牛磺酸对高糖培养下视网膜Mü ller细胞GFAP和TAUT表达的影响

目的:通过检测高糖培养条件下视网膜Müller细胞神经纤维酸性蛋白(glial fibrillary acid protein,GFAP)和牛磺酸转运蛋白(taurine transporter,TAUT)的表达变化,观察葡萄糖对Müller细胞牛磺酸(taurine)转运功能的影响,探讨牛磺酸对早期糖尿病视网膜病(DR)可能的保护作用。方法:高糖培养大鼠视网膜Mǜller细胞,用免疫细胞荧光化学双染色、Western blotting技术检测不同浓度牛磺酸干预下Müller细胞GFAP及TAUT的蛋白表达。结果:高糖可引起Müller细胞GFAP表达增强,TAUT表达减弱;牛磺酸可减弱高糖引起的Müller细胞GFAP表达增强,TAUT在0．1mmol/L～10mmol/L的牛磺酸干预后表达增强。结论:牛磺酸可以抑制高糖导致的Müller细胞功能改变。     

无蹼壁虎消化道5-羟色胺细胞的免疫组织化学定位

目的研究无蹼壁虎(Gekkoswinhonis)消化道内5-HT免疫反应阳性内分泌细胞的分布以及形态。方法应用显示5-HT的免疫组织化学方法。结果5-HT阳性细胞在无蹼壁虎消化道各段均有分布,其中以十二指肠部位分布密度最多,食道和直肠其次,回肠部位分布密度最低。消化道各段5-HT细胞形态多样,有圆形、椭圆形、梭形、不规则形,其中梭形细胞多具有胞突。结论无蹼壁虎的消化道5-HT细胞的分布、形态与其功能相适应。     

牛磺酸对高糖培养下视网膜Mü ller细胞GFAP和TAUT表达的影响

目的：通过检测高糖培养条件下视网膜Mü ller细胞神经纤维酸性蛋白（glial fibrillary acid protein,GFAP）和牛磺酸转运蛋白（taurine transporter,TAUT）的表达变化,观察葡萄糖对Mü ller细胞牛磺酸（taurine）转运功能的影响,探讨牛磺酸对早期糖尿病视网膜病（DR）可能的保护作用.方法：高糖培养大鼠视网膜Mü ller细胞,用免疫细胞荧光化学双染色、Western blotting技术检测不同浓度牛磺酸干预下Mü ller细胞GFAP及TAUT的蛋白表达.结果：高糖可引起Mü ller细胞GFAP表达增强,TAUT表达减弱;牛磺酸可减弱高糖引起的Mü ller细胞GFAP表达增强,TAUT在0.1mmol/L～10 mmo1/L的牛磺酸干预后表达增强.结论：牛磺酸可以抑制高糖导致的Müller细胞功能改变.     

猫小脑髓质胶质反应的年龄相关性变化

探讨青年猫和老年猫小脑髓质中胶质反应的年龄相关性变化及其意义。用改良的Holzer结晶紫染色显示所有胶质细胞,GFAP(胶质纤维酸性蛋白)免疫染色显示星形胶质细胞。光镜下对青年猫与老年猫小脑髓质中胶质细胞和GFAP免疫阳性(GFAP-IR)星形胶质细胞进行形态学观察和定量研究。与青年猫比较,老年猫小脑髓质中胶质细胞和GFAP-IR细胞密度均显著增加(P<0.01),胞体较大;GFAP阳性细胞阳性反应较强,突起稠密;星形胶质细胞占胶质细胞总数比例增加。这表明小脑髓质中胶质细胞随年龄增长明显增生,尤其星形胶质细胞具有明显的年龄相关性活动增强。提示胶质细胞及星形胶质细胞的增生可能对衰老的神经纤维起保护作用;星形胶质细胞对衰老较敏感。     

