谷氨酸对急性脑缺血再灌注大鼠皮层乙酰胆碱活性影响的在体 …

为了研究脑缺血时兴奋性氨基酸与胆碱能神经的关系，采用双侧颈总动脉夹闭（ＣＣＡＯ）的脑缺血动物模型，用乙酰胆碱离子选择性微电极（ＡＣｈ－ＩＳＭｓ）检测皮层ＡＣｈ释放量，观察脑缺血再灌注时谷氨酸对六鼠皮层ＡＣｈ释放量的影响。结果表明：１０＾－１ｍｏｌｏ／Ｌ Ｇｌｕ对ＡＣｈ－ＩＳＭｓ无干扰作用，在生理状态下不能显著地促进皮层ＡＣｈ的释放，但可使脑缺血３ｍｉｎ时皮层ＡＣｈ释放量较示加Ｇｌｕ组增加５８．１％     

脑缺血时大鼠大脑皮层乙酰胆碱含量变化的动态观察

本实验采用双侧颈总动脉夹闭（ＣＣＡＯ）和大脑中动脉闭塞（ＭＣＡＯ）两种脑缺血动物模型，分别用乙酰胆碱（ＡＣｈ）生物测定法检测皮层ＡＣｈ含量，ＡＣｈ离子选择性微电极（ＡＣｈ－ＩＳＭｓ）检测皮层ＡＣｈ释放量，乙酰胆碱酯酶（ＡＣｈＥ）生化测定法检测皮层ＡＣｈＥ活性，观察脑缺血时皮层ＡＣｈ含量的动态查化。结果发现：脑缺血可诱发皮层ＡＣｈ活度急剧上升，示ＡＣｈ突然大量释放，在ＣＣＡＯ组于缺血１０ｍｉｎ达到高峰（净增１．４４４ｍｍｏｌ／Ｌ），而ＭＣＡＯ组于缺血２ｍｉｎ即达高峰（净增１．５５３ｍｍｏｌ／Ｌ），随着缺血延长，二者均逐渐下降，于缺血３０ｍｉｎ时，虽较峰值要低，但明显高于缺血前水平，此时，ＡＣｈＥ活性巳明显低于缺血前，ＡＣｈ含量在ＣＣＡＯ组下降０．２５６μｇ／ｇ（Ｐ＞０．０５），在ＭＣＡＯ组则显著下降１．０１４μｇ／ｇ（Ｐ＜０．０１）。结果提示：皮层ＡＣｈ含量变化对缺血是敏感的；脑缺血时ＡＣｈ含量下降、释放增加、降解减弱，推测ＡＣｈ可能在缺血性脑损伤中起重要作用。     

脑缺血—再灌注损伤中兴奋性氨基酸的变化

目的：为观察了解谷氨酸（Ｇｌｕ）和γ－氨基丁酸（ＧＡＢＡ）在发生脑缺血－再灌注损伤时的变化规律。方法：采用Ｌｏｎｇａ＇ｓ方法建立鼠大脑中动脉脑缺血－再灌注模型，观察了正常对照组，单纯缺血２小时，单纯缺血３小时，缺血２小时－再灌注１小时，缺血３小时－再灌注１小时，Ｇｌｕ和ＧＡＢＡ的变化及二者之间的关系。结果：发生再灌注损伤时，Ｇｌｕ和ＧＡＢＡ的比例与正常对照组有显著差异（Ｐ＜０．０１）。结论：在缺血－再灌注损伤发生过程中，脑组织内不仅是Ｇｌｕ和ＧＡＢＡ含量发生变化，而且二者比例严重失调，以上两个方面在脑缺血－再灌注损伤中可能起一定作用。     

大鼠局灶性脑缺血再灌注后皮层ICAM-1表达增加

目的：研究大鼠局灶性脑缺血再灌注不同时相皮层 ＩＣＡＭ－１变化规律。方法：改良 Ｋｏｉｚｕｍｉ法建立 ＬＭＣＡＯ局灶性脑缺血再灌注模型;ＲＴ－ＰＣＲ和 Ｄｏｔ ｂｌｏｔｔｉｎｇ法分别检测 ＩＣＡＭ－１的转录和翻译水平变化。结果：缺血皮层 ＩＣＡＭ－１ｍＲＮＡ和 Ｉ－ＣＡＭ－１分别于缺血 ２ｈ和再灌注 ２ｈ显著升高,再灌注 １０和 ４６ｈ达高峰,持续 １周仍维持在较高水平。结论：ＩＣＡＭ－１在脑缺血再灌注时表达明显上调,介导白细胞和脑血管内皮细胞的粘附。ＩＣＡＭ－１ 将成为缺血性脑卒中治疗的新突破点。     

