星形胶质细胞与缺血性脑损伤

星形胶质细胞是脑中存在最多的细胞类型,能够为神经元提供代谢、营养支持及调节突触活性.脑缺血等病理状态下,反应性星形胶质细胞通过一系列生化过程的改变,诸如调节能量代谢、清除兴奋性氨基酸、抗氧化作用、分泌神经保护物质等发挥神经保护作用.缺血时星形胶质细胞内相关信号通路被激活,对细胞凋亡起调控作用.星形胶质细胞中相关酶、离子通道以及信号分子都可成为潜在的治疗靶点,通过药物干预,间接发挥神经保护作用.进一步阐明星形胶质细胞在缺血性脑损伤中的作用,可以为基于星形胶质细胞的新药研发提供思路.     

小胶质细胞与脑缺血关系的研究进展

小胶质细胞为脑内的主要免疫效应细胞, 参与一系列神经退行性疾病的发生。它的形态具有高度可塑性, 其形态学改变与其活化状态及生物学功能密切相关。脑缺血损伤后小胶质细胞发生活化, 且其活化受到精细调控。小胶质细胞在脑缺血损伤中发挥脑保护和神经毒性双相作用。因此, 深入研究小胶质细胞与脑缺血之间的关系, 以小胶质细胞的活化及调控作为出发点, 通过抑制小胶质细胞的过度活化、调控小胶质细胞表面或细胞内表达的受体或蛋白分子、拮抗小胶质细胞产生的神经毒性因子、促进小胶质细胞分泌神经保护性生物活性物质、阻断小胶质细胞介导的炎症反应等将为脑缺血的治疗提供新思路。本文对脑缺血损伤后, 小胶质细胞的活化及调控、效应及相关干预治疗等方面作一综述。     

半胱氨酰白三烯受体拮抗剂对脑缺血的保护作用

炎症是影响脑缺血急性损伤严重程度以及慢性期恢复的主要因素之一,而半胱氨酰白三烯是体内最重要的炎症介质之一,通过半胱氨酰白三烯受体(CysLT1R和CysLT2R)调节脑缺血后炎症等病变。目前,已证实CysLT1R拮抗剂对脑缺血动物模型急性和亚急性/慢性损伤的保护作用,其神经元保护作用可能是间接通过调节胶质细胞,对星形胶质细胞增殖及胶质疤痕形成则有明确的抑制作用。CysLT2R拮抗剂还有待深入研究,但可能与神经元和星形胶质细胞损伤、小胶质细胞激活等有密切关系。CysLT1R和Cys-LT2R拮抗剂是抗脑缺血损伤潜在的新型治疗药物。     

谷氨酸转运体靶点药物的抗脑缺血作用研究进展

兴奋性氨基酸毒性是脑缺血损伤的主要机制之一。缺血期间谷氨酸的大量累积会导致神经元细胞、星形胶质细胞等神经细胞发生兴奋性毒性损伤,因此对缺血期间谷氨酸水平的调控一直是脑缺血防治药物研究的重点。近年来研究表明,通过上调星形胶质细胞上谷氨酸转运体GLAST(EAAT1)和GLT-1(EAAT2)的表达或活性,增加缺血时谷氨酸的摄取,维持突触间隙内谷氨酸的正常浓度,从而降低兴奋性毒性,减轻缺血性脑损伤。一些化合物如β-内酰胺类抗生素、尿酸、甲状腺激素、雌激素、山楂酸等已在体内或体外实验中被证实对谷氨酸转运体的调节作用,对抗谷氨酸毒性,发挥神经保护作用。研究和开发以星形胶质细胞谷氨酸转运体为作用靶点的药物,为缺血性脑损伤的预防和治疗提供了一条新的途径。     

