巴曲酶对脑缺血再灌注细胞外液单胺类及其代谢产物的影响——微透析研究

目的巴曲酶对脑缺血再灌流损伤的保护机理。方法采用脑内微透析技术结合高灵敏度的高压液相色谱－电化学检测手段（ＨＰＬＣ－ＥＤ），测定前脑缺血３０ｍｉｎ再灌注１２０ｍｉｎ时的纹状体细胞外液（ＥＣＦ）的ＤＡ、５－ＨＴ和ＮＥ及其代谢产物（５－ＨＩＡＡ）和ＨＶＡ的变化和巴曲酶的影响。结果显示脑缺血时，ＥＣＦＤＡ、ＮＥ及５－ＨＴ明显升高，巴曲酶能显著地降低脑缺血时ＥＣＦＤＡ及再灌注时ＥＣＦＨＶＡ和５－ＨＩＡＡ的水平。结论巴曲酶影响单胺神经递质是对脑缺血再灌注损伤起保护作用的机理之一     

巴曲酶对脑缺血再灌注细胞外液单胺类及其代谢产物的影响 …

目的 巴曲酶对脑缺血再灌流损伤的保护机理。方法 采用脑内微透析技术结合高灵敏度的高压液相色谱－电化学检测手段（ＨＰＬＣ－ＥＤ），测定前脑缺血３０ｍｉｎ再灌注１２０ｍｉｎ时的纹状体细胞外液（ＥＣＦ）的ＤＡ、５－ＨＴ和ＮＥ及其代谢产物（５－ＨＩＡＡ）和ＨＶＡ的变化和巴曲酶的影响。结果 显示脑缺血时，ＥＣＦ ＤＡ、ＮＥ及５－ＨＴ明显升高，巴曲酶能显著地降低脑缺血时ＥＣＦ ＤＡ及再灌注时ＥＣＦ ＨＶＡ和５     

内啡肽和单胺类介质在脑缺血时的动态变化

建立大白鼠全脑缺血动物模型，用ＲＩＡ法及荧光分光光度计检测了缺血脑组织匀浆的ＬＥＫ、β－ＥＰ．ＤｙｎＡ１－１３及 ５－ＨＴ和 ５－ＨＩＡＡ的含量，ＬＥＫ在脑组织缺血 ６０ ｍｉｎ时含量略下降，但无统计学意义；β－ＥＰ在脑组织缺血 ３０ ｍｉｎ时显著下降（Ｐ＜０． ０５），缺血 ６０ ｍｉｎ时下降非常显著（Ｐ＜０． ０１）；ＤｙｎＡ１－１３和 ５－ＨＩＡＡ含量在缺血 ６０ ｍｉｎ时明显上升，而 ５－ＨＴ含量则显著下降。上述结果提示内啡肽和单胺类介质均参与了缺血性脑损伤的病理过程。     

大鼠脑缺血时中枢单胺类神经递质的研究

大鼠脑缺血时中枢单胺类神经递质的研究周陆生，梁熙南，吴祥，魏琦近年来对脑血管病的神经生化研究发现，中枢单胺类神经递质的代谢异常对脑组织的损伤及发展有密切的影响，认为单胺类神经递质在缺血性脑损伤的病理生理过程中起重要作用。但由于各种原因，至今对它们代谢...     

脑损伤后脑细胞外液中糖代谢变化的微透析研究

目的探讨微透析技术监测脑损伤局部细胞外液(ECF)中糖代谢指标变化的意义。方法应用微透析技术动态收集大鼠轻、重度脑损伤局部的ECF透析液,观察其葡萄糖含量([Glu]d)和乳酸含量([Lac]d)的变化。结果透析管插入引起[Glu]d和[Lac]d的变化很小(P>0.05)。脑损伤后[Glu]d下降,与对照组及损伤前相比,相差显著(P<0.05),且损伤越重其变化越显著(P<0.05)。而脑损伤后[Lac]d则上升,与对照组及损伤前相比,相差显著(P<0.05),且损伤越重,其变化亦越显著(P<0.05)。脑损伤后[Glu]d和[Lac]d的变化分别与脑组织含水量呈显著负相关(P<0.05)和显著正相关性(P<0.05)。结论微透析技术是一种理想的动态监测脑损伤局部生化改变的方法;利用该技术监测损伤区ECF中糖代谢指标的异常变化,可以作为判定脑损伤程度的重要依据。     

