高压氧对急性CO 中毒大鼠脑内源性神经干细胞的影响

目的:探讨高压氧对急性CO中毒大鼠脑内源性神经干细胞的影响,分析HBO治疗急性CO中毒脑损伤的机制。方法:建立急性CO中毒大鼠模型,给予高压氧(HBO)治疗后,H-E染色观察大鼠脑组织病理学变化,免疫组织化学方法检测大鼠脑内神经干细胞(nestin)和星形胶质细胞(GFAP)的表达。结果:H-E染色标本上,对照组脑内神经元形态正常,染毒组脑皮质出现大量变性坏死细胞,海马锥体细胞层稀疏,HBO组坏死细胞明显减少。免疫组化结果显示对照组nestin和GFAP表达数量形态均正常,染毒组nestin表达增加,但无统计学意义,GFAP形态数量发生改变,HBO组nestin表达明显增加,且在大脑皮层可见部分nestin阳性细胞和nestin-GFAP双阳性细胞;GFAP表达趋于正常。结论:急性CO中毒作为脑损伤因素可轻度激活大鼠脑内源性神经干细胞,并使星形胶质细胞增生变形、神经元变性坏死,HBO治疗可减轻星形胶质细胞损伤,明显激活内源性神经干细胞,并促使其增殖、迁移和分化。提示HBO可能通过激活神经干细胞起治疗作用。     

创伤性脑损伤后IL-1?茁在神经胶质细胞中经时定位表达的研究*

目的:探讨创伤性脑损伤(TBI)后白细胞介素-1β(IL-1β)在神经胶质细胞中的经时定位表达情况。方法:选择72只SPF级雄性小鼠分为假手术组(sham组)、TBI 6h组、TBI 12h组、TBI 1d组、TBI 4d组与TBI 7d组,每组12只,分别在脑损伤后6h、12h、1d、4d、7d时获取血清和脑组织并且制作切片。ELISA检测损伤后炎症因子IL-1β、白细胞介素-6 (IL-6)和肿瘤坏死因子-α(TNF-α)的表达。Western blot检测钙离子结合蛋白-1(IBA-1)和胶质纤维酸性蛋白(GFAP)的表达。应用免疫荧光双重染色技术观察炎症因子IL-1β在小胶质细胞和星形胶质细胞中的定位表达情况。结果:TBI后6h-7d时炎症因子IL-1β、IL-6和TNF-α的表达量均高于sham组(P0.05)。Western blot结果显示,IBA-1的表达在损伤后6h-7d时高于sham组,GFAP的表达在损伤后1d-7d时高于sham组(P0.05)。免疫荧光双重染色技术显示,6h、12h时IL-1β主要表达在小胶质细胞中,IL-1β和IBA-1共表达细胞数量多于sham组(P0.05);1d、4d、7d时IL-1β主要表达在星形胶质细胞中,IL-1β和GFAP共表达细胞数量多于sham组(P0.05)。结论:TBI诱导了胶质细胞和炎症因子的表达,其表达随脑损伤的时间而变化,IL-1β早期定位表达于小胶质细胞,后期定位表达于星形胶质细胞中。     

急性酒精中毒合并中度创伤性脑损伤大鼠海马GFAP的表达

目的:观察急性酒精中毒合并中度创伤性脑损伤后大鼠海马星形胶质细胞标记物胶质纤维酸性蛋白(GFAP)表达的变化.方法:健康成年雄性SD大鼠72只,随即机分为4组:假手术组(N组)、急性酒精中毒组(E组)、中度创伤性脑损伤组(T组)和急性酒精中毒合并中度创伤性脑损伤组(E T组).腹腔注射酒精(2.5g/kg)致使大鼠急性酒精中毒,2h后,按改进的Feeney's自由落体硬膜外撞击方法使其合并中度创伤性脑损伤(600g.cm).各组动物术后6h、24h和48h处死.中性红染色观察海马CA1区神经元形态学改变;用免疫组织化学的方法检测海马CA1区GFAP表达变化.结果:与N组和E组相比,T组和E T组GFAP表达显著增多(P＜0.01).术后6h和24h,T组GFAP表达显著高于E T组(P＜0.05);T组和E T组的海马CA1区神经元细胞出现胞体肿胀,排列散乱,但T组上述形态学改变较E T组明显.结论:急性酒精中毒合并中度创伤性脑损伤的早期可通过减少GFAP的表达,抑制星形胶质细胞激活,减少炎症反应发挥保护作用.     

