| Objective: Neovascular glaucoma (neovascular glaucoma,NVG)isneovascularization of the iris and angle glaucoma is characterized by the performance ofmajor vascular diseases related to hypoxia and cause eye, an eye variety of structuraldamage, blindness rate high eye. The fibrovascular membrane by histopathologicaltouched upon muscle proliferation of fibroblasts and neovascularization[1].Theneovascularization of iris,(Neovascularization of iris, NVI) is secondary to manycommon pathology of the eye and systemic disease, ischemia and hypoxia insided eye,and a lot of other factors are responsible for a large number of angiogenic growth factorupregulation of expression, resulting in increased vascular permeability and endothelialcell proliferation, neovascularization and the formation of the critical steps. The surfaceof the iris and angle neovascularization further development of combined fibrovascularmembrane formed, blocking the cornerstone structure, leading to the closure of theangle and serious secondary neovascular glaucoma. The growth and development of irisneovascularization process of vascular endothelial growth factor (Vascular EndothelialGrowth Factor, VEGF) and insulin-like growth factor-I (Insulin-like Growth Factor-I,IGF-I) and its receptor play an important promoting and leading role.NVI in this studywas established by inducing the anterior segment ischemia of rabbit and to provide astable animal model for studying on treatment and understanding the mechanism ofneovascularization related diseases. The number of new blood vessels were counted byH&E staining under light microscope, and immune-histochemical staining method todetect expression VEGF and IGF-I protein level, ELISA to determinate the expressionof VEGF and IGF-1changed in the organization of aqueous humor and serum tissue atdifferent time points. A lot of experimental studies reported about that there is a relation between retinal and choroidal neovascularization and IGF-I, but NVI secondary to NVGwas rarely reported in the scholarly articles. So this study was to identify thepathological mechanisms, growth promoting effects of vascular factors, involved inNVG for providing the new issues and methods for clinical applications of NVG.Methods: The14male New Zealand white rabbit’s models, weighing1.5-2kg,drinking water and giving a normal diet, and then randomly divided into normal groupand model group. Normal group eyes only simply open the conjunctival sac withoutapplying any suture after surgery. The model group eyes’ were performed the inferiorrectus transection with merge four vortex vein occlusion surgery. Slit lamp observationwas performed on each rabbit from1day before and1day after, day3, day5, day7,day9, day11and all of the rabbits were hanged in day11. Normal group only do slitlamp observation. Two sets of anterior segment of killed rabbit’s eyes were taken andthen fixed, embedded, sliced, and iris tissue morphology, quantity of neovascularizationand its pattern were observed under light microscope. The number of neovascularizationwas counted under H&E staining, immunohistochemical staining was used to measurethe protein level of vascular endothelial growth factor (VEGF) and insulin-like growthfactor-I (IGF-I), then compared the differences in VEGF and IGF-1expression.ELISA method was used to measure the VGEF and IGF-1protein level changes inaqueous humor tissue at different time points (day1, day3, day5, day7, day9and day11).Results:1. Compared with the same period in the normal group, model group (day11) irisneovascularization quantity increased significantly, has statistically significant (P<0.05).2. The iris tissue sections of model group at day11showed more VEGF and IGF-1protein level expression than normal group and is significantly higher than normalrabbits’ eyes.(P <0.05).3. Neovascularization in model group is significantly higher than normal group,level of both VEGF and IGF-1in aqueous humor at different time points and also thelevel of protein expression are significantly increase in model group (P <0.05).4. The level of VEGF and IGF-1are gradually increased in the serum and modelgroup is significantly higher than normal group (P<0.05).Conclusion:1.The anterior segment ischemia and hypoxia is related to neovascularization ofiris in rabbits’ eyes model. The rabbit model has accurate position of anterior segment position and iris neovascularization is easily detectable, so it is a suitable model of irisfor studying pathogenesis and pharmacological intervention for neovascularization.2. VEGF and IGF-1expression was increased in the ischemia induced irisneovascularization of anterior segment significantly, is closely related to the incidenceof iris neovascularization and neovascular glaucoma, promote the regulation ofangiogenesis.3. VEGF and IGF-1expression was increased gradually in the ischemia inducedanterior segment iris neovascularization model. Therefore, VEGF and IGF-1involvedin the regulation of angiogenesis and closely related to neovascularization. Hence, thiswill provide a new idea about the future research and finally in clinical application ofmicro-vascular ocular diseases. |
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