灌注不同时间、不同脑区的动态时空变化,以及其在NGF/VEGF介导的神经保护作用中的调控表达机制。方法采用兔大脑中动脉阻断(MCAO)局灶性脑缺血再灌注模型,所有动物随机分为假手术组(n=6)、缺血/再灌注组(n=60)、因子干预组(n=40)。应用免疫组化检测ERK1在脑缺血/再灌注损伤不同脑区的动态表达,同时,应用免疫组化、流式细胞术和电镜检测caspase-3表达、凋亡和超微结构的变化。结果免疫组化分析显示,再灌注损伤1hERK1首先在海马CA3和齿状回(DG)表达增加,6h后其它脑区也相继增加,随再灌注时间延长而加剧,1~3d达高峰。再灌注1hcaspase-3活性表达在各脑区迅速增加,3d达高峰。应用神经保护剂(NGF/VEGF)后各脑区ERK1表达呈明显抑制,caspase-3表达同时被抑制。结论ERK信号通路可能通过调节死亡受体途径介导神经保护作用,抑制ERK信号途径可能是减轻脑缺血损伤过程中神经细胞死亡的有效方法。     

大鼠脑缺血再灌流后海马氨基酸水平变化与神经元损害的关系探讨

目的探讨脑缺血再灌流后海马氨基酸递质变化与神经元损害的关系。方法建立大鼠前脑缺血再灌流模型,测定海马ＣＡ１区和ＣＡ３／齿状回区游离氨基酸含量,观察阻断隔－海马通路对海马神经元损害和氨基酸水平的影响。结果（１）海马结构中仅ＣＡ１区神经元明显损害,但ＣＡ１区和ＣＡ３／齿状回区的Ｇｌｕ、Ａｓｐ和ＧＡＢＡ含量无差异。（２）阻断隔－海马通路可明显减轻海马神经元损害,但对海马氨基酸水平变化无影响。结论脑缺血再灌流后,氨基酸递质水平的异常变化不是海马ＣＡ１区神经元选择性易损的唯一决定因素,隔－海马通路末梢释放的神经递质也参与海马神经元损害过程。