RESUMEN
Objective To demonstrate if apoptosis is one of the mechanisms of siderotic retinopathy. Methods Autoclaved iron particles were implanted in the vitreous cavities of 32 eyes of SD rats. Glass chips were implanted in 10 control eyes. The experimental eyes were enucleated at various time intervals from days 1 to 15. Retinal degeneration was examined using the TdT mediated, dUTP biotin nick end labeling (TUNEL) method. Electrophoresis on agarose gel was used to detect internucleosomal DNA fragmentation. Results TUNEL positive nuclei were observed only in the outer nuclear layer beginning on day 2. The nuclei spread throughout the outer nuclear layer by the end of day 3. No TUNEL positive nuclei were observed in other layers throughout the experimental period. Analysis of DNA, extracted from the retinas by electrophoresis on agarose gel, revealed a typical ladder pattern of internucleosomal DNA cleavage in the experimental eyes. Conclusions Apoptosis of photoreceptors occurs at the early phase of iron induced retinopathy in the rats.