胶质细胞活化相关炎症在青光眼视神经病变中的研究进展 △

青光眼是一种以视网膜神经节细胞(RGCs)及其轴突凋亡为特征的视神经退行性病变。越来越多的研究表明炎症和免疫反应在青光眼视神经病变中具有重要作用。在高眼压动物实验中,抑制早期胶质细胞活化及减少炎症因子释放,对RGCs和视神经具有保护作用。本文重点就星形胶质细胞和小胶质细胞活化及其产生的炎症因子,特别是视网膜及视盘部胶质细胞释放的炎症因子在青光眼视神经病变过程中的作用及相关机制进行综述,希望能给青光眼的研究和治疗带来新的启发。     

视神经胶质细胞的研究进展

视神经胶质细胞包括星形和少突胶质细胞两大类型 ,起源、分化谱系不同 ,性质、功能各异。 0 2A谱系是研究细胞分化、肿瘤发生过程中基因调控的理想的体外模型。未成熟胶质细胞能促进成年鼠损伤后视神经的再生和髓鞘的形成。综述了视神经胶质细胞的研究进展 ,为临床治疗中枢神经损伤、多发性硬化等疾病提供参考。     

视网膜神经胶质细胞与青光眼

青光眼视神经病变以进行性的视网膜神经节细胞丧失和相应的视功能损害为特征.导致青光眼视神经病变的病理生理机制尚不明确.在中枢神经系统,神经胶质细胞参与了神经元在受到机械、缺血、缺氧等损伤后的病理变化过程.胶质细胞参与青光眼视神经病变的机制复杂多样,但部分机制与中枢神经系统相似.本文就视网膜神经胶质细胞的生理功能、动物青光眼模型建立后胶质细胞的反应以及针对胶质细胞的青光眼视神经保护治疗手段做一综述.     

视神经夹持损伤模型大鼠视网膜和视神经小胶质细胞的活化

背景 外伤性视神经病变(TON)是继发于外力创伤下的急性视神经损伤,预后较差.小胶质细胞作为中枢神经系统中重要的免疫细胞,参与了中枢神经系统疾病与多种眼科疾病的病理生理过程.然而,小胶质细胞在TON的病理发展及损伤修复过程中的作用尚不明确. 目的 比较大鼠视神经夹持损伤后视神经与视网膜中小胶质细胞的形态变化、激活数量、分布情况及活化水平的差异. 方法 将35只SPF级健康雌性成年Sprague-Dawley(SD)大鼠按照随机数字表法分为正常对照组,造模后6h、3d、7d、14 d、30 d组和假手术组,每组5只大鼠.造模后各时间点组用夹持钳以50 g的夹持力在大鼠眼球后约2 mm处钳夹视神经10s,建立大鼠视神经夹持模型,假手术组大鼠行相同的手术操作但不夹持视神经,正常对照组不做任何处理.分别于上述时间点制备大鼠视神经和视网膜冰冻切片,采用lectin-FITC荧光标记抗体检测各组大鼠视神经和视网膜中的小胶质细胞数量和激活的小胶质细胞数量. 结果 正常对照组和假手术组大鼠视网膜中小胶质细胞主要位于内丛状层(IPL),少部分位于内核层(INL)和神经节细胞层(GCL),外核层(ONL)和外丛状层(OPL)未见小胶质细胞分布.正常对照组大鼠视网膜小胶质细胞的细胞体较小,以分支状为主,突触细长,可见二级分支.各模型组大鼠视网膜中小胶质细胞主要位于GCL和IPL,小胶质细胞在GCL的数量明显多于假手术组,小胶质细胞多为阿米巴状,部分呈半激活态,少见分支静息态.正常对照组、假手术组及造模后6h、3d、7d、14 d和30 d组大鼠视网膜中小胶质细胞数分别为6.40-±-1.52、7.20±2.05、12.00±3.54、14.00±4.06、18.00±4.36、18.40±3.13和10.80±1.92,造模后各时间点大鼠视网膜中小胶质细胞数量均明显多于正常对照组,造模后30 d小胶质细胞数量明显少于造模后7d和14d组,差异均有统计学意义(均P＜0.05);造模后3、7和14d组大鼠视网膜中激活小胶质细胞数量明显多于假手术组,差异均有统计学意义(P=0.024、0.009、0.023).正常对照组和假手术组大鼠视神经中小胶质细胞较小,呈棒状或分枝状,分布均匀且稀疏.造模后各时间点组小胶质细胞较假手术组细胞体积增大,呈阿米巴状并分布在近视神经夹持部位.造模后6h、3d、7d、14d大鼠视神经中小胶质细胞数量明显多于正常对照组,差异均有统计学意义(P=0.007、0.001、0.003、0.014).造模后30 d大鼠视神经中小胶质细胞数量明显少于造模后3d、7d和14 d组,差异均有统计学意义(均P＜0.05).造模后6h、3d和7d组大鼠视神经中活化小胶质细胞数量明显多于假手术组,差异有统计学意义(P=0.005、0.004、0.030),造模后14d、30 d大鼠视神经中活化的小胶质细胞数量较造模后3d组明显减少,差异均有统计学意义(P=0.021、0.004),造模后6h组视神经中激活态小胶质细胞增加并持续到造模后14d.结论 大鼠视神经夹持损伤后一定时间内视网膜及视神经中小胶质细胞增加并活化,视神经中小胶质细胞的活化及其衰减均早于视网膜,视神经中小胶质细胞活化程度更明显.     

