急性鼠脑缺血时选择性酶抑制剂的脑保护作用

目的 研究７－硝基吲唑（７－ＮＩ）在大鼠脑缺血后的保护作用。方法 用线栓法建立大鼠大脑中动脉缺血模型。用７－ＮＩ（选择性ｎＮＯＳ抑制剂）研究了鼠脑缺血过程中脑组织ＮＯＳ活性梗死体积以及梗死外周区神经元变化。结果 ７－ＮＩ明显抑制了神经元型ＮＯＳ活性,减少了脑梗死体积并显著减轻了神经元缺血早期变性变化。结论 ７－ＮＩ对因急性期脑组织有明显保护使用。     

7—nitro—indazole减小大鼠暂时性局灶性脑梗塞灶范围

目的探讨神经元型一氧化氮合酶（ｎＮＯＳ）在暂时性局灶性脑缺血中的作用。方法用栓线法建立了大脑中动脉阻塞（ＭＣＡＯ）模型的大鼠上，观察特异性ｎＮＯＳ抑制剂７－ｎｉｔｒｏ－ｉｎｄａｚｏｌｅ（７－ＮＩ）对大鼠缺血３ｈ、再灌注３ｈ脑梗塞灶范围的影响。结果７－ＮＩ（２５ｍｇ／ｋｇ）可减小大鼠脑梗塞灶范围，且主要减小大脑皮质梗塞灶，其作用可被Ｌ－精氨酸（３００ｍｇ／ｋｇ）逆转，Ｄ－精氨酸（３００ｍｇ／ｋｇ）则否。结论ｎＮＯＳ产生的ＮＯ在暂时性局灶性脑缺血中起损害作用     

神经元型一氧化氮合酶在学习记忆过程中的变？…

目的 探讨神经元型一氧化氮合酶（ｎｅｕｒｏｎａｌ ｎｉｔｒｉｃ ｏｘｉｄｅ ｓｙｎｔｈａｓｅ,ｎＮＯＳ）及一氧化氮（ｎｉｔｒｉｃ ｏｘｉｄｅ,ＮＯ）在学习记忆机制中的相关作用。方法 采用免疫组化方法观察Ｙ迷宫空间辨别学习训练后大鼠不同脑区ｎＮＯＳ表达变化,并探讨特异性ｎＮＯＳ抑制剂７－ｎｉｔｒｏ ｉｎｄｏｚａｌ（７－ＮＩ）、钙拮抗剂尼莫通（ｎｉｍｏｔｏｐ）腹腔注射对大鼠学习获得和记忆再能能力的影响     

大鼠急性局灶性脑缺血再灌注脑组织NO含量和NOS活性的变化

目的探讨一氧化氮（ＮＯ）和神经元型ＮＯ合酶（ｎＮＯＳ）是否参与急性局灶性脑缺血再灌注的发病机理。方法采用栓红法建立大鼠大脑中动脉阻塞（ＭＣＡＯ）模型,观察脑组织ＮＯ含量和一氧化氮合酶（ＮＯＳ）活性的变化及ｎＮＯＳ抑制剂７－硝基吲唑（７－ＮＩ）对再灌注期两者的影响。结果缺血３０分种ＮＯ含量和ＮＯＳ活性显著升高,缺血３小进两者下降;再灌注３０分种ＮＯＴ和ＮＯＳ再次升高,而再灌注３小时两者又下降。７－Ｎ     

