Effects of melatonin,vitamin E and octreotide on lipid peroxidation 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 the 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 with a 6-h interval for a total daily dose of 10 mg/kg melatonin, 150 mg/kg vitamin E and 22 microg/kg octreotide. The first dose of each substance was administered 5 minutes before retinal ischemia, which was induced for 1.5 hours, followed by reperfusion for 24 hours. All three substances were repeated for 6, 12 and 18 hours during reperfusion. The animals were killed at 24 hours of reperfusion. Retinas were isolated and processed for the quantification of malondialdehyde (MDA). RESULTS: The compounds had the following relationships: melatonin more than vitamin E more than octreotide in preventing retinal damage by ischemia-reperfusion. All three gave significantprotection against the formation of MDA (10.4+/-2.3, 12.4+/-2.4, 13.9+/-1.5 nmol/100 mg tissue wet weight, respectively) compared to the control (3.7+/-1.3 nmol/100 mg tissue wet weight) and I/R groups (22.7+/-6.2 nmol/100 mg tissue wet weight). CONCLUSIONS: This study demonstrates the inhibitory effect of melatonin, vitamin E and octreotide on MDA levels during retinal ischemia-reperfusion injury.     

Effects of intraperitoneal vitamin E, melatonin and aprotinin on leptin expression in the guinea pig eye during experimental uveitis

PURPOSE: To observe ultrastructural changes and leptin expression in the guinea pig eye during experimental uveitis (EU) and the effects of vitamin E, melatonin and aprotinin on leptin expression. METHODS: Thirty male guinea pigs were randomly classified into five groups. Group 1 was the control group. Groups 2, 3, 4 and 5 received intravitreal injections of bovine serum albumin (BSA) to induce EU. At the same time on the third day, groups 3 (EU + vitamin E), 4 (EU + melatonin) and 5 (EU + aprotinin) received intraperitoneal vitamin E (150 mg/kg), melatonin (10 mg/kg) and aprotinin (20,000 IU/kg), respectively. On the sixth day, histopathological and clinical scoring of inflammation were performed, and leptin expression was investigated in the retina, choroid, sclera, episclera and cornea, and compared. RESULTS: There was a remarkable increase in leptin expression in the retina, choroid, sclera and episclera in the EU group. Leptin expression in the treatment groups was similar to that in the control group. At light and electron microscopic levels, ganglion cells were oedematous and inner plexiform layer thickness had increased in the EU group retinas. Oedema was decreased in the treatment groups. Comparison of the EU and treatment groups revealed significant differences histopathologically and clinically. CONCLUSION: Experimental uveitis causes an increase in leptin expression in the retina, choroid, sclera and episclera of guinea pigs. Vitamin E, melatonin and aprotinin inhibit this increase. Leptin seems to be closely related to ocular inflammation.     

Light and aging effects on vitamin E in the retina and retinal pigment epithelium

Experiments were performed to determine the effects of senescence and light adaptation on vitamin E levels in the neural retina and RPE-choroid-sclera of pigmented rats. Aging resulted in significant increases in alpha-tocopherol levels in both tissues, the effect being most pronounced in the RPE-choroid-sclera. The state of light adaptation had no influence on alpha-tocopherol levels in the neural retina at any of the ages examined, whereas in the RPE-choroid-sclera, alpha-tocopherol levels were substantially higher in light-adapted than in dark-adapted animals at all three ages (12, 22, and 32 months) at which they were measured. The effect of light adaptation on RPE-choroid-scleral alpha-tocopherol levels was most pronounced in the oldest age group.     

Response of guinea pigs to the synthetic peptide-M of the uveitogenic, retinal S-antigen: antisera immunofluorescent reactivity on normal guinea pig retina

S-antigen can elicit an experimental autoimmune uveitis (EAU) and pinealitis (EAP) in experimental animals. The sera of these animals have immunohistochemical reactivity with the photoreceptor cells of normal retina and pinealocytes. Lewis rats injected with the synthetic peptide-M corresponding to a specific sequence of S-antigen also develop an EAU and EAP. In this study we have investigated the immunohistochemical reactivity pattern of sera of guinea pigs injected with peptide-M. We found reactivity in the area of Muller's cells of normal guinea pig retina. Some of the sera showed weak reactivity with retina photoreceptors cells and pinealocytes. These patterns of reactivity are not seen in control sera of uninjected or saline in adjuvant injected guinea pigs. These results are consistent with observations of experimental and human uveitides.     

