补阳还五汤对大鼠视网膜缺血再灌注损伤的作用

目的:观察补阳还五汤(Buyang Huanwu Decoction,BYH-WT)对Wistar大鼠视网膜、视神经缺血再灌注损伤是否具有保护作用,并进一步探讨补阳还五汤的作用机理。方法:使用Wistar大鼠建立视网膜、视神经缺血再灌注损伤模型。模型建立后,将大鼠随机分为2组:(1)中药组:缺血60min后开始灌服BYHWT水煎剂[10g/(kg·d)];(2)对照组:缺血60min后开始灌服平衡盐液[10g/(kg.d)]。两组分别在灌服后24h、6wk取材行视网膜和视神经的超微结构观察。结果:中药组24h和对照组的视网膜及视神经的超微结构均有明显病变,但中药组较对照组变化轻微。中药组6wk的视网膜及视神经的病变基本恢复正常;对照组仍存明显病变。结论:补阳还五汤对大鼠视网膜、视神经缺血再灌注损伤具有保护作用。     

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.     

葛根素对实验性视网膜缺血-再灌注损伤后视神经的保护作用

目的探讨葛根素对实验性高眼压视网膜缺血-再灌注损伤后视神经的保护作用及其机制。方法用眼内灌注法前房灌注林格氏液制成急性高眼压视网膜缺血-再灌注损伤模型。将70只SD大鼠随机分为正常对照组(10只),葛根素治疗组(30只)和模型组(30只)。其中后2组根据再灌注的时间不同分为1d、3d、7d组,每组10只大鼠。治疗组经大鼠腹腔注射葛根素注射液(60mg·kg-1),模型组经大鼠腹腔注射生理盐水(10mL·kg-1)。利用免疫组织化学法检测各组大鼠视网膜内一氧化氮合酶(neural nitrogenoxide synthase,nNOS)的表达,以及硫代巴比妥酸法测量丙二醛(malonaldialdehyde,MDA)含量,黄嘌呤氧化酶法测超氧化物歧化酶(superoxide dismutase,SOD)活性。结果从再灌注1d开始,模型组视网膜内nNOS阳性表达明显增多,MDA水平持续升高,SOD活性持续下降,其差异与正常对照组相比,有统计学意义(P<0.01)。与模型组相比,再灌注各时段葛根素治疗组nNOS阳性神经元明显减少(P<0.01),MDA含量降低(P<0.01),SOD活性升高(P<0.01),其中nNOS阳性神经元与正常对照组相比,无统计学意义(P>0.05)。结论葛根素可通过提高视网膜组织中SOD活性,降低MDA含量,以及增加组织中nNOS表达,对大鼠实验性高眼压视网膜缺血-再灌注损伤有一定的保护作用。     

倍他洛尔对实验性视网膜缺血再灌注损伤后 视神经的保护作用

目的探讨倍他洛尔对实验性视网膜缺血再灌注损伤后视神经的保护作用及其可能的作用机制。方法采用升高眼内压的方法，制作大鼠实验性视网膜缺血再灌注损伤模型。将68只SD大鼠随机分为正常对照组（8只）、0.25%倍他洛尔治疗组（30只）和生理盐水对照组（30只）。其中后两组根据再灌注的不同时间各分为1、3、7 d组，每组10只大鼠。治疗组鼠右眼滴入0.25%倍他洛尔眼药水，生理盐水对照组鼠右眼滴入生理盐水。观察治疗组和生理盐水对照组及正常对照组鼠视网膜电图（ERG）b波振幅及光学显微镜、电子显微镜下视网膜结构变化；免疫组织化学法检测神经性一氧化氮合酶（nNOS）的表达,分光光度法测定丙二醛(MDA)含量及超氧化物歧化酶(SOD)活性。结果从再灌注1 d开始，生理盐水对照组ERG的b波振幅持续下降，病理组织损害逐渐加重，视网膜中nNOS阳性表达明显增多，MDA水平持续升高，SOD水平持续下降，其差异与正常对照组比较均有统计学意义（P＜0.01）；与生理盐水对照组相比，再灌注各时段倍他洛尔治疗组ERG的 b波振幅明显恢复（P＜0.01），病理组织损害明显减轻，nNOS阳性神经元明显减少（P＜0.01），MDA含量降低（P＜0.01），SOD活性升高（P＜0.01），其中nNOS阳性神经元与正常对照组的差异无统计学意义（P＞0.05）。结论倍他洛尔可能通过减少细胞内Ca²⁺超载，抑制NO的产生和提高抗氧化能力，对大鼠实验性视网膜缺血再灌注损伤有一定的保护作用。(中华眼底病杂志,2005,21:249-252)      

MMP-9、TIMP-1在大鼠视网膜缺血-再灌注损伤中的表达

目的 探讨高眼压视网膜缺血-再灌注(retina ischemia-reperfusion，RIR)损伤时大鼠视网膜基质金属蛋白酶9(matrix metalloproteinase 9，MMP-9)和组织金属蛋白酶抑制剂1(tissue inhibitor of metalloproteinase 1，TIMP-1)的动态变化及意义。方法 利用前房高压灌注法造成大鼠视网膜缺血1h，再恢复其供血，并于再灌注0h、3h、12h、24h、48h和72h后处死，采用免疫组化SP法和计算机图像分析系统检测视网膜MMP-9和TIMP-1的表达和分布。结果 RIR 0h视网膜MMP-9表达极弱，MMP-9阳性染色于RIR3h出现，12h迅速增加，24h达高峰，以后逐渐下降，72h接近正常。RIR各时段TIMP-1水平无明显改变。结论 MMP-9是参与RIR损伤的重要因素．     

