灯盏细辛对兔高眼压视网膜神经节细胞活性的作用

目的观察灯盏细辛对慢性高眼压兔视网膜神经节细胞活性的保护作用。方法对20只健康新西兰白兔右眼前房内注射40g·L-1甲基纤维素,制成慢性高眼压模型,左眼眼压均正常,随机分成灯盏细辛治疗组(n=10,高眼压+灯盏细辛治疗亚组和正常眼压+灯盏细辛治疗亚组)和未治疗组(n=10,单纯高眼压亚组和单纯正常眼压亚组)。治疗组于高眼压模型制作后第7d开始行灯盏细辛悬浊液灌胃,60d后制作眼球标本。常规石蜡切片,AgNOR染色观察RGCs细胞核内的银染颗粒。采用计算机图像分析系统对RGCs细胞核内的银染颗粒进行定量分析。结果高眼压2亚组较正常眼压2亚组的RGCs细胞核内银染颗粒明显减少,其差异有显著性意义(P<0.05);其中高眼压+灯盏细辛治疗亚组较单纯高眼压亚组银染颗粒多(P<0.05)。结论40g·L-1甲基纤维素前房注射建立慢性高眼压模型可导致RGCs细胞核内银染颗粒减少,灯盏细辛对高眼压后RGCs活性有一定的保护作用。     

αB-晶状体蛋白对急性高眼压大鼠视网膜神经节细胞保护作用机制的研究

目的　研究αＢ-晶状体蛋白对钾离子通道ｋｖ１．１、ｋｖ１．３及凋亡抑制因子Ｂｃｌ-ｘｌ和凋亡因子Ｃａｓｐａｓｅ-３的影响,探讨αＢ-晶状体蛋白对急性高眼压大鼠视网膜神经节细胞（ｒｅｔｉｎａｌｇａｎｇｌｉｏｎｃｅｌｌｓ,ＲＧＣ）保护作用的机制。方法　６０只ＳＤ大鼠随机分为Ａ组（急性高眼压组）、Ｂ组（急性高眼压＋玻璃体内注射生理盐水５μＬ组）、Ｃ组（急性高眼压＋玻璃体内注射１０×１０－６ｇ?Ｌ－１αＢ-晶状体蛋白５μＬ组）,每组２０只,右眼为实验眼。注射后７ｄ和１４ｄ时,应用Ｗｅｓｔｅｒｎｂｌｏｔ和实时定量逆转录聚合酶链反应（ＱＲＴ-ＰＣＲ）法检测ｋｖ１．１、ｋｖ１．３、Ｂｃｌ-ｘｌ和Ｃａｓｐａｓｅ-３在视网膜上的表达水平。结果　注射后７ｄ和１４ｄ时,Ｃ组ｋｖ１．１、ｋｖ１．３通道蛋白和凋亡因子Ｃａｓｐａｓｅ-３蛋白表达水平和ｍＲＮＡ相对表达量均较Ａ组、Ｂ组低,差异均有统计学意义（均为Ｐ＜０.０５）;Ｃ组Ｂｃｌ-ｘｌ蛋白表达水平和ｍＲＮＡ相对表达量较Ａ组、Ｂ组高,差异均有统计学意义（均为Ｐ＜０．０５）;相同时间点不同因子Ａ组、Ｂ组间两两比较,差异均无统计学意义（均为Ｐ＞０．０５）。结论　αＢ-晶状体蛋白通过抑制急性高眼压后ＲＧＣ上钾离子通道ｋｖ１．１、ｋｖ１．３的表达,从而提高凋亡抑制因子Ｂｃｌ-ｘｌ的表达、降低凋亡因子Ｃａｓｐａｓｅ-３的表达,减少细胞凋亡,保护ＲＧＣ。     

银杏叶提取物联合灯盏细辛对视网膜神经节细胞的保护作用

目的:探讨银杏叶提取物联合灯盏细辛对兔慢性高眼压模型视网膜神经节细胞的保护作用。方法:采用α-糜蛋白酶(0.2mL)(2667.2μkat)注入家兔眼后房,造成实验性慢性高眼压。将造模成功的32只家兔随机分为4组,每组8只,分别给予以下治疗:银杏叶提取物150mg/kg(银杏叶组);灯盏细辛150mg/kg(灯盏细辛组);银杏叶提取物联合灯盏细辛皆灌胃,1次/d银杏叶提取加灯盏细辛(联合用药组);不做任何治疗(模型对照组)。4wk后各组分别进行视网膜神经节细胞凋亡检测正常视神经节细胞计数和光镜观察视网膜各层病理改变。结果:每组均可观察到阳性细胞,正常神经节细胞计数最多为联合用药组(889.00±40/mm2)、最少为模型对照组(581±24/mm2),P<0.01,光镜下模型对照组视网膜各层结构最紊乱,联合用药组视网膜各层组织最完整。结论:银杏叶提取物联合灯盏细辛能阻止高眼压导致视网膜神经节细胞发生凋亡。     

