Melanostatin (MIF-1) is a naturally occurring neuropeptide acting as a positive allosteric modulator (PAM) of dopamine D<sub>2</sub> receptors (D<sub>2</sub>R), underscoring its potential for therapeutic use in central nervous system disorders associated with dopaminergic dysregulation, including depression, drug addiction, restless legs syndrome, tardive dyskinesia, and Parkinson's disease. Here, HERPUD1 is linked to restless legs syndrome.