右美沙芬对培养大鼠皮层神经元谷氨酸兴奋毒性和缺氧损伤的保护作用

本文采用16～18d胎龄的大鼠皮层细胞进行分离培养，以培养上清液中乳酸脱氢酶（LDH）活性作为细胞损伤的指标，分别观察了缺氧和过量谷氨酸对皮层神经元的影响以及右美沙芬的保护作用。实验结果表明，外源性谷氨酸（10和50μmol／L）和缺氧（5h）均引起LDH释放增加，而这种作用皆被右美沙芬所抑制。提示右美沙芬对此有明显的保护作用。以上结果说明谷氨酸兴奋毒性与NMDA受体在缺血性脑损伤过程中起着重要的作用。     

自噬抑制剂3-MA抑制EV71病毒颗粒的产生与释放

目的 通过研究肠道病毒71型（Enterovirus 71,EV71）感染引起细胞的自噬及抑制自噬对病毒滴度的影响,为进一步明确EV71的致病机制提供基础.方法 利用Western Blot检测EV71感染后RD-A细胞内源性LC3的型别转换和P62的降解来指示细胞发生自噬的水平,通过测定染毒细胞培养上清中EV71病毒CCID50来观察抑制自噬后细胞释放EV71感染性病毒颗粒的变化.结果 EV71的感染促进了细胞LC3的型别转换和F62的降解,诱导了细胞发生自噬;3-MA抑制细胞自噬后,EV71染毒细胞产生的感染性EV71病毒颗粒数量减少.结论 EV71可以诱导细胞发生自噬,细胞自噬可能促进EV71感染性病毒颗粒的产生和释放.     

自噬抑制剂3-MA抑制EV71病毒颗粒的产生与释放

目的 通过研究肠道病毒71型(Enterovirus 71,EV71)感染引起细胞的自噬及抑制自噬对病毒滴度的影响,为进一步明确EV71的致病机制提供基础.方法 利用Western Blot检测EV71感染后RD-A细胞内源性LC3的型别转换和P62的降解来指示细胞发生自噬的水平,通过测定染毒细胞培养上清中EV71病毒CCID50来观察抑制自噬后细胞释放EV71感染性病毒颗粒的变化.结果 EV71的感染促进了细胞LC3的型别转换和F62的降解,诱导了细胞发生自噬;3-MA抑制细胞自噬后,EV71染毒细胞产生的感染性EV71病毒颗粒数量减少.结论 EV71可以诱导细胞发生自噬,细胞自噬可能促进EV71感染性病毒颗粒的产生和释放.

Abstract：

Objective To determine whether or not enterovirus 71 ( enteroviurs 71, EV71) may induce autophagy and affect the production and release of EV71 after the treatment of autophagy inhibitor. Methods Western blots were performed to examine the conversion of LC3- Ⅰ to LC3-Ⅱ and the degradation of P62 after the RD-A cells were infected with EV71. CCID50 was determined by checking the virus titer in the supernatant of cells that treated with autophagy inhibitor 3-MA. Results EV71 infection enhances the type conversion of LC3 and degradation of P62. The infectious virus particles were decreased after the treatment of 3-MA. Conclusion EV71 infection could induce cell autophagy and the autophagy might contribute to the production and release of infectious EV71 particles.     

细胞自噬缓解氧-糖剥夺诱导原代培养小鼠脑皮质神经元缺血损伤

目的 在离体细胞水平,探讨氧-糖剥夺(OGD)致原代培养小鼠脑皮质神经元缺血损伤过程中,细胞自噬的变化情况和可能作用.方法 出生24h内C57BL/6J乳鼠脑皮质神经元原代培养7d后,分为常氧(Nor.)、15、30、60、90和120 min OGD后24h复糖复氧等6组,每组n=6;免疫印迹(Western blot)法检测细胞自噬相关蛋白Beclin-1表达和LC3Ⅱ/Ⅰ比值;借助MTT比色法和乳酸脱氢酶(LDH)漏出率,检测神经元的损伤;用细胞自噬下游抑制剂巴弗洛霉素A1(BafA1 100 nmol/L)抑制自噬后,观察神经元的损伤.结果 与对照组相比,随OGD时间的延长,自噬相关蛋白Beclin-1表达水平和LC3Ⅱ/Ⅰ比值显著升高,30 min达到峰值,之后略有回降(P＜0.05);在OGD处理30和60 min致使神经元显著损伤的基础上,细胞自噬抑制剂BafA1可明显加重60 min OGD处理神经元的损伤和提高LC3Ⅱ/Ⅰ的比值(P＜0.05).结论 OGD可诱发原代培养小鼠脑皮质神经元自噬发生,且细胞自噬可缓解OGD处理皮质神经元的缺血损伤.     

自噬抑制剂3-甲基腺嘌呤对肝星状细胞增殖活化的影响

目的 观察自噬抑制剂3-甲基腺嘌呤(3-MA)对大鼠肝星状细胞(HSC-T6)增殖活化的影响,并探讨其作用机制.方法 体外培养大鼠肝星状细胞株HSC-T6,设立空白对照组和3-MA低剂量组(2.5 mmol/L)、中剂量组(5 mmol/L)、高剂量组(10 mmol/L).RT-PCR分析不同浓度3-MA对HSC活化标志蛋白α-平滑肌肌动蛋白(α-SMA)以及Ⅰ型胶原蛋白基因表达的影响,Western blot法检测不同浓度3-MA对HSC中自噬水平标志蛋白LC3Ⅱ、α-SMA以及Ⅰ型胶原蛋白表达水平的影响;MTT法检测3-MA对HSC增殖的影响,流式细胞术分析3-MA对HSC细胞周期的影响.结果 低、中、高剂量3-MA作用于HSC后,HSC-T6细胞自噬水平随3-MA浓度升高逐渐下降,α-SMA、Ⅰ型胶原蛋白mRNA相对表达量均明显低于对照组(P＜0.05),LC3Ⅱ、α-SMA以及Ⅰ型胶原蛋白相对表达量均明显低于对照组(P＜0.05).与对照组相比,低、中、高剂量时3-MA对HSC增殖的影响均显著下降(P＜0.05),G2期比例与对照组比较均明显增加(P＜0.05).结论 3-MA可下调大鼠HSC-T6细胞LC3Ⅱ的表达,抑制α-SMA及Ⅰ型胶原蛋白mRNA及蛋白的表达,使HSC-T6细胞周期停滞于G2期,抑制HSC增殖活化.     

D-半乳糖致原代培养神经元损伤模型的研究

目的:建立D-半乳糖致原代培养神经元损伤模型,为筛选益智药物提供药效学研究方法。方法:在原代培养神经元的第6d,加入50mmol/LD-半乳糖作用72h,倒置显微镜下观察神经元的生长发育形态,MTT法在酶联免疫检测仪上检测神经元代谢率,PI染色在流式细胞仪上检测神经元凋亡率,HE染色观察神经元形态、形态计量神经突起密度,RT-PCR检测醛糖还原酶信使RNA(AR-mRNA)含量。比较正常对照神经元和受D-gal攻击神经元之间的差别。结果:受D-半乳糖攻击神经元的生长发育显著迟缓;代谢率从0.762±0.030(n=33)降低到0.543±0.064(n=11),P<0.01;凋亡率从0.060±0.029(n=19)增高到0.356±0.215(n=19),P<0.01;出现变性坏死的形态变化,神经突起密度从0.557±0.042(n=10)降低到0.468±0.033(n=10),P<0.01;无AR-mRNA的表达。结论:用D-半乳糖建立的原代培养神经元损伤模型稳定、观察指标敏感,可用于老年性痴呆等神经系统疾病的研究。     

自噬与心肌缺血/再灌注损伤

Autophagy is a lysosome-dependent degradative pathway which is characterized by cytoplasmic vacuolization. However, it is not just a simple degradative pathway. Research shows that autophagy is related to many diseases, such as neurodegenerative disease, malignant tumor, ageing, pathogenic microorganism infection, myocardial ischemia/reperfusion injury and so on. Autophagy exactly exists in myocardial ischemia/reperfusion injury, and it becomes a new research hotspot. This review will focus on the occurrence and development of autophagy and its role, signal transduction and research status in myocardial ischemia/reperfusion injury.     

