| Background and ObjectiveRetinal vascular occlusion is a common retinal vascular cause of visual loss.Treatment for the disease remains disappointing now. Schmidt and associates treated retinal vascular occlusion with selective ophthalmic artery fibrinolytic therapy in 1992.This treatment can increase drug concentration in diseased region.This technique is associated with low rate of systemic complications, but still not without complications, such as cerebral hemorrhage.Intravitreal injection with thrombolytic drug is a new technique to treat retinal vascular occlusion. It is a localised, targeted thrombolytic treatment as selective ophthalmic artery fibrinolysis, and avoid systemic complications. Lahey and associates have reported a pilot study of intravitreal tPA for retinal vascular occlusion in which 70% of patients had improved vision by 6 weeks. They hypothesised that intravitreal tPA diffuses across the retinal internal limiting membrane and into damaged retinal capillaries, but this has not been proved.Therefore,it is very important to study the change of retinal vessel after injected thrombolytic drug.Urokinase(UK) is one of the earlies thrombolytic drugs applied in clinic.It is nonantigenicity and nonpyrogenic.It can not cause hypersensitive response,so need no sensitivity test. It is low-toxin and low-side effect.It can be chronically administered for more than two weeks.Compare with tPA,UK is cheaper and more effective to lyze fibrin. Therefore,it is significant to study intravitreous injection with UK.In this experiment,we observed the expression of occludin in endothelial cells of retinal nerve fibre layer in different type of vasculars,and analyze the permeability of retinal vessel and the change of the blood-retinal barrier.To provide according to the process of thrombolysis and the treatment of retinal vascular occlusion.Materials and methodsTwenty SD rats were randomly divided into the experimental group and the control group,and 10 for each group. Right eye of each rat was invitreous injected as the experimental eye. Each rat in the experimental group was injected with 350U/4μl of urokinase,and each rat in the control group was injected with the same volume of 0.01M phosphate buffered solution (PBS).Eyes were enucleated after injected for 24 hours and devised a paraffin section technique. The sections were processed for pathological examination and observed the histomorphology of retina. The sections were processed for immunohistochemistry, and observed the expression of occludin in endothelial cells of retinal nerve fibre layer.Then apply the Leica DM1000 biological microscope, the Leica IM50 image acquisition system and the Image-Pro Plus 6.0 for images and datas.Statistical analysisThe datas apply SPSS 17.0 for statistical treatment. It apply Independent-Sample T Test to analyze the mean density values of occludin between the experimental group and the control group in different type of vasculars. A a-value of 0.05 was considered as the level of tests. A p-value less than 0.05 was considered to be statistically significant. Results1. The histomorphology of retina:the structure of retina is clear and complete in the control group. Smooth surface and clear boundaries between retinal layer is observed in the experimental group. And cells reducing in INL and wide cell gaps in INL and ONL are observed in the experimental group.2. The expression of occludin in the retinal vasculars endothelial cells:in the retinal nerve fibre layer of the control group,occludin is detected in all vasculars.In different type of vasculars, staining of occludin is intensely marked in the capillaries and the arteries. Comparing with the arteries, staining of occludin is less marked in the veins.In the retinal nerve fibre layer of the experimental group, occludin is also detected in all vasculars. In the capillaries of retinal nerve fibre layer, the expression of occludin in the experimental group is significantly lower than in the control group.But there is no change in the arteries or the veins.3. The quantitative analysis of occludin in the retinal vasculars endothelial cells: in the retinal nerve fibre layer, analyze the mean density values of occludin between the experimental group and the control group in different type of vasculars. The mean density values of occludin in the experimental group in the capillaries is 0.0743±0.0512, the mean density values of occludin in the control group in the capillaries is 0.0900±0.0584.The mean density values of occludin is statistically significant between the experimental group and the control group in the capillaries (t=2.021, P <0.05). The mean density values of occludin in the experimental group in the arteries is 0.1298±0.0591, the mean density values of occludin in the control group in the arteries is 0.1304±0.0604.The mean density values of occludin is not statistically significant between the experimental group and the control group in the arteries (t=0.067, P>0.05). The mean density values of occludin in the experimental group in the veins is 0.0483±.0309, the mean density values of occludin in the control group in the veins is 0.0492±0.0306.The mean density values of occludin is not statistically significant between the experimental group and the control group in the veins (t=0.205,P>0.05) Conclusion1. Intravitreal injection with urokinase can decrease the expression of occludin in the capillaries of retinal nerve fibre layer, and increased permeability of the retinal capillaries.2. The distribution of occludin was significantly different in different type of vasculars. |
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