藏红花素与灯盏细辛对慢性高眼压模型大鼠视神经保护作用的比较

背景 青光眼视神经损害的主要机制是视觉神经元的凋亡和视网膜血液供应的减少,灯盏细辛已证实对高眼压大鼠视网膜神经节细胞(RGCs)和视神经有保护作用.研究发现,藏红花提取物具有抗炎、抑制神经元凋亡和调节血流等作用,但其能否保护青光眼患者的RGCs尚不清楚. 目的 探讨藏红花素对慢性高眼压模型大鼠视神经的保护作用.方法 采用随机数字表法将32只SD大鼠随机分为假手术组、模型对照组、灯盏细辛组、藏红花素组,每组8只,均以右眼为实验眼.模型对照组、灯盏细辛组、藏红花素组大鼠采用巩膜静脉烧灼法建立慢性高眼压模型;假手术组大鼠仅剪开结膜,灯盏细辛组和藏红花素组大鼠于术前30 rmin和术后每日分别腹腔内注射灯盏细辛注射液150 mg/kg(0.5 ml)和藏红花素20 mg/kg(0.5 ml),共给药4周,假手术组和模型对照组大鼠以同样的方式注射0.5 ml生理盐水.各组大鼠均于术前和术后1d、3d、1周、2周、3周、4周测量眼压.术后4周制备大鼠眼球及视神经标本,采用苏木精-伊红染色法测定视网膜厚度;采用TUNEL染色法计数RGCs凋亡数量;采用透射电子显微镜观察各组大鼠视神经轴突超微结构的变化;采用Western blot法检测视网膜中bcl-2和bax蛋白的表达.结果 模型对照组、灯盏细辛组和藏红花素组大鼠造模和干预后不同时间点眼压均明显高于假手术组,造模后不同时间点大鼠的眼压值均明显高于造模前,各组大鼠在造模前后不同时间点眼压值的变化差异均有统计学意义(F分组=169.079,P=0.000;F时间=50.505,P=0.000).假手术组、模型对照组、灯盏细辛组和藏红花素组大鼠视网膜厚度分别为(192.72±4.28)、(165.15±3.89)、(177.75±3.35)和(182.48±4.12) μm,藏红花素组大鼠视网膜厚度值明显低于假手术组而高于模型对照组和灯盏细辛组,差异均有统计学意义(均P＜0.05).假手术组、模型对照组、灯盏细辛组和藏红花素组大鼠RGCs凋亡率分别为(2.58±1.33)％、(42.10±4.71)％、(28.34±2.96)％和(19.95±2.93)％,藏红花素组大鼠RGCs凋亡率明显低于模型对照组和灯盏细辛组,差异均有统计学意义(均P＜0.05).藏红花素组大鼠视神经有髓纤维数量和bcl-2/bax值均明显高于模型对照组和灯盏细辛组,差异均有统计学意义(均P＜0.05).结论 藏红花素可抑制RGCs凋亡和视神经纤维的变性,对慢性高眼压大鼠视网膜神经细胞发挥保护作用,其对视神经的保护作用强于灯盏细辛.     