Protective effects of various antioxidants during ischemia-reperfusion in the rat retina

Background Oxidative stress during ischemia-reperfusion (I/R) is thought to be a major cause of retinal injury after I/R. The present study was aimed at investigating the protective role of antioxidant application.Methods Four commonly used antioxidants (vitamin E=alpha tocopherol, lutein, fenugreek=Trigonella foenum-graecum and germander=Teucrium multicaule) were applied in ischemia-reperfusion (I/R) injury of the right retinae of 51 adult pigmented rats. Each of the antioxidants was administered every 6 h, beginning 6 h before the ischemia. After 60 min ischemia and 24 h reperfusion, we assayed (1) oxidative damage by measuring malondialdehyde (MDA), (2) apoptosis by measuring activated caspase-3 (using immunoblots), and (3) intrinsic antioxidative capacity by measuring glutathione (GSH) levels in the retinae.Results In the order of lutein>Trigonella>vitamin E>Teucrium, all four compounds were effective in preventing retinal damage by I/R, as (1) they significantly decreased the formation of MDA (8.83, 16.48, 17.24, 18.5 nmol/100 mg tissue wet weight, respectively) compared with I/R without protection (23.29 nmol/100 mg tissue wet weight; controls: 8.0 nmol/100 mg tissue wet weight); (2) they significantly inhibited the activation of caspase-3 [0.01, 0.02, 0,02, and 0.04 arbitrary units (AU), respectively, versus control, 0.0, and I/R, 0.08 AU]; and (3) they significantly decelerated the loss of GSH (from control levels of 36.04 nmol/100 mg tissue wet weight) to 30.4, 15.98, 18.1, 15.02 nmol/100 mg tissue wet weight, respectively (lutein, Trigonella, vitamin E, Teucrium), compared with unprotected I/R (12.84 nmol/100 mg tissue wet weight).Conclusions Our study shows that lutein, Trigonella, Teucrium and vitamin E exert protection against in vivo retinal I/R injury in rats; this may recommend these compounds (in particular, lutein) for clinical use in patients with different types of ocular I/R injuries.     

Aprotinin reduces ischemia-reperfusion injury in the retina of guinea pigs

PURPOSE: The aim of this study was investigate the role of aprotinin on retinal lipid peroxidation and histopathological changes during ischemia/reperfusion (I/R) of guinea pigs. METHODS: Three groups of seven pigmented guinea pigs each were formed: a control (group 1), ischemia/saline (group 2) and ischemia/aprotinin (group 3). One eye of each animal was selected for histopathological evaluation and the other for biochemical assay. Bilateral pressure-induced retinal ischemia was instigated for 90 min and was followed by 24 hours of reperfusion. Animals in the ischemia/aprotinin and ischemia/saline groups received either 20,000 KIU/kg of aprotinin or saline, repeated four times at 6-hour intervals, with the first dose administered 5 min prior to the ischemic insult. The animals were killed at 24 hours of reperfusion. Retinal malondialdehyde (MDA) levels and the thickness of the inner plexiform layers were measured. RESULTS: The level of MDA in group 1 was significantly (p<0.001) lower than the other groups. The mean MDA level in group 2 was significantly (p<0.01) higher than in group 3. The inner plexiform layer in group 1 was significantly (p<0.001) thinner than in the other groups. The mean thickness of the inner plexiform layer in group 2 was significantly (p<0.01) higher than in group 3. CONCLUSIONS: These data indicate that intraperitoneally administrated aprotinin has a protective effect against I/R injury in the retina of guinea pig as evidenced by reduced retinal MDA level and retinal thickness.     

