N-亚硝基-N-甲基脲诱导视网膜变性小鼠模型的特征

目的探讨N-亚硝基-N-甲基脲（MNU）诱导的小鼠视网膜退行性病变的形态和电生理特征。方法实验研究。32只5周龄的成年C57/BL小鼠随机分为对照组和MNU造模组,分别腹腔注射0.9%氯化钠溶液和MNU（60 mg·kg-1）。在给药后3、7和14 d取视网膜,免疫荧光染色观察光感受器形态、氧化损伤情况和神经节细胞的数量。电镜观察细胞核、线粒体和带状突触（synaptic ribbon）的超微结构。Ganzfeld视网膜电图（ERG）检测暗适应最大混合反应。采用独立样本t检验进行数据分析。结果免疫荧光显示：注射MNU后外核层（ONL）的厚度逐渐减小,OPN1SW标记的光感受器细胞的外节（OS）逐渐损伤,GFAP标记的Müller细胞增生明显,ONL层硝基酪氨酸（Nitrotyrosine）着色增多提示MNU能导致氧化损伤。Brn-3a标记的神经节细胞数量减少不明显。扫描电子显微镜显示：MNU处理后,光感受器细胞的核呈浓染色,线粒体和带状突触消失。ERG结果显示：MNU处理后3 d最大混合反应的a波和b波振幅下降。结论MNU导致视网膜外核层和外丛状层的凋亡,电生理表现和视网膜色素变性疾病一致。     

N-甲基-N-亚硝脲对大鼠视网膜光感受器的毒性作用

目的:观察N-甲基-N-亚硝脲(N-methyl-N-nitrosourea,MNU)对SD大鼠视网膜光感受器细胞的毒性作用。方法:雌性SD大鼠100只,分17组,正常对照组4只,其余组各6只。在大鼠生后50 d,分别一次腹腔注射MNU 50 mg／kg、60 mg／kg、70 mg／kg和80 mg／kg。在MNU处理后24、48、72 h和7 d处死大鼠,取眼球,做组织学检查。结果:不同剂量的MNU均引起中心视网膜和周边视网膜损伤,其损害的程度与MNU的剂量呈正比。作用24 h后,可见视网膜光感受器细胞核固缩、破坏及光感受器外节部定向紊乱;48 h或72 h后,可见光感受器细胞丧失;7 d后,外颗粒层和光感受层几乎完全消失。结论:MNU对大鼠视网膜光感受器细胞有选择性的毒性作用,该作用呈剂量和时间依赖性。     

N-甲基-N-亚硝脲对猫视网膜光感受器细胞损害的研究

背景合理的视网膜色素变性（RP）动物模型的建立方法是进行RP干预和治疗的重要工具和手段。研究证实,N-甲基-N-亚硝脲（MNU）可造成哺乳动物光感受器细胞的选择性损害,但是否MNU可用于建立RP动物模型的报道较少。目的评估MNU对猫视网膜光感受器细胞的毒性损害作用。方法20只2岁龄的猫一次性股静脉注射MNU,并按照注射剂量的不同分为20、25、30、35、40mg／kgMNU组,每组4只。另外4只猫股静脉注射等量生理盐水作为对照组。MNU注射后每日观察实验猫的行为变化、瞳孔大小及对光反射情况,分别于注射后24h、72h、7d和14d用静脉注射过量的质量分数2％戊巴比妥钠处死实验猫,眼球摘除后制备视网膜切片进行组织病理学检查,评估不同剂量MNU对视网膜光感受器的影响。结果不同剂量MNU组的实验猫注射MNU7d后瞳孔散大,对光反射迟钝。MNU注射24h,猫视网膜光感受器细胞的损害以核固缩和排列紊乱为主,MNU注射72h,视网膜光感受器细胞的损害以外核层变薄和细胞碎裂为主,MNU注射7d后,40mg／kg注射组的实验猫均死亡,光感受器细胞层仅存在极少量细胞,MNU注射14d,视网膜光感受器细胞层均完全消失。各组视网膜损害程度与注射MNU剂量有关。结论MNU可以造成猫视网膜光感受器细胞的严重损害,MNU对视网膜光感受器的作用呈时间和剂量依赖性。     