超声微泡造影剂联合鼠神经生长因子对高眼压兔视神经损害的保护作用

目的　观察超声微泡造影剂联合鼠神经生长因子（ｍｏｕｓｅｎｅｒｖｅｇｒｏｗｔｈｆａｃｔｏｒ,ｍＮＧＦ）对高眼压兔视神经损害的保护作用。方法　新西兰大白兔４０只,随机分为５组（每组８只）。空白对照组（Ａ组）、高眼压模型组（Ｂ组）、高眼压模型＋玻璃体内注射ｍＮＧＦ组（Ｃ组）、高眼压模型＋玻璃体内注射ｍＮＧＦ联合超声组（Ｄ组）、高眼压模型＋玻璃体内注射ｍＮＧＦ联合超声微泡组（Ｅ组）。行闪光视觉诱发电位（ｆｌａｓｈｖｉｓｕａｌｅｖｏｋｅｄｐｏｔｅｎｔｉａｌ,Ｆ-ＶＥＰ）检测,记录Ｐ１００波潜伏期及振幅;取各组兔视网膜行病理形态学观察和透射电镜观察兔视神经超微结构。结果　Ｂ组眼压在造模后１周、２周、４周分别为（３３．４±２．８）ｍｍＨｇ（１ｋＰａ＝７．５ｍｍＨｇ）、（３４．１±２．５）ｍｍＨｇ和（３４．８±２．２）ｍｍＨｇ,与Ａ组眼压（１３．６±１．８）ｍｍＨｇ、（１３．４±１．７）ｍｍＨｇ和（１３．３±１．４）ｍｍＨｇ相比差异有显著统计学意义（Ｐ＝０．０００）。Ｂ组的Ｐ１００潜伏期（１２５．００±１８．７０）ｍｓ和振幅（５．５０±３．０３）ｎＶ较Ａ组的Ｐ１００潜伏期（４６．２０±６．９０）ｍｓ和振幅（１５．９０±２．４８）ｎＶ明显延长和降低,差异有统计学意义（Ｐ＜０．０５）;Ｅ组的Ｐ１００潜伏期（６３．８０±８．３５）ｍｓ和振幅（１１．３７±２．８４）ｎＶ较Ｂ、Ｃ、Ｄ组明显缩短和升高,差异有统计学意义（Ｐ＜０．０５）。Ｂ组视网膜神经节细胞（ｒｅｔｉｎａｌｇａｎｇｌｉｏｎｃｅｌｌｓ,ＲＧＣ）计数（１４．９７±１．３０）个明显少于Ａ组（２６．０４±０．７０）个,差异有统计学意义（Ｐ＜０．０５）;Ｅ组ＲＧＣ计数（２３．９７±０．９０）个明显高于Ｂ、Ｃ、Ｄ组,但仍低于Ａ组,差异有统计学意义（Ｐ＜０．０５）。Ｅ组兔视网膜各层结构较Ｂ、Ｃ、Ｄ组完整,分层较清晰。Ｅ组兔视神经髓鞘结构尚完整,轴突内微管、微丝结构可见,较Ｂ、Ｃ、Ｄ组视神经超微结构明显改善。结论　超声微泡造影剂与鼠神经生长因子联合使用可增强鼠神经生长因子对高眼压兔视神经损害的保护作用。     

急性高眼压状态大鼠虹膜睫状体一氧化氮及其合酶的变化

目的：通过对急性高眼压大鼠虹膜睫状体一氧化氮及其合酶变化的分析，探讨一氧化氮在青光眼发病机理中可能的作用。方法：Ｗｉｓｔｅｒ大鼠２４只，随机分为高眼压３０分钟组；高眼压６０分钟组；高眼压９０分钟组；前房加压灌主制成高眼压模型。得用镀铜镉还原法测定虹膜中ＮＯ２＾－／ＮＯ３＾－的含量从而间接反映虹膜组织中ＮＯ的含量。利用免疫组织化学法研究睫状体内内皮结构型一氧化氮梧酶（ｅｃＮＯＳ）的分布及其变化。结果     

急性闭角型青光眼急性发作期持续性高眼压的手术探讨

目的：通过周过虹膜切膜切除术与小梁切除术的对比研究,探讨周边虹膜切除术治疗治急性闭角型青光眼（以下简称急闭）急性发作期持续性高眼压的有效性和安全性,方法：６３例（６３只眼）经最大剂量降眼压药物紧急处理后眼压仍〉４００ｍｍＨｇ的急闭急性发作期患者,随机分成周迦虹膜切除术组（以下简称周切组）（３３只眼）和小梁切除术组（以下简称小梁组（３０只眼）。结果：术后随访６～６６个月,平均２１．５个月。周切组手术     

银杏叶提取物对急性缺血再灌注后视网膜神经节细胞的保护作用

目的探讨银杏叶提取物（EGb761）对大鼠急性高眼压诱导缺血再灌注模型中视网膜神经节细胞（RGCs）的保护作用。方法60只SD大鼠随机分为5组,右眼为损伤眼,行前房穿刺灌注形成110mmHg的眼压维持60min,左眼未损伤,作为空白对照。损伤后2h及此后每日1次灌胃给药,各组分别给予生理盐水5mg／kg、1％灯盏细辛5mg／kg、0．25％EGb761 5mg／kg、1％EGb7615mg／kg和4％EGb761 5mg／kg。动物损伤后第23天用荧光金行双上丘逆行标记,第28天取眼球标本做视网膜铺片并拍摄照片,计数RGCs并计算其的存活率。结果生理盐水组、1％灯盏细辛组、0．25％EGb761、1％EGb761和4％EGb761组RGCs存活率分别为66．58％、75．62％、74．92％、76．57％、79．87％。生理盐水组与各EGb761组之间差异均有统计学意义（q=0．00,q=0．19,q=0．10,P〈0．01）,不同质量浓度EGb761组之间差异均无统计学意义（q=0．22,q=0．13,q=0．45,P〉0．05）;1％灯盏细辛组与生理盐水对照组比较差异有统计学意义（q=0．16,P=0．02）,与0．25％EGb761组、1％EGb761组、4％EGb761组比较差异均无统计学意义（q=0．20,q=0．01,q=0．50,P〉0．05）。结论在急性高眼压诱导缺血再灌注模型中,银杏叶提取物能有效地保护RGCs。     

