亚低温对脑缺血区P53蛋白表达的影响

目的　在尿激酶溶解大鼠脑血栓治疗中,研究亚低温对溶栓复流后大脑中动脉缺血区 Ｐ５３蛋白表达的影响。方法　应用肾血管性高血压大鼠（ Ｒ Ｈ Ｒ Ｓ Ｐ）,用光化学法制成一侧大脑中动脉闭塞（ Ｍ Ｃ Ａ Ｏ）模型,在血栓形成后 ０．５ｈ 应用尿激酶静脉溶栓复流后,用免疫组织化学的方法研究 Ｐ５３蛋白的表达。结果　亚低温组 Ｐ５３蛋白的表达,明显弱于正常体温组。结论　亚低温降低脑缺血区域的 Ｐ５３蛋白的表达,可能是亚低温产生脑保护的机制之一。     

大鼠蛛网膜下腔出血后脑组织P53基因表达与细胞损伤

目的　探索防治蛛网膜下腔出血（ Ｓ Ａ Ｈ）引起的脑血管痉挛（ Ｃ Ｖ Ｓ）的新途径。方法　利用大鼠 Ｓ Ａ Ｈ 模型，设立对照组、 Ｓ Ａ Ｈ 组、放线菌素酮治疗组（ Ｃ Ｈ Ｘ 组）。经 Ｄ Ｉ Ｇ Ｒ Ｔ Ｐ Ｃ Ｒ 对不同时间大鼠脑组织 Ｐ５３基因进行检测。结果　对照组、 Ｃ Ｈ Ｘ 组 Ｐ５３基因表达相近， Ｓ Ａ Ｈ 组 Ｐ５３基因表达增高。显微镜下见 Ｃ Ｈ Ｘ 组病理形态学变化近似正常， Ｓ Ａ Ｈ 组神经细胞损伤严重。结论　大鼠 Ｓ Ａ Ｈ 后 Ｃ Ｖ Ｓ所致的脑缺血，脑组织 Ｐ５３基因表达明显增高。大鼠 Ｓ Ａ Ｈ 模型 Ｐ５３基因表达与脑神经元细胞损伤明显相关。放线菌素酮通过抑制 Ｐ５３基因表达从而抑制其诱导的损伤。     

脑缺血再灌流大鼠脑胶质源性神经营养因子基因表达的变化

探讨脑缺血再灌流不同时程及不同程度缺血对海马及皮层胶质源性神经营养因子（ｇｌｉａｌｃｅｌｌｌｉｎｅ ｄｅｒｉｖｅｄ ｎｅｕｒｏｔｒｏｐｈｉｃ ｆａｃｔｏｒ, ＧＤＮＦ）基因表达的影响,以及Ｎ甲基Ｄ天冬氨酸（Ｎｍ ｅｔｈｙｌＤｓａｐａｒｔａｔｅ, ＮＭＤＡ）受体拮抗剂,钙离子通道阻断剂是否能调节缺血病态下ＧＤＮＦｍ ＲＮＡ的表达。参照Ｓｍ ｉｔｈ 等方法建立大鼠前脑缺血再灌流动物模型。用ＤＩＧＯｌｉｇｏｎｕｃｌｅｏｔｉｄｅ ３′ｅｎｄ ｌａｂｅｌｉｎｇ Ｋｉｔ,标记５１ ｍ ｅｒ的ＧＤＮＦ寡核苷酸探针在含有海马结构的冰冻组织切片上进行原位杂交检测ＧＤＮＦｍ ＲＮＡ的表达。１０ ｍ ｉｎ 缺血再灌流２ ｈ,齿状回ＧＤＮＦｍ ＲＮＡ表达上调。再灌流６ ｈ,ＣＡ１,ＣＡ３ 和皮层ＰＡＲ区ＧＤＮＦｍ ＲＮＡ表达亦见增多,２４ ｈ 达高峰。Ｋｅｔａｍ ｉｎｅ 可使ＧＤＮＦ的基因表达在海马结构及皮层ＰＡＲ区明显低于相应的缺血再灌流组,统计学差异显著（Ｐ＜ ００５）。脑缺血再灌流时ＧＤＮＦ基因表达增加,对缺血神经元可能起保护作用。Ｋｅｔａｍ ｉｎｅ可阻断缺血后ＧＤＮＦｍ ＲＮＡ 的表达增加,提示ＮＭＤＡ谷氨酸受体很可能参与介导了缺     

