The FVB Background Does Not Dramatically Alter the Dystrophic Phenotype of Mdx Mice

Discussion To meet the practical needs of our transgenic studies, we crossed the BL10-background mdx mice with FVB/NJ mice. Recent studies suggest that the so-called “wild type” inbred mice may actually carry various changes in their genome. For example, the commonly used A/J mice were recently show to display progressive muscular dystrophy due to a mutation in the dysferlin gene 24. The FVB strain was also found to carry mutations in several genes of the visual system 25. It is thus important to determine whether the FVB background alters the dystrophic phenotype of the original mdx mice. After seven generations of backcross, we obtained white mdx/FVB mice. These mice showed classic dystrophic changes including elevated serum CK, myofiber centronucleation, muscle inflammation and fibrosis, force reduction and enhanced sensitivity to eccentric contraction injury. In young adult mdx mice, the specific twitch and tetanic force for EDL muscle range from 26.6±1.2 to 29.0±1.5 and 129.6±10.5 to 138.5±5.6 mN/mm2, respectively. In young adult C57Bl/10 (BL10) mice, the specific twitch and tetanic force for EDL muscle range from 33.2±1.8 to 46.5±3.7 and 185.4±5.7 to 245.0±1.4 mN/mm2, respectively 12,26-28. Muscle force drops from 100% (baseline) to 53.5-29.4% (after 10cycles of eccentric contraction) in young mdx mice. Muscle force drops from 100% (baseline) to 73.1-68.0% (after 10 cycles of eccentric contraction) in BL10 mice 26,27. The values we observed in EDL muscle of ...
Source: PLOS Currents Muscular Dystrophy - Category: Neurology Authors: Source Type: research