Neuronal and glial differentiation within expanded glial cultures derived from the lateral and medial ganglionic eminences

Attached glial-like cell cultures were established from the lateral and medial ganglionic eminences (LGE and MGE) and from the neocortex (Cx) of E13.5 mouse embryos, and expanded over four to five passages under epidermal growth factor (EGF) stimulation. Following removal of EGF and serum, we analysed the generation of neurons and glial cells within the cultures. Significant numbers of betaIII-tubulin-positive neurons were generated in both the LGE (about 7% of total cell numbers) and the MGE (around 2%). However, only few betaIII-tubulin-positive cells with neuronal morphologies were detected in the differentiated Cx cultures. The newly formed neurons were to a large extent GABAergic, and many of the MGE-derived, but not the LGE-derived, cells expressed the MGE-marker NKX2.1. Most cells in all cultures still appeared astroglial-like, expressing glial fibrillary acidic protein (GFAP), but in addition, CNPase-positive cells with oligodendroglial morphologies were present in the MGE (0.68%), and, to a lesser extent (0.2%), in the LGE cultures. The present results demonstrate that cells of expanded glial cultures from both the LGE and MGE can give rise to significant and, to a certain extent, region-specific neuronal and glial cell types under differentiating conditions.     

Endothelin B receptor deficiency augments neuronal damage upon exposure to hypoxia-ischemia in vivo

The role of functional endothelin-B (ETB)-receptors on neuronal survival upon hypoxia-ischemia (HI) has been investigated in 14-day-old ETB-receptor-deficient spotting lethal (sl/sl) and wildtype (+/+) rats. Carotid ligation followed by exposure to 8% oxygen for 2 h produced distinct cortical and hippocampal neuronal damage. Damage severity 24 h after HI was mild to intermediate in +/+ rats whereas large cortical infarcts and profound apoptosis of the hippocampus evolved in sl/sl rats. The number of apoptotic cells in the dentate 24 h after HI amounted to 30 +/- 7 cells/0.1 mm(2) in sl/sl compared to 9 +/- 3 cells/0.1 mm(2) in wildtype rats (mean +/- S.E.M., n=10-11, P=0.0093). In-vitro hypoxia (15 h) resulted in a comparable increase in cell death in primary pure neuronal hippocampal cultures from both groups (49.8 +/- 1.6% in sl/sl, 51.4 +/- 0.9% in +/+, mean +/- S.E.M., n=5, P=0.0560). To conclude, absence of functional ETB receptors is associated with an increased susceptibility to HI in-vivo, which is not intrinsic to neurons. Antagonism of ETB receptors seems not to be desirable in ischemic stroke.     

星形胶质细胞低氧预适应对缺氧神经元的保护作用

目的：观察星形胶质细胞低氧预适应对神经元缺氧损伤的影响及机制。方法：收集低氧预适应后星形胶质细胞条件培养液（ACM）用于神经元培养。用MTT比色法检测细胞活性，Western Blot法分析星形胶质细胞促红细胞生成素的表达。结果：星形胶质细胞缺氧0．5h和3h后，活性升高，促红细胞生成素表达增多；神经元缺氧后活性明显降低，但低氧处理的ACM可阻止此变化的发生。结论：低氧预适应的ACM对神经元缺氧具有明显的保护作用，其机制可能是星形细胞表达促红细胞生成素增多，通过培养液作用于神经元，从而抑制神经元缺氧后活性的降低。     

Aβ_(1-40)诱导皮层神经元凋亡和人参二醇的保护作用

目的:研究β-淀粉样肽(Aβ1-40)对原代培养的小鼠大脑皮层神经细胞凋亡的诱导和人参二醇(panoxadiol)的保护作用. 方法:通过形态学观察,MTT法检测,DNA琼脂糖凝胶电泳,Western-blot等方法研 究Aβ1-40对皮层神经元的损伤及人参二醇(由浙江省中医院提供)的保护作用.结果:原代培养的小鼠大脑神经细胞经12 μmol/L Aβ1-40作用48 h后 ,Aβ1-40损伤组神经细胞出现明显的凋亡特征,OD值降低,DNA电泳出现DNA片段, 凋亡细胞数目增多.Western-blot显示Aβ1-40损伤组bcl-2表达下降(P<0. 05),而40 mg/L人参二醇预处理24 h后可明显改变上述凋亡特征.结论:4 0 mg/L人参二醇可减缓12 μmol/L Aβ1-40诱导培养皮层神经元凋亡,对凋亡细胞 有一定的保护作用.     

海马神经元癫痫样放电后ERK1/2信号通路与c-fos的相关性

目的 研究海马神经元癫痫样放电后细胞外信号调节激酶(ERK1/2)与c-fos之间的相关性.方法 用无镁细胞外液建立海马神经元癫痫样放电模型,分为模型组、抑制剂组(加入10μmol/L U0126)和对照组(不作任何处理,只取0 min).运用免疫荧光双标标记,在激光共聚焦扫描显微镜下观察建模后30 min,磷酸化ERK1/2(p-ERK1/2)和c-fos在神经元内的分布;采用Western印迹检测p-ERK1/2和c-fos在相应处理后0、30 min,2、6、12和24 h的表达.结果 免疫荧光双标显示:癫痫样放电后30 min p-ERK1/2在神经元胞核与胞质内都有表达,而c-fos只在核内表达.Western印迹表明:模型组中各时间点p-ERK1/2都有表达,c-fos与P-ERK1/2变化趋势相似,30 min达峰值(1.849±0.059).抑制剂组中,P-ERK1/2表达完全被抑制,c-fos表达明显减少,且各时间点表达强度相近(30min时0.127±0.029),模型组与抑制剂组及对照组(0.241±0.030)在相应时间点之间比较差异有统计学意义(均P＜0.01).结论 海马神经元癫痫样放电后ERK1/2信号通路被持久激活,阻滞ERK1/2磷酸化,可以下调c-fos基因的表达.     

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.