Abstract
Purpose:
It is known that high light exposition induces retinal damage in healthy individuals. It has been shown that the retinal damage induced by short wavelength (blue) light is stronger than the one produced by other wavelengths. We have recently shown that blue-blocking filter protects the retina to light-induced damage in healthy mice. In this study we tested whether the blue-blocking filter is able to decrease retinal degeneration in the Rd10 animal model.
Methods:
Electroretinogram (ERG) responses were recorded in 30 days old Rd10 mice housed in three different experimental conditions. Animals (n=10) from group one (Control) were housed since birth date in 12:12 h light/dark cycles; fluorescent light (60 lux) was used during light periods. Animals (n=10) from group two (Dark) were housed in absolute darkness since birth date. Animals (n=10) from group three (Filter) were housed in 12:12 h light/dark cycles like in the Control group; in the Filter group, a blue-filter (Roscolux#312) was used to protect the animals from the fluorescent light. Histological analysis was performed in retinal sections from the three animal groups for comparison.
Results:
The ERG experiments show that animals from the Control group have an almost flat light response (scotopic b-wave maximal amplitude of 15.2±2.3 mV and photopic b-wave of 2.7±1.3 mV). Histological cell labeling shows the dramatic decrease in photoreceptors, estimated by counts of cell bodies located in the outer nuclear layer (ONL). Data obtained from animals of the Dark group show significant remaining of ERG waves amplitudes (scotopic b-wave maximal amplitude of 147.2±12.5 mV and photopic b-wave of 63.8±5.6 mV). Histological labeling showed that the number of remaining cells in the ONL was significant larger that in the Control group. Data obtained from animals of the Filter group did not show significant differences with the Control group (scotopic b-wave maximal amplitude of 12.6±2.1 mV and photopic b-wave of 3.2±1.4 mV). The number of cells remaining in the OPL was also very low.
Conclusions:
Our work demonstrates that dark rearing protects the photoreceptors in the Rd10 mouse model of retinal degeneration. However, the photoreceptor damage observed in Rd10 mice reared under dark/light cycles cannot be prevented by filtering the short wavelength light.