少突胶质细胞的钙信号

钙是细胞内重要的第二信使,参与机体内多种生理过程,其胞内的钙信号传递依赖于胞内外的钙离子(Ca2+)浓度差,表现为胞质内钙的变化.Ca2+进入细胞内与钙的受体如钙调素(calmodulin,CaM)结合后发挥系列效应.以往认为Ca2+仅在兴奋性细胞中起传递信号作用,但近年来随着研究的深入,发现无论是兴奋性还是非兴奋性细胞,钙都作为第二信使参与信号转导及基因的表达调控.少突胶质细胞是中枢神经系统髓鞘形成细胞,被认为是中枢神经系统中一种非兴奋性细胞,其对于细胞外的刺激可表现为胞内钙浓度的变化从而调控细胞活动.     

癫痫大鼠海马神经元和星形胶质细胞的病理演变

目的　探讨癫痫大鼠海马神经元和星形胶质细胞在点燃后各期的病理特点、时序及机制。方法　针对匹罗卡品癫痫大鼠模型,行Nissl、免疫组化和HE染色,观察海马神经元及星形胶质细胞的病理变化。结果　癫痫持续状态后超急性期（4h）,CA3区神经元呈嗜酸性变性、胞浆深染;急性期（24h）,嗜酸性变性最为显著,神经元固缩、核仁消失、突起断裂,星形胶质细胞水肿;缄默期（7d）,CA3、CA1区及门区神经元大量坏死、脱失,胶质增生肥大,海马构筑紊乱;慢性期（6w）,CA3、CA1区出现胶质瘢痕,遗有形态正常的神经元,且颗粒细胞层增厚。结论　癫痫时海马神经元先于星形胶质细胞发生病理改变,二者均参与癫痫发生。     

小胶质细胞与癫痫的关系研究进展

正癫痫是一种常见的神经系统疾病。目前,全球约有癫痫病人5 000万,我国约有900万,而且每年有40～50万的新发病人~([1])。反复的癫痫发作导致病人发育迟缓、认知障碍,以及精神行为异常等。癫痫病人不仅生活质量低下,而且死亡年龄比一般人群     

红藻氨酸诱发大鼠复杂部分性癫痫发作的海马神经元和星形胶质细胞反应及相互关系

目的：观察大鼠癫痫发作后海鸟内神经元与星形胶质细胞反应变化的时空效应及相互关系。方法：以红藻氨酸诱发的大鼠复杂部分性癫痂发作为模型，利用免疫组织化学法，在原位显示癫痫发作后15、30、60、90、120、180min6个时间点海马神经元Fos蛋白及星形胶质细胞内胶质原纤维酸性蛋白（GFAP）的表达变化、相互关系及分布规律。结果：致痫后15min海马内GFAP表达开始增多，60min达高峰。Fos阳性神经元在癞痴诱发后30min开始出现，120min达高峰。海马内GFAP阳性细胞与Fos阳性神经元分布规律基本一致。结论：在癫痫病理状态下，海马内星形胶质细胞的反应略早于神经元，两者之间分布呈平行关系，它们之间可能存在着复杂的信息通讯，以复合体的形式其同对各种病理生理刺激作出反应。     

青霉素对体外培养鼠脑γ—氨基丁酸能神经元及胶质细胞的影响

经免疫细胞化学方法观察了分离培养４天，、１０天鼠大脑皮层、海马ＧＡＢＡ能神经元以及ＧＦＡＰ免疫反应阳性星形胶质细胞对大剂量致痫剂青霉素的反应。结果大剂量ＰＥＮ可引起培养海马及皮层γ－氨基丁酸能神经元数目明显减少，星形胶质细胞显著增生，且尤以海马胶质细胞增生明显。提示：（１）脑内尤其海马区星形胶南细胞增生与癫痫发生，发展有一定的关系。（２）传统致痫剂ＰＥＮ可能是通过抑制ＧＡＢＡ能神经元功能、刺激星形     