表皮生长因子受体抑制剂抑制大胶质细胞活化对急性高眼压大鼠视网膜神经节细胞丢失的研究

目的　探讨表皮生长因子受体（ｅｐｉｄｅｒｍａｌｇｒｏｗｔｈｆａｃｔｏｒｒｅｃｅｐｔｏｒ,ＥＧＦＲ）抑制剂抑制大胶质细胞活化对实验性急性高眼压大鼠视网膜神经节细胞（ｒｅｔｉｎａｌｇａｎｇｌｉｏｎｃｅｌｌｓ, ＲＧＣｓ）丢失的影响。方法　用健康成年ＳＤ大鼠１８只,随机分为３组:空白对照组,不做任何处理;实验组采用前房灌注法制造急性高眼压模型,造模成功后,按６ｍｇ?ｋｇ－１?ｄ－１用量给予大鼠口服ＥＧＦＲ抑制剂ＡＧ１４７８;实验对照组造模成功后给予大鼠口服等量生理盐水。３组均于７ｄ处死大鼠,观察各组视网膜结构的变化及采用免疫组织化学法观察阳性节细胞的表达。结果　通过免疫组化法发现,随着造模时间的延长,视网膜结构变得模糊不清,ＲＧＣｓ阳性染色细胞逐渐减少。空白对照组、实验组、实验对照组ＲＧＣｓＴｈｙ-１阳性表达光密度值分别是:１４３．６６６７±４．０４１５、１３９．０３２２±１．７３４０和１０１．１０２３±２．０００１。实验组和空白对照组相比,视网膜Ｔｈｙ-１阳性表达差异无统计学意义（Ｐ＞０．０５）,实验对照组和空白对照组比较,差异有统计学意义（Ｐ＜０．０５）,实验组与实验对照组视网膜Ｔｈｙ-１阳性表达,差异亦有统计学意义（Ｐ＜０．０５）。结论　ＥＧＦＲ抑制剂通过抑制大胶质细胞的活化对实验性急性高眼压大鼠模型的ＲＧＣｓ有保护作用。     

外源性SOD对兔急性高眼压致视网膜损伤保护作用的研究

目的探讨高眼压后活性氧自由基对视网膜组织的损伤情况及外源性超氧化物歧化酶（ｓｕｐｅｒｏｘｉｄｅｄｉｓｍｕｔａｓｅ,ＳＯＤ）对高眼压致视网膜损伤的保护作用。方法观察６．６７ｋＰａ（１ｋＰａ＝７．５ｍｍＨｇ）、维持１．５ｈ的高眼压解除２４ｈ内兔视网膜组织中脂质过氧化产物丙二醛（ｍａｌｏｎｄｉａｌｄｅｈｙｄｅ,ＭＤＡ）含量、ＳＯＤ活性、谷胱甘肽过氧化物酶（ｇｌｕｔａｔｈｉｏｎｅｐｅｒｏｘｉｄａｓｅ,ＧＳＨ－Ｐｘ）活性和还原型谷胱甘肽（ＧＳＨ）含量的变化情况及球后注射Ｃｕ－Ｚｎ－ＳＯＤ对高眼压解除后１２ｈ时兔视网膜组织中ＭＤＡ含量和ＳＯＤ活性的影响。结果ＭＤＡ在高眼压解除后０～１２ｈ逐渐增加,１２～２４ｈ维持较高水平。ＳＯＤ活性和ＧＳＨ－Ｐｘ活性在高眼压解除即刻均低于正常水平,以后有不同程度增高,其中ＳＯＤ活性在高眼压解除４ｈ后又开始下降。ＧＳＨ在高眼压解除后２４ｈ内无明显变化。球后注射Ｃｕ－Ｚｎ－ＳＯＤ能减少兔视网膜组织中ＭＤＡ生成,增加ＳＯＤ活性。结论活性氧自由基参与了高眼压致视网膜损伤,球后注射大剂量ＳＯＤ对提高视网膜抗氧化损伤能力有积极意义。     

