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

BENEDETTO, MARÍA MERCEDES; QUINTEROS QUINTANA, MARIA LUZ; MARIA ANA CONTIN

Córdoba

Congreso; Sociedad Argentina de Investigación en Neurociencias (SAN).; 2014

Sociedad Argentina de Investigación en Neurociencias (SAN).

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 (LD) or constant darkness (DD).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 apoptotic caspase-3-independent mechanism. The analysis of rhodopsin demonstrated that both, the expression of protein and the location in 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 using 2'7'-dihydro ethidium (DHE) and CAT activity were measured. Both results showed no significant differences between experimental groups indicating a no oxidative stress in the first days of degeneration.Based on these results we conclude that retinal damage by constant low light exposure could be a useful model for studying the mechanisms involved in phototransduction defects.