Diosmin protects rat retina from ischemia/reperfusion injury

Abstract Objective: Diosmin, a natural flavone glycoside, possesses antioxidant activity and has been used to alleviate ischemia/reperfusion (I/R) injury. The aim of this study was to clarify whether the administration of diosmin has a protective effect against I/R injury induced using the high intraocular pressure (IOP) model in rat retina, and to determine the possible antioxidant mechanisms involved. Methods: Retinal I/R injury was induced in the rats by elevating the IOP to 110?mmHg for 60?min. Diosmin (100?mg/kg) or vehicle solution was administered intragastrically 30?min before the onset of ischemia and then daily after I/R injury until the animals were sacrificed. The levels of malondialdehyde (MDA) and the activities of total-superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in the retinal tissues were determined 24?h after I/R injury. At 7 days post-I/R injury, electroretinograms (ERGs) were recorded, and the density of surviving retinal ganglion cells (RGCs) was estimated by counting retrograde tracer-labeled cells in whole-mounted retinas. Retinal histological changes were also examined and quantified using light microscopy. Results: Diosmin significantly decreased the MDA levels and increased the activities of T-SOD, GSH-Px, and CAT in the retina of rats compared with the ischemia group (P<0.05), and suppressed the I/R-induced reduction in the a- and b-wave amplitudes of the ERG (P<0.05). The thickness of the entire retina, inner nuclear layer, inner plexiform layer, and outer retinal layer and the number of cells in the ganglion cell layer were significantly less after I/R injury (P<0.05), and diosmin remarkably ameliorated these changes on retinal morphology. Diosmin also attenuated the I/R-induced loss of RGCs of the rat retina (P<0.05). Conclusion: Diosmin protected the retina from I/R injury, possibly via a mechanism involving the regulation of oxidative parameters.     

Protective effects of catalase on retinal ischemia/reperfusion injury in rats

Retinal ischemia/reperfusion (I/R) injury causes profound tissue damage, especially retinal ganglion cell (RGC) death. The aims of the study were to investigate whether catalase (CAT) has a neuroprotective effect on RGC after I/R injury in rats, and to determine the possible antioxidant mechanism. Wistar female rats were randonmized into four groups: normal control group (Control group), retinal I/R with vehicle group (I/R with vehicle group), retinal I/R with AAV-CAT group (I/R with AAV-CAT group), and normal retina with AAV-CAT group (normal with AAV-CAT group). One eye of each rat was pretreated with recombinant adeno-associated virus containing catalase gene (I/R with AAV-CAT group or normal with AAV-CAT group) and recombinant adeno-associated virus containing GFP gene (I/R with vehicle group) by intravitreal injection 21 days before initiation of I/R injury. Retinal I/R injury was induced by elevating intraocular pressure to 100 mmHg for 1 h. The number of RGC and inner plexiform layer (IPL) thickness were measured by fluorogold retrograde labeling and hematoxylin and eosin staining at 6 h, 24 h, 72 h and 5d after injury. Hydrogen peroxide (H₂O₂), the number of RGC, IPL thickness, malondialdehyde(MDA), 8-hydroxy-2-deoxyguanosine (8-OHdG), CAT activity and nitrotyrosine were measured by fluorescence staining, immunohistochemistry and enzyme-linked immunosorbent assay analysis at 5 days after injury. Electroretinographic (ERG) evaluation was also used. Pretreatment of AAV-CAT significantly decreased the levels of H₂O₂, MDA, 8-OHdG and nitrotyrosine, increased the catalase activity, and prevented the reduction of a- and b- waves in the I/R with AAV-CAT group compare with the I/R with vehicle group (p < 0.01). Catalase attenuated the I/R-induced damage of RGC and IPL and retinal function. Therefore, catalase can protect the rat retina from I/R-induced injury by enhancing the antioxidative ability and reducing oxidative stress, which suggests that catalase may be relevant for the neuroprotection of inner retina from I/R-related diseases.     