Dopaminergic and GABAergic amacrine cells are direct targets of melatonin: immunocytochemical study of mt1 melatonin receptor in guinea pig retina

Distribution of the mt1 melatonin receptor in the guinea pig retina was immunocytochemically investigated using peptide-specific anti-mt1 receptor antibody. Western blots of the guinea pig retina showed a single band at approximately 37 kilodalton (kD) immunoreactive to the anti-mt1 antibody. The most intense immunoreactivity for the mt1 receptor was detected in the cell bodies of ganglion cells. Their dendrites and axons were also immunolabeled. Subpopulations of amacrine cells, the inner plexiform layer, and the outer plexiform layer also exhibited moderate to weak immunolabeling. The mt1-positive amacrine cells were located either at the vitreal border of the inner nuclear layer or displaced in the ganglion cell layer. Double immunolabeling using antibodies to the mt1 receptor and tyrosine hydroxylase revealed that the majority of dopaminergic amacrine cells showed mt1 immunoreactivity. Almost all the ICA type dopaminergic cells were mt1 positive while the 2CA type cells less frequently exhibited mt1 immunoreaction. By double immunolabeling for the mt1 receptor and GABA, more than 50% of the mt1-immunoreactive amacrine cells were shown to be GABAergic neurons. Approximately one-third of the GABAergic amacrine cells were immunolabeled for the mt1 receptor. The present results demonstrate expression of the mt1 receptor in diverse neuronal cell types in the guinea pig retina and provide the first evidence for the direct effect of melatonin on dopaminergic and GABAergic amacrine cells via the mt1 receptor.     

褪黑素对早期糖尿病大鼠视网膜氧化应激反应的影响

背景氧化应激是糖尿病并发症的早期发生机制,而褪黑素是迄今已知最高效的抗氧化物质之一,目前国内就褪黑素对糖尿病并发症的防治机制研究尚不多见。目的研究褪黑素对早期糖尿病大鼠视网膜丙二醛（MDA）、还原型谷胱甘肽（GSH）含量及神经胶质纤维酸性蛋白（GFAP）表达的影响,探讨褪黑素对早期高血糖诱导的视网膜氧化损伤的作用。方法清洁级6周龄SD大鼠48只尾静脉注射质量分数2％链脲佐菌素（STZ）制作糖尿病模型,按随机数字表法分为模型对照组和褪黑素治疗组;尾静脉注射等量柠檬酸缓冲液的大鼠24只作为正常对照组。褪黑素治疗组每日腹腔注射褪黑素10mg／kg,正常对照组和模型对照组每日给予等量的生理盐水腹腔注射。于4、6、8周时采用MMT比色法检测视网膜组织匀浆中MDA、还原型GSH的含量,并应用Western blot和免疫组织化学法分析视网膜GFAP的表达量。结果造模后4、6、8周时褪黑素治疗组视网膜MDA含量均明显低于相应时间点模型对照组（P〈0．05）;4周、6周时与正常对照组比较差异无统计学意义（P〉0．05）,8周时高于正常对照组（P〈0．05）。模型对照组视网膜还原型GSH的质量分数均明显低于同时间点正常对照组（P〈0．05）;4、6、8周时褪黑素治疗组视网膜还原型GSH质量分数均明显高于同时间点模型对照组（P〈0．05）,4周、6周时与正常对照组比较差异无统计学意义（P〉0．05）,8周时低于正常对照组（P〈0．05）。4、6、8周时褪黑素治疗组视网膜GFAP的表达量均低于同时间点模型对照组（P〈0．01）;4周、6周时与正常对照组比较差异均无统计学意义（P〉0．05）,8周时高于同时间点正常对照组（P〈0．05）。结论褪黑素能降低糖尿病大鼠视网膜MDA的含量,增加GSH水平,抑制糖尿病大鼠视网膜GFAP的过度表达,进而减轻氧化应激引起的视网膜损伤。     

