title: Levodopa-induced plasticity: a double-edged sword in Parkinson's disease?
abstract: The long-term replacement therapy with the dopamine (DA) precursor 3,4-dihydroxy-l-phenylalanine (L-DOPA) is a milestone in the treatment of Parkinson's disease (PD). Although this drug precursor can be metabolized into the active neurotransmitter DA throughout the brain, its therapeutic benefit is due to restoring extracellular DA levels within the dorsal striatum, which lacks endogenous DA as a consequence of the neurodegenerative process induced by the disease. In the early phases of PD, L-DOPA treatment is able to restore both long-term depression (LTD) and long-term potentiation (LTP), two major forms of corticostriatal synaptic plasticity that are altered by dopaminergic denervation. However, unlike physiological DA transmission, this therapeutic approach in the advanced phase of the disease leads to abnormal peaks of DA, non-synaptically released, which are supposed to trigger behavioural sensitization, namely L-DOPA-induced dyskinesia. This condition is characterized by a loss of synaptic depotentiation, an inability to reverse previously induced LTP. In the advanced stages of PD, L-DOPA can also induce non-motor fluctuations with cognitive dysfunction and neuropsychiatric symptoms such as compulsive behaviours and impulse control disorders. Although the mechanisms underlying the role of L-DOPA in both motor and behavioural symptoms are still incompletely understood, recent data from electrophysiological and imaging studies have increased our understanding of the function of the brain areas involved and of the mechanisms implicated in both therapeutic and adverse actions of L-DOPA in PD patients.
authors.affiliation: Clinica Neurologica, Dipartimento di Medicina, Università degli Studi di Perugia, Ospedale Santa Maria della Misericordia, S. Andrea delle Fratte, Via Gambuli, Perugia 06156, Italy Fondazione Santa Lucia, IRCCS, via del Fosso di Fiorano 64, Rome 00143, Italy paolo.calabresi@unipg.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Calabresi
authors.affiliation: Dipartimento di Filosofia, Scienze Sociali, Umane e della Formazione, Università degli Studi di Perugia, Piazza Ermini 1, Perugia 06123, Italy Fondazione Santa Lucia, IRCCS, via del Fosso di Fiorano 64, Rome 00143, Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Ghiglieri
authors.affiliation: Clinica Neurologica, Dipartimento di Medicina, Università degli Studi di Perugia, Ospedale Santa Maria della Misericordia, S. Andrea delle Fratte, Via Gambuli, Perugia 06156, Italy Fondazione Santa Lucia, IRCCS, via del Fosso di Fiorano 64, Rome 00143, Italy.
authors.forename: Petra
authors.initials: P
authors.lastname: Mazzocchetti
authors.affiliation: Clinica Neurologica, Dipartimento di Medicina, Università degli Studi di Perugia, Ospedale Santa Maria della Misericordia, S. Andrea delle Fratte, Via Gambuli, Perugia 06156, Italy.
authors.forename: Ilenia
authors.initials: I
authors.lastname: Corbelli
authors.affiliation: Fondazione Santa Lucia, IRCCS, via del Fosso di Fiorano 64, Rome 00143, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Picconi
mesh_terms: D002540:Cerebral Cortex / Q000503:physiopathology*; D003342:Corpus Striatum / Q000503:physiopathology*; D004298:Dopamine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D007980:Levodopa / Q000009:adverse effects* / Q000494:pharmacology*; D009473:Neuronal Plasticity / Q000187:drug effects* / Q000502:physiology; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology*
chemical_list: D007980:Levodopa; D004298:Dopamine
keywords: Levodopa treatment; Parkinson's disease; animal models; synaptic plasticity