胸髓上段交感节前神经元在椎动脉型颈椎病模型发病中的调控机制

目的　探索交感神经受刺激在CSA发病中的调控作用。方法　 2 0只家兔随机分为两组 :模型组和正常组 ,模型组通过外载荷力的作用 ,制作CSA动物模型。采用玻璃微电极胞外记录方法 ,测量SPNs自发和诱发放电脉冲数。结果　模型组胸髓侧角的SPNs放电次数明显多于正常组 (P <0 0 0 1)。结论　椎动脉型颈椎病时交感神经活性的增加、放电次数增多可能是导致椎动脉痉挛、供血不足的主要原因。     

An improved loose patch voltage clamp method using concentric pipettes

A method for noninvasive voltage-clamp recording from large cells is described. A firepolished pipette having two concentric barrels is pushed against the cell membrane, thereby electrically isolating a circular patch subdivided into an inner and an annular outer region. Both regions are held isopotential, but current is collected from the inner region only. The method electrically simulates a high resistance seal between pipette and cell membrane, allowing accurate and rapid voltage-clamp recording under conditions where the seal resistances actually obtained are low (near 1 M). This is useful in applications where one wishes to avoid enzymatic treatment.We provide details of electrode construction and voltage-clamp electronics, and present results obtained from frog skeletal muscle and leech neurons. For sodium channels of frog muscle, extensive data were previously obtained with other methods. There is good agreement between the earlier results and the measurements presented here.     

Beta-amyloid25-35 inhibits glutamate uptake in cultured neurons and astrocytes: modulation of uptake as a survival mechanism

Glutamate transporters are vulnerable to oxidants resulting in reduced uptake function. We have studied the effects of beta-amyloid(25-35) (beta A(25-35)) on [(3)H]-glutamate uptake on cortical neuron or astrocyte cultures in comparison with a scrambled peptide (SCR) and dihydrokainic acid (DHK), a prototypic uptake inhibitor. beta A(25-35) was more potent than DHK in inhibiting glutamate uptake and the effects of both were more marked on astrocytes than on neurons. At 24 h, beta A(25-35) dose-dependently (0.5-15 microM) increased glutamate levels in media from neuron cultures. DHK only enhanced extracellular glutamate at the highest concentration tested (2500 microM). beta A(25-35) induced gradual neurotoxicity (0.1-50 microM) over time. Exposure to beta A(25-35) resulted in increased uptake in astrocytes (0.25-5 microM) and neurons (0.5-15 microM) surviving its toxic effects. However, exposure to DHK (2.5-2500 microM) did not induce neurotoxicity nor modulated uptake. These results indicate that, while inhibition of glutamate uptake may be involved in the neurotoxic effects of beta A(25-35), enhancement of uptake may be a survival mechanism following exposure to beta A(25-35).     

Lipid emulsions reduce NMDA-evoked currents

Membrane currents conducted by the NMDA receptor channels were investigated in cultured cortical neurons and TsA cells transfected with NR1-1a/NR2A subunits of the NMDA receptor. The whole-cell recording technique was used. Current transients evoked by bath application of NMDA for 5 s were characterized by a fast peak and a slow decay to 46.1 +/-15.5% of the peak level at the end. When NMDA was applied in combination with various lipid emulsions (Intralipid, ClinOleic, Lipofundin or Abbolipid, the NMDA-induced currents were reduced, although this reduction did not affect the fast peak, it did affect the decay phase. The amount of reduction depended on the concentration of the lipids (in the case of Abbolipid diluted at 1:40, the current at the end of the 5-s drug application was approximately 2/3 of control). When Abbolipid was applied 40 s before NMDA, peak and late current were reduced to approximately 2/3. The effect of current reduction was the same at either of the two chosen membrane potentials (-80 and +40 mV) which indicates that the effect was not mediated by contamination of the emulsions with Mg(2+). The current reduction produced by Abbolipid was about the same in native neuronal cells and in TsA cells expressing the NR1-1a/NR2A subunits. The current-reducing effect of the lipid emulsions may add to the anesthetic, analgesic and neuroprotective effects seen with hypnotics administered by way of lipid carriers.     

