局灶脑缺血区星形胶质细胞可塑性变化的实验研究

为了探索星形胶质细胞在慢性局灶脑缺血区的分布以及形态和数量变化的时期 ,进而探讨其在脑缺血灶恢复中的作用 ,本研究运用免疫组织化学技术对大鼠进行了研究。结果证明 :胶质纤维酸性蛋白阳性星形胶质细胞在脑梗塞灶的周围发生肥大和增生性改变 ,其突起的变化尤为显著 ;粗大的突起呈纤维状 ,并相互交织呈密集的网 ,其末端向脑梗塞灶的中央延伸。其变化发生于脑缺血第 1周 ,脑缺血第 2周最显著 ,在 6周的脑缺血期间 ,显示持续性变化。 S- 10 0阳性星形胶质细胞在脑梗塞灶周围区的肥大和增生性变化 ,发生于脑缺血第 3d,并持续到脑缺血 4周 ,其形态学改变没有胶质纤维酸性蛋白阳性星形胶质细胞显著。本研究提示慢性局灶脑缺血诱导星形胶质细胞发生形态学的可塑性变化 ,这种变化积极地参与脑梗塞灶的修复过程     

局灶脑梗塞小胶质细胞的可塑性变化及谷氨酸转运体表达

为了探讨小胶质细胞在急性局灶脑梗塞的可塑性变化及其谷氨酸转运体的表达 ,运用免疫组织化学和免疫荧光双标记技术对大鼠皮质光化学局灶性脑梗塞后小胶质细胞的反应及其谷氨酸转运体表达进行了研究。结果显示 ,光化学局灶性脑梗死后小胶质细胞明显活化 ,其形态在脑梗塞半暗带区以高分枝状和杆状为主 ,梗塞灶中心为阿米巴形和圆形。脑梗塞的早期以高分枝状和杆状为主 ,脑梗塞的晚期以阿米巴形和圆形小胶质细胞为主。谷氨酸转运体 EAAT2主要在缺血周边的半暗带区表达 ,呈网状环绕在神经元周围 ,共聚焦显微镜扫描见与 OX42标记的小胶质细胞双重标记。结论 :本研究提示急性局灶脑梗塞后发生可塑性变化的小胶质细胞 ,通过增强 EAAT2的表达积极地参与脑梗塞的修复过程。     

星形细胞活性及GFAP在评价脑梗死中的作用及意义

目的:观察星形胶质细胞的超微结构及胶质纤维酸性蛋白(GFAP)脑梗死后的变化,并探讨GFAP在急性脑梗塞后的作用。方法:用双肾双夹易卒中型肾血管性高血压鼠(RHRSP)复制右大脑中动脉闭塞(MCAO)模型,分MCAO后1、3、6、9周末4个时间组,每组均进行脑梗死灶边缘区(A区),近顶叶皮层的远隔区(B区),对侧皮层与A区相对应的镜区(C区)的电镜观察,并测定各区的GFAP阳性细胞数目及光密度值。结果:脑梗死后星形细胞在全脑的增殖均较活跃。在脑梗死后GFAP阳性细胞数在边缘区最高,B区次之,C区最少。在缺血时间上,其改变以MCAO后1周末最高,3-6周末次之,9周末最少。GFAP阳性细胞浆平均光密度值变化情况与GFAP阳性细胞数目变化基本相同。结论:星形胶质细胞增殖程度和脑梗死后脑组织病变程度可用GFAP的表达值进行评价,增殖的星形胶质细胞在脑梗死后脑组织结构的修复中起着重要的作用。     

脂多糖对大鼠中脑和桥脑内Fos、GFAP、OX42表达的影响

目的 探讨单次腹腔注射脂多糖(LPS),中脑和桥脑神经元、星形胶质细胞和小胶质细胞的可塑性变化。方法 抗Fos蛋白、抗胶质原纤维酸性蛋白(GFAP)、抗特异性标记小胶质细胞(OX42)和抗Fos／GFAP双重免疫组织化学标记法。结果 Fos阳性神经元分布于上丘、中脑导水管周围灰质、臂旁核和蓝斑。Fos蛋白在注射后30min。表达,1～3h为高峰。GFAP阳性星形胶质细胞胞体变大,突起增粗,细胞密度增加,30min出现表达,1h为高峰,3h后减少。OX42阳性小胶质细胞首先于脑室周围灰质表达,注射后6h达到高峰,胞体变大,全脑分布。相应于Fos阳性神经元分布区域,GFAP阳性星形胶质细胞和OX42阳性小胶质细胞深染和密集。结论 上丘、臂旁核、蓝斑内神经元、星形胶质细胞、小胶质细胞可能参与神经免疫调节,臂旁核可能为此调节通路的中继站之一。     

