人重组白细胞介素-6对缺氧后海马培养神经细胞Fos表达的影响

用免疫组化方法，观察缺氧诱导体外培养大鼠海马神经细胞Fos表达及人重组白细胞介素-6（rhIL－6）的影响。结果显示，经rhIL－6孵育的海马神经细胞缺氧后Fos免疫反应阳性胞核的百分率和Fos免疫反应阳性胞核的平均光密度均明显低于对照组，表明缺氧能诱导体外培养海马神经细胞Fos的表达，rhIL－6能抑制缺氧神经细胞Fos的表达。提示rhIL-6可能参与脑缺氧损伤的调控。     

低氧预处理对大鼠海马神经元缺氧耐受性和IL-6免疫反应的影响

目的 观察低氧预处理对大鼠海马神经元缺氧耐受性和IL-6免疫反应的影响。方法 取培养12d的两组（对照组和低氧预处理组）培养神经元,同时置于缺氧环境（0.9L/LN2、0.1L/LCO2)中培养2、4、8和12两组（对照组和低氧预处理组）培养神经元,同时置于缺氧环境（0.9L/LN2、0.1L/LCO2)中培养2、4、8和12h,分别观察它们的形态变化和神经元存活数,并用抗rhIL-6单克隆抗体进行免疫组化染色,观察缺氧对大鼠海马培养神经元IL-6免疫反应的影响。结果 低氧预处理可增强海马神经元对rhIL-6的免疫反应,经低氧预处理的海马神经元缺氧后神经元存活数和对rhIL-6的免疫反应均明显高于对照组。结论 低氧预处理氧预处理的海马神经元缺氧后神经元存活数和对thIL-6的免疫反应均明显高于对照组。结论 低氧预处理可使体外培养的海马神经元对缺氧产生耐受,其中rhIL-6的免疫反应增加可能是海马神经元对缺氧的一种适应性变化,提示IL-6可能参与脑缺氧耐受性的形成,并在海马神经元缺氧损伤的调控中起重要作用。     

人重组白细胞介素-6对大鼠海马神经元Bcl-2表达的影响

观察重组人白细胞介素－6（rhIL－6）对体外培养大鼠海马神经元Bcl－2表达的影响。方法取培养3、7、14、21和28天（d）的两组（对照组和rhIL－6组）培养神经元,分别观察其生长发育和神经元活存数,并用抗Bcl－2抗血清进行免疫组化染色,观察Bcl-2免疫反应（Bcl-2－IR）阳性和阴性神经元数目,计算Bcl-2－IR阳性神经元所占百分率,并在图像分析仪上对Bcl-2－IR神经元作平均光密度的色谱分析。结果培养3、7、14、21和28d时,rhIL－6组神经元活存数、Bcl－2－IR阳性神经元数和Bcl-2-IR阳性神经元的平均光密度均明显高于对照组。结论rhIL－6能增强生长发育过程中海马神经元Bcl-2的表达,减少神经元的退化死亡,表明rhIL-6对体外培养的海马神经元具有神经营养作用。     

降钙素基因相关肽对缺氧时大鼠海马培养神经元c—fos表达的影响

采用免疫组化（ABC）方法，观察缺氧诱导体外培养大鼠海马神经元c-fos的表达及降钙素基因相关肽（CGRP）的影响。结果显示，缺氧后海马神经元中Fos-免疫反应（Fos—IR）阳性胞核百分率随缺氧时间的延长而逐渐增多，图像分析的结果显示，缺氧后Fos—IR阳性胞核的平均失密度亦随缺氧时间的延长而逐渐增强。经CGRP孵育的海马神经元缺氧后Fos-IR阳性胞核的百分率和Fos-IR阳性胞核的平均光密度均明显低于非CGRP孵育组。本结果表明，缺氧能诱导体外培养海马神经元。c-fos的表达，神经肽CGRP能抑制缺氧海马神经元c-fos的表达。提示CGRP对海马神经元缺氧损伤可能具有一定保护作用。     

人重组白细胞介素—6对缺氧对后海马培养神经…

用免疫组化方法，观察缺氧诱导体外培养大鼠海马神经细胞Ｆｏｓ表达及人重组白细胞介素－６（ｒｈＩＬ－６＿的影响。结果显示，经ｒｈＩＬ－６卵育的海马神经细胞缺氧后Ｆｏｓ免疫反应一胸核的百分率和Ｆｏｓ反应阳性胸核的平均光密度均明显低于对照组，表明缺氧能诱导体外培养海马神经细胞Ｆｏｓ的表达，ｒｈＩＬ－６能抑制缺氧神经细胞Ｆｏｓ的表达。提示ｒｈＩＬ－６可能参与脑缺氧损伤的调控。     

