title: Increased plasma bilirubin in Parkinson patients on L-dopa: evidence against the free radical hypothesis?
abstract: Oxidative damage by free radicals may contribute to the etiology of Parkinson's disease (PD), and increased oxidative stress in the nigral cells of PD patients may occur following L-dopa treatment, prompting suggestions that L-dopa therapy should be delayed as long as possible. Bilirubin is a potent antioxidant in vitro, even when bound to albumin, suggesting a physiological role as an antioxidant. Calculations indicate that bilirubin can pass the blood-brain barrier in sufficient quantity to exert a significant antioxidant effect in the brain. We have found a highly significant (about 20%) increase in plasma bilirubin in 162 PD patients on chronic L-dopa treatment compared to 93 untreated parkinsonians and 224 non-parkinsonian controls. We propose that L-dopa-induced increase in nigral oxidative stress in PD may be effectively counteracted by increased bilirubin levels. The mechanism by which plasma bilirubin is increased in patients receiving L-dopa is at present unknown.
authors.affiliation: Istituto Nazionale Neurologico C. Besta, Milano, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Scigliano
authors.forename: F
authors.initials: F
authors.lastname: Girotti
authors.forename: P
authors.initials: P
authors.lastname: Soliveri
authors.forename: M
authors.initials: M
authors.lastname: Musicco
authors.forename: D
authors.initials: D
authors.lastname: Radice
authors.forename: T
authors.initials: T
authors.lastname: Caraceni
mesh_terms: D000368:Aged; D001663:Bilirubin / Q000097:blood*; D005260:Female; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D007980:Levodopa / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D010300:Parkinson Disease / Q000097:blood* / Q000188:drug therapy
chemical_list: D005609:Free Radicals; D007980:Levodopa; D001663:Bilirubin