复方中药塞络通对多发性脑梗死大鼠星形胶质细胞功能及脂笼蛋白2蛋白表达的影响

目的脑卒中是一种常见的疾病,绝大多数脑卒中病例是由短暂性或永久性脑血管闭塞引起的缺血性脑血管病(缺血性中风)最终导致脑梗死。星形胶质细胞做为脑内大量存在的细胞,在缺血损伤后形态肥大,表现为突起延长和胞体肿胀。脂笼蛋白2(LCN2)是一种分泌蛋白,在脑缺血和神经退行性疾病中具有重要作用。塞络通胶囊(SLT)是由人参、银杏、藏红花三种中草药组成的治疗血管性痴呆的标准化制剂。虽然最近的临床试验已经证明SLT对血管性痴呆的有益作用,但其潜在的细胞机制尚未得到充分的探索。方法采用大鼠微球法致多发性脑梗死实验模型,通过Morris水迷宫实验评价SLT对恢复期大鼠空间记忆功能障碍的影响;随后,根据组织内及血清内炎性因子的表达,以及qPCR、免疫荧光、免疫印迹观察星形胶质细胞的活化、特异蛋白LCN2及其诱导的JAK2\STAT3信号通路的变化,以考察恢复期脑缺血损伤后星形胶质细胞的活化与炎性反应的关系及SLT对恢复期缺血损伤皮层区星形胶质细胞功能的影响;建立人星形胶质细胞糖氧诱导(OGD)损伤模型,并采用慢病毒转染的方法过表达目的基因LCN2,检测细胞分泌炎性因子含量变化,免疫荧光、蛋白免疫印迹观察星形胶质细胞的活化、特异蛋白LCN2及其诱导的JAK2/STAT3信号通路的变化,考察星形胶质细胞损伤后SLT有效成分对其的影响。结果 SLT可显著降低脑缺血引起的大鼠空间记忆认知功能障碍,减轻星形胶质细胞的活化及增殖,较为明显改善脑脑缺血损伤大鼠皮层缺血周边半暗带区神经元及突触超微结构损伤;SLT可抑制缺血侧皮层区及血清内炎性因子及趋化因子的表达,根据免疫荧光与免疫印迹的结果看出,SLT可能通过抑制LCN2诱导的JAK2/STAT3信号通路的表达来抑制炎性反应。结论 SLT介导神经炎症反应,通过LCN2-JAK2/STAT3通路抑制星形胶质细胞增生,抑制神经炎症反应,从而保护缺血性脑损伤,为缺血性脑卒中的治疗策略提供新的思路。     

星形胶质细胞的免疫炎性反应和谷氨酸代谢异常在卒中后抑郁发病中的作用

星形胶质细胞是人脑内数量最多的细胞,在缺血早期结构会发生明显变化,表达多种神经营养因子和损伤因子。卒中发生后,星形胶质细胞活化为反应性星形胶质细胞,通过神经保护或神经毒性作用影响组织修复和神经炎性疾病的发生和发展。卒中诱发细胞间谷氨酸浓度及炎性因子的增加会促进卒中后抑郁发生,而卒中后活化的星形胶质细胞会通过多条通路调控免疫炎性反应和神经元谷氨酸代谢。现就星形胶质细胞介导的免疫炎性反应与谷氨酸能系统对卒中后抑郁中发生发展信号通路做进一步剖析,以期提供靶向调控星形胶质细胞调节谷氨酸及炎性因子水平策略,为治疗卒中后抑郁提供思路和线索。     

神经血管单元结构和功能及其在脑缺血损伤发生机制中的作用

近年来,从神经血管单元（NVU）这一整体性结构及其功能出发开展脑缺血发病机制的研究越来越受到人们的重视,NVU已经成为脑科学和脑重大疾病研究领域的热点之一。NVU主要组成细胞有神经元、星形胶质细胞、小胶质细胞和脑微血管内皮细胞等,它们在结构上密切相关,在功能上共同维持脑稳态,在脑功能和脑缺血损伤中发挥重要作用。NVU损伤导致微血管及血脑屏障完整性受损、神经元细胞死亡、神经胶质反应、免疫细胞浸润,甚至组织损伤和脑水肿。本文以期阐明NVU的结构和功能及其在脑缺血损伤发生机制中的作用,为开展基于NVU结构和功能的脑缺血疾病防治药物研究提供新思路和新策略。     

钩藤碱对缺血再灌注诱导大鼠星形胶质细胞损伤的作用

目的:以原代培养的大鼠大脑星形胶质细胞进行缺血再灌注损伤处理,观察钩藤碱(Rsy)对星形胶质细胞损伤的保护作用.方法:1～3 d龄SD大鼠乳鼠大脑星形胶质细胞原代培养,含连二亚硫酸钠的无糖Earle's液进行缺血缺氧处理造模,MTT法测定细胞存活率,Hoechst 33258荧光显微镜观察细胞形态学变化,流式细胞仪检测细胞坏死、凋亡率,用LDH试剂盒测定LDH漏出率.结果:与模型组比较,钩藤碱0.02、0.2 mg·mL-1均能显著提高细胞存活率,显著降低细胞坏死率和细胞凋亡率,也能显著降低细胞LDH漏出率.结论:钩藤碱对缺血再灌注损伤后星形胶质细胞的坏死凋亡具有显著抑制作用,提示钩藤碱可能通过抑制星形胶质细胞凋亡和坏死而对脑缺血损伤产生保护作用.     

