Retinal ischemia-reperfusion injury attenuated by blocking of adhesion molecules of vascular endothelium

PURPOSE: To evaluate quantitatively the effects of blocking of adhesion molecules (P-selectin or intercellular adhesion molecule-1 [ICAM-1]) on leukocyte dynamics in the retinal microcirculation in vivo during ischemia-reperfusion injury and the therapeutic efficacy of the blocking of adhesion molecules on retinal ischemia-reperfusion injury. METHODS: Retinal ischemia was induced for 60 minutes in anesthetized pigmented rats by temporary ligation of the optic nerve. P-selectin or ICAM-1 monoclonal antibody (mAb) was administered at 5 minutes before reperfusion. At 4, 12, and 24 hours after onset of reperfusion, leukocyte behavior in the retinal microcirculation was evaluated in vivo with acridine orange digital fluorography. After 7 or 14 days of reperfusion, retinal damage was evaluated histologically. RESULTS: P-selectin mAb significantly inhibited leukocyte rolling along the major retinal veins after reperfusion. Subsequently, the number of accumulated leukocytes decreased in the P-selectin-inhibited rats. ICAM-1 mAb also inhibited leukocyte accumulation during the reperfusion period in a more substantial manner than P-selectin mAb. Histologic examination demonstrated the protective effect of the blocking of P-selectin or ICAM-1. In accordance with a reduction in leukocyte accumulation, the protective effect of mAb on retinal ischemia-reperfusion injury was more substantial in ICAM-1-inhibited rats. CONCLUSIONS: The present study demonstrates the inhibitory effect of P-selectin and ICAM-1 mAb on leukocyte accumulation and subsequent tissue injury during retinal ischemia-reperfusion injury.     

VEGF increases retinal vascular ICAM-1 expression in vivo.

PURPOSE: Intraocular injections of vascular endothelial growth factor (VEGF), a peptide implicated in the pathogenesis of diabetic retinopathy, can induce retinal ischemia. Diabetic retinal ischemia may be caused, in part, by the adhesion of leukocytes to the retinal vasculature. In this study, the ability of VEGF to increase the expression of intercellular adhesion molecule-1 (ICAM-1) and other adhesion molecules in capillary endothelium and the retinal vasculature was examined. METHODS: The expression of ICAM-1, vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and P-selectin on human brain capillary endothelial cell monolayers exposed to VEGF was quantitated by immunoassay. The effect of VEGF on retinal vascular ICAM-1 expression was determined in ICAM-1 immunofluorescence studies of retinal flat-mounts and in RNase protection assays. RESULTS: VEGF increased capillary endothelial cell ICAM-1 levels in a dose- and time-dependent manner (6-24 hours, plateau after 6 hours; EC50, 25 ng/ml). VEGF failed to alter E-selectin, P-selectin, or VCAM-1 levels under the conditions tested. Intravitreal injections of pathophysiologically relevant concentrations of VEGF increased ICAM-1 protein and mRNA levels in the retinal vasculature. CONCLUSIONS: VEGF increases retinal vascular ICAM-1 expression. VEGF-induced increases in ICAM-1 may promote retinal leukostasis in diabetic eyes.     

Leukocyte trafficking in experimental autoimmune uveitis: breakdown of blood-retinal barrier and upregulation of cellular adhesion molecules

