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M.A. Mandal, R.A. Bush, P.A. Sieving, R. Ayyagari; Early response of retina to damaging light – a microarray analysis . Invest. Ophthalmol. Vis. Sci. 2004;45(13):684.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To better understand the mechanism of light–induced retinal damage and to identify the early events leading to photoreceptor cell death, the gene expression profile immediately after exposure to constant bright light was studied in rat retina. Methods: Male albino Harlan Sprague Dawley rats acquired at 7 weeks and reared in 50 lux cyclic light to 10–weeks were exposed to damaging light of 2000 lux for 24 hours. This exposure was previously shown to produce substantial photoreceptor cell death. Retinas were dissected immediately after the damage and pooled from 3 animals. Retinas from litter mate controls, raised in the same conditions and not exposed to damaging light, were collected at the end of the dark cycle. RNA isolated from triplicates of control and light–damaged groups were used to make biotinylated cRNAs for gene chip hybridization. Each labeled RNA was hybridized to GeneChip Arrays (Rat Genome U34A) representing 8800 genes from Affymetrix. Scanning of probe arrays and data analysis was performed according to standard Affymetrix protocols. Results: Out of 8800 genes in the probe array, analysis could detect the presence of 38–42% genes in 3 independent sets of hybridization reaction. Among the detected numbers, the expression of 15–21 % genes were changed (> 2 fold) in light damaged retinas compared to controls: 8.7–12.2 % were increased and 6.2–9.2 % were decreased. Among the genes showing highly significant changes (> 4 fold), we identified transcription of 35 genes was turned on and 40 other genes was enhanced in response to damaging light. On the other hand transcription of 30 genes was turned off and repressed significantly for an additional 38 genes. The biological processes they are associated with include oxidative stress response, cellular defense response, stimulation for DNA damage and cell death, neuronal cell function, carbohydrate and lipid metabolism, and cytoskeleton generation. We also analyzed the variation in the expression of the representative photoreceptor genes present in the commercial GeneChip. Conclusions: Intense light exposure significantly changes the gene expression profile of retina. Global gene expression analysis can help in delineating the initial events and the following cascade associated with light induced retinal cell death.
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