Lack of effect of anabolic steroids on specific mRNAs of skeletal muscle undergoing compensatory hypertrophy.

Compensatory hypertrophy of the fast-twitch plantaris muscle (HP) was induced in male rats to determine whether the resulting translational activity of isolated polyribosomes could be modified in this process and by the androgen status. HP induced a significant increase in free androgen binding sites and a typical protein synthesis pattern characterized by a slow myosin light chain isozyme (LC-1S), an increase in fast isozymes (LC-1F,2F) and of beta-tropomyosin/alpha-tropomyosin ratio. The variations in receptor occupancy following castration and treatments with four anabolic steroids (AS) did not result in modification of the template activity of major HP mRNAs. These data suggest that the slight increase of steroid receptors found in HP remains insufficient to trigger an androgenic response in skeletal muscle.