PURPOSE: To clarify the order of events occurring in the breakdown of the blood-retinal barrier (BRB) in experimental autoimmune uveoretinitis (EAU) and in particular to study the relationships between increased vascular permeability, upregulation of endothelial cell adhesion molecules, and leukocyte adhesion and infiltration during EAU. METHODS: B10.RIII mice were immunized with human interphotoreceptor retinoid binding protein (IRBP) peptide 161-180. Changes in the retinal microvasculature were examined on days 3, 6, 7, 8, 9, 10, 16, and 21 postimmunization (pi). Evans blue dye was administered intravenously to assess vascular permeability. Expression of intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, P-selectin, E-selectin, and platelet endothelial cell adhesion molecule (PECAM)-1 was evaluated by in vivo administration of antibody and subsequent immunostaining of retinal wholemounts. Lymphocytes from inguinal lymph nodes of normal and chicken ovalbumin (OVA)- or IRBP peptide-immunized mice at day 5, 6, 7, 8, and 15 pi were labeled in vitro with calcein-AM (C-AM) and infused intravenously into syngeneic recipient mice, which had been immunized with peptide at the same corresponding time point. Wholemount preparations of retinas were observed 24 hours later by confocal microscopy to determine the adhesion and infiltration of lymphocytes. RESULTS: The first observation of an increase in vascular permeability occurred at day 7 pi and was restricted to focal areas of the retinal postcapillary venules of the inner vascular plexus. This progressively extended to the outer vascular plexus at day 9 pi. Specific adhesion of leukocytes to the endothelium of retinal venules of the inner vascular plexus was first observed at day 6 pi. Leukocyte extravasation into the retinal parenchyma from these vessels began at day 8 pi and extended to the outer vascular plexus at day 9 pi. The expression of adhesion molecules increased progressively during the development of EAU. In particular, the adhesion molecules ICAM-1, P-selectin, and E-selectin were expressed predominately in retinal venules, the sites of BRB breakdown, cell adhesion, and extravasation, from day 7 pi. The increases in expression of ICAM-1 and P-selectin were associated both spatially and temporally with breakdown of the BRB, cell adhesion, and extravasation. No increase in expression of P-selectin and ICAM-1 was observed in either the mesenteric vessels of EAU mice or the retinal vessels of OVA-immunized mice. CONCLUSIONS: The sequence of events in EAU appears to be focal adhesion of leukocytes to discrete sites on postcapillary venules, followed by upregulation of adhesion molecules, especially ICAM-1 and P-selectin, and breakdown of the BRB, leading to transendothelial migration of leukocytes and recruitment of large numbers of cells to the retinal parenchyma. These changes occur over a short period of 6 to 9 days pi and initiate the process of tissue damage during the following 2 to 3 weeks.     

In vivo evaluation of platelet--endothelial interactions after transient retinal ischemia

PURPOSE: Accumulating evidence suggests that platelets play an important role in ischemia-reperfusion injury. To fulfill that role, platelets flowing in the bloodstream would have to interact with retinal endothelial cells and to accumulate in the postischemic retina. This study was designed to investigate quantitatively platelet-endothelial interactions in postischemic retina after transient retinal ischemia. METHODS: Transient retinal ischemia was induced in Long-Evans rats for 60 minutes by temporal ligation of the optic nerve. Isolated platelet samples labeled with carboxyfluorescein diacetate succinimidyl ester were administered intravenously to recipient rats after various reperfusion periods. Platelet-endothelial interactions in postischemic retina were evaluated in vivo with a scanning laser ophthalmoscope. Anti-P-selectin monoclonal antibody (mAb) was administered 5 minutes before the injection of labeled platelets. P-selectin gene expression in the postischemic retina was studied by semiquantitative polymerase chain reaction. RESULTS: Under basal conditions, infused platelets showed minimal interactions with retinal endothelial cells. In contrast, postischemic retinas showed active platelet-endothelial interactions. Many platelets were observed rolling along and adhering to the major retinal veins. The number of rolling and adhering platelets reached a peak (555 +/- 65/mm per min and 25.8 +/- 3.2/mm(2)) 12 hours after reperfusion. However, the interactions between platelets and postischemic retinal endothelial cells were substantially inhibited by neutralizing P-selectin expressed on endothelial cells. In addition, P-selectin gene expression in postischemic retina corresponded with the time course of platelet-endothelial interactions during the reperfusion period. CONCLUSIONS: This study demonstrated that platelets actively interacted with retinal endothelial cells in the postischemic retina through P-selectin expressed on the retinal endothelial cells.     

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     

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.     

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.     

