流式细胞仪分选thyl-GFP-J转基因小鼠皮层及海马神经元

目的获得活体哺乳动物脑内单一纯化的神经元群。方法用RTPCR和激光共聚焦显微镜扫描脑片鉴定thyl-GFP-J转基因小鼠，取2月龄鉴定阳性小鼠皮层和海马组织，应用番木瓜蛋白酶分离系统制备脑组织单细胞悬液，PI标记死亡细胞，流式细胞仪荧光激活细胞分类技术（FAcs）分选收集GFP^＋和PI-的存活神经元，并抽提获得细胞的RNA和蛋白。结果阳性转基因小鼠DNA的PCR扩增鉴定显示为内参（324bp）和所转基因（173bp）两条带，脑片的激光共聚焦扫描结果显示海马和皮层均可见大小较均一的圆点状绿色荧光。经FACS分选后的细胞几乎全都发出绿色荧光，每次产量约为0．5～1×10^6个存活神经元。获得的纯化神经元中抽提的RNA和蛋白可用于RT-PCR和westernblot检测。结论利用FACS可以从thyl-GFP-J转基因小鼠脑内获得单一纯化的存活神经元群。该技术的应用将为活体神经元细胞特异性的基因表达和蛋白定量分析研究提供一个可行方案。     

体外培养小鼠皮质神经元感染HSV-1后的细胞凋亡

目的 :探讨HSV 1对原代培养神经元细胞凋亡的影响。方法 :用TUNEL方法结合流式细胞术、DNA电泳、免疫荧光技术 ,检测原代培养第 3天和第 7天小鼠皮质神经元感染HSV 110h后凋亡细胞变化情况。结果 :病毒组DNA梯型条带被阻止。第 3天各组凋亡细胞百分数为 :N ,14 0 5 % :V1,8 18% ;V2 ,4 97% ;NS ,2 2 13 % ;V1S ,9 99% ;V2S ,5 75 %。第 7天为 :N ,9 2 % ;V1,8 71% ;NS ,18 72 % ;V1S ,9 66%。结论 :山梨醇可以诱导神经元凋亡 ,HSV 1能阻止原代培养的小鼠皮质神经元凋亡且与病毒毒力有关。     

海马神经元兴奋性毒性模型的建立及其意义

目的探讨不同浓度谷氨酸对海马神经元的损伤作用,流式细胞仪在建立理想的兴奋性毒性模型中的应用。方法在体外原代培养10d的海马神经元中分别加入不同浓度的谷氨酸(100、200、400、600、800μmol/L),24h后相差显微镜下观察细胞形态变化,用MTT法检测存活率和流式细胞仪检测凋亡率以评定谷氨酸对海马神经元的损伤程度。结果不同浓度的谷氨酸组与对照组的细胞存活率差异有显著性(P<0.01),并呈浓度依赖性,随着谷氨酸浓度的升高,神经元的存活率降低;谷氨酸终浓度(100、200、400μmol/L)组的细胞凋亡率与对照组比较差异有显著性(P<0.01);600和800μmol/L谷氨酸组的细胞凋亡率与对照组比较差异无显著性(P>0.05),但细胞凋亡率随着谷氨酸浓度的增加而降低。结论过高浓度的谷氨酸导致细胞急性坏死而非迟发性凋亡,运用流式细胞仪检测体外培养海马神经元凋亡率是一种特异性高的检测方法,值得推广。     