伴癫痫发作的髓鞘少突胶质细胞糖蛋白抗体相关疾病的临床特点

目的 描述伴癫痫发作的髓鞘少突胶质细胞糖蛋白抗体相关疾病的临床特点。方法 回顾性分析自2016年4月至2021年4月就诊于郑州大学第五附属医院和郑州大学第一附属医院血或脑脊液MOG抗体检测阳性患者,了解病程中出现癫痫发作患者的一般资料、临床特点、实验室检查、影像学检查、脑电图结果、治疗及预后情况。结果 MOG抗体阳性患者中15例(21.4%,15/70)首次发病时出现癫痫发作,其中儿童11例,成人4例,平均发病年龄17.4岁(3～53岁)。临床表现为ADEM样6例,单侧皮质脑炎5例,孤立性癫痫发作3例,抗NMDAR脑炎1例。癫痫发作类型为全面强直阵挛发作10例,局灶性运动性发作3例,癫痫持续状态2例,临床上除了伴随头痛、发热以及对应皮质相关症状外,亦可累及脑干、视神经及脊髓。急性期脑电图多见异常,受累侧对应皮质区域呈慢波改变。头部MRI多见皮质受累,表现为局部皮质肿胀,脑沟变浅,FLAIR呈高信号,增强可见脑膜线样强化。急性期给予糖皮质激素或联合人免疫球蛋白治疗效果好,经过2～31 m随访,6例患者出现复发,5例患者加用免疫抑制剂治疗,10例患者延长抗癫痫药物治疗。结论 癫痫发作在MO...     

难与脑胶质瘤病鉴别的脑胶质细胞增生症一例

脑胶质细胞增生症是一种颅内良性病变，而脑胶质瘤病是一种罕见的中枢神经系统肿瘤性病变，二者在临床表现上极为相似，难以鉴别，只有经过病理诊断才可以确诊。我们诊断脑胶质细胞增生症1例，报道如下。     

青霉素对体外培养鼠脑γ－氨基丁酸能神经元及胶质细胞的影响

以免疫细胞化学方法观察了分离培养４天、１０天鼠大脑皮层、海马ＧＡＢＡ能神经元以及ＧＦＡＰ免疫反应阳性星形胶质细胞对大剂量致痫剂青霉素（Ｐｅｎｉｃｉｌｉｎ，ＰＥＮ）的反应。结果大剂量ＰＥＮ（３００μ／ｍｌ培养液）可引起培养海马及皮层γ－氨基丁酸（γ－ａｍｉｎｏｂｕｔｙｒｉｃａｃｉｄ，ＧＡＢＡ）能神经元数目明显减少，星形胶质细胞显著增生，且尤以海马胶质细胞增生明显。提示：（１）脑内尤其海马区星形胶质细胞增生与癫痫发生、发展有一定的关系；（２）传统致痫剂ＰＥＮ可能是通过抑制ＧＡＢＡ能神经元功能、刺激星形胶质细胞增生，从而导致癫痫发作     

一种从新鲜脑胶质瘤标本中分离小胶质细胞的改良方法

目的 建立一种快速有效从脑胶质瘤组织中分离小胶质细胞的改良方法.方法 采用密度梯度离心法联合磁珠分选法从脑胶质瘤组织中分离小胶质细胞.用流式细胞术、Western blot 和细胞免疫荧光检测细胞纯度,流式检测免疫表型,趋化及吞噬实验检测其生物学功能;对从不同级别胶质瘤组织分离的小胶质细胞产量进行定量分析.结果 收获细胞具有小胶质细胞典型形态及Iba1染色阳性,纯度可达(95.1±4.2)％;流式细胞术检测显示其表达CD11b、HLA-DR等,并对ATP 的趋化作用呈浓度依赖性,且在体外具有良好的吞噬乳胶微球(latex beads)的功能.此外,每克胶质瘤组织分离小胶质细胞细胞产量:低级别组(n=4),(4.0±0.5) ×105;高级别组(n=8),(4.3±0.4) ×105,两组差异无统计学意义(P＞0.05).结论 利用改良的分离小胶质细胞方法能从新鲜脑胶质瘤组织中快速获得大量高纯度小胶质细胞.     

一种改进的星形胶质细胞原代培养方法

目的改进大鼠大脑皮质星形胶质细胞的体外培养,旨在通过较简便的方法获得高纯度形态典型的星形胶质细胞,为研究星形胶质细胞的生物学作用提供实验模型。方法以新生大鼠为星形胶质细胞来源,利用不同规格的吸头相互叠套,逐步机械吹打,使细胞分散,制备单细胞悬液;获得的单细胞悬液用差速黏附处理去除成纤维细胞,原代培养14d后,恒温振荡法去除小胶质细胞等杂质细胞;胶质细胞原纤维酸性蛋白(GFAP)和S100β免疫荧光共染色,鉴定细胞纯度。结果这种改进的星形胶质细胞培养方法 ,分离培养出星形胶质细胞,阳性率达95%以上。结论采用机械吹打方法建立原代星形胶质细胞培养体系,是一种比较简便、值得推广的可用于体外细胞培养研究工作的有效方法。     

