Striatal presynaptic monoaminergic vesicles are not increased in Tourette's syndrome.
BACKGROUND
Abnormal function of striatal dopaminergic synapses is suggested to underlie Tourette's syndrome (TS).


OBJECTIVE
To determine dorsal striatal dopaminergic innervation in TS. Prior in vitro and in vivo studies of dopamine reuptake transporter binding sites suggest increased striatal dopaminergic innervation in TS.


METHODS
We used in vivo measures of striatal vesicular monoamine transporter type-2 (VMAT2) binding to quantify striatal dopaminergic innervation in TS. Eight TS patients (mean age 30+/-9 years) and 22 age-comparable normal controls (age 34+/-8 years) underwent PET imaging with the VMAT2 ligand (+)-alpha-[11C]dihydrotetrabenazine (DTBZ). Compartmental modeling was used to quantify blood-to-brain ligand transport and VMAT2 binding site density from the tissue-to-plasma distribution volume (DV) during continuous (+)-alpha-[11C]DTBZ infusion. DTBZ DV in dorsal striatal regions was expressed relative to the occipital cortex to estimate relative specific VMAT2 binding (binding potential).


RESULTS
We found no significant differences in VMAT2 binding potential between patients and controls in the caudate nucleus, anterior putamen, or posterior putamen. There were no significant differences in striatal VMAT2 binding between patients with (n = 5) or without (n = 3) features of obsessive-compulsive disorder.


CONCLUSIONS
There is no evidence for increased binding to the VMAT2 in TS striatum and that dorsal striatal dopaminergic innervation density is normal in TS. The previously reported changes in dopamine transporter binding sites may reflect medication effect and/or altered synaptic activity or regulation of dopamine transporter expression in nigrostriatal neurons.
Meyer
P
P
Department of Internal Medicine, The University of Michigan Medical School, Ann Arbor, USA.
Bohnen
N I
NI
Minoshima
S
S
Koeppe
R A
RA
Wernette
K
K
Kilbourn
M R
MR
Kuhl
D E
DE
Frey
K A
KA
Albin
R L
RL
D000328:Adult; D003342:Corpus Striatum / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008875:Middle Aged; D009479:Neuropeptides; D018377:Neurotransmitter Agents / Q000378:metabolism*; D014055:Tomography, Emission-Computed / Q000379:methods; D005879:Tourette Syndrome / Q000000981:diagnostic imaging*; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins
D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009479:Neuropeptides; D018377:Neurotransmitter Agents; C493452:SLC18A2 protein, human; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins