title: Ethinyl oestradiol administration in women suppresses synthesis of collagen in tendon in response to exercise.
abstract: Women are at greater risk than men of sustaining certain kinds of injury and diseases of collagen-rich tissues. To determine whether a high level of oestradiol has an acute influence on collagen synthesis in tendons at rest and in response to exercise, one-legged kicking exercise was performed for 60 min at 67% of maximum power by healthy, young oral contraceptive (OC) users when circulating synthetic (ethinyl) oestradiol was high (n = 11, HE-OC) and compared to similar women who had never used OCs when circulating endogenous oestrogen was low (n = 12, LE-NOC). Interstitial fluid was collected 24 h post-exercise through microdialysis catheters placed anterior to the patellar tendon in both legs and subsequently analysed for the amino-terminal propeptide of type I collagen (PINP), a marker of tendon collagen synthesis. To determine the long-term effect of OC usage, patellar tendon cross-sectional area (CSA) was measured by magnetic resonance imaging (MRI). A lower exercise-induced increase in tendon collagen synthesis was observed in HE-OC than in LE-NOC (DeltaPINP (mean +/- s.e.m.) 1.5 +/- 5.3 versus 24.2 +/- 9.4 ng ml(-1), P < 0.05). Furthermore, serum and the interstitial peritendinous tissue concentrations of insulin-like growth factor I (IGF-I) and IGF-binding proteins showed a reduced bioavailability in HE-OC compared with results in LE-NOC. No difference in patellar tendon CSA was observed between groups. In conclusion, the selective increase in tendon collagen synthesis in LE-NOC but not HE-OC 24 h post-exercise is consistent with the hypothesis that oestradiol inhibits exercise-induced collagen synthesis in human tendon. The mechanism behind this is either a direct effect of oestradiol, or an indirect effect via a reduction in levels of free IGF-I. However, the data did not indicate any long-term effect on tendon size associated with chronic OC use.
authors.affiliation: Institute of Sports Medicine, Copenhagen, Build. 8, Bispebjerg Hospital, Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark. mh19@bbh.regionh.dk
authors.forename: Mette
authors.initials: M
authors.lastname: Hansen
authors.forename: Satu O
authors.initials: SO
authors.lastname: Koskinen
authors.forename: Susanne G
authors.initials: SG
authors.lastname: Petersen
authors.forename: Simon
authors.initials: S
authors.lastname: Doessing
authors.forename: Jan
authors.initials: J
authors.lastname: Frystyk
authors.forename: Allan
authors.initials: A
authors.lastname: Flyvbjerg
authors.forename: Eva
authors.initials: E
authors.lastname: Westh
authors.forename: S Peter
authors.initials: SP
authors.lastname: Magnusson
authors.forename: Michael
authors.initials: M
authors.lastname: Kjaer
authors.forename: Henning
authors.initials: H
authors.lastname: Langberg
mesh_terms: D000328:Adult; D003094:Collagen / Q000096:biosynthesis*; D015536:Down-Regulation; D004997:Ethinyl Estradiol / Q000494:pharmacology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D005082:Physical Exertion / Q000187:drug effects / Q000502:physiology*; D013710:Tendons / Q000187:drug effects / Q000502:physiology*
chemical_list: D004997:Ethinyl Estradiol; D003094:Collagen