Localization of prostaglandin endoperoxide synthase in neurons and glia in monkey brain

The localization of prostaglandin endoperoxide synthase in monkey brain was investigated by the immunoperoxidase method using the monoclonal antibody (PES-7) raised against the enzyme purified from bovine seminal vesicle. The frozen sections with 30-microns thickness were employed after the brain was fixed with perfusion of 2% paraformaldehyde in phosphate-buffered saline. The immunoreactivity was most intense in the neurons of cerebral cortex and hippocampus, and was moderate in the neurons of caudate nucleus, putamen, globus pallidus and amygdala, while it was relatively weak in glial cells in the whole brain regions including the white matter. The majority of neurons showed the immunoreactivity in the somata and proximal dendrites, but exceptionally in the pyramidal cells of the hippocampus, positive staining was also observed in the apical dendrites. In the cerebellum, the immunoreactivity in both neurons and glia was rather faint as compared with that in other regions. Positive staining was not significantly observed in the vasculatures and arachnoid membranes. These findings indicate that most of neuronal and glial cells in monkey brain contain the enzyme of the rate-limiting and initial step of the biosynthesis of prostaglandins which regulate a variety of neural functions.     

Effects of urethane anaesthesia on sensory processing in the rat barrel cortex revealed by combined optical imaging and electrophysiology

The spatiotemporal dynamics of neuronal assemblies evoked by sensory stimuli have not yet been fully characterised, especially the extent to which they are modulated by prevailing brain states. In order to examine this issue, we induced different levels of anaesthesia, distinguished by specific electroencephalographic indices, and compared somatosensory‐evoked potentials (SEPs) with voltage‐sensitive dye imaging (VSDI) responses in the rat barrel cortex evoked by whisker deflection. At deeper levels of anaesthesia, all responses were reduced in amplitude but, surprisingly, only VSDI responses exhibited prolonged activation resulting in a delayed return to baseline. Further analysis of the optical signal demonstrated that the reduction in response amplitude was constant across the area of activation, resulting in a global down‐scaling of the population response. The manner in which the optical signal relates to the various neuronal generators that produce the SEP signal is also discussed. These data provide information regarding the impact of anaesthetic agents on the brain, and show the value of combining spatial analyses from neuroimaging approaches with more traditional electrophysiological techniques.     

Glial response to neuronal activity: GFAP-mRNA and protein levels are transiently increased in the hippocampus after seizures

We have recently demonstrated that electrically induced seizures lead to dramatic increases in mRNA for GFAP in areas in which seizures occur. The present study evaluates the time course of the changes in the GFAP-mRNA levels after seizures and the relationship between these changes and GFAP protein levels to understand the role of neuronal activity in regulating glial gene expression. GFA protein and mRNA levels were measured in hippocampi from rats in which seizures were induced by: (1) 50-Hz stimulus trains delivered 12 times over the course of 1 day via indwelling electrodes implanted chronically in the CA3 region of the hippocampus; and (2) intraperitoneal injections of pentylenetetrazol. In the case of the electrically induced seizures, we also compared the glial response in animals that had never experienced a seizure with the response in animals that previously had been kindled but had not experienced a seizure for 30 days. Electrically induced seizures led to rapid transient increases in GFAP-mRNA levels in the hippocampus ipsi- and contralateral to the stimulation. GFAP-mRNA increased about five-fold 1 day after the end of seizure activity and returned to near-control levels by 4 days. There were no detectable increases in GFA protein at 1 day but by 2 days GFA protein levels had increased about two-fold. GFA protein levels remained elevated until 4 days poststimulation and then began to decrease. The responses were similar when seizures were induced in kindled animals, except that the GFAP protein levels remained elevated for somewhat longer. Pentylenetetrazol-induced seizures also led to increases in GFAP-mRNA and GFA protein levels but the extent of the increases was not as great as after kindled seizures. These results suggest that gene expression in astrocytes in likely to be upregulated in any situation in which seizures occur. These changes may fundamentally alter the homeostatic activities of the affected astrocytes which, in turn, could have important consequences on the development of the epileptic state.     

Combined retrograde labeling and calcium imaging in spinal cord and brainstem neurons of the lamprey

Neurons in the brainstem and spinal cord of the lamprey were retrogradely labeled with Calcium Green-dextran, an indicator dye that increases its fluorescence when intracellular calcium levels increase. Optical signals could be recorded from these labeled neurons during spinal cord stimulation, nerve stimulation, or spontaneous activity, up to 4 days after dye application and for distances of 5–14 mm away from the application site. Optical signals were enhanced by 4-AP, a potassium channel blocker, and blocked by cadmium, a calcium channel blocker. Taken together, the results suggest that the optical signals recorded from labeled neurons were due to calcium influx during electrical activity. Thus, retrograde labeling with calcium indicator dyes may provide a general purpose method for simultaneously monitoring the activity-related changes of intracellular calcium in anatomically identified groups of neurons in the lamprey nervous system.     

