TAAR1-EAAT2通路抑制乳鼠星形胶质细胞的谷氨酸摄取能力北大核心CSCD

目的研究多巴胺(DA)对原代星形胶质细胞谷氨酸(Glu)摄取能力的影响,以及DA通过痕量胺相关受体1-兴奋性氨基酸转运体2(TAAR1-EAAT2)信号通路对星形胶质细胞Glu摄取能力的影响。方法采用Amplex Red谷氨酸测定试剂盒测定经过DA处理的原代星形胶质细胞对Glu摄取含量的变化,反转录PCR检测TAAR1、EAAT2 mRNA水平,Western blot法检测TAAR1、EAAT2蛋白水平;采用TAAR1小干扰RNA(siRNA)和TAAR1质粒转染DA处理后的原代星形胶质细胞,Western blot法检测EAAT2表达水平并采用Amplex Red谷氨酸测定试剂盒测定培养上清液Glu含量。结果 DA处理的原代星形胶质细胞EAAT2水平降低,TAAR1水平增加,培养上清液Glu含量上升。DA处理经TAAR1 siRNA转染后的原代星形胶质细胞,上调EAAT2水平,培养上清液中Glu含量减少;DA处理经TAAR1质粒转染后的原代星形胶质细胞,则EAAT2降低,培养上清液中Glu的含量增加。结论 DA通过影响星形胶质细胞TAAR1-EAAT2信号通路,减弱细胞Glu摄取能力,引起细胞外Glu蓄积,从而损伤星形胶质细胞的功能。     

谷氨酸影响星形胶质细胞表达神经生长因子的实验研究

本文利用双向ＥＬＩＳＡ 法定量检测体外培养乳鼠大脑皮质星形胶质细胞在不同浓度的谷氨酸条件培养基中ＮＧＦ的表达分泌量,观察谷氨酸的调节作用,并利用氯胺酮或ＥＧＴＡ 限制谷氨酸ＮＭ ＤＡ 型受体介导的钙离子内流,观察谷氨酸调节作用的改变。结果表明：体外培养的星状胶质细胞２４ ｈ 能表达分泌ＮＧＦ ３．１２３ ｐｇ／１０５ 细胞;１０ μｍ ｏｌ／Ｌ～１ ｍ ｍ ｏｌ／Ｌ的谷氨酸能显著促进ＮＧＦ表达,其中以１００ μｍ ｏｌ／Ｌ的谷氨酸作用为最强,而１０ ｍ ｍ ｏｌ／Ｌ 的谷氨酸反而起抑制作用;限制谷氨酸ＮＭＤＡ 型受体介导的钙离子内流,能消除谷氨酸的这种调节作用。结果提示：谷氨酸可因其浓度不同促进或抑制星形胶质细胞表达ＮＧＦ,这种调节作用可能通过其ＮＭ ＤＡ 受体介导的钙离子内流来实现。     

活化小胶质细胞致星形胶质细胞激活

目的探讨活化小胶质细胞培养液对星形胶质细胞的影响。方法 LPS激活原代培养小胶质细胞,采用活化的小胶质细胞条件培养液刺激星形胶质细胞,观察星形胶质细胞GFAP及IL-1β和TNFα的表达。结果 LPS刺激后,小胶质细胞OX42表达量上升,IL-1β和TNFα的表达量增高;小胶质细胞条件培养液可致星形胶质细胞激活,GFAP表达量上升,IL-1β和TNFα的表达量增加。结论活化小胶质细胞的条件培养液可致星形胶质细胞激活,激活的小胶质细胞和星形胶质细胞表达前炎症介质IL-1β和TNFα。     

