title: β-Hydroxy-β-methylbutyrate improves bone properties and attenuates the depression of protein synthesis during a simulated sustained operation.
abstract: OBJECTIVE
  Soldiers lose muscle and bone density during sustained operations. We investigated the impact of β-hydroxy-β-methylbutyrate (HMB) on bone properties, muscle mass, and markers of skeletal muscle regeneration under simulated military sustained operations.
  
  
  METHODS
  Male mice were divided into four groups (10/group): (1) ALT = ad libitum + trained (1h/d for 3 d/wk); (2) ALTH = ALT + HMB (0.5 g/kg BW/d); (3) C = caloric restricted (-30%) + trained (6h/d, 6d/wk); and (4) CH = C + HMB. Assessments included bone mineral density/content by dual-energy X-ray absorptiometry, muscle wet weight (quadriceps) and expression of selected genes regulating muscle mass and protein turnover. Analysis of variances were used with significance set at p < 0.05.
  
  
  RESULTS
  Bone mineral content increased in the ALT group (+16%) and decreased in the C group (-32%). Quadriceps muscle mass was lower in C (-27%) and CH (-19%) compared to ALT and ALTH. Myogenin mRNA expression was higher in C than ALT, ALTH and CH. Protein kinase B (Akt) mRNA expression was higher in both C and CH than ALT and ALTH. Mammalian target of rapamycin expression was higher in CH than ALT and ALTH. Muscle RING-finger protein-1 expression was higher in both C and CH than ALT and ALTH.
  
  
  CONCLUSIONS
  HMB intake improved bone properties and attenuated the depression of protein synthesis during a simulated sustained military operation.
authors.affiliation: Military Performance Division, United States Army Research Institute of Environmental Medicine, Kansas Street, Building 42, Natick, MA 01760.
authors.forename: Paul C
authors.initials: PC
authors.lastname: Henning
authors.affiliation: Department of Nutrition, Food, and Exercise Sciences, College of Human Sciences, The Florida State University, 432 Sandels Building, Tallahassee, FL 32306.
authors.forename: Bong-Sup
authors.initials: BS
authors.lastname: Park
authors.affiliation: Department of Nutrition, Food, and Exercise Sciences, College of Human Sciences, The Florida State University, 432 Sandels Building, Tallahassee, FL 32306.
authors.forename: Jeong-Su
authors.initials: JS
authors.lastname: Kim
mesh_terms: D000818:Animals; D015519:Bone Density / Q000187:drug effects*; D015870:Gene Expression / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009124:Muscle Proteins / Q000235:genetics; D017570:MyoD Protein / Q000235:genetics; D018008:Myogenin / Q000235:genetics; D010805:Physical Conditioning, Animal; D063150:Polycomb Repressive Complex 1 / Q000235:genetics; D014176:Protein Biosynthesis / Q000187:drug effects*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics; D052097:Quadriceps Muscle / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics; D058570:TOR Serine-Threonine Kinases / Q000235:genetics; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases / Q000235:genetics; D014631:Valerates / Q000494:pharmacology*
chemical_list: D009124:Muscle Proteins; D017570:MyoD Protein; D018008:Myogenin; D012333:RNA, Messenger; D000070584:Tripartite Motif Proteins; D014631:Valerates; C004961:beta-hydroxyisovaleric acid; C486691:Fbxo32 protein, mouse; D063150:Polycomb Repressive Complex 1; C489840:Ring1 protein, mouse; D044843:SKP Cullin F-Box Protein Ligases; C499084:Trim63 protein, mouse; D044767:Ubiquitin-Protein Ligases; C546843:mTOR protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases