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J. Chen, S. Seal, J.F. McGinnis; Inorganic Nanoparticles Prevents Light–Induced Blindness in Rats . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4848.
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We previously showed, using cultured retinal neurons, that inorganic nanoparticles increased longevity and decreased intracellular reactive oxygen species (ROS). In this study, we examined the ability of these nanoparticles to protect photoreceptor cells in vivo from light–induced degeneration, a model system known to involve production of ROS.
Nanoparticles, 2µl of 3 different concentrations, were injected into the vitreous of adult rat eyes 3 days before, or 2hrs after, the exposure of the animals for six hours to 2700 Lux of light. Rats were returned to normal cyclic light for seven days, then evaluated for visual function by scotopic electroretinography (ERG), and subsequently by morphometric analysis of histological sections of the eyes. TUNEL assays were used to visualize apoptotic cells.
The intravitreal injection of nanoparticles, both before and after light exposure, showed dramatic protection in a dose dependent manner. Morphologically, the nanoparticles provided protection throughout the retina, retaining essentially all rows of photoreceptor nuclei and preserved the structure of the outer and inner segments. Functionally, the nanoparticles prevented any significant loss in the A– and B–wave amplitudes of the ERG both before and after light exposure. In addition, the saline injected eye showed numerous apoptotic cells whereas the nanoparticle injected eye showed none.
The nanoparticles prevent the actual loss of photoreceptor cells as observed morphologically and completely protected the functional activity when injected prior to light–exposure. These data demonstrate that the nanoparticles can prevent light–induced blindness and that they are effective even after exposure to light. They suggest that the nanoparticles may be effective in preventing blindness due to any disease in humans which proceeds through the production of ROS.
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