Abstract
Purpose: :
Blue light exposure in rodents is a model for investigating the morphological and physiological changes that occur in response to oxidative stress. In an attempt to further characterize this model in mice, we investigated how variation in both exposure time and animal strain affect the structure, function, and molecular profile of the retina.
Methods: :
Nine-week-old C57Bl/6 and Balb/c mice were dark adapted prior to being treated with between 1 and 50 hours of blue light exposure (420nm, 550 lux). Retinal function was quantified by electroretinography (ERG) after light exposure. A-wave and b-wave amplitudes were monitored in response to a series of flashes ranging from -4 to 1.8 log•scot•cd•s•m-2. Morphological alterations were assessed with optical coherence tomography (OCT) while molecular changes were quantified by Western blot and immunofluorescence (IF).
Results: :
Balb/c mice are highly sensitive to blue light exposure, exhibiting an exposure-time dependent decrease in retinal function as measured by ERG. A-wave and b-wave amplitudes were significantly reduced (36% and 42%, respectively) with 1.8 log flashes after as little as 2 hours of light exposure (p<0.001). Balb/c mice also exhibited significant thinning of the photoreceptor layer as measured by OCT (-64%). Eye tissue of these blue light exposed Balb/c mice also displayed autophagy specific marker as measured by both Western blot and IF. In contrast, C57Bl/6 mice were highly resistant to light exposure. These animals exhibited no retinal abnormalities by either ERG or OCT.
Conclusions: :
We have shown that blue light exposure in Balb/c mice inhibits retinal function as measured by electroretinography. OCT results indicate that the source of this retinal dysfunction is likely preferential damage to the photoreceptors. Both IF and Western blot results support these findings and indicate that the damage involves autophagy.
Keywords: oxidation/oxidative or free radical damage • electroretinography: non-clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)