转基因荧光小鼠视神经轴索钝性损伤后退行性病变观察

目的 建立单侧眼视神经轴索钝性损伤模型,观察视神经轴突退行性病变过程和小胶质细胞的变化.方法 将标记神经轴突的YFP小鼠和标记小胶质细胞的GFP小鼠分为手术组和正常对照组,并于视神经轴索钝性损伤手术后4h、1d、3d、5d、10d分离视神经,以激光共聚焦显微镜观察神经轴突受损程度及小胶质细胞的变化.结果 与对正常对照组比较,YFP小鼠术后4h损伤处视神经轴突断裂;术后1d视神经轴突开始出现念珠化;术后3d视神经轴突大部分念珠化;术后5d视神经轴突开始从念珠状转变为碎片状;术后10 d视神经轴突形成大量碎片.GFP小鼠与正常对照组相比,术后4h形成胶质瘢痕,静息态小胶质细胞开始大量出现;术后1d激活态小胶质细胞大量增多并开始覆盖受损区域;术后3d大量的激活态小胶质细胞基本覆盖了受损区域;术后5d、10 d虽然视神经的退行性病变持续恶化,但是小胶质细胞的数量基本保持稳定.结论 小鼠视神经受损后轴突发生不可逆的退行性病变,同时并伴随着小胶质细胞的激活和增多,说明小胶质细胞与视神经的退行性病变密切关联.     

视神经胶质细胞的培养及其特征观察

目的 体外培养、分离、纯化P2期小鼠视神经胶质细胞，并观察其生物学特性。方法 经颅开眶获取P2期小鼠管内段视神经2mm，组织块法培养，振荡法分离纯化，免疫组织化学方法鉴定，流式细胞仪检测纯度。结果 视神经星形胶质细胞体外迅速分裂增殖，少突胶质细胞生长缓慢，传代困难，振荡法分离纯化的细胞纯度高，星形胶质细胞GFAP染色阳性，阳性率96．2％，少突胶质细胞MBP染色阳性，阳性率96％。结论 组织块法培养、振荡法分离纯化P2期小鼠视神经星形和少突胶质细胞纯度高，是进一步研究视神经胶质细胞的结构和功能的可靠材料。     