Spatiotemporal analyses of interactions between entorhinal and CA1 projections to the subiculum in rat brain slices

The subiculum and the entorhinal cortex (EC) are important structures in processing and transmitting information between the neocortex and the hippocampus. The subiculum potentially receives information from the EC through two routes. In addition to a direct projection from EC to the subiculum, there is an indirect polysynaptic connection. The latter uses a number of possible pathways, which all converge onto the final projection from the hippocampal field CA1 to the subiculum. In this series of experiments we investigated to what extent activity in both pathways influences population activity of subicular neurons. We used voltage sensitive dyes in combined hippocampal-EC slices of the rat to measure the spatio-temporal activity patterns. To activate the two inputs to the subiculum, stimulation electrodes were placed in the stratum oriens/alveus of CA1 and in layer III of the medial EC. The response patterns evoked in the subiculum after electrical stimulation of each of these input pathways separately were compared with the response patterns after simultaneous stimulation of both areas (medial EC + CA1). A comparison of the computed added responses of the two individual stimulations with the measured responses after simultaneous stimulation suggests that both inputs are linearly added in the subiculum with very little nonlinear interactions. This strongly suggests that in the subiculum interaction at a single cell level of the direct and the indirect pathways from the EC is an unlikely scenario.     

In vivo optical imaging of tone-evoked activity in the dorsal cochlear nucleus with a voltage sensitive dye

We investigated the use of optical imaging for observing the spatial patterns of neural activation in the dorsal cochlear nucleus (DCN) of hamsters during tonal stimulation. The patterns of activation were studied in the DCN, in vivo, following application of a voltage sensitive dye, Di-2-ANEPEQ, to the DCN surface. Beginning 60-90 min following dye application, tones were presented to the ipsilateral ear. Electrophysiological recordings after dye application revealed no significant toxicity of Di-2-ANEPEQ that affected the frequency-tuning properties of DCN neurons. We examined areas of activation in response to each of a series of test stimuli consisting of pure tones ranging in frequency from 2 to 20 kHz. For each stimulus condition, images were collected over a stimulus interval of 400 msec and averaged over 32 stimulus repetitions. These images revealed areas of activation with definable epicenters. The epicenters shifted from lateral to more medial locations on the DCN surface with increases in stimulus frequency. Comparison with electrophysiological data indicated a close parallel between the tonotopic gradient defined by optical imaging and that defined by the distribution of characteristic frequencies. The principal temporal and spatial features of these optical responses are described.     

磁敏感加权成像在轻型颅脑损伤患者中的诊断价值

目的探讨磁共振磁敏感加权成像(SWI)对轻型颅脑损伤(MTBI)患者的诊断价值。方法回顾分析32例MTBI患者(格拉斯哥昏迷量表评分13~15分)的临床资料。患者伤后1周内给予头部CT、MRI及SWI检查,结合CT及相位图排除气体、血管和颅底伪影后,SWI图上的低信号为脑内挫伤出血灶。分别记录MRI常规序列和SWI探查到的病灶数目、发生部位,并结合临床症状进行分析。结果 SWI对脑外伤微小挫伤出血灶检查阳性率明显高于CT及MRI普通序列扫描,特别是在伤后出现晕厥昏迷史或持续性出现临床症状的患者中更为明显。结论 SWI比常规CT及MRI对MTBI患者脑内微小挫伤及出血灶的检出有更高的准确性和客观的诊断价值,并对指导临床治疗及判断预后有重大意义。     

轻度创伤性脑损伤后脑组织微环境变化:多模态磁共振成像研究

目的探讨弥散张量成像(DTI)联合磁共振波谱(MRS)及磁敏感加权成像(SWI)的功能磁共振成像方法,在评估轻度创伤性脑损伤(mTBI)脑组织代谢及微结构变化的应用价值,为临床制定相应的治疗方案提供影像学参考。方法纳入21例mTBI患者和16例健康志愿者,mTBI患者在伤后4～72 h内接受T1WI、T2WI、FLAIR、DTI、MRS及SWI序列扫描,通过各序列图像及参数值评估mTBI患者伤侧脑组织和对照组内囊前肢、内囊后肢、胼胝体膝部、胼胝体压部、扣带回、半卵圆中心、额叶白质及视辐射的差异。结果两组FA值比较,仅胼胝体压部差异有统计学意义(P0.01)。mTBI组胼胝体膝部NAA/Cr值低于对照组,差异有统计学意义(P0.01)。mTBI组内囊后肢和胼胝体膝部Cho/Cr值均高于对照组,差异均有统计学意义(P0.05或0.01)。结论 FA值及NAA、Cho、Cr值能测定mTBI后脑组织水分子扩散及代谢情况,DTI联合MRS及SWI可以作为一项客观指标,定量评估mTBI患者的病情及预后。     