灯盏细辛对大鼠视神经压榨伤后视网膜神经节细胞的保护作用

目的　探讨中草药灯盏细辛对大鼠标定性视神经压榨伤所致的视网膜神经节细胞(RGC)损伤的防护和修复作用。方法　 4 2只健康SD大鼠随机均分为A组和B组。两组均用特制微型视神经夹直接夹持视神经 ,制作成单眼视神经部分压榨伤模型后 ,A组不予任何治疗 ,B组予以灯盏细辛治疗 ,直至处死动物。以上两组按致伤日至处死日动物的存活时间又分为 :A1组和B1组 (损伤后 4d) ,A2 组和B2 组 (损伤后 14d) ,A3 组和B3 组 (损伤后 2 1d) ,每组各 7只大鼠。于处死前 3d双上丘直接注射 3%快蓝标记双眼RGC。处死日行眼球摘除术后 ,将双眼全视网膜组织铺片置于荧光显微镜下 ,在距视乳头 1mm处的颞上、颞下、鼻下及鼻上 4处作荧光摄影 ,并输入计算机经图像分析仪计数RGC。计算RGC标识率 ,即 (损伤眼RGC数 /未损伤眼RGC数 )× 10 0 % ,并进行统计学分析。结果　A组大鼠中 ,A1、A2 及A3 组的RGC标识率分别为 (77 79± 7 11) %、(6 3 76± 3 79) %、(5 4 6 6±4 75 ) % ;B组大鼠中 ,B1、B2 及B3 组的RGC标识率分别为 (80 13± 12 0 3) %、(78 17± 9 19) %及(83 5 9± 12 6 1) %。A2 和A3 组分别与B2 和B3 组比较 ,差异均有非常显著意义 (t=14 10 8,36 2 0 3;P<0 0 1)。结论　大鼠标定性视神经压榨伤后用灯盏细辛治疗 ,     

Induction of heat shock protein 72 protects retinal ganglion cells in a rat glaucoma model

PURPOSE: To investigate whether heat shock protein (Hsp) 72 is induced in retinal ganglion cells (RGCs) in experimental rat glaucoma and whether the induction of Hsp72 by heat stress or zinc (Zn(2+)) administration can increase survival of RGCs in the model. METHODS: Intraocular pressure (IOP) was elevated unilaterally in Wistar rats with argon laser irradiation of the trabecular meshwork 5 days after intracameral injection of india ink. Immunohistochemical staining for Hsp72 was performed. The rats with elevated IOP were treated with heat stress once a week (six rats) or intraperitoneal injection of zinc (10 mg/kg) every two weeks (six rats). Untreated rats with elevated IOP served as a control group (six rats). Quercetin, an inhibitor of Hsp expression was injected in the rats with heat stress (six rats) and zinc injection (seven rats). Subsequent to 4 weeks of IOP elevation, RGCs were counted. RESULTS: The IOP increase compared with the contralateral eyes was 48% +/- 4% throughout the study period. Hsp72 was detected only in the eyes with elevated IOP at 1 and 2 days and was weakly detected at 1 week of IOP elevation. A single administration of zinc strongly induced Hsp72 in RGCs of rats with elevated IOP for 2 weeks. Treatment with heat stress or zinc in rats with elevated IOP increased RGC survival after 4 weeks of IOP elevation, compared with the untreated control group (P = 0.004, n = 6). Quercetin reversed the positive effect of heat stress or zinc injection on RGC survival. CONCLUSIONS: These results demonstrate the possibility of a novel therapeutic approach to glaucoma through an enhanced induction of the endogenous heat shock response.     

Retinal ganglion cell protection with geranylgeranylacetone,a heat shock protein inducer,in a rat glaucoma model

