单眼剥夺大鼠视皮层及外侧膝状体中生长相关蛋白(GAP-43)的表达及其意义

目的研究生长相关蛋白(GAP-43)在正常大鼠与视觉剥夺性大鼠视皮层及外侧膝状体中的表达情况。方法缝合2周龄大鼠单侧眼睑30天,切取外侧膝状体和视皮质,应用免疫细胞化学SP法技术染色和计算机图像分析GAP-43在正常组和单眼视觉剥夺组大鼠外侧膝状体和视皮层的表达及变化。结果 1．GAP-43在正常大鼠视觉系统的表达主要见于外侧膝状体全层和视皮质Ⅱ-Ⅳ层神经元胞膜中,呈环状或点状棕黄色免疫阳性反应;2．在敏感期内视觉剥夺眼对侧外侧膝状体和视皮质GAP-43表达的免疫阳性神经元染色变淡(P<0．05), 且免疫阳性神经元数目减少(P<0．05)。结论单眼视觉剥夺大鼠外侧膝状体和视皮质GAP-43表达均降低,提示 GAP-43在视觉系统的作用可能是弱视发生的分子生物学基础之一。单眼剥夺性大鼠视觉系统的GAP-43表达降低可能是由于剥夺眼视觉系统神经元在发育敏感期内,长期视觉剥夺效应使其在双眼竞争突触位点时处于劣势, 表达GAP-43的能力降低。     

P物质在单眼剥夺性弱视猫外侧膝状体中的表达

目的检测SP在单眼剥夺弱视猫LGN中的表达,并探讨其在弱视发病中的意义.方法采用免疫组化APA法,对7例正常猫和8例单眼剥夺弱视猫LGNSP免疫阳性神经元及神经纤维进行定位并定量研究其变化.结果在单眼剥夺猫剥夺侧LGN的A1层SP表达显著下降(P＜0.05).结论单眼剥夺可造成剥夺侧LGN剥夺眼相应输入层次的SP表达下降,从而促进弱视的发生发展.     

Changes in visual fields and lateral geniculate nucleus in monkey laser-induced high intraocular pressure model

Monkey eyes are useful for ophthalmologic research into eye diseases because their histological and functional properties are very similar to those of humans. The monkey laser-induced high intraocular pressure (IOP) model is a common model for ophthalmologic research, especially into glaucoma. Although several studies using this model have focused on changes in visual field, retinal ganglion cells (RGC), and lateral geniculate nucleus (LGN), clear relationships among these changes in one and the same monkey have not been established. We therefore examined visual field changes, RGC and LGN numbers, and glial fibrous acidic protein (GFAP) immunohistochemistry in the LGN in each of two monkeys. Visual field sensitivity, RGC number, and neuronal density of LGN were all decreased by high IOP. The relationship between loss of RGC and decrease in visual field sensitivity depended on the eccentricity from the fovea. Moreover, LGN immunohistochemistry revealed greater increases in GFAP expression in the layers receiving a neuronal input from the high IOP eye than in those receiving a neuronal input from the contralateral untreated eye. From these results, we suggest that glaucoma may lead to changes in glial function not only in the retina, but also in the visual pathway, and that such central nervous system changes may be a hallmark of neuropathy in glaucoma, as in other neurodegenerative diseases.     

Magnetic resonance imaging assessment of the lateral geniculate nucleus volume and height in patients with glaucoma: a Meta-analysis