脑缺血时皮层区细胞外液中氨基酸的动态变化——微透析观察

应用微透析技术,活体动态观察沙土鼠脑缺血时皮层区细胞外液(ECF)中氨基酸(AA)的变化。结果发现:(1)应用微透析技术在脑皮层中可检测到多种AA,其中包括神经介质类AA和非神经介质类AA;(2)脑缺血时,神经介质类AA显著升高,而非神经介质类AA仅轻度升高。结果提示,脑缺血时神经介质类AA和非神经介质类AA升高的机制可能不同,神经介质类AA在脑缺血损伤中起着重要作用。     

全脑缺血后海马区单胺类神经递质的变化

目的观察全脑缺血后大鼠海马区单胺类神经递质的变化规律,探讨其在缺血后迟发性神经元死亡中的作用。方法建立大鼠全脑缺血再灌注模型,观察全脑缺血再灌注后酪氨酸羟化酶(TH)、多巴胺-β-羟化酶(DβH)的表达并对海马区去甲肾上腺素(NE)、肾上腺素、多巴胺、5-羟色胺(5-HT)和单胺类神经递质代谢产物高香草酸(HVA)、5-羟吲哚乙酸(5-H IAA)的含量进行测定。结果对照组TH及DβH呈阴性表达。全脑缺血再灌注后1 d,3 d缺血组海马CA1区神经元TH及DβH表达阴性。5 d后神经元TH及DβH呈阳性表达;全脑缺血再灌注后6 h,缺血组海马区单胺类神经递质含量显著上升,NE、肾上腺素、多巴胺及5-HT分别为对照组的232.5%、347.3%、336.1%和210.1%,1 d后开始回落,3 d已明显低于对照组,5 d后又有回升并接近对照组;缺血组,海马区单胺类神经递质的代谢产物HVA、5-H IAA含量于全脑缺血再灌注后6 h开始上升,1 d依然保持较高的水平,至3 d回落,5 d接近对照组。结论全脑缺血再灌注后早期海马区单胺类神经递质含量显著上升;单胺类神经递质含量显著上升可能是导致迟发性神经元死亡的主要因素之一。     

STN—DBS对纹状体细胞外液牛磺酸含量的影响

目的探讨丘脑底核脑深部电刺激对猴帕金森病模型纹状体区细胞外液巾牛磺酸含量的影响。方法猴偏侧帕金森病模型,在患侧丘脑底核植入人用脑深部刺激电极,同期猴背部皮下植入脉冲发生器和皮下导线,通过测试后给予有效高频电刺激,利用微透析技术分别在打开脉冲发生器前和开机后的不同时间点在双侧壳核、尾状核头部细胞外液进行取样。对取样标本应用高效液相色谱荧光法检测其中牛磺酸的含量变化。结果电极侧壳核和尾状核的牛磺酸含量在开机后较开机前明显增加（P〈0．05）。结论丘脑底核脑深部刺激后可引起纹状体区细胞外液中牛磺酸的含量明显升高,这可能是丘脑底核脑深部电刺激的作用机制之一。     