大鼠脑缺血再灌流后海马区一氧化氮合酶活性的变化

目的：观察鼠全脑缺血再灌流后海马区ＮＯＳ活性的变化。方法：采用大鼠４血管关闭方法制作全脑缺血再灌流模型。实验动物分为假手术组、缺血１０ｍｉｎ组、再灌注１、２、３ｄ组。测定脑缺血再灌流后海马区ＮＯＳ活性的变化。结果：全脑缺血曹澡注后海马组织ＮＯＳ活性被激活上调。结论：ＮＯ可能参与了海马ＣＡ１区迟发性神经元死亡（ＤＮＤ）的发生。     

自由基在大鼠全脑缺血再灌流损伤中作用机理及保精增智液的保护作用

本文采用大鼠４血管关闭方法制作了全脑血再灌流模型。于再灌流后２４ｈ取双侧海马，分别采用Ｐｒｏｇａｌｌｏｌ－ＮＢＴ和改良的ＴＢＡ法测定了ＳＯＤ活性和ＬＰＯ含量。结果ＳＯＤ明显低于对照组而ＬＰＯ明显高于对照组（Ｐ＜０．０１）。同时观察了一种新的中药方剂—保精增智液对自由基的拮抗作用，实验证明该药造模后给药效果不明显（Ｐ＞０．０５），造模前给药可使ＬＰＯ下降及ＳＯＤ上升，与对照组比较差异显著（Ｐ＜０．０１）。证明该药对全脑缺血再灌流损伤引起的自由基升高有保护作用。     

脑缺血选择性海马CA1区神经元损害的实验研究

采用Ｐｕｌｓｉｎｅｌｉ－Ｂｒｉｅｒｌｅｙ４血管阻塞脑缺血模型观察了大鼠全脑缺血２０ｍｉｎ再灌流８ｈ，ｃ－ｆｏｓ基因表达及再灌流７ｄ海马ＣＡ１区迟发性神经元损害。在缺血再灌流早期（８ｈ）海马ＣＡ１区极少ｃ－ｆｏｓ表达，而齿状回、海马ＣＡ３区、杏仁核大量ｃ－ｆｏｓ表达。缺血再灌流晚期（７ｄ）镀银染色显示海马ＣＡ１区神经元及其突触终末带呈黑色溃变相，而齿状回、海马ＣＡ３区、杏仁核呈金黄色正常相。相邻切片ＨＥ染色示缺血组海马ＣＡ１区核完整的锥体细胞数（５±２．６个／２００μｍ）与对照组（４０±２．９个／μｍ）比较差异有显著意义（Ｐ＜０．０１）。脑缺血诱导的ｃ－ｆｏｓ基因表达对于缺血易损海马ＣＡ１区迟发性神经元坏死可能起直接的调控作用。     

保精增智液对大鼠迟发性神经元坏死海马CA_1区光镜和电镜改变的影响

本研究采用Ｗｉｓｔａｒ大鼠４血管关闭法制成全脑缺血１０ｍｉｎ再灌流动物模型造成迟发性神经元坏死（ＤＮＤ），分别观察了海马ＣＡ１区再灌流后３ｄ和５ｄ的普通病理和超微结构改变，同时观察了中药保精增智液对ＤＮＤ的保护作用，结果显示再灌流３ｄ时电镜下ＣＡ１区神经元内亚细胞结构改变明显，５ｄ时光镜下出现明显的神经元脱失，造模前８ｄ给药组可明显改善再灌流３ｄ时的亚细胞结构的改变，使５ｄ时神经细胞存活数上升（１８１．６±１５．１个／ｍｍ，对照组４１．４±４．０，Ｐ＜０．０１）。该药对大鼠短暂全脑缺血再灌流造成的ＤＮＤ有保护作用。     