AIM: To evaluate the lateral geniculate nucleus (LGN) volume and height using magnetic resonance imaging (MRI) in glaucoma patients. METHODS: Literatures retrieval was carried out through PubMed, Web of Science, Embase, and Cochrane Library. Studies that compared the volume and height of LGN in glaucoma patients with that in control subjects were included. The volume and height of LGN were extracted from the included studies. The Review Manager 5.4.1 software was used for the Meta-analysis. RESULTS: This Meta-analysis included 10 cross-sectional studies, including the eyes of 223 glaucoma patients and 185 healthy controls. Compared with the control subjects, the volume and height of LGN in glaucoma patients measured by MRI were significantly reduced {-29.13 mm3, 95% [confidence interval (CI): -44.82 to -13.43, P=0.0003; -0.61 mm, 95%CI: -0.78 to -0.44, P<0.00001, respectively]}. Subgroup analysis demonstrated that the differences of LGN volume and height between glaucoma patients and control subjects in the older group were smaller than that in the younger group, and LGN volume decreased with the increase of glaucoma severity. CONCLUSION: The results demonstrate that the volume and height of LGN are decreased in glaucoma patients, and LGN volume can be considered a parameter of glaucoma severity.     

c-Fos immunoreactivity in the neurons of the lateral geniculate nucleus in albino rats by light exposure after dark rearing

Purpose

To investigate the effect of dark rearing immediately after birth on the maturation of the visual relay neurons in the lateral geniculate nucleus.

Methods

Fifty neonatal rats were used. Neonates of the control groups were raised under a normal light/dark cycle. Neonates of the experiment groups were dark reared and isolated from light during the entire experimental period, then exposed to the sun light for 1 hour before sacrifice.

Results

In the control groups, the neurons in the dorsal lateral geniculate nucleus developed normally at each age tested. In the experiment groups, the cytoplasm of the large neurons in the dorsal lateral geniculate nucleus of 2-week-old rats contained small vesicles, and the cytoplasm of the large neurons of 4-week-old rats was converted into a vacuole-like space. Moreover, c-Fos immunoreactivity of the large neurons in the dorsal lateral geniculate nucleus in the experiment groups was significantly increased compared to that of the control groups.

Conclusions

We suppose that the maturation of the neurons in the lateral geniculate nucleus might be influenced by light stimulation during the critical period. Furthermore, c-Fos could be a marker of the functional activity of the visual relay neurons of the lateral geniculate nucleus in albino rats.     

Segregation of short-wavelength sensitive ("blue") cone signals among neurons in the lateral geniculate nucleus and striate cortex of marmosets

We measured functional input from short-wavelength selective (S) cones to neurons in the dorsal lateral geniculate nucleus (LGN) and striate cortex (area V1) in anaesthetized marmosets. We found that most magnocellular (MC) and parvocellular (PC) cells receive very little (<5%) functional input from S cones, whereas blue-on cells of the koniocellular (KC) pathway receive dominant input from S cones. Cells dominated by S cone input were not encountered in V1, but V1 cells received more S cone input than PC or MC cells. This suggests that S cone inputs are distributed broadly among neurons in V1. No differences in strength of S cone inputs were seen on comparing dichromatic and trichromatic marmosets, suggesting that the addition of a medium-long wavelength selective cone-opponent (“red-green”) channel to a dichromatic visual system does not detectably affect the chromatic properties of the S cone pathways.     

关键期内反缝合治疗前后单眼形觉剥夺性弱视大鼠模型外侧膝状体PSD-95的表达

目的探讨关键期内单眼形觉剥夺弱视大鼠模型反缝合治疗前后外侧膝状体突触后致密蛋白-95（PSD-95）的表达规律。方法14日龄大鼠随机为剥夺组、正常组及反缝合治疗组,经造模成功后取材,采用免疫组化和RT-PCR技术检测并分析各组大鼠外侧膝状体PSD-95蛋白和PSD-95mRNA表达水平的变化。结果同年龄段弱视组外侧膝状体PSD-95呈阳性神经元密度降低,PSD-95mRNA的表达减少（P<0.01）;同年龄段反缝合治疗组外侧膝状体较弱视组PSD-95呈阳性神经元密度增加,PSD-95mRNA的表达增多（P<0.05）,但仍低于正常组（P<0.05）。结论单眼剥夺及反缝合治疗影响大鼠外侧膝状体PSD-95的表达,提示PSD-95参与了视觉发育外侧膝状体可塑性的变化过程,是弱视发病的重要分子机制之一;验证了关键期内反缝合治疗对弱视外侧膝状体神经元功能状态的恢复作用,为临床弱视遮盖治疗提供了理论依据。     

