Objective To observe the effect of persistent flickering stimulus on the structure and function of retina in guinea pigs during a developmentally sensitive period.Methods Twenty-four two- week-old guinea pigs were randomly divided into flicker light (FL) group and control group, with 12 guinea pigs in each group. Animals in FL group were raised under 500 Lux illumination with a duty diurnal cycle of 50% at a flash rate of 0.5 Hz. Animals in control group were reared under steady 500 Lux illumination. Light emitting diode (LED) lamps were used for lighting under a 12-hour light/12-hour dark cycle. After the collection of fundus photographs and electroretinograms recorded at week 12, eyeballs were taken out, three dimensions were measured, and histopathological changes were examined.Results Compared to control group, tessellated fundus in FL group appeared more prevalent; implicit time of ldquo;ardquo; waves were prolonged in electroretinogram; the eyeballs were increased in horizontal, vertical, axial dimensions by (0.89plusmn;0.30), (0.69plusmn;0.20) and (0.96plusmn;0.30) mm respectively, the differences between two groups were statistically significant (t=12.7,11.9,15.8;P＜0.05). The gap of sclera collagen fiber was slightly widened.The photoreceptor layer was more likely to develop a disordered outer segment, which contained deciduous disc membranes.Conclusion Persistent flickering stimulus is attended by development of excessive ocular enlargement,which could affect the retinal structure and function of photoreceptors.
Objective To observe the inhibitory effects of construction of complement factor (CFB)small interference RNA (siRNA) on choroidal neovascularization（CNV）induced by photocoagulation in rats.Methods We constructed an expression vector of CFBsiRNA by cutting CFBsiRNA and plasmid pRNATU61/Neo. Experimental CNV was induced by photocoagulation in 42 Brown Norway rats. After the model was set up, the rats were randomly divided into tail intravenous injection, vitreous injection, subretinal injection, and control group; each group except the control one had a corresponding blank plasmid control group. CFBsiRNA was injected 1, 3, and 5 days respectively after photocoagulation in the injection groups; the dosage was 50, 20, and 10 mu;g in tail intravenous injection, vitreous injection, and subretinal injection group respectively, while no injection was give to the control group after photocoagulation. Before and 14 days after photocoagulation, fundus fluorescein angiograoph (FFA) was performed and CNV development was judged by the leakage; the expression of vascular endothelial growth factor (VEGF) and factor Ⅷ were detected by immunohistochemistry. Results The leakage of fluorescein was obvious lower in tail intravenous injection group than that in the control group (chi;2=15.1620,Plt;0.05). The expression of VEGF and factor VIII in tail intravenous injection group at different time points after photocoagulation didnprime;tdiffer much (F=20.35,18.33; Pgt;0.05); while was apparently lower than that in the other groups at different time points (F=77.96,55.68; Plt;0.05).All of the groups, except tail intravenous injection group, had higher expression of VEGF and factor VIII 14 days after photocoagulation compared with that 7 days after photocoagulation (F=60.89, 61.12; Plt;0.05).Conclusions Constructed CFBsiRNA can inhibite CNV by downregulating the expression of VEGF and factor Ⅷ.
Objective To determine the effect of thiazolidinediones (TZDs) on early retinopathy in rats with experimental diabetes. Methods In 40 rats, diabetic models were set up in 36 by one-off intraperitoneal injection with streptozotocin (STZ), and other 4 were in the normal control group. Twenty-four diabetic rats with the disease-duration of more than 6 months underwent intravitreous injection (with rosiglitazone or pioglitazone in 10 rats, respectively), and the rest 4 rats werenprime;t injected with drugs as the diabetic positive control group. Immunohistochemical treptomycin-avidin-biotin-complex (SABC) method, in situ hybridization of retinal vascular endothelial growth factor (VEGF) mRNA, and TdT-dUTP terminal nick-end labelling (TUNEL) were performed on the ocular paraffin section to detect the cellular apoptosis. The difference of VEGF expression and cellular apoptosis between TZDs and control group was observed and analyzed. Results The results of immunohistochemical staining and hybridization in situ were negative in the normal control group. The positive expression rate of VEGF was lower in rosiglitazone and pioglitazone group than which in the diabetic positive control group, and there was no obvious differences of positive expression of VEGF mRNA and cellular apoptosis between the 2 groups. Conclusion TZDs (rosiglitazone and pioglitazone) may inhibit the positive expression of VEGF protein in retina of STZ-induced diabetic rats to some extent, but not affect the growth of VEGF in retina. (Chin J Ocul Fundus Dis, 2006, 22: 7-10)