缺氧对鼠视网膜Müller细胞GLAST和GS表达及功能的影响

研究了缺氧对鼠视网膜Müller细胞谷氨酸转运体(L-glutamate/L-aspartate transporter,GLAST)和谷氨酰胺合成酶(glutamine synthetase,GS)表达的影响,及对谷氨酸摄取的作用.采用出生3～7天的小鼠视网膜组织进行Müller细胞培养,采用125μmol/L的氯化钴(CoCl2)溶液分别进行缺氧干预6、12、24、48和72 h,不加CoCl2溶液培养的Müller细胞为正常对照.采用RT-PCR法、Western blot法和免疫细胞化学染色法检测GLAST和GS的表达,并检测谷氨酸摄取及细胞凋亡情况.结果显示,缺氧早期GLAST表达较正常对照组增强(P<0.001),CoCl2溶液干预12 h后达到最强(P<0.05),之后逐渐降低.CoCl2溶液干预72 h后GLAST表达与正常对照组相比无明显差异(P>0.05).而缺氧也使GS的表达较正常对照组增加(P<0.001),CoCl2溶液干预48 h后GS表达最强(P<0.001),之后开始下降.缺氧促进Müller细胞对谷氨酸的摄取,CoCl2溶液干预48 h后L-[3,4-3H]-谷氨酸的摄取量最大(P<0.005),之后开始下降.CoCl2溶液干预后,Müller细胞死亡数较正常对照组无明显差异(P>0.05).结果表明,在一定时间范围内缺氧能够增强Müller细胞GLAST及GS的表达,增加谷氨酸的摄取.但持续缺氧最终会引起Müller细胞功能失代偿,从而导致谷氨酸的代谢能力降低.     

EPO修饰增强Muller细胞对RCS大鼠视网膜变性的干预效果

目的：研究人源促红细胞生成素（hEPO）修饰的Müller（hEPO-Müller）细胞对视网膜退行性病变大鼠的干预作用。方法通过质粒转染法构建hEPO和GFP的Müller细胞稳转株（hEPO-Müller和GFP-Müller）;以体外共培养和体内细胞移植为研究体系,利用RT-PCR和冰冻切片及免疫荧光染色的方法检测hEPO-Müller对RCS大鼠视网膜退行性病变的干预作用。内核层与外核层厚度比较采用t检验。结果本实验成功构建了hEPO-Müller和GFP-Müller细胞系。将RCS大鼠的视网膜组织剥离并在体外不同条件下培养两周后测定视网膜各核层厚度发现,与对照细胞裂解液共培养组的内核层（15.94±1.77）μm和外核层（24.81±3.03）μm的厚度相比较,两核层的厚度分别在hEPO组为（23.03±3.29）μm,（33.92±7.59）μm（P〈0.05）;Müller 组为（24.81±2.02）μm,（32.15±3.03）μm（P〈0.05）;hEPO-Müller组为（32.40±8.35）μm,（40.25±3.29）μm（n=3, P〈0.01）;以hEPO-Müller组厚度增加最为显著（P〈0.05）。提示EPO和Müller细胞对视网膜变性都有干预作用且两者可以叠加。将hEPO-Müller和GFP-Müller分别移植到RCS大鼠的视网膜下腔,四周后取视网膜进行冰冻切片检测,染色结果显示,细胞移植后有更多的外核层细胞存活,且同样也是hEPO-Müller组的外核层细胞更多。此外,Müller移植并不会促进视网膜的胶质化。结论移植Müller细胞可以减缓RCS大鼠视网膜变性,而经hEPO修饰的Müller细胞对视网膜变性有更好的干预作用。因此,Müller细胞可以作为一种供体细胞兼携带hEPO等营养因子的载体用于视网膜变性的治疗。     