加兰他敏对APP/PS1转基因小鼠海马区星形胶质细活化及C/EBPβ表达的影响

目的研究加兰他敏对APP/PS1转基因小鼠海马区星形胶质细胞活化、C/EBPβ表达及行为学的影响。方法选取10月龄雄性APP/PS1转基因小鼠20只,随机分为模型对照组(10只)和治疗组(10只),同月龄、同背景的C57BL/6野生型雄性小鼠10只作为正常对照组。治疗组皮下注射加兰他敏溶液5mg/kg,2次/d,连续治疗8周,正常对照组和模型对照组给予皮下注射等量生理盐水。应用Morris水迷宫实验于干预治疗8周后开始测定各组小鼠空间学习记忆能力,连续7d,采用免疫组织化学、免疫荧光及Western-blot方法观察各组小鼠海马区星形胶质细胞活化及C/EBPβ表达水平。结果与正常对照组相比,模型对照组和治疗组小鼠Morris检测第5、6天平均逃避潜伏期延长,穿越平台次数减少(P0.05,P0.05),而治疗组其逃避潜伏期较模型对照组缩短(P0.05),穿越平台次数增多(P0.05);同时治疗组小鼠星形胶质细胞活化被明显抑制,胶质纤维酸性蛋白(GFAP)的阳性表达面积〔(5.003±0.823)%〕及C/EBPβ的表达量(87.711±14.622)较模型对照组〔(7.116±1.040)%,119.920±16.901〕明显减少(P0.05,P0.05)。结论加兰他敏改善APP/PS1转基因AD小鼠的学习记忆能力可能与其抑制星形胶质细胞的活化及C/EBPβ的表达有关。     

姜黄素对APP/PS1双转基因小鼠认知功能、炎症反应及海马区突触素表达的影响

目的 探讨姜黄素对APP/PS1双转基因小鼠认知功能、炎症反应及海马区突触素表达的影响。方法 60只6月龄APP/PS1双转基因雄性小鼠随机分为A组、B组和C组,各20只;A组采用姜黄素100mg/kg/d加入小鼠饲料喂养,B组采用姜黄素300mg/kg/d喂养,C组采用姜黄素600mg/kg/d喂养;3组均喂养6个月。治疗前、治疗3、6个月,采用Morris水迷宫实验评估小鼠认知功能,采用免疫吸附试验法检测尾静脉血血清白介素-6（IL-6）、肿瘤坏死因子-α（TNF-α）等炎症因子水平;治疗6个月,采用免疫组化染色法检测小鼠海马 CA1 区突触素表达情况。结果 姜黄素治疗3、6个月,3组小鼠认知功能明显改善（P<0.05）,血清IL-6、TNF-α水平明显降低（P<0.05）。与A组比较,B组和C组治疗3、6个月认知功能明显改善（P<0.05）,血清IL-6、TNF-α水平均明显降低（P<0.05）,海马CA1区突触素表达水平明显升高（P<0.05）。而B组与C组均无统计学差异（P>0.05）。结论 姜黄素有助于改善APP/PS1双转基因小鼠海马突触素表达,抑制小鼠炎症反应,改善小鼠认知功能。     

转基因小鼠荧光神经元结构与功能之间关联的建立——膜片钳记录结合激光共聚焦三维重建

目的在细胞水平建立神经元结构和功能之间的关联。方法利用D1多巴胺受体表达红色荧光蛋白的细菌人工染色体(bacterial artifical chromosome,BAC)转基因小鼠制备脑片,对D1多巴胺受体荧光阳性纹状体中等多棘神经元(medial spiny neurons,MSNs)进行膜片钳电生理记录和细胞标记,再经激光共聚焦系统对该神经元进行结构的三维重建,观察MSN树突分支密度以及树突棘形态学特点。结果 (1)电生理结果提示所标记的细胞具有偏超级化的静息膜电位(-87mV)、较小的输入电阻(16.4 MΩ)及较长的动作电位潜伏期(172ms)等典型的MSN电生理学特征。(2)三维重建结果可见细胞胞体略成圆锥体,树突呈放射状向四周发散。(3)进行树突棘重塑后发现MSNs平均树突棘长度(2.37±0.14)μm,平均宽度为(1.39±0.14)μm。结论描述神经元功能的膜片钳数据与三维重建的细胞形态学数据相结合的方法可建立神经元结构和功能之间的关联。     

