We tested the hypothesis that treatment of mdx mouse
muscular dystrophy with the
glucocorticoid deflazacort prevents cardiomyopathic lesions and is accompanied by changes in metabolism and gene expression that reflect the improved tissue integrity. Cardiac muscle pathology, expression of alpha-
cardiac myosin heavy chain,
DNA synthesis,
laminin, and
basic fibroblast growth factor (bFGF) were examined to characterize dystrophy and changes with treatment. The potential of
proton magnetic resonance spectroscopy (H-NMRS) to track cardiac dystrophy and
deflazacort effects was also studied.
Deflazacort (but not equipotent
prednisone) reproducibly decreased lesion prevalence and severity. Treatment also produced cardiomyocyte
hypertrophy and a 5.4-fold increase in alpha-
cardiac myosin content. Expression of bFGF
messenger RNA (
mRNA), notable around lesions, rose 3.3-fold, and
laminin expression rose 2.1-fold after
deflazacort. Studies using H-NMRS showed a cardiac "signature" with less
glycine and
taurine than limb muscle or diaphragm and shifts with progression of dystrophy (distinct from normal aging) in many metabolites. Increased
taurine,
acetate, and
succinate were present after 2 weeks of
deflazacort treatment but were not present after 4 weeks. Although paired kinetic and functional studies of myocardium will be needed to determine the origin of such changes, these results demonstrate the potential application of H-NMRS to monitor clinical
heart disease and treatment. In addition, the metabolic effects of
deflazacort were substantial in preventing the progression of
cardiomyopathy in mdx mice and included increased expression of protectant and stabilizing factors and
hypertrophy of cardiac myocytes.