氧气葡萄糖剥夺诱导原代培养的星形胶质细胞释放谷氨酸

目的观察氧气葡萄糖剥夺(OGD)对原代培养的星形胶质细胞谷氨酸释放的影响,并探讨其释放机制。方法原代培养SD大鼠海马区星形胶质细胞,将其分为OGD组和对照组。OGD组的细胞置于不含糖和氧的培养基,37℃,950 mL/L N2和50 mL/L CO2,饱和湿度的培养环境下培养,而对照组细胞则正常培养。缺糖缺氧刺激时长分别为0、15、30、60、90、120 min,采用高效液相色谱,测定细胞外液的谷氨酸浓度。分别选用连接子蛋白43(Cx43)特异性反义寡核苷酸(Cx43-ASODN)和Cx43半通道的阻断剂Gap26预处理星形胶质细胞,采用高效液相色谱,测定细胞外液谷氨酸浓度,观察OGD对其谷氨酸释放的影响。结果与对照组相比较,OGD刺激后,细胞外液谷氨酸浓度升高,并在刺激90 min后,达到峰值,为(5.00±0.30)nmol/mL,显著高于对照组的(2.36±0.15)nmol/mL(P0.05);而OGD条件下,Cx43-ASODN或Cx43半通道阻断剂均可抑制细胞外液谷氨酸浓度的升高,刺激90 min后,细胞外液谷氨酸浓度分别为(4.02±0.18)nmol/mL和(3.93±0.32)nmol/mL,显著低于单纯OGD刺激组(P0.05)。结论 OGD可以诱导星形胶质细胞通过Cx43半通道释放谷氨酸。     

S100A9通过增加小鼠星形胶质细胞的谷氨酸分泌促进神经元损伤

目的:研究钙防卫蛋白S100A9刺激体外星形胶质细胞后细胞外谷氨酸浓度变化及其对神经元影响和调控机制。方法:分离培养新生C57BL/6小鼠大脑皮层星形胶质细胞和神经元;Amplite荧光法检测星形胶质细胞培养上清谷氨酸浓度;Real time RT-PCR和Western Blot分别检测星形胶质细胞谷氨酸转运体(GLT-1) mRNA和蛋白表达;Fluo-4荧光探针法检测星形胶质细胞胞内Ca²⁺浓度;转录组测序并结合KEGG分析筛选星形胶质细胞谷氨酸浓度变化的调控机制;S100A9刺激星形胶质细胞的培养上清(CS)干预神经元后,末端脱氧核苷酸转移酶标记法(TUNEL)检测神经元凋亡,CCK-8试剂盒检测神经元存活。结果:S100A9刺激星形胶质细胞后细胞外谷氨酸浓度增加,GLT-1 mRNA和蛋白表达减少,细胞内Ca²⁺浓度增加。差异表达基因KEGG富集在核因子-κB(NF-κB)信号通路、toll样受体(TLRs)信号通路和肿瘤坏死因子(TNF)信号通路等。培养上清组神经元凋亡率高于对照组。结论:S100A9可能通过激活TLR4/NF-κ...     

氨对星形胶质细胞超微结构的影响

目的：在体外实验条件下观察氨对星状胶质细胞超微结构的影响。材料与方法：用ＮＨ４Ｃｌ造成高高ＮＨ４环境，对体外培养之星形胶质细胞的形态变化进行了超微结构观察。结果：高ＮＨ４环境下，星菜胶质细胞首先表现出损伤性变化，细胞电子密度降低，线粒体、内质网等细胞器肿胀，在胞质内形成许多单位膜包绕的电子密度降低的空泡区域，以后随着氨浓度加大或／和氨作用的时间延长，细胞内成份开始出现增生修复现象，次级溶酶体数量增     

星形胶质细胞谱系及星形细胞瘤起源的研究

各种神经胶质细胞中数目最多、分布最广的星形细胞担负了神经胶质细胞的大部分功能。根据对两种神经组织标志物─ＧＦＡＰ、Ａ－２Ｂ－５抗体的反应不同，将星形细胞分为１型（ＧＦＡＰ＋Ａ－２Ｂ－５－）和２型（ＧＦＡＰ＋、Ａ－２Ｂ－５＋）。研究指出两型星细胞来源于不同祖细胞，而存在两个谱系，星形细胞胶质瘤与星形细胞具有同样的谱系源。对小胶质细胞在星形细胞发生和分化中的作用亦予以阐述。     