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.     

大鼠视网膜缺血-再灌注损伤超微结构观察及机制探讨

目的研究大鼠视网膜缺血-再灌注损伤中的超微结构改变以及凋亡相关基因表达的变化,探讨其损伤机制。方法将28只大鼠随机分为正常组和手术组,手术组按照再灌注后不同时间段分为1h、6h、12h、24h、48h、72h组。前房加压法制作大鼠视网膜缺血-再灌注损伤模型,透射电镜检测视网膜超微结构改变,免疫组织化学法检测视网膜组织中bcl-2、bax、Fas的表达。结果(1)正常组视网膜神经纤维中微管及线粒体清晰可见;视网膜神经节细胞(retinal ganglion cells,RGCs)核大,电子密度低,核仁明显,细胞器丰富;再灌注损伤后RGCs核膜肿胀,线粒体嵴模糊不清,可见凋亡小体,神经纤维中微管模糊、减少甚至消失,以再灌注后24h为甚;(2)再灌注后6h,bax表达逐渐递增,24h达到高峰,48h开始下降,72h不明显;(3)bcl-2在视网膜神经节细胞层、纤维层及内核层有微弱表达,各个时间段变化不明显;(4)Fas表达改变与bax基本一致。结论视网膜缺血-再灌注损伤中,细胞凋亡是引起视网膜内核层和神经节细胞层细胞死亡的主要方式,其损伤机制与凋亡相关基因bcl-2、bax、Fas的表达变化有关。     

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。     

In vivo evaluation of leukocyte dynamics in the retinal and choroidal circulation

We have developed a new method to visualize leukocytes and evaluate their kinetics in the chorioretinal microcirculation of the living eyes. Nuclear staining dyes and a scanning laser ophthalmoscope were used to image leukocytes in the fundus. Acridine orange was used to visualize leukocytes in the retinal microcirculation. For imaging leukocytes in the choroid, indocyanine green was injected intravenously. Dynamics of leukocytes in the capillaries of the retina and choroid were quantitatively estimated in monkeys and rats. This method also allowed evaluation of leukocyte-endothelial interactions, such as rolling or firm adhesion, in vivo. Acridine orange leukocyte fluography was used to study leukocyte dynamics in the following experimentally induced microcirculatory disturbances of the retina: 1) interferon-associated retinopathy, 2) ischemia-reperfusion injury of the retina, and 3) experimental diabetes mellitus. 1) Interferon-associated retinopathy Systemic administration of interferon alpha enhanced leukocyte-endothelial interactions in the retina, which resulted in leukocyte rolling and entrapment in the retinal capillary beds. Leukocyte accumulation was also detected in the lung. The entrapment or accumulation of leukocytes in the microcirculation was inhibited by simultaneous administration of corticosteroids or other agents. These results suggested that leukocytes play a major role in the development of adverse effects of interferon, such as retinopathy or interstitial pneumonia. 2) Ischemia-reperfusion injury of the retina During reperfusion period after transient (60 min) retinal ischemia by optic nerve ligation, the rolling of leukocytes in the retinal veins was prominent and numerous leukocytes were trapped in the retinal capillaries. The number of rolling leukocytes was at a maximum 12 hours after reperfusion. Leukocyte entrapment peaked at 24 hours after reperfusion. By blocking adhesion molecules on the vascular endothelium, these leukocyte-endothelial interactions were effectively inhibited. Postischemic retinal atrophy was also inhibited by blocking adhesion molecules. These results suggested that leukocytes may be major players in the pathophysiology of ischemia reperfusion injury of the retina. 3) Experimental diabetes mellitus Leukocyte dynamics in the retina were studied in streptozotocin-induced diabetes and spontaneous diabetes (OLETF rats). In both diabetic models, leukocyte entrapment in the retinal capillaries was increased even in the early stages of diabetes. Fluorescein angiography revealed that trapped leukocytes disturbed the regional capillary blood flow in the downstream. Enhanced expression of adhesion molecules was observed in the capillary endothelium of the retina in the diabetic rats. Leukocyte entrapment in the retinal capillaries might cause microvascular occlusions and dysfunction, in turn causing diabetic retinopathy.     

