title: Myostatin expression during human muscle hypertrophy and subsequent atrophy: increased myostatin with detraining.
abstract: Myostatin is a potent negative regulator of skeletal muscle mass, but its role in human skeletal muscle hypertrophy and atrophy is sparsely described. Muscle biopsies were obtained from young male subjects before and after 30 and 90 days of resistance training as well as after 3, 10, 30, 60 and 90 days of subsequent detraining. Myostatin mRNA increased significantly with detraining. We observed a 28 kDa myostatin immunoreactive protein, which, however, was also present in myostatin knock out mice skeletal muscle. As a novel finding we consistently detected a 10 kDa band, which may represent a mature myostatin monomer under reducing conditions or a novel, unknown myostatin form. Further, we observed a significant increase in this 10 kDa band after 3 days of detraining preceding the rapid type II fiber atrophy, in which almost half of the acquired fiber area was lost after only 10 days of detraining. Accordingly, an increase in the level of the 10 kDa protein is associated with rapid type II fiber atrophy, suggesting myostatin-mediated specific type II fiber atrophy, which in combination with our mRNA data support a role for myostatin in the negative regulation of adult human skeletal muscle mass.
authors.affiliation: Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. jespersen.jakob@gmail.com
authors.forename: J G
authors.initials: JG
authors.lastname: Jespersen
authors.forename: A
authors.initials: A
authors.lastname: Nedergaard
authors.forename: L L
authors.initials: LL
authors.lastname: Andersen
authors.forename: P
authors.initials: P
authors.lastname: Schjerling
authors.forename: J L
authors.initials: JL
authors.lastname: Andersen
mesh_terms: D000328:Adult; D000818:Animals; D006801:Humans; D006984:Hypertrophy / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology* / Q000502:physiology; D009133:Muscular Atrophy / Q000378:metabolism*; D055435:Myostatin / Q000378:metabolism* / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism*; D055070:Resistance Training; D055815:Young Adult
chemical_list: D055435:Myostatin; D012333:RNA, Messenger