细胞自噬水平在大鼠缺血/再灌注肺组织内变化及其作用

目的 探讨大鼠肺缺血再灌注后肺组织内自噬水平的变化和自噬在肺缺血再灌注损伤中的作用.方法 大鼠分为假手术组和缺血1 h再灌注0、2、6 和24 h组,免疫印迹法检测自噬标志蛋白LC3-Ⅱ的表达,电子显微镜观察细胞内自噬体.自噬抑制剂3-甲基腺嘌呤(3-MA)和安慰剂分别预处理假手术组和缺血再灌注2 h组大鼠,HE染色和血气分析检测肺组织损伤程度.结果 LC3-Ⅱ/Actin比值在缺血1h时即有升高,再灌注2～6h达高峰(P＜0.01),再灌注24 h恢复至接近假手术组水平.主要在Ⅰ型肺泡上皮细胞和血管内皮细胞内观察到自噬体.3-MA预处理降低肺组织损伤评分,升高血氧分压,减轻肺缺血再灌注损伤(P＜0.05).结果证实,肺缺血及再灌注诱发肺组织呼吸膜细胞自噬激活,3-MA预处理通过抑制自噬改善肺缺血再灌注损伤.结论 细胞自噬可能是肺缺血再灌注病理生理过程中加重损伤的因素.     

谷氨酸诱导大鼠胃Cajal间质细胞自噬模型的建立

目的:通过谷氨酸诱导离体大鼠胃Cajal间质细胞(ICCs)建立细胞自噬模型。方法:使用高、中和低浓度(分别为10 mmol/L、5 mmol/L和2.5 mmol/L)的谷氨酸作用于原代培养的ICCs不同时间(3h、6h和24h),然后通过CCK-8法检测不同浓度谷氨酸对ICCs活力的影响;Western blot检测不同浓度谷氨酸在不同作用时点对ICCs自噬蛋白微管相关蛋白1轻链3(LC3)表达水平的影响;透射电镜观察谷氨酸干预后细胞内自噬体和超微结构的变化;免疫荧光检测谷氨酸诱导后自噬蛋白LC3的荧光表达。结果:与空白对照组相比,谷氨酸显著降低了大鼠胃ICCs活力(P0.01)。中、高浓度谷氨酸作用不同时间均可显著提高自噬蛋白LC3-II/LC3-I的比值(P0.01),其中以中浓度谷氨酸作用3 h的LC3-II/LC3-I比值最高(P0.01)。透射电镜检测中浓度谷氨酸干预3 h发现,细胞内自噬体数量明显增加,线粒体和内质网数量及结构遭到破坏。免疫荧光结果提示,与空白对照组比较,谷氨酸中浓度组平均每个细胞内自噬蛋白LC3荧光表达显著增强(P0.01)。结论:应用谷氨酸可成功诱导大鼠胃ICCs自噬,谷氨酸的最佳诱导条件为5 mmol/L作用3h。     

NS398对Aβ肽损伤原代培养海马神经元的影响

目的:探讨Cox-2抑制剂NS398对损伤神经元的保护作用。方法:将原代培养的SD大鼠海马神经元随机分为空白对照组、Aβ肽细胞模型组和NS398实验组。以10μmol/L Aβ25-35制作原代培养海马神经元损伤模型,以四氮唑溴盐(MTT)比色法检测细胞存活率,免疫细胞化学法检测Cox-2、Caspase-3的表达。结果:Aβ25-35细胞模型组神经元形态变化明显,细胞存活率明显下降,Cox-2和Caspase-3表达增强,与空白组比较有显著差异(P<0.01)。NS398使神经元细胞存活率明显提高并使Cox-2和Caspase-3表达减弱,与Aβ肽模型组比较具有显著性差异(P<0.01)。结论:Aβ25-35导致Cox-2和Caspase-3的表达增强,并使SD大鼠原代培养海马神经元变性、死亡。NS398可能通过抑制Cox-2和Caspase-3的表达保护原代培养海马神经元。     

