Growth hormone stimulates the collagen synthesis in human tendon and skeletal muscle without affecting myofibrillar protein synthesis

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  • Simon Doessing, Denmark
  • Katja Maria Heinemeier, Denmark
  • Lars Holm, Denmark
  • Abigail L Mackey, Denmark
  • Peter Schjerling, Denmark
  • Michael Rennie, Denmark
  • Kenneth Smith, Denmark
  • Søren Reitelseder, Denmark
  • Anne-Marie Kappelgaard, Denmark
  • Michael Højby Rasmussen, Denmark
  • Allan Flyvbjerg, Denmark
  • Michael Kjaer, Denmark
  • The Department of Endocrinology and Diabetes
In skeletal muscle and tendon the extracellular matrix confers important tensile properties and is crucially important for tissue regeneration after injury. Musculoskeletal tissue adaptation is influenced by mechanical loading, which modulates the availability of growth factors, including growth hormone (GH) and insulin-like growth factor-I (IGF-I) which may be of key importance. To test the hypothesis that GH promotes matrix collagen synthesis in musculotendinous tissue, we investigated the effects of 14 day administration of 33-50mug/kg/day recombinant human GH (rhGH) in healthy young individuals. rhGH administration caused an increase in serum GH, serum IGF-I, and IGF-I mRNA expression in tendon and muscle. Tendon collagen I mRNA expression and tendon collagen protein synthesis increased by 3.9-fold and 1.3-fold respectively (P<0.01 and P=0.02), and muscle collagen I mRNA expression and muscle collagen protein synthesis increased by 2.3-fold and 5.8-fold respectively (P<0.01 and P=0.06). Myofibrillar protein synthesis was unaffected by elevation of GH and IGF-I. Moderate exercise did not enhance the effects of GH manipulation. Thus, increased GH availability stimulates matrix collagen synthesis in skeletal muscle and tendon, but without any effect upon myofibrillar protein synthesis. The results suggest that GH is more important in strengthening the matrix tissue than for muscle cell hypertrophy in adult human musculotendinous tissue.
Original languageEnglish
JournalJournal of Physiology
Volume15
Issue588(Pt 2)
Pages (from-to)341-51
Number of pages11
ISSN0022-3751
DOIs
Publication statusPublished - 2010

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