Protective effects of antithrombin III on retinal ischemia/reperfusion injury in rats: a histopathologic study

PURPOSE: To investigate the effect of antithrombin III (AT III) on retinal ischemia/reperfusion (I/R) injury in rats. METHODS: The study was carried out on 10 Wistar albino rats (20 eyes) and four-vessel occlusion method was employed to induce retinal ischemia in this study. Rats were divided into two groups: Group I (control group, 10 eyes) and Group II (AT III, 10 eyes). In both groups, vertebral arteries were occluded bilaterally an electric needle coagulator under an operating microscope. A total of 48 hours after the initial procedure, the rats were re-anesthetized and both common carotid arteries were clamped to interrupt blood flow. In Group II, rats were injected intravenously with 250 U/kg of AT III 5 minutes before the induction of ischemia. Duration of ischemia was 30 minutes. At the end of this period, clamp was removed for the reperfusion of the eye for 4 hours. Following the reperfusion period, the animals were killed by decapitation. Retinal sections were evaluated under light and electron microscope. The signs of I/R injury at the microscopic level, i.e., cellular degeneration, vacuolization between retinal layers, increase in the retinal thickness due to edema, mononuclear cell infiltration, and apoptotic cells, were recorded for each group. RESULTS: Retinal sections obtained from the rats in the AT III group revealed a well preserved retinal structure. When average thickness values of the two groups were compared to each other, the difference was significant with respect to inner nuclear and inner plexiform layers indicating increased retinal thickness values in Group I due to tissue edema resulting from I/R injury. Similarly, mononuclear cell infiltration and apoptotic cell counts were found to be significantly higher in control group compared to AT III group showing the inhibitory effect of AT III on leukocyte infiltration and apoptotic cell death in rat retina. CONCLUSIONS: Antithrombin III attenuated I/R injury in rat retina.     

Interleukin-6 in retinal ischemia reperfusion injury in rats

PURPOSE: To study the role of interleukin (IL)-6 after retinal ischemia-reperfusion (I/R) injury in rats. METHODS: Intraocular pressure of adult male Lewis albino rats was raised to create retinal ischemia for 1 hour. Retinal reperfusion was reestablished, and the animals were killed at various time points after the injury. Their eyes were enucleated and processed for immunohistochemistry to detect IL-6 and ED-1 (a marker of microglial/phagocytic cells), enzyme-linked immunosorbent assay (ELISA) of IL-6 protein, and semiquantitative real-time RT-PCR for IL-6 mRNA. The neuroprotective effect of IL-6 was evaluated by giving intravitreal injections of 150 or 300 ng rat recombinant IL-6 to eyes immediately after I/R injury and counting cresyl violet-stained retinal ganglion cell layer cells (RGCLCs) and fluorochrome-labeled retinal ganglion cells (RGCs) on flat preparations of retinas at 7 days. RESULTS: IL-6-positive cells appeared after I/R injury in the inner plexiform layer (IPL) and the inner nuclear layer (INL). Their numbers were significantly higher 18 hours after the injury, and most of these cells were also ED-1 positive. ELISA showed noticeable increases in endogenous retinal IL-6 protein levels 8 hours after I/R injury. Semiquantitative real-time RT-PCR showed significant increases in endogenous retinal IL-6 mRNA levels between 2 and 18 hours. Exogenously added IL-6 prevented between 50% and 70% of RGC loss after I/R injury. CONCLUSIONS: IL-6 is upregulated after retinal I/R injury, and its expression by microglia/phagocytic cells may protect RGC layer neurons from I/R injury. Exogenously added IL-6 protects the inner retina after I/R injury.     

