鲫鱼、牛蛙、鸡和大鼠视网膜锌离子分布的光镜观察

本文应用neo-Timm染色技术研究了鲫鱼、牛蛙、鸡和大鼠视网膜内锌离子的分布状况。结果发现上述动物视网膜内均存在锌离子。锌离子位于视网膜光感受器的内段、外网层、双极细胞、无长突细胞和神经节细胞等处。鲟鱼视网膜的部分光感受器胞体锌离子染色阳性。此外，牛蛙、鸡和大鼠等动物视网膜内同层锌离子亦呈弥漫性着色。提示在较高等动物作为神经调质的锌离子对视网膜神经无视觉信号的传导与调制可能具有更为广泛的意义。     

酪氨酸羟化酶样免疫反应神经元在幼年虎斑蝾螈视网膜的定位研究

本文应用免疫细胞化学方法对幼年虎斑蝾螈视网膜酪氨酸羟化酶(Tyrosine-Hydroxylase,TH)样免疫反应神经元进行了定位研究。90%免疫反应阳性细胞位于内核层最内排的无长突细胞,而10%的细胞位于节细胞层,暂称为异位无长突细胞。TH样免疫反应细胞的突起在内网层第一亚层分支最密,呈致密带,第3和5亚层相对地只有少量分布;在内核层不到1%的TH样免疫反应细胞,从胞体发出短突向外网层伸延,然而这些突起没有跨越过整个内核层,外网层也没有发现免疫阳性反应细胞的突起。视网膜平储片显示,TH样免疫反应无长突细胞和异位无长突细胞的分布遍及视网膜中央和周边部,TH祥免疫反应无长突细胞的密度每平方毫米为49±13个细胞(平均数±标准误)。绝大多数的细胞呈星形,发出3个或3个以上的初级突起,一些细胞在胞体相对两极发出突起,其突起一般分支很少,有时末端分支膨大呈念珠状。某些突起很长与相邻的TH样免疫反应无长突细胞的树突野之间有大量的重叠,而且常常看到在内网层多于一个平面上相互连接成网。     

脑啡肽与生长抑素在鸡视网膜无长突细胞共存的免疫组织化学研究

本文介绍用免疫组织化学的单标和双标技术研究脑啡肽(ENK)和生长抑素(SOM)在鸡视网膜无长突细胞的定位和共存。单标的实验结果表明,一些SOM免疫反应阳性无长突细胞的形态、胞体在内核层的位置及其突起在内网层的分支式样与某些ENK免疫反应阳性无长突细胞相似,虽然其突起在内网层的第3、4亚层形成的丛网不象ENK免疫反应阳性突起那样丛密,在内网层的第5亚层也未见SOM免疫阳性突起。双标的实验结果表明,一些无长突细胞显示ENK和SOM两种免疫阳性反应,而另一些无长突细胞分别只显示ENK或SOM阳性免疫反应。文中还对视网膜神经多肽间或与经典神经递质的共存进行了讨论。     

大鼠丘脑前核神经元内γ-氨基丁酸及其受体的表达

目的:探讨大鼠丘脑前核内γ-氨基丁酸(GABA)及其GABAA受体(GABAARα1和β2subunits)的表达,从形态学角度为系统研究丘脑前核的功能提供依据。方法:分别采用包埋后胶体金免疫电镜技术和原位杂交检测丘脑前核内GABA及GABAARα1和β2mRNA的表达。结果:(1)在丘脑前核,GABAARα1和GABAARβ2阳性神经元分布较密集,细胞形态较一致。空白对照切片为阴性,未见GABAARα1和GABAARβ2mRNA表达阳性神经元。(2)GABA胶体金免疫反应切片上,GABA胶体金颗粒浓重标记GrayⅡ型轴突终末,而树突、神经元、胶质细胞及背景标记极少。GABA能阳性轴突终末与中小型树突形成对称性轴-树突触,也与神经元胞体形成对称性轴-体突触。结论:提示在丘脑前核能够合成GABAARα1和GABAARβ2,且GABA能轴突终末与神经元的树突或胞体形成对称性突触。     

