盐酸氟桂嗪治疗高眼压性视网膜损伤

目的 观察家兔高眼压前、高眼压即刻及高眼压后用盐酸氟桂嗪对视网膜损伤的保护作用。方法 应用前房灌注加压法使前房内压力升至125．56mmHg，维持1h，恢复再灌注，在造成高眼压前12h，高眼压即刻及高眼压后12h用药。在再灌注7天，通过形态学及ERG的b波的观察，了解盐酸氟桂嗪对家兔视网膜损伤的保护作用。结果 高眼压前用药，ERG的b波可恢复至缺血前的85％左右。高眼压即刻及高眼压后用药可恢复至缺血前的60％左右，而未用药组则只能恢复43％左右。有统计学意义。功能民形态学变化一致。结论 盐酸氟桂嗪对家兔高眼压性视网膜损伤有保护作用。高眼压前用药比高眼压即刻及高眼压后用药作用更明显。     

氟桂嗪对兔眼视网膜缺血损伤的保护作用

目的探讨钙离子通道阻滞剂氟桂嗪对视网膜急性缺血损伤的保护作用.方法用ERG观察兔眼视网膜缺血再灌注不同时期a、b振幅的变化,比较对照组、实验组的差异.结果实验组b波振幅增加明显,与对照组比较,差异有显著性意义(P<0.01).两组中a波无变化(P>0.05).缺血30分钟b波振幅的恢复明显高于缺血60分钟.结论①氟桂嗪对急性视网膜缺血损伤具有保护作用.②细胞内钙离子超载参与了视网膜缺血损伤的病理、生理过程.     

氟桂嗪对视网膜缺血损伤保护作用的实验研究

目的：观察钙离子通道阻滞剂氟桂嗪（flunarizine）在视网膜缺血损伤中的保护作用。方法：用TBA法测定兔眼视网膜缺血再灌注不同时期脂质过氧化代谢产物丙二醛（MDA）含量变化，比较实验组、氟桂嗪治疗组的差异。结果：实验组、治疗组在缺血再灌注30，60，90min时与正常对照组相比MDA含量均有显著增加（P＜0.01）；氟桂嗪治疗组MDA含量在缺血再灌注30，60，90min3个时间段均明显低于实验组（P＜0.01）。结论:细胞内Ca^2 超载参与了视网膜组织缺血损伤的病理生理过程。氟桂嗪对急性视网膜缺血损伤具有保护作用。     

单唾液酸神经节苷酯对兔视网膜缺血再灌注损伤的保护作用

目的:通过监测视网膜电流图(ERG)a,b波恢复的百分率,观察单唾液酸神经节苷酯(GM-1)球后注射给药在视网膜缺血再灌注损伤中的保护作用.方法:健康新西兰大耳白兔20只,随机分为实验组和治疗组,用眼内灌注方法制成视网膜急性缺血的动物模型,治疗组于撤压前5 min球后注射GM-1(1 mg/kg),实验组只加压不给药,均记录缺血前ERG,缺血期ERG及再灌注30,60,90 min时的ERG图形.结果:两组缺血前的a,b波振幅无显著差异(P＞0.05).a波振幅的恢复在再灌注30,60及90 min两组间相比均无显著差异(P＞0.05).b波振幅的恢复在再灌注30,60及90 min两组间相比均有显著性的差异(两组间30,60及90 min比较均P＜0.01),治疗组均高于实验组.结论:单唾液酸神经节苷酯对视网膜缺血再灌注损伤具有保护作用.     

外源性神经生长因子对大鼠视网膜缺血再灌注损伤的保护作用

目的探讨外源性神经生长因子对大鼠视网膜缺血再灌注损伤的保护作用.方法建立结扎颈总动脉的大鼠视网膜缺血再灌注模型,分缺血再灌注组、缺血再灌注+外源性神经生长因子组.每组按再灌注时间的不同分为缺血再灌注1、6、12、24、48、72 h组.同时记录各期大鼠视网膜电图(electroretinogram,ERG)a、b波波幅,通过透射电镜观察各期视网膜的超微结构.结果缺血再灌注+外源性神经生长因子组各时期ERGa、b波波幅高于缺血再灌注组.视网膜超微结构显示缺血再灌注+外源性神经生长因子组细胞受损情况明显好于缺血再灌注组.结论外源性神经生长因子对大鼠视网膜缺血再灌注损伤具有保护作用.     

