Abstract
Purpose: :
Electroretinogram (ERG) is one of the most useful methods to measure the function of eye objectively and also used in diagnosis and prognosis of various retinal diseases. Among many animal models of retinitis pigmentosa (RP), rd1 mice have been most extensively studied animal. However, due to too rapid progress of retinal degeneration in rd1 mice, recently rd10 mice carrying same gene mutation (Pde6b) but slow onset of degeneration has advantage for testing therapeutic modalities. Before adapting rd10 mice as animal model for our electric stimulation modality, we try to confirm the period of prominent retinal degeneration in rd10 mice. Therefore, we compared the ERG responses from rd10 mice with that recorded from age-matched wild-type (wt) mice.
Methods: :
Postnatal 3 to 5 weeks mice were used both in wt mice (C57BL/6J) and rd10 mice (B6.CXB1-Pde6b/J). We used HMsERG which has mini-Ganzfeld stimulator appropriate for animal ERG recoding. ERG recordings were performed under dark-adapted (3 cd.s/m2, 10 cd.s/m2 with no background light) and light-adapted condition (3 cd.s/m2 following background light 30 cd.s/m2).
Results: :
In ERG recording, the amplitude and implicit time of a-wave and b-wave are the most important parameters. We compared the amplitude and implicit time of only b-wave in wt and rd10 mice since a-wave is almost disappeared in rd10 mice. Through all the postnatal ages from 3 to 5 weeks, b-wave amplitudes in rd10 mice (animal number; n=21) were significantly lower than that in wt mice (n=22) (17~162 μV vs. 320~480 μV: p<0.05). The implicit time of b-waves in rd10 mice were significantly slower than that in wild-type mice (55~73 ms vs. 96~151 ms: p<0.05). The most prominent changes happened in postnatal 3~4 weeks rd10 mice; b-wave amplitude decreased from 162.2 ± 56.4 μV to 40.0 ± 9.9 μV (p<0.05) and after 5 weeks, it decreased under 20.0 ± 7 μV.
Conclusions: :
Our results suggest that prominent retinal degeneration of rd10 mice happened in postnatal 3~4 weeks and degeneration completed by 5 weeks.
Keywords: electroretinography: non-clinical • retinal degenerations: hereditary • retinal connections, networks, circuitry