大鼠脑缺血再灌注区ICAM-1表达与白细胞浸润的观察及丹参的影响

目的　观察细胞间粘附分子（ Ｉ Ｃ Ａ Ｍ１） 蛋白在大鼠脑缺血再灌注的不同时程脑组织中的表达与中性白细胞浸润程度的关系及丹参对它们的影响。方法　 Ｓ Ｄ大鼠分为３ 组：假手术组、对照组及丹参组。大脑中动脉缺血２ ｈ 再灌注２ ｈ 、１２ ｈ、２４ ｈ 、４８ ｈ 、７２ ｈ 、７ ｄ、１４ ｄ 后,分别进行 Ｉ Ｃ Ａ Ｍ１ 免疫组织化学及组织 Ｈ Ｅ染色。结果　在脑缺血再灌早期,脑微血管内皮细胞 Ｉ Ｃ Ａ Ｍ１ 免疫反应开始逐渐增加,再灌注４８ ｈ 达到高峰,再灌注１４ ｄ 接近正常水平,同时脑缺血区中性白细胞浸润也随之增加,在时程上与 Ｉ Ｃ Ａ Ｍ１ 表达同步。丹参组,再灌注４８ ｈ 后, Ｉ Ｃ Ａ Ｍ１ 免疫阳性血管数及中性白细胞的浸润比同时间对照组明显降低。结论　脑缺血 Ｉ Ｃ Ａ Ｍ１ 的表达与中性白细胞浸润密切相关,丹参能降低 Ｉ Ｃ Ａ Ｍ１ 的表达,抑制中性白细胞的浸润。     

大鼠全脑缺血再灌流后4个脑区的谷氨酸,门冬氨酸,甘氨酸…

应用高效液相色谱仪，紫外分光光度检测器监测，测定大鼠全脑缺血再灌流后６ｈ￣７ｄ的海马、纹状体、丘脑和新皮层组织匀浆中谷氨酸（Ｇｌｕ）、门冬氨酸（Ａｓｐ）、甘氨酸（Ｇｌｙ）和ｒ－氨基丁酸（ＧＡＢＡ）含量变化。结果显示在海马和丘脑Ｇｌｕ含量于再灌流后６ｈ￣３ｄ下降（Ｐ〈０．０５和０．０１），ＧＡＢＡ含量升高（Ｐ〈０．０５和０．０１），在纹状体和新皮层除ＧＡＢＡ外，分别于６ｈ￣５ｄ均有不同呈度的升高。比     

羧乙基锗倍半氧化物对大鼠脑缺血再灌注损伤的保护作用

采用结扎双侧颈总动脉后再通的方法复制大鼠脑缺血再灌注损伤模型，通过测定再灌注后大鼠海马组织中脂质过氧化产物丙二醛（ＭＤＡ），超氧化物歧化酶（ＳＯＤ）与谷胱甘肽过氧化物酶（ＧＳＨ—Ｐｘ）及ＡＴＰａｓｅ的活性，观察了有机锗─羧乙基锗倍半氧化物（ＣＧＳ）对大鼠脑缺血再灌注后大鼠海马组织中ＭＤＡ水平，明显保护ＳＯＤ、ＧＳＨ─Ｐｘ、Ｎａ＋Ｋ＋─ＡＴＰａｓｅ及Ｃａ２＋─ＡＴ─Ｐａｓｅ活性。表明ＣＧＳ对大鼠脑缺血再灌注损伤具有保护作用。     