GDNF激活星形胶质细胞保护PD模型大鼠黑质多巴胺能神经元

探索在胶质细胞源性神经营养因子(GDNF)保护受损多巴胺(DA)能神经元过程中,星形胶质细胞的可能作用。成年大鼠右侧纹状体内注射6-羟多巴胺(6-OHDA)制备Parkinson病(PD)模型。动物模型右侧黑质内注射GDNF,于注射后第7、14和21d进行动物行为学分析,行黑质节段连续冠状石蜡切片,以抗酪氨酸羟化酶(TH)、胶质原纤维酸性蛋白(GFAP)抗体免疫组化染色,分别显示DA能神经元和激活的星形胶质细胞,光镜观察并进行细胞计数。用免疫印迹法分析注射后第21d黑质内TH、GFAP蛋白表达量,蛋白条带用图像处理仪扫描,LabWorks软件分析处理。结果显示:动物在注射GDNF后第21d,行为学功能出现显著性恢复;TH阳性神经元数量显著增加;在检测的各时间点均可观察到大量的GFAP阳性细胞;TH、GFAP的蛋白表达量显著高于对照组。以上结果提示,黑质内注射GDNF可能通过激活了的星形胶质细胞保护PD模型大鼠黑质DA能神经元。     

星形胶质细胞的可塑性

星形胶质细胞具有可塑性 ,即指其在内外环境变化刺激下 ,在整个生命过程中 ,能改变其自身特性 ,而在表型上呈现出很大程度的可变性。主要表现为细胞大小、形态及数目的变化 ,其中以细胞突起变化最明显。不同发育阶段 ,不同区域的星形胶质细胞可塑性不同。星形胶质细胞可塑性的机制 ,目前认为主要是递质刺激相应的星形胶质细胞受体来实现的     

Action of dopamine and serotonin on the membrane potential of cultured astrocytes

Summary The actions of dopamine, apomorphine and serotonin on the membrane potential of cultured astrocytes from rat spinal cord and striatum were examined. All three compounds caused a hyperpolarization of the majority of astrocytes tested. A small number of cells was depolarized and on a relatively large number of cells the amines had no effect. The dopamine antagonists cis-flupenthixol and domperidone reversibly blocked the effects of dopamine whereas the action of serotonin was antagonized by ketanserin. It is therefore concluded that the effects of both amines are due to activation of specific dopamine and serotonin receptors, respectively. Our electrophysiological data together with autoradiographic binding studies provide evidence that astrocytes possess receptors for dopamine and serotonin in addition to adrenoceptors and histamine receptors.     

Cytokine-induced enhancement of calcium-dependent glutamate release from astrocytes mediated by nitric oxide

Cytokines are produced in the central nervous system (CNS) and exhibit various effects on neurons, microglia, and astrocytes. Astrocytes can release chemical transmitters, including glutamate, in a calcium-dependent manner, which may mediate communication between neurons and astrocytes. To date, no studies have been conducted on the effects of cytokines on calcium-dependent glutamate release from astrocytes. Here, we studied the effects of cytokines on calcium-dependent glutamate release. Cytokines enhanced glutamate release and induced the expression of inducible nitric oxide synthase (iNOS) and the production of nitric oxide (NO). The inhibition of iNOS eliminated the cytokine-induced enhancement of glutamate release, and treatment with a NO donor, even in the absence of cytokines, increased glutamate release. Thus, cytokines enhance glutamate release, and this enhancement is mediated by NO.     