LPS诱导海马星形胶质细胞活化与活化的星形胶质细胞对海马神经元的影响

探讨脂多糖(Lipopolysaccharide,LPS)对长时间存活大鼠海马内星形胶质细胞的反应以及对神经元的影响。方法:本实验用10只健康成年雄性SD大鼠,海马CA3区注射LPS 10μ1．7和14d后,尼氏染色观察神经元的变化,免疫组织化学染色结合图像分析方法观察海马CA3区注射部位胶质纤维酸性蛋白(glial fibrillary acidic protein GFAP)、的表达变化。结果:脂多糖可促进海马星形胶质细胞的活化,但并不能引起海马区神经元的损伤。结论:星形胶质细胞在脑损伤后的脑内炎症反应起了一定的作用,但并不能引起神经元的损伤。     

二十五味珊瑚丸对D-半乳糖衰老鼠海马细胞形态和GFAP表达的影响

探讨二十五味珊瑚丸对D-半乳糖衰老模型大鼠海马锥体细胞形态和星形胶质细胞胶质纤维酸性蛋白(GFAP)表达的影响。采用颈背部皮下注射D-半乳糖制作大鼠衰老模型。于造模的第6周,给予二十五味珊瑚灌胃。之后取各组脑组织进行HE染色、GFAP免疫组化染色以及Western blotting。与模型组比较,二十五味珊瑚丸组大鼠海马CA3区锥体细胞层细胞丢失较少,细胞排列较紧密、整齐;DG区GFAP阳性的星形胶质细胞数量减少,胞体较小,突起较细;海马GFAP表达下降,差异有显著性(P0.05)。D-半乳糖衰老模型大鼠海马锥体细胞衰老变性且GFAP的表达增多;二十五味珊瑚丸可抑制D-半乳糖衰老模型大鼠海马锥体细胞的衰老变性和星形胶质细胞GFAP的表达。     

高压氧疗法对创伤性脑损伤大鼠氧化应激指标及促／抗炎细胞因子水平的影响

目的：研究高压氧（HBO）疗法对创伤性脑损伤（TBI）大鼠氧化应激指标及促／抗炎细胞因子水平的影响方法：SD雄性大鼠18只,随机分为3组（n=6）：假手术组、损伤对照组和HBO治疗组采用Feency法建立大鼠TBI模型,假手术组只开放骨面,不予打击HBO治疗组大鼠于脑损伤后6h采用动物高压舱,以3ATA压力纯氧治疗60min。所有动物于手术后24h处死,分离脑组织,取伤侧脑半球行组织匀浆,分别测定匀浆上清液中超氧化物歧化酶（SOD）、丙二醛（MDA）、NO的含量以及促炎细胞因子TNF-α、IL-6、IL-1β及抗炎细胞因子IL-10的水平,结果：与损伤对照组相比,HBO治疗使SOD、NO以及IL-10水平升高,同时降低脑内MDA及TNF-α、IL-6、IL-1β的含量结论：HBO治疗可抑制TBI后自由基的生成,从而减轻脂质过氧化反应;同时,HBO治疗可减少促炎细胞因子的生成,促进抗炎细胞因子的产生,从而可减轻损伤脑组织的炎症反应,有助于减轻TBI后脑组织的继发性损伤.     