Differential temporal and spatial expression of immediate early genes in retinal neurons after ischemia-reperfusion injury

PURPOSE: To investigate genes that are up- and downregulated in rat retinal ischemia-reperfusion injury systematically by using an oligonucleotide microarray system and to determine temporal and spatial expression changes of some genes that showed upregulation in the analysis. METHODS: Retinal ischemia was induced in rats by increasing intraocular pressure to 110 mm Hg for 1 hour. Gene expression at 12 hours after reperfusion was compared with that in the control retina by using oligonucleotide microarrays that display a total of 8800 genes and expressed sequence tags (ESTs). Temporal and spatial expression changes of immediate early genes and cell-cycle-related genes were studied by using real-time polymerase chain reaction (PCR) and immunohistochemical methods. RESULTS: At 12 hours after reperfusion, 135 genes and ESTs were found to be up- or downregulated. The upregulated genes were classified into seven groups: (1) immediate early genes; (2) cell-cycle-related genes; (3) stress-responsive protein genes; (4) cell-signaling protein genes; (5) cell-adhesion and cell surface protein genes; (6) genes for translation and protein turnover; and (7) genes for metabolism. Real-time PCR analyses showed peaks of Fra-1 expression at 6 hours after reperfusion, whereas those for c-Jun, Jun B, and cyclin D1 were at 24 hours. Fra-1 and Jun B immunoreactivities were found in Müller cells, whereas c-Jun and cyclin D1 immunoreactivities were found in apoptotic retinal neurons. CONCLUSIONS: Gene expression changes after a retinal ischemia-reperfusion injury were profiled by using an oligonucleotide microarray system. Seven groups of genes were found to be upregulated by the injury. Among the immediate early genes, Fra-1 and Jun B immunoreactivities were found in Müller cells whereas c-Jun and cyclin D1 immunoreactivities were found in apoptotic retinal neurons.     

Upregulation of stromal cell–derived factor 1 (SDF-1) expression in microvasculature endothelial cells in retinal ischemia-reperfusion injury

Background  Stromal cell–derived factor 1 (SDF-1) is a potent chemotactic and angiogenic factor that has been proposed to play a role in the development of neovascularization. In this study, we explored the expression of SDF-1 in a rat model of retinal ischemia-reperfusion injury and investigated the possible role of retinal microvasculature endothelium cells in generation of this chemokine. Methods  Expression patterns of SDF-1 were studied in retina suffering ischemia-reperfusion insult in Sprague-Dawley rats by elevating the intraocular pressure to 110 mm for 60 minutes. The relative level of SDF-1 mRNA in retinas following 6, 12 and 24 hours reperfusion was determined by semi-quantitative RT-PCR. Immunohistochemical methods were used to detect specific lesions expressing SDF-1. The gene expression of SDF-1 in cultured human retinal microvasculature endothelial cells (HRMEC) under hypoxia conditions was assessed by semi-quantitative RT-PCR. The SDF-1 protein was analyzed by immunocytochemistry and fluorescence-activated cell sorting. Results  Upregulation of SDF-1 mRNA (at 6, 12, and 24 hours of reperfusion) was observed, with the expression peak occurring at 12 hours. SDF-1 positive cells appeared initially around the retinal vessels,which diffused into the inner retinal layers. Hypoxia enhanced the expression of HIF-1 and SDF-1 mRNA in HRMEC. The production of SDF-1 protein by HRMEC was increased up to 320% after 6 hours of hypoxia, as demonstrated by fluorescence-activated cell sorting. Conclusions  The results of our study indicate that endogenous SDF-1 is up-regulated in retinal microvasculature suffering ischemia insult, and that microvasculature endothelial cells are potential contributors for generation of SDF-1 in ischemic retina. We don’t have any financial relationship with the organization that sponsored the research. We have full control of all primary data, and agree to allow Graefe’s Archive for Clinical and Experimental Ophthalmology to review these data.     

