Morphological and functional changes in skeletal muscle of the Huntington's disease mouse model R6/2 suggest selective changes in fast-twitch fibres

Skeletal muscle atrophy in Huntington's disease is usually thought to be secondary to the onset of neurological symptoms. We have studied morphological and physiological changes in skeletal muscle of the R6/2 mouse model 12–16 weeks of age. Morphological changes include an increase in centrally located nuclei and activated nuclei. In addition fibre size varies widely in the R6/2 skeletal muscle and some muscle fibres show an increase in subsarcolemmal mitochondria. Electron microscopy pictures of 12 weeks old muscle detected enlarged mitochondria and widening of the z-disc in a subset of muscle fibres with neigh…