慢性高眼压大鼠视神经中小胶质细胞／巨噬细胞的激活研究

目的探讨慢性高眼压大鼠视神经中小胶质细胞／巨噬细胞的激活分布情况。方法结扎两条巩膜上静脉建立慢性高眼压大鼠模型．应用OX-42单克隆抗体行免疫组化检测视神经中小胶质细胞／巨噬细胞的激活分布情况。结果对照眼视神经中小胶质细胞／巨噬细胞呈圆状、柱状．无明显树突样突起；慢性高眼压眼视神经中小胶质细胞／巨噬细胞呈阿米巴状、柱状，有树突样突起，细胞数量增加，术后第1周，视神经中小胶质细胞／巨噬细胞数量为49．61±8．04，3个400倍视野。此后视神经中小胶质细胞／巨噬细胞数量逐渐减少。术后第1周至第8周视神经中小胶质细胞／巨噬细胞的数量与同期对照眼相比差异有显著性（P〈0.05）。术后第12周，视神经中小胶质细胞／巨噬细胞的数量与同期对照眼相比差异无显著性（P〉0.05）。结论慢性高眼压可致视神经中小胶质细胞／巨噬细胞激活，细胞数量增加，但随时间延长逐渐降低。     

急性眼压升高所致视网膜、视神经及视交叉胶质细胞的早期反应北大核心CSCD

背景中枢神经系统以及视网膜中的胶质细胞与神经元关系十分紧密,胶质细胞在神经元损伤和修复过程中发挥着重要作用。急性眼压升高引起的视网膜、视神经及视交叉各部位胶质细胞的早期反应特点以及其与视神经损伤的关系目前尚不清楚。目的探讨大鼠视网膜、视神经及视交叉的胶质细胞对急性高眼压的早期反应,同时观察神经前体细胞标志物巢蛋白（nestin）在反应性胶质细胞中的表达。方法成年雌性Wistar大鼠9只,分为正常对照组3只和急性高眼压组6只,急性高眼压组大鼠采用右眼前房灌注生理盐水的方法升高大鼠眼压至110mmHg,持续60min。于术后第3天和第7天用过量麻醉法处死各组动物各3只,摘出眼球分离视神经和大脑标本,并制作冰冻切片。利用Nissl染色的方法测量高眼压眼视网膜内层厚度,观察视网膜和视交叉的大体形态。用BIU-tubu｜in免疫荧光染色法标记视神经内的视网膜神经节细胞（RGCs）轴突,用胶质纤维酸性蛋白（GFAP）和nestin双重标记显示视网膜、视神经及视交叉的胶质细胞反应,并对两组结果进行比较。结果正常大鼠的视网膜、视神经以及视交叉内均可见到一定量的GFAP阳性胶质细胞,但nestin的表达量很低。急性眼压升高后的第3天,视网膜内丛状层厚度明显变薄,RGCs数目较损伤前减少约46％。视网膜内胶质细胞GFAP的表达显著增加,细胞突起由神经纤维层伸展至整个视网膜,增生的胶质细胞内可见nestin的明显表达。视神经内RGCs轴突发生变性样改变,GFAP阳性胶质细胞内nestin的表达较眼压升高前明显增加。同损伤眼相对应的一侧视交叉的横断面积减小,出现大量星状GFAP和nestin共表达的胶质细胞。以上改变在眼压升高后第7天更趋明显。结论急性眼压升高早期即可引起RGCs的丢失及轴突的变性,视觉神经元改变的同时伴随胶质细胞的反应,增生的胶质细胞表达神经前体细胞的标志物。视网膜与视神经和视交叉的改变在时间上具有一定的同步性。     

