title: Elevated [(18)F]FDOPA utilization in the periaqueductal gray and medial nucleus accumbens of patients with early Parkinson's disease.
abstract: PET studies with the DOPA decarboxylase substrate 6-[(18)F]fluoro-l-DOPA (FDOPA) reveal the storage of [(18)F]-fluorodopamine within synaptic vesicles, mainly of dopamine fibres. As such, FDOPA PET is a sensitive indicator of the integrity of the nigrostriatal dopamine innervation. Nonetheless, there have been several reports of focal elevations of FDOPA utilization in brain of patients with Parkinson's disease (PD), all based on reference tissue methods. To investigate this phenomenon further, we used voxel-wise steady-state kinetic analysis to search for regions of elevated FDOPA utilization (K; ml g(-1) min(-1)) and steady-state trapping (V(d); ml g(-1)) in a group of well-characterized patients with early, asymmetric PD, who were contrasted with an age-matched control group. Subtraction of the population mean parametric maps revealed foci of increased FDOPA utilization K (+25%) in the bilateral medial nucleus accumbens, whereas the expected declines in the trapping of FDOPA were seen in the caudate and putamen. This observation suggests hyperfunction of catecholamine fibres innervating specifically the limbic striatum, which could guide the design of future prospective FDOPA-PET studies of the impulse control disorders occurring in some PD patients under treatment with dopamine agonists. A focus of increased FDOPA influx and also V(d) was detected in the periaqueductal grey, consistent with some earlier reports based on reference tissue analysis. Increased FDOPA trapping in the periaqueductal grey of PD patients seems consistent with recent reports of increased activity of serotonin neurons in a rat model of parkinsonism.
authors: Centre for Functionally Integrative Neuroscience, Aarhus University, Denmark. yoshi.kumakura@gmail.com
authors: Yoshitaka
authors: Y
authors: Kumakura
authors: Erik H
authors: EH
authors: Danielsen
authors: Albert
authors: A
authors: Gjedde
authors: Ingo
authors: I
authors: Vernaleken
authors: Hans-Georg
authors: HG
authors: Buchholz
authors: Andreas
authors: A
authors: Heinz
authors: Gerhard
authors: G
authors: Gründer
authors: Peter
authors: P
authors: Bartenstein
authors: Paul
authors: P
authors: Cumming
mesh_terms: D000328:Adult; D000368:Aged; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009714:Nucleus Accumbens / Q000000981:diagnostic imaging* / Q000378:metabolism*; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000378:metabolism*; D010487:Periaqueductal Gray / Q000000981:diagnostic imaging* / Q000378:metabolism*; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics
chemical_list: D019275:Radiopharmaceuticals; C043437:fluorodopa F 18; D004295:Dihydroxyphenylalanine