Neuroprotective effect of sulfhydryl reduction in a rat optic nerve crush model

PURPOSE: The signaling of retinal ganglion cell (RGC) death after axotomy is partly dependent on the generation of reactive oxygen species. Shifting the RGC redox state toward reduction is protective in a dissociated mixed retinal culture model of axotomy. The hypothesis for the current study was that tris(2-carboxyethyl)phosphine (TCEP), a sulfhydryl reductant, would protect RGCs in a rat optic nerve crush model of axotomy. METHODS: RGCs of postnatal day 4 to 5 Long-Evans rats were retrogradely labeled with the fluorescent tracer DiI. At approximately 8 weeks of age, the left optic nerve of each rat was crushed with forceps and, immediately after, 4 muL of TCEP (or vehicle alone) was injected into the vitreous at the pars plana to a final concentration of 6 or 60 microM. The right eye served as the control. Eight or 14 days after the crush, the animals were killed, retinal wholemounts prepared, and DiI-labeled RGCs counted. Bandeiraea simplicifolia lectin (BSL-1) was used to identify microglia. RESULTS: The mean number of surviving RGCs at 8 days in eyes treated with 60 microM TCEP was significantly greater than in the vehicle group (1250 +/- 156 vs. 669 +/- 109 cells/mm(2); P = 0.0082). Similar results were recorded at 14 days. Labeling was not a result of microglia phagocytosing dying RGCs. No toxic effect on RGC survival was observed with TCEP injection alone. CONCLUSIONS: The sulfhydryl-reducing agent TCEP is neuroprotective of RGCs in an optic nerve crush model. Sulfhydryl oxidative modification may be a final common pathway for the signaling of RGC death by reactive oxygen species after axotomy.     

In vivo imaging and quantitative evaluation of the rat retinal nerve fiber layer using scanning laser ophthalmoscopy

PURPOSE: To determine whether scanning laser ophthalmoscopy (SLO) is useful for in vivo imaging and quantitative evaluation of rat retinal nerve fiber layer (RNFL) using an optic nerve crush model. METHODS: The optic nerve of the right eye was crushed intraorbitally with a clip. The left eye served as the untreated control. Fundus images of both eyes were recorded by SLO using an argon blue laser before and 1, 2, and 4 weeks after optic nerve crush. The focused plane was sequentially moved by changing the refractive values in the SLO setting. The range of refractive values (DeltaF) in which the RNFL reflex was clearly observed was determined. The RNFL thickness in retinal sections was measured and compared to the DeltaF value from SLO images taken before histologic preparation. RESULTS: Striations of RNFL radiating from the optic disc were clearly visible by SLO. No obvious changes in the RNFL reflex were observed 1 week after optic nerve crush. However, striations of RNFL became uniformly darker and thinner 2 weeks after the crush and were barely visible 4 weeks after the crush. The DeltaF value was unchanged 1 week after the crush, but then decreased significantly and progressively after the second week. DeltaF was unchanged in the control eyes during the experimental period. The DeltaF value correlated significantly with the histologically determined RNFL thickness. CONCLUSIONS: SLO is a useful and valuable tool for in vivo imaging and quantitative evaluation of rat RNFL.     

Detection of early neuron degeneration and accompanying microglial responses in the retina of a rat model of glaucoma

