Leucine supplementation accelerates connective tissue repair of injured tibialis anterior muscle

• Published in: Nutrients Vol. 6; no. 10; pp. 3981 - 4001
• Main Authors: Pereira, Marcelo G, Silva, Meiricris T, Carlassara, Eduardo O C, Gonçalves, Dawit A, Abrahamsohn, Paulo A, Kettelhut, Isis C, Moriscot, Anselmo S, Aoki, Marcelo S, Miyabara, Elen H
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 29.09.2014; MDPI
• Subjects: Angiogenesis; Animals; Collagen - drug effects; Connective tissue; Connective Tissue - drug effects; Connective Tissue - metabolism; Connective Tissue - pathology; Dietary Supplements; Electronic mail systems; Growth factors; Kinases; Leucine - administration & dosage; Leucine - pharmacology; leucine supplementation; Male; Morphology; Muscle, Skeletal - injuries; Muscle, Skeletal - metabolism; Musculoskeletal system; Myofibrils - drug effects; Myosin Heavy Chains - drug effects; Protein synthesis; Protein-Serine-Threonine Kinases - metabolism; Proteins; Rats; Rats, Wistar; Receptor, Transforming Growth Factor-beta Type I; Receptors, Transforming Growth Factor beta - metabolism; Regeneration - drug effects; repair; skeletal muscle injury; Smad2 Protein - metabolism; Smad2/3; Smad3 Protein - metabolism; Spasm - diet therapy; Tibia; transforming growth factor-β receptor type I; Brazil
• DOI: 10.3390/nu6103981
• ISSN: 2072-6643

This study investigated the effect of leucine supplementation on the skeletal muscle regenerative process, focusing on the remodeling of connective tissue of the fast twitch muscle tibialis anterior (TA). Young male Wistar rats were supplemented with leucine (1.35 g/kg per day); then, TA muscles from the left hind limb were cryolesioned and examined after 10 days. Although leucine supplementation induced increased protein synthesis, it was not sufficient to promote an increase in the cross-sectional area (CSA) of regenerating myofibers (p > 0.05) from TA muscles. However, leucine supplementation reduced the amount of collagen and the activation of phosphorylated transforming growth factor-β receptor type I (TβR-I) and Smad2/3 in regenerating muscles (p < 0.05). Leucine also reduced neonatal myosin heavy chain (MyHC-n) (p < 0.05), increased adult MyHC-II expression (p < 0.05) and prevented the decrease in maximum tetanic strength in regenerating TA muscles (p < 0.05). Our results suggest that leucine supplementation accelerates connective tissue repair and consequent function of regenerating TA through the attenuation of TβR-I and Smad2/3 activation. Therefore, future studies are warranted to investigate leucine supplementation as a nutritional strategy to prevent or attenuate muscle fibrosis in patients with several muscle diseases.