神经节苷脂GM1对大鼠MCAO／IR模型细胞外液氨基酸含量的影响——活…

目的 探讨ＧＭ１对脑缺血／再灌流的保护作用，动态观察神经节苷脂ＧＭ１对大鼠ＭＣＡＯ／ＩＲ模型细胞外液氨基酸类神经递质的影响。方法 采用缺血１ｈ再灌流２ｈ模型，用活体微透析法，检测缺血皮层脑组织外液内氨基酸类神经递质。结果（１）脑缺血后６０ｍｉｎ Ｇｌｕ上升到峰值浓度，随后很快下降，再灌流２ｈ内未见回升；（２）ＧＭ１组各类氨基酸都明显下降。结论 ＧＭ１能使包括Ｇｌｕ在内的多种氨基酸明显下降，它的保护     

实验性脑缺血在体及体外兴奋性氨基酸的改变及其意义

采用在体全脑缺血模型及体外海马脑片缺血孵育，观察脑缺血兴奋性氨基酸（Ｇｌｕ，ＡＳＰ）的改变，发现脑缺血及再灌注早期，体内海马组织兴奋性氨基酸（Ｇｌｕ，ＡＳＰ）显著降低，体外海马脑片孵育介质液中Ｇｌｕ，ＡＳＰ缺血时显著增高，提示脑缺血时兴奋性氨基酸过度释放参与缺血性脑损伤病理生理过程，并讨论兴奋性氨基酸改变的意义     

人工合成E-选择素治疗大鼠局灶脑缺血再灌注损伤的探讨

目的：探讨新的药物治疗脑缺血再灌注损伤。方法：用人工合成 Ｅ－选择素 ２ｍｇ·ｋｇ－１或 １０ ｍｇ·ｋｇ－１溶解于生理盐水中,静脉注入自发性高血压大鼠永久左侧大脑中动脉／颈总动脉（ＭＣＡ／ＣＣＡ）闭塞或ＭＣＡ／ＣＣＡ闭塞２ｈ后ＣＣＡ再灌注模型中。２４ｈ后,脑梗死体积用计算机扫描计算。结果：在永久性ＭＣＡ／ＣＣＡ闭死组中脑梗死体积没有差别,在ＭＣＡ／ＣＣＡ闭死后ＣＣＡ再灌注组中脑梗死体积有意义地缩小（Ｐ＜０．０１）。结论：Ｅ－选择素能够有效地减少大鼠脑缺血再灌注损伤。     

The disruption of spatial cognition and changes in brain amino acid, monoamine and acetylcholine in rats with transient cerebral ischemia

We investigated the disruption of spatial cognition due to transient forebrain ischemia using an 8-arm radial arm maze task in rats. Five or 10 min of ischemia did not affect the task acquisition. When rats established spatial cognition by daily training of the task, 10 min of ischemia significantly decreased the number of correct choices and increased the errors in the task when performed 24 h after reperfusion. These changes, however, returned to the normal level after about 4 days of daily training. Glutamic acid (Glu) and acetylcholine (ACh) release from the dorsal hippocampus (DH) was observed to transiently increase during ischemia. However, neither the content of noradrenaline (NA) nor the release of NA in the DH changed during ischemia. The NA and ACh release from the DH, however, gradually decreased during reperfusion, and the decrease became significant at 24 h after reperfusion. The NA content of the frontal cortex (FO and the DH increased 7 days after reperfusion. These results suggest that the disruption of spatial cognition induced by 10 min of ischemia may be attributed to a greater degree to the dysfunction of the hippocampal ACh and NA, and cortical NA systems, rather than to the development of neuronal cell death in these areas.     

Increased extracellular ascorbate release reflects glutamate re-uptake during the early stage of reperfusion after forebrain ischemia in rats

Ascorbate is highly concentrated in neuropils, and its extracellular release is closely related to that of the excitatory neurotransmitters. Thus, the extracellular release of ascorbate and glutamate was measured during the early stage of forebrain ischemia-reperfusion in the rat hippocampus using a microdialysis biosensor system. Male Wistar rats were anesthetized with halothane under mechanical ventilation and normothermia. Two probes of the microdialysis biosensor electrode were inserted in the hippocampus bilaterally. One probe was perfused with phosphate-buffered saline (PBS) and the oxidation signal of dialyzed ascorbate was recorded. A second electropolymerized probe was perfused with PBS containing glutamate oxidase for glutamate measurement. Forebrain ischemia-reperfusion was performed by bilateral carotid artery occlusion with hemorrhagic hypotension (MAP=30 mmHg) for 10 min (Group 10, n=10) or 15 min (Group 15, n=10), followed by reperfusion for 60 min. The release of glutamate increased significantly to 294% (Group 10) and 334% (Group 15) during ischemia, and then decreased rapidly. In Group 15, however, it remained significantly higher after reperfusion than in Group 10. The release of ascorbate increased significantly to 504% (Group 10) and 334% (Group 15) after reperfusion. In Group 10, it was significantly higher for 5-15 min after reperfusion than in Group 15. The marked increase of ascorbate during reperfusion was associated with the rapid decrease in glutamate. The extended time of ischemia significantly inhibited glutamate re-uptake and ascorbate release during reperfusion. These findings suggest the extracellular ascorbate release during reperfusion after global ischemia as a marker of glutamate re-uptake.     