空间辨别性学习记忆活动对大鼠杏仁复合体内星形胶质细胞的影响

目的:探讨杏仁复合体内星形胶质细胞在学习记忆过程中的作用,并提供形态学依据。方法:雄性SD大鼠随机分为对照组、游水组、模型组。应用Morris水迷宫训练大鼠建立空间辨别性学习记忆动物模型,用免疫细胞化学法显示杏仁复合体内神经纤维胶质酸性蛋白(GFAP)免疫阳性的星形胶质细胞。结果:大鼠杏仁复合体内星形胶质细胞数量、大小、突起长度及突起分级呈现出由对照组向游水组再到模型组递增趋势;大鼠杏仁复合体内GFAP免疫阳性产物灰度值由对照组向游水组到模型组呈逐渐减少的趋势。模型组中14 d的GFAP免疫阳性产物灰度值低于7d和21d的。结论:大鼠杏仁复合体内星形胶质细胞参与空间辨别性学习记忆过程,在形态和GFAP表达上均呈时间和空间变化。     

海马内注射LPS后诱导大鼠皮质星形胶质细胞活化和PirB的表达

目的:探讨海马内注射LPS(lipopolysaccharide,LPS)后,大鼠皮质神经元和星形胶质细胞PirB(paired-immunoglobulin-like receptor B)的表达变化。方法:成年SD大鼠,分为对照组和实验组,用免疫组织化学法检测大鼠脑皮质PirB的表达及星形胶质细胞GFAP的表达变化,免疫荧光双重标记技术,观察星形胶质细胞与PirB阳性细胞的共存。结果:PBS注射的对照组动物脑皮质Ⅴ层内可见PirB阳性神经元样细胞,呈圆形、卵圆形和锥体形,免疫反应产物呈棕色、主要位于细胞膜上;海马内注射LPS 30 d后,PirB阳性神经元样细胞和PirB阳性神经胶质样细胞主要分布于皮质Ⅳ、Ⅴ层,免疫反应产物位于胞质和突起内;另外,可见大鼠梨状皮质、内嗅皮质内GFAP阳性星形胶质细胞明显被激活,表现为细胞胞体相对增大,突起变粗。PirB分别和MAP-2、GFAP、CD11b免疫荧光双重标记染色显示:PirB和MAP-2阳性神经元的胞体存在共定位;PirB与GFAP阳性染色存在部分共定位,但未见PirB与CD11b阳性染色双标细胞。结论:LPS能诱导大鼠皮质星形胶质细胞活化和PirB蛋白表达上调,而且部分活化的星形胶质细胞表达PirB,PirB可能参与脑内炎症突触可塑性改变和学习记忆功能缺失的免疫调节。     

低渗刺激后大鼠视上核内星形胶质细胞和神经元的可塑性改变及其相互关系

为观察低渗刺激后大鼠视上核(SON)内星形胶质细胞和神经元的可塑性反应及其两者在反应时间和空间上的相互关系,我们采用大鼠尾静脉注射 5. 5ml/kg低渗盐水(0. 83% 葡萄糖+ 0. 3% NaCl)制作模型,应用抗Fos、抗胶质原纤维酸性蛋白(GFAP)单标记,以及抗Fos/抗GFAP双标记、抗Fos/抗血管加压素 (VP) /抗GFAP三标记的免疫组化方法。结果发现:在SON中GFAP阳性星形胶质细胞数量在刺激后 15min增加,其胞体肥大,突起伸长变粗, 45min达高峰。Fos阳性星形胶质细胞胞核呈蓝黑色小点,刺激后 15~45min达高峰, 90min明显减少;Fos阳性神经元胞核较大,刺激后 15min未见表达, 45min少量表达, 90min表达增加。该结果表明低渗刺激后,SON内星形胶质细胞的Fos表达早于神经元,三重标记显示星形胶质细胞与神经元关系密切,提示SON内星形胶质细胞可能在低渗刺激的调节中发挥一定作用。     

