不同生长底物对体外培养脊髓运动神经元的影响

神经元作为一种高度分化的细胞,在体外难以存活和生长,因此在体外培养时,需在容器表面包被一层类似细胞外基质的生长底物。神经元能否尽快粘贴到包被的底物上是影响神经元体外存活率的关键因素之一。细胞外基质(ECM)可为包埋在其中的细胞提供适宜的物理和化学微环境,同时形成一个网状支架供     

胚胎大鼠脊髓运动神经元的体外培养及鉴定

本实验建立了体外胚胎大鼠脊髓运动神经元的分离培养,并进行鉴定。取孕15d SD大鼠胚胎的脊髓腹侧组织,用胰蛋白酶和胶原酶消化分离成单细胞悬液,进行原代细胞培养,应用神经元特异性的烯醇化酶(NSE)抗体和抗神经微丝抗体-SMI32单克隆抗体对培养细胞进行鉴定,同时行尼氏染色。结果分离培养的细胞鉴定为脊髓运动神经元(SMN),SMN在体外适宜的条件下可存活4周左右,可作为神经科学研究的一种手段。     

运动神经元营养因子对大鼠脊髓撞击伤修复的影响

成年Wistar大鼠32只，分为4组．分别按Alien法制成脊髓完全性（545gcf）和不完全性（21gcf）损伤模型．每种损伤模型文分别制成MNTF的实验组和盐水对照组。术后4周，分别做Glees、Nissl染色和ChAT、GFAP抗体的免疫组织化学反应，在镜下观察了运动神经元营养因子对脊髓急性撞击伤病理变化和再生的影响。结果表明：运动神经元营养因子对Allen法所致的完全性脊髓损伤修复的作用不明显，但对不完全性脊髓损伤具有局限脊髓空洞、促进瘢痕愈合和神经再生的作用。     

大鼠选择性运动神经元死亡的脊髓器官型培养模型的建立

利用谷氨酸转运体抑制剂苏-羟天冬氨酸(threo-hydroxyaspartate，THA)制备大鼠选择性运动神经元死亡的脊髓器官型培养模型。取出生后8天乳鼠的腰段脊髓组织切片做脊髓器官型培养，在培养液中分别加入不同浓度THA(50μmol／L、100μmol／L、500μmol／L)，用神经元的特异性免疫组化染色SMI-32对脊髓腹角α运动神经元及背角中间神经元计数，测定培养液中乳酸脱氢酶(LDH)的含量，并与对照组做比较。结果显示对照组α运动神经元数目恒定，THA可以引起剂量依赖性的α运动神经元数目减少和培养液中LDH含量增高，其中加用THA 100μmol／L后3周后即有α运动神经元数目较对照组明显减少，而脊髓背角的中间神经元数目无显著差异。利用谷氨酸转运体抑制剂THA 100μmol／L可以制成选择性运动神经元损伤模型，为进一步研究肌萎缩侧索硬化(ALS)的发病机制及探讨神经保护治疗提供了有效的方法。     

食管上皮细胞的体外原代培养及形态学观察

食管上皮细胞为未角化的复层鳞状上皮,我们借鉴了表皮细胞的培养方法,摸索了新生牛食管上皮细胞体外原代培养的条件,并进行了形态学观察和细     

新生大鼠脊髓少突胶质细胞体外培养与鉴定

本研究探索利用新生大鼠脊髓培养和纯化少突胶质细胞的方法。取新生大鼠全脊髓,胰酶消化并吹打分散细胞,用含20％胎牛血清的DMEM培养液原代混合细胞培养,细胞铺满瓶底后传代培养。用抗半乳糖脑苷脂抗体和抗胶质原纤维酸性蛋白抗体进行细胞分类免疫组化鉴定。结果显示:少突胶质细胞纯度可达98％以上,表明新生大鼠脊髓是少突胶质细胞体外培养的理想取材部位。本操作简单易行,可以在短时间内获得足量的纯化的少突胶质细胞。     

新生大鼠心肌细胞的体外培养

心肌细胞培养作为一种体外实验研究模型,可以更方便地从细胞和分子水平研究心血管疾病的发病机制,成为心血管疾病研究的一项主要手段和基本技术。如何使心肌细胞培养的方法更为简单并且使分离的心肌细胞达到理想的存活率和纯度,是体外培养心肌细胞模型的关键问题。我们在本实验室多年新生大鼠心肌细胞培养的经验和方法的基础上加以改进,获得了简单并且稳定、可靠的心肌细胞培养的方法。     