急性脑缺血再灌流后脑组织钙依赖性中性蛋白酶的变化

采用大鼠全脑缺血模型，观测脑缺血再灌流脑组织钙依赖性中性蛋白酶（ｃａｌｃｉｕｍ－ａｃｔｉｚａｔｅｄｍｅｕｔｕａｌｐｒｏｔｅｉｍａｓｅ，ｃａｌｐａｉｎ）活性的变化及海马ＣＡ１区神经元损害改变。结果显示脑缺血再灌流脑组织ｃａｌｐａｉｎⅠ和ｃａｌｐａｉｎⅡ活性都明显升高（Ｐ＜０．０１），ＣＡ１区神经元密度相应下降，提示ｃａｌｐａｉｎｓ在脑缺血损害过程中可能起一定作用。     

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     

巴曲酶对大鼠脑缺血再灌流损伤保护作用机理的研究

为探讨巴曲酶对大鼠短暂性脑缺血再灌流损伤引起的细胞凋亡有无抑制作用，参照Ｓｍｉｔｈ等（１９８４）方法，制备大鼠前脑短暂性缺血再灌流模型，采用ＴＵＮＥＬ（脱氧核苷酸转移酶末端介导的ｄＵＴＰ－生物素切口末端标记）法，观察了海马脑区细胞凋亡的特征变化—ＤＮＡ降解片段（凋亡小体）。发现脑缺血１０ｍｉｎ再灌流２４ｈ，海马ＣＡ１区即可见凋亡小体，于再灌流４８ｈ、９６ｈ凋亡小体明显增多。给予巴曲酶（１．６ＢＵ／ｋｇ．ｉｖ）后上述变化被明显逆转。本实验提示巴曲酶对脑缺血再灌流损伤所引起的细胞凋亡有抑制作用。     

Astrocyte targeted overexpression of Hsp72 or SOD2 reduces neuronal vulnerability to forebrain ischemia

Brief forebrain ischemia is a model of the delayed hippocampal neuronal loss seen in patients following cardiac arrest and resuscitation. Previous studies demonstrated that selective dysfunction of hippocampal CA1 subregion astrocytes occurs hours to days before delayed neuronal death. In this study we tested the strategy of directing protection to astrocytes to protect neighboring neurons from forebrain ischemia. Two well‐studied protective proteins, heat shock protein 72 (Hsp72) or superoxide dismutase 2 (SOD2), were genetically targeted for expression in astrocytes using the astrocyte‐specific human glial fibrillary acidic protein (GFAP) promoter. The expression constructs were injected stereotacticly immediately above the hippocampal CA1 region on one side of the rat brain two days prior to forebrain ischemia. Cell type specific expression was confirmed by double label immunohistochemistry. When the expression constructs were injected two days before transient forebrain ischemia, the loss of CA1 hippocampal neurons observed seven days later was significantly reduced on the injected side compared with controls. This neuroprotection was associated with significantly better preservation of astrocyte glutamate transporter‐1 immunoreactivity at 5‐h reperfusion and reduced oxidative stress. Improving the resistance of astrocytes to ischemic stress by targeting either the cytosolic or mitochondrial compartment was thus associated with preservation of CA1 neurons following forebrain ischemia. Targeting astrocytes is a promising strategy for neuronal preservation following cardiac arrest and resuscitation. © 2010 Wiley‐Liss, Inc.     