金钠多、灯盏花素对N-甲基-N-亚硝脲诱导SD大鼠视网膜变性的保护作用

目的　观察金钠多 (Gin)、灯盏花素 (Bre)对N 甲基 N 亚硝脲 (MNU)诱导SD大鼠视网膜变性的保护作用及机制。方法　雌性SD大鼠随机分为正常对照组、模型组、Gin组和Bre组。其中Gin又分大剂量和中剂量组 ,Bre分大剂量、中剂量和小剂量组。于生后 47d开始腹腔注射给药 ,每日 1次 ,连续给药 4d和 10d ,并于生后 50d腹腔注射MNU 60mg/kg。在MNU处理 2 4h和 7d后处死动物 ,取眼球。通过视网膜形态学分析测量周边视网膜的总厚度 ,TUNEL试剂盒检测光感受器细胞凋亡。结果　MNU处理 7d后 ,模型组周边视网膜的总厚度为 3 6μm ,Gin组和Bre组分别为 44、3 7、58、43和 3 9μm。MNU处理 2 4h后 ,模型组周边视网膜的光感受器细胞凋亡指数为 (3 8 0± 3 6) % ,Gin组和Bre组分别为 (2 6 3± 2 7) %、(3 7 4± 2 9) %、(19 4± 1 9) %、(2 8 0± 3 0 ) %和 (3 6 9± 2 1) %。结论　Gin和Bre对MNU引起的周边视网膜损伤有一定的保护作用 ,呈剂量依赖性 ,其作用机制是通过抑制光感受器细胞发生凋亡。但二者对中心视网膜均无保护作用     

N-甲-N-亚硝脲对大鼠视网膜光感受器的毒性作用

目的观察N-甲基-N-亚硝脲(N-methyl-N-nitrosourea,MNU)对SD大鼠视网膜光感受器细胞的毒性作用.方法雌性SD大鼠100只,分17组,正常对照组4只,其余组各6只.在大鼠生后50 d,分别一次腹腔注射MNU 50mg/kg、60mg/kg、70mg/kg和80mg/kg.在MNU处理后24、48、72 h和7 d处死大鼠,取眼球,做组织学检查.结果不同剂量的MNU均引起中心视网膜和周边视网膜损伤,其损害的程度与MNU的剂量呈正比.作用24 h后,可见视网膜光感受器细胞核固缩、破坏及光感受器外节部定向紊乱;48 h或72 h后,可见光感受器细胞丧失;7 d后,外颗粒层和光感受层几乎完全消失.结论MNU对大鼠视网膜光感受器细胞有选择性的毒性作用,该作用呈剂量和时间依赖性.     

杞菊地黄汤对MNU诱发的大鼠视网膜变性基因表达谱的影响

目的:观察杞菊地黄汤防治MNU诱发大鼠视网膜变性的基因表达谱变化,探索其作用的分子机制。方法:30只大鼠分为3组:药物组(杞菊地黄汤灌胃 MNU皮下注射)、模型组(生理盐水灌胃 MNU皮下注射)和正常组(生理盐水灌胃)。造模后12h,取视网膜进行基因芯片分析和RT-PCR检测。并用GO(gene ontology)分类和信号通路分析等方法对差异表达的基因进行分析。结果:模型组/正常组和模型组/药物组中分别有75个和118个差异表达基因,这些基因多与信号转导、发育、免疫和防御、凋亡等生物过程有关,主要涉及到MAPK、Toll样受体和凋亡信号通路。结论:在MNU诱导的大鼠视网膜变性中,杞菊地黄汤能特异性拮抗数个信号通路中的基因表达。     