高压氧前处理脊髓损伤大鼠前角运动神经元的凋亡*☆

背景：脊髓损伤后难以修复,损伤后保护残存的神经元是促进神经再生的关键。 目的：验证高压氧预处理可以通过抑制早期的细胞凋亡来保护脊髓前角运动神经元。 方法：随机将26只雄性Wistar大鼠等分成模型组和实验组。实验组在给予高压氧5 d后与模型组同时制作脊髓T9~10全横断模型。 结果与结论：尼氏染色显示脊髓T9~T10全横断后8 h及1 d,脊髓前角的浓染的细胞多见,与模型组相比,实验组脊髓前角浓染的细胞较少。TUNEL染色也显示脊髓T9~T10全横断后脊髓损伤后8 h~1 d,2组大鼠脊髓前角内均可见大量的凋亡神经元,3 d时凋亡神经元数量减少。相比于模型组,高压氧预处理8 h,1 d后大鼠脊髓前角凋亡神经元较少(P < 0.05,        P < 0.01)。说明高压氧预处理能对脊髓损伤后前角运动神经元起保护作用。       

新生大鼠脊髓运动神经元的纯化培养与鉴定

背景：神经元是有丝分裂后的细胞,体外培养很难存活。脊髓运动神经元的分离、纯化和培养同时也是细胞培养的技术难点。 目的：建立新生大鼠脊髓运动神经元培养体系,并予以分类鉴定和测定其纯度。 方法：取新生大鼠脊髓腹侧组织分离成细胞悬液,经密度梯度离心及差速贴壁后纯化培养,采用免疫细胞化学双标染色法对培养盖片上的细胞予以鉴定、分类,结合Hoechst荧光染核,计数各细胞成分的含量。 结果与结论：细胞贴壁生长良好,神经元占85.8%,其中运动神经元达71.6%,星形胶质细胞占7.8%,NF200和胶质纤维酸性蛋白染色皆为阴性的细胞占6.4%。结果说明,取新生大鼠腹侧脊髓组织结合密度梯度离心及差速贴壁接种法可以培养出高纯度的脊髓运动神经元。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

维甲酸、音猬因子对大鼠脊髓神经干细胞向运动神经元样细胞分化的影响

目的:分离大鼠胚胎的脊髓神经干细胞进行体外培养,探讨维甲酸(RA)、音猬因子(Shh)诱导其向运动神经元样细胞分化. 方法:应用无血清培养技术分离培养脊髓神经干细胞,通过5-溴-2-脱氧尿苷标记、免疫荧光显色检测细胞增殖、分化情况;培养液分组添加Shh、 RA或Shh+RA,观察神经干细胞向运动神经元样细胞的分化情况. 结果:大鼠胚胎脊髓可成功分离神经干细胞,分化后可表达神经元、星形胶质细胞的特异性抗原;诱导分化后结果显示Shh组未检测到胆碱乙酰转移酶阳性细胞,RA组为20.63%, Shh+RA组为66.84%,其差异具统计学意义.结论:从大鼠胚胎脊髓可成功分离神经干细胞,Shh、 RA可不同程度地诱导脊髓神经干细胞分化为运动神经元样细胞.     

Hyperexcitability of cultured spinal motoneurons from presymptomatic ALS mice

ALS (amyotrophic lateral sclerosis) is an adult-onset and deadly neurodegenerative disease characterized by a progressive and selective loss of motoneurons. Transgenic mice overexpressing a mutated human gene (G93A) coding for the enzyme SOD1 (Cu/Zn superoxide dismutase) develop a motoneuron disease resembling ALS in humans. In this generally accepted ALS model, we tested the electrophysiological properties of individual embryonic and neonatal spinal motoneurons in culture by measuring a wide range of electrical properties influencing motoneuron excitability during current clamp. There were no differences in the motoneuron resting potential, input conductance, action potential shape, or afterhyperpolarization between G93A and control motoneurons. The relationship between the motoneuron's firing frequency and injected current (f-I relation) was altered. The slope of the f-I relation and the maximal firing rate of the G93A motoneurons were much greater than in the control motoneurons. Differences in spontaneous synaptic input were excluded as a cause of increased excitability. This finding identifies a markedly elevated intrinsic electrical excitability in cultured embryonic and neonatal mutant G93A spinal motoneurons. We conclude that the observed intrinsic motoneuron hyperexcitability is induced by the SOD1 toxic gain-of-function through an aberration in the process of action potential generation. This hyperexcitability may play a crucial role in the pathogenesis of ALS as the motoneurons were cultured from presymptomatic mice.     

