The activity of satellite cells and myonuclei following 8 weeks of strength training in young men with suppressed testosterone levels. (15th November 2014)

• Record Type: Journal Article
• Authors: Kvorning, T.; Kadi, F.; Schjerling, P.; Andersen, M.; Brixen, K.; Suetta, C.; Madsen, K.
• Is Part Of: Acta physiologica. Volume 213:Number 3(2015:Mar.)
• Page Start: 676
• Page End: 687
• Publication Date: 2014-11-15
• Subjects: Physiology -- Periodicals; Physiology -- Research -- Periodicals; 612
• DOI: 10.1111/apha.12404
• Languages: English
• ISSNs: 1748-1708

Abstract

<abstract abstract-type="main" id="apha12404-abs-0001"> <title>Abstract</title> <sec id="apha12404-sec-0001" sec-type="section"> <title>Aim</title> <p>To investigate how suppression of endogenous testosterone during an 8‐week strength training period influences the activity of satellite cells and myonuclei.</p> </sec> <sec id="apha12404-sec-0002" sec-type="section"> <title>Methods</title> <p>Twenty‐two moderately trained young men participated in this randomized, placebo‐controlled, and double‐blinded intervention study. The participants were randomized to treatment with a GnRH analogue, <italic>goserelin</italic> (<italic>n</italic> = 12), which suppresses testosterone or <italic>placebo</italic> (<italic>n</italic> = 10) for 12 weeks. The strength training period of 8 weeks started after 4 weeks of treatment and included exercises for all major muscles. Biopsies were obtained from the mid‐portion of the vastus lateralis muscle.</p> </sec> <sec id="apha12404-sec-0003" sec-type="section"> <title>Results</title> <p>Testosterone resting level in <italic>goserelin</italic> was 10–20 times lower compared with <italic>placebo, </italic> and the training‐induced increase in the level of testosterone was abolished in <italic>goserelin</italic>. Training increased satellite cells number in type II fibres by 20% in <italic>placebo</italic> and by 52% in <italic>goserelin</italic> (<italic>P</italic> < 0.01), whereas the myonuclear number significantly increased by 12% in type II fibres in <italic>placebo</italic> and remained unchanged in <italic>goserelin</italic> (<italic>P</italic> < 0.05). No changes in satellite cells and myonuclei were seen in type I fibres in either group. Data from the microarray analysis indicated that low testosterone affects the bone morphogenetic proteins signalling, which might regulate proliferation vs. differentiation of satellite cells.</p> </sec> <sec id="apha12404-sec-0004" sec-type="section"> <title>Conclusion</title> <p>Eight weeks of strength training enhances the myonuclear number in type II fibres, and this is largely blocked by the suppression of testosterone. The data indicate that low testosterone levels could reduce the differentiation of satellite cells to myonuclei via the bone morphogenetic proteins signalling pathway, resulting in reduced increases in lean leg mass.</p> </sec> </abstract>