Gene expression microarray analysis of early oxygen-induced retinopathy (OIR)

Different inbred strains of rats differ in their susceptibility to OIR, an animal model of human retinopathy of prematurity. We examined gene expression profiles in Fischer 344 (F344, resistant to OIR) and Sprague Dawley (SD, susceptible to OIR) rats at the early time point of day 3 to identifying gene pathways related to the underlying genetic cause of phenotypic differences between strains. To examine gene expression changes in rats strains which are resistant and susceptible to OIR, four different experimental conditions were analysed: F344 cyclic hyperoxia (O2) exposed, F344 room air (RA) exposed, SD O2 exposed and SD RA exposed. A minimum of two samples of pooled RNA, comprising of 3 individual rats from 2 separate litters, was used for each experimental condition. Pooled RNA from different rats were used as biological replicates. An additional sample for F344 O2 and SD RA rats was included on the basis of the principal components analysis from the initial 8 samples. Pooled RNA from age-matched room air-exposed rats were used as controls.