Enhanced GLT-1 mediated glutamate uptake and migration of primary astrocytes directed by fibronectin-coated electrospun poly-l-lactic acid fibers

Bioengineered fiber substrates are increasingly studied as a means to promote regeneration and remodeling in the injured central nervous system (CNS). Previous reports largely focused on the ability of oriented scaffolds to bridge injured regions and direct outgrowth of axonal projections. In the present work, we explored the effects of electrospun microfibers on the migration and physiological properties of brain astroglial cells. Primary rat astrocytes were cultured on either fibronectin-coated poly-l-lactic acid (PLLA) films, fibronectin-coated randomly oriented PLLA electrospun fibers, or fibronectin-coated aligned PLLA electrospun fibers. Aligned PLLA fibers strongly altered astrocytic morphology, orienting cell processes, actin microfilaments, and microtubules along the length of the fibers. On aligned fibers, astrocytes also significantly increased their migration rates in the direction of fiber orientation. We further investigated if fiber topography modifies astrocytic neuroprotective properties, namely glutamate and glutamine transport and metabolism. This was done by quantifying changes in mRNA expression (qRT-PCR) and protein levels (Western blotting) for a battery of relevant biomolecules. Interestingly, we found that cells grown on random and/or aligned fibers increased the expression levels of two glutamate transporters, GLAST and GLT-1, and an important metabolic enzyme, glutamine synthetase, as compared to the fibronectin-coated films. Functional assays revealed increases in glutamate transport rates due to GLT-1 mediated uptake, which was largely determined by the dihydrokainate-sensitive GLT-1. Overall, this study suggests that aligned PLLA fibers can promote directed astrocytic migration, and, of most importance, our in vitro results indicate for the first time that electrospun PLLA fibers can positively modify neuroprotective properties of glial cells by increasing rates of glutamate uptake.     

Quantitative analysis of EAAT4 promoter activity in neurons and astrocytes of mouse somatic sensory cortex

EAAT4–eGFP BAC reporter transgenic adult mice were used to detect EAAT4 gene expression in individual cells of cerebral cortex, and eGFP fluorescence was measured to compare EAAT4 promoter activity in different cells. Most eGFP+ cells were neurons; only rare GFAP+ profiles were eGFP+. About 10% of NeuN+ cells was eGFP+, and the percentage of NeuN/eGFP co-localization varied from 2 to 20% of NeuN+ cells throughout cortical layers: layers I and II–III showed the highest values of co-localization, layer IV the lowest. The intensity of eGFP fluorescence did not exhibit laminar variations. Finally, we observed that EAAT4 promoter activity in cortical neurons was 10% of that measured in cerebellar Purkinje cells, i.e., the cells displaying the highest intensity in the CNS. These results extend our knowledge on EAAT4 expression in the cerebral cortex of adult mice, and suggest that the role of EAAT4 in cortical glutamatergic transmission may be more important than previously thought.     

Impaired Ca-signaling in astrocytes from the Ts16 mouse model of Down syndrome

The trisomy 16 mouse model of Down syndrome has been used to compare calcium (Ca)-homeostasis and Ca-signaling in astrocytes from trisomic mice and from diploid littermates. Ratio calcium-imaging of Fura-2/AM loaded primary astroglial cultures prepared from the hippocampus shows that resting Ca levels are on average significantly higher in trisomic than in the control astrocytes (280 vs. 120 nM). Serotonin (3 μM) and glutamate (30–300 μM) evoked transient Ca-increases from 400 to 600 nM in euploid but from only 20 to 150 nM in trisomic astrocytes. Imaging of ATP-driven Ca-accumulation in cellular organelles revealed a significantly stronger uptake of Ca in trisomic astrocytes that might buffer cytosolic Ca-increases. Our results demonstrate major disturbances in Ca-signaling in trisomic astrocytes that are likely to be of pathophysiological relevance.     

