title: Suppression of testosterone does not blunt mRNA expression of myoD, myogenin, IGF, myostatin or androgen receptor post strength training in humans.
abstract: We hypothesized that suppression of endogenous testosterone blunts mRNA expression post strength training (ST). Twenty-two young men were randomized for treatment with the GnRH analogue goserelin (3.6 mg every 4 weeks) or placebo for a period of 12 weeks. The ST period of 8 weeks started at week 4. Strength test, blood sampling, muscle biopsies, and whole-body dual-energy X-ray absorptiometry (DXA) scan were performed at weeks 4 and 12. Muscle biopsies were taken during the final ST session (pre, post 4 h, and post 24 h). Resting serum testosterone decreased significantly (P < 0.01) in the goserelin group from 22.6 +/- 1.6 (mean +/- s.e.m.) to 2.0 +/- 0.1 nmol l(-1) (week 4), whereas it remained unchanged in the placebo group. An acute increase of serum testosterone was observed during the final ST session in the placebo group (P < 0.05), whereas a decreased response was observed in the goserelin group (P < 0.05). mRNA expression of IGF-IE(bc) and myogenin increased, while expression of myostatin decreased (P < 0.01); however, no differences were observed between the groups. Muscle strength and muscle mass showed a tendency to increase more in the placebo group than in the goserelin group (P = 0.05). In conclusion, despite blocked acute responses of testosterone and 10- to 20-fold lower resting levels in the goserelin group, ST resulted in a similar mRNA expression of myoD, myogenin, IGF-IE(abc), myostatin and androgen receptor as observed in the placebo group. Therefore, in the present study, the molecular events were the same, despite divergent muscle hypertrophy and strength gains.
authors.affiliation: Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark. tkvorning@health.sdu.dk
authors.forename: Thue
authors.initials: T
authors.lastname: Kvorning
authors.forename: Marianne
authors.initials: M
authors.lastname: Andersen
authors.forename: Kim
authors.initials: K
authors.lastname: Brixen
authors.forename: Peter
authors.initials: P
authors.lastname: Schjerling
authors.forename: Charlotte
authors.initials: C
authors.lastname: Suetta
authors.forename: Klavs
authors.initials: K
authors.lastname: Madsen
mesh_terms: D000328:Adult; D015152:Blotting, Northern; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D017273:Goserelin / Q000494:pharmacology; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000235:genetics; D007537:Isometric Contraction / Q000187:drug effects; D007866:Leg / Q000502:physiology; D008297:Male; D009124:Muscle Proteins / Q000235:genetics*; D053580:Muscle Strength / Q000187:drug effects; D017570:MyoD Protein / Q000235:genetics; D018008:Myogenin / Q000235:genetics; D055435:Myostatin; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011944:Receptors, Androgen / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D013739:Testosterone / Q000097:blood*; D016212:Transforming Growth Factor beta / Q000235:genetics
chemical_list: C525911:MSTN protein, human; D009124:Muscle Proteins; D017570:MyoD Protein; D018008:Myogenin; D055435:Myostatin; D012333:RNA, Messenger; D011944:Receptors, Androgen; D012738:Sex Hormone-Binding Globulin; D016212:Transforming Growth Factor beta; D017273:Goserelin; D019382:Human Growth Hormone; D013739:Testosterone; D007334:Insulin-Like Growth Factor I; D006854:Hydrocortisone