PURPOSE: To characterize the early reaction of retinal ganglion cells (RGCs) in a rat model of glaucoma using in vivo imaging and to examine the involvement of retinal microglia in glaucomatous neuropathy. METHODS: Glaucoma was induced in adult female Sprague-Dawley rats by cauterizing two episcleral veins, which resulted in a 1.6-fold increase in intraocular pressure (IOP). Retinal ganglion cells were retrogradely labeled with the fluorescent dye, 4-[didecylaminostyryl]-N-methyl-pyridinium-iodide (4-Di-10ASP) and monitored in vivo after elevation of IOP using fluorescence microscopy imaging. The number of RGCs was quantified on retinal flatmounts. Dying RGCs were surrounded by activated microglia that became visible after taking up the fluorescent debris. Immunocytochemistry was conducted to characterize further the ganglion cells and microglia. RESULTS: Cauterizing two of the four episcleral veins resulted in a consistent increase of IOP to 25.3 +/- 2.0 mm Hg, as measured with a handheld tonometer. IOP remained high for at least 3 months in glaucomatous eyes. The earliest sign of RGC death was detected in anesthetized animals 20 hours after induction of glaucoma. RGCs continued to decrease in number over time, with 40% of RGCs having degenerated after 2.5 months. Fundoscopic examination of the optic nerve head revealed cupping 2 months after induction of glaucoma. In addition, microglia were detected on retinal flatmounts as early as 72 hours after induction. Activated microglia and RGCs were also identified immunocytochemically, with an antibody against ionized calcium-binding adaptor molecule (Iba)-1 and an antibody specific to the 200-kDa subunit of the neurofilament protein, respectively. CONCLUSIONS: Occlusion of episcleral veins is a reproducible method that mimics human glaucoma, with chronically elevated IOP-induced RGC loss. This study shows that in vivo imaging permits the detection of ganglion cells in the living animal in the early stages of the disease and highlights the importance of in vivo imaging in understanding ophthalmic disorders such as glaucoma. Secondly, activation of intraretinal microglia coincides with degeneration of RGCs in glaucoma.     

A new calcium channel antagonist, lomerizine, alleviates secondary retinal ganglion cell death after optic nerve injury in the rat

PURPOSE: We investigated whether lomerizine, a new diphenylmethylpiperazine calcium channel blocker, exerted a neuroprotective effect on axonal or retinal damage induced by optic nerve injury in the rat. METHODS: A partial crush lesion was inflicted unilaterally on the optic nerve, 2 mm behind the globe, in adult Wistar albino rats. Animals were treated with the vehicle, 10 or 30 mg/kg lomerizine. Each solution was given orally twice daily for 4 weeks. One week before euthanization, Fluoro-Gold (FG) was injected into both superior colliculi to retrogradely label surviving retinal ganglion cells (RGCs). Approximately 1 month after the optic nerve injury, the retinal damage was assessed morphologically, and the optic nerve axons surrounding the initial lesion were examined histologically. RESULTS: The mean RGC density in the control group decreased to 65.9 +/- 1.32% of the contralateral eye, whereas the systemic application of 10 or 30 mg/kg of lomerizine significantly enhanced the RGC survival to 88.1 +/- 0.38% and 89.8 +/- 0.28%, respectively. Histological examination of damaged axons revealed no significant enhancement of the density or total number of axons of the retinal ganglion cells in the lomerizine-treated group. The crush force we employed caused no significant morphological differences in the retinal layers between the sham-operated animals and the animals from the experimental groups. CONCLUSIONS: Our findings suggest that lomerizine alleviates secondary degeneration of RGCs induced by an optic nerve crush injury in the rat, presumably by improving the impaired axoplasmic flow.     

RGC death in mice after optic nerve crush injury: oxidative stress and neuroprotection

