Presynaptic monoaminergic vesicles in Parkinson's disease and normal aging.
We present development and human application of a method for determining the regional cerebral density of the type 2 vesicular monoamine transporter (VMAT2) using positron emission tomography (PET) and [11C]dihydrotetrabenazine (DTBZ). Previous animal studies indicate striatal VMAT2 density is linearly related to the integrity of substantia nigra dopamine neurons and is not subject to drug- or lesion-compensatory regulation. In the present studies, kinetic compartmental modeling was employed to estimate blood-brain [11C]DTBZ transport (K1) and VMAT2 binding site density (tissue-to-plasma DTBZ distribution volume, DV) from the cerebral and plasma DTBZ time courses after intravenous tracer injection. In controls, we found reductions of putamen DTBZ DVwith advancing age, corresponding to losses of 0.77% per year in specific VMAT2 binding. Parkinson's disease (PD) patients had reduction in specific DTBZ DV in the putamen (-61%) and in the caudate nucleus (-43%). There was no overlap of lowest specific putamen DTBZ DV between individual elderly controls and PD patients. The present results indicate the suitability of [11C]DTBZ PET for objective quantification of nigrostriatal integrity, including evaluation of PD progression and its possible therapeutic modification.
Frey
K A
KA
Department of Internal Medicine (Division of Nuclear Medicine), University of Michigan, Ann Arbor, USA.
Koeppe
R A
RA
Kilbourn
M R
MR
Vander Borght
T M
TM
Albin
R L
RL
Gilman
S
S
Kuhl
D E
DE
D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D015415:Biomarkers; D001812:Blood-Brain Barrier; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000493:pharmacokinetics*; D026901:Membrane Transport Proteins; D008875:Middle Aged; D009479:Neuropeptides; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism*; D051381:Rats; D013747:Tetrabenazine / Q000031:analogs & derivatives* / Q000378:metabolism; D014055:Tomography, Emission-Computed; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins
D015415:Biomarkers; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009479:Neuropeptides; C493452:SLC18A2 protein, human; C493454:Slc18a2 protein, rat; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins; C032811:dihydrotetrabenazine; D013747:Tetrabenazine