Effect of Constant Low Light Exposure on Rat Retina: A Model of Retinal Degeneration

BENEDETTO, MARIA MERCEDES; QUINTEROS QUINTANA, MARIA LUZ; GUIDO, MARIO EDUARDO; CONTIN, MARIA ANA

Encuentro; XXIX ANNUAL MEETING AND SAN-ISN SMALL CONFERENCE AND COURSE; 2014

The retina is part of the central nervous system adapted to capture light photons and transmit the information to brain. It has been shown that light in excess may cause retinal degeneration (RD) or accelerate genetic retinal disorders; however, the mechanism of retinal cell death is not well characterized yet. In order to study the process of RD produced by low light, Wistar rats were exposed to constant white light of 200 lux intensity from 1 to 7 days. Control animals were kept in light (200 lux) / dark (0 lux) cycles 12hs /12hs or constant darkness . We found that the exposure to constant light reduces photoreceptors cells only after seven days of exposure (ONL reduction). We also demonstrated that photoreceptor death was by an apoptotic mechanism caspase-3-independent. The analysis of rhodopsin demonstrated that both, the expression and the location in the outer segment was not altered prior to photoreceptor death, but it was more phosphorylated in ser334 in relation to control animals. Because oxidative stress is considered a major cause in certain RD, reactive oxygen species were measured using 2?7?-dihydroethidium (DHE) and CAT activity was analyzed too. Both results showed no significant differences between experimental groups. Based on these results we conclude that retinal damage by constant low light exposure could be an useful model for studying the mechanisms involved in phototransduction defects.