一氧化氮与帕金森病大鼠模型神经损伤的研究

目的 研究一氧化氮（ＮＯ）在帕金森病（ＰＤ）大鼠模型神经损伤中的作用。方法 用高效液相色谱电化学法（ＨＰＬＣ－ＥＴ）及还原型辅酶Ⅱ（ＮＡＤＰＨ）黄递酶组化法观察ＮＯ在ＰＤ大鼠模型神经损伤中的作用。结果 神经型一氧化氮合成酶（ｎＮＯＳ）抑制剂７－硝基吲唑（７－ＮＩ）明显减少６－羟基多巴胺（６－ＯＨＤＡ）引起的纹状体多巴胺及其代谢产物的降低（Ｐ〈０．０１）；纹状体ＮＡＤＰＨ黄递酶阳性神经元可抵抗６－Ｏ     

iNOS抑制剂对海马缺血/再灌注损伤保护作用研究

目的：进一步证实诱导型一氧化氮合酶（ｉＮＯＳ）催化所形成的一氧化氮（ＮＯ）在脑缺血／再灌注损伤中具有毒性作用。方法：将Ｓ－Ｄ大鼠双侧颈总动脉短暂夹闭３分钟,然后分成应用药物组－氨基胍（ＡＧ）和非药物组．４８小时后取海马脑片,观察顺向群峰电位（ｏＰＳ）以及组织学改变。结果;给药组大部分可见ｏＰＳ发放．而对照组只见有突触前排放（ｐｖ）无ｏＰＳ（Ｐ＜０．０５）,两组超微结构也有明显差异。结论：本实验证明大鼠海马短暂缺血／再灌注后ｉＮＯＳ抑制剂可减轻神经元损害,即可抑制血由ｉＮＯＳ诱生表达所形成的ＮＯ在脑缺血／再灌注损伤中的毒性作用。     

海人酸致痫动物模型脑内一氧化氮,一氧化氮合酶的变化

目的探讨一氧化氮（ＮＯ）、一氧化氮合酶（ＮＯＳ）在癫痫发生中的作用及ＮＯＳ抑制剂的作用。方法采用海人酸致痫大鼠模型并应用ＮＯＳ抑制剂Ｌ－硝基精氨酸甲酯（Ｌ－ＮＡＭＥ）,分别在致痫后３０分钟、６０分钟取海马组织,匀浆后测定ＮＯ及ＮＯＳ水平。结果致痫３０分钟后海马ＮＯ含量显著升高,至６０分钟恢复正常;ＮＯＳ活性水平增高＞５０％;Ｌ－ＮＡＭＥ明显抑制大鼠的痫性发作,应用ＮＯＳ抑制剂组大鼠海马ＮＯ、ＮＯＳ含量明显下降。结论癫痫发作后脑内ＮＯ、ＮＯＳ活性增强,ＮＯＳ抑制剂通过抑制酶活性使ＮＯ生成降低,并完全抑制痫性发作。ＮＯＳ活性受抑制＞４８％即可产生明显效果。提示ＮＯ可能有内源性致痫作用。     

巴曲酶对海马脑片缺氧损伤的保护作用

本实验采用离体大鼠海马脑片缺氧模型，观察巴曲酶对缺氧后海马脑片ＣＡ１区诱发突触电位的影响。结果可见：用三种浓度巴曲酶孵育的海马脑片缺氧后ＰＶ消失时间均明显延迟，但对ＰＳ的消失时间无明显影响。提示：巴曲酶对海马神经元缺氧损伤具有一定保护作用。     

尼古丁对帕金森病小鼠脑组织一氧化氮合酶活性的影响

帕金森病 (ＰＤ)的主要病理变化为黑质纹状体多巴胺(ＤＡ)能神经元变性 ,其病因及发病机制尚不明确。有研究发现 ,应用甲基 苯基 四氢吡啶 (ＭＰＴＰ)制作的ＰＤ小鼠脑组织神经元型一氧化氮合酶 (ｎＮＯＳ)活性增高 ,认为一氧化氮(ＮＯ)参与了ＭＰＴＰ的神经毒作用。某些流行病学及生物学资料表明 ,吸烟对ＰＤ的发病具有保护作用 ,但其作用机制尚不清楚。本实验采用雄性Ｃ5 7ＢＬ小鼠腹腔注射ＭＰＴＰ建立小鼠ＰＤ模型 ,观察尼古丁对ＰＤ小鼠脑组织ｎＮＯＳ活性的影响 ,以探讨尼古丁对ＭＰＴＰ神经毒性的可能保护机制。材料和方法 :选用 8周…     

