Myotrophic effects of an anabolic steroid in rabbit limb muscles.

There has been no reliable evidence that the actions of anabolic steroids extend to limb muscles. In this study, female rabbits were treated with anabolic steroid (nandrolone decanoate) or arachis oil placebo for 4 weeks or 12 weeks. After 12 weeks, tibialis anterior muscles of treated animals showed highly significant increases in wet weight (38%), twitch tension (66%), maximum isometric tetanic tension (48%), maximum cross-sectional area (27%), and specific tension (17%). Fiber type composition showed a significant trend toward a less oxidative metabolic character. The experiments provided clear physiological and morphological evidence of a steroid-induced hypertrophy that was not attributable to fluid retention or changes in body weight. Of the muscles examined, the myotrophic effect was confined to the tibialis anterior muscle; extensor digitorum longus, plantaris, and soleus muscles showed no significant response. The work establishes an experimental model for the responses of limb muscles to anabolic compounds.