PURPOSE: To study the effects of geranylgeranylacetone (GGA) on the expression of inducible (HSP72) and constitutive (HSC70) heat shock proteins (HSPs) on retinal ganglion cells (RGCs) in a rat model of glaucoma. METHODS: Adult Wistar rats were given intraperitoneal injections of GGA at 200 mg/kg daily. Western blot analysis and immunohistochemical staining for HSP72 and HSC70 were performed after 1, 3, and 7 days of treatment with GGA. After 7 days of GGA pretreatment, intraocular pressure (IOP) was elevated unilaterally by repeated trabecular argon laser photocoagulation 5 days after intracameral injection of india ink. After the first laser photocoagulation, GGA was administered twice a week. RGC survival was evaluated after 5 weeks of elevated IOP. Immunohistochemistry and TdT-mediated biotin-dUTP nick end labeling (TUNEL) were performed after 1 week of elevated IOP. Quercetin, an inhibitor of HSP expression, was also administered to a separate group. RESULTS: There was increased expression of HSP72 in RGCs at 3 and 7 days after administration of GGA, but HSC70 was unchanged. After 5 weeks of elevated IOP, there was a 27% +/- 6% loss of RGCs. The administration of GGA significantly reduced the loss of RGCs, lessened optic nerve damage, decreased the number of TUNEL-positive cells in the RGC layer, and increased HSP72. Quercetin abolished these protective effects. CONCLUSIONS: These results demonstrate that systemic administration of GGA protects RGCs from glaucomatous damage in a rat model and suggest a novel pathway for neuroprotection in patients with glaucoma.     

Heat Shock Protein 72 Protects Retinal Ganglion Cells in Rat Model of Acute Glaucoma

Purpose: To investigate whether the induction of heat shock protein (HSP)72 by heat stress (HS) or zinc (Zn2 ) administration can increase survival of retinal ganglion cells (RGC)in rat model of acute experimental glaucoma. Methods: Acute glaucoma model was made by intracameral irrigation with BSS at 102 mmHg for two hours in right eyes of male Wistar rats. Glaucoma model rats were treated with HS once a week (six rats) or intraperitoneal injection of zinc sulfate (24.6 mg/kg) every two weeks (six rats), and were referred to as HS group and zinc group, respectively. Untreated model rats served as damage group (six rats). In control groups, querc-etin (400 mg/kg) was intraperitoneally injected to inhibit the induction of heat shock proteins 6 hours before HS or zinc administration, and were referred to as HS que group (six rats) and zinc que group (six rats), respectively. Subsequent to 16 days of IOP elevation, the rats were sacrificed. Eyes were quickly enucleated, and the retinas were dissected. RGC were labeled with Nissl staining and counted under microscope. Results: The average RGC density in normal Wistar rats was (2504±181) cells/mm2. In damage group, it decreased to (2015±111) cells/mm2. The RGC densities at 1,2, and 3 mm from the center of the optic nerve head were (2716±215), (2496±168), and (2317±171) cells/mm2, respectively, for normal rats and (2211±133), (1969±154), and (1872±68) cells/mm2, respectively, for damage group. The latter was significantly lower at all locations compared with the former (P=0.027 for each, Mann-Whitney test). The average RGC densities were (2207±200) cells/mm2 for HS group, (2272±155) cells/mm2 for zinc group, (1964±188) cells/mm2 for HS que group, (2051 ±214) cells/mm2 for zinc que group and (2015±111) cells/mm2for damage group. There were significant differences in density of labeled RGCs among the five groups (P=0.040, Kruskal-Wallis test). Both HS and zinc group had higher RGC densities than damage group (P =0.036 between HS and damage group,P=0.019 between zinc and damage group,Mann-Whitney test). There was no significant difference in RGC densitiy between control groups and damage group (P=0.260 between HS que and damage group,P=0.748 between zinc que and damage group, Mann-Whitney test). Conclusions: The results demonstrated that the induction of HSP72 in RGCs by HS or zinc administration plays an important role in the survival of RGCs in rat model of acute glaucoma. A novel therapeutic approach to glaucoma through an enhanced induction of endogenous HSP72 could be possible. Eye Science 2005;21:163-168.     

Dorzolamide and timolol saves retinal ganglion cells in glaucomatous adult rats.

PURPOSE: This study was designed to evaluate the effects of a dorzolamide-timolol combination or dorzolamide on retinal ganglion cell (RGC) density and intraocular pressure (IOP) in glaucomatous eyes of adult rats. METHODS: Glaucoma was induced in the right eye of adult Wistar rats by episcleral venous occlusion. One experimental group was administered dorzolamide 2%-timolol 0.5% combination eye drops, while the other experimental group was administered dorzolamide 2% eye drops. Control groups had surgery without drug administration. Drug application was initiated either 2 weeks before surgery (Group A), from the day of surgery (Group B), 2 weeks after surgery (Group C), or 4 weeks after surgery (Group D). RGCs were labeled by intratectal Fluorogold injections and counted from flat-mount preparations, and IOP was measured using Tonopen. RESULTS: Both dorzolamide-timolol combination and dorzolamide, when applied topically, significantly reduced IOP and improved RGC densities in experimental eyes when compared to control eyes. Earlier initiation, as well as longer duration of drug application, resulted in higher RGC densities. CONCLUSIONS: Topical application of a dorzolamide-timolol combination or dorzolamide saved RGCs to a significant extent and reduced IOP in glaucomatous rat eyes.     