PURPOSE: To establish a method for morphometric analysis of retrogradely labeled retinal ganglion cells (RGCs) of the mouse retina, to be used for the study of molecular aspects of RGC survival and neuroprotection in this model; to evaluate the effect of overexpression of Cu-Zn-superoxide dismutase (CuZnSOD) on RGC survival after severe crush injury to the optic nerve, and to assess the effect of the alpha2-adrenoreceptor agonist brimonidine, recently shown to be neuroprotective, on RGC survival. METHODS: A severe crush injury was inflicted unilaterally in the orbital portion of the optic nerves of wild-type and transgenic (Tg-SOD) mice expressing three to four times more human CuZnSOD than the wild type. In each mouse all RGCs were labeled 72 hours before crush injury by stereotactic injection of the neurotracer dye FluoroGold (Fluorochrome, Denver, CO) into the superior colliculus. Survival of RGCs was then assessed morphometrically, with and without systemic injection of brimonidine. RESULTS: Two weeks after crush injury, the number of surviving RGCs was significantly lower in the Tg-SOD mice (596.6 +/- 71.9 cells/mm(2)) than in the wild-type control mice (863. 5 +/- 68 cells/mm(2)). There was no difference between the numbers of surviving RGCs in the uninjured retinas of the two strains (3708 +/- 231.3 cells/mm(2) and 3904 +/- 120 cells/mm(2), respectively). Systemic injections of brimonidine significantly reduced cell death in the Tg-SOD mice, but not in the wild type. CONCLUSIONS: Overexpression of CuZnSOD accelerates RGC death after optic nerve injury in mice. Activation of the alpha2-adrenoreceptor pathway by brimonidine enhances survival of RGCs in an in vivo transgenic model of excessive oxidative stress.     

银杏叶提取物对视网膜神经节细胞保护作用的实验研究

目的探讨银杏叶提取物(EGb761)对大鼠视神经夹伤模型视网膜神经节细胞(RGC)的保护作用。设计实验研究。研究对象SPF级SD大鼠83只。方法右眼行视神经夹伤,于球后2mm处用40克压力微型视神经夹夹持视神经60秒,左眼作为正常对照。夹伤后2小时及此后每日一次灌胃给药,各组分别给予生理盐水5ml/kg(n=18)、1%灯盏细辛5ml/kg(n=16)、0.25% EGb761 5ml/kg(n=15)、1% EGb761 5ml/kg(n=18)和4% EGb761 5ml/kg(n=16)。视神经夹伤后第23天用荧光金作上丘逆行标记,第28天取眼球标本做视网膜铺片并拍摄照片,计数RGC并计算RGC的存活率。主要指标RGC存活率。结果生理盐水组、灯盏细辛组、0.25% EGb761组、1% EGb761组和4% EGb761组RGC存活率分别为60.59%、72.21%、69.10%、71.60%和74.20%。各剂量EGb761组与生理盐水组之间均有显著性差异(F=11.33,P<0.01),灯盏细辛组与生理盐水组之间也有显著性差异(P<0.01)。不同浓度EGb761各组之间无显著性差异(F=2.25,P>0.05),灯盏细辛组与不同浓度EGb761各组之间均无显著性差异(F=1.16.P>0.05)。结论EGb761能有效保护大鼠视神经夹伤模型的RGC。(眼科,2007,16:418-421)     

Tracking retinal microgliosis in models of retinal ganglion cell damage

Purpose. To investigate the longitudinal profiles of microgliosis after optic nerve injury induced by optic nerve crush and acute elevation of intraocular pressure (IOP). Methods. A confocal scanning laser ophthalmoscope was used to image the retinal microglia of the CX3CR1(GFP/+) transgenic mice in vivo at baseline, 3 days and then weekly for 4 weeks after optic nerve crush (n = 3), and after elevating the IOP to 110 mm Hg for 30 (n = 3) or 60 (n = 3) minutes. Results. After optic nerve crush, the density of microglia increased by 2.43 ± 0.19-fold at week 1 and then gradually declined with 2.04 ± 0.24-, 1.69 ± 0.25-, and 1.29 ± 0.11-fold increases at week 2, 3, and 4, respectively. Microgliosis followed a similar pattern after acute IOP elevation and the increase in microglia was associated with the duration of IOP elevation. There were 1.35 ± 0.17- and 2.03 ± 0.08-fold increases in microglia at week 1, and 1.15 ± 0.11- and 1.11 ± 0.10-fold increases at week 4, after 30 and 60 minutes of acute IOP elevation, respectively. The morphology of microglia changed from ramified to ameboid form in 1 week, and then returned to ramified form in the subsequent weeks. There was a significant negative association between the number of surviving retinal ganglion cells (RGCs) and the extent of microgliosis during the follow-up period (R(2) = 0.72, P = 0.004). Conclusions. Longitudinal in vivo imaging of the retinal microglia can provide an effective approach to study microgliosis and its association with RGC degeneration.     

