羟基红花黄色素Ａ抗谷氨酸氧化性神经损伤的保护作用

目的研究羟基红花黄色素A(HSYA)对谷氨酸(Glu)诱导的氧化性神经损伤的保护作用。方法以体外原代培养Wistar胎鼠大脑皮层神经元为实验材料，进行形态学观察，采用噻唑蓝（MTT）比色法、Hoechst33342/PI双荧光探针染色、超氧化物歧化酶（SOD）和谷胱甘肽（GSH）含量检测、流式细胞仪分析细胞凋亡率以及免疫细胞化学法检测细胞色素C（CytC）荧光强度，综合评价HSYA对Glu氧化性神经损伤的保护作用。结果与Glu损伤组相比，HSYA能显著提高细胞相对存活率，维持细胞内较高SOD和GSH水平，降低Glu引起的细胞凋亡率及线粒体内CytC向胞质的释放，以160μg/mL浓度的 HSYA保护效果最为显著。结论HSYA对Glu氧化性神经损伤有显著的保护作用，其机制与抗氧化、抑制细胞凋亡有关。     

辣椒素对背根神经节神经元钙离子浓度和线粒体膜电位的影响

目的探讨辣椒素对体外原代培养的胎鼠背根神经节（dorsal root ganglion，DRG）神经元钙离子浓度（［Ca²⁺］_i）和线粒体膜电位（mitochondiral membrane potential，MMP）的影响作用。方法分散培养的胎鼠DRG神经元用不同浓度的辣椒素（0.001μmol/L, 0.01μmol/L, 0.1μmol/L, 1μmol/L, 10μmol/L）孵育1min，用共聚焦激光扫描显微镜检测神经元［［Ca²⁺］_i的改变。对于能引起［Ca²⁺］_i升高的浓度组，在辣椒素孵育1min时，用流式细胞术检测神经元MMP的变化；并且在移去辣椒素后10min，重新检测神经元［Ca²⁺］_i的变化。结果0.001μmol/L、0.01μmol/L辣椒素孵育1min，神经元胞内［［Ca²⁺］_i没有变化；0.1μmol/L、1μmol/L和10μmol/L辣椒素孵育1min，神经元胞内［Ca²⁺］_i升高，移去辣椒素后10min，0.1μmol/L、1μmol/L辣椒素孵育的DRG神经元胞内［Ca²⁺］_i恢复到基础水平，10μmol/L辣椒素孵育的标本升高的［Ca²⁺］_i没有明显改变。辣椒素孵育时用无钙溶液，则神经元胞内［Ca²⁺］_i不升高。10?μmol/L辣椒素孵育1min的DRG神经元MMP降低，0.1μmol/L和1μmol/L辣椒素孵育的标本MMP无明显变化。结论一定浓度的辣椒素可使原代培养的DRG神经元胞内［Ca²⁺］_i升高，MMP降低。低浓度辣椒素引起的［Ca²⁺］_i的升高在10min内可以恢复到基础水平，而高浓度辣椒素引起的［Ca²⁺］_i的升高在10min内则不能恢复。辣椒素所致的胞内［Ca²⁺］_i升高可能是由于胞外钙离子内流引起的。     

人参皂苷Rg1对6-OHDA所致MES23.5神经细胞损伤的保护作用

目的 探讨人参皂苷Rg1对6-羟基多巴胺(6-OHDA) 所致MES23.5神经细胞损伤的保护作用.方法 MES23.5细胞常规培养,观察人参皂苷Rg1预处理对6-OHDA毒性作用的影响,MTT法观察细胞存活率,实时荧光半定量反转录聚合酶链反应(real time RT-PCR)观察酪氨酸羟化酶(TH)和Bcl-2基因的表达情况.结果 6-OHDA 可剂量依赖性地损伤MES23.5细胞(F=71.24,P<0.01),人参皂苷Rg1预处理可对抗6-OHDA的毒性作用(F=14.63,P<0.01);6-OHDA可明显降低TH和Bcl-2基因的表达,人参皂苷Rg1预处理可明显逆转上述改变(F=9.80、15.34,P<0.01).结论 人参皂苷Rg1可明显对抗6-OHDA对MES23.5神经细胞的损伤,其作用机制可能与抗凋亡有关.     

Second-order neural responses after contralateral vestibular nerve sectioning

The characteristics of the response to an 8 degrees/sec2 acceleration of 41 neurons in the medial vestibular nucleus of the cat following vestibular nerve sectioning were compared with those of 73 control neurons at the same site. In 14 of the vestibular nerve-sectioned animals the same neuron was recorded before and after sectioning. No difference was found between the resting discharge rates, maximal response rates, and rates of adaptation of the two groups. Following contralateral vestibular nerve sectioning Type II neurons were still plentiful, suggesting many receive ipsilateral labyrinthine innervation.     

Proteomic characterisation of neuronal sphingolipid-cholesterol microdomains: role in plasminogen activation

Sorting of certain membrane proteins requires a mechanism involving rafts, protein-lipid complexes enriched in glycosphingolipids and cholesterol. These microdomains remain at the plasma membrane of different cell types and play a role in signal transduction. Although recent reports have begun to describe molecules associated with rafts, their protein composition remains largely unknown, especially in neuronal cells. To address this question, we have purified detergent-insoluble raft fractions (DRMs) from primary cultures of hippocampal neurons. Bidimensional gel analysis and pharmacological raft lipid manipulation allowed the identification of neuronal raft proteins and their characterisation by MALDI-TOF analysis. Enolases were found among the proteins identified and functional studies demonstrate their participation in plasminogen binding. We also show the specific enrichment in rafts of several other plasminogen binding molecules and the exclusive activation of plasminogen to the protease plasmin in these microdomains. These observations suggest that neuronal rafts may play, in addition to intracellular signaling, a role in extracellular/membrane protein proteolysis.     

PARP cleavage, DNA fragmentation, and pyknosis during excitotoxin-induced neuronal death

Poly(ADP-ribose)polymerase-1 (PARP-1) is a nuclear enzyme activated by DNA breaks and serves a role in DNA repair through the formation of polymers (poly(ADP)ribosylation) at sites of DNA damage. PARP-1 is activated by DNA damage in neurons of the hippocampus and cerebral cortex following excessive exposure to glutamate receptor agonists such as NMDA or kainic acid. In addition, recent studies suggest that degradation of PARP-1 occurs in cells that undergo apoptotic versus nonapoptotic forms of cell death. To investigate this process further, we examined the spatiotemporal aspects of excitotoxic injury in the rodent visual cortex by making focal intracerebral injections of kainic acid. These injections resulted in DNA damage, PARP-1 activation, and neuronal cell death over a 5-day period. Rapid neuronal cell injury assessed by Fluoro-Jade staining appeared within hours, but increased TUNEL staining occurred only after 24 h. A dramatic increase in caspase-3 activity, as well as an increase in the number of neurons containing active caspase-3, peaked 2 days after injury. Last, increased PARP-1 immunoreactivity and PARP-1 cleavage reached peak levels 2 to 3 days after delivering the excitotoxin. These findings suggest that increased caspase-3 activity may regulate the degradation of PARP-1 in subsets of cortical neurons during excitotoxic cell death.     

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.