天冬酰胺内肽酶和胶质细胞在创伤性脑损伤中的激活

摘要 目的：创伤性脑损伤（traumatic brain injury, TBI）缺乏安全有效的治疗手段,亟须寻找新的干预靶点。天冬酰胺内肽酶 (asparaginyl endopeptidase, AEP)在免疫和神经系统疾病中起重要作用,本研究观察了小鼠TBI模型中AEP的激活和变化,探讨AEP对脑损伤和修复的意义。方法：控制性皮层撞击法在小鼠右脑半球制作TBI损伤,在造模后的不同时间点,测定受损脑组织内的乳酸含量和AEP的活性变化,免疫荧光化学染色观察TBI之后3天的胶质细胞活化,以及AEP在其中的表达。结果：TBI造成乳酸在受损脑组织内逐渐堆积,导致小胶质细胞和星形胶质细胞的反应性活化和增生,AEP的上调和激活出现在TBI的继发性脑损伤阶段,AEP在小胶质细胞和星形胶质细胞内均出现上调。结论：AEP有可能参与调控TBI引发的胶质细胞活化,在神经损伤和修复中发挥重要作用。     

大鼠局灶性脑缺血后星形胶质细胞过度增殖对局部微循环的影响

目的 观察局灶性脑缺血后海马和缺血边缘区星形胶质细胞过度增殖对微循环的影响。方法将大鼠随机分为假手术组、缺血组和干预组,缺血组和干预组采用线栓法制备大脑中动脉栓塞模型,缺血组侧脑室采用ALZET微渗透泵给予0．2％DMSO,干预组给予细胞周期抑制剂roscovitine,假手术组不插入线栓,不给与任何药物干预。缺血7d后于股静脉注入FITC标记的葡聚糖标记血管,小鼠抗大鼠单克隆抗胶质纤维酸性蛋白（glial fibrillary acidic protein,GFAP）抗体标记星形胶质细胞;激光共聚焦三维成像显示胶质细胞于微循环之间的关系。结果缺血同侧海马和缺血边缘区在GFAP阳性细胞增多的同时,局部微血管血流灌注明显减少,应用细胞周期抑制剂roscovitine抑制星形胶质细胞增生可以明显增加局部微血管的血流灌注。结论脑缺血后缺血边缘区和海马的反应性星形胶质细胞增生与微循环灌注减少密切相关。     

电针对脊髓损伤星形胶质细胞增生及其NGF表达的影响

目的研究脊髓损伤后电针治疗对星形胶质细胞增生及其内源性神经生长因子(nerve growth factor,NGF)表达的影响.方法选用成年雌性Wistar大鼠,随机分为3组.A组为正常对照组,B组、C组为下胸段脊髓不完全损伤.B组损伤后不治疗,C组损伤后给予督脉电针治疗.损伤后3 d、1 、2或4周应用免疫组化染色分别观察损伤脊髓胶质原纤维酸性蛋白(glial fibroblast acid protein,GFAP)和NGF表达的变化.结果 B组术后3 d,GFAP阳性细胞明显增多, 2周后开始减少,4周时仍有较多的阳性细胞;C组GFAP阳性细胞明显少于B组,1周时达高峰.脊髓损伤后NGF表达呈逐渐增加的趋势.C组NGF的表达明显高于B组,且一直保持在较高水平.NGF阳性细胞大部分与GFAP阳性细胞形态相似.结论电针治疗能减少星形胶质细胞增生,促进内源性NGF的合成,从而创造了有利于神经再生的微环境.     

正加速度暴露对大鼠海马星形胶质细胞GFAP表达的影响

目的探讨正加速度( Gz)重复暴露后不同时间海马星形胶质细胞GFAP表达的变化.方法 SD大鼠60只,随机分成对照组、 Gz重复暴露后1h、6h、12h、24h和48h组,每组10只.采用动物离心机,建立 Gz引发急性脑缺血模型;应用免疫组织化学技术,分别检测 Gz重复暴露后不同时间,海马星形胶质细胞GFAP的表达状况.结果海马星形胶质细胞GFAP阳性细胞数,在 Gz暴露后1h即显著增加,于12h达到高峰,而后逐渐下降,48h仍维持在较高水平,实验组与对照组比较,有显著性差异.结论 Gz重复暴露导致海马星形胶质细胞GFAP表达上调,可能对神经元的缺血损伤起保护作用.     