Objective To observe the histological changes and apoptosis of retinal cells in pigmented rabbits treated by transpupillary thermotherapy (TTT) with different laser power. Methods Fourteen pigmented rabbits (28 eyes) were divided averagely into seven groups（control group, 50, 70, 90, 110, 130, and 150 mW group）according to different laser power of TTT. Light microscopy was performed to observe the histological changes, and TDT-mediated biotin-dUTP nick-end labeling (TUNEL) technique and flow cytometry (FCM) examination were used to detect the apoptotic cells 24 and 48 hours after photocoagulation, respectively. Results The color of retinal burn speckles changed from offwhite to white and super white with the diameter enlarged gradually as the laser power of TTT increased. The results of light microscopy revealed that compared with the control group, the retinal tissue did not change much in 50-70 mW group; in 90-130 mW group, the retinal structure was integrated, but the cone and rod cells became swollen and condensed nuclei and cytoplasmic vacuolization were seen in the inner nuclear layer. The difference of retinal structure in 50-130 mW group 24 and 48 hours after photocoagulation and control group was not significant. In 150 mW group, tumefaction and degeneration were observed in each layer of retina and the inner and outer segments of photoreceptor cells lost 24 hours after photocoagulation, and obvious necrosis and cell loss of retinal tissues were detected hours after photocoagulation. The results of TUNEL examination indicated that positive cells were found in outer nuclear layer in each photocoagulation group which increased as the laser power of TTT was enhanced; the apoptosis gradually involved the inner nuclear layer and ganglion cell layer. The results of flow cytometry (FCM) examination showed the peak of apoptotic cells in each photocoagulation group 24 hours after photocoagulation. Conclusion Under certain subthreshold photocoagulation (50-70 mW), retinal tissue of rabbits does not change much but apoptosis of photoreceptor cells increase significantly. As the laser power of TTT increases, the retinal tissues become swollen, degenerated and even necrotic; cellular apoptosis gradually involves the inner nuclear layer and ganglion cell layer. (Chin J Ocul Fundus Dis, 2006, 22:249-252)
Objective To detect expression of NF-κB in the inner retina and in vestigate the inhibitoryeffect of pyrrolidine dithiocarbamate on retinal neovascularization in rats. Methods The rat models with retinopathy were set up un der the hypoxia condition, and fluorescein fundus angiography (FFA) was used to observe the retinal neovascularization. The expressions of NF-κB in the inner retina in rats with and without neovascularization were detected by immunohisto chemical method. PDTC was intraperitoneally injected in rats with neovascularization to observe the expression of NF-κB in the inner retina and the effect on retinal neovascularization. Results Hypoxia induced NF-κB activation in the retinal glial cells and endothelial cells. But immuno-staining intensity for NF-κB and adhesion molecules were reduced by PDTC intraperitoneal injection. Retin al angiogenesis in rats were suppressed effectively (P＜0.05). Conclusions NF-κB activation correlates with retinal neovascularization closely. PDTC may inhibit the NF-κB activation and prove beneficial in the treatment of ischemic neovascularization. (Chin J Ocul Fundus Dis，2003，19：201-268)
Objective To monitor the release of amino acids of the whole retina during and after experimental glaucoma by increasing the intraocular pressure （IOP）． Methods Experimental glaucoma was induced in one of the two eyes of rabbits by increasing IOP at 120 mm Hg for 45 min under infusion of saline in anterior chamber；then the pressure was released and the needle inserted into the anterior chamber was removed，this state was maintained for another 45 min．Every 15 min during the experiment 5 rabbits were killed and experimental eyes were enucleated．Aliquots（20 μl）of the retinal extracts（see below）were mixed with ophthaldialdehyde reagent and analysed for amino acid content by the HPLC method of Wangwei，using a 150 mm×4.6 mm,5 μm C18 column． Results A large increase in the release of glutamate，but not of the other three amino acids monitored，occurred during initial experimental ocular hypertension．It reached peak value of（111.73±17.46）10-5 mmol/g at 15 min of hypertension．15 min after release of intraocular pressure，again，immediately large and specific increase in the concentration of glutamate was reached to（102.96±51.91）10-5 mmol/g．In eyes subjected to paracentesis of anterior chamber，no difference was found between experimental eyes and controls. Conclusion These results suggest that glutamate is triggered by increasing the IOP，and it releases not only during the period of experimental ocular hypertension，but also afterwards. (Chin J Ocul Fundus Dis, 2002, 18: 146-148)
