So far, numerous hypotheses on the physiological or pathophysiological role of salsolinol have emerged, mostly with regard to salsolinol as (1) a modulator of catecholaminergic neurotransmission in the nigrostriatal pathway and possibly an etiological factor in Parkinson’s disease (PD), (2) a neuromodulator in the mesolimbic pathway related to reinforcing effects of alcohol consumption, and (3) a prolactin-releasing factor in the tuberoinfundibular pathway. This evidence concerns the gene PRL and Parkinson disease.