一氧化氮与帕金森病小鼠模型神经损害的研究

目的　研究一氧化氮（ＮＯ） 在帕金森病（ＰＤ）小鼠模型神经损害中的作用。方法　用比色分析、高效液相色谱电化学及免疫组化法检测１甲基４苯基四氢吡啶（ＭＰＴＰ）和７硝基吲唑（７ＮＩ）对Ｃ５７ＢＬ小鼠纹状体一氧化氮合酶（ＮＯＳ） 活性,多巴胺（ＤＡ）、二羟基苯乙酸（ＤＯＰＡＣ）、高香草酸（ＨＶＡ） 水平和酪氨酸羟化酶（ＴＨ） 免疫阳性神经纤维的影响。结果　注射ＭＰＴＰ后Ｃ５７ＢＬ小鼠纹状体ＮＯＳ活性增加,７ＮＩ能明显抑制ＭＰＴＰ引起的ＮＯＳ活性的升高（ 分别为０ ．９３ ±０．２４ 和０．５４ ±０．１６,ｎｍｏｌ·ｍｉｎ－１·ｇ－１ 组织,Ｐ＜０．０１） 。７ＮＩ能明显减轻ＭＰＴＰ引起的Ｃ５７ＢＬ小鼠纹状体ＤＡ（ 分别为０ ．８ ±０ ．２ 和６．８±０．５,μｇ／ｇ 组织,Ｐ＜０．０１） 、ＤＰＯＡＣ（ 分别为０．３ ±０．１ 和０ ．９ ±０ ．３ ,μｇ／ｇ 组织,Ｐ＜ ０ ．０１）、ＨＶＡ（分别为０．４±０．２ 和０．９ ±０ ．２,μｇ／ｇ 湿组织,Ｐ＜ ０．０１） 的降低及ＴＨ 阳性神经纤维损害。结论神经元来源的ＮＯ 参与了ＭＰＴＰ的毒性机制,神经元型ＮＯＳ抑制剂可能有益于ＰＤ的治疗。     

Nitric oxide is involved in anoxic preconditioning neuroprotection in rat hippocampal slices

Sublethal anoxia/ischemia protects against subsequent damaging insults in intact brain or hippocampal slices. To help further understand mechanisms underlying anoxic/ischemic preconditioning, we tested three hypotheses which were that: (a) anoxic preconditioning (APC) improves electrical recovery in rat hippocampal slices; (b) anoxic preconditioning requires nitric oxide (NO); and (c) anoxic preconditioning blocks mitochondrial dysfunction that occurs following re-oxygenation after anoxia. Control hippocampal slices underwent a single 'test' anoxic insult. Experimental slices were preconditioned by 3 short anoxic insults prior to the 'test' insult. Evoked potentials (EPs), and NADH redox status were recorded prior to, during and after preconditioning and/or 'test' anoxic insults. To examine the role of NO, studies sought to determine whether APC could be produced by the NO donor, DEA/NO, and whether APC could be inhibited by NO synthase (NOS) inhibitor (7-nitroindazole). EP amplitudes recovered significantly better after reoxygenation in preconditioned slices and after NO-emulated preconditioning (90.0+/-17.7% and 90.0+/-21.3%, respectively, n=9, ** p<0.01, vs. 17.0+/-7.9%, n=9, in control slices). Inhibition of NOS blocked APC protection (6.8+/-6.8%, n=9). The intensity of NADH hyperoxidation was not significantly different among groups following 'test' anoxia. These data confirm that preconditioning by anoxia improves electrical recovery after anoxia in hippocampal slices. Evidence supports that NO from constitutive hippocampal NOS may be involved in the neuroprotection afforded by preconditioning by a mechanism that does not change the apparent mitochondrial hyperoxidation after anoxia.     