谷氨酸诱导海马神经元凋亡涉及线粒体释放细胞色素C

目的：建立体外谷氨酸诱导神经元兴奋损伤模型，探索其凋亡发生是否通过线粒体信号转导途径介导的细胞色素C（Cyt C）释放而实现，为今后干预性使用神经保护剂提供依据。方法:分离及培养新生Wistar大鼠海马神经元，选用合适谷氨酸浓度建立神经元损伤模型；利用LDH测定及流式细胞仪Annexin V/PI双染色法检测谷氨酸暴露后不同时点神经元凋亡及坏死的动态改变；采用Western blotting法检测caspase-3活性及线粒体内和胞浆内Cyt C水平动态变化。结果:谷氨酸诱导神经元损伤呈明显浓度及时间依赖性，50 μmol/L浓度可使LDH释放量明显增加 (18.4%,P<0.05)，暴露后6 h凋亡率显著增加；凋亡发生前，神经元caspase-3活性已明显增高（3 h），6 h达高峰；线粒体Cyt C释放发生在caspase-3增高前，30 min时胞浆内Cyt C水平即明显增加（P<0.05），3 h胞浆内Cyt C水平超过线粒体内，而线粒体内Cyt C水平进行性减少。结论:50 μmol/L谷氨酸可诱导海马神经元凋亡，凋亡机制可能是通过损伤线粒体膜，使Cyt C易位释放入胞浆激活caspase级联反应而致。     

Transient increase in glutamic acid decarboxylase mRNA in the cerebral cortex following focal cortical lesion in the rat

Summary In situ hybridization histochemistry (ISHH) was used to study the expression of glutamic acid decarboxylase (GAD) mRNA changes in the rat cerebral cortex following unilateral frontal and somatosensory cortical lesion by devascularisation. 4 days after the lesion, a significant transient increase in GAD mRNA level in the ipsilateral cortex was observed when compared with contralateral, ipsi-sham operated and ipsi-normal control cortices. The change occurred throughout the ipsilateral neocortex, with no significant difference between the magnitude of increase in frontal, parieto-occipital, parieto-temporal, cingulate or retrosplenial areas; no obvious change was seen in pyriform, entorhinal or hippocampal cortices. This unexpected GAD mRNA increase in neocortex may be part of a long term adaptive functional alteration and changes in the gene expression of the cerebral cortex following focal cortical injury.A preliminary report of these findings was presented at the annual general meeting of the Anatomical Society of Great Britain and Ireland     

Excitation and depression of cortical neurones during spreading depression

Summary Variations in the excitability of individual cortical neurones during the invasion of spreading depression (SD) have been monitored by observing the alterations of spontaneous and L-glutamate-induced firing. Invasion of many neurones during SD is marked by a brief burst of firing which occurs concurrently with the onset of the negative slow extracellular potential. Other neurones do not fire, although the microelectrode records a negative slow wave. Depression of glutamate-induced and spontaneous firing follows and may last for several minutes. The initial loss of excitability of those neurones that discharge during SD invasion may be due to excessive depolarization. This phase is rapidly succeeded by a period of depressed excitability, during which the neurones can be invaded by an antidromic spike or excited by increased amounts of L-glutamate. These findings indicate that SD propagation initially involves the release of an excitant substance, possibly glutamic acid. The continuing effects of SD are due to the reduction in cell excitability. As many neurones are depressed without undergoing an initial excitation, it appears that a depressant substance is also involved. This may be gamma-aminobutyric acid.     

银杏内酯B对谷氨酸诱导脑皮质神经元凋亡及Ca2+超载的影响

目的：观察银杏内酯B对谷氨酸诱导培养脑皮质神经元凋亡的拮抗作用，并探讨这种作用与神经细胞内游离Ca2+浓度改变的关系。方法： 采用改良的方法原代培养胎小鼠脑皮质神经元，用噻唑兰（MTT）法检测神经元的存活情况；细胞凋亡采用形态学观察、DNA琼脂糖凝胶电泳法和Hoechst 33258核染色方法进行分析；用Fura-2/AM荧光指示剂法测定细胞内Ca2+浓度。结果： 谷氨酸（0.8 mmol/L）能诱导神经细胞凋亡和胞内Ca2+超载，银杏内酯B（10-250 μmol/L）能减轻谷氨酸所致的细胞损伤，表现为神经元存活率提高，细胞形态的恢复和DNA断裂减少。结论： 银杏内酯B可拮抗谷氨酸所致的神经细胞毒性作用，这可能与其能竞争PAF受体并降低神经细胞内［Ca2+］从而抑制谷氨酸诱导的神经元凋亡有关。     

