Abstract
Purpose: :
The exposure to high light levels causes degenerative changes in the mammalian retina, and seems to be involved in the pathophysology of age-dependent macular degeneration and retinitis pigmentosa. However, it still remains unclear which part of the visual spectrum is responsible for retinal damage although several evidence suggest that "blue light" is the one responsible for these noxious effects. In the present study we investigated the effects of long-term exposure to light on the retina and the protective effects of intraocular lenses designed to filter parts of the visual spectrum. Adult pigmented rabbits with yellow intraocular lenses were exposed to circadian white light for different periods; animals with intraocular transparent lenses were used as a control.
Methods: :
Total RNA was prepared from isolated retinas from the different groups of animals. Relative mRNA levels for c-fos, c-jun, and different apoptosis related genes (bcl-2, bcl-XL, bax, bad, caspase-1, caspase-3) were determined semiquantitatively using RT-PCR and Western-blot. Furthermore, we analyzed by Western-blot the changes in some calcium-binding proteins (calmodulin, calbindin D28k, parvalvumin, calretinin).
Results: :
The expression of these genes was not affected by light exposure, although a slight long-term upregulation of c-fos and of c-jun was observed. Interestingly caspase-3, but not caspase-1, was upregulated. No changes were observed in the other apoptosis-related genes analyzed. Western-blot results paralleled those of PCR. On the other hand, there is a general decrease in the calcium binding proteins investigated. Interestingly, all these changes were reverted by intraocular lenses filtering the blue portion of the visual spectrum, whereas the other lenses were without effect in the expression of these genes and related proteins
Conclusions: :
Present results demonstrated that Ca++-related and apoptosis-related changes induced by light in the retina might be reverted and/or prevented by intraocular lenses filtering blue light.
Keywords: age-related macular degeneration • gene/expression • intraocular lens