猫年龄相关的视网膜γ-氨基丁酸和神经丝蛋白表达

目的：对老年猫与青年猫视网膜的变化进行比较研究。方法：运用免疫组织化学ABC法显示卜氨基丁酸（GABA）、神经丝蛋白（NF）阳性结构。显微镜下观察GABA、NF阳性反应,并计阳性细胞数。结果：老年猫、青年猫GABA免疫反应阳性结构均见于无长突细胞、内网状层、神经节细胞和神经纤维层。老年猫NF阳性结构见于水平细胞、无长突细胞以及神经节细胞。青年猫无长突细胞未见阳性反应。与青年猫相比较,老年猫视网膜中GABA、NF阳性反应强于青年猫,免疫反应阳性细胞显著增加。结论：老年猫视网膜在衰老过程中呈现年龄相关的结构改变,这可能是造成视觉功能衰退的重要因素之一。     

锌转运体ZNT7在小鼠视网膜的定位分布

目的研究锌转运体-7(zinc transporter 7,ZNT7)在小鼠视网膜的定位和分布。方法应用免疫组织化学技术检测CD-1小鼠视网膜内的ZNT7免疫反应产物的表达。结果ZNT7在小鼠视网膜内分布广泛,在神经节细胞和色素上皮细胞内ZNT7免疫阳性反应产物的表达最丰富,在无长突细胞和视神经纤维层中ZNT7免疫阳性反应产物为中等程度的表达,在内网层、外网层和光感受器外节中ZNT7免疫阳性染色较淡,在外核层和光感受器内节中ZNT7几乎没有表达。结论ZNT7可能在维持视网膜锌稳态过程中起到重要的作用。     

大白鼠脊髓前角内含片氨基丁酸神经元的化学神经解剖学研究

用HRP与免疫细胞化学结合法和免疫电镜方法观察了大白鼠脊髓L_(4～5)节段内前角含γ-氨基丁酸(GABA)神经元的分布及其与躯体传出的关系。光镜下,在脊髓前角各层,包括位于前角的前外侧部的Rexed IX层,均有GABA免疫反应阳性神经元胞体和末梢分布。GABA阳性胞体为圆形或三角形,具有多个突起,可分大、中两型。电镜下,GABA样免疫反应产物呈细小颗粒状沉淀,分布于核周质、树突和轴突内。在轴突末梢,免疫反应产物定位于小透亮囊泡和线粒体外膜周围。GABA阳性树突接受GABA阳性或阴性轴突的传入性突触。HRP与免疫细胞化学结合法显示:在Rexed IX层存在HRP单标细胞、GABA单标细胞和HRP/GABA双标细胞。双标细胞占HRP标记细胞总数的79%。以上结果证明:在Rexed IX层的前角神经细胞内含有GABA,这些神经元参与躯体传出,并在突触水平接受来自GABA神经元的自身调节。     

大鼠三叉神经脊束核尾侧亚核内SP受体阳性神经元、FOS阳性神经元及初级传入C纤维和终末分布的研究

用免疫组织化学和组织化学方法对大鼠三叉神经脊束核尾侧亚核（Ｖｃ）内ＳＰ受体阳性神经元、ＦＯＳ阳性神经元及初级传入Ｃ纤维和终末的分布及相互之间的关系进行了观察。ＳＰ受体阳性神经元的胞体及树突主要分布在此核的Ⅰ、Ⅱ层，Ⅰ层多于Ⅱ层；１０％福尔马林刺激大鼠口周区后诱导的ＦＯＳ阳性神经元分布于此核的Ⅰ～Ⅳ层及其内侧的网状结构，但主要集中在Ⅰ、Ⅱ层，Ⅱ层多于Ⅰ层；ＢＳＩ－Ｂ４标记的初级传入Ｃ纤维及其终末也密集地分布于此核的Ⅰ、Ⅱ层，且Ⅱ层多于Ⅰ层。多重反应的结果显示：在Ｖｃ的Ⅱ层和Ⅰ层内，ＳＰ受体阳性神经元的胞体及树突和ＦＯＳ阳性神经元胞体的周围可见许多ＢＳＩ－Ｂ４标记的纤维及终末；部分ＳＰ受体阳性神经元也呈ＦＯＳ阳性，少数ＳＰ受体和ＦＯＳ的双重阳性神经元周围也有ＢＳＩ－Ｂ４标记的纤维和终末。以上结果说明：（１）传递面口部痛信号的Ｃ纤维主要终止在尾侧亚核的Ⅰ、Ⅱ层，与ＳＰ受体阳性神经元的分布区重叠，提示这些Ｃ纤维可能含ＳＰ；（２）参与西口部痛信息传递的ＦＯＳ阳性神经元主要分布于Ｖｃ的Ⅱ层，它们与初级传入Ｃ纤维终末的分布区重叠，其中的部分ＰＯＳ阳性神经元也呈ＳＰ受体阳性，从而进一步地证明了ＢＳＩ－Ｂ４标记的初级传入Ｃ纤?     