脑缺血再灌注时鼠脑纹状体区细胞外液半胱氨酸含量变化及丹参的影响

目的动态观察脑缺血再灌注时鼠脑纹状体区细胞外液半胱氨酸（Ｃｙｓ）含量变化及丹参的影响，探讨Ｃｙｓ对缺血性神经元的损害作用。方法应用脑内微透析技术，采用高灵敏度的高压液相色谱－电化学检测手段，动态观察沙土鼠前脑缺血３０分钟再灌注１２０分钟时，纹状体区细胞外液Ｃｙｓ的变化。结果前脑缺血３０分钟时，细胞外液Ｃｙｓ浓度迅速升高，达缺血前的１８倍。再灌注３０、６０分钟时，分别为缺血前的５倍和２倍，９０分钟时基本恢复到缺血前的水平。丹参治疗组脑缺血时细胞外液Ｃｙｓ的含量较对照组低。结论Ｃｙｓ参与了脑缺血再灌注引起的损伤，而丹参可降低Ｃｙｓ水平，从而对缺血脑组织起到保护作用。     

Calcium-dependent component of massive increase in extracellular potassium during cerebral ischemia as demonstrated by microdialysis in vivo

This study characterizes the physiological features and limitations of K(+)-free dialysis to detect changes in extracellular concentration of K+ ([K+]e) in the rat hippocampus in vivo. It also demonstrates the effects of Ca(2+)-free perfusate containing Co2+ or Mg2+, which blocks Ca2+ entry into the presynaptic nerve terminal, on the abrupt increase in [K+]e detected by this technique during cerebral ischemia. K(+)-free dialysis for 40 min caused no significant changes in the baseline [K+]e. In contrast, Ca(2+)-free dialysis for 40 min significantly reduced the extracellular Ca2+ concentration. Under this condition, together with addition of Co2+ or Mg2+ to the perfusate, the increase in [K+]e was delayed, and a delay in reaching the maximum level was observed in a dose-dependent manner. These results are consistent with the hypothesis that the initial increase in [K+]e during cerebral ischemia is related to the Ca(2+)-dependent exocytotic release of neurotransmitters from depolarized nerve terminals.     

Extracellular dopamine in the rat striatum during ischemia and reperfusion as measured by in vivo electrochemistry and in vivo microdialysis

The effects of transient global forebrain ischemia and reperfusion on striatal extracellular dopamine levels were analyzed using both in vivo electrochemistry and in vivo microdialysis in urethane-anesthetized rats. Electrochemical records showed that extracellular dopamine levels increased once during the period of ischemia, and a second time during reperfusion. This biphasic pattern was not detected by microdialysis, probably because of the relatively low time resolution of this technique. Microdialysis provided evidence that the voltammetric signal was a measure of dopamine, and also allowed measurement of the metabolites dihydroxyphenylacetic acid and homovanillic acid, both of which decreased during ischemia. The biphasic dopamine pattern seen in rats is similar to that reported previously in gerbils, suggesting that it is a phenomenon common to transient ischemia and reperfusion across different species and models of transient global ischemia. This phenomenon may have important implications for therapeutic intervention in cerebral ischemia.     

Effect of nitro- -arginine on cerebral blood flow and monoamine metabolism during ischemia/reperfusion in the mongolian gerbil

Inhibition of nitric oxide synthase with nitro- -arginine (i.p., 40 mg/kg body weight) in contrast to -arginine (300 mg/kg body weight) delayed the initial recovery of cerebral blood flow (CBF) and altered dopamine (DA) metabolism in brain ischemia/reperfusion of Mongolian gerbils. Similar changes but more severe were observed with pargyline (monoamine oxidase inhibitor). Data suggest nitric oxide involvement in postischemic CBF recovery and modulation of DA metabolism due to nitro- -arginine-induced CBF reduction.     

Electron microscopic investigation of the cerebral cortex after cerebral ischemia and reperfusion in the gerbil

