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。     

猫小脑皮质浦肯野细胞超微结构的年龄相关变化

目的比较观察青年猫（1-3岁）和老年猫（12-13岁）小脑皮质浦肯野细胞（Purkinje cell,PC）的超微结构,探讨其年龄相关变化的生理意义。方法常规电镜包埋、切片、染色,透射电镜下观察并拍照。结果老年组PC粗面内质网碎裂,核糖体解离;线粒体膨解,嵴减少;高尔基复合体扁平囊扩张,极性退化;脂褐素聚积;膜性髓样结构与空泡变性出现;核膜内陷,染色质固缩;生物膜系统结构破坏等。结论衰老过程中细胞器结构退化可能影响老年PC物质合成、能量供应、信息传递及神经元的结构稳定,导致衰老PC死亡,推测与老年个体运动调节和运动学习等小脑功能退化有重要联系。     

猫视神经年龄相关的形态学变化

对4只青年猫(1-3龄)和4只老年猫(10-13龄)视神经进行形态计量比较研究。取两个年龄组的颅内相应部分视神经进行横向连续切片,H.E染色于光镜下观察其基本结构;相邻切片进行结晶紫染色显示胶质细胞;神经丝蛋白(NF)免疫染色显示视神经纤维,胶质纤维酸性蛋白(GFAP)免疫染色显示星形胶质细胞(AS),对实验结果进行统计学分析并绘制纤维直径谱。与青年猫相比,老年猫视神经外膜厚度、直径、面积均显著增加,视神经纤维的密度和数量显著下降,且以视神经中央部纤维密度下降最显著;纤维直径谱分析结果显示,青、老年猫纤维直径分布范围相似,但老年猫的峰直径及纤维平均直径比青年猫的显著减小;另外,老年猫视神经束中的星形胶质细胞明显膨大,胶质细胞密度以及星形胶质细胞占胶质细胞总数的百分比均显著增加。结果表明:在衰老过程中视神经纤维出现明显的丢失现象,纤维平均直径显著减小使其对视觉信息的传导速度减慢,这可能是导致老年个体视觉分析速度下降的重要原因;老年个体视神经束内胶质细胞活动增强可能对维持视神经纤维形态、功能或延缓视神经进一步衰老起保护作用     

猫视神经中S100蛋白表达的年龄相关变化

比较老年猫和青年猫视神经S100蛋白表达及胶质细胞的年龄相关变化,探讨其可能的生理作用.取老年猫(10～13龄)和青年猫(1～3龄)各4只的颅内视神经相应部分作组织切片,用免疫组织化学ABC法标记S100免疫阳性(S100～IR)细胞,Marsland-Gless染色显示胶质细胞.光镜下采用图像分析系统计数视神经中S100-IR细胞密度、胶质细胞密度及阳性反应灰度值.视神经中棕黄色S100-IR细胞分布均匀,Marsland-Gless染色的纤维横断面及胶质细胞均呈棕红色.与青年猫相比,老年猫视神经中胶质细胞密度明显增大;S100-IR细胞密度显著增加(P<0.01),胞体较大,阳性较强(灰度值显著减小,P<0.01);S100-IR细胞在胶质细胞中所占比例亦显著增大.结果表明S100-IR细胞呈明显的年龄相关性增生,这可能对衰老的神经纤维起保护作用.     

多种神经活性物质在幼年猫和鸡视网膜神经...

An improved post-embedding immunocytochemical technique was used to examine the coexistence of multi-neuroactive substances in neurons of young cat and newly hatched chicken retinas. We found that two classical neurotransmitters-glycine (Gly) and r-aminobutyric acid (GABA) and one neuropeptide, neurotensin (NT) were located in the amacrine cells of cat and chicken retinas. Among them, some cells contain Gly and GABA (Gly/GABA AC), some cells contain Gly and NT (Gly/NT AC) or GABA and NT (GABA/NT AC), and the other cells, a few of them contain Gly, GABA and NT (Gly/GABA/NT AC). In addition, two classical neurotransmitters Gly and GABA were also located or coexisted in the horizontal cells of cat retina. These results indicated that the coexistence of two neurotransmitters or one neurotransmitter and one neuropeptide or two neurotransmitters and one neuropeptide was presented in neurons of developing can and chicken retinas.     

