Selective photoreceptor damage in albino rats using continuous blue light. A protocol useful for retinal degeneration and transplantation research.
OBJECTIVE
To develop a retinal degeneration model with selective photoreceptor loss and RPE sparing, to be used as recipient for evaluating retinal transplants.


METHODS
Albino rats were exposed to blue light, continuously, for 1-7 days (24-168 h) in a specially designed cage. Eyes were histologically analyzed at periods between 2 h and 8 months after the light exposure. Electroretinograms (ERGs) were recorded from some rats at 12-216 days after exposure. Using behavioral methods, visual thresholds of some rats were determined before exposure and re-measured between 18 and 52 days following exposure.


RESULTS
Apoptotic nuclei appeared exclusively in the photoreceptor layer after 1-5 days exposure to blue light. Light microscopy revealed that 2-4 days of light exposure reduced the outer nuclear layer (normally eight to ten rows) to 1 row of cells in the central retina and to two to three rows in the periphery, both in the superior and the inferior retina. Average ERG a- and b-wave amplitudes of light-damaged rats were both reduced by about 98%. Visual performance in the behavioral test was substantially impaired.


CONCLUSIONS
Continuous exposure of albino rats to moderate blue light for 2-5 days selectively eliminates most of the photoreceptors while leaving the RPE initially intact.
Seiler
M J
MJ
Department of Ophthalmology & Visual Sciences, University of Louisville, KY 40202, USA. mjseil@athena.louisville.edu
Liu
O L
OL
Cooper
N G
NG
Callahan
T L
TL
Petry
H M
HM
Aramant
R B
RB
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D004596:Electroretinography; D005260:Female; D006085:Graft Survival / Q000528:radiation effects; D020287:In Situ Nick-End Labeling; D008027:Light / Q000009:adverse effects*; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology / Q000528:radiation effects*; D010857:Pigment Epithelium of Eye / Q000528:radiation effects / Q000637:transplantation; D011833:Radiation Injuries, Experimental / Q000209:etiology* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012162:Retinal Degeneration / Q000209:etiology* / Q000473:pathology; D013997:Time Factors