小胶质细胞在SOD1-G93A转基因小鼠腰髓中的变化

目的观察小胶质细胞在SOD1-G93A转基因小鼠不同时期腰髓中的变化,探讨小胶质细胞活化与肌萎缩侧索硬化(ALS)疾病进展的关系。方法以国际公认的SOD1-G93A转基因小鼠,应用免疫组化、激光共聚焦显微镜及Westernblot方法 ,分别观察SOD1-G93A转基因小鼠症状前期、症状期、终末期及其同窝对照腰髓小胶质细胞形态数量及特异性标记物表达的变化情况。结果 SOD1-G93A转基因小鼠腰髓在症状前期(60天)已出现小胶质细胞数量增多及特异性标记物CD11b表达升高,随病程进展,症状期小胶质细胞增多、活化显著,终末期达高峰。结论随SOD1-G93A转基因小鼠病程进展小胶质细胞增生明显,小胶质细胞的活化可能参与ALS运动神经元损伤。     

GFP转基因小鼠神经干细胞移植治疗大鼠帕金森病的实验研究

目的观察GFP(绿色荧光蛋白)转基因小鼠胚胎神经干细胞植入帕金森病大鼠纹状体后的存活、分化情况及治疗作用。方法建立PD模型大鼠及体外培养神经干细胞,然后将GFP转基因小鼠神经干细胞定向植入帕金森病大鼠毁损侧纹状体内,于移植后不同时间诱发旋转行为,并与对照组相比,观察症状的改善,并用酪氨酸羟化酶(TH)免疫组织化学染色方法检测移植GFP转基因小鼠神经干细胞的存活及分化状况。结果 GFP转基因小鼠神经干细胞脑内移植后,帕金森病大鼠的旋转行为明显改善。移植后2至4周时可检测到成片或散在的TH免疫阳性细胞。结论 GFP转基因小鼠神经干细胞移植至帕金森病大鼠纹状体后,可分化为多巴胺能神经元并能改善旋转症状。     

SOD1-G93A小鼠中枢神经系统SIRT1的变化及白藜芦醇对其的影响

目的观察SOD1-G93A小鼠运动皮质和腰髓中SIRT1的变化以及白藜芦醇对SIRT1的影响。方法利用SOD1-G93A小鼠及其野生型小鼠作为实验对象,分别检测随着疾病进展小鼠神经系统中SIRT1表达的动态变化及给予白藜芦醇后SIRT1的变化。结果随着ALS疾病进展,症状早期及终末期SIRT1表达增多,而给予白藜芦醇后,SIRT1表达无明显变化,给予溶剂后SIRT1表达增多。结论随着疾病进展,SOD1-G9A小鼠运动皮质与腰髓中SIRT1的表达逐渐增多;白藜芦醇对SIRT1未起到激活作用,白藜芦醇在SOD1-G93A小鼠模型中有无有益作用尚不能定论。     

用显微注射法建立转bcl-x1基因小鼠

建立转bcl-x1基因小鼠,继而传代建系,用于缺血性脑血管疾病的研究.采用显微注射法,将人bcl-x1基因注入昆明小白鼠受精卵获得子代鼠,然后作PCR,Southern-blot,mRNA,Western-blot检测以获得阳性鼠.实验中注射受精卵l 654枚,移植卵数1 448枚,受体鼠49只,怀孕鼠7只,子代鼠13只,整合数4只并均有表达,植入受精卵的存活率83%,受精卵的总存活率0.78%,移植鼠的怀孕率14.3%,整合效率30.7%,总有效率为0.24%.初步获得了转bcl-x1基因小鼠.     

Expression of DeltaNp73 in hippocampus of APP/PS1 transgenic mice following GFP-BMSCs transplantation

Abstract

Objective: To study the effect of hippocampal bone marrow stromal cells (GFP-BMSCs) transplantation on spatial memory and DeltaNp73 expression in APP/PS1 transgenic mice.

Methods: Twelve APP/PS1 transgenic mice randomly received either 10 μl GFP-BMSCs suspension in medium (GFP-BMSCs transplantation group) or 10 μl complete medium (sham-operated group). Learning and memory function of mice in both groups were observed and tested in Morris water maze experiment at 2 weeks after surgery. Senile plaques and DeltaNp73 protein in hippocampuses were determined by immunohistochemistry and western blot at 3 weeks after surgery, respectively.