Organization of geniculate inputs to visual cortical cells in the cat

Neuronal connectivity between a geniculate cell and a striate cortical cell was examined by cross-correlograms between their impulse activities. Delayed positive correlations were found in 82 pairs, and the onset delay of the positivity was short enough in 65 pairs to infer that the geniculate cell monosynaptically excited the cortical cell. These monosynaptic excitations were found in both simple and complex cells. By determining connectivity of a cortical cell with multiple geniculate cells, the convergence of X and Y geniculate cells and that of on-center and off-center geniculate cells was demonstrated in several striate cells.     

Chronic ocular hypertension induces dendrite pathology in the lateral geniculate nucleus of the brain

In glaucoma, there is atrophy and loss of retinal ganglion cells (RGC), in addition to atrophy and loss of target neurons in the lateral geniculate nucleus (LGN) of the brain. To investigate possible changes to the dendrites of LGN neurons in glaucoma, a selective marker for dendrites called microtubule-associated protein-2 (MAP2) was used. The LGNs from five monkeys with varying degrees of optic nerve fiber loss were compared to those from five normal control monkeys. Dendrites in magno- and parvocellular layers connected to the glaucomatous eye were evaluated. In controls, long MAP2-positive dendrites with multiple fine branches were seen. However, chronic ocular hypertension induced striking disruption of dendrites with a thickened and shortened appearance. Dendrite field area was significantly reduced in the glaucoma group compared to controls. Sholl analysis revealed reduced dendrite complexity by 47% and 41% in magnocellular layer 1 and parvocellular layer 6, respectively in the glaucoma group compared to controls. The striking dendrite changes in the LGN following chronically elevated intraocular pressure may be relevant to early visual dysfunction in glaucoma.     

Oxidative injury by peroxynitrite in neural and vascular tissue of the lateral geniculate nucleus in experimental glaucoma

In glaucoma, recent studies show that neural degeneration extends beyond the retinal ganglion cells to include target neurons in the lateral geniculate nucleus of the brain. The pathobiology of LGN degeneration in glaucoma is as yet unknown. We investigated whether peroxynitrite-mediated oxidative stress plays a role in glaucomatous degeneration of the LGN. Nitrotyrosine (NT), a marker for peroxynitrite-mediated oxidative injury, was studied in right LGN sections from monkeys with experimental unilateral glaucoma in the right eye and from normal controls. Immunoreactivity for NT was analyzed using bright-field microscopy. The density of NT profiles localized in neural tissue was determined for LGN layers (2,3,5) connected to the glaucoma eye and LGN layers (1,4,6) connected to the non-glaucoma eye. Density was calculated for each LGN layer by dividing the number of NT profiles by the cross-sectional area of each LGN layer. Blood vessels in each LGN were examined for NT formation. NT formation was detected in LGN layers of all monkeys with glaucoma. Quantitative analysis revealed that compared to controls, the density of NT profiles was increased in monkeys with glaucoma in LGN layers connected to glaucoma and non-glaucoma eyes. The mean density of NT profiles (+/-SEM) in neural tissue was significantly increased in glaucoma LGN layers compared to those of controls (2.30+/-0.56 vs. 0.29+/-0.12; P=0.016). Nitrotyrosine was readily apparent in LGN blood vessel endothelium in glaucoma, and not detected in blood vessels of control LGNs. The presence of NT in neural and vascular tissue of the glaucomatous LGN implicates peroxynitrite-mediated oxidative cell injury in the pathobiology of central neural degeneration in glaucoma.     