人胚海马神经干细胞体外培养及分化研究

目的 研究人胚胎海马神经干细胞体外长期培养的条件和其在自主分化条件下的分化能力和分化特点。方法 从人胚胎海马分离神经干细胞。采用无血清培养法，进行体外培养、扩增，形成神经球。使神经球贴壁分化，分化培养基不含有任何细胞有丝分裂促进剂。使用5-溴脱氧尿嘧啶核苷(BrdU)标记分裂增生的细胞，观察细胞的分裂增殖情况。使用免疫细胞化学法鉴定神经干细胞及其在不加诱导剂下的自主分化能力。结果 从人胚胎海马分离的神经干细胞具有增殖能力，细胞倍增时间为3．2d。BrdU检测有正在分裂、增殖的细胞。细胞贴壁分化后可以出现Nestin、GFAP、Tuj-1表达阳性的细胞。神经干细胞共培养6个月，传代14代。结论 分离培养的海马神经干细胞具有自我更新和增殖能力，可以长期培养。在不加任何诱导剂的自主分化条件下可以向神经元、胶质细胞分化。少突胶质细胞的培养需要不同的培养条件。分离培养的干细胞具有神经干细胞的特征。可用于基础和临床的相关研究。     

缺血缺氧对体外培养星形胶质细胞细胞周期和增殖的影响

目的 观察缺血缺氧损伤对星形胶质细胞细胞周期和增殖的影响。方法 用流式细胞仪检测缺血缺氧后不同时问点星形胶质细胞细胞周期变化，并用荧光免疫细胞化学技术测定胶质细胞纤维酸性蛋白(GFAP)和增殖细胞核抗原(PCNA)的表达水平。结果 体外缺血缺氧损伤后星形胶质细胞S期较正常组明显增高，6h达高峰，而随后则呈下降趋势。PCNA阳性反应损伤后表达均增加，6h表达最高；在缺血缺氧早期，GFAP阳性染色增强，6h最高；缺血缺氧12h后GFAP阳性染色变弱。结论 缺血缺氧损伤后星形胶质细胞活化进入增殖期；PCNA参与了损伤后星形胶质细胞的修复和增殖；细胞周期事件与星形胶质细胞的活化密切相关。     

星形胶质细胞在实验性癫痫中的作用及意义探讨

目的 探讨星形胶质细胞在实验性癫痫中的作用及意义。方法 建立大鼠杏仁核点燃癫痫模型．应用免疫组化方法检测大鼠点燃癫痫后海马及颞叶GFAP免疫反应阳性细胞。并测定其细胞数、面积、周长、积分光密度。结果 实验组海马回和颞叶皮层GFAP免疫反应阳性的胶质细胞与对照组和手术对照组相比，数量明显增多、胞体截面积增大、突起及其分支增多、GFAP免疫反应性增强。结论 星形胶质细胞的增多是癫痫后脑损伤的代偿结果，另一方面．又可以反过来成为影响癫痫病程发展的原因。     

LPS刺激神经胶质细胞条件培养上清诱导神经元凋亡

目的研究经脂多糖(LPS)刺激后神经胶质细胞培养上清对神经元死亡及凋亡的诱导情况。方法体外原代培养小鼠混合神经胶质细胞和神经元细胞,采用LPS刺激神经胶质细胞,24h后收获条件培养上清与神经元细胞共孵育,检测神经元细胞死亡和凋亡的情况。结果 LPS刺激后的神经胶质细胞培养上清对神经元的毒性作用与未刺激组无明显差别(P>0.05);LPS刺激后的神经胶质细胞条件培养上清诱导神经元细胞凋亡明显高于未刺激组(P<0.05)。结论神经胶质细胞LPS刺激后的条件培养上清可以诱导神经元凋亡,但没有导致明显的神经元细胞死亡。     

