Abstract
Purpose: :
Retinal degeneration is a disease characterized by the loss of photoreceptors. Murine models have been established for such degenerations, and a variety of methods have been used to follow the progression of the disease. Although pathologies are well established for most retinal degeneration diseases the cellular responses remain often elusive. The current study defines the gene expression responses in the various retinal cell types during the period of rod and cone death in the rd1 mouse model.
Methods: :
A preliminary microarray analysis led to the selection of 183 genes whose levels changed during degeneration. Probes corresponding to these genes were used for in situ hybridization on tissue prior to the onset of degeneration, as well as during the periods of major rod and cone death. Expression values were assigned for the intensities of in situ hybridization signals and were compared between mutant and wild–type tissue.
Results: :
During the peak of rod death, genes with a change in expression intensity were typically lower in the mutant, and were usually expressed in ganglion, amacrine and horizontal cells. In contrast, during the peak of cone death, genes that changed in expression intensity were more likely to be elevated in the mutant, with expression throughout the inner nuclear layer and ganglion cell layer. In many cases, ectopic expression was observed in bipolar cells and Muller glia.
Conclusions: :
The results suggest ganglion, amacrine and horizontal cells respond similarly but their responses vary between the rod and cone death period respectively. In contrast Muller glia and bipolar cells respond only during cone death
Keywords: retinal degenerations: cell biology • age-related macular degeneration • retinitis