Anti-inflammatory effects of lutein in retinal ischemic/hypoxic injury: in vivo and in vitro studies

Purpose. Lutein protects retinal neurons by its anti-oxidative and anti-apoptotic properties in ischemia/reperfusion (I/R) injury while its anti-inflammatory effects remain unknown. As Müller cells play a critical role in retinal inflammation, the effect of lutein on Müller cells was investigated in a murine model of I/R injury and a culture model of hypoxic damage. Methods. Unilateral retinal I/R was induced by a blockade of internal carotid artery using the intraluminal method in mice. Ischemia was maintained for 2 hours followed by 22 hours of reperfusion, during which either lutein (0.2 mg/kg) or vehicle was administered. Flash electroretinogram (flash ERG) and glial fibrillary acidic protein (GFAP) activation were assessed. Lutein's effect on Müller cells was further evaluated in immortalized rat Müller cells (rMC-1) challenged with cobalt chloride-induced hypoxia. Levels of IL-1β, cyclooxygenase-2 (Cox-2), TNFα, and nuclear factor-NF-kappa-B (NF-κB) were examined by Western blot analysis. Results. Lutein treatment minimized deterioration of b-wave/a-wave ratio and oscillatory potentials as well as inhibited up-regulation of GFAP in retinal I/R injury. In cultured Müller cells, lutein treatment increased cell viability and reduced level of nuclear NF-κB, IL-1β, and Cox-2, but not TNFα after hypoxic injury. Conclusions. Reduced gliosis in I/R retina was observed with lutein treatment, which may contribute to preserved retinal function. Less production of pro-inflammatory factors from Müller cells suggested an anti-inflammatory role of lutein in retinal ischemic/hypoxic injury. Together with our previous studies, our results suggest that lutein protected the retina from ischemic/hypoxic damage by its anti-oxidative, anti-apoptotic, and anti-inflammatory properties.     

Neuroprotective Effects of Granulocyte Colony-Stimulating Factor on Ischemia-Reperfusion Injury of the Retina

Purpose: It has been reported that granulocyte colony-stimulating factor (G-CSF) provides neuroprotection in models in which neuronal cell death is induced. This research was designed to investigate the effects of G-CSF on neurodegeneration of the inner retinal layer in a rat model of ischemic reperfusion (I/R) injury. Materials and Methods: Retinal ischemia was induced by increasing the intraocular pressure to 110 mm Hg for 45 min in the left eyes of the rats. A sham operation was carried out on the right eyes. G-CSF (100 μg/kg/day in 0.3 ml saline) or the same volume of saline was intraperitoneally injected just before the operation and continued for 4 consecutive days (a total of 5 consecutive days). Morphological examinations, including the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, were performed 7 days after I/R induction. The expression of phosphorylated AKT in the retina was examined by Western blot analysis and immunohistochemistry. Results: Cell loss in the ganglion cell layer was more significantly reduced in the I/R-induced eyes of the G-CSF-injected rats than in the I/R-induced eyes of the saline-injected rats (20.3 vs. 6.6%). The inner retinal thickness ratios, such as the inner plexiform layer to the inner limiting membrane/outer nuclear layer and the inner nuclear layer/outer nuclear layer, were significantly better preserved in the I/R-induced eyes of the G-CSF-injected rats than in the I/R-induced eyes of the saline-injected rats. TUNEL assays showed fewer apoptotic cells in the retinal sections of the I/R-induced eyes of the G-CSF-injected rats. The phosphorylation of AKT (p-AKT/AKT) was upregulated in the retinas of the I/R-induced eyes of the G-CSF-injected rats. Conclusion: Our results demonstrated that systemic injection of G-CSF can protect retinal ganglion cells and inner retinal layers from I/R injury. The effects could be associated with the activation of AKT.     