ATP敏感性K^＋通道在海马缺氧损伤中的作用

目的研究ATP敏感性K 通道阻断剂glipizide（GLI）对缺氧后海马脑片损伤以及海马神经元[Ca(2 )]i变化的影响。方法以大鼠离体海马脑片和体外分散培养的海马神经元为标本，分别采用电生理微电极记录技术以及激光扫描共聚焦显微镜监测神经元[Ca(2 )]i的方法。结果预先用GLI（20μmol／L）灌流的海马脑片缺氧后PV持续时间较对照组显著缩短，提示其加重了海马不可逆缺氧损伤的发生；另外急性缺氧可诱导海马神经元[Ca(2 )]i迅速升高，而预先加入GLI（20μmol／L）能显著加剧[Ca(2 )]i的升高程度。结论ATP敏感性K 通道在缺氧过程中的开放对大鼠海马脑区具有重要的保护作用，它可显著降低缺氧所致神经元[Ca(2 )]i升高，提高海马脑片的抗缺氧能力。这可能是其对抗海马缺氧损伤的主要作用机制之一。     

Calcium and increase excitability promote tolerance against anoxia in hippocampal slices

We have previously demonstrated that anoxic preconditioning (APC) protects against a subsequent otherwise 'lethal' anoxic insult in hippocampal slices. Tested here are two hypotheses: (a) APC requires calcium to improve electrical recovery in hippocampal slices; and (b) mild excitation promotes preconditioning neuroprotection. Control hippocampal slices were given a single 'test' anoxic insult followed by reoxygenation. Experimental slices were preconditioned by three short anoxic insults of 1 min separated by 10 min of reoxygenation. At 30 min after the third 'conditioning' insult, slices underwent a 'test' anoxic insult [1 min of anoxic depolarization (AD)], and then slices were reoxygenated. Evoked potentials (EPs) were recorded throughout the experiment. In other slices, APC was emulated by inducing spreading depression (as determined by a negative DC shift) with KCL or by inducing increased neuronal excitability with the excitatory agent 8-cyclopentyl-1, 3-dipropylxanthine (DPCPX) (an adenosine A1 receptor blocker). 'Test' anoxic insults lasted 2 min of AD in these groups. To determine the role of calcium during APC, extracellular CaCl2 was decreased to 0.5 mM but only during the APC episodes ('test' anoxia, 1 min of AD). EP amplitudes recovered significantly better after anoxia in preconditioned slices, and in KCl- and DPCPX-treated slices (147.2+/-33.3, n=8, **p<0.01, 71.7+/-13.5, n=7, **p<0.01, and 117.8+/-37.3, n=5, ***p<0.001, respectively) compared to controls. Decreases in extracellular CaCl2 during APC blocked the recovery of EPs after 'test' anoxia (80.6+/-23.0, n=8). These data confirm that increases in excitability can emulate APC. These data also demonstrate that calcium influx during preconditioning is required for the induction of tolerance during APC.     

Glucose enhances recovery of potassium ion homeostasis and synaptic excitability after anoxia in hippocampal slices

Hippocampal slices exposed to brief anoxia combined with elevated glucose exhibit greater postanoxic recovery of synaptic transmission. Glucose may have improved recovery of synaptic transmission by enhancing the production of metabolic energy during and after anoxia. This enhancement should provide more ATP for energy-requiring ion transport processes, and lead (1) to a delayed onset of complete depolarization of CA1 pyramidal cells during anoxia (anoxic depolarization) and (2) to greater ion transport activity following anoxia. A delay in anoxic depolarization would protect neurons from damage if the duration of anoxic depolarization was shortened. Greater postanoxic ion transport would allow the re-establishment of ion gradients supportive of neuronal and synaptic excitability. The effects of glucose and anoxia on ion homeostasis and synaptic transmission were examined in rat hippocampal slices exposed to different glucose concentrations (5–20 mM). The duration of anoxic depolarization was held constant so that postanoxic damage related to this duration was controlled. We found that K⁺ transport and recovery of synaptic transmission after anoxia in hippocampal slices improved as glucose concentration increased. Also, anoxic depolarization was delayed as glucose concentration increased. Thus, added glucose may improve postanoxic recovery of synaptic transmission by better supporting ion transport.     