急性眼压升高所致视网膜、视神经及视交叉胶质细胞的早期反应

背景 中枢神经系统以及视网膜中的胶质细胞与神经元关系十分紧密,胶质细胞在神经元损伤和修复过程中发挥着重要作用.急性眼压升高引起的视网膜、视神经及视交叉各部位胶质细胞的早期反应特点以及其与视神经损伤的关系目前尚不清楚. 目的 探讨大鼠视网膜、视神经及视交叉的胶质细胞对急性高眼压的早期反应,同时观察神经前体细胞标志物巢蛋白( nestin)在反应性胶质细胞中的表达. 方法 成年雌性Wistar大鼠9只,分为正常对照组3只和急性高眼压组6只,急性高眼压组大鼠采用右眼前房灌注生理盐水的方法升高大鼠眼压至110 mmHg,持续60 min.于术后第3天和第7天用过量麻醉法处死各组动物各3只,摘出眼球分离视神经和大脑标本,并制作冰冻切片.利用Nissl染色的方法测量高眼压眼视网膜内层厚度,观察视网膜和视交叉的大体形态.用βⅢ-tubulin免疫荧光染色法标记视神经内的视网膜神经节细胞(RGCs)轴突,用胶质纤维酸性蛋白(GFAP)和nestin双重标记显示视网膜、视神经及视交叉的胶质细胞反应,并对两组结果进行比较.结果 正常大鼠的视网膜、视神经以及视交叉内均可见到一定量的GFAP阳性胶质细胞,但nestin的表达量很低.急性眼压升高后的第3天,视网膜内丛状层厚度明显变薄,RGCs数目较损伤前减少约46％.视网膜内胶质细胞GFAP的表达显著增加,细胞突起由神经纤维层伸展至整个视网膜,增生的胶质细胞内可见nestin的明显表达.视神经内RGCs轴突发生变性样改变,GFAP阳性胶质细胞内nestin的表达较眼压升高前明显增加.同损伤眼相对应的一侧视交叉的横断面积减小,出现大量星状GFAP和nestin共表达的胶质细胞.以上改变在眼压升高后第7天更趋明显.结论 急性眼压升高早期即可引起RGCs的丢失及轴突的变性,视觉神经元改变的同时伴随胶质细胞的反应,增生的胶质细胞表达神经前体细胞的标志物.视网膜与视神经和视交叉的改变在时间上具有一定的同步性.     

小鼠视神经损伤后视神经小胶质细胞数目和形态变化

目的：研究小鼠视神经损伤后不同时间点视神经小胶质细胞的数目与形态变化。方法：实验研究。选取32只成年雄性健康CX3CR1—/GFP转基因杂交小鼠,按照随机数字表法将小鼠随机分为正常对照组、视神经损伤1、7、14 d组,每组8只。视神经损伤组均在左眼建立视神经夹伤模型,右眼不处理,正常对照组不做任何处理。分别于上述时间点制备小鼠视神经冰冻切片,每根视神经取3张切片（30 μm）,采用共聚焦显微镜在距离眼球端500 μm处拍摄图像,比较小胶质细胞的数量和形态变化。4组小胶质细胞数目比较采用单因素方差分析。结果：正常对照组、视神经损伤1、7和14 d组的视神经小胶质细胞数目分别为（438±16）个/mm2、（323±15）个/mm2、（1 252±107）个/mm2、（1 474±113）个/mm2。视神经损伤7、14 d组小胶质细胞数量明显多于正常对照组和视神经损伤1 d组,差异均有统计学意义（均 P<0.001）。正常对照组的视神经小胶质细胞均匀分布,细胞核较小,分枝细长并向四周伸展。视神经损伤1 d组,小胶质细胞分枝数量减少,细胞核形态变化不明显。损伤7 d组的视神经小胶质细胞大量激活,排列较紊乱,存在少量细胞聚集现象,分枝短而粗,且越靠近细胞核分枝越粗,细胞核体积明显增大。视神经损伤14 d组,视神经小胶质细胞形态与损伤7 d组类似。结论：小鼠视神经夹持损伤后,视神经小胶质细胞初期数目减少,随着损伤时间延长,小胶质细胞数目大量增加,且形 态由分枝状变为阿米巴样。     

Human optic nerve fiber count and optic disc size.

In the optic nerve head, the optic nerve fibers are represented by the neuroretinal rim. The rim area showing a high interindividual variability is positively correlated with the optic disc size. This study was performed to address the question of whether, in addition to having a larger neuroretinal rim, eyes with large optic discs also have a higher count of optic nerve fibers compared to eyes with small optic nerve heads. Histologic semithin sections of 72 optic nerves of 56 cornea donors were histomorphometrically evaluated using a computerized image analyzer. The optic nerve fiber count increased significantly (P = 0.01) with enlarging optic disc size. The nerve fiber count was positively correlated with the retrobulbar optic nerve cross section area. It decreased with advancing age, with a mean annual loss of about 4,000 fibers. The nerve fiber density per disc area decreased with increasing optic disc area. Mean and median of the minimal nerve fiber diameter was larger in older subjects. The results may indicate that the optic nerve fiber count, and the anatomic reserve capacity in progressive optic neuropathies, are higher in eyes with large optic discs than in eyes with small optic nerve heads. The optic nerve fiber population decreased with advancing age. This is important for progression, pseudoprogression, and prognosis of optic neuropathies. Optic nerve fiber crowding is more marked in eyes with small optic discs than in eyes with large optic nerve heads. The age-related loss of predominantly small optic nerve fibers can potentiate the optic nerve atrophy in glaucoma and Alzheimer's disease, with both damaging preferentially large axons.     

