反应性星形胶质细胞与轴突再生

星形胶质细胞是中枢神经系统中最丰富的胶质细胞类型,中枢神经系统损伤后,星形胶质细胞在形态和分子表达上发生变化形成反应性星形胶质细胞。反应性星形胶质细胞对轴突再生有着双重影响。一方面,反应性星形胶质细胞能分泌神经营养因子,具有神经保护和修复作用;另一方面,反应性星形胶质细胞若过度增殖形成胶质瘢痕,则抑制轴突再生,不利于神经功能恢复。     

星形胶质细胞与癫痫

星形胶质细胞是中枢神经系统的主要支持成分,参与多种生理、病理功能。星形胶质细胞具有对各种神经损害产生强烈反应的特性。在病理条件下,星形胶质细胞内多种细胞因子表达增加．对疾病的神经损害具有重要影响。近年来,星形胶质细胞在癫痫发生、发展中的作用日益受到重视。１星形胶质细胞解剖、生理星形胶质细胞起源于外胚层,分布于中枢神经系统的各个部分。星形胶质细胞发出突起附着在毛细血管壁上或脑和脊髓表面形成胶质界膜,将中枢神经系统与中胚层组织分开。在中枢神经系统内部,胶质细胞充填于神经元胞体及其突起之间,并将突触结…     

星形胶质细胞在多发性硬化发病中的作用机制

星形胶质细胞是中枢神经系统中数量最多的胶质细胞,其生理功能为支持和营养神经元,参与免疫调节和神经递质代谢,支持血-脑脊液屏障,调节神经细胞内、外离子浓度等。星形胶质细胞在多发性硬化(multiple sclerosis,MS)中反应性增生,此现象称为星形胶质细胞活化。活化的星形胶质细胞一方面产生一些具有神经损伤的细胞因子,另一方面能分泌有利于神经系统恢复的因子来促进神经生长和修复。因而星形胶质细胞在MS中具有双重角色。在MS发病机制中明确星形胶质细胞在不同发病阶段的作用倾向,可能为MS的治疗提供新的治疗策略。     

星形胶质细胞与炎性脱髓鞘疾病

髓鞘脱失后星形胶质细胞被迅速活化 ,通过形态、免疫显型和功能改变 ,发挥免疫调节 ,对胶质疤痕形成和神经组织修复具有双向作用。星形胶质细胞活化在炎性脱髓鞘疾病中具有双重作用。     

重新评估星形胶质细胞的功能作用

星形胶质细胞（Astrocyte）是中枢神经系统胶质细胞的主要组成部分,目前认为星形胶质细胞除了对神经元提供营养支持保护、物质代谢、参与血脑屏障形成和免疫功能外,还具有神经干细胞的特性、参与疼痛调节机制和神经信号传递处理、对脑的高级功能活动具有重要作用。     

星形胶质细胞对神经回路形成作用研究进展

星形胶质细胞(astrocytes, Ast)是哺乳动物大脑中含量最多的神经胶质细胞,它在维持血脑屏障、调节局部血流量、抗氧化和代谢支持以及神经回路的形成上起着重要的作用。星形胶质细胞可以通过各种分泌信号控制突触的形成、成熟和修剪。近年来,在突触缺陷所引起的一系列神经精神疾病中也可以发现星形胶质细胞的身影,了解星形胶质细胞在神经回路发育和功能的调控,有助于对这一系列健康疾病问题提供新的治疗手段。神经回路的形成主要包括三个过程,首先,轴突和树突之间形成未成熟突触;其二,突触成熟,沉默突触转化为活性突触;其三,敲除和修剪过量及不合格突触。星形胶质细胞可以控制突触形成、成熟和消除的每个阶段以支持神经回路的发生和维护。现将星形胶质细胞对神经回路形成的调节作用研究进展综述如下。     

