L-carnitine in experimental retinal ischemia-reperfusion injury

The effect of L-carnitine on retinal ischemia-reperfusion injury was evaluated in guinea pigs. 90 min of pressure-induced retinal ischemia followed by 24 h of reperfusion was established in both eyes of 2 groups of animals receiving either L-carnitine (100 mg/kg repeated in 5 doses) or saline intraperitoneally. After enucleation of all the eyes, including those of a control group, malonyldialdehyde (MDA) levels and the thickness of the retinal tissue were measured in 3 groups. The mean MDA value and the tissue thickness of the L-carnitine-treated group were statistically insignificant versus the control group (p > 0.05 and p > 0.05, respectively). However, these values were significantly different in the group receiving saline versus the control group and that receiving L-carnitine (p < 0.001, p < 0.001 and p < 0.001, p < 0.001 respectively). L-Carnitine might be an alternative drug for ischemia-reperfusion injury of the retina.     

视网膜缺血--再灌注损伤的保护

视网膜缺血-再灌注损伤是目前研究较多的一个课题,其损伤机制复杂,目前通过各种实验研究探索其损伤机制以及减轻或防止缺血-再灌注损伤的药物和方法很多.现就视网膜缺血-再灌注损伤的保护机制进行总结归纳.     

Caspase-7与视网膜缺血-再灌注损伤

视网膜缺血-再灌注损伤是细胞凋亡、炎症反应等多种机制参与的病理生理过程。半胱氨酸蛋白酶７（Ｃａｓｐａｓｅ-７）是Ｃａｓｐａｓｅ家族中的凋亡效应分子,近期研究表明,它在调控炎症细胞因子方面也起着重要作用。本文就Ｃａｓｐａｓｅ-７生物学特性及其与细胞凋亡、炎症反应在视网膜缺血-再灌注损伤的分子机制进行综述。     

一氧化氮与视网膜缺血-再灌注损伤

一氧化氮（NO）在视网膜缺血-再灌注损伤中占重要地位。视网膜缺血-再灌注时,一氧化氮合成酶（NOS）被多种炎性介质和细胞因子激活,使NO大量生成。NO是一种活性很强的自由基,具有广泛的生物学活性。在缺血-再灌注早期,少量NO可降低缺血缺氧对视网膜的损伤程度;晚期过多的NO可通过多种途径对视网膜造成损害。就目前有关NO在视网膜缺血-再灌注损伤中的研究进展进行综述。     

自由基与视网膜缺血-再灌注损伤

自由基在视网膜缺血-再灌注损伤中占有重要地位。视网膜缺血-再灌注时黄嘌呤氧化酶（XO）增加，花生四烯酸代谢系统环氧化旁路，线粒体功能障碍，一氧化氮合成酶（NOS）激活及中性粒细胞系统被激活，使自由基生成大大增加。体内清除自由基的酶系统和抗氧化剂不足以清除生成的自由基而引起脂质，蛋白质和核酸等生物大分子的氧化损伤。给予外源性的自由基清除剂和抗氧化酶等通过加速自由基清除或抑制自由基生成而减轻视网膜缺血-再灌注损伤。     

视网膜缺血再灌注损伤中谷氨酸的兴奋毒性及其机制

视网膜缺血再灌注(retinal ischemia reperfusion,RIR)损伤是多因素综合作用的结果,兴奋性氨基酸学说是其机制之一。谷氨酸本是一种主要的神经兴奋递质,行使重要的生理功能,而RIR过程中,细胞间质内谷氨酸浓度明显升高,过度激活谷氨酸受体,引起兴奋毒性,其机制主要有钙离子超载、过多一氧化氮合成、细胞内氧自由基升高及细胞凋亡等方面。     

视网膜缺血再灌注损伤的治疗进展

视网膜缺血再灌注损伤是目前临床上常见的眼病,主要发生于视网膜中央动静脉栓塞、急性闭角性青光眼、糖尿病性视网膜病等视网膜血管阻塞所引起的缺血性眼病.表现为许多缺血性眼病患者在血液再通后,视网膜损伤严重,视功能反而进一步下降.视网膜缺血再灌注损伤是多因素综合作用的结果,主要包括氧自由基的损伤作用,细胞内的钙超载现象,白细胞作用以及细胞凋亡等.本文就国内外有关视网膜缺血再灌注损伤的治疗进展综述如下.     