米诺环素对大鼠视网膜缺血再灌注的保护作用探讨

目的 探讨米诺环索对大鼠视网膜缺血再灌注损伤的保护作用.方法 SD大鼠88只,分为正常对照组8只,缺血组和治疗组各40只.建立视网膜缺血再灌注模型,于6、24、48、72 h检测视网膜电图(ERG)b波振幅,分光光度计测定超氧化物歧化酶(SOD),丙二醛(MDA),一氧化氮(NO)的变化,免疫组织化学检测半胱天冬酶-3(caspase-3)的表达,电镜观察超微结构.结果 与缺血组相比,治疗组可维持ERG b波振幅,升高SOD含量,降低MDA、NO含量,降低caspase-3表达,可减轻超微结构损伤(P＜0.05).结论 米诺环素可维持ERG b波振幅,调控SOD、MDA、NO,改善超微结构而保护视网膜.     

缺血再灌注损伤对大鼠视网膜功能的影响

目的 探讨缺血再灌注损伤对大鼠视网膜功能的影响。 方法 70只健康 Wistar 大鼠，预实验随机抽取 20 只分为正常对照组和单纯灌注组，记录视网膜电图（electroret inography，ERG）并测定b波峰值，经统计学处理无差异后，其余50只随机分为10组，用升高眼压1 h 的方法建立右眼视网膜缺血模型，分别于缺血后1 h及再灌注3、6、12 、24 h、3、5、7、14、21 d记录双眼暗视闪光 ERG并测定b波峰值。 结果 正常对照组动物左右眼ERG b波峰值无差异；单纯灌注眼与正常对照眼ERG b波峰值无差异；单纯缺血组实验眼ERG各波消失，再灌注实验眼组ERG b波部分恢复，但随再灌注时间的延长b波峰值呈进行性下降. 结论 视网膜缺血再灌注损伤可导致大鼠视网膜功能持续渐进性的影响。（中华眼底病杂志，2003，19：201-268）     

七叶甙对大鼠缺血再灌注损伤视网膜电图的影响

目的 :观察七叶甙对视网膜缺血再灌注损伤模型视网膜电图 (ERG)的影响。方法 :结扎大鼠左颈总动脉 1h ,然后再灌注 ,同时向腹腔注射七叶皂甙钠及异搏定 ,比较再灌注后 1h、6h、12h、2 4h、4 8h、72h视网膜ERG的变化。结果 :再灌注 6h后 ,七叶甙组、异搏定组视网膜的ERG与生理盐水组相比 ,有明显的提高 ,而七叶甙组和异搏定组相比 ,无明显的差异。结论 :七叶甙可以促进缺血再灌注损伤视网膜ERGb波的恢复     

己酮可可碱对大鼠急性高眼压性视网膜缺血再灌注损伤的保护作用

目的:探讨己酮可可碱对大鼠视网膜缺血再灌注损伤的保护作用及机制。方法:视网膜缺血再灌注模型是通过提高前房眼内压来实现的。将35只Wistar大鼠随机分为3组:正常组5只,对照组15只,治疗组15只。治疗组于高眼压前6h和眼压正常后即刻己酮可可碱50mg/kgip,对照组于相同时间点等容量生理盐水ip。监测视网膜电流图(ERG)b波的变化,测定视网膜谷氨酸含量以及视网膜线粒体钙含量。结果:治疗组和对照组谷氨酸含量都在缺血再灌注后逐渐上升,在48h达到峰值,两组都明显高于空白对照组(P<0.01)。在6h点治疗组与对照组间无显著差异,在其他时点对照组的Glu含量明显高于治疗组(P<0.05)。治疗组和对照组视网膜线粒体钙含量在缺血再灌注后逐渐上升,在24h达到峰值,然后逐渐下降。两组都明显高于空白对照组(P<0.01)。在6h点治疗组与对照组间无显著差异,在其他时点对照组的视网膜线粒体钙浓度明显高于治疗组(P<0.05)。再灌注后,对照组ERGb波比较低平;再灌注后1h,对照组、治疗组的ERG相对b波无明显的差异。24h后两组b波都降低到最低,然后逐渐恢复;72h后对照组ERGb波仅恢复到正常眼的69%左右。己酮可可碱处理组ERGb波恢复到正常眼的95%左右,ERGb波明显较对照组高(P<0.01)。结论:己酮可可碱能有效降低视网膜谷氨酸含量及视网膜组织细胞线粒体钙离子含量,促进ERGb波的恢复,缩短了视网膜缺血再灌注的病理过程。对大鼠视网膜缺血再灌注损伤有一定的保护作用。     