Results: APP/PS1 mice treated with BMSCs performed significantly better on the water maze test than those in sham-operated group (P<0·05). Immunohistochemistry showed that GFP-BMSCs distributed uniformly and the number of Alzheimer’s senile plaques reduced after transplantation. Western blot showed that quantified DeltaNp73 protein expression was significantly higher in BMSCs transplantation group when compared with sham-operated group (P<0·01).

Conclusions: Our results suggest that BMSCs transplatation could retard Alzheimer’s disease (AD) like pathology and upregulate DeltaNp73 expression in hippocampuses of APP/PS1 transgenic mice. GFP-BMSCs transplantation will be a potential treatment for AD.     

Mitochondrial changes in motor neurons of homozygotes of leucine 126 TT deletion SOD1 transgenic mice

We investigated the time course of ultrastructural changes of mitochondria in the spinal cord of homozygotes of Leu126TTdel SOD1 (superoxide dismutase 1) with FLAG (signal sequence at the C‐terminal protein) transgenic mice (DF‐homo). Non‐Tg mice and wild‐type human SOD1 with FLAG epitope transgenic mice (WF) were investigated as controls for non‐onset Tg mice. Expansion and vacuolation of the mitochondrial matrix was exhibited in motor neurons in the anterior horns of DF‐homo Tg mice at the presymptomatic stage. Such mitochondrial degeneration became severe at the postsymptomatic stage. In contrast, expansion of the mitochondrial inner‐membrane space was not evident even at the terminal stage. Microvacuoles of cytoplasm and fibrillar inclusions were rarely shown from the early symptomatic stage. WF mice showed expansion and vacuolation of the mitochondrial inner membrane space at old age. Non‐Tgs showed no obvious change in mitochondria. Gold‐labeled human SOD1 immunoreactivity showed small amount of gold deposits in the vacuolated mitochondria. These results suggest that the expansion and vacuolation of mitochondrial matrix in the spinal cord of DF‐homo transgenic mice is the first pathological change, but that it is not directly caused by the aggregation of an abnormal human SOD1 protein in intermembrane space of mitochondria.     

A novel dopamine transporter transgenic mouse line for identification and purification of midbrain dopaminergic neurons reveals midbrain heterogeneity

Midbrain dopaminergic (DAergic) neurons are a heterogeneous cell group, composed of functionally distinct cell populations projecting to the basal ganglia, prefrontal cortex and limbic system. Despite their functional significance, the midbrain population of DAergic neurons is sparse, constituting only 20 000–30 000 neurons in mice, and development of novel tools to identify these cells is warranted. Here, a bacterial artificial chromosome mouse line [Dat1‐enhanced green fluorescent protein (eGFP)] from the Gene Expression Nervous System Atlas (GENSAT) that expresses eGFP under control of the dopamine transporter (DAT) promoter was characterized. Confocal microscopy analysis of brain sections showed strong eGFP signal reporter in midbrain regions and striatal terminals that co‐localized with the DAergic markers DAT and tyrosine hydroxylase (TH). Thorough quantification of co‐localization of the eGFP reporter signal with DAT and TH in the ventral midbrain showed that a vast majority of eGFP‐expressing neurons are DAergic. Importantly, expression profiles also revealed DAergic heterogeneity when comparing substantia nigra and ventral tegmental area. Dat1‐eGFP mice showed neither change in synaptosomal DA uptake nor altered levels of DAT and TH in both striatum and midbrain. No behavioural difference between Dat1‐eGFP and wild‐type was found, suggesting that the strain is not aberrant. Finally, cell populations highly enriched in DAergic neurons can be obtained from postnatal mice by fluorescence‐activated cell sorting and the sorted neurons can be cultured in vitro. The current investigation demonstrates that eGFP expression in this mouse line is selective for DAergic neurons, suggesting that the Dat1‐eGFP mouse strain constitutes a promising tool for delineating new aspects of DA biology.     