大鼠视神经挫伤视网膜形态功能变化的动态研究

目的观察视神经夹挫伤后视网膜形态学和视功能动态变化,为视功能评价和视神经保护研究提供依据。方法大鼠视神经夹挫伤后1d、3d、5d7、d、9d、2周4、周8、周1、2周,光镜观察视网膜神经节细胞(RGC)改变,闪光视觉诱发电位(F-VEP)检测视功能状况。结果视神经部分损伤后3d到1周内视网膜神经节细胞快速减少,2周以后缓慢减少,4周几乎无明显变化;视神经损伤1d,F-VEP波形变得低而宽,前2周呈进行性下降期,4周后变化平稳,并显示恢复迹象。结论神经节细胞继发性损伤是视功能进行性下降的重要原因,一定数量存活的视网膜节细胞是视功能恢复的基础;神经损伤变化和视功能变化与时间具有一定的相关性,这些对于正确评价视功能状况和预后有极重要的意义。     

金丝桃素对视神经损伤大鼠视网膜节细胞的保护作用

目的观察金丝桃素对视神经损伤大鼠视网膜节细胞的保护作用。方法24只SD大鼠随机分为正常对照组、单纯夹伤组、生理盐水对照组、金丝桃素治疗组4组,每组6只（12眼）。对所有大鼠行双上丘注射2％荧光金逆行标记节细胞,7d后,对单纯夹伤组、生理盐水对照组、金丝桃素治疗组进行球后视神经钳夹．同时在生理盐水对照组、金丝桃素治疗组玻璃体内分别注入生理盐水和金丝桃素5ul,14d后进行视网膜节细胞的计数。采用SPSS13．0统计软件对所得数据进行t检验。结果视神经夹伤后14d,存活的视网膜节细胞显著减少。单纯夹伤组节细胞存活率为50％,生理盐水对照组节细胞存活率为52％,金丝桃素治疗组节细胞存活率为68％。金丝桃素治疗组相比单纯夹伤组和生理盐水对照组,存活的节细胞明显要多（P〈0．05）。结论玻璃体内注射金丝桃素能减少大鼠视神经损伤后视网膜神经节细胞的死亡率．对视网膜节细胞有保护作用。     

饱和氢气水对大鼠视神经夹伤模型视网膜神经节细胞保护作用的实验研究

 目的 探索饱和氢气水对大鼠视神经夹伤模型视网膜神经节细胞（RGC）的保护作用。设计 实验研究。研究对象 SPF级SD大鼠18只。方法 对18只大鼠采用随机数表法随机分为3组,每组6只。均选取右眼为实验眼,左眼为正常对照眼。使用40 g微型视神经夹在大鼠视神经球后2 mm处夹持60 s建立视神经夹伤模型。A组给予饱和氢气水腹腔注射,5 ml/kg,每日1次;B组和C组分别给予饱和氢气水和生理盐水滴眼,每次1滴,每日3次。用药第9天,麻醉下采用3%荧光金双上丘两点注射法逆行标记大鼠RGC,第14天深麻醉下取眼球并处死动物,行视网膜定向铺片,距离视乳头中心上下左右各2 mm 拍摄照片,盲法计数RGC。主要指标 RGC存活率。结果 A组、B组和C组RGC存活率分别为40.35%±13.04%、58.34%±14.00%和43.07%±7.80%（F=3.965, P=0.041）。其中B组与A组和C组之间均有显著性差异（P=0.020;P=0.042）;A组和C组之间无显著性差异（P=0.698）。结论 饱和氢气水滴眼2周对大鼠视神经夹伤模型视网膜神经节细胞可能具有一定的保护作用。（眼科,2014, 23： 107-110）     

