1 Department of Clinical Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet2 Department of Endocrinology and Internal Medicine, Aarhus University Hospital and Medical Research Laboratories, Institute of Clinical Medicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark;3 Department of Rheumatology, Aalborg Hospital–Aarhus University Hospital, Aalborg, Denmark4 Section of Systems Biology Research, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, Københavns Universitet5 Institut for Idrætsmedicin, Bispebjerg Hospital6 Institute of Sports Medicine, Department Orthopedic Surgery M81, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark7 Section of Systems Biology Research, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, Københavns Universitet8 Department of Clinical Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet
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.
Journal of Applied Physiology, 2012, Vol 113, Issue 9, p. 1432-1438