Strength and endurance in the therapeutic evaluation of prednisolone-treated MDX mice

The dystrophin-deficient, X-linked dystrophic mouse (mdx) was used to evaluate the efficacy of prednisolone treatment. A test protocol was used to take advantage of the quantifiable weakness and disability as well as molecular genetic defect shared with the X-linked Duchenne muscular dystrophy (DMD). Whole-body weakness and fatigue were determined by non-invasive force-transducer physiographic and variable-speed treadmill techniques, respectively. Other measurements included hind-limb muscle protein, calcium, and histomorphology. Subcutaneously-administered prednisolone elicited significant improvements in whole body strength throughout a two-month test period. Increases in strength were also accompanied by measurable increments in running endurance. In fact, prednisolone treatment appeared to protect mdx mice from the stressful effect of continuous running as determined by strength and muscle fiber diameter. Test results from this study support the limited therapeutic benefit observed previously in DMD patients treated with the glucocorticoid.