神经肽Y样免疫反应神经元在蟾蜍视网膜的定位与分布

用免疫组织化学ABC方法研究神经肽Y(NPY)样免疫反应神经元在蟾蜍视网膜的定位、形态与分布。结果表明:NPY样免疫反应仅存在于无长突细胞中。在102个免疫反应阳性无长突细胞中,92%为Ⅰ型,8%为Ⅱ型。NPY样免疫反应阳性纤维分布于内网层并密集呈三条带,分别位于第1亚层,第2、3亚层交界处和第4、5亚层之间。在视网膜平铺片上,NPY样免疫反应阳性胞体均匀分布于视网膜中央区和周围区,其密度为27±8个/mm~2(均数±标准差)。它们的树突野呈对称和非对称两型,前者的树突野大小为300—500μm×100—300μm,后者的长突约为200—400μm。     

自发性高血压大鼠视网膜内含一氧化氮合酶神经元的研究

本实验用ＮＡＤＰＨ－黄递酶组织化学染色法观察了自发性高血压大鼠和京都种大鼠（ＷＫＹ，正常对照）视网膜内一氧化氮合酶（ＮＯＳ）的变化。结果显示，ＮＯＳ阳性神经元位于内核层和视网膜节细胞层。ＳＨＲ组视网膜ＮＯＳ阳性细胞属无长突细胞和移位无长突细胞。偶见最怀的节细胞。ＮＯＳ阳性无长突细胞和节细胞胸质显强阳性反应，可较长而清晰的突起，ＮＯＳ阳性神经元的分布密度长，且在视网膜中央区（视神经盘附近）的分布密度     

大鼠,金黄地鼠和家兔视网膜内一氧化氮合酶分布的比较

用ＮＡＤＰＨ黄递酶组织化学染色法观察了正常成年大鼠、金黄地鼠和家兔视网膜内一氧化氮合酶的分布，并比较了３种不同动物的区别。结果显示，在视网膜内ＮＯＳ阳性神经元主要为分布于内核层的无长突细胞、节细胞层的移位无长突细胞和少数节细胞，不同种类动物的视网膜内，ＮＯＳ阳性细胞的配布、密度和细胞形态均有差异。大鼠视网膜内ＮＯＳ阳性细胞多尾于内核层无长突细胞和节细胞层移位无长细胞，偶见于视网膜节细胞。金黄地鼠视     

Neuronal and glial localization of homocysteate-like immunoreactivity in the rat retina

Summary To study the distribution ofl-homocysteate in the rat retina, specific polyclonal and monoclonal anti-homocysteate antibodies have been used in combination with a highly sensitive postembedding method for light microscopic immunocytochemistry. In central and peripheral retina, the most strongly immunoreactive cell bodies lay in the inner nuclear layer. They represented about 17% of the total neuronal cell population of the layer and were identified as bipolar cells (19–20% of cells in the outer half of the inner nuclear layer) and amacrine cells (15% of cells in the inner half of the inner nuclear layer). A third cell type showing heavy homocysteate-like immunoreactivity was identified as Müller glial cells. Characteristically, their descending processes formed three immunoreactive bands in the inner plexiform layer. Furthermore, the outer and inner limiting membranes as well as glia around and between ganglion cell axons and in the vicinity of blood vessels were labelled intensely. Photoreceptors and their terminals, and ganglion cells, were not immunostained. These findings indicate the presence of homocysteate in some bipolar and amacrine cells of the inner nuclear layer and support a role for this sulphur-containing excitatory amino acid as a neurotransmitter candidate in the retina.     