核转录因子-κB及细胞间粘附分子-1在大鼠视网膜缺血再灌注损伤中的表达及吡咯醛二硫氨基甲酸酯对两者表达的影响

目的 探讨核转录因子-κB(NF-κB)及细胞间粘附分子(ICAM)-1在大鼠视网膜缺血再灌注损伤中的表达及吡咯醛二硫氨基甲酸酯（PDTC）对两者表达的影响。 方法 建立大鼠视网膜缺血再灌注模型，60只SD大鼠随机分为缺血再灌注组和缺血再灌注+PDTC治疗组，每组30只大鼠。每只大鼠结扎左侧颈总动脉，右侧未作结扎作为对照。每组按再灌注后不同时间段再分为1、6、12、24、48、72 h组，每组5只大鼠。以原位杂交法检测视网膜中NF-κB和ICAM-1的表达，每只大鼠在1、6、12、24、 48、72 h相应时间段行断颈处死前均行视网膜电图（ERG）检测，并分别计算出左眼或右眼E RG a、b波波幅的比值，得出ERG a、b波的相对恢复率。 结果 缺血再灌注组在再灌注后6 h开始检测到NF-κB和ICAM-1的表达，在24 h表达最强，以后逐渐减弱 。缺血再灌注+PDTC组在再灌注后6 h未检测到NF-κB和ICAM-1的表达，在12 h有NF-κB 和ICAM-1的表达，24 h表达最强，但低于缺血再灌注组。对照组未检测到NF-κB和ICAM-1的表达。缺血再灌注各组ERG a、b波波幅相对恢复率低于缺血再灌注+PDTC组(P＜0.01 )。缺血再灌注与缺血再灌注+PDTC组各时间段ERG a、b波波幅相对恢复率以再灌注后24 h最差（P＜0.01）。 结论 NF-κB及其诱导的ICAM-1在视网膜缺血再灌注损伤中发挥重要作用，PDTC可能通过抑制NF-κB的活性减轻视网膜缺血再灌注损伤。 （中华眼底病杂志，2004，20：175-178）     

Topical flunarizine reduces IOP and protects the retina against ischemia-excitotoxicity

