Abstract
Purpose: :
Penetration of light in the eye is known to be a significant contributory factor in the genesis of human senile cataracts. Studies from this and other laboratories have strongly suggested that this is due to intraocular photocatalytic generation of superoxide and its derivatization to other reactive oxidants inflicting oxidative damage to the tissue and eventual cell death. Since caffeine is an effective scavenger of ROS, the objective of this study was to determine if it could attenuate the UV stress induced apoptosis.
Methods: :
Freshly isolated mice lenses were incubated for 5 hrs in Tyrode without and with 2.5 mM caffeine, in dark and under UV(302nm,0.6mW/cm2). They were then fixed in PBS buffered 10% formalin,paraffin-embedded, sectioned and then stained with TUNEL and DAPI following the protocols and reagents obtained from Roche (Cat. # 11 684 795 910) and Invitrogen (Cat. # p36935), respectively.
Results: :
As expected, UV exposure led to an extensive induction of apoptosis apparent by strong fluorescence of lens cells by TUNEL staining and by aberrant migration of such cells to posterior subcapsular region. In addition, there was also a significant loss in the number of epithelial cells from its anterior surface. As hypothesized, such apoptotic effects of UV were nearly abolished by the presence of caffeine in the medium, the results being similar to that in dark where the cells remained normal. Results with DAPI were similar.
Conclusions: :
The findings strongly suggest that caffeine is highly effective in protecting the lens against UV induced apoptosis. Based on the fact that caffeine is a potent scavenger of ROS, it is suggested that the observed anti-apoptotic effects of caffeine are attributable to its antioxidant effects.
Keywords: antioxidants • apoptosis/cell death • oxidation/oxidative or free radical damage