MNU诱导视网膜外层退行变性的细胞电生理和超微结构特征

目的：观察N-甲基-N-亚硝基脲（MNU）诱导的小鼠视网膜外层变性损伤的细胞电生理特征和超微结构变化。方法：实验研究。通过腹腔注射PBS和MNU,将C57/BL小鼠60 只随机分为对照组和MNU造模组。运用膜片钳电生理技术,观察位于外丛状层的双极细胞的电生理活动。用透射电子显微镜观察视网膜的超微结构。结果：膜片钳结果显示,给MNU后7 d,ON型双极细胞（ON-BC）对药物氨基（环丙基）（ 4-膦酰苯基）乙酸电生理反应完全消失,而OFF型双极细胞（OFF-BC）对药物α-氨基-3-羟基-5-甲基-4-异恶唑丙酸的刺激仍有电生理反应。给MNU后2 d,位于光感受器细胞外节（OS）的盘膜结构变薄。给MNU后5 d,OS消失,位于光感受器细胞内节（IS）的线粒体等细胞器严重肿胀。给MNU后10 d,IOS消失,光感受器细胞的核层变薄,核呈不同程度的浓染。下游的双极细胞核周间隙增宽,在双极细胞胞浆中有大量的自噬体。结论：MNU对ON型信号通路的损伤,比对OFF型信号通路的损伤要严重一些。MNU导致的视网膜损伤主要位于外侧（包括外核层和外丛状层）。MNU致光感受器细胞损伤的机制是凋亡。     

骨髓间充质干细胞(MSCs)对N-甲基-N-亚硝脲(MNU)诱导的C57BL小鼠视网膜变性的治疗作用

目的 观察骨髓间充质干细胞(mesenchymal stem cells,MSCs)对N-甲基-N-亚硝脲(N-methyl-N-nitrosourea,MNU)诱导的C57BL小鼠视网膜色素变性(retinitis pigmentosa,RP)的治疗作用.方法 应用不同剂量(30 mg·kg-1、45 mg·kg-1、60 mg·kg-1、75 mg·kg-1、90 mg·kg-1)的MNU腹腔注射给予C57BL小鼠和MNU作用不同时间(1d、3d、7d)后,通过视网膜电图(electroretinogram,ERG)和HE染色检测小鼠视网膜的电生理功能和组织形态变化,优化建立稳定的RP动物模型的最佳条件;在此动物模型的基础上,经玻璃体内注射和尾静脉注射给予MSCs移植,并应用ERG和HE染色评估MSCs对MNU诱导的RP的治疗作用.结果 与对照组相比,30 mg·kg-、45mg·kg-1剂量的MNU可引起视网膜形态和功能的轻微损伤,而60 mg·kg-1及其以上剂量的MNU可使视网膜ERG波幅明显降低(均为P ＜0.001),视网膜外核层(outer nuclear layer,ONL)厚度明显变薄(P ＜0.001),损伤严重;与对照组相比,60 mg·kg-的MNU作用后1d和3d,视网膜ERG波形开始降低,形态结构开始出现ONL厚度变薄的损伤,作用7d时,ERG波形呈现熄灭型(均为P＜0.001),ONL厚度明显变薄(P ＜0.001),内外核层融合,损伤严重.与MNU单独作用组相比,60 mg·kg-1 MNU作用1d后给予MSCs移植,7d后MSCs组内ONL厚度增加(P ＜0.001),视网膜ERG波形趋于恢复(均为P＜0.001).结论 MSCs移植对MNU诱导的视网膜退行性变有一定的治疗作用.     

N-甲基-N-亚硝脲诱导大鼠视网膜光感受器细胞凋亡

目的 探讨N一甲基一N一亚硝脲(MNu)对大鼠视网膜光感受器细胞毒性作用的机制。 方法 将生后50 d的雌性SD大鼠30只分别按60 mg／kg的剂量一次性腹腔注射MNu。在注射MNU 12、24、48、72 h和7 d后，颈椎脱臼法处死大鼠，取出眼球，做病理切片。另6只生后50 d的雌性sD大鼠为正常对照。用TuNEI一试剂盒和透射电镜检测光感受器细胞凋亡；免疫组织化学方法检测MNU作用不同时间视网膜细胞内增生细胞核抗原(PcNA)、弹性蛋白和胶质纤维酸蛋白(GFAP)的表达。 结果 MNu作用后极部视网膜光感受器细胞12、24、48、72 h和7 d后的凋亡指数分别是(33．6±2．3)％、(46．5±5．7)％、(20·l±5·3)％、(8-2±3·6)％和(2．O±O．8)％。在MNu作用后24 h，大部分光感受器细胞出现核固缩；24 h后，内颗粒层及内颗粒层和脉络膜之间有PcNA表达，72 h达高峰，7 d后明显减少；24 h后，内颗粒层和外颗粒层开始出现GFAP和弹性蛋白的阳性表达，72 h达高峰，7 d后明显减少。 结论 MNu可选择性地诱导视网膜光感受器细胞发生凋亡及引起Mnller细胞增生。 （中华眼底病杂志，2004，20：33-36）     