Different responses of macrophages in retinal ganglion cell survival after acute ocular hypertension in rats with different autoimmune backgrounds

Recently macrophages were shown to play a protective role in retinal ganglion cells (RGCs) after optic nerve (ON) injury. In the present study, we investigated how macrophages responded after acute intraocular pressure (IOP) elevation in experimental autoimmune encephalomyelitis (EAE)-resistant Fischer 344 (F344) and Sprague Dawley (SD) rats and EAE-vulnerable Lewis rats. Acute IOP elevation was performed at 110mmHg for 2h to mimic acute glaucoma. Phagocytic cells in the eye were removed by intravitreal application of clodronate liposomes whereas macrophage activation was achieved by intravitreal injection of zymosan, a yeast wall preparation. Fluorescence dye, FluoroGold, was applied behind the eyeballs to retrogradely label surviving RGCs 40h before animal sacrifice. Macrophages in the retina were identified by ED1 immunostaining. Loss of 25% RGCs in F344 but over 90% in Lewis rats was seen 2 weeks after acute IOP elevation. Significant increase in the number of macrophages in the retina was seen to accompany the great RGC loss in Lewis rats; removal of these macrophages reduced the extent of RGC loss, suggesting the involvement of macrophages in RGC death in Lewis strain. Low numbers of macrophages were seen in F344 retinas after acute IOP elevation, and removal of macrophages did not show clear effect on RGC viability. Whereas macrophage activation by zymosan protected RGCs after ON axotomy in F344 rats, the same macrophage activation became detrimental to RGCs after acute IOP elevation. The extent of RGC loss 3 weeks after acute IOP elevation or after macrophage activation by zymosan in EAE-resistant SD rats was similar to that in F344 rats. We thus demonstrate that macrophages in rats with different autoimmune backgrounds react differently to acute IOP elevation and differentially modulate RGC loss, a phenomenon contrary to the protective action in RGCs after ON axotomy. These data suggest that autoimmune background plays a role in modulating vulnerability of RGCs to acute IOP elevation.     

Retrograde axonal transport of BDNF in retinal ganglion cells is blocked by acute IOP elevation in rats

PURPOSE: To determine whether acute experimental glaucoma in rats obstructs retrograde transport of brain-derived neurotrophic factor (BDNF) to retinal ganglion cells (RGCs). METHODS: Forty rats had unilateral injection of either (125)I-BDNF (20 animals) or a mixture of (125)I-BDNF and 100-fold excess nonradiolabeled BDNF (20 animals). In each group of 20 animals, eyes contralateral to injection had either normal intraocular pressure (IOP; 10 animals) or IOP elevated to 25 mm Hg below the systolic blood pressure of the eye (10 animals). In each group of 20 rats, ipsilateral eyes had IOP set at systolic blood pressure (4 eyes), had optic nerve transection (10 eyes), or had normal IOP (6 eyes). Six hours after injection, animals were killed and tissues were fixed, embedded, and sectioned for autoradiography. Grain counts were performed over retina and optic nerve using automated image analysis. RESULTS: IOP elevation to 25 mm Hg below systolic blood pressure (perfusion pressure [PP] 25) decreased median retinal nerve fiber layer (NFL) grains by 38% compared with controls (P: < 0.001). Competition by cold BDNF reduced NFL grains by 28% (P: = 0.013). Considering only the radioactivity representing specific retrograde transport of BDNF, IOP elevation to PP25 reduced transport by 74%, whereas elevation to PP0 (equaling systolic blood pressure) reduced specific transport by 83%. CONCLUSIONS: BDNF is transported retrogradely from the superior colliculus in adult rats, and this transport is substantially inhibited by acute IOP elevation. Deprivation of BDNF among RGCs may contribute to neuron loss in glaucoma.     

Obstructed axonal transport of BDNF and its receptor TrkB in experimental glaucoma