灯盏细辛对大鼠视神经压榨伤后视网膜神经节细胞的保护作用

目的　探讨中草药灯盏细辛对大鼠标定性视神经压榨伤所致的视网膜神经节细胞(RGC)损伤的防护和修复作用。方法　 4 2只健康SD大鼠随机均分为A组和B组。两组均用特制微型视神经夹直接夹持视神经 ,制作成单眼视神经部分压榨伤模型后 ,A组不予任何治疗 ,B组予以灯盏细辛治疗 ,直至处死动物。以上两组按致伤日至处死日动物的存活时间又分为 :A1组和B1组 (损伤后 4d) ,A2 组和B2 组 (损伤后 14d) ,A3 组和B3 组 (损伤后 2 1d) ,每组各 7只大鼠。于处死前 3d双上丘直接注射 3%快蓝标记双眼RGC。处死日行眼球摘除术后 ,将双眼全视网膜组织铺片置于荧光显微镜下 ,在距视乳头 1mm处的颞上、颞下、鼻下及鼻上 4处作荧光摄影 ,并输入计算机经图像分析仪计数RGC。计算RGC标识率 ,即 (损伤眼RGC数 /未损伤眼RGC数 )× 10 0 % ,并进行统计学分析。结果　A组大鼠中 ,A1、A2 及A3 组的RGC标识率分别为 (77 79± 7 11) %、(6 3 76± 3 79) %、(5 4 6 6±4 75 ) % ;B组大鼠中 ,B1、B2 及B3 组的RGC标识率分别为 (80 13± 12 0 3) %、(78 17± 9 19) %及(83 5 9± 12 6 1) %。A2 和A3 组分别与B2 和B3 组比较 ,差异均有非常显著意义 (t=14 10 8,36 2 0 3;P<0 0 1)。结论　大鼠标定性视神经压榨伤后用灯盏细辛治疗 ,     

Latanoprost protects rat retinal ganglion cells from apoptosis in vitro and in vivo

We investigated whether latanoprost has a direct anti-apoptotic effect in retinal ganglion cell (RGC) line and RGCs in the rat. RGC-5 cells were induced to undergo apoptosis by serum deprivation and exogenous glutamate. The level of cell death with or without latanoprost acid was monitored by an XTT assay and by immunocytochemistry with activated caspase-3. Changes in the level of intracellular calcium ([Ca²⁺]i) were measured with fluo-4 fluorescence. The XTT assay revealed that latanoprost acid increased RGC-5 cell viability. Latanoprost acid significantly reduced caspase-3 positive cells and suppressed [Ca²⁺]i evoked by glutamate. U0126, a mitogen-activated protein/extracellular signal-regulated kinase 1 and 2 inhibitor, partially blocked the rescue effect of latnanoprost acid (p = 0.013). In vivo, rat RGCs were degenerated by optic nerve crush. After topical instillation of latanoprost for 7 days, RGCs labeled with fluorogold were significantly. Retinal flatmounts were subjected to terminal dUTP nick end labeling (TUNEL) staining to detect apoptotic cells. TUNEL-positive cells were significantly decreased in eyes with topically instilled latanoprost (p = 0.015). These data suggest that latanoprost has an neuroprotective ability in RGCs.     

A model to study differences between primary and secondary degeneration of retinal ganglion cells in rats by partial optic nerve transection

