c-Fos protein in photoreceptor cell death after photic injury in rats.
OBJECTIVE
To examine the involvement of c-Fos protein in light-induced photoreceptor cell death in rats.


METHODS
Thirty-two Lewis albino rats were exposed to green fluorescent light (480-520 nm) of 300 to 320 foot-candles (3228-3443.2 lux) for 3 hours, allowed to recover in the dark, and euthanatized at 0, 1, 3, 6, 12, 24, or 96 hours after light exposure. c-Fos was detected immunohistochemically and nicked DNA by in situ TdT-dUTP terminal nick-end labeling (TUNEL). Double labeling of c-Fos and DNA nicks was also performed.


RESULTS
There was a time-dependent change in the number of c-Fos-positive photoreceptor nuclei after light injury, which paralleled the change in the number of TUNEL-positive nuclei. The temporal and spatial appearance of these nuclei also matched the appearance of pyknotic nuclei of the outer nuclear layer. Double-labeling study revealed that some c-Fos-positive nuclei were also TUNEL-positive nuclei.


CONCLUSIONS
There was an acute accumulation of c-Fos protein in photoreceptors associated with cell death. This study further supports other studies showing that c-Fos is linked to apoptotic photoreceptor cell death.
Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong.
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HK
Poon
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Tso
T T
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Lam
D000818:Animals; D017209:Apoptosis; D004247:DNA / Q000032:analysis; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D020287:In Situ Nick-End Labeling; D008027:Light / Q000009:adverse effects*; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism* / Q000473:pathology / Q000528:radiation effects*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D011833:Radiation Injuries, Experimental / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D011917:Rats, Inbred Lew; D012164:Retinal Diseases / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D013997:Time Factors
D016760:Proto-Oncogene Proteins c-fos; D004247:DNA