Nitric oxide and octreotide in retinal ischemia-reperfusion injury

This experimental study was performed to investigate the role of ischemia–reperfusion injury on retinal nitric oxide activity and to determine whether octreotide, the synthetic analogue of natural somatostatin, modifies the nitric oxide activity during retinal ischemia–reperfusion in a quinea pig model. Three groups of seven pigmented male quinea pigs were formed; Control, Ischemia and the Ischemia/Octreotide groups. 90 minutes of pressure-induced retinal ischemia and 24 h of reperfusion were established in the ischemia and ischemia/octreotide groups. Saline for the ischemia group and 50 g/kg of octreotide for the ischemia/octreotide group were administered intraperitoneally five times with 6-h intervals. At the end of the reperfusion period both eyes of the animals of the three groups were enucleated. One eye of each animal was randomly selected for biochemical assay and the other for histopathological analysis. Retinal nitrate levels were measured and histopathological changes were evaluated in the groups. The mean retinal nitrate levels of the control, ischemia and ischemia/octreotide groups were 157.6±25.2, 106.4±20.1 and 96.4±17.7 mol/l, respectively. Nitrate levels decreased significantly both in the ischemia (p<0.01) and ischemia/octreotide (p<0.01) groups versus control. In the ischemia group, retinal histopathological changes, which were different from the control group, were prominent edema, polymorphonucleated leukocytes infiltration and vacuolated spaces in the inner retina. No significant change was observed in the histopathological specimens of the ischemia/octreotide group. Significant increase in the thickness of the inner plexiform layer of the retina of the ischemia group was observed versus the control and ischemia/octreotide groups (p<0.01 and p<0.01, respectively).The thickness of the inner plexiform layer of the retina of the ischemia/octreotide group did not change versus the control group. It was concluded that nitric oxide activity decreased during retinal ischemia–reperfusion and, although octreotide prevented the histopathological damage, it could not ameliorate the nitric oxide activity of the retina.This study was presented in part at the 23rd Congress of the European Society of Ophthalmology.     

Lipid peroxidation and peroxynitrite in retinal ischemia-reperfusion injury

PURPOSE: To investigate whether lipid peroxides play a role in retinal cell death due to ischemia-reperfusion injury, whether recombinant human thioredoxin (rhTRX) treatment reduces production of lipid peroxides of the retina, and whether such treatment reduces the number of cells expressing c-Jun and cyclin D1. METHODS: Retinal ischemia was induced in rats by increasing the intraocular pressure to 110 mm Hg for 60 minutes. After reperfusion, immunohistochemical staining for lipid peroxide, peroxynitrite, c-Jun, and cyclin D1 and propidium iodide (PI) staining were performed on retinal sections from animals treated intravenously with and without rhTRX, a free radical scavenger. Quantitative analyses of PI-, c-Jun-, and cyclin D1-positive cells were performed after the ischemic insult. Concentration of lipid peroxides in the retina was determined by the thiobarbituric acid assay. RESULTS: Specific immunostaining for lipid peroxides was seen in the ganglion cell layer at 6 hours after reperfusion, in the inner nuclear layer at 12 hours, and in the outer nuclear layer at 48 hours. Time course studies for PI-positive cells in the three nuclear layers coincided with those of specific immunostaining for lipid peroxides. The specific immunostaining was weakened by pre- and posttreatment with 0.5 mg of rhTRX. The number of PI-, c-Jun-, and cyclin D1-positive cells and the concentration of lipid peroxides were significantly decreased by treatment with rhTRX compared with those of vehicle-treated control rats (P: < 0. 01). CONCLUSIONS: Lipid peroxides formed by free radicals may play a role in neuronal cell death in retinal ischemia-reperfusion injury.     

Neuroprotective effects of D-allose against retinal ischemia-reperfusion injury

PURPOSE: To investigate the effect of D-allose, a rare sugar, against ischemia reperfusion injury in the rat retina. METHODS: Retinal ischemia was induced by increasing intraocular pressure to 130 mm Hg and maintaining that level for 45 minutes. Morphometric studies were performed to study the effect of D-allose on the histologic changes induced by ischemia in the rat retina. Glutamate release from the rat retina and intravitreal P(O2) profiles were monitored during and after ischemia with a microdialysis biosensor and oxygen-sensitive microelectrodes. The release of hydrogen peroxide stained with diaminobenzidine hydrochloride was monitored by an in vitro retinal ischemia model. RESULTS: Seven days after the ischemia, significant reductions in both the number of ganglion cells and the thickness of the inner plexiform layer were observed. Pretreatment with D-allose significantly inhibited the ischemic injury of the inner retina. A large release of glutamate occurred during the ischemia. After the recirculation, glutamate levels were increased again and reached a maximum in approximately 20 minutes. The increases in extracellular glutamate during and after ischemia tend to be suppressed by administration of d-allose. d-Allose attenuated the increase in intravitreal P(O2) during reperfusion. After the ischemia, production of hydrogen peroxide was detected within approximately 30 minutes. D-allose suppressed the production of hydrogen peroxide. CONCLUSIONS: These results suggest that D-allose may protect neurons by decreasing extracellular glutamate and attenuating oxidative stress in ischemic insult.     

