title: Local administration of growth hormone stimulates tendon collagen synthesis in elderly men.
abstract: Tendon collagen content and circulating growth hormone (GH) are reduced in elderly. In a placebo-controlled, double-blinded study, we examined if local injections of rhGH enhance collagen synthesis in healthy elderly men (61 ± 1 yr). Two injections of rhGH or saline (control) were injected into each of the patient's patellar tendons, respectively. Subsequently, tendon collagen fractional synthesis rate (FSR) and an indirect marker of type I collagen synthesis (PINP) were measured. Within the first 6 h after the last injections, a tendency towards a higher tendon collagen FSR was observed in 10 out of 12 subjects (P = 0.08). Similarly, PINP was higher 3-4 h after the last GH injection (P = 0.05). Serum IGF-I did not change from baseline, whereas peritendinous bioactive IGF-I was higher in the GH leg vs. control (P = 0.05). In conclusion, local injections of rhGH increase tendon collagen synthesis in humans, either directly or indirectly by increasing local bioactive IGF-I.
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital and Medical Research Laboratories, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark.
authors.forename: Poul
authors.initials: P
authors.lastname: Vestergaard
authors.forename: Jens Otto Lunde
authors.initials: JO
authors.lastname: Jørgensen
authors.forename: Jens L
authors.initials: JL
authors.lastname: Olesen
authors.forename: Ermina
authors.initials: E
authors.lastname: Bosnjak
authors.forename: Lars
authors.initials: L
authors.lastname: Holm
authors.forename: Jan
authors.initials: J
authors.lastname: Frystyk
authors.forename: Henning
authors.initials: H
authors.lastname: Langberg
authors.forename: Michael
authors.initials: M
authors.lastname: Kjaer
authors.forename: Mette
authors.initials: M
authors.lastname: Hansen
mesh_terms: D000368:Aged; D003094:Collagen / Q000096:biosynthesis*; D004311:Double-Blind Method; D013006:Growth Hormone / Q000008:administration & dosage; D019382:Human Growth Hormone / Q000008:administration & dosage* / Q000097:blood; D006801:Humans; D007267:Injections; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007700:Kinetics; D008297:Male; D017551:Microdialysis; D008875:Middle Aged; D017847:Patellar Ligament / Q000187:drug effects* / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D011347:Procollagen / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D011347:Procollagen; C047202:procollagen Type I N-terminal peptide; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D003094:Collagen