Calreticulin expression in spinal motoneurons of the rat

We have examined the expression of calreticulin in rat spinal motoneurons in order to reveal the occurrence and distribution of Ca²⁺-storage organelles in these neurons. Calreticulin, the non-muscle equivalent of calsequestrin, is the low-affinity, high-capacity calcium-binding protein responsible for intracompartmental Ca²⁺-storage in a number of different cell types. The results of the present immunohistochemical study show that all spinal motoneurons express calreticulin at approximately the same level; no significant differences in cytoplasmic immunostaining intensity were observed between different motoneuron pools or between small and large spinal motoneurons. Immunoelectron microscopy revealed that the intracellular localization of calreticulin within spinal motoneurons was confined to the endoplasmic reticulum and to spherical or pleiomorphic, frequently ‘coated’ vesicles with a diameter ranging between 120 and 150 nm. Some of these vesicles may represent the so-called calciosomes, the intracellular Ca²⁺-storage vesicles described in liver cells and in cerebellar Purkinje cells. The molecular components responsible for the uptake and release of Ca²⁺ from the Ca²⁺-storage organelles in spinal motoneurons still remain to be identified.     

Sexual activity and the morphology of steroid-sensitive rat spinal motoneurons

In adult male rats, differential sexual experience has been shown to alter plasma androgen titers. Alterations in androgen levels have also been shown to significantly alter the structure of neurons in the spinal nucleus of the bulbocavernosus (SNB), a spinal motor nucleus that innervates perineal muscles involved in copulatory behavior. To determine if experientially induced alterations in androgen levels might alter SNB structure, male rats were assigned to one of three groups: sexually active, sexually inactive but exposed to inaccessible cycling females, and isolated. After 4 weeks of differential sexual experience, the soma size, total arbor, density, maximal fiber length, and frequency distribution of lengths of dendrites were examined in SNB motoneurons. No differences in motoneuron morphology were observed, suggesting that these motoneurons are not sensitive to socially induced alterations in androgen titers.     

Summation of effective synaptic currents and firing rate modulation in cat spinal motoneurons

The aim of this study was to examine how cat spinal motoneurons integrate the synaptic currents generated by the concurrent activation of large groups of presynaptic neurons. We obtained intracellular recordings from cat triceps surae motoneurons and measured the effects of repetitive activity in different sets of presynaptic neurons produced by electrical stimulation of descending fibers or peripheral nerves and by longitudinal vibration of the triceps surae muscles (to activate primary muscle spindle Ia afferent fibers). We combined synaptic activation with subthreshold injected currents to obtain estimates of effective synaptic currents at the resting potential (I(Nrest)) and at the threshold for repetitive discharge (I(Nthresh)). We then superimposed synaptic activation on suprathreshold injected current steps to measure the synaptically evoked change in firing rate. We studied eight different pairs of synaptic inputs. When any two synaptic inputs were activated concurrently, both the effective synaptic currents (I(Nrest)) and the synaptically evoked changes in firing rate generally were equal to or slightly less than the linear sum of the effects produced by activating each input alone. However, there were several instances in which the summation was substantially less than linear. In some motoneurons, we induced a partial blockade of potassium channels by adding tetraethylammonium (TEA) or cesium to the electrolyte solution in the intracellular pipette. In these cells, persistent inward currents were evoked by depolarization that led to instances of substantially greater-than linear summation of injected and synaptic currents. Overall our results indicate that the spatial distribution of synaptic boutons on motoneurons acts to minimize electrical interactions between synaptic sites permitting near linear summation of synaptic currents. However, modulation of voltage-gated conductances on the soma and dendrites of the motoneuron can lead to marked nonlinearities in synaptic integration.     

Na(+) entry through AMPA receptors results in voltage-gated k(+) channel blockade in cultured rat spinal cord motoneurons

alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor currents, evoked with the agonist kainate, were studied with the gramicidin perforated-patch-clamp technique in cultured rat spinal cord motoneurons. Kainate-induced currents could be blocked by the AMPA receptor antagonist LY 300164 and displayed an apparent strong inward rectification. This inward rectification was not a genuine property of AMPA receptor currents but was a result of a concomitant decrease in outward current at potentials positive to -40.5 +/- 1.3 mV. The AMPA receptor current itself was nearly linear (rectification index 0.91). The kainate-inhibited outward current had a reversal potential close to the estimated K(+) equilibrium potential and was blocked by 30 mM tetraethylammonium. When voltage steps were applied, it was found that kainate inhibited both the delayed rectifier K(+) current K(V) and the transient outward K(+) current, K(A). The kainate-induced inhibition of K(+) currents was dependent on ion flux through the AMPA receptor, because no change in the membrane conductance was noticed in the presence of LY 300164. Removing extracellular Ca(2+) had no effect, whereas replacing extracellular Na(+) or clamping the membrane close to the estimated Na(+) equilibrium potential during kainate application attenuated the inhibition of the K(+) current. Sustained Na(+) influx induced by application of the Na(+) ionophore monensin could mimic the effect of kainate on K(+) conductance. These findings demonstrate that Na(+) influx through AMPA receptors results in blockade of voltage-gated K(+) channels.     