兔眼视网膜下注射N-甲基右旋天冬氨酸诱导视网膜变性的组织病理学研究

目的研究视网膜下注射兴奋性氨基酸N-甲基右旋天冬氨酸（NMDA）对神经细胞变性的作用。方法取12只1个月龄有色家兔,视网膜下注射10μl（30mmol／L）NMDA（溶剂为DMEM-F12）,形成视网膜隆起,在注射12、24、48h及1周后分别处死家兔,取其视网膜组织进行免疫组织化学检测和电镜观察。应用抗Calretinin、Calbindin、PKCα抗体,分别标记视网膜无长突细胞、水平细胞及视杆双极细胞;采用原位缺口末端标记技术（TUNEL）技术标记凋亡细胞。结果损伤早期（12～24h）,实验组视网膜可见散在细胞核固缩浓染的光感受器细胞,并有无长突细胞和神经节细胞的早期严重变性;中期（48h）视网膜各层神经元均出现病理性改变;损伤晚期（1周）视网膜各层细胞数目明显减少。损伤早期,TUNEL技术标记的阳性细胞位于视网膜各层。免疫组织化学和形态学计量资料显示视网膜下注射NMDA后,水平细胞、无长突细胞及神经节细胞数目明显减少,视杆双极细胞数目基本无变化。超微结构观察显示有凋亡、坏死、水肿变性及混合型细胞死亡等多种变性形式。结论视网膜下聚集NMDA时,光感受器细胞、水平细胞、视杆双极细胞、无长突细胞及神经节细胞均表现为视网膜兴奋性毒性反应,与以往体内及体外研究结果显示的仅有内核层神经元死亡情况不同。     

氩离子激光光凝治疗近视性视网膜变性疗效分析

目的 分析氩激光光凝对近视性视网膜变性的疗效。方法 充分散瞳，用双目间接眼底镜Mainster镜及三面镜检查眼底，对发现的视网膜变性和／或裂孔进行氩激光光凝治疗。结果 133例(165只眼)，其中132只眼为高度近视，占80％。129只眼一次性治愈，其余患眼分别补激光l～2次后治愈，未有发生视网膜脱离者。结论 眼底激光光凝可以有效治疗近视性视网膜变性，能预防该类病人视网膜脱离的发生。     

Dietary docosahexaenoic acid protects against N-methyl-N-nitrosourea-induced retinal degeneration in rats

The effect of dietary intake of specific types of fatty acids on retinal degeneration due to N-methyl-N-nitrosourea (MNU)-induced photoreceptor cell apoptosis was evaluated. Fifty-day-old female Sprague-Dawley rats were given a single intraperitoneal injection of 50 mg kg(-1) body weight of MNU, and were then switched to one of five different diets containing the following fatty acids at the following weight percentages: 10% linoleic acid (LA); 9.5% palmitic acid (PA) and 0.5% LA; 9.5% eicosapentaenoic acid (EPA) and 0.5% LA; 4.75% EPA, 4.75% docosahexaenoic acid (DHA) and 0.5% LA; or 9.5% DHA and 0.5% LA. When rats developed MNU-induced mammary tumors with a diameter of > or =1 cm, or at the termination of the experiment (20 weeks after MNU injection), retinal tissue samples were obtained and examined. Incidence and severity of retinal damage were compared by histologic examination. MNU-induced retinal degeneration was prevented in rats fed the diet containing 9.5% DHA (4.75% DHA was less effective), whereas it was accelerated in rats fed the 10% LA diet. Over the course of the 20-week experimental period, the fatty acid composition of serum reflected differences in dietary fatty acids. The present results indicate that a diet containing 9.5% DHA can counteract MNU retinotoxicity in the rat retina. DHA may play a role in protection against MNU-induced photoreceptor cell apoptosis in the rat retina.     