Enhanced expression of p53 in reactive astrocytes following transient focal ischemia

The present study used immunohistochemistry to investigate p53 expression in rat brain following transient occlusion of the middle cerebral artery. In the control group, no p53-immunoreactive cells were found in any region of the central nervous system. P53 expression in reactive astrocytes was not obvious in the forebrain one day or three days following ischemic insults. Seven days following ischemic injury, increased expression of p53 was clearly detectable in reactive astrocytes in affected cortical regions, such as forelimb area, hindlimb area, and parietal cortex. At seven days of recirculation, there was also a significant increase in the number of p53-immunoreactive neurons in the cerebral cortex, striatum, and hippocampal CA1-3 regions. Although the present study has not addressed multiple mechanisms contributing to cell death following ischemic injury, the first demonstration of a significant increase in p53 expression in glial cells may prove useful for future investigations of the pathophysiology of ischemia.     

预缺血诱导大鼠CA1神经元中蛋白伴侣hsp70的表达并抑制蛋白聚集物的形成

目的 研究预缺血对蛋白伴侣hsp70表达和蛋白聚集物形成的影响,探讨其可能的脑保护机制.方法 采用大鼠双侧颈总动脉暂时夹闭法建立全脑缺血模型.大鼠分为3min缺血组,10min缺血组以及预缺血组.苏木素-伊红染色,光镜下随机计数分析预缺血后海马CA1区死亡神经元数量变化.免疫组织化学及激光扫描共聚焦显微镜法观察蛋白伴侣hsp70在CAI区神经元内的分布.差速离心分离细胞浆、细胞核及蛋白聚集物.蛋白印迹法检测不同缺血状态下海马CA1神经元内蛋白聚集物含量的变化,以及胞浆、胞核及蛋白聚集物内蛋白伴侣hsp70含量的变化.结果 组织学检查显示预缺血能够显著减少海马CA1区神经元死亡数量.预缺血诱导海马CA1区神经元内蛋白伴侣hsp70在再灌注后24h表达.预缺血处理后,海马CA1区神经元内蛋白聚集物显著减少.预缺血诱导的蛋白伴侣hsp70与再缺血形成的异常蛋白结合在一起并防止其聚集.结论 预缺血可能通过诱导蛋白伴侣hsp70的表达和抑制再缺血后蛋白聚集物的形成,减少再缺血引起的神经元死亡.     

Activation of mitogen-activated protein kinases after transient forebrain ischemia in gerbil hippocampus.

We investigated the expression, activation, and distribution of c-Jun N-terminal kinases (JNKs), p38 mitogen-activated protein kinases (p38s) and extracellular signal-regulated kinases (ERKs) using Western blotting and immunohistochemistry in gerbil hippocampus after transient forebrain ischemia to clarify the role of these kinases in delayed neuronal death (DND) in the CA1 subfield. Immunoblot analysis demonstrated that activities of JNK, p38, and ERK in whole hippocampus were increased after 5 min of global ischemia. We used an immunohistochemical study to elucidate the temporal and spatial expression of these kinases after transient global ischemia. The immunohistochemical study showed that active JNK and p38 immunoreactivities were enhanced at 15 min of reperfusion and then gradually reduced and disappeared in the hippocampal CA1 region. On the other hand, in CA3 neurons, active JNK and p38 immunoreactivities were enhanced at 15 min of reperfusion and peaked at 6 hr of reperfusion and then gradually reduced but was continuously detected 72 hr after ischemia. Active ERK immunoreactivity was observed transiently in CA3 fibers and dentate gyrus. Pretreatment with SB203580, a p38 inhibitor, but not with PD98059, an ERK kinase 1/2 inhibitor, reduced ischemic cell death in the CA1 region after transient global ischemia by inhibiting the activity of p38. These findings indicate that the p38 pathway may play an important role in DND during brain ischemia in gerbil. Components of the pathway are important target molecules for clarifying the mechanism of neuronal death.     

