The Mechanism Of Triamcinolone Acetonide In Inhibiting Retinal Neovascularizations In Oxygen-Induced Retinopathy Models

Part one:The mouse model of oxygen-induced retinopathy.Purpose To establish a mouse model of oxygen-induced retinopathy (OIR). Methods Six one week-old C57BL/6J mice were exposed to 75% oxygen for 5 days and then to room air for another 5 days as simple hyperoxia group. Six mice of the same age were kept in room air as simple control group. Fundus fluorescein angiography, adenosine dlphosphatase (ADPase) histochemical technique and counting the endotheliocyte nuclei of new vessels extending from retinal inner limiting membrane into the vitreous in ocular sagittal cross-sections were performed. Results In the simple hyperoxia group, the fundus fluorescein angiography discovered retinal neovascularization, the ADPase staining showed partial occlusion of retinal vascular and decreased vessel branches. However, Nomal retinal vessels were observed in the mice of simple control group. There was a mean amount of (24.8±7.1) endotheliocyte nucleis of vessels per cross-section in the simple hyperoxia group which was increased significantly compared with that of the simple control group (P<0.05). Conclusion The mouse model is reproducible and quantifiable.Part two:The mechanism research of triamcinolone acetonide in inhibiting neovascularization in OIR models.Purpose To investigate the possible mechanism of retinal neovascularization inhibitions of triamcinolone acetonide (TA) in OIR models. Methods 36 (72 eyes) 7 day-old C57BL/6 mice were used and divided into 4 groups.18 of them for the production of animal models of OIR, and one eye of each mouse received an intravitreal injection of 2μ1 of TA on postnatal day 12, as oxygen TA group; the same volume of BSS were injected into the other eye of the mice, as oxygen BSS group. The remaining two groups of mice raised under normal circumstances, the other steps were processed the same with the former two group, respectively, as normal BSS group and normal TA group. The fundus fluorescein angiography and ADPase histochemical technioue was used to assess the oxygen-induced changes of retinal vessels. The proliferative neovascularization was quantified by counting the endothellocyte nuclei of new vessels extending from retinal inner limiting membrane into the vitreous in ocular sagittal cross-sections. The protein contain of VEGF, SDF-1 and CD 14 was studied by immunohistochemistry. Realtime PCR analysis was performed to examine the expression of VEGF and SDF-1 mRNA. Results Compared with BSS hyperxia group, reduced density of retinal neovascularization was observed in the TA hyperxia group. The number of the endotheliocyte nuclei of new vessels extending from retina to vitreous was less in the oxygen TA group than in oxygen BSS group(P<0001). The protein contain of VEGF, SDF-1 and CD14 and the mRNA expression of SDF-1 and VEGF were significantly reduced in TA hyperxia group compared with BSS hyperxia group(P<0.05). The differences of protein and mRNA mentioned before in two normal groups were not significant(P>0.05). There was significant linear correlation between IOD/AOI values of VEGF and CD 14 (partial correlation analysis, P＜0.05), the correlation of IOD/AOI values of SDF-1 and CD 14 was significant too (partial correlation analysis, P<0.05). Conclusion The mechanism of neovessels inhibition of triamcinolone acetonide in OIR models was possible by reducing the accumulation of monocyte/macrophage and further decreasing the expression of VEGF and SDF-1.