PET studies on dopamine D1 receptors in the human brain with carbon-11-SCH 39166 and carbon-11-NNC 756.
PET studies were carried out on brain dopamine D1 receptors using two new ligands, [11C]SCH 39166 and [11C]NNC 756.


METHODS
Four normal subjects and eight predominantly unilateral patients with early Parkinson's disease were investigated. Each of them underwent both a PET scan with [11C]SCH 39166 and one with [11C]NNC 756. A dose of about 185 MBq (5 mCi) of these ligands was administered intravenously and a dynamic PET scan with an ECAT 931/08 PET camera was carried out. Ratios between the striatal and cerebellar uptake of these compounds were calculated.


RESULTS
Both [11C]SCH 39166 and [11C]NNC 756 accumulated in the striatum. There was also some neocortical binding; 75% of the striatal value in the case of [11C]SCH 39166 and 60% with [11C]NNC 756 which displayed higher (p < 0.01) uptake in the striatum than [11C]SCH 39166. There were no significant side-to-side differences in the controls nor in the parkinsonian patients.


CONCLUSIONS
These results imply that both [11C]SCH 39166 and [11C]NNC 756 can be used in PET studies for the visualization and quantification of dopamine D1 receptors. Since [11C]NNC 756 has a significantly better signal-to-noise ratio in the striatum than [11C]SCH 39166, it seems to offer definite advantages for studies of D1 receptors.
Laihinen
A O
AO
Department of Neurology, University of Turku, Finland.
Rinne
J O
JO
Ruottinen
H M
HM
Någren
K A
KA
Lehikoinen
P K
PK
Oikonen
V J
VJ
Ruotsalainen
U H
UH
Rinne
U K
UK
D000328:Adult; D000368:Aged; D001552:Benzazepines / Q000378:metabolism / Q000493:pharmacokinetics; D001572:Benzofurans / Q000378:metabolism / Q000493:pharmacokinetics; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D002250:Carbon Radioisotopes; D018492:Dopamine Antagonists; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D009928:Organ Specificity; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000378:metabolism; D017447:Receptors, Dopamine D1 / Q000032:analysis* / Q000378:metabolism; D012016:Reference Values; D014055:Tomography, Emission-Computed / Q000379:methods*
D001552:Benzazepines; D001572:Benzofurans; D002250:Carbon Radioisotopes; D018492:Dopamine Antagonists; D017447:Receptors, Dopamine D1; C058081:ecopipam; C075357:odapipam