猫腰髓白质年龄相关的形态学变化

以青年成年猫(1-3龄,2-2．5 kg)和老年猫(12龄,3-3．5kg)L6段脊髓白质为研究对象,用 神经丝蛋白(NF)免疫染色显示神经纤维,用改良的Holzer结晶紫染色显示所有胶质细胞并用成年动物Golgi 法显示其形态,用胶质纤维酸性蛋白(GFAP)免疫染色显示星形胶质细胞。光镜下对青年猫与老年猫腰髓白质 中神经纤维和胶质细胞进行形态学观察和定量研究。与青年猫相比,老年猫腰髓白质中的神经纤维密度显著下 降(P相似文献   

“反贴”的视网膜

人眼的视网膜主要由3层细胞组成,依次是感光细胞(感觉光线)、双极细胞(分析处理视觉信号)和节细胞(归纳信号并传送至大脑)。理论上说,感光细胞应该朝向光线进入的方向,实际情形却与此相反,所以人的视网膜被认为是"反贴"的,而章鱼眼睛的视网膜被认为是"正贴"的。事实上人的眼睛和章鱼的眼睛在实现清晰成像、血液供应和避免血液对视觉图像的影响的机制完全一致。     

猫嗅球外丛层和僧帽细胞层年龄相关形态学变化

分别用Nissl法及免疫组织化学ABC法标记青、老年猫嗅球中嗅觉二级神经元和外丛层胶质细胞,显微镜下观察其分布并计数,对嗅觉二级神经元胞体直径和外丛层厚度进行测量,比较其年龄相关性变化,研究神经元与胶质细胞之间的关系,探讨老年性嗅觉功能衰退的相关神经机理。结果显示,老年猫嗅觉二级神经元胞体直径和分布密度均有不同程度的显著性下降(P<0.05);外丛层厚度变化不明显(P>0.05);外丛层胶质细胞特别是星形胶质细胞显著性增生(P<0.05)。表明在衰老过程中嗅觉二级神经元有丢失,并呈现功能下降,可能是老年性嗅觉功能衰退的原因之一。同时外丛层胶质细胞增生以进一步保护神经元,延缓其衰老。     

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。     

猫视网膜多巴胺能神经元的形态和发育

Morphology and development of dopaminergic neurons has been studied in the kitten retina, using tyrosine hydroxylase (TH) immunocytochemistry. TH immunoreactive (TH+) cells are already presented in whole amount and sectioned retina at first postnatal day (P1). According to soma size, shape, dendritic process pattern and immunoreactivity, two classes, type I or large dark staining TH+ cells and type II or small light staining TH+ cells are recognized. The TH I cells which consisting of normal placed DA amacrine cells, displaced DA amacrine cells and DA interplex-form-like cells, gradually mature during postnatal development, while TH II cells decrease quickly and through disappear at P30. After eye opening TH I amacrine cells, especially their dendrites develop quickly. The soma diameters increase from 11.8 microns (P1) to 14.2 microns (P30). The dendritic fields increase in size and complexity. At P1 the thick radiating dendrites emerge from the cell body with small or large "spines" and many growth cones. At P13 the dendritic field is markedly enlarged and only a few growth cones can be seen on some stained dendrites. In addition, the dendritic spines are no longer apparent and they are a part of rudimentary rings. By P30 the dendritic plexus of TH+ dendrites and rings in the out most part of IPL, typical of the adult cells, are complete. The influence of light on the development of DA cells after eye opening and the possibility of neurotransmitter changing are discussed.     

