Effects of Mesterolone on satellite cell distribution and myonuclear number in maturing skeletal muscle fibers

Mesterolone is a synthetic oral anabolic steroid usually used to treat hypogonadism. Mesterolone abuse has been frequently reported in human and equine sports, in which it is used to increase muscle mass and strength. However, little is known about the effects of mesterolone on satellite cells (SCs), which permit muscle growth by forming new myonuclei. This study tests the hypothesis that mesterolone induced muscle hypertrophy is associated with an increase in the number of SCs. Using immunocytochemical techniques and morphometric analyses, fiber size and numbers of SCs and myonuclei in the pectoralis muscle of maturing chickens were quantified. Mesterolone significantly increased fiber size by approximately 36% (P<0.01). In addition, numbers of SCs and myonuclei were significantly increased by mesterolone administration (P<0.01). These results demonstrate that mesterolone‐induced skeletal muscle hypertrophy is associated with increased numbers of SCs during maturation. Funds for this study were provided by a grant from the Deanship of Research at Jordan University of Science & Technology (25/2010). Grant Funding Source : Deanship of Research, JUST