Effects of arteriolar constriction on retinal gene expression and müller cells in an experimental retinal vein occlusion

Abstract

AbstractPurpose To investigate the effect of the laser‐induced arteriolar constriction (AC) on branch retinal vein occlusion (BRVO) induced Müller cell responses and alterations in gene expression of factors implicated in the development of edema.Methods In Brown‐Norway rats the BRVO was induced by laser photocoagulation of the veins in one half of the retina. AC of the afferent arterioles was performed 30 minutes later. The expression of Vegfa, Vegfb, Pedf, Kir4.1, Aqp4, Aqp1, Il1ß, and Il6 was determined with RT‐PCR in the retina and retinal pigment epithelium (RPE) after 1, 3 and 7 days. Potassium currents were recorded in Müller cells 3 days after BRVO. Immunostaining against GFAP, Aqp4 and Kir4.1 was performed on day 1 and 3.Results BRVO resulted in the neuroretinal transient upregulation of Vegfa on day 1. The expression of the Kir4.1, Aqp4, and Aqp1 channels were downregulated, and Il1ß and Il6 strongly upregulated, on day 1 and 3. The retinal distribution of GFAP and Aqp4 proteins remained unaltered, while the Kir4.1 protein displayed redistribution from a polarized to a uniform retinal distribution. Müller cells showed cellular hypertrophy and a decrease in potassium currents. AC accelerated the restoration of downregulated Kir4.1, Aqp4, and Aqp1 in the RPE, of Kir4.1 in the neuroretina and of upregulated Il6 in the neuroretina. AC did not influence the gliotic alterations of Müller cells and the redistribution of Kir4.1 protein.Conclusion The constriction of the afferent artery in the BRVO region had only marginal effect on the BRVO‐evoked alterations in retinal gene expression.