Abstract
Purpose: :
To study the effect of blue filters of specific wavelengths on ERG responses and circadian activity (CA) in the pigmented and albino mouse. Blue light has been shown to induce a retinal damage in the albino mice, which determines significant decrease of retinal light responses. As an attempt to reduce light damage, we have tested the protective effect of light filters in the 400-500 wavelength range on light sensitivity. However, maximum sensitivity of ipRGCs also range in the blue spectrum. Since ipRGC seem to be important for the animal circadian activity, we wonder if blue filters may also affect the circadian activity in animals exposed to light damage.
Methods: :
C56BL6J strain and NMRI albino mice were used for experiments. Light damage was induced in experimental mice by the use of 60h of continuous white light of high intensity (5000 lux). Flash ERG responses were recorded under light and dark adaptation in all animals just before light damage and 5, 12 and 20 days after finishing light exposure. Similar experiments were performed in a second series of animals after filtering the damaging light with sort wavelength light filters. ERG amplitudes from different experimental conditions were compared. CA of albino and pigmented mice were tested by the use of wheel activity cages. CA was investigated in control animals and test mice just after finishing the light induced damaged, with and without blue filters. In a final series of experiments, we compare the CA in control pigmented mice and the Rd10 mouse model of retina degeneration, which comprise ipRGCs as the only photosensitive cells in their retinas by 60 postnatal days.
Results: :
Our experiments show that blue filters permit a significant reduction of the light induced retinal damage in albino mice. No effect of the blue filter was observed in pigmented mice. By the use of the different mouse models, we observed that ipRGCs are sufficient to maintain the light synchronization of circadian activity that is not affected by the use of blue filters.
Conclusions: :
The functional role of melanopsin-expressing cells on light mediated circadian activity is not conditioned by the presence of light filters of short wavelengths. Blue filters support significant benefit for protection of light induced damage.
Keywords: electroretinography: non-clinical • radiation damage: light/UV • circadian rhythms