Objective To investigate the damage to the retinal cells and apoptosis of retinal cells of rats after ischemia-reperfusion insult. Methods The retinal ischemia-reperfusion model was developed by increasing intraocular pressure to 109725 mm Hg in rat eyes. Morphological changes of the rat eyes were observed by means of routine histopathology with HE staining. Apoptosis of the retina was assayed by both DNA fragmentation gel-electrophoresis and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labelling (TUNEL). Results Compared with the normal control, no histopathological changes were revealed in the rat retinas 30 min after the ischemia and then reperfued for 24 h or 48 h. Retinal ganglion cell layer (RGL) and inner plaxiform layer (IPL) of the retina were observed, however, to become significantly thinner 60 min after the ischemia and then reperfued for 24 h or 48 h. Together with the pathological changes DNA ladder pattern was detected in the same group of the rats. Further, immunochemical stain of the eye demonstrated that TUNEL positive cells were localized in RGL and IPL of the retina. Conclusion Ischemia-reperfusion insult of the eye may remarkably damage the retina of the rat eye. The damage to the retinal cells is mainly localized within RGL and IPL and apoptosis is the important mechanism of the retinal disorder. (Chin J Ocul Fundus Dis, 2002, 18: 296-298)
Objective To investigate the effect of suppression of ischemia-induced retinal neovascularization by VEGF antisense oligodeoxyribonucleotides. Methods Mouse models of hyperoxia-induced ischemic retinopathy were established. Retrobulbar injections were performed with VEGF antisense oligodeoxyribonucleotides or NS in 4 groups:normal control and various doses respectively. The nuclei of new vessel buds extending from the retina into the vitreous in differ ent groups were counted and compared under the light microscope. Results There were plenty of new vessel buds in the eyes of mice in hyperoxic condition., while the number of the nuclei of new vessel buds is less in the murine eyes with retrobulbar injection of VEGF antisense oligodeoxyribonucleotides,especially the nuclei were redused with 59.3% in eyes with large dose. Conclusion The proliferation of retinal new vessel may be suppressed by using the retrobulbar injection of VEGF antisense oligodeoxyribonucleotides. (Chin J Ocul Fundus Dis, 2001,17:141-143)
Objective It has been shown that pigment epitheliumderived factor (PEDF) is an effective anti-apoptosis agent on several kinds of cells of the central nervous system.This study aimed to evaluate the effect of PEDF on pressure induced retinal ischemia in a rat model. Methods Retinal ischemia was induced by increasing the intraocular pressure to 110 mm Hg for 45 minutes via an intracameral catheter.Ten microlit ers (0.1 mu;g/mu;l) PEDF was injected into the vitreous of 4 eyes of each group im mediately after reperfusion and 4 additional eyes received only normal saline as vehicle controls.The animals were euthanized at 2 or 7 days after reperfusion.T he effect of PEDF on retinal degeneration was assessed by measuring the thicknes s of the inner retinal layers (MTIRL) and counting the retinal ganglion cells (R GC) on plastic embedded retinal sections. Results The MTIRL and the RGC counting in eyes treated with intravitreal PEDF were significantly higher than those in vehicle controls (118.1plusmn;5.0) mu;m vs(94.9plusmn;3.0) mu;m (Plt;0.05);(6.0plusmn;1.0) cells/100 mu;m vs (4.5 plusmn;0.5) cells/100 mu;m (Plt;0.05) 7 days after reperfusion,respectively． Conclusion Intravitreal administration of PEDF can ameliorate an ischemiareperfusion retinal injury and may be useful to prevent neuronal degeneration in the inner retina. (Chin J Ocul Fundus Dis, 2001,17:138-140)
Purpose To investigate nucleoside diphosphate kinase (NDPK ) expression of tumor metastasis suppressor gene nm23 in heterotransplanted model of retinoblastoma(RB) in nude mice，and analyse the correlation between the expression of nm23 gene and the formation and progression of heterotran splanted RB． Methods SP immunohistochemical method was used to detect the expression of nm23 gene product NDPK in 20 tumors of heter otransplanted RB model and normal retinal tissue． Results The negative staining of nm23/ NDPK was found in normal retinal tissue , whereas 100% expression rate in RB tumors with positive number of 48.73plusmn;2.37． No statistical significance of the expression of nm23/ NDPK was observed between the intraocular growth phase （I～Ⅲ grade） and invasive phase （ Ⅳ～Ⅴ grade）in heterotransplantedRB tumors． Conclusion The function of nm23 gene as a tumor metastasis suppressor in heterotra nsplanted RB tumors was less prominent ,but it may play a role in carcinogen esis and progrssion of RB and may predict poor prognosis． (Chin J Ocul Fundus Dis, 2001.17:47-49)