Elevated UTP and CTP content in cultured neurons from HPRT-deficient transgenic mice

Hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8.; HPRT) catalyzes the salvage synthesis of inosine-5′-monophosphate (IMP) and guanosine-5′-monophosphate (GMP) from the purine bases hypoxanthine and guanine, respectively. Complete deficiency of HPRT activity is associated with the Lesch-Nyhan syndrome (LNS), characterized by excessive purine production and severe neurological manifestations. The etiology of the metabolic consequences of HPRT deficiency is clarified, but that of the neurological manifestations is not yet understood. HPRT-deficient mice represent an experimental animal model of LNS. In search for a possible metabolic abnormality in LNS brains, connecting the neurological deficit to HPRT deficiency, the purine and pyrimidine nucleotide content of cultured neurons, prepared from HPRT-deficient transgenic mice, was now determined. The HPRT-deficient neuronal cultures exhibited a significantly elevated content of the pyrimidine nucleotides UTP (1.33-fold the normal level, p=0.0002) and CTP (1.28-fold the normal level, p=0.02), but normal content of the purine nucleotides ATP and GTP. This abnormality in neuronal pyrimidine nucleotide content may be associated with the pathophysiology of the neurological deficit in LNS.     

Physiological and induced neuronal death are not affected in NSE-bax transgenic mice

Bax, a family member of the survival protein Bcl-2, is expressed in the nervous system during development and throughout adulthood. Bax deficiency has been demonstrated to prevent developmental and trophic factor deprivation-induced neuronal death. To further clarify the role of Bax in naturally occurring neuronal death and in neuronal death following apoptotic stimuli, we generated several lines of transgenic mice expressing the human Bax protein specifically in neurons, under the control of the neuron-specific enolase promoter. Transgene expression was first detected around E10.5 and E12.5, depending on the transgenic line. The total number of ganglion cells in the retina and of pyramidal cells in the hippocampus, both expressing the transgene, was similar in control and transgenic mice. In addition, in our model system, Bax overexpression did not appear to influence the in vitro survival of sensory neurons isolated from dorsal root ganglia after nerve grwoth factor (NFG) deprivation or the apoptotic death of motor neurons following axotomy. J. Neurosci. Res. 52:247–259, 1998. © 1998 Wiley-Liss, Inc.     

Differential neuropathological alterations in transgenic mice expressing alpha-synuclein from the platelet-derived growth factor and Thy-1 promoters

Accumulation of alpha-synuclein has been associated with neurodegenerative disorders, such as Lewy body disease and multiple system atrophy. We previously showed that expression of wild-type human alpha-synuclein in transgenic mice results in motor and dopaminergic deficits associated with inclusion formation. To determine whether different levels of human alpha-synuclein expression from distinct promoters might result in neuropathology mimicking other synucleopathies, we compared patterns of human alpha-synuclein accumulation in the brains of transgenic mice expressing this molecule from the murine Thy-1 and platelet-derived growth factor (PDGF) promoters. In murine Thy-1-human alpha-synuclein transgenic mice, this protein accumulated in synapses and neurons throughout the brain, including the thalamus, basal ganglia, substantia nigra, and brainstem. Expression of human alpha-synuclein from the PDGF promoter resulted in accumulation in synapses of the neocortex, limbic system, and olfactory regions as well as formation of inclusion bodies in neurons in deeper layers of the neocortex. Furthermore, one of the intermediate expressor lines (line M) displayed human alpha-synuclein expression in glial cells mimicking some features of multiple system atrophy. These results show a more widespread accumulation of human alpha-synuclein in transgenic mouse brains. Taken together, these studies support the contention that human alpha-synuclein expression in transgenic mice might mimic some neuropathological alterations observed in Lewy body disease and other synucleopathies, such as multiple system atrophy.     

Neurons induce GFAP gene promoter of cultured astrocytes from transgenic mice

In order to investigate the influence of neuron‐glia interaction on astrocyte differentiation, we used a transgenic mouse bearing part of the gene promoter of the astrocytic maturation marker GFAP linked to the β‐galactosidase (β‐gal) reporter gene. Addition of embryonic cerebral hemisphere (CH) neurons to transgenic CH astrocyte monolayers increased by 50–60% β‐gal positive cell number. Such event was dependent on the brain regional origin of the neurons and was followed by an arrest of astrocytes from the cell cycle and induction of glial differentiation. Time‐course assays demonstrated that maximum effect was observed after 24 h of coculture. Addition of conditioned medium (CM) derived from CH neurons also increased β‐gal positive CH astrocytic cell number. However, such CM had no effect on midbrain and cerebellum astroglia. Together, these data suggest that neurons secrete brain region‐specific soluble factors which induce GFAP gene promoter, as measured by β‐gal expression, thus suggesting that neuron‐glia interaction might induce the astrocytic differentiation program. GLIA 26:97–108, 1999. © 1999 Wiley‐Liss, Inc.     