Toll-Like Receptor 4 Knockdown Attenuates Brain Damage and Neuroinflammation After Traumatic Brain Injury via Inhibiting Neuronal Autophagy and Astrocyte Activation

Toll-like receptor 4 (TLR4) has been linked to various pathophysiological conditions, such as traumatic brain injury (TBI). It is reported that posttraumatic neuroinflammation is an essential event in the progression of brain injury after TBI. Recent evidences indicate that TLR4 mediates glial phagocytic activity and inflammatory cytokines production. Thus, TLR4 may be an important therapeutic target for neuroinflammatory injury post-TBI. This study was designed to explore potential effects and underlying mechanisms of TLR4 in rats suffered from TBI. TBI model was induced using a controlled cortical impact in rats, and application of TLR4 shRNA silenced TLR4 expression in brain prior to TBI induction. Elevated TLR4 was specifically observed in the hippocampal astrocytes and neurons posttrauma. Interestingly, TLR4 shRNA decreased the concentrations of interleukin (IL)-1β, IL-6, and tissue necrosis factor-α; alleviated hippocampal neuronal damage; reduced brain edema formation; and improved neurological deficits after TBI. Meanwhile, to further explore underlying molecular mechanisms of this neuroprotective effects of TLR4 knockdown, our results showed that TLR4 knockdown significantly inhibited the upregulation of autophagy-associated proteins caused by TBI. More importantly, an autophagy inducer, rapamycin pretreated, could partially abolish neuroprotective effects of TLR4 knockdown on TBI rats. Furthermore, TLR4 silencing markedly suppressed GFAP upregulation and improved cell hypertrophy to attenuate TBI-induced astrocyte activation. Taken together, these findings suggested that TLR4 knockdown ameliorated neuroinflammatory response and brain injury after TBI through suppressing autophagy induction and astrocyte activation.     

高压氧预处理对大鼠脑缺血再灌注损伤的保护作用及对其海马BDNF和GDNF基因表达的影响

目的:探讨高压氧预处理(Hyperbaric oxygen preconditioning, HBO-PC)对大鼠脑缺血再灌注损伤的保护作用及对其海马脑源性神经营养因子(brain-derived neurotrophic factor, BDNF)、胶质细胞源性神经营养因子(glialcellline-derivedneurotrophicfactor,GDNF)基因表达的影响。方法:将32只SD雄性大鼠随机分为对照组(Sham组)、高压氧对照组(HBO组)、模型组(MCAO组)、高压氧预处理+模型组(HBO+MCAO组),对HBO组和HBO+MCAO组连续给予高压氧预处理5天,随后对MCAO组和HBO+MCAO组进行右侧颈内动脉栓线术,建立大脑中动脉闭塞(middle cerebral artery occlusion, MCAO)模型,其他两组行假手术,于术后第7天对各组大鼠进行Morris水迷宫行为学检测和神经功能评分,检测结束后处死大鼠,进行神经功能缺损评分及氯化三苯基四氮唑(2,3,5-triphenyltetrazolium chloride, TTC)染色;通过蛋白免疫印迹法(Western Blot)检测大鼠海马组织BDNF和GDNF的基因表达情况。结果:(1)神经功能评分提示:Sham组和HBO组均未出现神经功能障碍,MCAO组大鼠出现明显的神经功能障碍,MCAO+HBO组神经功能评分明显高于MCAO组(P0.05)。(2)TTC检测提示:Sham组和HBO组脑组织损伤一侧均未出现梗死灶,MCAO组出现较大的梗死面积比(25.45±8.75)%,MCAO+HBO组的梗死面积比(18.84±10.55)显著小于MCAO组,差异具有统计学意义(P 0.05)。(3)Western Blot检测显示:MCAO组BDNF与GDNF基因表达水平显著低于Sham组和HBO组,差异具有统计学意义(P 0.05),而MCAO+HBO组可以逆转这一效应,差异具有统计学意义(P 0.05)。结论:高压氧预处理可以通过调节BDNF、GDNF基因表达,改善MCAO模型大鼠神经功能和认知水平,发挥神经保护作用。     

