title: Trace amine metabolism in Parkinson's disease: low circulating levels of octopamine in early disease stages.
abstract: Recent evidence suggests that trace amines such as tyramine and octopamine, alternative products of tyrosine metabolism (an aminoacid parent of dopamine and noradrenaline), play a role in the homeostasis of the extrapyramidal system. However, the relevance of these trace amines in the pathogenesis of Parkinson's disease is still largely unknown. Here, we assessed the plasma levels of octopamine and noradrenaline in three sub-groups of PD patients, namely de novo, non-fluctuating and fluctuating patients, versus age-matched control subjects. We show that octopamine is detectable in plasma of all subjects, the mean levels of which are significantly lower in PD patients, including de novo patients, when compared to controls (p<0.001). Unlike this, no changes in plasmatic noradrenaline levels were found in the de novo patients, but only in plasma of fluctuating and non-fluctuating PD patients. These findings raise the possibility that Parkinson's disease is firstly characterized by abnormalities of tyrosine decarboxylase, rather than tyrosine hydroxylase, enzyme activity. Given the role of this enzyme in the production of trace amines, circulating octopamine levels may hold promise as a biomarker of early Parkinson's disease.
authors.affiliation: Villa Margherita Neurology Clinic, via Costacolonna 20, 36100 Arcugnano Vicenza, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: D'Andrea
authors.forename: Gianpietro
authors.initials: G
authors.lastname: Nordera
authors.forename: Gilberto
authors.initials: G
authors.lastname: Pizzolato
authors.forename: Andrea
authors.initials: A
authors.lastname: Bolner
authors.forename: Davide
authors.initials: D
authors.lastname: Colavito
authors.forename: Raffaella
authors.initials: R
authors.lastname: Flaibani
authors.forename: Alberta
authors.initials: A
authors.lastname: Leon
mesh_terms: D000368:Aged; D000588:Amines / Q000378:metabolism; D015415:Biomarkers / Q000097:blood; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood* / Q000378:metabolism; D009655:Octopamine / Q000097:blood* / Q000378:metabolism; D010300:Parkinson Disease / Q000097:blood* / Q000378:metabolism; D013997:Time Factors
chemical_list: D000588:Amines; D015415:Biomarkers; D009655:Octopamine; D009638:Norepinephrine