PURPOSE: To use a rat model of optic nerve injury to differentiate primary and secondary retinal ganglion cell (RGC) injury. METHODS: Under general anesthesia, a modified diamond knife was used to transect the superior one third of the orbital optic nerve in albino Wistar rats. The number of surviving RGC was quantified by counting both the number of cells retrogradely filled with fluorescent gold dye injected into the superior colliculus 1 week before nerve injury and the number of axons in optic nerve cross sections. RGCs were counted in 56 rats, with 24 regions examined in each retinal wholemount. Rats were studied at 4 days, 8 days, 4 weeks, and 9 weeks after transection. The interocular difference in RGCs was also compared in five control rats that underwent no surgery and in five rats who underwent a unilateral sham operation. It was confirmed histologically that only the upper optic nerve had been directly injured. RESULTS: At 4 and 8 days after injury, superior RGCs showed a mean difference from their fellow eyes of -30.3% and -62.8%, respectively (P = 0.02 and 0.001, t-test, n = 8 rats/group), whereas sham-operation eyes had no significant loss (mean difference between eyes = 1.7%, P = 0.74, t-test). At 8 days, inferior RGCs were unchanged from control, fellow eyes (mean interocular difference = -4.8%, P = 0.16, t-test). Nine weeks after transection, inferior RGC had 34.5% fewer RGCs than their fellow eyes, compared with 41.2% fewer RGCs in the superior zones of the injured eyes compared with fellow eyes. Detailed, serial section studies of the topography of RGC axons in the optic nerve showed an orderly arrangement of fibers that were segregated in relation to the position of their cell bodies in the retina. CONCLUSIONS: A model of partial optic nerve transection in rats showed rapid loss of directly injured RGCs in the superior retina and delayed, but significant secondary loss of RGCs in the inferior retina, whose axons were not severed. The findings confirm similar results in monkey eyes and provide a rodent model in which pharmacologic interventions against secondary degeneration can be tested.     

A novel neuroprotectant against retinal ganglion cell damage in a glaucoma model and an optic nerve crush model in the rat

PURPOSE: To investigate the effects of repeated treatments with a neuroprotective compound, R(-)-1-(benzo [b] thiophen-5-yl)-2-[2-(N, N-diethylamino) ethoxy] ethanol hydrochloride (T-588), on retinal ganglion cell (RGC) survival in rat eyes with elevated intraocular pressure (IOP) or after optic nerve crush. METHODS: An increase in IOP was induced by a single laser treatment to the trabecular meshwork in one eye of adult Wistar rats. Crush injury was unilaterally produced by clipping the optic nerve 2 mm behind the globe. RGC density was estimated by counting fluorescent dye-labeled cells in the flatmount of the retina. The optic nerve damage in the crush model was also evaluated histologically. RESULTS: In the elevated IOP model, RGC survival decreased to 72.9% +/- 3.8% (mean +/- SEM) of that of the contralateral control eye on the eighth day after laser irradiation. Repeated treatments with T-588 at 30 mg/kg twice daily significantly enhanced RGC survival (86.0% +/- 2.2%, P = 0.0242) without the reduction of IOP. In the optic nerve crush model, RGC survival diminished to 37.2% +/- 8.4% of that of the contralateral control eye after 4 weeks. Repeated applications with T-588 at 10 mg/kg twice daily significantly enhanced RGC survival (77.8% +/- 2.1%, P = 0.0038). Histologically, the rat optic nerve in the group treated with T-588 at 10 mg/kg retained a near-normal morphology. CONCLUSIONS: T-588 has a neuroprotective effect against RGC death caused by elevated IOP and optic nerve crush in the rat.     

Downregulation of Thy1 in retinal ganglion cells in experimental glaucoma

PURPOSE: Thy1 is a surface glycoprotein uniquely expressed in retinal ganglion cells (RGCs) in retina. The aim of this study was to investigate the expression change of Thy1 in a model of experimental glaucoma. METHODS: The change of protein and mRNA levels of Thy1 in the retina were studied using stereological counts of back-labeled RGCs, Western blot analysis, immunohistochemistry, and laser capture microdissection (LCM) of RGCs with quantitative PCR analysis of mRNA in a model of experimental glaucoma. LCM after optic nerve crush was also performed to evaluate Thy1 mRNA levels after a different injury. RESULTS: After 10 days of elevated IOP, there was a 34% loss of RGC number, Thy1 protein decreased 60% in eyes with elevated intraocular pressure (IOP), and Thy1 mRNA levels decreased 51% in RGCs. Both protein and mRNA level change of Thy1 is to a much greater extent than RGC number loss. CONCLUSIONS: The current results confirm that Thy 1 mRNA levels do not reflect the number of RGCs present and extend this to include a parallel decrease in Thy1 protein levels. These results suggest that Thy1 serves as an early marker of RGC stress, but not a marker of RGC loss, in models of retinal damage.     