Identification of novel retinal target genes of thyroid hormone in the human WERI cells by expression microarray analysis

Using the human WERI-Rb1 cell line as a model system, we performed a genome-wide search for retinal target genes of thyroid hormone (TH) via expression microarray analysis followed by quantitative real-time RT-PCR verification. We identified 12 novel retinal targets of TH, including 10 up-regulated genes (OPN1MW, OPN1LW, TIMP3, RP1L1, GNGT2, CRX, ARR3, GCAP1, IMPDH1, and PDE6C) and 2 down-regulated genes (GNGT1 and GNB3). In addition, we found a number of novel TH-targets that are not currently known to be retinal genes. This is the first report of human retinal targets regulated by thyroid hormone.     

乳酸对鼠视网膜血管内皮生长因子表达的影响

目的 观察不同浓度乳酸对培养的大鼠视网膜血管内皮生长因子(VEGF)表达的影响.方法 2周龄Sprague-Dawley大鼠36只,根据培养液中乳酸含量分为10、20、30 mmol/L乳酸组,每组均为12只大鼠.处死大鼠,摘出眼球剥离视网膜,将视网膜置入插入式培养皿中培养24 h.培养皿中培养液分别为含10、20、30 mmol/L乳酸的Dulbecco改良Eagle培养液+2%胎牛血清.光学显微镜观察视网膜结构、实时荧光定量聚合酶链反应(RT-PCR)和蛋白质免疫印迹(Western blot)检测VEGF的表达.结果 光学显微镜组织病理学观察结果显示,视网膜层次清晰,结构完整,未见明显细胞溶解和坏死.RT-PCR检测结果显示,10、20、30 mmol/L乳酸组VEGF mRNA表达量分别为0.74±0.06、0.99±0.12、1.45±0.17;Western blot检测结果显示,10、20 mmol/L乳酸组和30 mmol/L乳酸组视网膜VEGF表达量分别为0.34±0.15、0.54±0.16、0.93±0.23.RT-PCT和Western blot检测结果均显示30 mmol/L乳酸组较10 mmol/L乳酸组VEGF表达明显升高.结论 乳酸诱导视网膜VEGF表达有浓度依赖性.     

Iron homeostasis and toxicity in retinal degeneration

Iron is essential for many metabolic processes but can also cause damage. As a potent generator of hydroxyl radical, the most reactive of the free radicals, iron can cause considerable oxidative stress. Since iron is absorbed through diet but not excreted except through menstruation, total body iron levels buildup with age. Macular iron levels increase with age, in both men and women. This iron has the potential to contribute to retinal degeneration.

Here we present an overview of the evidence suggesting that iron may contribute to retinal degenerations. Intraocular iron foreign bodies cause retinal degeneration. Retinal iron buildup resulting from hereditary iron homeostasis disorders aceruloplasminemia, Friedreich's ataxia, and panthothenate kinase-associated neurodegeneration cause retinal degeneration. Mice with targeted mutation of the iron exporter ceruloplasmin have age-dependent retinal iron overload and a resulting retinal degeneration with features of age-related macular degeneration (AMD). Post mortem retinas from patients with AMD have more iron and the iron carrier transferrin than age-matched controls.

Over the past 10 years much has been learned about the intricate network of proteins involved in iron handling. Many of these, including transferrin, transferrin receptor, divalent metal transporter-1, ferritin, ferroportin, ceruloplasmin, hephaestin, iron-regulatory protein, and histocompatibility leukocyte antigen class I-like protein involved in iron homeostasis (HFE) have been found in the retina. Some of these proteins have been found in the cornea and lens as well. Levels of the iron carrier transferrin are high in the aqueous and vitreous humors. The functions of these proteins in other tissues, combined with studies on cultured ocular tissues, genetically engineered mice, and eye exams on patients with hereditary iron diseases provide clues regarding their ocular functions.

Iron may play a role in a broad range of ocular diseases, including glaucoma, cataract, AMD, and conditions causing intraocular hemorrhage. While iron deficiency must be prevented, the therapeutic potential of limiting iron-induced ocular oxidative damage is high. Systemic, local, or topical iron chelation with an expanding repertoire of drugs has clinical potential.     