青光眼视神经损害的三要素及其盘沿丢失的识别

诊断青光眼视神经损害的三要素为盘沿丢失、视网膜神经纤维层缺损（RNFLD）及视盘线状出血。三要素中如有两要素改变应诊断为视神经损害。对于盘沿丢失已往的教科书中均无明确描述,笔者认为识别盘沿丢失必须首先认识正常盘沿形态及其影响因素。大多数的正常盘沿形态符合ISNT法则,生理性大视杯也符合该法则。不符合ISNT法则者为盘沿丢失,或者为正常盘沿形态变异。后者如部分小视盘下方盘沿可比上方盘沿窄,判断是否上、下方盘沿丢失时应将其与鼻侧盘沿进行比较;横椭圆视盘鼻侧盘沿较宽,应上、下盘沿比较;视盘主干血管发出位置偏位、视盘倾斜也会影响盘沿形态。如果参照ISNT法则认识正常盘沿变异因素,就不难发现盘沿丢失。然而不是所有的盘沿丢失均为青光眼所致,应鉴别非青光眼性视神经损害。     

Histomorphometric analysis of optic nerve changes in experimental glaucoma

PURPOSE: To assess relative changes in different tissue components of optic nerve and their relationship to nerve fiber loss in the experimental monkey model of glaucoma. METHODS: Chronic intraocular pressure (IOP) elevation was induced by laser trabeculoplasty in the right eye of eight monkeys (Macaca fascicularis). Both experimental right optic nerves and control left optic nerves were studied. Histomorphometric analysis was performed on optic nerve cross-sections using bright field microscopy with camera lucida. Cross-sectional areas of optic nerve tissue components were estimated by point counting. Nerve fiber density was estimated by unbiased random sampling. Nerve fiber number was calculated by multiplying nerve fiber density with neuroglial area. RESULTS: Varying degrees of nerve fiber loss were seen in eight optic nerves with chronic IOP elevation. More than 50% nerve fiber loss was noted in four of eight experimental optic nerves. In these severely affected optic nerves, total optic nerve area was significantly decreased compared with control optic nerves. Among the optic nerve tissue components, only the ratio of myelinated fiber area to total optic nerve area was significantly decreased. The ratio of extraaxonal area to total optic nerve area was significantly increased, whereas the ratio of interfascicular septal area to total optic nerve area did not change significantly. For all optic nerves, differences in nerve fiber count between control and experimental optic nerves showed the strongest correlation with differences in myelinated fiber area, followed by differences in extraaxonal area and total optic nerve area. CONCLUSION: This histomorphometric study suggests the validity of the experimental monkey model of glaucoma in studying changes occurring in the nonaxonal optic nerve tissue components in human glaucomatous optic neuropathy. Glial scar tissue area was significantly increased in optic nerves with severe glaucomatous damage. Although a decrease in total optic nerve area was observed, among the optic nerve tissue components only myelinated nerve fiber area decreased significantly. Myelinated nerve fiber area also showed the strongest association with nerve fiber loss in experimental glaucoma.     