波形蛋白在不同年龄大鼠脊髓后角表达

目的:检测波形蛋白(Vimentin)在不同年龄大鼠脊髓后角的表达,探讨Vimentin在大鼠脊髓成熟和衰老过程中的表达变化.方法:对新生(7天龄)、成年(2月龄)、老年(24月龄)大鼠脊髓进行Vimentin和胶质纤维酸性蛋白(GFAP)免疫荧光双标染色,并进行荧光强度的定量分析.结果:新生组Vimentin阳性产物荧光强度(59.73±9.92)较强,成年组Vimentin阳性产物荧光强度(43.26±7.99)较新生组弱,老年组Vimentin阳性产物荧光强度(40.65±6.84)较成年组弱,两组间差异均有统计学意义(P＜0.01).结论:脊髓后角新生组、成年组、老年组Vimentin的表达随着年龄的增长而降低.     

猫视网膜年龄相关的形态学变化

取老年猫(12龄,3～3．5kg)和青年猫(1～3龄,2～2．5kg)各4只的视网膜,经4％多聚甲醛处理后,用H．E．染色以显示视网膜结构,Nissl染色显示神经节细胞,免疫组织化学ABC法染色以显示星形胶质细胞特征性标志物胶质纤维酸性蛋白(GFAP)的阳性反应细胞的分布。显微镜下观察测量视网膜厚度,计数神经节细胞、GFAP免疫反应阳性细胞数。与青年猫比较,老年猫视网膜总厚度以及外核层、外网状层、内核层和内网状层厚度均显著减小;神经节细胞层的细胞密度显著下降;GFAP免疫反应阳性细胞显著增加,GFAP阳性细胞阳性反应强,胞体明显膨胀,突起稠密粗大。推测在衰老过程中视网膜细胞有神经元丢失现象,可能是造成视觉功能衰退的重要原因之一;视网膜星形胶质细胞的功能增强可能会延缓衰老。     

Müller细胞在视网膜绿光损伤模型中的激活反应

目的研究Müller细胞在大鼠视网膜绿光损伤模型中的激活反应。方法 72只出生后8周(约230～280g)的成年雄性Sprague-Dawley大鼠随机分9组。一组作为正常对照,另8组暗适应24 h后置于波长为(530±10)nm的LED灯光箱中照射3 h,并分别于暗恢复3、6、12 h及1、2、3、7、15 d取眼球,光学显微镜下观察同一定位处视网膜组织形态、检测(TUNEL)凋亡细胞、免疫组织化学染色及蛋白免疫印迹分析。结果光损伤后光感受器内外节变短,外核层变薄,细胞排列紊乱;细胞凋亡出现在外核层,暗恢复3 h出现,3 d时达到高峰,7 d时消失;胶质细胞纤维酸性蛋白(glial fibrillary acidic protein,GFAP)表达量于暗恢复12 h开始升高,随暗恢复时间延长逐渐升高;谷氨酰胺合成酶(glutaminesynthetase,GS)总表达量未见明显改变,但可见蛋白一过性重分布,表达部位由内核层移至外核层。pSTAT3蛋白表达量于损伤后12 h出现一过性升高。结论绿光损伤视网膜激活Müller细胞,pSTAT3可能参与了此激活过程。     

光周期影响MT_1-R在无蹼壁虎室旁核的节律性表达(英文)

目的研究不同光周期下,MT1-R在无蹼壁虎室旁核(PVN)的节律性(昼夜节律和季节节律)表达变化。方法运用了免疫印迹、免疫组织化学和形态学计数法。结果 (1)免疫印迹结果显示MT1-R蛋白分子量为37KD,MT1-R阳性细胞主要分布在下丘脑室旁核,且有少量阳性纤维;(2)在无蹼壁虎的活动期(夏季),各光周期(DD、DL和LL)下MT1-R阳性细胞在PVN均呈明显的昼夜节律变化(P0.0001),DD、LL较DL均有时相变化;(3)在冬眠期(冬季),DL光周期下MT1-R阳性细胞在PVN无明显的昼夜节律变化(P=0.005),DD和LL光周期下MT1-R阳性细胞在PVN呈明显的昼夜节律变化(P0.0001),DD、LL较DL均有时相变化;(4)各光周期(DD、DL和LL)下MT1-R阳性细胞在PVN均呈明显的季节性节律变化(P0.0001),活动期(夏季)的MT1-R阳性细胞数较冬眠期(冬季)明显多(P0.0001),DD和LL在活动期、冬眠期的节律图形相似。结论 MT1-R在无蹼壁虎室旁核的表达有明显的节律性(昼夜节律和季节节律),不同光周期对MT1-R的节律性表达有影响,但其图形基本相似。提示光周期可能通过启动"内源性节律钟"影响MT1-R在无蹼壁虎室旁核的节律性表达,其可能调控MT1-R蛋白的表达量。     