Electron microscopy of glutamate decarboxylase (GAD) immunoreactivity in the inner plexiform layer of the rhesus monkey retina

Summary With indirect immunofluorescence, glutamate decarboxylase (GAD), the GABA synthesizing enzyme, was localized to cell bodies in the inner half of the inner nuclear layer and a few in the outer tier of the ganglion cell layer in the rhesus monkey retina. In the inner plexiform layer there were three strongly GAD-immunoreactive laminae separated by two less immunoreactive laminae. Electron microscopy demonstrated that the GAD was contained in amacrine cells and these GAD-immunoreactive amacrines were primarily pre- and postsynaptic to biopolar cell axon terminals. The GAD-containing processes possessed small synaptic vesicles and formed synapses that could be characterized as symmetrical. Large, dense-cored vesicles were often found in the cell bodies and synaptic processes of the GAD-immunoreactive amacrine cells. As the vast majority of the synaptic input and output of the GAD-containing amacrine cells was to and from bipolar cells and the strongest GAD-immunoreactivity correlated with the endings of bipolar cells that connect with a single cone, the functional effects of GABA in the primate retina are likely to be found in the responses of single cone pathways in the inner plexiform layer.     

Glycinergic synaptic transmission to bullfrog retinal bipolar cells is input-specific

Glycinergic inhibitory postsynaptic currents (IPSCs) focally elicited at the dendrites and axon terminals were recorded from bipolar cells in the bullfrog retinal slice, using the whole-cell clamp technique. IPSCs driven by input from interplexiform cells at bipolar cell dendrites (ipc-IPSCs) had a much slower decay time constant (25.2 +/- 7.8 ms) than IPSCs driven by input from amacrine cells at bipolar cell axon terminals (ac-IPSCs) (14.7 +/- 5.5 ms). Furthermore, peak-scaled non-stationary noise analysis revealed that the weighted mean single-channel conductance of the glycine receptors underlying bipolar cell dendritic ipc-IPSCs (20.8 +/- 6.6 pS) was significantly larger than that of those underlying bipolar cell axon terminal ac-IPSCs (12.9 +/- 2.9 pS). These results demonstrate that glycinergic synaptic transmission with different properties at bipolar cell dendrites and axon terminals differentially mediates intraretinal centrofugal signal transfer from the inner retina to the outer retina provided by interplexiform cells and lateral inhibition offered by amacrine cells in the inner retina.     

Morphology and retinal distribution of tyrosine hydroxylase-like immunoreactive amacrine cells in the retina of developingXenopus laevis

Summary The development of neurons immunoreactive to tyrosine hydroxylase (TH-IR) in the retina ofXenopus laevis was investigated from stage 53 tadpoles to adult, by using an antibody against tyrosine hydroxylase. At all developmental stages, most of the immunoreactive somata were located in the inner nuclear layer, and a few in the ganglion cell layer. Immunoreactive processes arborised in the scleral and vitreal sublaminae of the inner plexiform layer, indicating that these cells were bistratified amacrine cells. However, occasionally a few immunoreactive processes were observed projecting to the outer plexiform layer, suggesting the presence of THIR interplexiform cells. The number of immunoreactive amacrine cells in the inner nuclear layer per retina increased from 204 at stage 53 tadpole to 735 in adult, while the number of immunoreactive amacrine cells in the ganglion cell layer did not change significantly over the same period. Retinal area increased from 1.95 mm² at stage 53 to 23.40 mm² in the adult, and correspondingly cell density in the inner nuclear layer decreased from 104/mm² to 31/mm². At all stages there was an increasing density towards the ciliary margin, but this gradient decreased with age. The soma size of immunoreactive amacrine cells increased with age, and was consistently larger in the central than in the peripheral retina. Dendritic field size was estimated to increase 13-fold, from stage 53 to adult. This study shows that tyrosine hydroxylase-like immunoreactive amacrine cells are generated continuously throughout life, that after metamorphosis the retina grows more by stretching than by cell generation at the ciliary margin, and that the increase of dendritic field size is proportional to the increase in retinal surface area.On leave from Department of Anatomy, Zhanjiang Medical College, Guangdong, People's Republic of China     

Discrete distribution of cholinergic and vasoactive intestinal polypeptidergic amacrine cells in the rat retina

The distribution and fine structure of cholinergic amacrine cells of the rat retina were observed using monoclonal anti-choline acetyltransferase (ChAT) antibody. The ChAT-immunoreactive cholinergic cells were located in the innermost zone of the inner nuclear layer and in the outer zone of the ganglion cell layer, and they formed two distinct bands in the inner plexiform layer. The ChAT-immunoreactive materials were diffusely localized throughout the cytoplasm except for the nucleus, mitochondria, Golgi apparatus and the interior of the endoplasmic reticulum and vesicular components. The sequential immunostaining of one and the same section with both the ChAT antibody and the antiserum against vasoactive intestinal polypeptide (VIP) revealed clearly that the cholinergic amacrine cells are distinct from the VIP-immunoreactive amacrine cells.     

