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Dana K. Vaughan, Sylvie F. Coulibaly, Ruth M. Darrow, Daniel T. Organisciak; A Morphometric Study of Light-Induced Damage in Transgenic Rat Models of Retinitis Pigmentosa. Invest. Ophthalmol. Vis. Sci. 2003;44(2):848-855. doi: https://doi.org/10.1167/iovs.02-0709.
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purpose. To determine relative susceptibility to, and regional variation of, light-induced retinal damage in two rhodopsin-mutant rat models of retinitis pigmentosa, using slow- and fast-degenerating lines.
methods. Transgenic S334ter (lines 4 and 9) and P23H (lines 2 and 3) rats were reared in dim cyclic light or darkness and then exposed to intense green light for 1 to 8 hours. Sections along the vertical meridian were collected for retinal morphology and photoreceptor morphometry 2 weeks later. Unexposed transgenic and normal Sprague-Dawley rats served as the control. Mean outer segment lengths and outer nuclear layer thicknesses were analyzed as a function of position along the vertical meridian and as averages across that vector.
results. Rapidly degenerating S334ter-4 retinas, reared in dim cyclic light, exhibited no light-induced damage, whereas retinas in the other sublines sustained damage within a sensitive region in the superior hemisphere. Light-induced damage always involved loss of outer segment membrane and photoreceptors. In some cases, the retinal pigment epithelium and inner nuclear layer were also affected. Potentiation of light-induced damage by dark-rearing was increased by at least a factor of three, and in some sublines the sensitive region was enlarged to include the entire vertical meridian.
conclusions. A complex pattern of light-induced damage outcomes was identified in S334ter (sublines 4 and 9) and P23H (sublines 2 and 3) rats. The relative susceptibilities of each subline to damage by light were different, even within the same transgene, but consistent factors included a sensitive region in the superior hemisphere and potentiation by dark-rearing.
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