缺血再灌注对大鼠神经元与星形胶质细胞的影响

应用免疫组织化学单标记法分别观察大鼠在大脑中动脉阻塞再灌注时胶质原纤维酸性蛋白(GFAP)和Fos蛋白在大脑皮质内表达的时间规律,并用免疫组织化学双重标记法观察GFAP和Fos蛋白表达的相互关系。结果发现在缺血1h再灌注2h时,大脑皮层的星形胶质细胞被激活,细胞体积增大,突起粗大,呈GFAP阳性。星形胶质细胞的反应直至48h依然强烈。被激活的星形胶质细胞和神经元表达Fos蛋白,并呈现时程变化规律。结果提示星形胶质细胞可能和神经元一起参与了大脑皮层缺血再灌注后的变化。     

细胞外调节蛋白激酶在体外培养下大鼠大脑皮质星形胶质细胞的表达

目的:研究大鼠大脑皮质星形胶质细胞细胞外调节蛋白激酶(ERK)表达.方法:用生后2～3d SD大鼠,在无菌条件下取大脑皮质,制备细胞悬液,以GFAP鉴定星形胶质细胞;用免疫细胞化学方法研究星形胶质细胞ERK1表达.结果:星形胶质细胞的纯度达95%以上,ERK1免疫阳性物质呈棕黄色,分布于星形胶质细胞胞体与突起中.结论:培养的大鼠星形胶质细胞表达ERK1,其可能与星形胶质细胞信号转导有关.     

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。     

Astrocyte phenotype in relation to Alzheimer-type pathology in the ageing brain

Astrocyte pathology occurs in association with Alzheimer's disease (AD) and in brain ageing, but is poorly characterised. We sought to define the detailed cellular pathology of astrocytes, the extent of population variation and the relationship to Alzheimer-type changes in a population-based cohort. Three staining patterns were associated with GFAP and excitatory amino acid transporter 2 (EAAT2): minimal, moderate or extensive immunoreactivity. GFAP and EAAT2 expression were inversely related (p=0.015), with trends to increased expression of GFAP (p=0.019) and decreased expression of EAAT2 (p=ns) with increasing Braak stage. GFAP and EAAT2 correlated incompletely with beta-amyloid and tau immunoreactivity. However, gliosis increased with increasing burden of neuritic (p=0.011), but not diffuse (p=ns), plaques. Double-staining revealed distinct subsets of astrocytes; GFAP(+)EAAT(-), GFAP(-)EAAT(+), or GFAP(+)EAAT(+). In contrast to the variation in GFAP and EAAT2, levels of EAAT1 and S100B showed consistent staining patterns. Alzheimer-type pathology only partially explains the variation in gliosis and astrocyte functional markers, suggesting that other factors contribute to the population variance in astrocyte pathology.     

大鼠束缚后脑内星形胶质细胞的反应

为了探讨束缚后大鼠脑内星形胶质细胞的反应,本实验将大鼠束缚于小的塑料桶内1、3或6 h,于解束后30 min处死,正常大鼠不被束缚作为对照。脑组织进行抗glial fibrillary acidic-protein(GFAP)免疫组织化学染色。结果显示:在正常大鼠脑内有少数散在静止状态的星形胶质细胞,表现为胞体小、突起细、GFAP淡染,缺乏机能定位分布特点;束缚后脑内星形胶质细胞表现为胞体肥大、突起变粗、GFAP深染、形成激活状态,其分布有明显的机能定位特点,表达于与应激反应调节相关的核团,主要有(1)端脑:扣带回、新皮质(尤其是第Ⅲ和V层)、隔外侧核、杏仁中央核;(2)间脑:丘脑室旁核、外侧膝状体、内侧膝状体、下丘脑的视上核、室旁核、第三脑室室周区、弓状核;(3)脑干:中脑的上丘浅层、中脑导水管周围灰质、下丘的皮质部;脑桥的臂旁外侧核、蓝斑、A5区;延髓的耳蜗核、延髓内脏带(MVZ)等处。反应性星形胶质细胞表达的时程变化是束缚1 h最高,3 h次之,6 h最少。本文结果表明,大鼠被束缚后全脑多处核团的星形胶质细胞发生不同程度的改变,随着束缚时间的延长,动物产生适应性,星形胶质细胞表达减少。     