PURPOSE: To determine whether topical application of flunarizine reduces intraocular pressure (IOP) and acts as a retinal neuroprotectant and to compare the effectiveness of flunarizine with betaxolol and nifedipine at reducing the influx of calcium and sodium. METHODS: Ischemia was delivered to the rabbit retina by raising the IOP. After 3 days, a flash electroretinogram (ERG) was recorded, and the retina processed for the localization of certain antigens. In the rat, N-methyl-D-aspartate (NMDA) was injected intravitreally, and 8 days later, the retinas were analyzed for the localization of Thy-1 or the relative amounts of mRNAs for antigens located to ganglion cells or photoreceptors. Rats and rabbits received topical flunarizine or vehicle before and after ischemia or NMDA. IOP was measured in rabbits after a single topical application of 2% flunarizine. Studies were conducted on isolated rat retinas, cortical cultures, and brain synaptosomes to compare the effectiveness of flunarizine with nifedipine and betaxolol at reducing the influx of calcium or sodium. RESULTS: Changes in rabbit retinal choline acetyltransferase and parvalbumin immunoreactivities and the b-wave of the ERG caused by ischemia-reperfusion were blunted by topical treatment with flunarizine. Similarly, NMDA induced reductions in Thy-1 immunoreactivity and mRNA for rat ganglion cell antigens (Thy-1 and neurofilament light form) were counteracted by topical application of flunarizine. Topical application of 2% flunarizine significantly lowered the IOP in rabbits over a period of 5 hours. Flunarizine was more effective than betaxolol and much stronger than nifedipine at attenuating veratridine-induced influx of sodium into synaptosomes. Nifedipine, flunarizine, and betaxolol all reduced the NMDA-induced influx of calcium into the isolated retina or cortical neurons, but betaxolol was the least effective. CONCLUSIONS: Topically applied flunarizine reduces IOP and attenuates injury to the whole of the retina, including the ganglion cells. The neuroprotective action of flunarizine is to reduce the influx of calcium and sodium into stressed neurons. The potent effect of flunarizine on sodium influx would be particularly protective to axons.     

Lomerizine, a Ca2+ channel blocker, reduces glutamate-induced neurotoxicity and ischemia/reperfusion damage in rat retina

We examined the effects of a new Ca2+ channel blocker, lomerizine, on the intraocular hypertension-induced ischemia/reperfusion injury in rat retina and on the glutamate-induced neurotoxicity in rat cultured retinal neurons, and compared its effects with those of a Ca2+ channel blocker (flunarizine) and an N-methyl-D-aspartate receptor antagonist (MK-801). Morphometric evaluation at 7 days after ischemia/reperfusion showed that treatment with lomerizine (0.1 and 1 mg kg(-1), i.v.) prior to ischemia and again immediately after reperfusion dose-dependently reduced the retinal damage. Treatment with MK-801 (1 mg kg(-1), i.v.) before ischemia significantly reduced the resulting retinal damage. Flunarizine (0.1 and 1 mg kg(-1), i.v.) tended to reduce the retinal damage, but its effect did not reach statistical significance. In an in vitro study, pretreatment with lomerizine (0.1 and 1 microM) or flunarizine (1 microM) significantly reduced glutamate-induced neurotoxicity, the effects being concentration dependent. Lomerizine (1 microM) also exhibited protective effects against both the N-methyl-D-aspartate and kainate induced types of neurotoxicity. However, lomerizine (1 microM) had little effect on the neurotoxicity induced by ionomycin (1 microM) application. Glutamate-induced neurotoxicity was abolished by removing Ca2+ from the medium. These results indicate that lomerizine protects neuronal cells against retinal neurotoxicity both in vivo and in vitro, and that this Ca2+ channel blocker may be useful as a therapeutic drug against retinal diseases that cause neuronal injury, such as normal tension glaucoma (NTG).     

碱性成纤维细胞生长因子对鼠视网膜缺血再灌注损伤的治疗作用

目的　探讨碱性成纤维细胞生长因子 (bFGF)在大鼠视网膜缺血再灌注损伤中的治疗作用。方法　 4 0只大鼠采用升高眼内压的方法建立大鼠视网膜缺血再灌注模型作为手术组 ,该组大鼠左眼于玻璃体腔中注入赋形剂 (缺血组 ) ,右眼于玻璃体腔中注入bFGF(治疗组 ) ;另外 4只大鼠为正常组。手术组于再灌注后 1、6、12、2 4及 72h分别应用末端脱氧核酸转移酶介导的脱氧三磷酸尿苷缺口末端标记法检测视网膜组织中凋亡细胞的表达 ,采用过氧化物酶标记的链酶卵白素免疫组化方法检测caspase 3的表达 ,使用原子吸收光度计测定细胞内钙离子的变化。 结果　缺血组再灌注 6h大鼠视网膜出现凋亡细胞 ,并随时间依次增加 ,至 2 4h达高峰 ,72h时几乎未发现凋亡细胞。caspase 3表达改变与凋亡细胞表达相似。细胞内钙离子含量于再灌注后 1h开始升高 ,至 2 4h达到高峰 ,72h出现下降。治疗组各观察指标变化规律基本同上 ,但再灌注 12、2 4h时的凋亡细胞数目明显低于缺血组 (P <0 0 5 ) ;于 6、12及 2 4h ,caspase 3的表达较缺血组明显下降 (P <0 0 5 ) ;于 6、12、2 4及 72h ,细胞内钙离子含量均明显低于缺血组 (P <0 0 5 )。结论　细胞凋亡可能在视网膜缺血再灌注损伤过程中起重要作用 ,bFGF可通过对细胞内钙离子、自由基及凋     

