Differences in photoreceptor sensitivity to oxygen stress between Long Evans and Sprague-Dawley rats.
OBJECTIVE
To examine the susceptibility of photoreceptors to hyperoxic stress in two rat strains, the pigmented Long Evans (LE) and the albino Sprague-Dawley (SD).


METHODS
Adult LE and SD rats were exposed to hyperoxia (75% oxygen) for 14 days. Retinas were assessed for electroretinogram (ERG) responses, cell death, and expression of a retinal stress factor.


RESULTS
In the LE strain, exposure to hyperoxia significantly reduced amplitudes of rod a-wave, rod b-wave and cone b-wave components of the ERG, and caused a 55-fold increase in photoreceptor cell death rates, and an upregulation of GFAP expression. In the SD strain, hyperoxic exposure had no measurable effect on the ERG response of rods or cones, and resulted in a modest (5-fold) increase in the rate of photoreceptor cell death.


CONCLUSIONS
In LE and SD strains, hyperoxia induces cell death specific to photoreceptors. The effect is an order of magnitude more severe in the pigmented LE strain suggesting a strong genetic component to oxygen sensitivity, as reported previously between the albino Balb/C and pigmented C57BL/6 strains of mice.
Research School of Biological Sciences, The Australian National University, Canberra, Australia. vicki.chrysostomou@anu.edu.au
Vicki
V
Chrysostomou
Jonathan
J
Stone
Krisztina
K
Valter
D000818:Animals; D004596:Electroretinography; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D018496:Hyperoxia / Q000503:physiopathology; D020287:In Situ Nick-End Labeling; D051379:Mice; D010100:Oxygen / Q000633:toxicity*; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D051381:Rats; D020318:Rats, Long-Evans; D017207:Rats, Sprague-Dawley; D017949:Retinal Cone Photoreceptor Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D017948:Retinal Rod Photoreceptor Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013312:Stress, Physiological / Q000187:drug effects*
D005904:Glial Fibrillary Acidic Protein; D010100:Oxygen