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X. Dai, B. Lei, B. Chang, W. W. Hauswirth, J. Qu, J. Pang; Electroretinograms of the rd12 Mouse, a Model of Leber Congenital Amaurosis Caused by a Mutation in RPE65 Gene. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3600.
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© ARVO (1962-2015); The Authors (2016-present)
Leber Congenital Amaurosis (LCA) caused by RPE65 mutations leads to early onset of blindness. The rd12 mouse, a naturally occurring animal model of LCA with an Rpe65 mutation, exhibits residual photoreceptor functions which may be capable of translating into useful visual signals. To investigate the origin of those signals, normal C57BL/6J mice and rd12 mice at postnatal day 14 (P14) when both rod and cone morphologies are amlost normal were tested with flicker electroretinograms (ERGs) elicited at different stimulus frequencies and intensities.
P14 C57BL/6J and rd12 mice were anesthetized and their pupils were dilated before recording. Dark-adapted ERGs were recorded with a serial of stimulation lights (intensity covers 4 log units). Dark- and light-adapted flicker ERGs were elicited with eight stimulus frequencies (5, 10, 15, 20, 25, 30, 35 and 40Hz) at two intensity levels. The dim stimulus (-3.0 Log cd·s·m-2) activates only rods and the bright stimulus (+0.5 Log cd·s·m-2) activates both rods and cones. Light-adapted ERGs were elicited under a steady background illumination (30 cd/m2).
In C57BL/6J mice with dim light stimuli, dark-adapted flicker ERGs were recorded with low frequency stimuli (5~20Hz), but not with high frequency stimuli (25~40Hz). With bright stimuli, flicker ERGs were observed at all eight frequencies. These cone-driven flicker ERG responses were confirmed in light-adapted normal mice with 5~40Hz stimuli. In rd12 mice with dim light stimuli, no dark-adapted flicker responses were seen at any of the eight frequencies. With bright stimuli, dark-adapted flicker responses were recorded at 5~20Hz, but not at 25~40Hz. With the same bright stimuli, light-adapted flicker ERGs were observed when the frequencies were at 5~20Hz, whereas no flicker signals were recorded at 25~40Hz.
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