Excitatory amino acid transporters EAAT‐1 and EAAT‐2 in temporal lobe and hippocampus in intractable temporal lobe epilepsy

Intractable temporal lobe epilepsy (TLE) is an invalidating disease and many patients are resistant to medical treatment. Increased glutamate concentration has been found in epileptogenic foci and may induce local over‐excitation and cytotoxicity; one of the proposed mechanisms involves reduced extra‐cellular clearance of glutamate by excitatory amino acid transporters (EAAT‐1 to EAAT‐5). EAAT‐1 and EAAT‐2 are mainly expressed on astroglial cells for the reuptake of glutamate from the extra‐cellular space. We have studied the expression of EAAT‐1 and EAAT‐2 in the hippocampus and temporal lobe in 12 patients with TLE by immunhistochemistry and densitometry. The expression of EAAT‐1 and EAAT‐2 was reduced to approximately 40% and 25%, respectively, in CA1 of the hippocampus. In the same area, an increased expression of glial fibrillary acid protein (GFAP) at 90% reflected molecular rearrangements and upregulation of GFAP in the existing astrocytes as Ki‐67 staining failed to demonstrate any signs of astrocytic proliferation. The aetiology of the reduced expression of EAAT‐1 and EAAT‐2 remains unclear. The downregulation of EAAT‐1 and EAAT‐2 may be an adaptive response to neuronal death or it may be a causative event contributing to neuronal death. Further studies of the EAATs and their function are needed to clarify the mechanisms and significance of EAAT‐1 and EAAT‐2 disappearance in TLE.     

Selective overexpression of excitatory amino acid transporter 2 (EAAT2) in astrocytes enhances neuroprotection from moderate but not severe hypoxia-ischemia

Attempts have been made to elevate excitatory amino acid transporter 2 (EAAT2) expression in an effort to compensate for loss of function and expression associated with disease or pathology. Increased EAAT2 expression has been noted following treatment with beta-lactam antibiotics, and during ischemic preconditioning (IPC). However, both of these conditions induce multiple changes in addition to alterations in EAAT2 expression that could potentially contribute to neuroprotection. Therefore, the aim of this study was to selectively overexpress EAAT2 in astrocytes and characterize the cell type specific contribution of this transporter to neuroprotection. To accomplish this we used a recombinant adeno-associated virus vector, AAV1-glial fibrillary acidic protein (GFAP)-EAAT2, designed to selectively drive the overexpression of EAAT2 within astrocytes. Both viral-mediated gene delivery and beta-lactam antibiotic (penicillin-G) treatment of rat hippocampal slice cultures resulted in a significant increase in both the expression of EAAT2, and dihydrokainate (DHK) sensitive glutamate uptake. Penicillin-G provided significant neuroprotection in rat hippocampal slice cultures under conditions of both moderate and severe oxygen glucose deprivation (OGD). In contrast, viral-mediated overexpression of EAAT2 in astrocytes provided enhanced neuroprotection only following a moderate OGD insult. These results indicate that functional EAAT2 can be selectively overexpressed in astrocytes, leading to enhanced neuroprotection. However, this cell type specific increase in EAAT2 expression offers only limited protection compared to treatment with penicillin-G.     

地塞米松和苯妥英钠对癫痫大鼠脑内的GFAP和Fos表达的抑制作用

目的：探讨糖皮质激素（GC）的抗痫效应和抗痫机制。方法：动物行为学观察和免疫细胞化学染色。结果：戊四氮（PTZ）可诱发癫痫大发作,如诺在注入PTZ前30min先注入地塞米松或苯妥英钠（DPH）能减轻或抑制大鼠癫痫发作症状。免疫细胞化学染色结果表明,PTZ致痫组大鼠大脑皮质、海马回、齿状有大量肥大的胶质原纤维酸性蛋白（GFAP）阳性的星形胶质细胞。GC或DPH抗痫组GFAP免疫反应明显减弱,阳性细胞数量减少,突起短而少,Fos蛋白在PTZ组大鼠致痫后1－1．5h有大量表达,而在上述两抗痫组显著少于PTZ致痫组。结论：1．通过与苯妥英钠（传统抗痫药）的抗痫效果相比较,进一步证明糖皮质激素具有抗痫效应。2．糖皮质激素的抗痫机制可能与抑制星形胶质细胞的活动有关。3．Fos蛋白表达的变化与癫痫活动有直接关系。