大鼠视网膜缺血再灌注损伤后碱性成纤维细胞生长因子对热休克蛋白70表达的影响

目的 观察大鼠视网膜缺血再灌注损伤后热休克蛋白70(HsP70)的表达以及外源性碱性成纤维细胞生长因子(bFGF)对其表达的影响。 方法 采用升高眼内压的方法，制作实验性视网膜缺血再灌注损伤大鼠模型。将24只wistar大鼠随机分为正常组(3只)和手术组(21只)。其中手术组大鼠左眼为缺血再灌注组，右眼为bFGF治疗组(玻璃体腔内注射bFGF 2肛g)，手术组根据再灌注后不同时间分为。、4、8、12、24、48、72 h组。应用免疫组织化学方法观察大鼠视网膜缺血再灌注损伤后视网膜内层组织中HsP70的表达及玻璃体腔内注射外源性bFGF对其表达的影响。 结果 对照组无阳性细胞表达。缺血再灌注组中，缺血再灌注O h后即可见HsP70的表达[(20．8±4．5)个／mm。]，并随时间延长而逐渐增加，至24 h达到高峰[(111．2±4．4)个／mm z]，随后阳性细胞递减，72 h时偶见阳性细胞。bFGF治疗组HsP70的表达变化规律与缺血组基本一致，但在8、12、24、48、72 h时均较缺血再灌注组显著增高(P<0.05).相似文献   

大鼠视网膜缺血再灌注后细胞间粘附分子-1的表达

目的　探讨大鼠视网膜缺血再灌注后不同时间视网膜细胞间粘附分子 1(inter cellularadhesionmolecule 1,ICAM 1)表达和白细胞浸润的变化。方法　选择健康成年Wistar大鼠 70只 ,随机分成 7组 :正常组和再灌注 0、2、6、12、2 4、4 8h组 ,每组 10只。用眼内灌注法建立视网膜缺血再灌注动物模型。制作大鼠视网膜冰冻及石蜡切片 ,分别作免疫组化SP染色和常规HE染色 ,并对SP染色结果作计算机图像分析。结果　ICAM 1在正常视网膜血管内皮细胞胞膜微量表达 ,缺血 6 0min后 ,ICAM 1表达上调 ,至再灌注2 4h达高峰 ,在再灌注 4 8h仍维持较高水平。再灌注 6h ,视网膜开始有白细胞浸润 ,随再灌注时间延长而增多 ,再灌注 2 4、4 8h组 ,视网膜中发现较多浸润的白细胞。结论　视网膜缺血再灌注早期 ,视网膜血管内皮细胞ICAM 1表达上调 ,继而 ,视网膜中白细胞浸润增多 ,这一过程是视网膜缺血再灌注损伤的重要机制之一。     

Memantine reduces alterations to the mammalian retina, in situ, induced by ischemia