The light microscopic localization of substance P- and somatostatin-like immunoreactive cells in the larval tiger salamander retina

Summary Light microscopic immunocytochemistry was utilized to localize the populations of substance P (SP)- and somatostatin (SOM)-like immunoreactive cells in the larval tiger salamander retina. Of 104 SP-immunostained cells observed, 82% were Type 1 amacrine cells. Another 8% of the SP-cells were classified as Type 2 amacrine cells, while 10% of the SP-cells had their cell bodies located in the ganglion cell layer and were designated as displaced amacrine cells. Each type of SP-like immunoreactive cell was observed in the central and peripheral retina. SP-immunopositive processes were observed in the inner plexiform layer as a sparse plexus in sublamina 1 and as a denser network of fibers in sublamina 5. Seventy-eight percent of the 110 somatostatin-immunopositive cells observed were designated as Type 1 amacrine cells. Another 12% of SOM-cells were classified as displaced amacrine cells, while only two SOM-immunopositive Type 2 amacrine cells were observed. Nine percent of the SOM-cells were designated as interplexiform cells, based on their giving rise to processes distributing in the outer plexiform layer as well as processes ramifying in the inner plexiform layer. Each type of SOM-immunoreactive cell was observed in the central and peripheral retina, with the exception of the Type 2 amacrine cells, whose somas were only found in the central retina. Lastly, SOM-immunopositive processes in the inner plexiform layer appeared as a fine plexus in sublamina 1 and as a somewhat denser network of fibers in sublamina 5.     

Distribution of GABA immunoreactivity in kainic acid-treated rabbit retina

Ischaemic retinal cell degeneration seems to involve both NMDA and non-NMDA receptor over stimulation. However, different retinal cell types differ largely in their susceptibility to excitatory amino acid induced neurotoxicity. We have investigated the vulnerability of GABAergic cells in the rabbit retina to the non-NMDA receptor agonist kainic acid (KA). The distribution of GABA immunoreactivity (GABA-IR) was examined in the central inferior retina at different survival times (5 h–6 days) following an intra-ocular injection of 140 nmol KA and compared to that of control and untreated retinas. In the normal retina, the majority of GABA-positive cells (79%) were located in the inner nuclear layer (INL), in one to four cell rows next to the inner plexiform layer (IPL), and in one cell row next to the outer plexiform layer (OPL). The remainder (21%) were found in the ganglion cell layer (GCL). Dense immunoreactivity was seen throughout the IPL. In the OPL, stained dots and occasional immunoreactive large processes could be seen. KA-exposed retinas processed for GABA immunocytochemistry 5 and 24 h after the injection showed an 85% reduction in the number of GABA immunoreactive cells. About the same degree of depletion was seen among GABA-IR cells located at different retinal levels. However, at these survival times, immunostaining was observed in three distinct bands in the IPL, indicating that the vulnerability to KA is not uniformly distributed among all GABAergic cells. At 48 h, an additional decrease in the number of labelled cells was noted, but immunoreactive cells were still found both in the INL and GCL. Even 6 days after KA treatment, a few stained cell bodies were seen in the INL next to the IPL, as well as a few processes in the IPL. The study shows that KA receptor overstimulation induces a marked depletion of the endogenous cellular GABA pools of the central rabbit retina, most likely as a result of GABAergic cell loss. However, a small population of GABAergic cells located in the INL appears to be less vulnerable to the toxic effects of 140 nmol KA.     

Demonstration of a substance P-like immunoreactivity in retinal cells of the rat

The distribution of substance P (SP)-like immunoreactivity in the rat retina was investigated by immunohistochemistry. SP-positive cells were found throughout the retina. The majority of them were located in the proximal portion of the inner nuclear layer and the processes from these cells directed to the inner plexiform layer where they ramified, suggesting that SP-positive cells located in this region probably are amacrine cells. Few SP-positive cells were seen within the ganglion cell layer. They were considered displaced amacrine cells.