缺血缺氧对体外培养星形胶质细胞细胞周期和周期相关蛋白的影响

目的 观察缺血缺氧损伤对星形胶质细胞细胞周期及细胞周期相关蛋白的影响。方法 用流式细胞仪及Brdu掺入法检测缺血缺氧后不同时间点星形胶质细胞细胞周期变化和细胞的增殖活力；用荧光免疫细胞化学技术测定增殖细胞核抗原(PCNA)及细胞周期蛋白cyclin D1的表达水平。结果 体外缺血缺氧损伤后S期星形胶质细胞较正常组明显增加，6h达高峰，Brdu掺入法显示损伤后6h星形胶质细胞的增殖活力最高，而随后S期细胞数目及细胞增殖活力都呈下降趋势。PCNA阳性反应损伤后表达增加，6h表达最高，而cyclin D1的表达在损伤后逐渐增加，在24h时达高峰。结论 缺血缺氧损伤激活星形胶质细胞，使其进入新的细胞周期，出现细胞的增殖反应；PCNA及cyclin D1参与了损伤后星形胶质细胞的修复和增殖；细胞周期事件与星形胶质细胞的增殖活化密切相关。     

在缺氧条件下培养的海马神经元形态结构及热休克蛋白(HSP)70表达变化及丹参的影响

在体研究曾发现在缺血再灌注模型中，丹参具神经保护作用。本文采用新生大鼠海马神经元培养技术，以细胞形态学及HSP70免疫性细胞表达为指标，首次观察了缺氧条件下培养的海马神经无形态结构及HSP70表达变化及丹参的影响。结果发现：（1）不论缺氧1h或2h，在培养的海马神经细胞中，有的细胞出现细胞体周围光晕消失，胞浆内颗粒变性，细胞膜肥厚、粗糙，轴突变粗、断裂，并且出现HSP70免疫阳性细胞；（2）缺氧1h组的海马神经细胞存活率及HSP70免疫阳性细胞率均显著高于缺氧2h组，（3）丹参组（在缺氧0．5h前给丹参100mg／ml（终浓度）的海马神经细胞存活率及HSP70免疫阳性细胞率均显著高于缺氧2h组。结果提示丹参具有直接的抗缺氧性神经细胞损伤的作用，减轻了缺氧所造成的神经细胞形态学上的改变。     

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.     

Subcellular immunolocalization of NMDA receptor subunit NR-1 in the chinchilla vestibular periphery

The effect of brief anoxia on voltage dependent K(+)-currents of hippocampal cultured neurons was studied. The oxygen scavenger dithionite (hydrosulphite) was previously used for creating zero oxygen pressure. However, dithionite consumes O(2) in parallel with generation of superoxide radicals and is a strongly reducing agent. In this study anoxia was produced by perfusion of the neurons with a solution bubbled with nitrogen for 1 h using a chamber with an argon layer isolating the anoxic bath flow from atmospheric oxygen in presence and absence of dithionite. Oxygen partial pressure of dithionite-free solution was determined by oxygen dependent quenching of the phosphorescence of Pd-coproporphyrin to be 0.15+/-0. 02 Torr (values are given as mean+/-S.D., n=6). Slow (I(K))- and fast (I(A))-inactivating K(+)-currents were measured with the patch clamp technique in the whole cell configuration. Exposure of the neurons to anoxia reversibly decreased the amplitude of I(K) at a test pulse of 0 mV to 77+/-12% (n=7) in absence and to 83+/-7% (n=6) in presence of 2 mM dithionite; the amplitude of I(A) decreased to 78+/-11% in absence and to 82+/-9% in presence of 2 mM dithionite. Voltage dependence of activation and inactivation shifted 5 min after exposure to anoxia reversibly by about 6 mV in depolarizing direction. The decay times of inactivation were insensitive to anoxia. Dithionite had no significant effects on K(+)-currents. In 15 of 21 neurons not employed for analysis on K(+)-currents, a reversible increase in holding current under dithionite was observed. In absence of dithionite in 4 of 19 neurons the holding current reversibly increased during anoxia. Although dithionite does not affect K(+)-currents, changes in holding current show that the dithionite may affect neurons independently of oxygen deprivation.     

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。     

Expression of thymosin beta in the rat brain following transient global ischemia

Thymosin beta (Tbeta) isoforms play an important role in the organization of the cytoskeleton by sequestering G-actin during development of the mammalian brain. In this study, we examined changes in the expression of Tbeta4 and Tbeta15 after transient global ischemia. Tbeta15 mRNA increased gradually in the dentate gyrus (DG) of the hippocampal formation from 3 h after reperfusion and peaked 9 h later. Similarly, a significant increase in Tbeta4 mRNA level was observed in the DG 12 h after reperfusion. Tbeta4 and Tbeta15 proteins were found in different cell types in control brains; Tbeta15 was expressed in a subset of doublecortin (DCX)-positive cells in the DG, whereas Tbeta4-IR was observed in DG neurons and nearby microglial cells. After ischemia, Tbeta15-IR was found in DG neurons and Tbeta4-IR in the reactivated microglial cells. Interestingly, Tbeta15-IR accumulated in the nuclei of CA1 neurons, which are vulnerable to ischemic insults. These results suggest that Tbeta4 and Tbeta15 function in different cellular contexts during ischemia-induced responses.     