碘酸钠诱导兔视网膜色素上皮变性模型的研究

目的　通过静脉注射不同剂量的碘酸钠后观察兔视网膜色素上皮形态学及视网膜功能变化,以探索注射碘酸钠的合适剂量。方法　选取成年健康无眼病青紫兰兔３２只,随机分为对照组５只,实验１组（静脉注射碘酸钠１５ｍｇ·ｋｇ－１）、实验２组（静脉注射碘酸钠２５ｍｇ·ｋｇ－１）、实验３组（静脉注射碘酸钠３５ｍｇ·ｋｇ－１）各９只。对照组和实验组分别在耳缘静脉注射碘酸钠后１ｄ、３ｄ、７ｄ、１５ｄ、２８ｄ视网膜电图检查后处取视网膜后极部进行光镜及透射电镜观察。结果　实验２、３组诱导了兔视网膜色素上皮变性。实验２组:给药后３ｄ可见大量的视网膜色素上皮细胞自Ｂｒｕｃｈ膜上脱落,视细胞外节破坏,游离入感光细胞层;给药后７ｄ可见更严重的感光细胞破坏溶解,但外界膜完整;随时间推移;给药后２８ｄ外核层细胞数明显减少,视网膜成为无视网膜色素上皮或多层视网膜色素上皮相间结构。实验３组:给药后３ｄ即可见大量的视细胞内外节溶解坏死,外界膜、外核层受损。结论　静脉注射适当剂量的碘酸钠生理盐水能够选择性破坏视网膜色素上皮,成功造成视网膜色素上皮变性模型,２５ｍｇ·ｋｇ－１碘酸钠为合适剂量。     

Epigallocatechin-3-gallate reduces retinal ischemia/reperfusion injury by attenuating neuronal nitric oxide synthase expression and activity

Retinal ischemia/reperfusion (IR) injury causes profound tissue damage, especially retinal ganglion cell death. The aims of the study were twofold: (1) to investigate the benefits of epigallocatechin-3-gallate (EGCG), the major catechin found in tea, after IR challenge, and (2) to elucidate the mechanism of EGCG inhibition of nitric oxide synthase (NOS) expression. Wistar female rats were divided into four groups: normal control, EGCG with sham operation, retinal IR, and EGCG with IR groups. EGCG (50mg/kg) was administered by intraperitoneal injection 30 min before the experiment. IR injury to a rat's retina was induced by raising intraocular pressure to 150 mmHg for 60 min. With EGCG pretreatment, retinal ganglion cell death from IR was reduced by approximately 10% 3 days afterward. EGCG significantly downregulated IR-induced glial fibrillary acidic protein expression. EGCG treatment also reduced TUNEL-positive cells after IR in the inner retina as well as IR-induced lipid peroxidation. Histological analyses showed fewer neuronal NOS and nicotinamide adenine dinucleotide phosphate diaphorase-positive cells in the retina after IR with EGCG administration. Therefore, EGCG is effective in protecting retinal ganglion cells from IR challenge by ameliorating retinal nitrosactive stress and by regulating cell death through apoptotic pathways.     

Effect of trimetazidine on retinal ischemia/reperfusion injury in rats

PURPOSE: To investigate the effect of trimetazidine (TMZ), an antioxidant agent, on the ischemia/reperfusion (I/R) injury in rat retina histopathologically. METHODS: The retinal I/R model was carried out by the 4-vessel occlusion method on Wistar albino rats. Twenty-one rats were divided into 7 groups, each comprising 3 rats. The animals in groups 1, 2 and 3 underwent 30 min of ischemia + 4 h of reperfusion and were treated by the administration of saline, TMZ before reperfusion and TMZ before ischemia, respectively. The animals in groups 4, 5 and 6 underwent 90 min of ischemia + 4 h of reperfusion and were treated in the same way as those in groups 1, 2 and 3, respectively. The 7th group was sham operated. RESULTS: Thirty and 90 min of ischemia followed by 4 h of reperfusion induced retinal injury in the rat retina. Histopathologically, the inner plexiform and inner nuclear layers were the most affected parts. TMZ was able to reduce almost all retinal I/R damage when administered before ischemia. A cytoprotective effect of TMZ was partly observed in those animals which were treated before reperfusion. CONCLUSION: TMZ seemed to have a protective effect against retinal I/R injury in rats.     