Effects of periocular administration of triamcinolone acetonide on leukocyte-endothelium interactions in the ischemic retina

PURPOSE: Recent studies have reported that intravitreal or posterior sub-Tenon's injection of triamcinolone acetonide (TA) is effective in the treatment of macular edema resulting from retinal microcirculatory disturbances such as diabetic retinopathy and retinal vein occlusion. The effects of periocular administration of TA on leukocyte-endothelium interactions were studied after transient retinal ischemia. METHODS: Transient retinal ischemia was induced by temporary ligation of the optic nerve sheath for 60 minutes in male Long-Evans rats. After the induction of ischemia, experimental eyes received a periocular injection of TA (2 mg). In control animals, the same volume of saline was administered. Leukocyte dynamics were evaluated in the retinal microcirculation using acridine orange digital fluorography. Also, retinal thickness was studied by using optical coherence tomography and a histologic METHOD: The retinal mRNA expression of P-selectin and intercellular adhesion molecule (ICAM)-1 was semiquantitatively studied with RT-PCR. RESULTS: The leukocytes rolling along retinal vein linings increased after ischemia in the vehicle-treated rats (32.5 +/- 2.1 cells/min). No rolling leukocytes, however, were seen in the TA-treated rats. The number of accumulated leukocytes was significantly lower in the TA-treated rats (831 +/- 99 cells/mm2) than in the control (971 +/- 81 cells/mm2, P < 0.05). The treatment decreased the retinal thickness and the mRNA expression of P-selectin and ICAM-1. CONCLUSIONS: The present study demonstrated that the periocular injection of TA effectively decreased retinal thickness and inhibited leukocyte-endothelium interactions in the retina after ischemia. Downregulation of adhesion molecules of retinal vascular endothelium induced by TA may play a role in the course.     

iNOS mRNA在缺血再灌注损伤鼠视网膜中的表达

目的　研究iNOSmNRA在缺血再灌注过程鼠视网膜中的表达 ,探讨NO对视网膜缺血再灌注损伤的作用和意义。方法　动物模型采用升高眼压造成视网膜缺血 ,再恢复正常眼压形成血流再灌注。用Biotin标记iNOScRNA探针进行分子原位杂交。结果　正常组、对照组视网膜没有iNOSmRNA表达 ;再灌注 3、12、2 4h均有iNOSmRNA表达 ,与正常组相比差异有显著性 (P <0 0 1) ,并且再灌注 12hiNOSmRNA表达量最高 ,明显高于其他实验组 (P <0 0 1) ;再灌注48、96h没有发现iNOSmRNA表达。结论　在缺血再灌注过程视网膜有较高的iNOSmRNA表达 ,iNOS催化产生的NO可能参与了视网膜的缺血再灌注损伤。     

Inflammatory markers in nondiabetic and diabetic rat retinas exposed to ischemia followed by reperfusion

PURPOSE: To examine the retinal inflammatory response to ischemia-reperfusion in nondiabetic and diabetic rats injected with either an omega-3-polyunsaturated fatty acid (docosahexaenoic acid [DHA]) or a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (pravastatin). METHODS: Diabetes was induced by an intraperitoneal injection of streptozocin, and retinal ischemia was induced by ligation of the optic nerve and vessels, followed by reperfusion for 1 hour or 24 hours. Five minutes before surgery, an intravenous injection of DHA, pravastatin, or vehicle (ethanol) was administered. The mRNA expressions of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, caspase-1, IL-1beta, P-selectin, vascular cellular adhesion molecule (VCAM)-1, and intercellular adhesion molecule (ICAM)-1 were compared between ischemic and nonischemic retinas as well as diabetic and nondiabetic nonischemic retinas. RESULTS: Ischemia induced increased expressions of TNF-alpha (P 相似文献