[Expression of vascular endothelial growth factor and its receptor in experimental choroidal neovascularization in...

To study the expressions of vascular endothelial growth factor and its receptor FLK1 in krypton laser-induced choroidal neovascularization (CNV) in Brown Norway rat.

Thirty anesthetized male Brown Norway rats received krypton laser (647 nm, 360 mW, 50 micro m, 0.05 s) to induce CNV. Fundus fluorescein angiography examinations were performed just before euthanasia on days 3, 7, 14, 21, 28 and 56 after laser photocoagulation. The retina was processed for histopathology analysis. VEGF mRNA, VEGF and FLK1 expressions were demonstrated using in situ hybridization and immunohistochemistry staining respectively.

VEGF mRNA expression was mainly observed in the vascular endothelial cells, the ganglion cells, the inner nuclear layers, the retinal pigment epithelial cells in normal retina and the vascular endothelial cells of normal choroid of BN rat. VEGF mRNA expressed in the vascular endothelial cells, the ganglion cells, the inner nuclear layers, lesion of outer nuclear layers in retina on days 3 after photocoagulation, but CNV wasn't detected. The level of VEGF mRNA expression in retina was decreased after 3 days (P < 0.01). CNV was firstly observed on day 7 after photocoagulation by FFA and histopathology. The area and density of positively stained cells for VEGF mRNA in CNV were increased during the development of CNV (P < 0.01) and no significant change after days 21 (P > 0.05). FLK1 was detected in the vascular endothelial cells, the ganglion cells of normal retina and the vascular endothelial cells of choroid. The staining of FLK1 was positive in laser induced CNV after days 7, the level of the receptor expression was increased during the development of CNV (P < 0.01) and was not significantly changed after days 21 (P > 0.05).

VEGF and its receptor FLK1 accumulation and combination in the lesion of retina and choroid are related to choroidal neovascularization induced by laser.