星形胶质细胞源性因子对神经干细胞分化的实验研究

目的探讨星形胶质细胞源性因子对神经干细胞分化的影响。方法分离和培养新生大鼠脑组织的神经干细胞;采用差速贴壁法和振荡法分离纯化星形胶质细胞,用免疫细胞化学染色法,胶质纤维酸性蛋白(GFAP)标记星形胶质细胞,进行细胞的纯度鉴定;将星形胶质细胞和神经干细胞在互不接触的情况下进行共培养,免疫荧光法观察神经干细胞分化后神经元特异性烯醇化酶(NSE)、GFAP和酪氨酸羟化酶(TH)的表达。结果纯化的星形胶质细胞GFAP抗体标记阳性,细胞纯度达98%;星形胶质细胞与神经干细胞共培养时,神经干细胞贴壁分化加快,NSE阳性细胞及TH阳性细胞明显多于对照组(P<0·05)。结论星形胶质细胞源性因子可快速诱导神经干细胞向神经元细胞、包括多巴胺神经元细胞分化,提示星形胶质细胞支持神经元发生。     

RNAi靶向沉默预处理星形胶质细胞胶质细胞源性神经营养因子对神经元凋亡的影响

研究表明外源性的胶质细胞源性神经营养因子可对脑缺血损伤时的神经元有保护作用,但关于内源性的胶质细胞源性神经营养因子的神经元保护作用目前机制不清。鉴于此,实验以正常培养的星形胶质细胞培养基,胶质细胞源性神经营养因子高表达星形胶质细胞培养基和采用RNAi技术沉默胶质细胞源性神经营养因子表达的星形胶质细胞培养基,作用于缺血神经元,观察不同条件培养基对神经元凋亡的影响。结果验证RNAi靶向沉默预处理星形胶质细胞胶质细胞源性神经营养因子的表达可促进神经元凋亡,氧糖剥夺预处理可上调星形胶质细胞的胶质细胞源性神经营养因子的表达,能明显降低神经元的凋亡。     

大鼠嗅鞘细胞和星形胶质细胞对神经干细胞分化作用的比较研究

目的比较大鼠嗅鞘细胞与星形胶质细胞对神经干细胞分化的影响。方法分别从新生SD大鼠嗅球、海马、皮质分离、培养嗅鞘细胞、神经干细胞和星形胶质细胞。收集嗅鞘细胞、星形胶质细胞及其上清液,分别对神经干细胞(neural stem cells,NSCs)进行诱导分化,倒置显微镜下观察细胞的生长情况,并采用免疫组化法对分化细胞鉴定和计数。结果嗅鞘细胞组分化为神经元比率高于星形胶质细胞组(P<0.01)。结论嗅鞘细胞较星形胶质细胞能更好地促进神经干细胞分化为神经元。     

影响神经干细胞定向分化因素的研究进展

神经干细胞(NSC)具有自我更新和多分化潜能属性,可分化产生神经元、星形胶质细胞和少突胶质细胞,这使得NSC移植替代神经系统疾病中丢失的细胞成为可能.NSC在胚胎和成体中枢神经系统均存在.NSC移植在体内环境下(尤其是非神经发生区域)绝大多数分化成胶质细胞(星形胶质细胞),有可能会加重胶质瘢痕形成.在中枢神经系统疾病的NSC细胞替代治疗策略中,NSC分化成合适的细胞类型显得格外重要.现就影响NSC定向分化的因素作一综述.     

NF-kappaB and IkappaBalpha expression following traumatic brain injury to the immature rat brain

NF-kappaB is one of the most important modulators of stress and inflammatory gene expression in the nervous system. In the adult brain, NF-kappaB upregulation has been demonstrated in neurons and glial cells in response to experimental injury and neuropathological disorders, where it has been related to both neurodegenerative and neuroprotective activities. Accordingly, the aim of this study was to evaluate the cellular and temporal patterns of NF-kappaB activation and the expression of its endogenous inhibitor IkappaBalpha following traumatic brain injury (TBI) during the early postnatal weeks, when the brain presents elevated levels of plasticity and neuroprotection. Our results showed that cortical trauma to the 9-day-old rat brain induced a very fast upregulation of NF-kappaB, which was maximal within the first 24 hours after injury. NF-kappaB was mainly observed in neuronal cells of the degenerating cortex as well as in astrocytes located in the corpus callosum adjacent to the injury, where a pulse-like pattern of microglial NF-kappaB activation was also found. In addition, astrocytes of the corpus callosum, and microglial cells to a lower extent, also showed de novo expression of IkappaBalpha within the time of NF-kappaB activation. This study suggests an important role of NF-kappaB activation in the early mechanisms of neuronal death or survival, as well as in the development of the glial and inflammatory responses following traumatic injury to the immature rat brain.     