大鼠脑缺血后海马CA1区胶质纤维酸性蛋白表达与迟发性神经元死亡的关系

目的观察大鼠大脑缺血再灌注后海马CA1区胶质纤维酸性蛋白(GFAP)的表达与迟发性神经元死亡的关系。方法采用大鼠大脑中动脉阻塞再灌注模型(MCAO),将大鼠随机分为MCAO后3d、7d、30d组及假手术组,应用免疫荧光与TUNEL染色法分别观察脑缺血再灌注后不同时间点缺血侧海马CA1区GFAP表达情况和迟发性神经元死亡(DND)的变化。结果(1)3d组海马DND阳性(DND 组)的MCAO大鼠、海马DND阴性(DND-组)的MCAO大鼠与假手术组大鼠比较,缺血侧海马CA1区GFAP染色的平均光密度无显著性差异(P>0.05),但GFAP阳性细胞的形态发生变化;(2)7d组大鼠缺血侧海马CA1区GFAP阳性细胞大量活化增殖,表现为胞体变大,突起增多;DND( )、DND(-)组海马CA1区GFAP染色的平均光密度较假手术组增高(P<0.01),且DND(-)组的GFAP平均光密度较DND( )组明显增高(P<0.01);(3)30d组大鼠缺血侧海马CA1区GFAP表达呈瘢痕样改变,DND( )、DND(-)组与假手术组比较其GFAP染色的平均光密度明显增高(P<0.05),且DND( )组的GFAP平均光密度较DND(-)组明显增高(P<0.05)。结论大鼠MCAO后星形胶质细胞反应性变化的差异可能与海马CA1区迟发性神经元死亡的发生有关。     

Morphological investigation of the neuroprotective effects of graded hypothermia after diverse periods of global cerebral ischemia in gerbils

Hypothermia is known to be the most effective method to protect the neuronal damage induced by ischemia. In the present study, we investigated the histopathological consequences of hippocampal CA1 pyramidal neurons as well as the glial reactions in the hippocampus, after diverse periods of ischemic insult at graded intra-ischemic hypothermia ranging from 32 to 20°C. Gerbils were exposed to forebrain ischemia by clamping the bilateral common carotid arteries for 5–120 min depending upon the temperatures. The morphological study was performed 7 days after ischemia or sham-operation. Histopathological evaluation of delayed neuronal death (DND) was performed by Cresyl violet (CV) staining and MAP2 immunoreactivity. Glial reactions were examined by GFAP immunostaining and isolectin B4 histochemistry, corresponding to astrocytes and microglia, respectively. The forebrain ischemia at 32°C for 10 min and at 28°C for 20 min did not induce DND in the CA1 region. However, the ischemia at 32°C for 20 min and at 28°C for 30 min caused extensive degeneration of CA1 pyramidal neurons as observed in normothermic ischemic animals. Under the condition of deep hypothermia, the ischemia for 60 min at 24°C and for 120 min at 20°C which were the longest durations of each temperature within the limitation of the animal survival following 7 days, induced no DND in CA1 pyramidal neurons. The reactive changes of astrocytes were observed not only in ischemic animals with DND, but also in ischemic animals without DND. Computer image analysis showed that the area fraction of GFAP-positive structures in the CA1 region was significantly increased in both ischemic cases with and without DND compared with each sham group. In contrast, the distribution of activated microglia was much more restricted to the CA1 region and they were always accompanied by DND at 7 days postischemia. The present results demonstrate the remarkable neuroprotective effect of deep hypothermia that has been widely used in cardiovascular surgeries as the cerebroprotective strategy during total circulatory cessation. The findings also suggest that even under the condition of hypothermia, glial reactions may play an important role in neuronal survival and death after ischemia.     

大鼠局灶性脑缺血后CPP32和P53蛋白的表达

目的　探讨大鼠脑缺血后神经元损害过程中CPP32和P5 3蛋白表达的变化。方法　建立大鼠大脑中动脉闭塞 (MCAO 2h)模型 ,采用免疫组化方法观察CPP32和P5 3蛋白在大鼠脑缺血后不同时间的动态变化。结果　CPP32蛋白在脑缺血再灌注 2 2h和 4 6h ,阳性表达最明显。而P5 3在脑缺血再灌注 2 2h阳性表达最明显 ,并持续至再灌注 70h。阳性表达主要位于神经元严重受损的缺血区内。结论　CPP32和P5 3蛋白表达与脑缺血后神经细胞死亡关系密切。