牛磺酸对大鼠视网膜缺血再灌注损伤的影响

目的观察牛磺酸对大鼠视网膜缺血再灌注损伤的影响及其作用机制。方法将90只SD大鼠随机分为3组:对照组、缺血组和保护组,采用前房灌注液体形成14.63kPa高眼压1h的方法,建立缺血再灌注模型。保护组连续3d每天2次腹腔注射100g.L-1的牛磺酸,剂量为100mg.kg-1,于术前30min加注1次。缺血组、对照组给予同等剂量的生理盐水。缺血组和保护组2组缺血60min后,分别再灌注0h、2h、6h、12h、24h、48h、72h,比色法测定视网膜超氧化物歧化配备酶、丙二醛、一氧化氮,光镜测量包埋切片的平均视网膜内层厚度。结果牛磺酸能显著对抗大鼠视网膜缺血再灌注后丙二醛和一氧化氮水平的升高,同时能改善平均视网膜内层厚度的变化,但对超氧化物歧化酶的作用不确定。结论牛磺酸可减轻大鼠视网膜缺血再灌注后的损伤。     

Nogo-A和NgR在大鼠视网膜缺血再灌注损伤中的表达

目的：观察轴突生长抑制因子Nogo-A及其受体NgR在视网膜缺血再灌注（retinal ischemia-reperfusion,RIR）急性损伤中的表达,研究两者在RIR损伤中的作用及相关性。 方法：SD大鼠90只随机分为：正常对照组（n=6）;假手术组(n=42);RIR组（n=42）,假手术组及RIR组分为再灌注后0,6,12,24,48,72,168h亚组,每组6只;采用结扎单侧颈总动脉的方法制备大鼠RIR模型,HE染色观察组织形态学改变,免疫组织化学检测Nogo-A和NgR蛋白的表达。 结果：假手术组各时间点Nogo-A及NgR表达与正常组相比无统计学差异（P>0.05）,实验组大鼠与假手术组相比：Nogo-A的表达在12h开始升高（P<0.05）,48h达到高峰（P<0.01）,72h下降（P<0.05）,168h达到正常基线水平（P>0.05）;NgR的表达在6h即出现上升,持续至48h达到最高峰（P<0.01）,72h下降,168h达到正常基线水平。实验组大鼠Nogo-A与NgR的表达呈正相关（P<0.01）。 结论：Nogo-A和NgR在RIR各时间点均有表达,其表达水平沿时间点呈抛物线形,在再灌注48h时均达到峰值,NgR先于Nogo-A表达,两者协同作用,与RIR损伤后抑制节细胞轴突修复再生有关。     

金雀异黄酮对大鼠视网膜缺血-再灌注损伤的保护作用

目的 探讨金雀异黄酮(GEN)对大鼠视网膜缺血-再灌注(L/R)损伤的保护作用.方法 选取30只健康SPF级大鼠,按照随机数字表法将其分为假手术组、I/R组和L/R+ GEN组,每组各10只.I/R组和I/R+ GEN组大鼠采用前房灌注生理盐水升高眼压法制备视网膜I/R损伤大鼠模型,I/R组大鼠术后每天给予注射生理盐水...     

藏红花素对大鼠视网膜缺血-再灌注损伤的保护作用

目的　观察大鼠视网膜缺血-再灌注损伤（retinal ischemia-reperfusion injury，RIRI）时藏红花素对视网膜细胞凋亡数目、凋亡相关蛋白Caspase-3表达的影响，探讨缺血再灌注时藏红花素对视网膜的保护作用机制。方法　选取体质量200~250 g的健康雄性SD大鼠24只，随机分为4组:对照组、模型组、藏红花素低剂量组和藏红花素高剂量组，每组6只。藏红花素低剂量组、高剂量组分别于造模前3 d、30 min定时腹腔注射5 g·L^-1藏红花素5 mg·kg^-1、50 mg·kg^-1。造模成功后24 h处死大鼠并摘取眼球。使用电镜观察各组大鼠视网膜细胞结构，TUNEL染色检测视网膜凋亡细胞数量，免疫组织化学染色法观察凋亡相关蛋白Caspase-3在视网膜中的表达。结果　视网膜TUNEL染色发现，对照组视网膜组织中几乎未发现凋亡细胞的阳性表达，模型组视网膜神经节细胞层和内核层中发现大量棕黄色着色的细胞，其凋亡细胞数为（27.40±0.96）个，藏红花素低剂量组可见神经节细胞层、内核层凋亡细胞数较模型组减少，凋亡细胞数为（8.40±0.41）个，与模型组相比差异有统计学意义（P<0.01）；藏红花素高剂量组凋亡细胞数较模型组和低剂量组明显减少，凋亡细胞数为（4.30±0.47）个，和藏红花素低剂量组相比差异有统计学意义（P<0.01）。对照组大鼠视网膜组织Caspase-3染色阴性，模型组视网膜神经节细胞层可见棕黄色颗粒位于细胞浆内，藏红花素低剂量组Caspase-3蛋白表达量与模型组类似，藏红花素高剂量组Caspase-3蛋白表达量与对照组类似。结论　藏红花素能通过降低Caspase-3蛋白含量及凋亡细胞数，从而有效保护视网膜免受RIRI。     

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.     

