Protein nitration: Is it part of the oxidative stress associated with light induced retinal damage?

SOLIÑO M; MANTA LLOPART N; PUSTOVRH C; LOPÉZ EM; LOPÉZ-COSTA JJ

Huerta Grande

Congreso; XXVI Congreso Anual de la Sociedad Argentina de Neurociencias; 2011

Sociedad Argentina de Neurociencias

Continuous illumination (CI) of the retina induces the degeneration of photoreceptors. Electron Paramagnetic Resonance demonstrated an increase of NO signal in CI retinas peaking at 24 hs while Western blot (WB) showed a peak of iNOS expression. Our hypothesis is that NO may be one of the free radicals involved in the oxidative stress induced by CI, and its increase could be involved in photoreceptor degeneration. In order to study the oxidative effect of NO in retinal tissue we determined the nitration of proteins by immunocytochemistry (ICC) and WB. Sprague Dawley rats were continuously illuminated with white light (12000 lux) for 24 hs, 48 hs, 5 and 7 days while control rats (CTL) were maintained at light/dark cycles of 12/12 h. The eyes of CTL and CI rats were fixed and processed with the PAP ICC technique using a nitrotyrosine (Ntyr) antibody. Other eyes were processed by WB and densitometry was performed using Image J Software. Nitrotyrosine immunoreactivity was observed in Inner Nuclear Layer (INL) and Ganglion Cell Layer (GCL) in CTL rats. After CI, Ntyr immunoreactivity was observed in Outer Nuclear Layer (ONL) as well as in INL and GCL. WB analysis showed a band pattern that differed among control, 5 and 7 days of CI. The observed results showed a change of nitration patterns in CI rats both by ICC and WB. It may be that the increase of NO nitrates tyrosine residues in proteins which alter their structures and functions leading, probably with other free radicals, to the oxidative damage that leads to retinal degeneration. Sprague Dawley rats were continuously illuminated with white light (12000 lux) for 24 hs, 48 hs, 5 and 7 days while control rats (CTL) were maintained at light/dark cycles of 12/12 h. The eyes of CTL and CI rats were fixed and processed with the PAP ICC technique using a nitrotyrosine (Ntyr) antibody. Other eyes were processed by WB and densitometry was performed using Image J Software. Nitrotyrosine immunoreactivity was observed in Inner Nuclear Layer (INL) and Ganglion Cell Layer (GCL) in CTL rats. After CI, Ntyr immunoreactivity was observed in Outer Nuclear Layer (ONL) as well as in INL and GCL. WB analysis showed a band pattern that differed among control, 5 and 7 days of CI. The observed results showed a change of nitration patterns in CI rats both by ICC and WB. It may be that the increase of NO nitrates tyrosine residues in proteins which alter their structures and functions leading, probably with other free radicals, to the oxidative damage that leads to retinal degeneration. Sprague Dawley rats were continuously illuminated with white light (12000 lux) for 24 hs, 48 hs, 5 and 7 days while control rats (CTL) were maintained at light/dark cycles of 12/12 h. The eyes of CTL and CI rats were fixed and processed with the PAP ICC technique using a nitrotyrosine (Ntyr) antibody. Other eyes were processed by WB and densitometry was performed using Image J Software. Nitrotyrosine immunoreactivity was observed in Inner Nuclear Layer (INL) and Ganglion Cell Layer (GCL) in CTL rats. After CI, Ntyr immunoreactivity was observed in Outer Nuclear Layer (ONL) as well as in INL and GCL. WB analysis showed a band pattern that differed among control, 5 and 7 days of CI. The observed results showed a change of nitration patterns in CI rats both by ICC and WB. It may be that the increase of NO nitrates tyrosine residues in proteins which alter their structures and functions leading, probably with other free radicals, to the oxidative damage that leads to retinal degeneration.