The N-methyl-D-aspartate antagonists aminophosphonovaleric acid and MK-801 reduce anoxic damage to dentate granule and CA1 pyramidal cells in the rat hippocampal slice

The effect of the N-methyl-D-aspartate antagonists, aminophosphonovaleric acid and MK-801, on irreversible transmission loss subsequent to anoxia was examined using the hippocampal slice preparation. A population spike was recorded from either the dentate granule cells or the CA1 pyramidal cells and the amplitude of this spike was compared before and 60 min following anoxia. After 10 min of anoxia the dentate granule cells recovered to 16 +/- 7% (mean +/- SE) of their preanoxic level when untreated and to 54 +/- 15% when treated with aminophosphonovaleric acid (APV). In slices treated with MK-801 the population spikes recorded from dentate granule cells recovered to 85 +/- 4% of their preanoxic level after 10 min of anoxia. Untreated CA1 pyramidal cells recovered to 8 +/- 3% of their preanoxic amplitude after 5 min of anoxia; they recovered to 59 +/- 6% when treated with MK-801 and 31 +/- 13% when treated with APV. The recovery of slices treated with the drugs was significantly different from that of untreated slices. ATP levels were measured in both the dentate and the CA1 region of slices. ATP in both regions fell less during anoxia when the slices were pretreated with either APV or MK-801. These differences between drug-treated and untreated tissue were significant with APV and MK-801. These differences between drug-treated and untreated tissue were significant with APV and MK-801 in dentate tissue after 10 min of anoxia and with MK-801 in CA1 tissue after 5 min of anoxia. This reduced fall in ATP during anoxia was accompanied by better physiological recovery after anoxia. We conclude that these NMDA antagonists provide protection against anoxic damage to dentate granule and CA1 pyramidal cells in this in vitro hippocampal preparation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nitric Oxide Signalling is Required for the Generation of Anoxia-induced Long-term Potentiation in the Hippocampus

The involvement of nitric oxide in anoxia-induced long-term potentiation (anoxic LTP) of synaptic transmission was investigated in CA1 neurons of rat hippocampal slices using intracellular recording techniques in vitro . In response to superfusion of an anoxic artificial cerebral spinal fluid saturated with 95% N₂-_-5% CO₂, the excitatory postsynaptic potential (EPSP) generated in hippocampal CA1 neurons by stimulation of the Schaffer collateral/commissural afferent pathway was completely abolished within 10 min of anoxia. On return to reoxygenated medium, the EPSP returned to the control value within 10 min and was subsequently and progressively potentiated to reach a plateau 15–20 min after return to oxygen. This anoxia-induced persistent increase in synaptic transmission lasted for more than 1 h. Application of the nitric oxide synthase inhibitors 7-nitroindazole (7-NI) or l- N ^G-nitroarginine (NOARG) produced no effects on the baseline EPSP amplitude, but effectively attenuated the anoxic LTP. The inhibitory effects of both 7-NI and NOARG on the anoxic LTP were blocked by l-arginine, a substrate for nitric oxide synthase. These results suggest that nitric oxide is required for the generation of anoxia-induced LTP of glutamatergic synaptic transmission in the CA1 region of the rat hippocampus.     

Calcium-sensitive recovery of extracellular potassium and synaptic transmission in rat hippocampal slices exposed to brief anoxia

We examined the possibility that Ca2+-sensitive inhibition of synaptic transmission following anoxia involves compromise of ion transport activity. Rat hippocampal slices were superfused with artificial cerebrospinal fluids containing different concentrations of CaCl2, and subjected to short anoxia. Durations of anoxia were sufficient to provoke anoxic depolarization, indicated by a sudden rise in extracellular K+ (K+o). Following anoxia, apparent K+ transport was assessed by measuring the magnitude of subnormal K+o (the K+o undershoot) in hippocampal region CA1. Recovery of synaptic transmission 1 h after anoxia was determined by evaluation of the magnitudes of the orthodromically stimulated population spike recorded from CA1 pyramidal cells. K+o undershoots and recovery of synaptic transmission decreased as CaCl2 or the duration of anoxic depolarization increased. These data suggest: (1) that increased artificial cerebrospinal fluid CaCl2 compromised K+ reaccumulation after anoxia; and (2) that ion transport dysfunction may inhibit recovery of synaptic transmission.