Agmatine as retinal protection from ischemia-reperfusion injury in guinea pigs

Purpose  To determine the neuroprotective effect of agmatine (Agm) on the retinas of guinea pigs subjected to a transient ischemia-reperfusion insult. Methods  Twenty-eight guinea pigs were randomly divided into four groups. Forty-five minutes before ischemic insult, the guinea pigs were intraperitoneally administered either Agm (50 mg/kg) (Agm 1) or saline (control 1 group) once, or twice separated by a 12-h interval (Agm 2; control 2). Transient ocular ischemia was achieved under general anesthesia by cannulating an anterior chamber maintainer connected to an infusion line of a semiflexible bottle. The saline reservoir pressure was increased by using a blood pressure tolls cuff to achieve an intraocular pressure (IOP) of 150 mmHg. This IOP was maintained for 90 min. Reperfusion was achieved by pulling off the anterior chamber maintainer. The animals in the Agm 1 and control 1 groups were killed at the end of the 4-h reperfusion period. The eyes were enucleated for histopathological (retinal thickness) and biochemical (thiobarbituric acid reactive substance, TBARS, and nitric oxide, NO) investigation. The animals in the Agm 2 and control 2 groups were killed at the end of a 24-h reperfusion period. Results  The mean retinal thickness of the animals in the Agm 1 (25.94 ± 1.23 μm) and Agm 2 (24.49 ± 0.88 μm) groups was lower than that of those in the control 1 (37.60 ± 2.27 μm) and control 2 (36. 64 ± 1.32 μm) groups (P < 0.05). The mean TBARS level of the animals in the Agm 1 (8.37 ± 0.94 nmol/ml) and Agm 2 (8.01 ± 0.97 nmol/ml) groups was lower than that of those in the control 1 (12.09 ± 1.27 nmol/ml) and control 2 (12.09 ± 1.27 and 11.72 ± 1.63 nmol/ml) groups (P < 0.05). The mean NO level of the animals in the Agm 1 (100.77 ± 6.20 nmol/ml) and Agm 2 (94.63 ± 5.24 nmol/ml) was lower than that of those in the control 1 (131.77 ± 4.61 nmol/ml) and control 2 (122.43 ± 4.35 nmol/ml) groups (P < 0.05). There were positive correlations between the TBARS and NO levels and retinal thickness in the Agm and control groups. Conclusion  Agmatine exerts a significant neuroprotective effect on guinea pig retinas after transient ischemia-reperfusion insult.     

GM-1对大鼠视网膜缺血再灌注损伤的保护作用

目的 探讨单唾液酸神经节苷脂（monosialoganglioside,GM-1）对大鼠视网膜缺血冉灌注损伤后视网膜组织及超微结构的保护作用.方法 健康成年Wistar大鼠75只,随机分为3组：正常组5只、NS组35只,GM-1组35只.正常对照组不加任何处理因素,NS组和GM-1组通过升高眼压造成视网膜缺血60 min,分别于缺血前12 h、1 h及缺血结束时3次腹腔注射NS 3mL/kg或GM-1 3mL/kg（10 mg/mL）,并于再灌注0 h（单纯缺血后）、1 h、6 h、12 h、24 h、3 d和7 d共7个时间点取双眼眼球,每时间点5只,HE染色观察视网膜组织结构并测量视网膜内层平均厚度（mean thickhess of the inner retinal layers,MTIRL）,透射电镜观察视网膜超微结构变化.结果 缺血再灌注后,内层视网膜依次表现出水肿、凋亡、萎缩的损伤过程.GM-1可明显减轻其水肿和萎缩的程度,并减少凋亡的发生.结论 GM-1对视网膜缺血再灌注损伤具有明确的保护作用,可能是其有效治疗药物.     

牡荆苷对大鼠视网膜缺血-再灌注损伤模型中神经节细胞的保护作用

目的:探讨牡荆苷对大鼠视网膜缺血-再灌注(RIR)引起的视网膜神经节细胞(RGCs)氧化应激损伤的保护作用及其可能的作用机制。方法:将60只SPF级雄性SD大鼠按照随机数字表法随机分为正常对照组、模型组和牡荆苷组,均以右眼为实验眼。模型组和牡荆苷组大鼠采用前房灌注方法建立RIR模型,牡荆苷组大鼠建模后每日按照25 mg...     

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.