经瞳孔温热疗法对急性高眼压大鼠视网膜神经节细胞的保护作用

目的研究低阈值经瞳孔温热疗法（TTT）对急性高眼压大鼠视网膜神经节细胞（RGC）是否具有保护作用。设计实验研究。研究对象BN大鼠。方法采用810nm二极管激光机对10只大鼠视网膜进行热刺激，照射光斑1．2mm，能量50mW，照射时间20s，干预后3d光镜下观察视网膜形态结构的改变，免疫组化方法检测HSP70、HSP27在视网膜组织表达。采用上述激光参数，照射视网膜后3d，制作急性高眼压模型（TTT＋I/R组，n=10），采用TUNEL法检测RGC层细胞凋亡数量，及计数高倍镜下RGC层细胞数，与未干预的急性高眼压模型组（I/R组，n=10）、单纯TTT干预组（TTT组）及正常对照组（n=6）进行比较。主要指标免疫组化染色RGC细胞数及RGC层细胞凋亡数。结果采用低阈值TTT可诱导BN大鼠视网膜神经节细胞HSP70及HSP27表达，且光镜下未出现明显视网膜脉络膜形态的改变。TTT＋I／R组RGC层细胞凋亡数量明显少于I／R组（P=0．048），且前者RGC层细胞数量明显多于后者（辟0．016）；TTT组与正常对照组比较RGC层细胞凋亡数量无显著性差异（P=0．882），但RGC层细胞数明显少于正常对照组（P=0．001）。结论低阈值TTT可诱导BN大鼠视网膜HSP70、HSP27表达，并在急性高眼压损伤下对大鼠RGC凋亡具有抑制作用。（眼科，2007,16：48—51）     

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.     

黄芪对大鼠视网膜缺血再灌注损伤的影响

目的:观察黄芪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只大鼠随机分为3组:对照组、缺血组、保护组,采用前房灌注液体形成14.63kPa高眼压60min的方法建立模型,连续7d每天1次黄芪注射液6g/kg,ip,于手术前30min加注1次,对照组给予同等剂量的生理盐水。两组缺血60min后,分别再灌注0,2,6,12,24,48,72h,用比色法进行视网膜SOD、MDA、NO的测定,用光镜测量包埋切片的平均视网膜内层厚度。结果:黄芪能显著对抗大鼠视网膜缺血再灌注后MDA、NO水平的升高和SOD水平的降低,同时能改善平均视网膜内层厚度的变化。结论:黄芪可减轻大鼠视网膜缺血再灌注后的损伤,其机制可能与黄芪清除自由基,拮抗NO的毒性作用有关。     

Structural and elemental evidence for edema in the retina, retinal pigment epithelium, and choroid during recovery from experimentally induced myopia

PURPOSE: The purpose of this study was to monitor temporal changes in the retina, retinal pigment epithelium (RPE), and choroid of chick eyes using biometric, ultrastructural, and elemental microanalysis techniques as a means of visualizing more detailed signs of the physiological processes underlying choroidal expansion and refractive normalization during recovery from form deprivation. METHODS: Axial dimensions and refractions were measured on form-deprived and fellow eyes of 117 experimental chickens reared with monocular translucent occlusion from days 1 to 15 and given different lengths of visual experience (T = 0-144 hours) before death. Tissue was analyzed ultrastructurally by electron microscopy and relative sodium (Na) and chloride (Cl) ion abundances, by using x-ray microanalysis to determine changes in the presence of these indicators of tissue hydration. RESULTS: Refractive error decreased from more than 20 D of myopia almost linearly over the first 144 hours after occlusion. Concurrent changes in thickness in the retina, RPE, and choroid were seen as a series of thickness increases and edema, which returned to normal thickness, first in the retina, and did not reach maximum until 3 days after occluder removal in the choroid. In freeze-dried tissue, Na and Cl ion concentrations were greatest in the RPE photoreceptor outer segments and extravascular choroid at T = 0, decreasing toward fellow eye levels by T = 48 in the RPE and choroid. Na and Cl ion abundances in the frozen lymph of choroidal lymphatics were nearly at control levels (T = 0) and increased later as the vessels became more distended after the extravascular edema became significant. CONCLUSIONS: The results suggest that occluder removal induces edema across the retina and choroid and that this fluid may be the vector eliciting choroidal expansion during recovery from form deprivation possibly driven by the hyperosmolarity in the choroid, RPE, and photoreceptor outer segments that accompanies deprivation.     