白细胞膜微粒在动脉粥样硬化发生发展的作用

白细胞膜微粒是白细胞在活化、损伤或凋亡时,从其表面释放的富含脂质的膜囊泡,其在内皮细胞损伤、血管功能障碍、氧化应激、炎症反应及细胞之间的信号传导等方面发挥重要作用。近来研究发现,在动脉粥样硬化基础上发生的心脑血管疾病、血栓栓塞性疾病、代谢性疾病和恶性高血压病等疾病中白细胞膜微粒明显增高。文中就白细胞膜微粒对动脉粥样硬化发生发展的作用进行概述。     

Wistar大鼠实验性自身免疫性脑脊髓炎胶质纤维酸性蛋白变化的研究

目的通过建立实验性自身免疫性脑脊髓炎(EAE)模型研究Wistar大鼠脑内神经脱髓鞘后星形胶质细胞损伤随时间变化的规律。方法对Wistar大鼠经足垫注射豚鼠脊髓匀浆制作EAE模型,并于不同时间点将其处死,取脑组织进行免疫组化染色及图像分析检测脑组织中胶质纤维酸性蛋白(GFAP)水平并与健康对照组进行比较。结果GFAP阳性细胞随损伤时间呈先上升后下降的变化趋势,于发病后第7天表达最高,第21天恢复正常。其中发病后第7、14天GFAP阳性细胞突起增长、增粗,染色加深。结论EAE模型中星形胶质细胞可能参与了脑组织损伤后的修复过程,其标志性蛋白GFAP水平随损伤时间呈规律性改变。     

Colocalization of angiotensinogen and glial fibrillary acidic protein in astrocytes in rat brain

Angiotensinogen is produced in the brain, but its precise localization and the cells in the central nervous system producing it are unknown. We have performed a double staining test for angiotensinogen and glial fibrillary acidic protein in rat brain and report here that these proteins colocalize in astrocytes.     

Multifocal glial nodules in a case of Duchenne muscular dystrophy with severe mental retardation

A case of Duchenne muscular dystrophy with multifocal hamartomatous glial nodules in the cerebral cortex is reported. The patient had suffered severe mental retardation since boyhood, dying of aspiration pneumonia at the age of 23 years. Post-mortem examination revealed an atrophic brain with normal gyri. Microscopically, multifocal small nodules composed of bizzare astrocytic cells, multinucleated cells, neuron-like cells, small astrocytes and glial fibers were found in the first, fifth and sixth layers of the prefrontal cortex. Some of the bizarre cells showed intense immunoreactivity for glial fibrillary acidic protein and moderate to very weak reactivity for ubiquitin, tau protein and αB crystallin but no immunoreactivity for neurofilament and synaptophysin, suggesting that these cells were of astrocytic origin. The nodules were considered to be due to hamartomatous changes that had occurred in the early stage of brain development, and that might have been partly responsible for the pathogenetic mechanisms of mental retardation.     