Retina stem cells,hopes and obstacles

Retinal degeneration is a major contributor to visual dysfunction worldwide. Although it comprises several eye diseases, loss of retinal pigment epithelial (RPE) and photoreceptor cells are the major contributors to their pathogenesis. Early therapies included diverse treatments, such as provision of anti-vascular endothelial growth factor and many survival and trophic factors that, in some cases, slow down the progression of the degeneration, but do not effectively prevent it. The finding of stem cells (SC) in the eye has led to the proposal of cell replacement strategies for retina degeneration. Therapies using different types of SC, such as retinal progenitor cells (RPCs), embryonic SC, pluripotent SCs (PSCs), induced PSCs (iPSCs), and mesenchymal stromal cells, capable of self-renewal and of differentiating into multiple cell types, have gained ample support. Numerous preclinical studies have assessed transplantation of SC in animal models, with encouraging results. The aim of this work is to revise the different preclinical and clinical approaches, analyzing the SC type used, their efficacy, safety, cell attachment and integration, absence of tumor formation and immunorejection, in order to establish which were the most relevant and successful. In addition, we examine the questions and concerns still open in the field. The data demonstrate the existence of two main approaches, aimed at replacing either RPE cells or photoreceptors. Emerging evidence suggests that RPCs and iPSC are the best candidates, presenting no ethical concerns and a low risk of immunorejection. Clinical trials have already supported the safety and efficacy of SC treatments. Serious concerns are pending, such as the risk of tumor formation, lack of attachment or integration of transplanted cells into host retinas, immunorejection, cell death, and also ethical. However, the amazing progress in the field in the last few years makes it possible to envisage safe and effective treatments to restore vision loss in a near future.     

S100在猫小脑中的分布及其表达的年龄相关性变化

用免疫组织化学ABC法标记S100免疫阳性(S100-IR)细胞,观察S100蛋白在青年猫和老年猫小脑中的分布,探讨其表达的年龄相关变化及意义。光镜下计数颗粒层和髓质中S100-IR细胞密度及浦肯野细胞(PC)层阳性细胞线密度。结果显示,颗粒层和髓质中S100-IR细胞密度较小、分布均匀,PC层阳性细胞相对密集,分子层未见阳性反应;阳性细胞胞浆深染。与青年猫相比,老年猫小脑颗粒层、髓质和PC层中S100-IR细胞密度显著增加(P<0.01),胞体较大,阳性较强。表明S100-IR细胞在小脑中的分布具区域性差异,呈明显的年龄相关性增生,推测其增生对衰老神经元的丢失起保护作用。     

猫初级视皮层内GIu/GABA表达比率的衰老性变化

最近的一些研究结果显示,视皮层内抑制性递质系统作用减弱可能是导致老年性视觉功能衰退的重要因素.是否皮层内兴奋性递质系统亦伴随衰老而发牛改变并影响皮层内神经兴奋与抑制的平衡尚不清楚.为此,利用Nissl染色和免疫组织化学染色方法以及Image-Pro Express图像分析软件对青、老年猫初级视皮层(17区)内各层神经元密度、兴奋性递质谷氨酸免疫反应阳性(Glu-immunoreactive,Glu-IR)神经元密度以及抑制性递质γ-氨基丁酸免疫反应阳性(γ-aminobutyric acid.immunoreactive,GABA-IR)神经元密度进行了统汁分析.结果显示,青、老年猫初级视皮层各层神经元密度均没有明显的年龄性差异(P>0.05);与青年猫相比,老年猫初级视皮层Glu-IR、GABA-IR神经元密度均显著减少(P<0.01),而Glu.IR/GABA.IR神经元密度比率去却显著增大(P<0.01).结果提示,老年猫初级视皮层内兴奋性递质系统作用相对增强,而抑制性递质系统的作用相对减弱,导致皮层内兴奋-抑制平衡关系失调,这可能是引起老年个体视觉功能衰退的重要原因之一.     

Cellular and Subcellular Localization of Hexokinase, Glutamate Dehydrogenase, and Alanine Aminotransferase in the Honeybee Drone Retina

Abstract: Subcellular localization of hexokinase in the honeybee drone retina was examined following fractionation of cell homogenate using differential centrifugation. Nearly all hexokinase activity was found in the cytosolic fraction, following a similar distribution as the cytosolic enzymatic marker, phosphoglycerate kinase. The distribution of enzymatic markers of mitochondria (succinate dehydrogenase, rotenone-insensitive cytochrome c reductase, and adenylate kinase) indicated that the outer mitochondrial membrane was partly damaged, but their distributions were different from that of hexokinase. The activity of hexokinase in purified suspensions of cells was fivefold higher in glial cells than in photoreceptors. This result is consistent with the hypothesis based on quantitative 2-deoxy[³H]glucose autoradiography that only glial cells phosphorylate significant amounts of glucose to glucose-6-phosphate. The activities of alanine aminotransferase and to a lesser extent of glutamate dehydrogenase were higher in the cytosolic than in the mitochondrial fraction. This important cytosolic activity of glutamate dehydrogenase was consistent with the higher activity found in mitochondria-poor glial cells. In conclusion, this distribution of enzymes is consistent with the model of metabolic interactions between glial and photoreceptor cells in the intact bee retina.     