PURPOSE: In both animal model system and in human glaucoma, retinal ganglion cells (RGCs) die by apoptosis. To understand how RGC apoptosis is initiated in these systems, the authors studied RGC neurotrophin transport in experimental glaucoma using acute intraocular pressure (IOP) elevations in rats and chronic IOP elevation and unilateral optic nerve transections in monkeys. METHODS: Eyes were studied in masked fashion by light and electron microscopy and by immunohistochemistry with antibodies directed against the tyrosine kinase receptors (TrkA, B, and C) and against brain-derived neurotrophic factor (BDNF), as well as by autoradiography to identify retrograde axonal transport of 125I-BDNF injected into the superior colliculus. RESULTS: With acute glaucoma in the rat, RGC axons became abnormally dilated, accumulating vesicles presumed to be moving in axonal transport at the optic nerve head. Label for TrkB, but not TrkA, was relatively increased at and behind the optic nerve head with IOP elevation. Abnormal, focal labeling for TrkB and BDNF was identified in axons of monkey optic nerve heads with chronic glaucoma. With acute IOP elevation in rats, radiolabeled BDNF arrived at cells in the RGC layer at less than half the level of control eyes. CONCLUSIONS: Interruption of BDNF retrograde transport and accumulation of TrkB at the optic nerve head in acute and chronic glaucoma models suggest a role for neurotrophin deprivation in the pathogenesis of RGC death in glaucoma.     

A rat model for acute rise in intraocular pressure: immune modulation as a therapeutic strategy

PURPOSE: To establish a rat model of acute increase in intraocular pressure (IOP) and to investigate the therapeutic window for protection against death of retinal ganglion cells (RGCs) by vaccination with glatiramer acetate (Cop-1) or by treatment with brimonidine or MK-801. DESIGN: Animal study, laboratory investigation. METHODS: IOP was transiently increased in anesthetized Lewis rats by infusing normal saline (0.9%) into the anterior chamber of the eye for one hour. RGC survival was assessed one week and two weeks later by counting the RGCs retrogradely labeled with rhodamine dextran. MAIN OUTCOME MEASURES: RGC survival. RESULTS: IOP rose to 100 cm H(2)O (76 mm Hg) and returned to baseline after 24 hours. The RGC count decreased by 23% a week after the insult and by a further 7% after the second week. Vaccination with Cop-1 on the day of the insult prevented 50% of the IOP-induced RGC loss. Similar neuroprotection was achieved by daily intraperitoneal injections of brimonidine, but not with MK-801. CONCLUSIONS: A transient increase in IOP to 100 cm H(2)O causes death of RGCs in rats. A single immunization with Cop-1 or daily injections of brimonidine protected up to 50% of potentially doomed RGCs from IOP-induced death, suggesting that not all of the cell death in the untreated model results from the IOP insult directly, but that some of it is caused by insult-induced environmental cytotoxicity, which is unrelated to glutamate toxicity or at least to NMDA receptors. These findings can be applied immediately as a basis for acute glaucoma therapy.     

Retinal damage after 3 to 4 months of elevated intraocular pressure in a rat glaucoma model

PURPOSE: To characterize a long-term elevated intraocular pressure (IOP) glaucoma model in the rat with respect to electroretinographic (ERG) changes and the pattern and mechanism of retinal ganglion cell (RGC) death. METHODS; An approximate doubling of IOP was induced in one eye (G) of female Wistar rats (150-180 g) by cautery of 3 episcleral/limbal veins. At intervals over 3 to 4 months, measurements of IOP and ERG changes (contact-lens electrode) were made in both the G and contralateral normal (N) eyes. At the end of 3 to 4 months of elevated IOP, RGCs were fluorescently labeled with Fluorogold (retrogradely from the superior colliculus), or retinas were labeled by intravitreal injection of a mitochondrial potential indicator dye and stained for apoptotic nuclei with a DNA dye. Flatmounts of fixed, dye-labeled retinas were examined by epifluorescence, confocal, or interference contrast microscopy. RESULTS: Elevated IOP was consistently maintained for up to 4 months in G eyes, but ERG a- and b-waves showed a statistically significant decline, of 30% to 40% in amplitude, after 3 months. Loss of RGCs in G retinas was primarily focal with no statistically significant loss demonstrable outside of the focal areas when assessed by an area sampling method for counting RGCs, which totaled 2% to 3% of the entire retinal area. Mitochondrial membrane potential of cells in the RGC layer was reduced by 17.5% (P: < 0.05) in regions surrounding areas of focal loss compared with comparable locations in control N eyes. After 3.5 months' elevated IOP the G retinas showed cell nuclei at various stages of apoptosis, from initial DNA condensation to fragmentation. CONCLUSIONS: The three-vein episcleral/limbal vein occlusion model for inducing glaucomatous pathology in the rat eye gives a consistent long-term elevation of IOP. After 3 to 4 months of approximately 100% increased IOP, the ERG responses begin to decline, there is a variable focal loss of RGCs, and some of the remaining RGCs show characteristics of stress and apoptosis. These changes seem consistent with retinal damage in human glaucoma (focal field defects), and this rat model appears to mimic some features of primary open-angle glaucoma.