mdx(Cv3) mouse is a model for electroretinography of Duchenne/Becker muscular dystrophy

Purpose. To identify an animal model for the abnormal scotopic electroretinogram found in a majority of Duchenne and Becker muscular dystrophy patients. Methods. Ganzfeld electroretinograms were recorded in dark-adapted normal C57BL/6 mice, and two strains of mice with different X- linked muscular dystrophy mutations (mdx and mdx(Cv3)). Responses for the right eye were averaged and the amplitudes and implicit times of the a-wave and b-wave were measured. The electroretinogram was digitally filtered to extract the oscillatory potentials. Statistical analyses included one-way analysis of variance and the Scheffe S test. Results. While the electroretinogram in mdx was normal, in mdx(Cv3) the scotopic b-wave was markedly reduced and the oscillatory potentials were delayed, similar to changes observed in Duchenne and Becker muscular dystrophy patients. Some of the mdx(Cv3) animals demonstrated negative configuration electroretinograms, with the b-wave amplitude reduced compared to that of the a-wave. Conclusions. Abnormalities found in the electroretinograms of Duchenne and Becker muscular dystrophy patients led to the identification of dystrophin in human retina and the discovery that dystrophin is required for normal retinal electrophysiology. These results indicate that mdx(Cv3) is a model for elucidating the role of dystrophin in retina and suggest that dystrophin isoforms, consisting of only the C-terminal domains of the full-length protein, may be important to the development of normal retinal electrical potentials.