| ObjectiveTo observe the changes of retina after repeated intravitreal injection of bevacizumab(trade name, avastin), discuss the possible side effect of bevacizumab treating for DR, and provide the basic rationale treatment for diseases about DR and other retinal neovascularization.Method1.40 male SD rats aged 12～14 weeks, weighed approximately 200g, were randomly devided into normal group(Group A) and diabetes mellitus groups,10 rats and 30 rats respectively. Diabetic rat models induced by streptozocin(STZ).After the model of DR was tested by ethidium bromide (EB) staining the retinal flat mounts,30 diabetes mellitus rats were randomly devided into DR group(Group B,10 rats), don't make any processing;The left eyes of the left 20 diabetic mellitus rats were as experimental group (Group C),3ul(25mg/ml) bevacizumab was injected into the vitreous in three times, interval time were 10 days;and the right eyes were given no treatment,as experimental control group(Group D).2. Retinal function tests were performed by Flicker Electroretinogram(F-ERG) after last intravitreal injection for Group C 20 days. EB staining and the retinal flat mounts, fluorescence microscopy were used to assess the retinal vascular pattern;Hematoxylin-eosin(HE) staining and light microscope were used to observed the morphological changes of the retina;immunohistochemistry staining was used to observe the masculine staining of the Thy-1 and VEGF in the retinas.3. Different treatment groups were analyzed by one-way ANOVA. Then SNK test to compare each group, P<0.05 as the standard of statistical significance.Result1. The results of F-ERG test showed that,in the implicit time of a and b-waves,the b-wave amplitude,the Ops-wave amplitude,the differences between group A,B,C and D were significant (F=33.165,36.162,19.955,23.243,p=0.000); in the a-wave amplitude,the differences between group A,B,C and D were no significant(F=0.097,P=0.961). 2. Vascular morphology and distribution were changed in the retina of DR rats and lose the normal distribution pattern.Retinal vascular was disorder.Fluorescein leakage and microaneurysms was showed in DR rats. Retinal vascular was thinner than normal after intravitreal injection of bevacizumab three times. The right eyes were better a litter than DR group.3. HE staining displayed that proliferative retinal vascular endothelial cell can be found from the HE staining in Group B. RGCs was less than normal after intravitreal injection of bevacizumab in the left eyes of DR rats three times,the right eyes were better a litter than DR group.4. Thy-1 mainly located in the ganglion cell layer (GCL) and a weak postivity in the inner plexiform layer (IPL) and inner nuclear layer (INL). The difference of mean IOD of Thy-1 among every group had statistical significance(F=25.819,P=0.000). Futher more, we compared each group with SNK test, the difference between Group C and A, B, D were significant(P<0.05),the difference between Group B and A were significant (P<0.05), the difference between Group B and D were significant (P< 0.05).VEGF mainly located in the GCL and a weak postivity in the nerval fiber layer (NFL), INL and retinal pigment epithelial (RPE) layer. The difference of mean IOD of VEGF among every group had statistical significance(F=45.243,P=0.000). Futher more, we compared each group with SNK test, the difference between Group B and A,C, D were significant (P<0.05).Conclusion1.Repeated intravitreal injection of bevacizumab for DR, RGCs was less than normal.2. Repeated intravitreal injection of bevacizumab for DR, retinal vascular was thinner than normal.3. Repeated intravitreal injection of bevacizumab for DR,the ather eye was affected. |
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