Ascending, descending and local control of neuronal activity in the rat lateral geniculate nucleus

Mechanisms of control for activities of relay neurons (P-cells) in the rat dorsal lateral geniculate nucleus (LGNd) are surveyed with special reference to ascending projection arising from the locus coeruleus (LC), the local projection from the visual portion of the thalamic reticular nucleus (vTRN) and the descending projection from the visual cortex (VC). Noradrenaline released from terminals of LC neurons exerts a facilitatory influence on P-cell activity via alpha-receptors. A recurrent projection of vTRN neurons on P-cells is inhibitory, utilizing GABA as a transmitter. P-cells receive an excitatory input from corticothalamic neurons of VC. However, in many P-cells the corticofugal excitation is counterbalanced by inhibition arising in vTRN neurons which are invariably exited by the collateral branches of the corticogeniculate axons. Thus, LGNd is not a simple relay station, but various modifications of visual information are made in this nucleus.     

Glaucoma alters the expression of NGF and NGF receptors in visual cortex and geniculate nucleus of rats: effect of eye NGF application

We investigated the effect of glaucoma (GL) on nerve growth factor (NGF) presence in two brain visual areas. Rats with elevated intraocular pressure (EIOP), induced by hypertonic saline injection in the episcleral vein, were treated with eye topical application of saline or NGF. Rats were subsequently sacrificed, and brain tissues were used for immunohistochemical, biochemical, and molecular analyses. We found that GL alters the basal level of NGF and NGF receptors in brain visual centers and that NGF eye application normalized these deficits. These findings demonstrate that the reduced presence of NGF can arise due to degenerative events in retinal and brain visual areas.     

Antibody labeling of functional subdivisions in visual cortex: Cat-301 immunoreactivity in striate and extrastriate cortex of the macaque monkey.

We have examined the distribution of immunoreactivity for the monoclonal antibody Cat-301 in visual cortex of the macaque monkey. Remarkably, those portions of striate cortex (V1) and extrastriate cortex that are most immunoreactive for Cat-301 are anatomically interconnected and are dominated by inputs arising from the magnocellular layers of the LGN (which are themselves highly immunoreactive). In particular, we found that a band of Cat-301 labeled neurons known to exist in layer 4 of V1 is centered on the boundary between layers 4C alpha and 4B and thus includes portions of both the primary target of the magnocellular LGN and its subsequent relay through layer 4B. We also demonstrated consistently strong Cat-301 immunoreactivity in all three extrastriate targets of layer 4B: areas V3, MT, and the cytochrome-oxidase (CO) enriched thick stripes of V2. In V2, there was a close correlation between Cat-301 labeling and clusters of cells projecting to MT but not to V4. This was true even in regions where the CO pattern was equivocal or irregular, indicating that Cat-301 is a more reliable marker than CO for the thick-stripe subregions of V2. Finally, we found strong Cat-301 immunoreactivity in at least parts of areas V3A, the MST complex, and the posterior parietal complex, but not in area V4 or inferotemporal cortex. The molecular specificity revealed by this single marker thus correlates with functionally specific subdivisions at each hierarchical level over nearly the entire known extent of the visual pathway in macaques. This supports the notion that these subdivisions form an anatomically, physiologically, and now molecularly distinct pathway known as the M-stream.     

Biochemical and anatomical subdivision of the dorsal lateral geniculate nucleus in normal mice and in mice lacking the beta2 subunit of the nicotinic acetylcholine receptor

The cytoarchitectonically-uniform dorsal lateral geniculate nucleus (dLGN) can be biochemically and anatomically subdivided in wild-type mice: The nucleus' dorsolateral 'shell' region contains the majority of cells positive for the calcium-binding protein calbindin-D28k, and receives the strongest concentration of inputs from the superior colliculus. This subdivision remains normal in mice lacking the beta2 subunit of the nicotinic acetylcholine receptor. Although in these animals the dLGN contains fewer calbindin-positive cells, those cells are predominantly situated in the dorsolateral portion of the nucleus, and this region remains preferentially targeted by the colliculogeniculate projection.     

