Abstract
Purpose: :
We have previously reported an increase of albumin in retinas of glaucomatous monkey eyes, which was localized to the inner retina. The current study investigated whether the increased albumin found in glaucomatous monkey retinas also co-localized with cells exhibiting increased oxidative damage, as indicated by increased nitrotyrosine immunoreactivity.
Methods: :
Posterior segments from monkeys with unilateral experimental glaucoma were fixed in 4 % paraformaldehyde in phosphate buffer. Retina samples, 1mm in diameter, were taken from the temporal inferior region of each eye, 5mm from the fovea, and vibratome sections were cut. The sections were immunolabeled with a monoclonal antibody to nitrotyrosine and a polyclonal antibody to human serum albumin. Antibody binding was visualized with a Cy3 and a Cy5 conjugated secondary antibody. Images of retina from the laser treated right eye and the control left eye of each monkey were taken using identical parameters with a Zeiss confocal microscope.
Results: :
Control retinas exhibited light immunoreactivity for nitrotyrosine in the inner retina. In comparison, many more of the cells in the inner-most part of the inner nuclear layer and the inner plexiform layer of glaucomatous retinas were heavily labeled for nitrotyrosine. Albumin immunoreactivity co-localized with nitrotyrosine positive cells in the inner nuclear layer and with cell processes in the inner plexiform layer. Co-localization of nitrotyrosine and albumin was also detected in the region of the ganglion cell/nerve fiber layer in the absence of most ganglion cells.
Conclusions: :
The co-localization of albumin with nitrotyrosine indicates a link between accumulation of albumin and oxidative damage. Since albumin is a major antioxidant, its enhanced presence in nitrotyrosine positive regions suggest that increased albumin in glaucomatous retinas may be attributed to increased oxidative stress. Albumin may provide cell protection against oxidizing species in the inner retina, but the amount of albumin maybe insufficient to protect retinal ganglion cells.
Keywords: oxidation/oxidative or free radical damage • retina • stress response