The Effect of L-Carnitine Supplementation on the Dystrophic Muscle and Exercise Tolerance of Muscular Dystrophy (mdx) Mice

ABSTRACT

BACKGROUND: Duchenne muscular dystrophy is an X-linked recessive disorder leading to death in the late teens or early twenties. There is no effective pharmacological therapy for now. L-carnitine (LCAR), a naturally occurring compound facilitating the transport of fatty acid into mitochondria for -oxidation, has been getting an attention for its antiapoptotic and osmoprotective effect. The aim of this study is to evaluate if LCAR administration reduces dystrophic progression and enhances exercise tolerance in dystrophin deficient (mdx) mice. METHODS: Mdx mice (n=5) and wild type mice (n=5), aged 3 weeks were treated with oral LCAR (75mg/kg/day) for 6 weeks. Five each mdx and wild type mice were recruited for their counter-control. The animals underwent a 30-minute run on a horizontal treadmill for evaluating their exercise endurance. After 6-week training, baseline and post exercise serum CK of each group were analyzed. We examined sarcolemma integrity and muscle histology after exercise. Immunofluorescent stain and Western blot analysis for dystrophin-dystroglycan complex were also performed. RESULTS: LCAR-treated mdx mice showed higher exercise tolerance and lower serum CK value compared with those of control mice. The area of Evans blue dye uptake in LCAR-treated mdx mice was much smaller than that of control mdx mice. There was no remarkable difference in dystrophin-dystroglycan complex expression between treated and control mdx mice. CONCLUSIONS: LCAR seems to enhance exercise tolerance and decrease the breakdown of sarcolemma during strenuous exercise. Our study suggests the possibility of adjunctive therapeutic use of L-carnitine to the patients with Duchenne muscular dystrophy.