大鼠视网膜缺血再灌注损伤后脑源性神经生长因子对细胞凋亡及caspase-2和caspase-3表达的影响

目的:探讨caspase-2和caspase-3在大鼠视网膜缺血再灌注损伤中的表达与细胞凋亡的关系及脑源性神经生长因子对其的影响及对视网膜的保护作用。方法:实验于2007-02/2007-07在青岛大学医学院附属医院中心实验室完成。前房加压法制作大鼠视网膜缺血再灌注损伤模型,28只大鼠随机分为正常组和手术组,其中手术组大鼠左眼为缺血再灌注组,右眼为治疗组(BDNF玻璃体腔注射),手术组又按照再灌注后不同时间段分为1,6,12,24,48,72h组。光学显微镜观察并计数视网膜神经节细胞的数量。应用末端脱氧核苷酸转移酶介导的脱氧尿苷三磷酸缺口末端标记法(TUNEL)检测视网膜神经节细胞凋亡、免疫组织化学法(SABC)和酶联免疫吸附实验(ELISA)检测视网膜组织中caspase-2和caspase-3的表达情况。结果:正常视网膜未见凋亡细胞表达,缺血后6～24h可见大量凋亡细胞表达,48h开始下降。凋亡细胞在缺血后24h达到高峰,caspase-2缺血6h后逐渐增加,24h达高峰,然后在48至72h下降。caspase-3表达改变与caspase-2改变基本一致。BDNF治疗组各观察指标表达变化规律与缺血组基本一致,但能明显抑制凋亡细胞的表达,同时使caspase-2和caspase-3的表达降低。结论:视网膜缺血再灌注损伤诱导了神经节细胞的凋亡;BDNF可抑制caspase-2和caspase-3的表达,减少神经节细胞凋亡,对视网膜缺血再灌注损伤有治疗作用。     

Neuroprotective effect of small interfering RNA targeted to caspase-3 on rat retinal ganglion cell loss induced by ischemia and reperfusion injury

Purpose: To investigate neuroprotective effects of siRNA targeted to caspase-3 against ischemia and reperfusion (I/R) injury in rat eyes. Methods: Retinal ischemia was induced in Wistar rats by increasing the intraocular pressure (IOP) to 110 mmHg for 120 min. To examine the effect of siRNA on rat caspase-3, siRNA was injected into the vitreous cavity 24 h prior to induction of retinal ischemia. Eyes were removed at 2, 7 or 14 days later, and then analyzed for the number of retinal ganglion cells (RGCs), the retinal thickness and the amount of apoptosis of the retinal neural cells (as demonstrated by the TUNEL assay). The amount of caspase-3 mRNA was analyzed by rt-PCR. Differences between groups were evaluated by an unpaired t test. Results: The numbers of RGCs in the saline and non-silencing siRNA controls were reduced significantly at 2 and 7 days after the I/R injury. RGCs were significantly retained in eyes pretreated with siRNA targeted to caspase-3 as compared to the control eyes at 2 days after the I/R injury. Inner retinal thickness in the control eyes was significantly thinner as compared to the treated eyes at 2 and 7 days after the I/R injury. After siRNA treatment, the amount of caspase-3 mRNA was significantly lower when compared to the saline control group. Conclusions: The injection of siRNA targeted to caspase-3 into the vitreous cavity of rat eyes may block caspase-3, and may thus be able to prevent retinal cell death associated with ischemic injury. As inhibition of the apoptosis pathway may provide a neuroprotective effect, examination of new strategies for treating these disorders needs to be undertaken.     

小鼠视网膜缺血-再灌注后核因子-κB的激活

目的 研究小鼠视网膜缺血-再灌注所致视网膜神经细胞凋亡中,核因子-κB的表达。方法 通过升高小鼠眼内压造成视网膜缺血,用计算机图像分析方法测量视网膜再灌注后神经细胞凋亡的比例和视网膜厚度的改变。免疫组化标记核因子-κB p65亚单位,并与原位缺口末端标记（TUNEL）做双重荧光标记,分析核因子-κB的表达与细胞凋亡之间的时相关系。结果 视网膜缺血-再灌注后最初24h,视网膜内层厚度增加,至168h,厚度显著减少。再灌注后6h,神经节细胞和内核细胞层中p65的免疫表达增强,至24h达到高峰,这一过程与TUNEL标记的时相一致。结论 视网膜缺血-再灌注损伤后,核因子-κB的激活对于视网膜神经细胞的凋亡有重要作用,对于其起促进凋亡还是抑制凋亡的作用,则有待于进一步研究。     