斜视性弱视猫发育过程中视皮层神经元NMDA-R1表达的免疫组织化学电镜观察

目的　研究不同发育阶段斜视猫视皮层神经元N 甲基 D 天门冬氨酸受体亚基 1(N methyl D aspartatereceptorsubunit 1,NMDA R1)在超微结构水平的表达与变化。方法　幼猫 11只 ,其中 6只猫在 2周龄行 1只眼外直肌断腱术产生单眼内斜。依动物处死时的年龄分为 3组 :3周龄组(斜视手术后 1周 ) ,2只正常和 2只斜视幼猫 ;5周龄组 (斜视手术后 3周 ) ,2只正常和 2只斜视幼猫 ;成年组 (6月龄 ) ,1只正常和 2只斜视性弱视猫。 3组动物均取初级视皮层组织进行冰冻切片 ,NMDA R1单克隆抗体标记后 ,分Ⅱ～Ⅲ层、Ⅳ层及Ⅴ～Ⅵ层各为一个区块行常规电镜染色切片 ,透射电镜观察。结果　 (1)电镜下分析 32 8个视皮层神经元 ,发现 3组正常猫的视皮层神经元NMDA R1标记阳性细胞数均高于斜视猫 (χ2 =4 2 8,4 4 1,4 89;P <0 0 5 )。 (2 )共计数 132 0个NMDA R1阳性突触 ,显示正常猫发育过程中 ,视皮层Ⅱ、Ⅲ层神经元细胞膜上的NMDA R1受体突触数多于Ⅳ～Ⅵ层 ,且随年龄增长而增加 (F =3 2 8,P <0 0 5 ) ;斜视猫视皮层神经元细胞膜上的NMDA R1受体突触数 ,3周龄组与正常幼猫组差异无显著意义 (F =0 17,P >0 0 5 ) ,5周龄组和成年组均较正常猫组显著减少 (F =2 6 94 ,4 7 0 1;P <0 0 0 1)。结论　 (1)正常猫发育过程     

慢性高眼压大鼠外侧膝状体神经元的损伤

目的观察在持续高眼压状态下大鼠外侧膝状体（lateral geniculate nucleus．LGN）细胞结构的变化及其与视神经纤维丢失的关系。方法通过烧灼大鼠巩膜表层静脉诱导建立大鼠慢性高眼压模型，左眼为实验眼，右眼为对照眼，分别于2、4、6个月后经心脏灌注内固定取材，对两侧LGN及视神经进行形态学观察；通过突触素P38单克隆抗体免疫组化技术，利用计算机图像分析，对LGN视神经末梢突触分布情况进行检测。并对两侧LGN及视神经的观察结果进行比较。结果随高眼压持续时间的延长。大鼠左眼视神经轴突数目以及右侧LGN神经元大小、密度显著减小；LGN内突触素P38免疫反应阳性产物平均光密度值呈下降趋势；LGN神经元的损伤与视神经轴突数目及突触素光密度值显著相关。结论持续性眼压升高对大鼠LGN有明显损伤作用；高眼压大鼠LGN的损伤继发于视神经的损伤。     