右美托咪定预处理对局灶性脑缺血/再灌注星形胶质细胞胶质纤维酸性蛋白表达的影响

目的 探讨预注右美托咪定对局灶性脑缺血/再灌注后星形胶质细胞胶质纤维酸性蛋白(glial fibrillary acidic protein,GFAP)表达的影响。方法 大脑中动脉插线法制作大鼠局灶性脑缺血/再灌注模型。观察脑缺血2 h再灌注24 h后神经功能损害改变并评分,并采用免疫组化和蛋白免疫印迹方法观察大鼠脑缺血后星形胶质细胞GFAP蛋白表达情况。结果 缺血/再灌注后可诱导大鼠脑组织星形胶质细胞GFAP表达明显增强,右美托咪定可明显改善大鼠神经功能损害,减少缺血区GFAP阳性星型胶质细胞,降低GFAP表达水平。结论 早期应用右美托咪定可抑制脑缺血后星形胶质细胞GFAP的过度表达,可发挥抗脑缺血损伤,保护神经元作用。     

脑缺血后活化星形胶质细胞所致损伤因子的探讨

脑缺血损伤时,活化星形胶质细胞产生一系列细胞因子,其中一氧化氮、内皮素、磷脂酶A2、肿瘤坏死因子等通过各种机制对缺血后神经细胞产生毒性作用,引起神经细胞坏死、凋亡。深入了解活化星形胶质细胞对缺血性神经细胞损伤的作用机制,对脑缺血的治疗具有重要意义。     

Glycans and glycan-binding proteins in brain: galectin-1-induced expression of neurotrophic factors in astrocytes

Astrocytes are a major cell type in the central nervous system (CNS). They are considered to act in cooperation with neurons and other glial cells and to participate in the development and maintenance of functions of the CNS. Immature astrocytes possess a polygonal shape and have no processes, and continue to proliferate, while mature astrocytes have a stellate cell morphology, increased glial fibrillary acidic protein expression, and proliferate slowly. Stellate astrocytes, which immediately appear at the site of brain lesions by ischemia or other brain injuries, are thought to produce several neurotrophic factors to protect neurons from delayed post-lesion death. Previously we reported that galectin-1, a member of the family of beta-galactoside-binding proteins, induced astrocyte differentiation, and the differentiated astrocytes greatly enhanced their production of brain-derived neurotrophic factor (BDNF). BDNF is known to promote neuronal survival, guide axonal pathfinding, and participate in activity-dependent synaptic plasticity during development. The effect of galectin-1 is astrocyte-specific and does not have any effect on neurons. Prevention of neuronal loss during CNS injuries is important to maintain brain function. Induction of neuroprotective factors in astrocytes by an endogenous mammalian lectin may be a new mechanism for preventing neuronal loss after brain injury, and may be useful for the treatment of neurodegenerative disorders.     

Immunophilin ligands decrease release of pro-inflammatory cytokines (IL-1beta, TNF-alpha and IL-2 in rat astrocyte cultures exposed to simulated ischemia in vitro

The aim of present study was to evaluate the effects of immunophilin ligands (cyclosporin A, FK506 and rapamycin) on the simulated ischemia-induced release of pro-inflammatory cytokines (IL-1beta, TNF-alpha and IL-2) in rat primary astrocyte cell cultures. Astrocytes were exposed to cyclosporin A (CsA) (0.25, 0.5, 1, 10, 20 and 50 microM), FK506 (1, 10, 100, 1000 nM) and rapamycin (10, 100, 500 and 1000 nM). In vitro simulated ischemia significantly increased secretion of IL-1beta, TNF-alpha and IL-2 by astrocyte cultures deprived of microglia (by shaking and incubating with L-leucine methyl ester). CsA (at concentrations of 10-50 microM), FK506 (at all used concentrations) and rapamycin (in dose-dependent manner) significantly attenuated IL-1beta release after 24 h exposure to ischemic conditions. Immunophilin ligands at all used concentrations significantly decreased TNF-alpha levels in culture media after 24 h exposure to ischemia. Moreover, significant decrease in IL-2 secretion at 0.25, 0.5, 1 and 50 microM CsA and FK506 at concentrations of 100 and 1000 nM were observed. The results suggest that immunophilin ligands may regulate glial activity during ischemia by affecting the release of pro-inflammatory cytokines.     

