title: Dietary HMB and β-alanine co-supplementation does not improve in situ muscle function in sedentary, aged male rats.
abstract: This study evaluated the effects of dietary β-hydroxy-β-methylbutyrate (HMB) combined with β-alanine (β-Ala) in sedentary, aged male rats. It has been suggested that dietary HMB or β-Ala supplementation may mitigate age-related declines in muscle strength and fatigue resistance. A total of 20 aged Sprague-Dawley rats were studied. At age 20 months, 10 rats were administered a control, purified diet and 10 rats were administered a purified diet supplemented with both HMB and β-Ala (HMB+β-Ala) for 8 weeks (approximately equivalent to 3 and 2.4 g per day human dose). We measured medial gastrocnemius (MG) size, force, fatigability, and myosin composition. We also evaluated an array of protein markers related to muscle mitochondria, protein synthesis and breakdown, and autophagy. HMB+β-Ala had no significant effects on body weight, MG mass, force or fatigability, myosin composition, or muscle quality. Compared with control rats, those fed HMB+β-Ala exhibited a reduced (41%, P = 0.039) expression of muscle RING-finger protein 1 (MURF1), a common marker of protein degradation. Muscle from rats fed HMB+β-Ala also exhibited a 45% reduction (P = 0.023) in p70s6K phosphorylation following fatiguing stimulation. These data suggest that HMB+β-Ala at the dose studied may reduce muscle protein breakdown by reducing MURF1 expression, but has minimal effects on muscle function in this model of uncomplicated aging. They do not, however, rule out potential benefits of HMB+β-Ala co-supplementation at other doses or durations of supplementation in combination with exercise or in situations where extreme muscle protein breakdown and loss of mass occur (e.g., bedrest, cachexia, failure-to-thrive).
authors.affiliation: a Laboratory for Integrative Muscle Biology, Division of Physical Therapy, School of Rehabilitation and Communication Sciences, Ohio University, Athens, OH 45701, USA.|b Ohio Musculoskeletal and Neurological Institute (OMNI), Heritage College of Osteopathic Medicine, Athens, OH 45701, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Russ
authors.affiliation: a Laboratory for Integrative Muscle Biology, Division of Physical Therapy, School of Rehabilitation and Communication Sciences, Ohio University, Athens, OH 45701, USA.|c Division of Nutrition, School of Applied Health Sciences and Wellness, Ohio University, Athens, OH 45701, USA.
authors.forename: Cara
authors.initials: C
authors.lastname: Acksel
authors.affiliation: a Laboratory for Integrative Muscle Biology, Division of Physical Therapy, School of Rehabilitation and Communication Sciences, Ohio University, Athens, OH 45701, USA.
authors.forename: Iva M
authors.initials: IM
authors.lastname: Boyd
authors.affiliation: a Laboratory for Integrative Muscle Biology, Division of Physical Therapy, School of Rehabilitation and Communication Sciences, Ohio University, Athens, OH 45701, USA.
authors.forename: John
authors.initials: J
authors.lastname: Maynard
authors.affiliation: a Laboratory for Integrative Muscle Biology, Division of Physical Therapy, School of Rehabilitation and Communication Sciences, Ohio University, Athens, OH 45701, USA.
authors.forename: Katherine W
authors.initials: KW
authors.lastname: McCorkle
authors.affiliation: d Abbott Nutrition R&D, 3300 Stelzer Road, Columbus, OH 43219, USA.
authors.forename: Neile K
authors.initials: NK
authors.lastname: Edens
authors.affiliation: d Abbott Nutrition R&D, 3300 Stelzer Road, Columbus, OH 43219, USA.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Garvey
mesh_terms: D000367:Age Factors; D000375:Aging; D000818:Animals; D001343:Autophagy; D015415:Biomarkers / Q000378:metabolism; D019587:Dietary Supplements; D004195:Disease Models, Animal; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D018763:Muscle Fatigue; D009124:Muscle Proteins / Q000378:metabolism; D053580:Muscle Strength / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D010766:Phosphorylation; D059748:Proteolysis; D017207:Rats, Sprague-Dawley; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D055948:Sarcopenia / Q000209:etiology / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D057185:Sedentary Behavior; D024744:Skeletal Muscle Myosins / Q000378:metabolism; D013997:Time Factors; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D014631:Valerates / Q000494:pharmacology*; D015091:beta-Alanine / Q000494:pharmacology*
chemical_list: D015415:Biomarkers; D009124:Muscle Proteins; D000070584:Tripartite Motif Proteins; D014631:Valerates; D015091:beta-Alanine; C004961:beta-hydroxyisovaleric acid; C499086:Trim63 protein, rat; D044767:Ubiquitin-Protein Ligases; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D024744:Skeletal Muscle Myosins
keywords: MURF1; contraction; fatigue; muscle squelettique; nutrition; sarcopenia; sarcopénie; skeletal muscle