The aim of the study was to determine whether memantine could slow down the changes seen in the rabbit and rat retina following ischemia/reperfusion. A "suction cup procedure," which raises the intraocular pressure, was used to give an ischemic insult to the rabbit retina. The electroretinogram was recorded before ischemia and after 2 days of reperfusion. Memantine or saline (10 microl) was injected into the eye before ischemia. Immunohistochemistry was used to study the effect of ischemia/reperfusion on the GABA, ChAT, and alphaPKC immunoreactivities. Ischemia/reperfusion injury to the rat retina was induced by raising the intraocular pressure above the systolic blood pressure for 60 min, followed by reperfusion of 3-14 days. Memantine (5 mg/kg) or saline was injected i.p. at the onset of ischemia or reperfusion. Immunohistochemistry was used to study the effect of ischemia/reperfusion on the ChAT, alphaPKC, and Thy-1 immunoreactivities. In addition, morphometric analysis was carried out to determine the effects of ischemia/reperfusion on the thickness of the retina. Ischemia for 75 min caused a change in the nature of the normal GABA and ChAT immunoreactivities in the rabbit retina and a reduction in the b-wave of the electroretinogram. When memantine was injected into the vitreous humour at the onset of an ischemic insult, the changes in the GABA and ChAT immunoreactivities were reduced and the recovery of the reduced b-wave of the electroretinogram after 2 days reperfusion was enhanced significantly. Ischemia for 60 min followed by 3 days reperfusion showed a clear change in ChAT immunoreactivity in the rat retina. The Thy-1 immunoreactivity was only clearly altered after a reperfusion period of 7 days. Moreover, a measurable change in the thickness of the inner retinal layers was detected after 14 days of reperfusion. When given at the onset of ischemia, memantine counteracted the effect of ischemia/reperfusion to varying degrees. However, when memantine was given at the onset of the reperfusion this was not the case. The combined data show that a single injection of memantine given i.p. or intravitreally will protect the retina from a subsequent ischemic insult.     

溴莫尼定对视网膜缺血性损伤神经保护作用的实验研究

目的：探讨溴莫尼定(brimonidine)对视网膜缺血性损伤神经的保护作用。方法：新西兰大耳白兔32只，随机分为正常对照组、生理盐水治疗组、噻吗心安(timolol)治疗组、brimonidine治疗组，每组8只。后3组为损伤治疗组，通过生理盐水前房高压灌注的方法，制成视网膜缺血动物模型，在视网膜缺血前lh其结膜囊内分剐给予生理盐水、0．5％timolol眼液或0．2％brimonidine眼液局部治疗。在灌注后7d，观察图形视网膜电图(P-ERG)b波振幅变化，并进行组织形态学观察和视网膜神经节细胞(RGC)计数分析。结果：灌注后7d，3个损伤治疗组相对b波振幅恢复率为：7％、11％和64％，RGC标准丢失率为：43％、38％和12％，brimori-die治疗组视网膜组织形态结构接近正常对照组，而生理盐水治疗组和timolol治疗组视网膜内层组织结构损伤明显。结论：Brimonidine局部治疗对缺血诱导的视网膜结构和功能的损害有明显的神经保护作用。     

Administration of 17beta-estradiol attenuates retinal ischemia-reperfusion injury in rats

PURPOSE: Accumulating evidence has suggested that 17beta-estradiol exerts protective effects against ischemic damage in various organs. In addition, leukocytes that accumulate in postischemic tissues are thought to play a central role in ischemia-reperfusion injury. This study was designed to evaluate quantitatively the inhibitory effects of 17beta-estradiol on leukocyte accumulation during ischemia-reperfusion injury and on subsequent retinal damage after transient retinal ischemia. METHODS: Transient (60 minutes) retinal ischemia was induced in male rats by temporary ligation of the optic nerve. Thirty minutes before induction of ischemia, 17beta-estradiol (0.1 mg/kg) was administered intraperitoneally. At 6, 12, 24, and 48 hours after reperfusion, leukocyte accumulation in the retina was evaluated in vivo by means of acridine orange digital fluorography. Histologic and electroretinographic (ERG) studies were carried out to evaluate retinal damage. RESULTS: Treatment with 17beta-estradiol significantly inhibited postischemic leukocyte accumulation; the maximum number of accumulating leukocytes was reduced by 35.7% at 24 hours after reperfusion (P = 0.01). Histologic examination showed that administration of 17beta-estradiol significantly reduced retinal damage, which was most obvious in the inner retina, 168 hours after reperfusion (P = 0.0001). ERG studies at 12 and 168 hours after reperfusion showed that recovery of the b-wave amplitude was significantly improved with treatment of 17beta-estradiol (P = 0.023). CONCLUSIONS: The present study demonstrated the inhibitory effects of 17beta-estradiol on leukocyte accumulation and subsequent tissue injury during retinal ischemia-reperfusion injury.     