ATP is released from nerve terminals and from activated muscle fibres on stimulation of the rat phrenic nerve

Immunohistochemical experiments were performed using glutamic acid decarboxylase (GAD) to identify γ-aminobutyric acid (GABA)ergic neurons in the vestibular nuclei (VN). VN neurons projecting to the sensory trigeminal complex (STC) or to the C1–C2 segments of the spinal cord were identified by injection of wheat germ agglutinin-apo-horseradish peroxidase coupled to colloidal gold (gold-HRP), a retrogradely transported tracer, in these structures. The experiments combining injection of gold-HRP in spinal cord and GAD immunohistochemistry revealed the existence in the medial, inferior and lateral VN of GAD immunoreactive neurons projecting to the spinal C1–C2 level. Experiments combining injection of gold-HRP in the STC and GAD immunohistochemistry demonstrated that, at least, 30–50% of the vestibulo-trigeminal neurons also contained GAD. Injections of two different retrograde tracers (gold-HRP and Biotinylated dextran amine) in the STC and the spinal cord demonstrated that some VN neurons project by axon collaterals to both structures. Because of the GABAergic spinal and STC vestibular projections we assume that these VN neurons with collateral projection are GABAergic. Therefore primary afferents from the face, neck or hindlimb could be modulated by inhibitory influences from GABAergic vestibular neurons.     

Modulatory role of glutamic acid on the electrical activities of pain-related neurons in the hippocampal CA3 region

Glutamic acid (Glu) participates in pain modulation of the central nervous system. The CA3 region of the hippocampal formation has been suggested to be involved in nociceptive perception. However, it is unknown whether Glu could modulate the electrical activities of pain-related neurons in the hippocampal CA3 region. The present study aimed to determine the effects of Glu and its receptor antagonist MK-801 in the pain-evoked response of both pain-excited neurons (PENs) and pain-inhibited neurons (PINs) in the hippocampal CA3 region of normal rats. We used a train of electric impulses applied to the sciatic nerve as noxious stimulation. The electrical activities of either PENs or PINs in the hippocampal CA3 region were recorded by a glass microelectrode. The results revealed that intra-CA3 region microinjection of Glu (0.5 μg/1 μl) increased the evoked firing frequency and shortened the firing latency of PEN, while decreased the evoked firing frequency and prolonged the inhibitory duration of PIN in the hippocampal CA3 region of rat evoked by the noxious stimulation. Intra-CA3 region administration of MK-801 (0.25 μg/1 μl) produced the opposite response. These results suggest that Glu and its receptors in hippocampal CA3 region are involved in the modulation of nociceptive information transmission by affecting the electric activities of PENs and PINs.     

A subset of cingulate cortical neurones is specifically activated during alcohol‐acquisition behaviour

A new need is associated with the formation of behaviour directed at its satisfaction. In chronically ethanol‐treated rabbits a bodily need develops to acquire and consume alcohol. The present study examined the firing properties of single neurones in the cingulate (limbic) cortex of chronically ethanol‐treated rabbits. The main questions of this study were: are there neurones in the cingulate cortex which specifically increase their firing during alcohol‐acquisition behaviour (AAB)? What is the relationship between the neuronal mechanisms of pre‐existing and newly formed behaviour? Adult rabbits were taught to acquire food by pressing pedals. After 9 months of ethanol treatment, the same rabbits were taught to acquire ethanol (15% solution in a 0.5‐mL capsule) by means of the same instrumental method. Activity of the 118 neurones was recorded from the cingulate cortex. The comparison of activity of each neurone in AAB and food‐acquisition behaviour (FAB) enabled us to reveal that their subservings overleap substantially but not completely: 41% of ‘common neurones’ involved in the subserving of both FAB and AAB as well as 5% of ‘alcohol‐neurones’ (alcohol‐acquisition specific cells) were found. We think of the latter neurones as units that were specialized during the forming of alcohol‐seeking behaviour. Thus, present experiments help us not only to answer the above questions but also to provide an additional insight into the nature of similarity between neuronal mechanisms of long‐term memory and long‐lived modifications resulting from repeated drug exposure.     