Sonic hedgehog promotes stem-cell potential of Müller glia in the mammalian retina

Müller glia have been demonstrated to display stem-cell properties after retinal damage. Here, we report this potential can be regulated by Sonic hedgehog (Shh) signaling. Shh can stimulate proliferation of Müller glia through its receptor and target gene expressed on them, furthermore, Shh-treated Müller glia are induced to dedifferentiate by expressing progenitor-specific markers, and then adopt cell fate of rod photoreceptor. Inhibition of signaling by cyclopamine inhibits proliferation and dedifferentiation. Intraocular injection of Shh promotes Müller glia activation in the photoreceptor-damaged retina, Shh also enhances neurogenic potential by producing more rhodopsin-positive photoreceptors from Müller glia-derived cells. Together, these results provide evidences that Müller glia act as potential stem cells in mammalian retina, Shh may have therapeutic effects on these cells for promoting the regeneration of retinal neurons.     

Regional adaptation of Müller cells in the chick retina. A Golgi and electron microscopical study

We report the morphological differences of Müller cells in relation to their topography, using the Golgi method. Müller cells in the central retina are long and slender, with numerous inner prolongations. In the peripheral retina, the morphology of the Müller cells adapts to the reduced thickness of the retinal layers. In this zone, they are short and have thick inner prolongations which end in a large foot in the internal limiting membrane. In the optic disc margin, Müller cells have a particular morphology characterized by thick, arched prolongations that in general form a glial network between the retina and optic nerve. The ultrastructure of these cells is also described. The results are discussed with respect to the nature of Müller cells.     

Role of Müller glia in neuroprotection and regeneration in the retina

Glial cells are thought to protect neurons from various neurological insults. When there is injury to retina, Müller cells, which are the predominant glial element in the retina, undergo significant morphological, cellular and molecular changes. Some of these changes reflect Müller cell involvement in protecting the retina from further damage. Müller cells express growth factors, neurotransmitter transporters and antioxidant agents that could have an important role in preventing excitotoxic damage to retinal neurons. Moreover, Müller cells contact to endothelial cells to facilitate the neovascularization process during hypoxic conditions. Finally, recent studies have pointed to a role of Müller cells in retina regeneration after damage, dedifferentiating to progenitor cells and then giving rise to different neuronal cell types. In this article we will review the role of Müller glia in neuroprotection and regeneration after damage in the retina.     

Immunohistochemical Localization of Glycogen Synthase and GSK3β: Control of Glycogen Content in Retina

Glycogen has an important role in energy handling in several brain regions. In the brain, glycogen is localized in astrocytes and its role in several normal and pathological processes has been described, whereas in the retina, glycogen metabolism has been scarcely investigated. The enzyme glycogen phosphorylase has been located in retinal Müller cells; however the cellular location of glycogen synthase (GS) and its regulatory partner, glycogen synthase kinase 3β (GSK3β), has not been investigated. Our aim was to localize these enzymes in the rat retina by immunofluorescence techniques. We found both GS and GSK3β in Müller cells in the synaptic layers, and within the inner segments of photoreceptor cells. The presence of these enzymes in Müller cells suggests that glycogen could be regulated within the retina as in other tissues. Indeed, we showed that glycogen content in the whole retina in vitro was increased by high glucose concentrations, glutamate, and insulin. In contrast, retina glycogen levels were not modified by norepinephrine nor by depolarization with high KCl concentrations. Insulin also induced an increase in glycogen content in cultured Müller cells. The effect of insulin in both, whole retina and cultured Müller cells was blocked by inhibitors of phosphatidyl-inositol 3-kinase, strongly suggesting that glycogen content in retina is modulated by the insulin signaling pathway. The expression of GS and GSK3β in the synaptic layers and photoreceptor cells suggests an important role of GSK3β regulating glycogen synthase in neurons, which opens multiple feasible roles of insulin within the retina.     