Simultaneous optical recording of evoked and spontaneous transients of membrane potential and intracellular calcium concentration with high spatio-temporal resolution

We have developed a system for simultaneous optical recording of transients of membrane potential and intracellular calcium concentration from mammalian brain slice preparations with high spatio-temporal resolution. Simultaneous recording was achieved by using two dedicated photodetectors together with two fluorescent indicators. Specifically, the calcium-sensitive dye Calcium Orange and the voltage-sensitive dye RH-414 were selected because they have overlapping excitation spectra, but separable emission spectra. Transverse guinea pig hippocampal slices were double-loaded by bath application of the membrane-permeant form of Calcium Orange and RH-414. Transients of intracellular calcium concentration and membrane potential associated with evoked neural activity in hippocampal areas CA1 and CA3 were recorded. Furthermore, we have recorded calcium and voltage transients associated with spontaneous epileptiform activity induced by bath application of an epileptogenic drug, 4-aminopyridine. The use of photodiode matrices (10 × 10 elements each) as detectors gives the high spatial (200 × 200 μm/element with a 10 × objective) and temporal resolution (570 μs/frame). The recording system also includes a CCD camera for obtaining images of the preparation and overlaying the image with the optically detected signals. A software package has been developed for setting up the experimental protocol(s) and for collecting, processing, displaying, and analyzing the data in an user-friendly, windows-based environment.     

Effect of tacrine on intracellular calcium in cholinergic SN56 neuronal cells

We have found earlier that the depolarization-induced release of acetylcholine from the brain could be inhibited by tacrine (tetrahydroaminoacridine) but the mechanism of this action of tacrine was not clarified (S. Tu?ek, V. Dole?al, J. Neurochem. 56 (1991) 1216). We have now investigated whether tacrine has an effect on the changes in the intracellular concentration of calcium ions ([Ca²⁺]_i) induced by depolarization. Experiments were performed on the cholinergic SN56 neuronal cell line with Fura-2 fluorescence technique of calcium imaging. The depolarization by 71 mmol/l K⁺ evoked minimum increases of [Ca²⁺]_i up to day 5 in culture. Then the response gradually increased and reached a plateau after 7 days in culture. A similar time course was observed for acetylcholinesterase activity. The effect of K⁺ ions was concentration-dependent and the concentration of 71 mmol/l K⁺ evoked maximum [Ca²⁺]_i responses. The increases of [Ca²⁺]_i did not occur in the absence of extracellular calcium. They were mediated by high voltage-activated calcium channels of the L-type and the N-type. Nifedipine (2 μmol/l; L-type calcium channel blocker) and ω-conotoxin GVIA (100 nmol/l; N-type calcium channel blocker) diminished the response to 71 mmol/l K⁺ by 53% and 39%, respectively, and their effects were additive (decrease to 8% of controls). Non-selective inorganic blocker of voltage-activated calcium channels LaCl₃ (0.1 mmol/l) decreased the response by 83%. Tacrine attenuated the [Ca²⁺]_i response in a concentration-dependent manner. At a concentration of 10 μmol/l it inhibited the [Ca²⁺]_i response by 55% and its inhibitory effect was additive with that of ω-conotoxin GVIA but not with that of nifedipine. An equimolar concentration of paraoxon, an irreversible inhibitor of cholinesterases, had no influence on [Ca²⁺]_i response. Tacrine exhibited the same inhibitory effect when paraoxon was present. In conclusion, our data indicate that high-voltage-activated calcium channels of the L-type and the N-type are both present in the SN56 cells but that they are fully expressed only after 6–7 days in culture. Tacrine attenuates the influx of calcium by inhibiting the L-type calcium channels. This inhibitory effect is not a consequence of the anticholinesterase activity of tacrine. The finding that low micromolar concentrations of tacrine may interfere with calcium-dependent events is likely to be of importance for the evaluation of the therapeutic potential of the drug.