"The interaction between L-DOPA and 5-HT transmission is especially relevant in those Parkinson's disease (PD) patients that suffer dyskinesia, comorbid anxiety or depression, since the efficacy of antidepressants or 5-HT compounds may be affected."
Frontiers | Impairment of Serotonergic Transmission by the Antiparkinsonian Drug L-DOPA: Mechanisms and Clinical Implications | Frontiers in Cellular Neuroscience