Gait analysis detects early changes in transgenic SOD1(G93A) mice

The effective treatment or cure of motoneuron disease will require understanding the disease processes that precede irreversible cell loss. To study these early stages, and to evaluate potential treatments in relevant animal models, requires a sensitive functional assay. To this end, we sought to determine whether the gait pattern of SOD1 transgenic mice changed prior to overt symptoms. Using a simplified video-based approach we compared the treadmill gait of C57BL/6J and B6.SOD1 transgenic mice at 8 and 10 weeks of age. B6.SOD1 mice had significantly longer stride and stance times than controls by 8 weeks. Consistent with disease progression, hindpaw measures of B6.SOD1 mice showed larger changes than front paws. Differences between control and B6.SOD1 mice increased at 10 weeks, but only because repeat testing caused habituation in control mice to a greater extent than in B6.SOD1 mice. Together the results demonstrate that simplified gait analysis is sensitive to early processes of motor system disease in mice.     

Direct isolation of committed neuronal progenitor cells from transgenic mice coexpressing spectrally distinct fluorescent proteins regulated by stage-specific neural promoters

Many tissues arise from pluripotent stem cells through cell-type specification and maturation. In the bone marrow, primitive stem cells generate all the different types of blood cells via the sequential differentiation of increasingly committed progenitor cells. Cell-surface markers that clearly distinguish stem cells, restricted progenitors, and differentiated progeny have enabled researchers to isolate these cells and to study the regulatory mechanisms of hematopoiesis. Neuronal differentiation appears to involve similar mechanisms. However, neural progenitor cells that are restricted to a neuronal fate have not been characterized in vivo, because specific cell-surface markers are not available. We have developed an alternative strategy to identify and isolate neuronal progenitor cells based on dual-color fluorescent proteins. To identify and isolate directly progenitor cells from brain tissue without the need for either transfection or intervening cell culture, we established lines of transgenic mice bearing fluorescent transgenes regulated by neural promoters. One set of transgenic lines expressed enhanced yellow fluorescent protein (EYFP) in neuronal progenitor cells and neurons under the control of the Talpha1 alpha-tubulin promoter. Another line expressed enhanced green fluorescent protein (EGFP) in immature neural cells under the control of the enhancer/promoter elements of the nestin gene. By crossing these lines we obtained mice expressing both transgenes. To isolate neuronal progenitor cells directly from the developing brain, we used flow cytometry, selecting cells that expressed EGFP and EYFP simultaneously. We expect this strategy to provide valuable material with which to study the mechanisms of neurogenesis and to develop cell-based therapies for neurological disorders.     

The use of flow cytometry to evaluate temporal changes in inflammatory cells following focal cerebral ischemia in mice

Recent studies indicate that inflammation following cerebral ischemia contributes to neuronal damage. The local activation of resident cells and efficient recruitment of leukocytes into the central nervous system are critical steps in this inflammatory process. Here we describe studies using flow cytometry to examine the temporal pattern of inflammatory cell activation and infiltration following transient middle cerebral artery occlusion (MCAO) in mice. We found an increase in activated microglia/macrophages as early as 18 h post occlusion, which peaked at 48 h and remained abundant at 96 h post occlusion. Neutrophils were significantly increased by 48 h and remained elevated at 96 h post occlusion. T lymphocytes were increased relatively late (72 and 96 h) post occlusion. The flow cytometry data correlate well both quantitatively and qualitatively with immunohistochemistry analysis performed on the same mice. The present study demonstrates the power of flow cytometry in analyzing the inflammatory process following cerebral ischemia and offers temporal information on the cellular changes in mice following transient MCAO.