Retinal Degeneration Promoted by Excessive Light: Role of the Glial Cells

Congreso; XXXIV Annual Meeting SAN 2019; 2019

Excessive exposure to artificial light affects the retina inducing photoreceptors cell death and leading to retinal degeneration (RD). Previously, we have established a novel model of RD by exposing adult rats to constant low intensity LED lights (200 lux). Using this model we showed that, after 5 days of exposure, the retina suffers important structural changes including photoreceptors cell death, opsins relocalization and increased oxidative stress. In the present work, we aimed to understand the role of neuroinflammation in the RD promoted by light excess; thus, we assessedthe time course of glia activation after 2, 4, 6 and 8 days of constant light exposure. Retinas were processed either for western blotting (WB) or IHC and we evaluated GFAP expression (Muller cells) and Iba-1 expression (microglia marker). After 4 days of exposure, we observed a significantincrease of active microglial cells (ameboid-shaped) and also, the active microglia relocated towards the outer retina (next to rods and cones nuclei). At the same time-point, we observed strong Mu¨ller cells activation compared to controls. Interestingly, WB analysis of the same retina revealedthe appearance of breakdown GFAP products (GFAP-BDPs), a proposed biomarker for Central Nervous System injury at two days exposure. Thus, our results indicate that glial activation precedes the photoreceptors cell death and suggest that an inflammatory response may be inducing cell-death pathways in our RD model.