Heme oxygenase-1 induced in muller cells plays a protective role in retinal ischemia-reperfusion injury in rats

PURPOSE: To investigate the protective roles played by heme oxygenase (HO)-1 and -2 in the rat retina after ischemia-reperfusion injury. METHODS: Retinal ischemia was induced in rats by increasing the intraocular pressure to 110 mmHg for 60 minutes. The expression of HO-1 and -2 in the retina was determined by Western blot, real-time polymerase chain reaction (PCR), and immunohistochemistry. To inhibit the upregulation of HO-1, short interfering (si)RNA of HO-1 was injected intravitreally before ischemia and that of green fluorescent protein (GFP) was used as the control. Muller cell damage was assessed by counting the number of S-100-positive cells. The number of macrophages invading the retina was determined by counting the number of ED-1-positive cells. RESULTS: The expression of HO-1 mRNA and protein was upregulated at 6 hours after reperfusion and peaked at 12 to 24 hours, whereas that of HO-2 was not altered. HO-1 immunoreactivities were detected in Muller cells at 24 hours after reperfusion, and HO-2 immunoreactivities were detected in retinal cells. The HO-1 expression in the retina treated with siRNA of HO-1 was reduced at 12 and 24 hours after reperfusion compared with that injected with siRNA of GFP. The number of S-100-positive cells at 24 hours after reperfusion decreased significantly in retinas treated with HO-1 siRNA (P <0.01). The number of macrophages that had infiltrated the retina was increased in retinas pretreated with the siRNA of HO-1 compared with those treated with siRNA of GFP. On day 14 after reperfusion, HO-1 siRNA-treated retinas showed severe retinal injury and destruction of the retinal architecture. CONCLUSIONS: HO-1 promotes the survival of Muller cells after ischemia-reperfusion injury. Because inhibition of the upregulation of HO-1 resulted in an infiltration of inflammatory cells and destruction of the retina, the authors conclude that HO-1 induced in Muller cells plays a protective role in retinal ischemia-reperfusion.     

Inhibitory effect of ischemic preconditioning on leukocyte participation in retinal ischemia-reperfusion injury

PURPOSE: Recent reports have shown that ischemic preconditioning induces strong protection against retinal damage by subsequent prolonged ischemia and that this protection is mediated by mechanisms involving the adenosine A1 receptor. This study was designed to evaluate quantitatively the effects of ischemic preconditioning on leukocyte-mediated reperfusion injury after transient retinal ischemia and to define the role of the adenosine A1 receptor in these effects. METHODS: Transient retinal ischemia was induced in male rats by temporary ligation of the optic nerve. Ischemic preconditioning (5 minutes of ischemia) was induced 24 hours before 60 minutes of ischemia. The adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) was administered intramuscularly immediately after ischemic preconditioning. Leukocyte behavior in the retina after 60 minutes of ischemia was evaluated in vivo with acridine orange digital fluorography. RESULTS: Ischemic preconditioning inhibited leukocyte rolling. The maximum number of rolling leukocytes was reduced to 3.0% at 12 hours after reperfusion (P < 0.01). Subsequent leukocyte accumulation was also decreased with ischemic preconditioning. The maximum number of accumulated leukocytes was reduced to 22.6% at 24 hours after reperfusion (P < 0.01). These inhibitory effects were suppressed by administration of DPCPX (P < 0.0001). The numbers of rolling leukocytes at 12 hours after reperfusion and accumulated leukocytes at 24 hours after reperfusion were 102.7% (NS) and 83.4% (P < 0.01), respectively, compared with the number without ischemic preconditioning. CONCLUSIONS: The present study demonstrates the inhibitory effects of ischemic preconditioning on leukocyte rolling and subsequent leukocyte accumulation during retinal ischemia-reperfusion injury. Furthermore, the adenosine A1 receptor may play an important role in these inhibitory effects.