Evaluation of the Optic Nerve Complex in the Orbit Using Coronal Fast Magnetic Resonance Imaging

Recently available coronal fast magnetic resonance imaging (MRI) has very high spatial resolution with good contrast between the optic nerves and cerebrospinal fluid (CSF). The aim of this study was to evaluate the diagnostic value of coronal fast imaging in optic nerve diseases. Thirty-five patients with various Neuro-ophthalmic conditions including 9 with optic neuritis, 6 with optic atrophy, 5 with glaucoma, 4 with segmental optic nerve hypoplasia and 11 with other optic neuropathies including orbital apex syndrome were evaluated with the three-dimensional fast imaging employing steady-state acquisition (FIESTA) sequence in addition to standard MRI protocols. The optic nerve complexes were evaluated on coronal images of the orbits. Detailed demonstration of the optic nerve complex—the optic nerve, the perineural CSF space and dural sheath—could be readily obtained with FIESTA sequence. The acute phase of both optic neuritis and perineuritis showed enlargement of the perineural CSF space; the optic nerve was swollen in optic neuritis but not in perineuritis. Cases of optic atrophy and glaucoma showed perineural CSF space enlargement with normal optic sheath circumference and a thinner optic nerve, while optic nerve hypoplasia showed a smaller dural sheath circumference without perineural CSF space enlargement. In the cases of orbital apex syndrome optic nerve compression by the extraocular muscles was clearly shown. Coronal FIESTA imaging of the orbit is capable of delineating detailed structural changes in the optic nerve complex and is of diagnostic value for the differentiation of optic nerve diseases.     

Optic nerve fiber count and diameter of the retrobulbar optic nerve in normal and glaucomatous eyes

Background: The caliber of the retrobulbar optic nerve and the count of optic nerve fibers vary considerably in normals. The diameter of the retrobulbar optic nerve also decreases with optic nerve atrophy. This study aimed to determine the relationship between the caliber of the optic nerve and the optic nerve fiber count. Methods: We counted the optic nerve fibers and measured the diameter of histological cross sections of the optic nerve for 56 normal subjects and 23 patients with absolute glaucoma. Results: The optic nerve fiber count increased significantly (P<0.0001) by 777 000 fibers for every millimeter increase in retrobulbar optic nerve diameter, starting at a baseline diameter of 1.89 mm. Conclusion: Using this linear regression equation, the optic nerve fiber count can be estimated in routine histology by measuring the optic nerve diameter. Taking into account a fixation-induced tissue shrinkage, this method may also give some indication of the optic nerve fiber count intravitally, when, for eyes with opaque optic media, the diameter of the retrobulbar optic nerve has been measured by imaging techniques. Greater retrobulbar optic nerve caliber may indicate greater structural reserve capacity.     

Optic nerve pit

Optic nerve pits are an uncommon congenital anomaly of the optic nerve head. Pits are generally recognized to represent an atypical form of optic nerve coloboma. The appearance of optic nerve pits can be quite variable and may simulate other anomalies of the optic nerve head, such as glaucoma or optic nerve tumor. Visual loss is present in a significant number of cases. Arcuate scotomas and a serous macular detachment have been associated with pits of the optic nerve. The mechanism for development of the serous maculopathy is not well understood.     

Optic nerve head microvasculature of the rabbit eye.

Vascular luminal castings of rabbit eyes were microdissected and studied with scanning electron microscopy to elucidate the three-dimensional angioarchitecture of the optic nerve head. Using sequential microdissection, an incomplete arterial circle was identified as terminal branches of two to three short posterior ciliary arteries around the optic nerve head. Several recurrent branches from the arterial circle form a pial arterial network. This pial system supplies the optic nerve head microvasculature and receives numerous venules from them. The only large vessel to enter the optic nerve is a central retinal artery that has few branches within the optic nerve and provides several branches at the surface of the optic disc. Moderately numerous vessels connect the retinal and ciliary vascular layers within the optic nerve head. Few arterioles to the optic nerve head arise from the choroid; however, there are a small number of capillary and numerous venous connections between them. These results indicate that the principal blood supply of the rabbit optic nerve head is derived from the short posterior ciliary arteries by the arterial circle. The retinal arteries contribute to the surface vasculature of the optic nerve head. The pial system also plays a significant role in both supply and drainage of the rabbit optic nerve head.     