Glial influence on the blood brain barrier

The Blood Brain Barrier (BBB) is a specialized vascular structure tightly regulating central nervous system (CNS) homeostasis. Endothelial cells are the central component of the BBB and control of their barrier phenotype resides on astrocytes and pericytes. Interactions between these cells and the endothelium promote and maintain many of the physiological and metabolic characteristics that are unique to the BBB. In this review we describe recent findings related to the involvement of astroglial cells, including radial glial cells, in the induction of barrier properties during embryogenesis and adulthood. In addition, we describe changes that occur in astrocytes and endothelial cells during injury and inflammation with a particular emphasis on alterations of the BBB phenotype. GLIA 2013;61:1939–1958     

Localisation and expression of metallothionein immunoreactivity in the developing sheep brain

Metallothioneins are small cysteine-rich proteins that bind heavy metals. In higher mammals there are complex families of metallothionein isoforms, which are well characterised at the DNA level but less so in terms of their cellular expression and function. In particular, little is known about the localisation of metallothionein in the developing mammalian brain. In this study, using sheep fetuses, we have shown that metallothionein 1 and 2 isoform expression undergoes shifts in regional and cellular localisation during development of the brain. Metallothionein l and 2 expression is first detected by embryonic days E72–E73 (gestation is 150 days) at the mRNA level and the metallothionein protein is observed in cells of the proliferating ventricular zones. Subsequent expression is detected in radial glial cells, oligodendrocytes and astrocytes in several regions of the brain, most notably the cerebral cortex. In the adult brain, metallothionein is expressed in astrocytes but not in oligodendrocytes. Double-labelling immunohistochemistry using the glial fibrillary acidic protein (GFAP), an astrocyte marker, and metallothionein revealed that although there is an overlap in the profiles of the two proteins, there is no simple correlation in their expression. These observations are consistent with metallothionein, under physiological conditions, being regulated mainly by intracellular factors.     

Glial fibrillary acidic (GFA) protein in vertebrates: immunofluorescence and immunoblotting study with monoclonal and polyclonal antibodies

We report a comparative immunofluorescence and immunoblotting study of GFA protein, the subunit of glial filaments, in nonmammalian vertebrates. The study was conducted with polyclonal antibodies raised to human and shark antigen and with monoclonal antibodies isolated from mice immunized with chicken and bovine antigen. With the exception of cyclostomes, glial filaments appeared remarkably conserved in vertebrate phylogeny, both with respect to the molecular weight and immunoreactivity of their protein subunit. In most species, the antibodies decorated a single band in brain, spinal cord, and optic nerve extracts by the immunoblotting procedure. This band had the same molecular weight in the different CNS regions. With the exception of the turtle, species differences in the molecular weight of the band were not greater than those observed among mammalian vertebrates (human, bovine, and rat). However, there were some exceptional findings in fish. In goldfish and trout brain and spinal cord extracts, the antibodies decorated with the same intensity two bands. In accordance with previous immunofluorescence findings, goldfish optic nerve extracts were negative by the immunoblotting procedure. In four fishes (sea bass, tautog, trout, and scup), optic nerves reacted with the antibodies. However, the band decorated by the antibodies was higher in molecular weight than that obtained from brain and spinal cord extracts. Glial fibers were demonstrated by immunofluorescence in the brain, spinal cord, optic nerve, and retina of most species studied. In amphibia immunofluorescent structures were comparatively few, probably accounting for the negative results by immunoblotting. A comparative immunohistological study of the cerebellum showed the presence of perpendicular glial fibers in the molecular layer of most species examined. Birds and amphibia were different in this respect. Bergmann glia in chicken were GFA negative. In the frog and the toad, immunofluorescent fibers in the molecular layer of the cerebellum were haphazardly oriented. Ependymal radial glia was GFA-negative in the cerebellum of subavian vertebrates. Antisera raised in rabbit to shark GFA protein reacted with the same bovine GFA fragments recognized by polyclonal and monoclonal antibodies raised to human and bovine antigens, respectively, i.e., 30-kDa N-bromosuccinimide fragment (tryptophan cleavage); 35-kDa 2-nitro-5-thiocyanobenzoic acid fragment (cysteine cleavage); 18-kDa cyanogen bromide fragment (methionine cleavage). Conversely, the chicken GFA monoclonal antibodies selected for this study only reacted with noncleaved protein.     