表没食子儿茶素没食子酸酯对大鼠视神经钳夹伤后外侧膝状体神经元保护作用的研究

背景研究证实绿茶提取物表没食子儿茶素没食子酸酯（EGCG）全身应用可到达视神经及视网膜组织,对视网膜缺血一再灌注和视神经钳夹伤后视网膜神经节细胞（RGCs）具有保护作用,但EGCG对视神经损伤后RGCs上位神经元的影响目前尚未见报道。目的探讨EGCG对大鼠视神经钳夹伤后外侧膝状体（LGN）神经元的保护作用。方法48只Wistar大鼠按随机数字表法分为正常对照组、假手术＋EGCG组、视神经钳夹＋生理盐水组、视神经钳夹＋EGCG组,每组12只。用40g微型视神经夹于大鼠右眼球后约2mm处夹持视神经60S建立视神经钳夹伤模型,假手术＋EGCG组、视神经钳夹＋EGCG组大鼠于造模前2d始每日腹腔内注射EGCG（25mg／kg）共5d,后改为口服（2mg／kg）,视神经钳夹＋生理盐水组大鼠以同样的方法注射生理盐水。于造模4周后处死大鼠并取脑组织,用Nissl染色法计数外侧膝状体背侧核（dLGN）神经元数目,用免疫组织化学染色法和Westernblot法观察神经丝蛋白（NF-L）在LGN的表达,比较各组大鼠dLGN中神经型一氧化氮合酶（nNOS）免疫组织化学染色阳性细胞数量。结果视神经钳夹伤后4周,假手术＋EGCG组左侧、右侧dLGN神经元数量与正常对照组相比差异无统计学意义（P=0．906、P=0．561）;视神经钳夹＋生理盐水组、视神经钳夹＋EGCG组钳夹同侧dLGN神经元数量与正常对照组相比,差异无统计学意义（P=0．794、P=0．646）,对侧dLGN神经元数量均低于正常对照组（P=0．000、P=0．015）,而视神经钳夹＋EGCG组钳夹对侧dLGN神经元数量高于视神经钳夹＋生理盐水组（P=0．007）;NF－L检测可见视神经钳夹＋EGCG组钳夹对侧LGN的NF－L表达量高于视神经钳夹＋生理盐水组（P=0．002）;dLGN的nNOS阳性细胞计数在正常对照组、假手术＋EGCG组、视神经钳夹＋EGCG组之间差异无统计学意义（P〉0．05）,而视神经钳夹＋生理盐水组钳夹对侧dLGN的nNOS阳性细胞高于视神经钳夹＋EGCG组（P=0．000）。结论EGCG对大鼠视神经钳夹伤后LGN的神经元可能具有一定的保护作用,这种保护作用可能与EGCG抑制了nNOS的表达有关。     

糖尿病大鼠脑外侧膝状体神经元退行性变及APP17肽的作用

目的 通过观察糖尿病大鼠外侧膝状体神经元超微结构改变和神经元内凋亡相关因子Bax、Bcl-2、Cyto C的表达，证实糖尿病大鼠是否存在脑内视觉传导通路外侧膝状体神经元退行性改变，APP17肽对其是否有改善作用。方法 用链脲佐菌素(STZ)腹腔注射诱发糖尿病模型，10周后取脑组织行Bax、Bcl-2、Cyto C的免疫组化染色，同时取外侧膝状体处脑组织作电镜观察。结果 糖尿病组外侧膝状体腹侧核内Bax、Cyto C阳性反应神经元数目多、染色深，Bcl-2三组间无明显差异，APP17肽治疗组的Bax、Bcl-2、Cyto C的表达接近正常组。超微结构发现糖尿病组神经元有固缩、核膜凹陷、线粒体肿胀等退行性变，给予APP17肽后上述改变明显好转。结论 糖尿病大鼠发生了外侧膝状体神经元的退行性改变，神经元可能处于凋亡前状态；APP17肽可改善糖尿病大鼠外侧膝状体神经元的退行性改变。     

Patterns of X and Y optic nerve fibre terminations in the dorsal lateral geniculate nucleus of the cat

The distributions of X and Y optic nerve fibre terminals in the A and A₁ laminae of the dorsal lateral geniculate nucleus (LGNd) of the cat have been determined by a method that eliminates the Y fibres. A pressure-blocking technique was used in a sterile operation to produce anterograde degeneration in the Y fibres with minimal effect on the X fibres. Subsequently the Fink/Heimer technique was used to stain for degenerating fibres. This showed a strong peak of degeneration in the ventral regions of the laminae. Tritiated leucine was injected into one eye either of a normal cat or of one in which the optic nerve had been pressure-blocked at least one week previously. Subsequent examination of the LGNd by autoradiography showed a more uniform distribution of label in the laminae deprived of Y input (i.e. the pattern of distribution of X fibres). Subtraction of this distribution from that produced in a normal cat (i.e. X + Y input) gave the Y distribution. As in the degeneration studies, this revealed a peak of label in the most ventral part of each lamina but also showed a smaller peak in the most dorsal regions.