Effect of glatiramer acetate on primary and secondary degeneration of retinal ganglion cells in the rat

PURPOSE: After crush injury to the optic nerve, elevated intraocular pressure, and glutamate toxicity, the immune modulator glatiramer acetate (GA, Cop-1; Copaxone; Teva Pharmaceutical Industries, Pitach Tikva, Israel) has been shown to reduce the delayed cell death of retinal ganglion cells (RGCs). This study was undertaken to confirm the protective effect of GA on secondary degeneration of RGCs in the rat, by using a spatial, rather than temporal, model. METHODS: A total of 131 Wistar rats divided into 10 groups underwent bilateral stereotactic injection of fluorescent tracer (Fluorogold; Fluorochrome, Denver, CO) into the superior colliculus to label RGCs. They received a concurrent subcutaneously injection of (1) GA mixed with complete Freund's adjuvant (CFA), (2) CFA alone, or (3) saline. One week later, the superior one third of the left optic nerve was transected in animals in the six partial transection groups. Optic nerves in four additional groups underwent full transection. Rats were killed and retinas harvested from both eyes 1 or 4 weeks after partial transection and 1 or 2 weeks after full transection. RGC densities were calculated from retinal wholemounts, and differences between right (control) and left (transected) eyes were compared across treatment groups. RESULTS: Among the partial transection groups, differences in the mean percentage of RGC loss in the inferior retinas were not significant at 1 or 4 weeks (ANOVA; P = 0.20, P = 0.12, respectively). After full transection, there was significantly more RGC loss in the GA group than in the CFA group when comparing whole retinas at 1 week, but not at 2 weeks (two-tailed t-test; P = 0.04, P = 0.36, respectively). CONCLUSIONS: There is no evidence that GA has a neuroprotective effect after optic nerve transection, either for primarily injured or secondarily involved RGC.     

大鼠视神经损伤视网膜病理改变的实验研究

目的研究现神经损伤早期视网膜的病理改变。方法采用大鼠球后视神经横断伤和钳夹伤模型,观察视网膜组织学及超微结构的改变。结果1）光镜：早期表现为神经纤维层血管扩张,损伤后7、14天可见散在的核染色质边聚。空化的节细胞。2）电镜：损伤后1天节细胞出现胞浆成分疏松,内质网扩张等变性样改变,横断伤3天及钳夹伤7天可见节细胞坏死,部分节细胞凋亡。结论视神经损伤导致节细胞出现迟发性死亡,提示早期治疗具有重要意义。     

视神经挫伤后视网膜形态学和Bcl-2/Bax表达

目的 研究大鼠视神经夹挫伤后视网膜神经节细胞（RGC）形态学改变及Bcl-2／Bax蛋白表达的变化，为了解视神经损伤的病理机制提供一定的依据。方法 建立大鼠视神经夹挫伤动物模型，伤后1d、3d、5d、7d、9d、2周、4周处死，HE染色观察RGC的动态变化，免疫组化方法检测RGC表达Bcl-2及Bax的水平。结果 视神经伤后RGC数目严重下降，2周内RGC快速减少，2周以后缓慢减少；伤后Bcl-2及Bax表达随时间而有不同程度的增加，Bax对损伤的反应较Bcl-2稍晚，两者表达均呈现先升后降的趋势，并维持一定的时间。Bcl-2和Bax蛋白表达比与RGC存活数目有一定的相关性。结论 视神经损伤后RGC数目减少是其视功能下降的病理基础之一，Bcl-2和Bax在RGC死亡机制中起重要作用，Bcl-2／Bax比率与RGC的减少呈一定的相关性。