Subretinal transplantation of bone marrow mesenchymal stem cells delays retinal degeneration in the RCS rat model of retinal degeneration

Because there is no effective treatment for this retinal degeneration, potential application of cell-based therapy has attracted considerable attention. Several investigations support that bone marrow mesenchymal stem cells (MSCs) can be used for a broad spectrum of indications. Bone marrow MSCs exert their therapeutic effect in part by secreting trophic factors to promote cell survival. The current study investigates whether bone marrow MSCs secrete factor(s) to promote photoreceptor cell survival and whether subretinal transplantation of bone marrow MSCs promotes photoreceptor survival in a retinal degeneration model using Royal College of Surgeons (RCS) rats. In vitro, using mouse retinal cell culture, it was demonstrated that the conditioned medium of the MSCs delays photoreceptor cell apoptosis, suggesting that the secreted factor(s) from the MSCs promote photoreceptor cell survival. In vivo, the MSCs were injected into the subretinal space of the RCS rats and histological analysis, real-time RT-PCR and electrophysiological analysis demonstrated that the subretinal transplantation of MSCs delays retinal degeneration and preserves retinal function in the RCS rats. These results suggest that MSC is a useful cell source for cell-replacement therapy for some forms of retinal degeneration.     

利用锥体细胞失功能大鼠和先天性静止性夜盲大鼠对视锥与视杆通路振荡电位的分离研究

背景 振荡电位(OPs)是评估视网膜缺血缺氧性疾病视网膜功能变化的重要工具,利用视网膜退行性病变动物模型对视锥、视杆通路起源的OPs特点进行研究非常重要. 目的 在两种自发性视网膜退行性病变模型大鼠中分离视锥、视杆通路,对比分析视杆、视锥通路起源的OPs波的特点. 方法 采用雄性SD大鼠、锥体细胞失功能(RCD)大鼠、先天性静止性夜盲(CSNB)大鼠各6只,以RETI-scan视觉生理记录系统分别在暗适应(12h)和明适应(10 min)条件下,用不同强度的刺激光(-35、-25、-15、-5、0、5 db)进行刺激,记录各组大鼠的闪光视网膜电图(FERG),通过Matlab 7.0的Butterworth滤波提取OPs,采用快速傅里叶变换(FFT)对所得OPs进行频谱分析.结果 暗适应条件下SD大鼠和RCD大鼠的ERG均可见a波和b波,但CSNB大鼠b波阙如;明适应条件下,SD大鼠和CSNB大鼠可见b波,但RCD大鼠各波阙如.暗适应较高刺激光强度下,SD大鼠和RCD大鼠均有低频(主频)和高频(次频)两个明显的频峰,分别为75 ～ 110 Hz、90～120 Hz和90～ 120 Hz、110 ～ 135 Hz;不同刺激光强度下,CSNB大鼠只有一个频峰,为70～100 Hz.而明适应不同刺激光强度下,SD大鼠和CSNB大鼠均只有一个频峰,分别为75～95 Hz和70～85 Hz.明适应条件下与SD大鼠比较,CSNB大鼠b波隐含时延长,b波振幅明显下降,差异均有统计学意义(P＜0.05);暗适应条件下,RCD大鼠b波隐含时和振幅与SD大鼠比较,差异无统计学意义(P＞0.05);与SD大鼠比较,RCD和CSNB大鼠OPs波振幅下降,隐含时延长,差异均有统计学意义(P＜0.05);明适应条件下不同刺激光强度下CSNB大鼠OPs波的隐含时明显长于SD大鼠,振幅明显低于SD大鼠,差异均有统计学意义(P＜0.05). 结论 视锥、视杆通路起源的OPs有不同特性,自发性视网膜退行性改变大鼠的视杆OPs有两个频峰,正常情况下,视杆通路对OPs的贡献比视锥通路大.     