豚鼠形觉剥夺性近视眼视网膜、脉络膜多巴胺代谢的变化

目的研究形觉剥夺对豚鼠神经视网膜、视网膜色素上皮（retinal pigment epithelium,RPE）／脉络膜复合体多巴胺（dopamine,DA）代谢的影响。方法28日龄豚鼠36只,分为3组：正常对照组、遮盖组、遮盖＋去遮盖组,每组12只。遮盖组用半透明眼罩遮盖豚鼠右眼14d,遮盖＋去遮盖纽在遮盖11d后去遮盖3d。14d后测定角膜曲率半径、眼球屈光度和眼轴长度。处死豚鼠,取眼后极部视网膜、脉络膜组织,用免疫组化染色和Western blotting法检测酪氨酸羟化酶（tyrosine hydroxylase,TH）蛋白在神经视网膜、RPE／脉络膜复合体的表达情况,用高效液相色谱检测神经视网膜、RPE／脉络膜复合体的DA、二羟基苯乙酸（3,4-dihydroxyphenylacetic acid,DOPAC）的含量。结果TH蛋白阳性表达于视网膜神经节细胞和内核层部分细胞,RPE／脉络膜复合体中表达阴性。遮盖14d后,豚鼠遮盖眼眼轴延长,近视形成,神经视网膜TH蛋白表达量和DA、DOPAC含量降低（P〈0．05）。遮盖＋去遮盖纽的遮盖眼近视程度低于遮盖组．其神经视网膜TH蛋白表达量和DA、DOPAC含量升高（P〈O．05）,但仍低于正常对照组（P〈O．05）。各纽豚鼠RPE／脉络膜复合体的DA、DOPAC含量比较,差异无统计学意义（P〉0．05）。结论形觉剥夺能调控豚鼠神经视网膜DA代谢,但不影响RPE／脉络膜复合体的DA代谢。     

促红细胞生成素对人视网膜色素上皮细胞氧化损伤保护作用及其机制

目的 观察促红细胞生成素（EPO）对人视网膜色素上皮（hRPE）细胞抗过氧化氢（H₂O₂）损伤的影响。方法以传代培养hRPE细胞为研究对象, 采用800μmol/L H₂O₂ 作用3 h 建立 hRPE 细胞损伤模型, 分为正常对照组、单纯损伤组、重组人EPO（rhEPO）治疗组。治疗组又根据加入rhEPO浓度不同分为10、20、40、60 IU/ml亚组。免疫组织化学方法检测细胞中核因子kappa B(NF-κB)的活化情况，比色法测定细胞脂质过氧化产物丙二醛（MDA）含量及乳酸脱氢酶（LDH）细胞释放率。结果 H₂O₂ 可使培养液中MDA及LDH释放率上升，单纯损伤组与正常对照组相比，差异有统计学意义（t_LDH＝29.746，t_MDA＝20.426，P＜0.05）；各治疗组与单纯损伤组比较，MDA及LDH释放率均有显著降低，差异有统计学意义（t_10IU＝5.770，t_20IU＝12.774，t_40IU＝19.818，t_60IU＝24.833，P＜0.05；MDA t_10IU＝5.345，t_20IU＝10.278，t_40IU＝18.571，t_60IU＝20.247，P＜0.05）；各治疗组相关分析显示，rhEPO浓度与LDH细胞释放率及MDA含量呈负相关（r=-0.976，P=0.024； r=-0.968，P=0.032）；rhEPO浓度与NF-κB核移位率呈正相关（r=0.998，P=0.002）；NF-κB核移位率与MDA含量呈负相关（r=-0.954，P=0.046）。结论 EPO能有效地拮抗 H₂O₂ 对hRPE细胞的脂质过氧化损害，其机制可能与活化NF-κB有关。     

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.     

