title: Morphological, functional and gene expression analysis of the hyperoxic mouse retina.
abstract: This study examined the impact of prolonged (up to 35 day) exposure to hyperoxia on the morphology and function of the retina, in the C57BL/6J mouse, as a basis for interpretation of gene expression changes. Mice of the C57BL/6J strain were raised from birth in dim cyclic illumination (12 h 5 lux, 12 h dark). Adult animals (90-110 days) were exposed to continuous hyperoxia (75% oxygen) for up to 35 d. Retinas were examined after 0 d (controls), 3 d, 7 d, 14 d and 35 d. Spatial and temporal patterns of photoreceptor death were mapped, using the TUNEL technique. Immunohistochemistry and a specific assay were used to assess the expression of a stress-related protein (GFAP) and the activity of key antioxidant enzymes (SOD). The dark-adapted flash electroretinogram was used to assess the function of rods and cones. RNA hybridized to Affymetrix Genechips was used to assess gene expression during the first 3 d of exposure. Photoreceptors were stable during the first 7 d exposure to hyperoxia, but thereafter showed progressive damage and degeneration, which began in a 'hot-spot' 0.5 mm inferior to the optic disc, then spread into surrounding retina. SOD activity was upregulated at 14 d, but not at earlier time points. GFAP expression was upregulated in Müller cells from 3 d. Rod and cone components of the ERG were supernormal at 3 d and 7 d, but then fell below control levels. Gene expression changes suggested possible mechanisms for this early supernormality of function. At 14 d exposure, damage to and death of photoreceptors were prominent and spreading, and function was correspondingly degraded. However at 3 d exposure, hyperoxia-induced supernormal functional responses in rods, while leaving their structure apparently undamaged. Variations in early (3 days) gene expression provide a partial insight into the mechanisms involved in this.
authors.affiliation: ARC Centre of Excellence in Vision Science, Research School of Biology, Australian National University, Australia. Riccardo.natoli@anu.edu.au
authors.forename: Riccardo
authors.initials: R
authors.lastname: Natoli
authors.forename: Krisztina
authors.initials: K
authors.lastname: Valter
authors.forename: Vicki
authors.initials: V
authors.lastname: Chrysostomou
authors.forename: Jonathan
authors.initials: J
authors.lastname: Stone
authors.forename: Jan
authors.initials: J
authors.lastname: Provis
mesh_terms: D000818:Animals; D016923:Cell Death; D003623:Dark Adaptation; D004596:Electroretinography; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D005904:Glial Fibrillary Acidic Protein; D018496:Hyperoxia / Q000201:enzymology / Q000235:genetics* / Q000503:physiopathology*; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010100:Oxygen / Q000633:toxicity; D020419:Photoreceptor Cells, Vertebrate / Q000201:enzymology / Q000473:pathology*; D012164:Retinal Diseases / Q000201:enzymology / Q000235:genetics* / Q000503:physiopathology*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D005904:Glial Fibrillary Acidic Protein; D009419:Nerve Tissue Proteins; C528900:glial fibrillary astrocytic protein, mouse; D013482:Superoxide Dismutase; D010100:Oxygen