Activation of the aldosterone/mineralocorticoid receptor system and protective effects of mineralocorticoid receptor antagonism in retinal ischemia-reperfusion injury

The purpose of this project was to investigate the effects of the mineralocorticoid receptor antagonist against retinal ischemia-reperfusion injury and identify the aldosterone/mineralocorticoid receptor (MR) system in the rat retina. Retinal ischemia was induced by increasing intraocular pressure to 130?mmHg. Rats were treated with the angiotensin II type 1 receptor (AT1-R) antagonist (candesartan), MR antagonist (spironolactone), or aldosterone. Retinal damage was evaluated at 7 days after the ischemia by measuring the retinal thickness and the number of retinal ganglion cells. Pretreatment with candesartan, spironolactone, or candesartan and spironolactone significantly inhibited retinal ischemic injury. However, there was no protective effect against retinal ischemia-reperfusion injury provided by the combined aldosterone with candesartan treatment. Additionally, pretreatment with aldosterone alone also did not provide any neuroprotective effects against retinal ischemia-reperfusion injury. When rats were treated via local administration of aldosterone in the absence of ischemia, the number of retinal ganglion cells decreased while the retinal thickness remained unchanged. The present findings demonstrated the existence of a local aldosterone/MR system in the retina. Our results also demonstrated that an MR antagonist can attenuate subsequent ischemic damage in the rat retina.     

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.     

Protective effect of trimetazidine in a model of ischemia-reperfusion in the rat retina

Trimetazidine is an anti-ischemic agent which is frequently prescribed as a prophylactic treatment of episodes of angina pectoris and as a symptomatic treatment of vertigo and tinnitus. It has also shown beneficial effects in models of visual dysfunction, but the mechanism(s) by which this occurs is as yet undefined. The present study was intended to evaluate the influence of trimetazidine on retinal damage induced by ischemia-reperfusion in a rat model. Retinal ischemia was induced by increasing intraocular pressure to 160 mm Hg for 60 min. Trimetazidine or buffer controls were administered 3 days before the ischemia or in the postischemic period. The degree of retinal damage was assessed after 15 and 30 days of reperfusion after the ischemic insult by histopathologic study according to Hughes' quantification of ischemic damage. Retinal ischemia led to significant reductions in thickness and cell number, mainly in the inner retinal layers. The results from the study demonstrate that treatment with intraperitoneally injected trimetazidine conferred significant protection against retinal ischemic damage. Better results were obtained in the pretreatment group after 15 days of reperfusion. Trimetazidine protects the rat retina from pressure-induced ischemic injury and might be considered a potential therapeutic modality for combating retinal ischemia.     

色素上皮衍生因子对大鼠视网膜缺血 再灌注损伤的保护作用

目的已证实色素上皮衍生因子(pigment epithelium-deriv ed factor,PEDF)对中枢神经细胞有抗凋亡作用。本实验评价其对压力诱发的视网膜缺血再灌注的影响。方法经前房灌注维持眼压110 mm Hg (1 mm Hg = 0.133kpa),45 min,建立大鼠视网膜缺血再灌注模型。 随后立即向玻璃体注射10　μ1(0.1μg/μl)PEDF,分别于2d和7d摘除眼球,测量塑 料包埋切片的平均视网膜内层厚度(mean thickness of inner retinal layer,MTIRL) 和视网膜节细胞(retinal ganglion cells,RGC)计数。结果PEDF玻璃体注射7d后治疗组的MTIRL和RGC明显高于对照组[(118.1±5．0) μm对(949±3.0)μm, P<0.05;(6.0±1．0)个/100 μm对(4.5±0.5)个/100 μm, P<0.05]。结论玻璃体内注射PEDF有助于防止视网膜缺血再灌注后神经变性和细胞死亡。(中华眼底病杂志,2001,17:138-140)     

Hydrogen-rich saline protects retina against glutamate-induced excitotoxic injury in guinea pig

