Apoptosis in UV-exposed rabbit corneas.
OBJECTIVE
Apoptosis was studied in rabbit corneas as a possible mechanism of cell death after photokeratitis induced by different UV wavelengths.


METHODS
Fourteen albino rabbit corneas were exposed to 280- and 310-nm UV radiation (UVR) in 10-nm full wavebands at doses that cause biomicroscopically significant keratitis (0.12 J/cm2 for 280 nm and 0.47 J/cm2 for 310 nm). Animals were killed 24 and 76 h after exposure. Corneas were processed for light and transmission electron microscopy and in situ end labeling of fragmented DNA by using a modification of the TUNEL technique.


RESULTS
Corneas exposed to 280-nm UVR showed TUNEL-positive staining only in epithelial cells and superficial keratocytes at 24 and 76 h after irradiation. Twenty-four hours after 310-nm UVR exposure, TUNEL-positive staining was present in the epithelial cells, keratocytes throughout the entire thickness of the central stroma, and in endothelial cells. Seventy-six hours after exposure to 310-nm UVR, keratocytes disappeared throughout the whole thickness of the damaged stroma. Only a few epithelial cells were TUNEL positive at that time. Transmission electron microscopy (TEM) verified the occurrence of apoptotic nuclei and cells.


CONCLUSIONS
Apoptosis appears to be a mechanism of corneal cell death after UVR. The 310-nm UVR caused more extensive damage to the corneal stroma and endothelium than did the 280-nm UVR.
Podskochy
A
A
St. Erik's Eye Hospital, Karolinska Institutet, Stockholm, Sweden.
Gan
L
L
Fagerholm
P
P
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D003315:Cornea / Q000528:radiation effects / Q000648:ultrastructure*; D003319:Corneal Stroma / Q000528:radiation effects / Q000648:ultrastructure; D004247:DNA / Q000032:analysis; D053938:DNA Fragmentation; D004195:Disease Models, Animal; D005260:Female; D005347:Fibroblasts / Q000528:radiation effects / Q000648:ultrastructure; D020287:In Situ Nick-End Labeling; D007634:Keratitis / Q000209:etiology / Q000473:pathology*; D011817:Rabbits; D014466:Ultraviolet Rays / Q000009:adverse effects*
D004247:DNA