A Culture Model of Reactive Astrocytes: Increased Nerve Growth Factor Synthesis and Reexpression of Cytokine Responsiveness

Abstract: Reactive gliosis, which occurs in response to damage to the central nervous system, has been recognized for years but is not yet understood. We describe here a tissue culture model of reactive astrocytes used to characterize their properties. Cultures are prepared 1 week following 6-hydroxydopamine (6-OHDA) lesion of rat substantia nigra and compared with astrocytes cultured from normal adult rats or rats injected with saline only. Astrocytes from the 6-OHDA-lesioned side contained elevated levels of glial fibrillary acidic protein (GFAP) and GFAP mRNA and were intensely immunoreactive for GFAP, vimentin, and two epitopes that in vivo are found only on reactive astrocytes. The basal content of nerve growth factor (NGF) mRNA and NGF in astrocytes from 6-OHDA-lesioned rats was significantly higher relative to control astrocytes. Two inflammatory cytokines, interleukin-1β and interferon-γ, increased synthesis of NGF up to 20-fold in the reactive cells, whereas there was no response in the normal adult astrocytes. Astrocytes from postnatal day 2 rats shared many of the properties of the reactive adult astrocytes. These cultures offer the possibility to characterize the cellular and molecular properties of reactive astrocytes and to determine the factors responsible for activation of astrocytes.     

Expression of Dixdc1 and its Role in Astrocyte Proliferation after Traumatic Brain Injury

DIX domain containing 1 (Dixdc1), a positive regulator of Wnt signaling pathway, is recently reported to play a role in the neurogenesis. However, the distribution and function of Dixdc1 in the central nervous system (CNS) after brain injury are still unclear. We used an acute traumatic brain injury (TBI) model in adult rats to investigate whether Dixdc1 is involved in CNS injury and repair. Western blot analysis and immunohistochemistry showed a time-dependent up-regulation of Dixdc1 expression in ipsilateral cortex after TBI. Double immunofluorescent staining indicated a colocalization of Dixdc1 with astrocytes and neurons. Moreover, we detected a colocalization of Ki-67, a cell proliferation marker with GFAP and Dixdc1 after TBI. In primary cultured astrocytes stimulated with lipopolysaccharide, we found enhanced expression of Dixdc1 in parallel with up-regulation of Ki-67 and cyclin A, another cell proliferation marker. In addition, knockdown of Dixdc1 expression in primary astrocytes with Dixdc1-specific siRNA transfection induced G0/G1 arrest of cell cycle and significantly decreased cell proliferation. In conclusion, all these data suggest that up-regulation of Dixdc1 protein expression is potentially involved in astrocyte proliferation after traumatic brain injury in the rat.     

Reactive Transformation and Increased BDNF Signaling by Hippocampal Astrocytes in Response to MK-801

MK-801, also known as dizocilpine, is a noncompetitive N-methyl-D-aspartic acid (NMDA) receptor antagonist that induces schizophrenia-like symptoms. While astrocytes have been implicated in the pathophysiology of psychiatric disorders, including schizophrenia, astrocytic responses to MK-801 and their significance to schizotypic symptoms are unclear. Changes in the expression levels of glial fibrillary acid protein (GFAP), a marker of astrocyte activation in response to a variety of pathogenic stimuli, were examined in the hippocampus of rats treated with the repeated MK-801 injection (0.5 mg/10ml/kg body weight for 6 days) and in primary cultured hippocampal astrocytes incubated with MK-801 (5 or 20 μM for 24 h). Moreover, the expression levels of BDNF and its receptors TrkB and p75 were examined in MK-801-treated astrocyte cultures. MK-801 treatment enhanced GFAP expression in the rat hippocampus and also increased the levels of GFAP protein and mRNA in hippocampal astrocytes in vitro. Treatment of cultured hippocampal astrocytes with MK-801 enhanced protein and mRNA levels of BDNF, TrkB, and p75. Collectively, our results suggest that hippocampal astrocytes may contribute to the pathophysiology of schizophrenia symptoms associated with NMDA receptor hypofunction by reactive transformation and altered BDNF signaling.     

