Abstract
Purpose: :
Identification of genes which are differentially regulated in rat neuroretinas submitted to an experimental acute branch retinal vein occlusion (BRVO) in one eye, and to laser treatment in the contralateral eye, or to no treatment at all.
Methods: :
We have developed an in vivo experimental model of venous occlusion by photodynamic thrombosis in rat retinas. After anaesthesia, a sodium fluorescein solution was injected in the rat tail 15 minutes before the laser treatment. To induce ischemia in the tested retina, venous sites adjacent to the optic nerve head were photocoagulated with an argon laser. In one group of tested animals, the contralateral control retina was exposed to the laser treatment at sites located between major vessels. Because this treatment may still have an effect upon the choroidal blood flow, control rats were not subjected to the laser treatment. Retinal RNAs were isolated 30 minutes and 6 hours post occlusion and were processed for Affymetrix gene-chip analysis.
Results: :
This genome-wide screen enabled us to identify 22 and 128 genes which were consistently up- or down-regulated by venous occlusion, respectively, 30 minutes and 6 hours later. 595 genes were up- or down-regulated 6 hours later when we compared the transcriptomes of retinas in which vessels were occluded to that of controls not subjected to the laser treatment. Moreover, there were changes in expression of 216 genes in retinas which have been exposed vs. not exposed to the laser treatment. Up- and down-regulated genes encode transcription factors and co-factors, proteins involved in neuroprotection, in inflammation, in growth of blood cells and in pro- and anti-apoptosis.
Conclusions: :
Our microarray analysis revealed changes in gene expression bearing similarity to gene expression results from other ischemia models. Furthermore, it revealed that the laser treatment alone may have an unreported impact on retina’s metabolism.
Keywords: ischemia • gene microarray • laser