Neural stem cell properties of Müller glia in the mammalian retina: regulation by Notch and Wnt signaling

The retina in adult mammals, unlike those in lower vertebrates such as fish and amphibians, is not known to support neurogenesis. However, when injured, the adult mammalian retina displays neurogenic changes, raising the possibility that neurogenic potential may be evolutionarily conserved and could be exploited for regenerative therapy. Here, we show that Müller cells, when retrospectively enriched from the normal retina, like their radial glial counterparts in the central nervous system (CNS), display cardinal features of neural stem cells (NSCs), i.e., they self-renew and generate all three basic cell types of the CNS. In addition, they possess the potential to generate retinal neurons, both in vitro and in vivo. We also provide direct evidence, by transplanting prospectively enriched injury-activated Müller cells into normal eye, that Müller cells have neurogenic potential and can generate retinal neurons, confirming a hypothesis, first proposed in lower vertebrates. This potential is likely due to the NSC nature of Müller cells that remains dormant under the constraint of non-neurogenic environment of the adult normal retina. Additionally, we demonstrate that the mechanism of activating the dormant stem cell properties in Müller cells involves Wnt and Notch pathways. Together, these results identify Müller cells as latent NSCs in the mammalian retina and hence, may serve as a potential target for cellular manipulation for treating retinal degeneration.     

Mueiller细胞与视网膜功能

Ｍｕｅｌｌｅｒ细胞是视网膜中的主要胶质细胞。除了一般的支持和营养作用外,近年的许多研究表明,在Ｍｕｅｌｌｅｒ细胞和视网膜视风膜神经元之间在着双向的通讯,它们可以直接通过改变细胞外空间神经活性物质的浓度或间接（通过控制神经元的微环境）调制制神经元活动,因此在视网膜功能中起着重要的作用。     

Glial cell fate specification modulated by the bHLH gene Hes5 in mouse retina

Neurons and glial cells differentiate from common precursors. Whereas the gene glial cells missing (gcm) determines the glial fate in Drosophila, current data about the expression patterns suggest that, in mammals, gcm homologues are unlikely to regulate gliogenesis. Here, we found that, in mouse retina, the bHLH gene Hes5 was specifically expressed by differentiating Müller glial cells and that misexpression of Hes5 with recombinant retrovirus significantly increased the population of glial cells at the expense of neurons. Conversely, Hes5-deficient retina showed 30-40% decrease of Müller glial cell number without affecting cell survival. These results indicate that Hes5 modulates glial cell fate specification in mouse retina.     

低亲和性神经营养素受体p75在人胚胎视网膜中的表达

p75神经营养素受体在视网膜的发育以及再生过程中发挥着重要的作用,而在人类视网膜中的分布状况尚未被研究. 利用免疫组织化学方法,在光镜水平下确定了p75在人胚胎发育5、6和7个月的视网膜中的分布情况. 在视网膜神经节细胞层出现最强的p75免疫阳性反应,在其他各层也有较弱的免疫阳性反应. 在胚胎6、7月的视网膜中,主要由Müller细胞的终足构成的内界膜上出现了比较强的p75表达. p75在人胚胎视网膜中的分布情况与大鼠视网膜中很类似,主要表达在Müller细胞, 在神经节细胞上也可能有表达.