Characterization of Protein Kinase C in Photoreceptor Outer Segments

Abstract: Protein kinase C (PKC) has been implicated in regulating several proteins involved in phototransduction. This contribution characterizes the biochemical and immunological properties of PKC isozyme(s) in the photoreceptor outer segment. Activity measurements revealed that at least 85% of the PKC in this specialized compartment belongs to the subfamily of Ca²⁺-regulated (conventional) PKCs. Of the known Ca²⁺-dependent PKCs, only PKCα was immunodetected by western blot analysis of rod outer segment proteins. However, the ratio of immunoreactivity to enzyme activity for rod outer segment PKC was no more than 40% of that for brain PKC, using antibodies against conventional PKCs. Therefore, at least half the Ca²⁺/lipid-stimulated activity in rod outer segment preparations cannot be accounted for by the known isozymes, suggesting the presence of a previously uncharacterized isozyme. Despite extensive tests using a variety of antibodies against different domains of PKCα, PKCα could not be detected in rod outer segments by immunofluorescence of retinal sections. In summary, our data reveal that most of the PKC in photoreceptor outer segments is of the conventional type and that most, if not all, of this conventional PKC activity comes from a novel isozyme(s).     

Developmentally Regulated Linker Histone H1c Promotes Heterochromatin Condensation and Mediates Structural Integrity of Rod Photoreceptors in Mouse Retina

Mature rod photoreceptor cells contain very small nuclei with tightly condensed heterochromatin. We observed that during mouse rod maturation, the nucleosomal repeat length increases from 190 bp at postnatal day 1 to 206 bp in the adult retina. At the same time, the total level of linker histone H1 increased reaching the ratio of 1.3 molecules of total H1 per nucleosome, mostly via a dramatic increase in H1c. Genetic elimination of the histone H1c gene is functionally compensated by other histone variants. However, retinas in H1c/H1e/H1⁰ triple knock-outs have photoreceptors with bigger nuclei, decreased heterochromatin area, and notable morphological changes suggesting that the process of chromatin condensation and rod cell structural integrity are partly impaired. In triple knock-outs, nuclear chromatin exposed several epigenetic histone modification marks masked in the wild type chromatin. Dramatic changes in exposure of a repressive chromatin mark, H3K9me2, indicate that during development linker histone plays a role in establishing the facultative heterochromatin territory and architecture in the nucleus. During retina development, the H1c gene and its promoter acquired epigenetic patterns typical of rod-specific genes. Our data suggest that histone H1c gene expression is developmentally up-regulated to promote facultative heterochromatin in mature rod photoreceptors.     

不同年龄小白鼠全脑细胞质氨酰tRNA合成酶活力的比较

从不同年龄(20天,30天,1年)的小白鼠全脑制得细胞质混合氨酰tRNA合成酶。用异源体系(即用酵母tRNA和小白鼠全脑氨酰tRNA合成酶)测定了氨酰tRNA合成酶分别载运~3H标记的Asp、Gly、Glu、Lys和Ala的活力。结果表明除未检出tRNA~(Glu)的合成酶活力外,对其余四种氨基酸都有明显的活力,特别是年龄20天小白鼠的氨酰tRNA合成酶对~3H-Gly具有高达35％的载运活力。对~3H-Gly、~3H-Lys和~3H-Ala的载运活力有随增龄而下降的趋势,但对~3H-Asp的载运活力则随年龄增长而增高。     

On the stability of DNA in photoreceptor cells of rat retina

Summary DNA turnover in post-mitotic photoreceptor cells of F344 rat retina was investigated. Developing retinas of newborn rats were labelled by multiple injections of (methyl-³H)thymidine. One eye was removed on day 60 and embedded in paraffin. The groups of rats were killed 180, 365, 540 or 730 days later and the second eye was removed. Autoradiographic studies on pairs of eyes showed no detectable DNA turnover in photoreceptor cells up to the end of the experiment (near median life-span, 50% survival age). The DNA of these photoreceptor cells is not replaced through the life span of the animals; the results thus suggest that it is very stable and possibly protected in a specific manner.