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Emilie Picard, Marianne Berdugo, Mohamed El Sanharawi, Jean-Claude Jeanny, Yves Courtois, Francine F. Behar-Cohen; Transferrin Delivery In The Eye Protects Photoreceptors From Light-Induced Retinal Degeneration. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6427.
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Age-Related Macular Degeneration is associated with iron accumulation due to defects in its homeostasis metabolism, similarly to what is observed in several models of retinal degeneration (rd10 mice or RCS rats). We have previously showed that light exposure induced an early mobilization of proteins regulating iron metabolism in the retina. Recently, we have showed that transferrin (Tf), either intraperitoneally injected or genetically produced, protects against photoreceptors death due to genetic mutations (rd10 mice and RCS rats). Here, we analyze the effect of Tf on a model of light-induced photoreceptors degeneration.
Retinal degeneration was induced in 6-week-old Wistar rats by intense green light (4500 lux) for 12 hours, followed by one week of cyclic light. To test the effects of Tf, human Tf (hTf) was intravitreally injected into anesthetized rats prior illumination. Before sacrifices, in vivo exploration were done by Optical Coherence Tomography (OCT) and Electroretinography (ERG; scotopic and photophic recordings). Then eyes were fixed and sections of their retinas were analyzed to measure outer nuclear thickness. Levels of human Tf and iron in retina were respectively evaluated by ELISA and colorimetric methods.
Intravitreal injection of human Tf protects the retina (especially photoreceptors) against the deleterious effects of light. Preservation of photoreceptors layer thickness is proportional to the amount of hTf delivered. These results are confirmed by OCT and ERG recordings. The amount of total iron is increased in retinas exposed to light. Nevertheless, the iron level is reduced in rats injected with hTf compared to BSS. Injected human Tf is still present in the retina 7 days after injection.
Tf injected directly into the eye has a potent protective effect on the neurodenegerative process induced by intense light. This effect seems to be due to the iron chelating effect of Tf.
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