Differentiation of radial glia from radial precursor cells and transformation into astrocytes in the developing rat spinal cord

Radial glial cell origins and functions have been studied extensively in the brain; however, questions remain relating to their origin and fate in the spinal cord. In the present study, radial glia are investigated in vivo using the neuroepithelial markers nestin and vimentin and the gliogenic markers GLAST, BLBP, 3CB2, and glial fibrillary acidic protein (GFAP). This has revealed heterogeneity among nestin/vimentin-positive precursor cells and suggests a lineage progression from neuroepithelial cell through to astrocyte in the developing spinal cord. A population of self-renewing radial cells, distinct from an earlier pseudo-stratified neuroepithelium, that resemble radial glial cells in morphology but do not express GLAST, BLBP, or 3CB2, is revealed. These radial cells arise directly from the spinal cord neuroepithelium and are probably the progenitors of neurons and the earliest appearing radial glial cells. GLAST/BLBP-positive radial glia first appear in the ventral cord at E14, and these cells gradually transform through one or more intermediate stages into differentiated astrocytes. Few if any neurons appear to be derived from radial glial cells, which are instead the major sources of astrocytes in the spinal cord. Evidence for the nonradial glial cell origins of some white matter astrocytes is also presented.     

Proliferation and differentiation of reactive nestin＋/GFAP＋ cells in an adult rat model of compression-induced spinal cord injury

BACKGROUND： Studies have demonstrated that astrocytes may possess similar properties to neural stem cells/neural precursor cells and have the potential to differentiate into neurons. OBJECTIVE： To observe neuroepithelial stem cell protein （nestin） and glial fibrillary acidic protein （GFAP） expression following spinal cord injury, and to explore whether nestin＋/GFAP＋ cells, which are detected at peak levels in gray and white matter around the ependymal region of the central canal in injured spinal cord, possess similar properties of neural stem cells. DESIGN, TIME AND SETTING： A randomized, controlled experiment. The study was performed at the Key Laboratory of Environment and Genes Related to Diseases （Xi＇an Jiaotong University）, Ministry of Education between January 2004 and December 2006. MATERIALS： Rabbit anti-rat nestin, β-tubulinⅢ, mouse anti-rat GFAP, galactocerebroside （GaLC） antibodies were utilized, as well as flow cytometry. METHODS： A total of 60 male, Sprague Dawley rats, aged 8 weeks, were randomly assigned to control （n = 12） and model （n = 48） groups. The spinal cord injury model was established in the model group by aneurysm clip compression, while the control animals were not treated. The gray and white matter around the ependymal region of the central canal exhibited peak expression of nestin＋/GFAP＋ cells. These cells were harvested and prepared into single cell suspension, followed by primary and passage cultures. The cells were incubated with serum-containing neural stem cell complete medium. MAINOUTCOME MEASURES： Nestin and GFAP expression in injured spinal cord was determined using immunohistochemistry and double-labeled immunofluorescence at 1, 3, 5, 7, 14, 28, and 56 days post-injury. In addition, cell proliferation and differentiation were detected using immunofluorescence cytochemistry and flow cytometry. RESULTS： Compared with the control group, the model group exhibited significantly increased nestin and GFAP expression （P 〈 0.05）, which reached peak levels between 3 and 7 days. The majority of cells in the ependymal region around the central canal were nestin＋/GFAP- cells, while the gray and white matter around the ependymal region were full of nestin＋/GFAP＋ cells, with an astrocytic-like appearance. A large number of nestin＋/GFAP＋cells were observed in the model group cell culture, and the cells formed clonal spheres and displayed strong nestin-positive immunofluorescence staining. Following induced differentiation, a large number of GaLC-nestin, β-tubulin Ⅲ-nestin, and GFAP-nestin positive cells were observed. However, no obvious changes were seen in the control group. Cells in S stage, as well as the percentage of proliferating cells, in the model group were significantly greater than in the control group （P 〈 0.01）, CONCLUSION： Spinal cord injury in the adult rat induced high expression of nestin＋/GFAP＋ in the gray and white matter around the ependymal region of the central canal. These nestin＋/GFAP＋ cells displayed the potential to self-renew and differentiate into various cells. The cells could be neural stem cells of the central nervous system.