腹腔注射MNU对大鼠视网膜结构与功能的影响

目的　探讨N 甲基 N 亚硝脲 (N methyl N nitrosourea,MNU)对大鼠视网膜的毒性作用。方法　生后 5 0d的雌性SD鼠 76只 ,随机抽取 4只为正常对照组 ,余 72只等分为 3组 ,分别按体重一次性腹腔注射MNU 5 0、4 0、30mg·kg-1。各组每次 4只分别于6、12、2 4、4 8h ,3、5d行闪光视网膜电图 (ERG)检查 ,并于造模 1、2、3、5、7、10d全麻后处死动物 ,取眼球做病理切片。结果　MNU 5 0、4 0、30mg·kg-1剂量组ERGa波消失时间分别为 6、12h ,3d ,b波消失时间分别是 12、2 4h ,5d。HE染色显示 :以中周部视网膜为观察对象 ,MNU 30mg·kg-1组第 3天开始出现外颗粒层结构改变 ,第 10天光感受器细胞显著减少 ,但未消失 ;MNU 4 0和 5 0mg·kg-1组第 1天即出现外颗粒层排列紊乱 ,外颗粒层消失时间前者在第 10天 ,后者在第 5天。所有模型切片结果 ,其神经节细胞层、内颗粒层以及色素上皮层与正常组相比均未见明显差异。结论　MNU能选择性地损伤视网膜光感受器细胞。     

Microarray-based gene expression analysis during retinal maturation of albino rats

Background In recent years, the rat has become a commonly-used animal model for the study of retinal diseases. Similar to other tissues, the retina undergoes significant functional changes during maturation. Aiming to gain knowledge on additional aspects of retinal maturation, we performed gene expression and histological analyses of the rat retina during maturation. Methods Rat retinas were dissected at three time points. Histological examination of the samples was performed, and the expression levels of retinal genes were evaluated using the rat whole-genome microarray system. Quantitative real-time PCR analysis was used to validate selected expression patterns. Various statistical and bioinformatic tools were used to identify differentially expressed genes. Results The microarray analysis revealed a relatively high number of highly expressed non–annotated genes. We identified 603 differentially expressed genes, which were grouped into six clusters based on changes in expression levels during the first 20 weeks of life. A bioinformatic analysis of these clusters revealed sets of genes encoding proteins with functions that are likely to be relevant to retinal maturation (potassium, sodium, calcium, and chloride channels, synaptic vesicle transport, and axonogenesis). The histological analysis revealed a significant reduction of outer nuclear layer thickness and retinal ganglion cell number during maturation. Conclusions These data, taken together with our previously reported electrophysiological data, contribute to our understanding of the retinal maturation processes of this widely-used animal model. Supported by: The Joseph Alexander Foundation and the Alberto Moscona Foundation.     

大鼠视网膜变性中药保护作用的实验研究

目的观察金钠多(Ginaton,Gin)和葛根素(Puerarin,Pue)对N-甲基-N-亚硝脲(N-methyl-N-nitrosorea,MNU)诱导SD大鼠视网膜变性的保护作用及机制。方法雌性SD大鼠随机分为正常对照组、模型组、Gin大剂量和中剂量组、Pue大剂量和中剂量组。于生后47d开始腹腔注射给药,每日1次。并于生后50d,模型组和各药物处理组的大鼠腹腔注射MNU60mg·kg-1,正常对照组腹腔注射生理盐水。在MNU或生理盐水处理后不同时间处死动物,取眼球。视网膜形态学分析测量周边视网膜总厚度,TUNEL试剂盒检测感受器细胞凋亡。结果MNU处理7d后,模型纽周边视网膜总厚度为36μm,Gin组(大剂量和中剂量)和Pue组(大剂量和中剂量)分别为(44±2)μm,(37±2)μm,(46±2)μm,(35±2)μm。MNU处理24h后,模型组周边视网膜光感受细胞凋亡指数为(38.0±3.6)%,Gin大剂量组、中剂量组、Pue大剂量组和中剂量组分别为(26.3±2.7)%,(37.4±2.9)%,(25.4±3.0)%,(39.0±2.5)%.结论Gin和Pue对MNU引起周边视网膜损伤有一定的保护作用,呈剂量依赖性,其作用机制是通过抑制光感受器细胞发生凋亡。但二者对中心视网膜均无保护作用。