Screening methods for identifying compounds that bind to or activate (D.sub.1 or D.sub.5 dopamine receptors individually or in combination) or potentially regulate skeletal muscle mass or function in vivo. Also disclosed are screening methods for identifying compounds that prolong or augment the activation of D.sub.1 or D.sub.5 dopamine receptors or of D.sub.1 or D.sub.5 dopamine receptor signal transduction pathways and increase D.sub.1 or D.sub.5 dopamine receptor expression. Pharmaceutical compositions comprising D.sub.1 or D.sub.5 dopamine receptor agonists, antibodies to D.sub.1 or D.sub.5 dopamine receptors and methods for increasing skeletal muscle mass or function or for the treatment of skeletal muscle atrophy using D.sub.1 or D.sub.5 dopamine receptors as the target for intervention and methods for treatment of muscular dystrophies are described.