GRK5对大鼠星形胶质细胞活化的作用及其机制研究

目的:探讨培养新生大鼠皮层星形胶质细胞G蛋白偶联受体激酶5(GRK5)基因沉默后核因子κB(NF-κB)表达的变化及其与胶质细胞活化、炎症反应和氧化应激的关系。方法:采用分别或联合RNA干扰沉默GRK5基因表达与NF-κB抑制剂N-乙酰半胱氨酸干预进行实验分组。利用免疫荧光、实时定量PCR和Western blotting观察GFAP与活性caspase-3表达,细胞分泌TNF-α与NO的浓度,p65、TNF-α、IL-1β和iNOS的表达情况等。结果:GRK5 siRNA刺激星形胶质细胞活化,并检测到NF-κB表达增多(P0.01),TNF-α、IL-1β和iNOS mRNA表达水平增高(P0.01),细胞分泌TNF-α和NO增多(P0.01),活性caspase-3表达增多(P0.01)。采用GRK5 siRNA+NF-κB抑制剂联合干预可部分逆转GRK5 siRNA引起的上述变化(P0.05)。结论:GRK5基因沉默可能通过刺激NF-κB表达增多引起星形胶质细胞活化。GRK5的正常表达可能具有抑制星形胶质细胞活化相关炎症反应及氧化应激的作用。     

染料木黄酮对氨诱导的星形胶质细胞NF-κB活化的影响

目的:探讨染料木黄酮对氨所致星形胶质细胞NF-κB活化的影响及其机制。方法:以氯化铵刺激原代培养的星形胶质细胞,建立高血氨模型,Western blot检测星形胶质细胞中ERK、Akt及核因子κB(NF-κB)的活化。结果:AG1478及染料木黄酮可显著抑制氨诱导的星形胶质细胞ERK及Akt的活化。LY294002、染料木黄酮及AG1478可显著抑制氨诱导的星形胶质细胞NF-κB核转位。结论:染料木黄酮可显著抑制氨诱导的星形胶质细胞ERK活化和Akt介导的NF-κB活化,这可能是该天然物质抑制星形胶质细胞水肿的重要机制。     

右美托咪定对大鼠脑缺血再灌注损伤后星形胶质细胞的影响

目的: 通过观察右美托咪定(DEX)对大鼠脑缺血再灌注损伤后星形胶质细胞的影响,探讨DEX对抗脑缺血再灌注损伤的作用及其机制。方法: 采用大脑中动脉栓塞法建立大鼠局灶性脑缺血再灌注模型,将SD大鼠随机分为假手术组、单纯脑缺血再灌注组、DEX预处理1组(缺血前30 min腹腔给予DEX 20 μg/kg)及DEX预处理2组(缺血前30 min腹腔给予DEX 40 μg/kg)。缺血再灌注24 h后,观察大鼠神经功能缺失评分,通过HE染色了解脑梗塞后脑组织的病理学变化,采用免疫组化和蛋白免疫印迹方法观察缺血后脑组织星形胶质细胞的变化。结果: DEX预处理能显著改善大鼠神经功能缺失评分,减小大鼠梗死面积,减少缺血区胶质纤维酸性蛋白(GFAP)阳性星形胶质细胞和肿瘤坏死因子α(TNF-α)阳性星形胶质细胞,降低GFAP表达水平。结论: DEX对缺血再灌注损伤的脑组织具有保护作用,其作用机制可能与抑制星形胶质细胞激活有关。     

Excitatory nature of dopamine in the nigro-caudate pathway

Summary Inputs from the substantia nigra (SN) to the caudate nucleus (Cd) and the effects of electrophoretic dopamine on Cd neurones were studied in cats anaesthetized with pentobarbitone with intracellular techniques. Single shock electrical stimulation of the SN or the medial forebrain bundle (MFB) induced monosynaptic EPSPs in Cd neurones. Dopamine depolarized Cd neurones and chlorpromazine suppressed the SN or MFB induced EPSPs. Appropriate controls indicate that the drug effects were not artifactual. Some recorded neurones were identified by procion yellow dye injection as the medium-size intrinsic Cd neurones.M. Sugimori is an academic staff member of Wayne State University while on a leave of absence from Kanazawa University, School of Medicine, Department of Physiology, Kanazawa, Japan.