Molecular hydrogen (H(2)) is an efficient antioxidant that can selectively reduce hydroxyl radicals and inhibit oxidative stress-induced injuries. We investigated the protective effects and mechanism of hydrogen-rich saline in a glutamate-induced retinal injury model. Retinal excitotoxicity was induced in healthy guinea pigs by injecting glutamate into the vitreous cavity. After 30?min, hydrogen-rich saline was injected into the vitreous cavity, the peritoneal cavity or both. Seven days later, the retinal stress response was evaluated by examining the stress biomarkers, inducible nitric-oxide synthase (iNOS) and glucose-regulated protein 78 (GRP78). The impaired glutamate uptake was assessed by the expression of the excitatory amino acid transporter 1(EAAT-1). The retinal histopathological changes were investigated, focusing on the thicknesses of the entire retina and its inner layer, the number of cells in the retinal ganglion cell layer (GCL) and the ultrastructure of the retinal ganglion cells (RGCs) and glial cells. Compared with the glutamate-induced injury group, the hydrogen-rich saline treatment reduced the loss of cells in the GCL and thinning of the retina and attenuated cellular morphological damage. These improvements were greatest in animals that received H(2) injections into both the vitreous and the peritoneal cavities. The hydrogen-rich saline also inhibited the expression of glial fibrillary acidic protein (GFAP) in Müller cells, CD11b in microglia, and iNOS and GRP78 in glial cells. Moreover, the hydrogen-rich saline increased the expression of EAAT-1. In conclusion, the administration of hydrogen-rich saline through the intravitreal or/and intraperitoneal routes could reduce the retinal excitotoxic injury and promote retinal recovery. This result likely occurs by inhibiting the activation of glial cells, decreasing the production of the iNOS and GRP78 and promoting glutamate clearance.     

The protective effects of melatonin,vitamin E and octreotide on retinal edema during ischemia-reperfusion in the guinea pig retina

PURPOSE: The purpose of this study is to provide evidence that free radical damage is a component of retinal ischemia-reperfusion (I/R) injury, and to determine whether melatonin, vitamin E and octreotide can protect retina from this injury. METHODS: The right eyes of 50 male guinea pigs weighing 500-600 g were used. The animals were randomly assigned to group 1 (control), group 2 (I/R), group 3 (melatonin + I/R), group 4 (vitamin E + I/R) and group 5 (octreotide + I/R). Groups 3, 4 and 5 received four subcutaneous injections at six-hour intervals for total dosage of 10 mg/kg melatonin, 150 mg/kg vitamin E and 22 microg/kg octreotide respectively. The first dose of each substance was administered 5 minutes before retinal ischemia. Retinal ischemia was induced for 1.5 hours, then followed by reperfusion for 24 hours. Infections of all three substances were repeated at 6, 12 and 18 hours during reperfusion. The animals were killed at 24 hours of reperfusion. Sagittal sections of 4 microm were cut and stained with hematoxylin and eosin for light microscopic evaluation. The average thickness (edema) of the inner plexiform layer for each eye was measured in sagittal sections near the optic nerve and expressed in microns. RESULTS: The efficacy of each compound had the following relationships: melatonin>vitamin E>octreotide in preventing retinal damage by ischemia-reperfusion. The mean thickness of the inner plexiform layer was 13.3 +/- 0.8 microm, 25.9 +/- 2. 0 microm, 20.0 +/- 0. 7 microm, 21.6 +/- 0.7 microm, 23.9 +/- 0.8 microm respectively in the control, I/R, I/R plus melatonin, I/R plus vitamin E and I/R plus octreotide groups. The thickness of the inner plexiform layer in group 1 (control) was significantly less than the other groups (p<0.001). The inner plexiform layer was thicker in the I/R group than with I/R plus melatonin, I/R plus vitamin E and I/R plus octreotide (all p < 0.01). The inner plexiform layer was thicker in the I/R plus octreotide group than the I/R plus vitamin E and I.R plus melatonin groups both (p < 0.05). Compared to the I/R plus melatonin group, the inner plexiform layer was significantly thicker in the I/R plus vitamin E group (p < 0. 05). CONCLUSIONS: This study demonstrates a protective effect of melatonin, vitamin E and octreotide on the retina during retinal ischemia-reperfusion injury.