Characterization of the Light-Sensitive Arciform Region in the Albino Rat Retina

Abstract

Purpose: : To determine in albino rats the existence of the arciform area of heightened light sensitivity and to investigate the characteristics of light-induced retinal degeneration in the albino rat retina in order to compare the findings with those reported before for the pigmented rat retina.

Methods: : We have exposed albino Sprague-Dawley and pigmented Lister-Hooded and non-dystrophic Royal College of Surgeons rats to continuous light during different time periods. The left pupil was dilated prior and during light exposure. The animals were processed between 0 days and 3 months after light exposure. Before processing, the eye fundus was inspected and type I horseradish peroxidase (HRP) was injected into the femoral vein to label the retinal vessels or Fluoro-Gold was applied to the superior colliculi to label the retinal ganglion cells. Retinas were dissected as whole mounts or processed for cross-sections, reacted for HRP demonstration or incubated with different antibodies.

Results: : Both albino and pigmented rats presented, immediately after light exposure, a distinct arciform area of retinal degeneration in the superotemporal retina that showed HRP leakage. The characteristics of this area in albino rats varied with time of exposure and pupillary dilation. However, photoreceptor degeneration was observed all throughout the retina and all the retinal layers were affected with time.

Conclusions: : Although albino rats are more sensitive to light than pigmented rats, they show a light-sensitive arciform area and similar evolution of the light-induced retinal degeneration.

Keywords: retinal degenerations: cell biology • radiation damage: light/UV • apoptosis/cell death