Abstract
Purpose: :
Branch retinal vein occlusion induces macular edema and impairment of visual acuity. In a rat model of branch retinal vein occlusion, we determined the changes in the gene expression of factors implicated in the development / resolution of retinal edema (VEGF-A, PEDF, Kir4.1, aquaporins 1 and 4) in the neural retina and pigment epithelium (RPE).
Methods: :
In one eye of adult Long-Evans rats, retinal veins near the optic nerve head were photocoagulated using a blue-green argon laser (parameters, 1.0 s, 50 microns, 50-100 mW). The untreated eyes served as controls. The eyes were enucleated one and three days after laser treatment, and the mRNA levels were determined with real-time PCR.
Results: :
In the neural retina, the expression of VEGF was significantly (P<0.05) upregulated one day after experimental vein occlusion, and returned to the control level after three days. In contrast, the expression of VEGF was not altered in the RPE. PEDF was significantly (P<0.001) upregulated in the neural retina and RPE three days after vein occlusion. Kir4.1 and aquaporins were downregulated in both tissues one and three days after vein occlusion.
Conclusions: :
During branch retinal vein occlusion, there is a time-dependent counter-regulation of VEGF and PEDF in the neural retina, with an early transient upregulation of VEGF, and a late upregulation of PEDF. The downregulation of Kir4.1 and aquaporins suggests an impairment in the retinal ion and water homeostasis that may contribute to the development of retinal edema and neuronal degeneration.
Keywords: vascular occlusion/vascular occlusive disease • vascular endothelial growth factor • gene/expression