Ultrastructural identification of protein bodies, cellular markers of human catecholamine neurons, in a temporal lobe ganglioglioma

A temporal lobe ganglioglioma, surgically removed from an 8-year-old body, and a human brainstem at the level of locus coeruleus (LC) were processed for light microscopy (LM), with formalin fixation and paraffin embedding, and for electron microscopy (EM) with glutaraldehyde fixation, potassium permanganate postfixation, phosphotungstic acid-hematoxylin block-staining, and epoxy-resin embedding. The paraffin sections were stained with toluidine blue O/rhodamine B and observed under epi-fluorescence. The thin sections for EM were viewed directly without further staining. The neuronal neoplastic cells of ganglioglioma and the neurons of LC are known to produce catecholamines. Both also contain spherical protein bodies (pb), cellular markers that identify catecholamine neurons in humans. The ultrastructural characteristics of the pb in LC were compared with those of the pb in neoplastic ganglion cells. These bodies had an identical ultrastructure, in both tissues, consisting of electron-lucent core surrounded by an electron-dense thin rim. The rhodamine B-stained sections also emphasized the identical morphology of the pb in ganglioglioma and LC. Based on the EM comparison, these brightly fluorescing spherical bodies are ideal markers for identifying in LM, the clusters of large neoplastic cells, representing neurons, which are the most important clue to the correct diagnosis of gangliogliomas.     

热休克对氧化应激神经元产生NO的影响

目的 揭示脑在氧化应激状态下一氧化氮产生增多你神经细胞的毒性作用和热休克减少ＮＯ的产生对神经的保护作用机制。方法 对培养大鼠脑皮质神经元分别进行缺氧,Ｈ２Ｏ２,热休克＋缺氧和热休克＋Ｈ２Ｏ２处理,检测丙二醛,超氧化物歧化酶（ＳＯＤ）,ＮＯ和乳酸脱氢酶,并分析它们的变化和相互关系。     

银杏内酯B抗缺血神经元凋亡的预适应作用

目的研究银杏内酯B(Ginkgolide B,GB)对缺血引起的神经元凋亡的影响,并从预适应角度探讨其可能的机制。方法原代培养的小鼠皮层神经元,经过短时缺血预适应(1%O2,无糖DMEM)或GB预处理(120μmol/L,24h)后,再进行严重缺血损伤,通过MTT比色法观察细胞的活性,Hoechst 33342荧光染色检测细胞的凋亡;Western-blot分析磷酸化糖原合成酶激酶-3β(phosphorylated glycogen synthase kinase-3β,p-GSK-3β)和活化的Caspase-3蛋白表达量的变化。结果神经元缺血后活性下降,凋亡比率增高;缺血预适应或银杏内酯B预处理可提高缺血神经元p-GSK-3β的表达,抑制Caspase-3的活化,提高缺血神经元的活性,降低凋亡比率。结论银杏内酯B对缺血诱导的神经元凋亡具有拮抗作用,其作用机制与缺血预适应相似,两者均能提高p-GSK-3β的表达,抑制Caspase-3的活化,银杏内酯B对神经元可发挥药理性预适应作用。     

单纯疱疹病毒1型感染对原代培养鼠皮质神经元凋亡caspase-3途径的影响

目的 了解caspases-3在单纯疱疹病毒1型（herpes simplex virus type1,HSV-1)感染原代培养鼠皮质神经元中对线粒体的调控作用以及与神经元凋亡的关系。方法 用酶标仪检测体外培养小鼠皮质细胞正常组、病毒组、山梨醇加病毒组、对照组在不同条件下caspase-3发光底物吸收值，测定caspase-3底物的含量。用流式细胞术结合TUNEL方法检测各组细胞凋亡情况及线粒体膜电位变化。结果 加入底物后14h测定A值：正常组为0.3942、病毒1组为0.2408、山梨醇组为0.5392、病毒加山梨醇组为0.4650，正常组caspase-3含量较阴性对照组增加，病毒组较正常组明显减低，山梨醇组较正常组明显增加，病毒组较正常组明显减低，山梨醇组较正常组明显增加，病毒加山梨醇组较山梨醇组减低。山梨醇及神经酰胺组细胞线粒体膜电位明显降低，而病毒组及病毒加山梨醇或神经酰胺组均无明显降低。结论 正常体外培养的神经元存在细胞凋亡，病毒能够阻止线粒体膜电位的超极化，山梨醇诱导的神经细胞凋亡是依赖于caspase-3的细胞凋亡，HSV-1阻止依赖于caspase-3的细胞凋亡途径。     

关于肽类生长因子对神经发育作用及其机制的认识

肽类生长因子对神经系统发育发挥着重要的调控作用，与神经退行性疾病的发生和发展也密切相关，在研究过程中要运用哲学原理作指导，充分认识肽类生长因子结构和功能的多样性、其受体及其作用机制的复杂性，处理好基础研究与实践的辨证关系，从单纯分析研究走向系统研究。