Proteolytic activity during cortical development is distinct from that involved in hypoxic ischemic injury

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases involved in brain development and the etiology of adult cerebral injuries. In this study, we determined the MMP-2 and 9 responses following hypoxic ischemia (HI) injury in the developing brain. First, we characterized the developmental changes of MMP activity in the rat brain from embryonic day 18 (E18) to postnatal day 120 (P120). MMP-2 activity was high from E18 to P3 and decreased with age (P< or =0.001), while MMP-9 activity was not detectable. MMP-2 immunoreactivity was closely associated with differentiating cortical plate and subplate neurons. Next, we characterized the proteolytic changes after unilateral HI brain injury in 3- (P3) and 21- (P21) day-old rats. Zymography revealed that in the P21 rat brain, MMP-9 activity (150 and 92 kDa forms) was increased at 6 h and remained elevated 24 h post-injury in the ipsilateral injured hemisphere (P< or =0.001), whereas there was a gradual increase in MMP-2 (65 kDa) activity, reaching a peak at 5 days (P< or =0.001). Similarly, quantitative real time polymerase chain reaction (qRT-PCR) indicated significant elevations in MMP-9 and MMP-2 mRNA expression in the injured cortex (P< or =0.05) and hippocampus (P< or =0.05) at 1 and 5 days post-injury, respectively in the P21 rat brain. In the P3 rat brain, zymography results revealed that both pro (92 kDa) and cleaved (87 kDa) MMP-9 activities were upregulated in the ipsilateral injured hemisphere from 6 h to 1 day after injury (P< or =0.001). In contrast, cleaved MMP-2 (60 kDa) was only moderately upregulated at 6 h (P< or =0.01), while pro MMP-2 (65 kDa) levels were unaffected. MMP-9 mRNA expression was also increased at 6 h (P< or =0.05) following injury at P3, whereas MMP-2 expression remained unchanged compared with the uninjured contralateral hemisphere. Immunohistochemistry indicated that MMP-9 protein expression was localized predominantly to neurons and peri-vascular astrocytes in the affected regions at early time points, whereas MMP-2 was present on reactive astrocytes surrounding the infarct at later time points. Together, these results indicate that MMP-2 may be primarily associated with the development and differentiation of cortical plate neurons and wound recovery processes. Conversely, MMP-9 appeared to be associated with more acute processes during the period of lesion development.     

Pigment epithelium-derived factor (PEDF) protects cortical neurons in vitro from oxidant injury by activation of extracellular signal-regulated kinase (ERK) 1/2 and induction of Bcl-2

Mitigating oxidative stress-induced damage is critical to preserve neuronal function in diseased or injured brains. This study explores the mechanisms contributing to the neuroprotective effects of pigment epithelium-derived factor (PEDF) in cortical neurons. Cultured primary neurons are exposed to PEDF and H₂O₂ as well as inhibitors of phosphoinositide-3 kinase (PI3K) or extracellular signal-regulated kinase 1/2 (ERK1/2). Neuronal survival, cell death and levels of caspase 3, PEDF, phosphorylated ERK1/2, and Bcl-2 are measured. The data show cortical cultures release PEDF and that H₂O₂ treatment causes cell death, increases activated caspase 3 levels and decreases release of PEDF. Exogenous PEDF induces a dose-dependent increase in Bcl-2 expression and neuronal survival. Blocking Bcl-2 expression by siRNA reduced PEDF-induced increases in neuronal survival. Treating cortical cultures with PEDF 24 h before H₂O₂ exposure mitigates oxidant-induced decreases in neuronal survival, Bcl-2 expression, and phosphorylation of ERK1/2 and also reduces elevated caspase 3 level and activity. PEDF pretreatment effect on survival is blocked by inhibiting ERK or PI3K. However, only inhibition of ERK reduced the ability of PEDF to protect neurons from H₂O₂-induced Bcl-2 decrease and neuronal death. These data demonstrate PEDF-mediated neuroprotection against oxidant injury is largely mediated via ERK1/2 and Bcl-2 and suggest the utility of PEDF in preserving the viability of oxidatively challenged neurons.