High protein diet has beneficial effects in murine muscular dystrophy.
In normal muscle there is a delicate balance between muscle protein synthesis and protein degradation. It is believed that this balance is disturbed in muscular dystrophy (MD) by decreased muscle protein synthesis and/or increased muscle protein degradation, resulting in net catabolism. In an attempt to reduce or reverse this catabolism, a high protein diet (HPD, 50% protein) was fed to dystrophic mice (129/ReJ dy) for 4 wk. The effects on muscle biochemistry, muscle function and muscle morphology were compared with those in dystrophic mice fed a normal diet (NPD, 20% protein) and in nondystrophic mice (NORM) also fed the 20% protein diet. Compared with NORM mice, NPD mice demonstrated greater rates of muscle protein synthesis (P < 0.05) as measured by the incorporation of labeled phenylalanine into muscle, greater protein degradation (P < 0.01) as measured by urinary 3-methylhistidine excretion, and lower muscle protein concentration (P < 0.01). When dystrophic mice were fed HPD for 4 wk, protein degradation was lower (P < 0.01) and muscle protein concentration greater (P < 0.01) than in NPD mice. These biochemical improvements were accompanied by greater morphological uniformity of muscle fibers, higher volume density of muscle fibers per unit area of muscle (P < 0.01), and lower shape factor (P < 0.01). Functionally, HPD led to improved muscle endurance (P < 0.01) and increased hind-limb utilization (P 0.01). We conclude that in murine dystrophy, HPD decreases net muscle catabolism, principally by decreasing muscle protein degradation, resulting in improvement in muscle morphology, strength and function.
Zdanowicz
M M
MM
Department of Pediatrics, North Shore University Hospital-Cornell University Medical College, Manhasset, NY 11030, USA.
Slonim
A E
AE
Bilaniuk
I
I
O'Connor
M M
MM
Moyse
J
J
Teichberg
S
S
D000818:Animals; D004044:Dietary Proteins / Q000627:therapeutic use*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D008297:Male; D008762:Methylhistidines / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology / Q000502:physiology; D009137:Muscular Dystrophy, Animal / Q000178:diet therapy* / Q000235:genetics / Q000473:pathology; D010649:Phenylalanine / Q000378:metabolism; D013997:Time Factors
D004044:Dietary Proteins; D008762:Methylhistidines; D009124:Muscle Proteins; D010649:Phenylalanine