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     

一氧化氮合酶、谷氨酸在局灶脑缺血中的变化

目的　观察一氧化氮合酶 (NOS)和谷氨酸 (Glu)在脑缺血时的改变。方法　应用大鼠大脑中动脉闭塞局灶脑缺血模型 ,观察脑缺血 1h后NOS和Glu含量的变化。结果　缺血 1h后NOS活性显著升高(P <0 .0 5 )、Glu含量亦显著升高 (P <0 .0 1) ;用L NMMA处理后 ,NOS活性显著降低 (P <0 .0 1) ,Glu含量亦降低 (P <0 .0 5 )。结论　Glu生成过多可激活NOS ;抑制NOS活性可减少Glu的生成。     

全脑缺血再灌注兴奋性氨基酸、线粒体钙、钙调素含量的变化

目的：采用大鼠全脑缺血再灌注模型,观察海马组织兴奋性氨基酸、线粒体钙、钙调素含量的变化,研究分析脑缺血再灌注损伤中兴奋性氨基酸与钙平衡紊乱的变化和作用。方法：测定假手术组,缺血３０ｍｉｎ再灌注６０ｍｉｎ和缺血３０ｍｉｎ再灌注１２ｈ组,脑海马组织兴奋性氨基酸、线粒体钙、钙调素的含量。结果：缺血３０ｍｉｎ再灌注６０ｍｉｎ海马组织兴奋性氨基酸明显低于假手术组（Ｐ＜０．０１）,线粒体钙、钙调素含量显著性高于假手术组（Ｐ＜０．０１）,缺血３０ｍｉｎ再灌注１２ｈ组同假手术组比较没有显著性差异（Ｐ＞０．０５）。结论：我们从鼠脑缺血再灌注时线粒体钙、钙调素含量升高证实钙平衡紊乱参于兴奋性氨基酸的缺血再灌注脑损伤过程     

大鼠局灶性脑缺血/再灌注后氧化性损伤标记8-ohdG及其修复酶rOGG1表达的研究

目的:检测大鼠脑缺血/再灌注后8-ohdG及rOGG1的表达,以了解神经元损伤是否与修复酶活性下降有关。方法:健康雄性Wistar大鼠,体重250±30g,随机分为2组:①造模组;②假手术组。①组大鼠用线栓法成功制作可复流的MCAO模型,2小时后再灌注。在再灌注后6小时、24小时、48小时将大鼠断头取脑,保存于液氮。均匀切成2mm厚的脑片,取第三片提取DNA或RNA。DNA样品经酶解后上高效液相-电化学检测器检测8-ohdG。RNA样品通过RT-PCR的方法探测rOGG1mRNA的表达。结果:①造模组脑缺血再灌注各时点8-ohdG的含量均较假手术组明显减少(P<0.01)。随再灌注时间的增加,脑缺血区rooG lmRNA的含量逐渐增加。②随再灌注时间的增加,造模组脑缺血区rooGlmRNA的表达量逐渐增加,但仍较假手术组明显减少(P<0.01)。结论:脑缺血区受损DNA修复不完全将导致DNA损伤积累从而引起神经元死亡。     

Two distinct components of initial glutamate release synchronized with anoxic depolarization in rat global brain ischemia