The morphological changes of the spinal motoneurons after peripheral nerve transection in the chicken

The cellular response of motoneurons and glial cells of the chicken spinal cord was observed following brachial plexectomy. The axotomized motoneurons initially showed an irregular nuclear membrane. Subsequently, they showed the appearance of a perineuronal space and the increase in number of glycogen granules. At 10 and 20 d post-operatively, the axon reaction reached a peak and the axotomized motoneurons contained abundant glycogen granules, and tended to an increase electron density in electron microscopy or an increased basophilia in light microscopy compared to those of the control. Elongated microglial cells appeared as satellites to the axotomized cells. The perineuronal space extended with the post-operative days. From 30 post-operative days forward, the axotomized motoneurons recovered with the post-operative days. The axotomized motoneurons did not show chromatolysis during axon reaction.     

AMPA-evoked acetylcholine release from cultured spinal cord motoneurons and its inhibition by GABA and glycine

The release of [(3)H]acetylcholine evoked by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and its inhibition mediated by GABA(A) and glycine receptors were studied in superfused cultured rat embryo spinal cord motoneurons prelabeled with [(3)H]choline. AMPA elicited tritium release, possibly representing [(3)H]acetylcholine release in a concentration-dependent manner. The release was external Ca(2+)-dependent and was sensitive to Cd(2+) ions, omega-conotoxin GVIA and omega-conotoxin MVIIC, but not to nifedipine, suggesting the involvement of N-, P/Q-, but not L-type Ca(2+) channels. The AMPA effect was insensitive to tetrodotoxin. The glutamate receptors involved are AMPA type since the AMPA-evoked [(3)H]acetylcholine release was blocked by LY303070 and was potentiated by the antidesensitizing agent cyclothiazide. Muscimol inhibited completely the AMPA effect on [(3)H]acetylcholine release; muscimol was potentiated by diazepam and antagonized by SR95531, indicating the involvement of benzodiazepine-sensitive GABA(A) receptors. Glycine, acting at strychnine-sensitive receptors, also inhibited the effect of AMPA, but only in part. The inhibitory effects of muscimol and glycine are additive.We conclude that glutamate can act at AMPA receptors sited on spinal motoneurons to evoke release of acetylcholine. GABA and glycine, possibly released as cotransmitters from spinal interneurons, inhibit glutamate-evoked acetylcholine release by activating GABA(A) and glycine receptors on motoneurons.     

Delayed riluzole treatment is able to rescue injured rat spinal motoneurons

The effect of delayed 2-amino-6-trifluoromethoxy-benzothiazole (riluzole) treatment on injured motoneurons was studied. The L4 ventral root of adult rats was avulsed and reimplanted into the spinal cord. Immediately after the operation or with a delay of 5, 10, 14 or 16 days animals were treated with riluzole (n=5 in each group) while another four animals remained untreated. Three months after the operation the fluorescent dye Fast Blue was applied to the proximal end of the cut ventral ramus of the L4 spinal nerve to retrogradely label reinnervating neurons. Three days later the spinal cords were processed for counting the retrogradely labeled cells and choline acetyltransferase immunohistochemistry was performed to reveal the cholinergic cells in the spinal cords. In untreated animals there were 20.4+/-1.6 (+/-S.E.M.) retrogradely labeled neurons while in animals treated with riluzole immediately or 5 and 10 days after ventral root avulsion the number of labeled motoneurons ranged between 763+/-36 and 815+/-50 (S.E.M.). Riluzole treatment starting at 14 and 16 days after injury resulted in significantly lower number of reinnervating motoneurons (67+/-4 and 52+/-3 S.E.M., respectively). Thus, riluzole dramatically enhanced the survival and reinnervating capacity of injured motoneurons not only when treatment started immediately after injury but also in cases when riluzole treatment was delayed for up to 10 days. These results suggest that motoneurons destined to die after ventral root avulsion are programmed to survive for some time after injury and riluzole is able to rescue them during this period of time.