Abstract
Purpose: :
To quantitatively elucidate the evolution of TUNEL-labeling, the end stage of the molecular biology of apoptosis after in vivo exposure to UVR.
Methods: :
Altogether, 16 Sprague Dawley rats were unilaterally exposed in vivo to UVR type-B (max at 302.6 nm with 5 nm full width at half maximum) for 15 minutes. Groups of 4 animals each received close to threshold dose (5 kJ/m2) of UVR-B. The animals were sacrificed at 1, 5, 24 and 120 hours post UVR-B exposure. For each animal, both eye globes were removed and frozen. The frozen eye was cryosectioned in 10 µm thick midsaggital sections. From each globe, 10 sequential sections were cut and section 1, 5, and 10 were mounted. Sections were TUNEL-labeled and counter stained with DAPI. For quantification of apoptosis, a fluorescence microscope was used. In each section, the number of lens epithelial nuclei and the number of TUNEL-positive epithelial nuclei was counted. The total number of TUNEL-positive epithelial nuclei for all three sections of one lens in relation to the total number of epithelial nuclei for all three sections of the same lens was compared between exposed and contralateral not exposed lens for each animal.
Results: :
The difference of the fraction of TUNEL-positive nuclei between exposed and contralateral not exposed lens increased gradually, peaked at 24 h after exposure, and then declined.
Conclusions: :
Close to threshold dose of UVR-300 nm induces TUNEL-labeling that peaks around 24 h after exposure to UVR-300 nm.
Keywords: apoptosis/cell death • cataract