人眼视神经组织形态学研究视神经纤维计数和直径及视盘面积的测定

目的通过测量正常人眼视神经纤维数量、直径及视盘面积，为青光眼视神经损害研究奠定基础，并对其相互关系进行分析。方法应用一种计算机图像分析系统对15只正常人眼视神经断面和视盘进行检测。结果平均视神经纤维数为（10.08±1.61）×10⁵，神经纤维平均直径为（0.99±0.04）μm，平均视盘面积为（2.28±0.61）mm²。视神经纤维数随神经断面面积的增加而增加，而与视盘面积无关。结论本研究为临床推测视神经损害的预后及进一步研究青光眼的神经损害奠定了一定的基础。(中华眼底病杂志,1999,15:16-19)     

Regional optic nerve damage in experimental mouse glaucoma

PURPOSE: To assess the relationship between regional variation of axon loss and optic nerve head anatomy in laser-induced experimental glaucoma in the mouse. METHODS: Experimental glaucoma was induced unilaterally in eight NIH Swiss black mice. Intraocular pressure (IOP) was measured for 12 weeks, and the mice were killed. The eyes were enucleated, and both optic nerves were dissected and processed conventionally for electron microscopy. Low- and high-magnification images of the optic nerve cross sections 300 microm posterior to the globe were collected systematically and masked before analysis. For each nerve, cross-sectional area was measured in low-magnification micrographs. Axon number and density were determined in the high-magnification micrographs. Loss of axonal density was compared between the superior and inferior and nasal and temporal areas of the optic nerve cross section. Additional cross-section micrographs were collected at 10- or 20-microm intervals throughout the optic nerve head. RESULTS: In the treated (glaucoma) eyes, mean IOP was 44% higher than that in the control eyes. The optic nerve cross-sectional area, mean axonal density, and total axonal number were significantly less than those in the control eyes (P < 0.01 for each). Axon loss in the superior optic nerve was greater than in the inferior optic nerve in each glaucomatous eye (P = 0.012). The ratio of axonal density in the superior and inferior optic nerve (superior-to-inferior [S/I] ratio) in all treated eyes was <1.0 and significantly lower than that in the control eyes (P = 0.012). The central retinal vessels occupied approximately 20% of the central optic nerve head cross-sectional area, gradually shifted position ventrally as they progressed toward the scleral foramen (the mouse does not have a lamina cribrosa), and exited the inferior retrobulbar optic nerve adjacent to the posterior of the globe. CONCLUSIONS: Ocular hypertension in the mouse eye sufficient to cause optic nerve damage induces preferential loss of superior optic nerve axons. Optic nerve axon loss appeared less among the axons that were near the major optic nerve blood vessels at the scleral foramen. Topographic differences in optic nerve axon loss should be considered when evaluating optic nerve damage in experimental laser-induced glaucoma in the mouse.     

晶状体损伤对视神经损伤后再生影响的研究

目的观察单纯视神经损伤及视神经损伤联合晶状体损伤后视神经中Nogo-A mRNA及Nogo-A的表达,探讨晶状体损伤促进视神经损伤后再生的机制。方法 66只雄性Wistar大鼠随机分为正常对照组(A组,6只)、单纯视神经损伤组(B组,30只)和视神经损伤联合晶状体损伤组(C组,30只)。分别于造模后7d、14d、21d处死大鼠2只(A组)、10只(B组)、10只(C组),光镜下观察视神经的病理变化,免疫组织化学染色检测Nogo-A表达情况,采用逆转录-聚合酶链反应(RT-PCR)、半定量分析不同组视神经Nogo-A mRNA的表达。结果大鼠正常视神经中表达Nogo-A mRNA及Nogo-A,但表达量较低;损伤视神经后7d Nogo-A mRNA的表达量显著升高,至伤后21d B组及C组均维持较高的水平。B组损伤后7d Nogo-A表达阳性的细胞数开始增多(136.80±3.94),与A组比较差异有统计学意义(P<0.05),并保持高表达;C组损伤后21d Nogo-A的表达较B组低,差异有统计学意义(P<0.05)。结论视神经损伤后髓鞘相关抑制因子Nogo-A表达增高,晶状体损伤促进视神经再生的机制可能与Nogo-A有关。