神经元型一氧化氮合酶在学习记忆过程中的变化和作用

目的　探讨神经元型一氧化氮合酶 (neuronalnitricoxidesynthase,nNOS)及一氧化氮 (nitricoxide ,NO)在学习记忆机制中的相关作用。方法　采用免疫组化方法观察Y迷宫空间辨别学习训练后大鼠不同脑区nNOS表达变化 ,并探讨特异性nNOS抑制剂 7 nitroindozal(7 NI)、钙拮抗剂尼莫通 (nimotop)腹腔注射对大鼠学习获得和记忆再现能力的影响。结果　学习训练后海马各亚区nNOS样神经元数量及染色强度明显增加 ,而皮层和纹状体区则无显著变化 ;7 NI以剂量依赖方式损伤大鼠的学习获得能力 ,但不影响记忆再现 ,尼莫通则对这两种能力均有破坏。结论　提示学习记忆过程可能伴有nNOS合成及活性增加 ,nNOS/NO在学习获得阶段具有重要作用。     

Antioxidants, mitochondrial hyperoxidation and electrical recovery after anoxia in hippocampal slices

Cerebral injury may occur not only during brain ischemia but also during reperfusion afterward. A characteristic event during reperfusion after cerebral ischemia, or reoxygenation after anoxia in hippocampal slices, is hyperoxidation of the electron carriers of the mitochondrial respiratory chain. Earlier studies suggested that mitochondrial hyperoxidation was produced by an oxyradical mechanism and was linked to neuronal damage. Present studies sought to test this hypothesis by determining whether antioxidants could suppress mitochondrial hyperoxidation and improve electrical recovery after anoxia in hippocampal slices. Both 500 μM ascorbate and 50 μM glutathione decreased post-anoxic hyperoxidation of NADH and improved electrical recovery in hippocampal slices. These data support a role of oxygen free radicals in promoting post-anoxic mitochondrial hyperoxidation and electrical failure, and suggest that these effects of anoxia or ischemia may be linked.     

依达拉奉对脑缺血再灌注大鼠海马一氧化氮的影响

目的研究依达拉奉对脑缺血再灌注大鼠海马一氧化氮(NO)产生的影响。方法大鼠脑缺血采用四血管阻断法,选择性测定电极检测的浓度。实验分为生理盐水组、依达拉奉组(Edaravone)和7-Nitroindazole(7-NI)组。结果依达拉奉和7-NI皆未影响大鼠的血压和海马血流量,均显著减少了缺血再灌注时海马内NO的产生(均P<0.001)。结论依达拉奉可能通过抑制神经型一氧化氮合酶(nNOS)或减少NO而起到神经保护作用。     

Effect of alpha-tocopherol and free radicals on anoxic damage in the rat hippocampal slice

The effect of alpha-tocopherol on irreversible transmission loss subsequent to anoxia was examined using the hippocampal slice preparation. A population spike was recorded from the dentate granule cell layer after stimulation of the perforant path. The amplitude of the population spike was compared before and after anoxia. Control slices recovered to 22 +/- 7% of their preanoxic amplitude after 7 min of anoxia. Slices treated with alpha-tocopherol showed significantly greater recovery after anoxia (P less than 0.001). The population spike recovered to 64 +/- 15% of its preanoxic amplitude. As alpha-tocopherol is a free radical scavenger, our results provide evidence that free radicals are partly responsible for irreversible anoxic damage. alpha-Tocopherol is not toxic and may prove efficacious in protecting the brain against anoxic damage.