形觉剥夺对豚鼠锥视蛋白表达的影响研究

目的探讨形觉剥夺对豚鼠锥细胞视蛋白表达的影响。方法出生1周的豚鼠28只,分为正常对照组和形觉剥夺组,各14只,按自然亮暗周期饲养。形觉剥夺组随机选取一只眼以半透明橡胶遮盖,正常对照组随机选择一眼作为对照。4周后取眼球行RT-PCR检测神经视网膜M-视蛋白和S-视蛋白的mRNA表达,并进行豚鼠视网膜铺片后免疫组织化学方法观察两种视蛋白的分布和表达密度,一抗为兔抗鼠红／绿锥视蛋白抗体或蓝锥视蛋白抗体,二抗为羊抗兔IgG带488荧光抗体。以Leica光学显微镜和Leica共聚焦显微镜观察豚鼠视网膜腹侧（下方）和背侧（上方）及中央区的锥细胞视蛋白的表达。结果实验前屈光状态为：对照眼（5．63±0．87）D,形觉剥夺处理眼（5．47±1．02）D,4周后屈光状态分别为：对照眼（4．38±1．02）D,形觉剥夺处理眼（-3．03±0．78）D;屈光度的改变分别为：（-1．25±0．53）和（-8．38±1．44）D。正常豚鼠的视网膜短波敏感锥细胞分布为腹侧（下方）多于背侧（上方）;中央密度最高,密度变化为突变。豚鼠的中波敏感锥细胞分布在背部（上方）多于腹侧（下方）,中央密度最高,密度变化为渐变;正常组短波敏感蛋白的表达密度：下方为（805．0±203．3）mm^-2,上方为（100．0±57．7）mm^-2;中央为（1637．2±314．1）mm^-2。形觉剥夺组：下方为（640．9±196．8）mm^-2;中央为：（1016．7±144．6）mm^-2,上方为（70．9±30．8）mm^-2;正常组M-视蛋白的表达密度：上方为（946．2±388．5）mm^-2,中心为（1666．7±137．8）mm^-2,下方为（175．0±100．9）mm^-2;形觉剥夺组：上方为（1436．7±366．0）mm^-2,中心为：（2780．0±180．5）mm^-2,下方为（318．2±172．7）mm^-2。RT-PCR检测示形觉剥夺眼和对照眼的M-视蛋白的相对吸光度值分别为1．06±0．07和0．51±0．10,S-视蛋白的吸光度值分别为0．70±0．07和1．25±0．06。形觉剥夺性近视眼视网膜3个观察区域M-视蛋白的表达均较正常对照增加,S-视蛋白的表达减少,两因素方差分析示差别均有统计学意义（P〈0．05）。结论形觉剥夺性近视眼M-视蛋白的表达增加,S-视蛋白的表达减少,提示感光细胞锥细胞的视蛋白表达有可能在近视的发生发展中起了作用。     

Effect of lipid-hydroperoxide-induced oxidative stress on vitamin E, ascorbate and glutathione in the rabbit retina

BACKGROUND: It is possible that oxidative stress causes several retinal diseases. However, the natural biogenic role of antioxidants in the retina is not clear. PURPOSE: This study investigates the change in concentration of vitamin E (VE), ascorbate and glutathione (GSH) in the retina following vitreous injection of 600 mug 18:2 linoleic acid hydroperoxide (LHP) in male New Zealand rabbits. METHOD: LHP was injected above the retinal surface. The animals were sacrificed and the eyes enucleated before LHP injection, 1, 3, 6, 12, 24 h and 4 and 7 days after LHP injection. Retinas were removed, VE and ascorbate measured by HPLC, and GSH determined by a fluorometric method. RESULTS: The concentration of VE in the retina decreased from pretreatment levels of 154.6 +/- 29.7 nmol/g wet weight (n = 7) and was lowest at 6 h (61.1 +/- 18.1 nmol/g wet weight, n = 4, p < 0.05), then increased gradually, returning slowly to pre-LHP levels by 7 days. The concentration of ascorbate in control retinas decreased at 6 h from pretreatment levels of 7.33 +/- 0.93 micromol/g wet weight (n = 7) to 2.74 +/- 0.16 micromol/g wet weight (n = 4, p < 0.05) and returned to pretreatment levels rapidly by 24 h after injection. The concentration of GSH in retinas decreased from baseline levels of 109.53 +/- 8.19 microg/g wet weight (n = 9), was lowest at 12 h (72.40 +/- 11.17 microg/g wet weight, n = 5, p < 0.05) and returned to pretreatment levels by 7 days. CONCLUSION: The results suggest that intravitreous LHP injection is a contributor to oxidative stress in the rabbit retina by causing a reduction in antioxidant capacity.     