Expression of matrix metalloproteinases and their inhibitors in experimental retinal ischemia-reperfusion injury in rats

Matrix metalloproteinases (MMPs) are endopeptidases that degrade the extracellular matrix (ECM) and are involved in the pathogenesis of retinal degeneration along with tissue inhibitors of metalloproteinases (TIMPs). The present study examined the expression and activation of two specific members of MMPs (MMP-2 and MMP-9) and their related inhibitors (TIMP-1 and TIMP-2) in an experimental retinal ischemia-reperfusion injury. Retinal ischemia-reperfusion injury (RIRI) was induced in adult rats with a ligation method. After one hour of ischemia and a varied reperfusion time (0, 3, 6, 12, 24, 48 and 76 hr), the rat eyes were enucleated. Retinal extracts underwent zymographic analysis to measure the activity of MMP-2/9. The activity of TIMP-1 and TIMP-2 was measured by reverse zymography. The protein level was examined by Western blot. Immunohistochemistry analysis was undertaken to assess the anatomical distribution of MMP-9 in the retina after RIRI. The gelatinolytic activity of ProMMP-2 (72 kDa) was increased markedly at 6 hr after RIRI. ProMMP-9 (92 kDa) was not detected in the control specimens, while it appeared at 3 hr, increased markedly at 6 hr, and reached maximal levels at 24 hr after RIRI. The gelatinolytic activity found ian retinal extracts was shown to be inhibited by 10 m M EDTA and activated in vitro by a known metalloproteinase activator (4-aminophenylmercuric acetate (APMA)), indicating that these enzymes were of the metalloproteinase class. By western blot, MMP-2/9 levels increased parallel to protein activity level in zymography. No corresponding increase in TIMP-1 and TIMP-2 protein activity and protein level was detected by reverse zymography and western blot. Elevated levels of MMP-9 and its distribution in retina were confirmed by immunohistochemistry. Expression of MMP-9 was detected in the inner and outer segments of rat retina, and the level becomes stronger at 24 hr after RIRI. In this study, ProMMP-2 and ProMMP-9 were expressed and increased significantly, but their inhibitors (TIMP-1 and TIMP-2) remained relatively unaltered in ischemic retina after RIRI in rats. These results suggest that MMP-2 and MMP-9 may play an important role in the pathomechanism of retinal ischemic injury.     

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.     

Protection of the retina from ischemia-reperfusion injury by L-carnitine in guinea pigs

PURPOSE: To investigate the efficacy of L-carnitine in preventing retinal injury followed by ischemia-reperfusion. METHODS: The eyes of 34 guinea pigs were used in this experiment. The guinea pigs were divided into two groups: the first group (n=17) was given L-carnitine intraperitoneally (500 mg/kg) and second group (n=17) received the same dose of saline solution. Under general anesthesia, peritomy was performed. Retro-orbital tissues were ligated for 90 minutes and ischemia was induced, followed by 4 hours of reperfusion. One of the enucleated eye was stained with hematoxylin and eosin (H&E) and retinal thicknesses were evaluated. Thiobarbituric acid reactive substances (TBARS) levels were determined in the retina of the other eye. RESULTS: Mean TBARS levels in retinal tissue were found lower in L-carnitine group (2.77 +/- 0.55 microM) than in the control group (6.57 +/- 1.19 microM), (p<0.01). On the other hand, mean retinal thickness was found to be increased in the control group (47.47 +/- 5.62 microm) when compared to the L-carnitine group (26.52 +/- 4.65 microm), (p<0.01). In correlation analysis, significantly positive relationships were found between retinal TBARS level and retinal thickness both in the control and L-carnitine groups (r=0.981, p<0.01 and r= 0.967, p<0.01 respectively). CONCLUSIONS: L-carnitine is effective in preventing retinal injury followed by ischemia-reperfusion.     

The purine nucleoside adenosine in retinal ischemia-reperfusion injury.

Adenosine, an intercellular messenger that is a product of the metabolism of ATP, plays a major role in neuronal and vascular responses of the retina to alterations in oxygen delivery. Significant changes in adenosine concentration have been measured in the retina during both ischemia and during the subsequent reperfusion period which result in important, but complex, functional effects. Adenosine A1 receptor stimulation produces a protective effect during ischemia, whereas overstimulation of the A2a receptor has deleterious effects. The mechanisms underlying these findings have not been completely determined, but most likely are the result of alterations in excitotoxicity, gene expression, and blood flow. Paradoxically, prolonged increases in adenosine concentration may be injurious to the retina, a consequence of superoxide radical formation secondary to adenosine catabolism. Adenosine is a critical mediator of blood flow changes in response to ischemia. It is a significant component of the retina's compensatory hyperemic response to ischemia, hypoxia, and hypoglycemia. Increasing endogenous adenosine concentrations may be useful in ameliorating post-ischemic hypoperfusion. Overall, current evidence suggests that adenosine is a vital component of the endogenous retinal response to substrate deprivation. Additionally, in vitro studies provide strong evidence that adenosine is a mediator of the formation and effects of vascular endothelial growth factor, which in turn promotes neovascularization. Finally, the ability of the retina to develop an ischemia-tolerant state by ischemic preconditioning is an intriguing phenomenon that reveals yet another essential role for adenosine in the retina's endogenous response to ischemia. The experimental results described in this review suggest that continued investigation into the role of adenosine in the retina may lead to important clinical applications for adenosine-based therapies that could decrease the incidence of retinal damage in ischemic vasculopathies such as diabetes, glaucoma, and retinal vascular occlusion.     

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。     

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...     

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。