Objective
To investigate the effect of steroid administration on the apoptosis and heat shock protein 70 (HSP70) expression after exercise in the animal model of Duchenne muscular dystrophy. Method: We measured Bcl-2, BAX and HSP70 expression by western blotting. 20 control and 20 mdx mice were divided into free-living (n=10) and exercise (n=10) groups. Free-living and exercise groups were further divided into steroid-treated and sham-treated groups to evaluate the effect of steroid administration. Results: Apoptosis was most prominent in the sham-treated exercise group, while apoptosis was significantly reduced in the steroid-treated exercise group. HSP70 expression was maximized in sham-treated exercise group, whereas steroid administration inhibited HSP70 expression after exercise in muscular dystrophy animal model. Exercise loading was found to cause severe apoptosis but steroid administration alleviated apoptotic damage in mdx mice. sConclusion: HSP70 expression was suppressed in the steroid-treated exercise group, which suggests steroid might have major preventive effect in exercise-induced apoptosis of muscular dystrophy animal model. (J Korean Acad Rehab Med 2009; 33: 1-4)

Objective
To investigate the effect of exercise and steroid to the muscle of animal model of Duchenne muscular dystrophy.

Method: We used 15 mdx and 15 control mice. To grade exercise loading, control and mdx mice were divided into free-living, exercise and immobilization groups. Free-living and exercise groups were further divided into steroid-treated and sham-treated groups to evaluate the effect of steroid administration. We measured the apoptotic changes using in situ DNA nick-end labling (TUNEL), DNA fragmentation assay and western blots for Bcl-2 and BAX.

Results: With TUNEL method, the largest number of myonuclei became positive in sham-treated exercise group while apoptosis was significantly reduced in steroid-treated exercise group in mdx mice. Steroid-treated free-living group showed higher rate of apoptotic change than sham-treated free-living group. With western blots for Bcl-2 and BAX, the value of BAX/Bcl-2 ratio was highest in sham-treated exercise group and among free living mdx mice, it was higher in steroid-treated group than sham-treated one.

Conclusion: Apoptosis can be minimized in free living condition while exercise loading or immobilization can cause apoptotic change in muscular dystrophy animal model. Steroid administration induces apoptosis in free living muscle and it alleviates apoptotic damage caused by exercise loading in mdx mice. (J Korean Acad Rehab Med 2003; 27: 232-239)