视网膜Müller细胞调控豚鼠形觉剥夺性近视形成的研究

目的 研究视网膜Müller细胞在豚鼠形觉剥夺性近视形成中的作用.方法 眼罩遮盖建立豚鼠形觉剥夺性近视眼模型,分为正常对照组、DL-α-氨基己二酸(DL-α-AAA)组、生理盐水组、遮盖组、遮盖+DL-α-AAA组、遮盖+生理盐水组.DL-α-AAA组和遮盖+DL-α-AAA组右眼玻璃体内注射8 μg DL-α-AAA.14 d后检影验光测屈光度,A型超声测眼轴长度,免疫组织化学、Western blotting检测视网膜中Vimentin的表达,TUNEL染色检测凋亡细胞.结果 眼罩遮盖14 d后,豚鼠遮盖眼眼轴延长,近视形成.Vimentin蛋白阳性表达于视网膜Müller细胞.DL-α-AAA组右眼远视度数高于正常对照组,但视网膜Vimentin蛋白表达量下调(P＜0.05).DL-α-AAA引起遮盖眼近视度数减轻、视网膜Vimentin蛋白表达量下调(P＜0.05).各实验组的视网膜均未发现凋亡细胞.结论 玻璃体内注射DL-α-AAA能特异性作用于视网膜Müller细胞,有效抑制豚鼠眼球正视化和近视形成.     

急性视网膜缺血再灌注损伤后大鼠视网膜副凋亡和自噬的发生

目的　探讨大鼠急性视网膜缺血再灌注损伤（retinal ischemia-reperfusion injury,RIRI）后不同时间点视网膜中副凋亡及自噬的发生。方法　将30只健康成年SD雄性大鼠随机分为RIRI组及正常对照组。利用高眼压前房灌注法建立SD大鼠急性RIRI动物模型。正常对照组不做任何处理。急性RIRI后1 d、3 d、7 d、28 d各时间点取各组大鼠的视网膜组织,利用透射电子显微镜（transmission electron microscopy,TEM）检测视网膜神经节细胞（retinal ganglion cells,RGCs）副凋亡及自噬的发生;利用免疫荧光染色法检测视网膜微管相关蛋白1轻链3（microtubule associated protein 1 light chain 3,LC3）的表达。结果　急性RIRI后1 d持续至28 d,TEM可见RGCs细胞质空泡数量较正常对照组增高。急性RIRI后1 d持续至28 d,TEM可见RGCs细胞质中自噬体数量增加。正常对照组RGCs的细胞质中自噬体每50 μm²平均为0.79个,急性RIRI后7 d自噬体的平均数量达到高峰,每50 μm²平均为2.29个,与正常对照组相比差异具有统计学意义（P<0.05）。免疫荧光法检测发现,与正常对照组相比,急性RIRI后1 d开始,RGCs的细胞质中LC3表达增加,并在整个实验期间持续高表达,正常对照组RGCs层的LC3阳性细胞百分比为15.90%,急性RIRI后1 d、28 d时LC3阳性细胞百分比分别为46.95%和52.30%,与正常对照组相比差异均具有统计学意义（均为P<0.05）。结论　急性RIRI后RGCs涉及副凋亡和自噬的激活,各种类型的程序性细胞死亡可作为单一细胞死亡的形式或多种细胞死亡形式共存,参与急性RIRI视网膜损伤。     

Structural and functional maturation of the retina of the albino Hartley guinea pig

PURPOSE: Altricial animals, such as rats and mice, are born with their eyes closed, compared to precocial animals, such as guinea pigs and humans, which have their eyes opened at birth. The purpose of this study was to investigate if the retina of guinea pigs (precocial animal) is subjected to a postnatal maturation process similar to that previously reported for rodents. METHODS: Photopic and scotopic electroretinograms (ERG) and retinal histology were obtained from albino guinea pigs aged P1 to P75. RESULTS: Photopic ERG responses reached maximal amplitudes at P5 (a-and b-waves), that is 5 days (b-wave) to 10 days (a-wave) earlier than scotopic responses. However, the postnatal gain in b-wave amplitude was significantly (P < 0.05) more important for the cone (73.38 +/- 4.4%) signal than for the rod (15.23 +/- 3.96%), suggesting that the rod function is more mature at birth. Similarly, the short latency photopic oscillatory potential (ie: OP2) reached its maximal value 5 days (P10) earlier than its scotopic equivalent (P15), while the long latency OPs (ie: OP3, OP4), reached their maximal values nearly 20 days sooner in scotopic condition. Finally retinal histology revealed a thinning of the retina with age, the latter being most pronounced at the level of the ganglion cell layer (GCL). CONCLUSION: Our results thus confirm that despite its relative maturity at birth (compared to rodents), the retina of newborn albino guinea pigs undergoes significant postnatal maturation modifying its structure as well as its function, albeit not as extensive as that previously documented for altricial animals.