Expression and Activity of the Na-K ATPase in Ischemic Injury of Primary Cultured Astrocytes

Astrocytes are reported to have critical functions in ischemic brain injury including protective effects against ischemia-induced neuronal dysfunction. Na-K ATPase maintains ionic gradients in astrocytes and is suggested as an indicator of ischemic injury in glial cells. Here, we examined the role of the Na-K ATPase in the pathologic process of ischemic injury of primary cultured astrocytes. Chemical ischemia was induced by sodium azide and glucose deprivation. Lactate dehydrogenase assays showed that the cytotoxic effect of chemical ischemia on astrocytes began to appear at 2 h of ischemia. The expression of Na-K ATPase α1 subunit protein was increased at 2 h of chemical ischemia and was decreased at 6 h of ischemia, whereas the expression of α1 subunit mRNA was not changed by chemical ischemia. Na-K ATPase activity was time-dependently decreased at 1, 3, and 6 h of chemical ischemia, whereas the enzyme activity was temporarily recovered to the control value at 2 h of chemical ischemia. Cytotoxicity at 2 h of chemical ischemia was significantly blocked by reoxygenation for 24 h following ischemia. Reoxygenation following chemical ischemia for 1 h significantly increased the activity of the Na-K ATPase, while reoxygenation following ischemia for 2 h slightly decreased the enzyme activity. These results suggest that the critical time for ischemia-induced cytotoxicity of astrocytes might be 2 h after the initiation of ischemic insult and that the increase in the expression and activity of the Na-K ATPase might play a protective role during ischemic injury of astrocytes.     

星形胶质细胞功能异常诱发癫痫机制的研究进展

癫痫是一种由于大脑神经元异常同步放电引起的脑功能障碍综合征,发病机制迄今尚未完全阐明。近年来越来越多的实验与临床研究显示,星形胶质细胞在癫痫的病理过程中起到了重要作用,有可能成为药物干预癫痫的新靶点。该文综述了星形胶质细胞由于功能以及与神经元之间信号调控异常从而诱发癫痫的分子机制的研究进展。     

Evaluation of L-glutamate clearance capacity of cultured rat cortical astrocytes

Astrocytes have a function in the uptake of excitatory neurotransmitter L-glutamate via the glutamate transporter. To evaluate the L-glutamate clearance capacity of astrocytes, we developed a colorimetric method for the determination of L-glutamate concentration and measured changes in extracellular L-glutamate concentration in rat cortical astrocyte cultures. When L-glutamate (50-200 microM) was added to astrocyte cultures and incubated for 1-8 h, the extracellular L-glutamate concentration declined with time. When L-glutamate was mixed with astrocyte culture supernatants only, no significant change in L-glutamate concentration was observed, ruling out the possibility that L-glutamate is spontaneously or enzymatically degraded in the extracellular space. Alternatively, the time-dependent decline of extracellular L-glutamate concentration was blocked by the presence of glutamate uptake inhibitors, indicating that the glutamate uptake system of astrocytes plays a major role in the clearance of extracellular L-glutamate.     

Resveratrol increases antioxidant defenses and decreases proinflammatory cytokines in hippocampal astrocyte cultures from newborn,adult and aged Wistar rats

Astrocytes are responsible for modulating neurotransmitter systems and synaptic information processing, ionic homeostasis, energy metabolism, maintenance of the blood–brain barrier, and antioxidant and inflammatory responses. Our group recently published a culture model of cortical astrocytes obtained from adult Wistar rats. In this study, we established an in vitro model for hippocampal astrocyte cultures from adult (90 days old) and aged (180 days old) Wistar rats. Resveratrol, a polyphenol found in grapes and red wine, exhibits antioxidant, anti-inflammatory, anti-aging and neuroprotective effects that modulate glial functions. Here, we evaluated the effects of resveratrol on GSH content, GS activity, TNF-α and IL-1β levels in hippocampal astrocytes from newborn, adult and aged Wistar rats. We observed a decrease in antioxidant defenses and an increase in the inflammatory response in hippocampal astrocytes from adult and aged rats compared to classical astrocyte cultures from newborn rats. Resveratrol prevented these effects. These findings reinforce the neuroprotective effects of resveratrol, which are mainly associated with antioxidant and anti-inflammatory activities.     

TGF-β1-Samd3信号转导在星形胶质细胞增殖中的作用

目的探讨TGF-β1对体外培养的星形胶质细胞增殖的影响及其Smad3信号转导机制。方法体外培养的原代星形胶质细胞,传代接种后采用SiRNA基因沉默技术,干扰Smad3基因的表达,RT-PCR验证沉默效果,应用免疫荧光技术观察干扰TGF-β1-Smad3通路后对星形胶质细胞增殖的影响。结果 TGF-β1对星形胶质细胞增殖有明显促进作用,并呈现一定的剂量依赖性;成功沉默Smad3基因后,星形胶质细胞的增殖率明显减低;成功沉默Smad3基因能干扰TGF-β1对星形胶质细胞增殖的促进作用。结论 TGF-β1-Smad3信号转导通路对星形胶质细胞增殖起调节作用。