Compositions and methods of treating a central nervous system (CNS) disorder or mood disorder in a subject in need of such treatment are described. A therapeutically effective amount of a composition comprising a melanocortin 5 receptor (MC5R) peptide ligand in a pharmaceutically acceptable carrier is administered to the subject. The MCSR peptide ligand is a selective MCSR antagonist, in which administration thereof to the subject can treat the CNS disorder or mood disorder with clinical improvement observed in a relatively short time.