Prompt dendritic damage has been observed in the hippocampus of the gerbil brain after transient cerebral ischemia. In the present study, we studied the frontoparietal cortex of the gerbil brain electron microscopically after brief bilateral carotid occlusion to assess the vulnerability of dendritic processes. After ischemia for 5 min, there was swelling of the periphery of dendrites accompanied by swelling of mitochondria, cytoplasmic vacuolation and disintegration of microtubules in layer I, which spread to layer III after ischemia for 20 min. After reperfusion for 3-24 h following ischemia for 20 min, swelling in the periphery of dendrites and of mitochondria inside receded but vacuole formation and disintegration of microtubules propagated proximally. In neuronal perikarya, polyribosomal disaggregation was observed after ischemia for 20 min and persisted thereafter, while fragmentation of rough endoplasmic reticulum (ER) and microvacuolation occurred after reperfusion for 3 h. Electron-dense clumping of neuronal perikarya was observed after reperfusion for 6 h particularly in layers III and Vb, which increased in number for up to 72 h. The observed progressive damage in dendrites may be common to neurons vulnerable to cerebral ischemia and may significantly contribute to development of delayed neuronal death.     

脑缺血海马透析自由基活性研究

研究脑反复缺血再灌流羟自由基活性动态变化,探讨脑缺血损伤的病理生理机制。方法采用Ｐｕｌｓｉｎｅｌｌｉ和Ｂｒｉｅｆｌｅｙ４血管关闭方法,５ｍｉｎ×３次缺血,用微透析针植人右侧海马ＣＡ１区,用水杨酸盐捕获生成稳定的加合物２,３和２,５二氧苯甲酸（２,３和２,５ＤＨＢＡ）。用高压液相（ＨＰＬＣ）电化学检测。结果腹腔内注射水杨酸盐和微管透析针内注射水杨酸盐,２,３和２,５ＤＨＢＡ出现相似变化。缺血期２,３和２,５ＤＨＢＡ稍降低,灌流２０ｍｉｎ显著增高,灌流１ｈ升高至顶峰,持续３ｈ。证明脑反复缺血后再灌流羟自由基显著增高,并且不是一个暂时的现象。结论自由基在脑缺血损害中起重要作用。     

Ischemic tolerance and extracellular amino acid concentrations in gerbil hippocampus measured by intracerebral microdialysis

Preconditioning of the brain with sublethal ischemia induces tolerance to subsequent longer periods of ischemia. To elucidate the role of excitatory and inhibitory amino acids in the induction of ischemic tolerance, we measured the extracellular concentrations of the amino acids in the gerbil hippocampus with intracerebral microdialysis. Mongolian gerbils were subjected to 3 min of forebrain ischemia 4 days after preconditioning with 2 min of ischemia or sham operation. Microdialysis probes were implanted into the hippocampus before the second ischemia and the amino acid concentrations in the dialysates were measured with HPLC. During and immediately after 3 min of ischemia without preconditioning, the concentrations of glutamate, glycine, γ-aminobutyric acid, and taurine, but not glutamine, increased significantly. The increased amino acid levels rapidly returned to baseline after reperfusion. Preconditioning of the brain did not alter the amount of any amino acid released during and after the second ischemia. The excitotoxic index also unchanged in the preconditioned hippocampus. Thus, the results clearly show that ischemic tolerance is not induced through the alteration of the amounts of excitatory and inhibitory amino acids released during subsequent ischemia.     

脑缺血再灌流时脑温的动态改变

目的了解脑缺血再灌流后脑温的变化,为脑缺血动物的实验研究、以及亚低温脑保护作用机制提供理论依据。方法将SD大鼠分为四动脉阻断、双颈总动脉阻断、单侧颈总动脉阻断以及四动脉阻断10min、20min、30min后再灌流组。用点式测温仪同时测量不同部位脑组织的温度。结果脑组织内存在温度梯度;脑缺血后同一时间点纹状体、海马和颞肌的温度不一致;不同程度脑缺血后脑温的变化不一致,双侧颈总动脉阻断的脑缺血中脑温的改变呈波浪状,单侧颈总动脉阻断的脑缺血中缺血侧脑温低于对照侧;四动脉阻断的全脑缺血中,缺血后不同时间开始再灌流脑温都有回升现象;脑缺血的严重程度和持续时间可影响动物的清醒和脑温的变化。结论本实验的结果说明了在脑缺血实验研究时采用连续监测、并将脑温控制在特定的范围内,避免脑缺血和再灌流期间脑温的波动影响实验结果的准确性。