Disrupted glial fibrillary acidic protein network in astrocytes from vimentin knockout mice

Glial fibrillary acidic protein (GFAP) is an intermediate filament protein expressed predominantly in astrocytes. The study of its expression in the astrocyte lineage during development and in reactive astrocytes has revealed an intricate relationship with the expression of vimentin, another intermediate filament protein widely expressed in embryonic development. these findings suggested that vimentin could be implicated in the organization of the GFAP network. To address this question, we have examined GFAP expression and network formation in the recently generated vimentin knockout (Vim-) mice. We show that the GFAP network is disrupted in astrocytes that normally coexpress vimentin and GFAP, e.g., those of the corpus callosum or the Bergmann glia of cerebellum. Furthermore, Western blot analysis of GFAP protein content in the cerebellum suggests that posttranslational mechanisms are implicated in the disturbance of GFAP network formation. The role of vimentin in this process was further suggested by transfection of Vim- cultured astrocytes with a vimentin cDNA, which resulted in the normal assembly of the GFAP network. Finally, we examined GFAP expression after stab wound-induced astrogliosis. We demonstrate that in Vim- mice, reactive astrocytes that normally express both GFAP and vimentin do not exhibit GFAP immunoreactivity, whereas those that normally express GFAP only retain GFAP immunoreactivity. Taken together, these results show that in astrocytes, where vimentin is normally expressed with GFAP fails to assemble into a filamentous network in the absence of vimentin. In these cells, therefore, vimentin appears necessary to stabilize GFAP filaments and consequently the network formation.     

Diabetes Inhibits Cerebral Ischemia-Induced Astrocyte Activation - an Observation in the Cingulate Cortex

The objective of this study was to study the effect of diabetic hyperglycemia on astrocytes after forebrain ischemia. Streptozotocin (STZ)-injected hyperglycemic and vehicle-injected normoglycemic rats were subjected to 15 minutes of forebrain ischemia. The brains were harvested in sham-operated controls and in animals with 1 and 6 h of recirculation following ischemia. Brain damage was accessed by haematoxylin and eosin (H&E) staining, cleaved caspase-3 immunohistochemistry and TdT-mediated-dUTP nick end labeling (TUNEL). Anti-GFAP antibody was employed to study astrocytes. The results showed that the 15-minute ischemia caused neuronal death after 1 and 6 h of reperfusion as revealed by increased numbers of karyopyknotic cells, edema, TUNEL-positive and active caspase-3-positive cells. Ischemia also activated astrocytes in the cingulated cortex as reflected by astrocyte stomata hypertrophy, elongated dendrites and increases in the number of dendrites, and immunoreactivity of GFAP. Diabetic hyperglycemia further enhanced neuronal death and suppressed ischemia-induced astrocyte activation. Further, diabetes-damaged astrocytes have increased withdrawal of the astrocyte end-foot from the cerebral blood vessel wall. It is concluded that diabetes-induced suppression and damages to astrocytes may contribute to its detrimental effects on recovery from cerebral ischemia.     

Triptolide Upregulates NGF Synthesis in Rat Astrocyte Cultures

Triptolide (T10), an extract from the traditional Chinese herb, Tripterygium wilfordii Hook F (TWHF), has been shown to attenuate the rotational behavior induced by d-amphetamine and prevent the loss of dopaminergic neurons in the substantia nigra in rat models of Parkinson’s disease. To examine if the neuroprotective effect is mediated by its stimulation of production of neurotrophic factors from astrocytes, we investigated the effect of T10 on synthesis and release of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) in rat astrocyte cultures. T10 did not affect the synthesis and release of either BDNF or GDNF. However, it significantly increased NGF mRNA expression. It also increased both intracellular NGF and NGF level in culture medium. These results indicate that the neuroprotective effect of T10 might be mediated, at least in part, via a stimulation of the production and release of NGF in astrocytes. Authors Bing Xue and Jian Jiao contributed equally to this work.