Numerous reports have suggested that anoxic depolarization is a critical event in the pathogenesis of cerebral ischemia. Extracellular glutamate concentration ([Glu]e) is closely related to the pathogenesis of ischemia. Therefore, these pathogenic mechanisms merit study, especially the relationship between [Glu]e elevation and the ionic basis of early changes in membrane potential after ischemic insult in vivo. It is often presumed from electrophysiological studies that a causal relationship exists between impaired glutamate uptake and/or progressive glutamate increase and anoxic depolarization, but few in vivo reports have found any sign of a progressive increase of [Glu]e elevation preceding anoxic depolarization. Recently, we reported the application of an oxygen-independent real-time technique for monitoring glutamate levels in the extracellular space during in vivo ischemia, and demonstrated that the massive glutamate release during ischemia is biphasic. In the present study, using this real-time monitoring system, we carried out a more detailed analysis of the initial events in the first phase of glutamate release during ischemia-induced anoxic depolarization. The shape of the rising slope that forms the peak of the first phase suggested two components. The second component was approximately 10 times steeper than the first, with two different components of the rise on the way to the peak of the biphasic [Glu]e elevation. This is the first report to demonstrate these components of the initial glutamate peak, and suggests a progressive second component of the [Glu]e increase preceding Ca2+-dependent release from synaptic vesicles with anoxic depolarization, in vivo.     

Lubeluzole inhibits accumulation of extracellular glutamate in the hippocampus during transient global cerebral ischemia

Increases in extracellular glutamate during cerebral ischemia may play an important role in neuronal injury. Lubeluzole is a novel neuroprotective drug, which in previous in vitro and focal ischemia studies has been shown to inhibit nitric oxide synthesis, to block voltage-gated Na+-ion channels, and to inhibit glutamate release. In this study, we investigated the ability of lubeluzole to inhibit glutamate accumulation during episodes of transient global cerebral ischemia. Twenty-five New Zealand white rabbits were randomized to one of four groups: a normothermic control group; a hypothermic group; a 1.25 mg/kg lubeluzole group; or a 2.5 mg/kg lubeluzole group. The animals were anesthetized, intubated, and ventilated before microdialysis probes were placed in the hippocampus. Lubeluzole was given intravenously 90 min before the onset of ischemia. Esophageal temperature was maintained at 38 degrees C in the control, and lubeluzole treated groups, while the animals in the hypothermia group were cooled to 30 degrees C. A 15-min period of global cerebral ischemia was produced by inflating a neck tourniquet. Glutamate concentrations in the microdialysate were determined using high-performance liquid chromatography (HPLC). During ischemia and early reperfusion, glutamate concentrations increased significantly in the control group and returned to baseline after 15 min of reperfusion. In the lubleuzole 2.5 mg/kg and hypothermia groups, glutamate levels were significantly lower (P<0.05) than in the control group and there was no significant change from baseline levels during the entire experiment. This study suggests that lubeluzole is effective in inhibiting extracellular glutamate accumulation during global cerebral ischemia, and has the potential to produce potent neuroprotection when instituted prior to an ischemic event.     

Trans-synaptic Modulation of Striatal ACh Release In Vivo by the Parafascicular Thalamic Nucleus

Electrical stimulation of the parafascicular but not the ventrolateral or dorsomedial thalamic nucleus (ten 0.5 ms, 10 V pulses, 140 pA) of freely moving rats induced a frequency-dependent (2.5, 5,10 and 20 Hz) increase in the extracellular acetylcholine (ACh) content of the dorsal striatum, assessed by trans-striatal microdialysis. The time-dependent effect of 10 Hz stimulation was studied. The peak increase, 39% above baseline, was attained during 4 min of stimulation. This was blocked by coperfusion with 5 pM tetrodotoxin, indicating that the release we measured represents a physiological process. The facilitatory effect of parafascicular nucleus stimulation does not appear to be associated with indirect action through the cerebral frontal cortex because acute lesion of the excitatory corticostriatal afferents, which by itself reduced basal ACh release by 40%, did not modify the effect of 10 Hz stimulation. The possible involvement of the fasciculus retroflexus in the facilitation of ACh release was also ruled out. The non-competitive NMDA-type receptor antagonist MK-801, applied by reversed dialysis (30 pM) or systemically injected (0.2 mg/kg), significantly reduced the basal ACh output and prevented the tetanus-evoked increase in ACh release. The results provide in vivo evidence that the activity of the cholinergic neurons in the dorsal striatum is trans-synaptically modulated by parafascicular nucleus excitatory afferents through activation of the NMDA subtype of glutamate receptors that is probably located in the striatum.