Variability in D2-dopamine receptor density and affinity: a PET study with [11C]raclopride in man.
The variability of D2-dopamine receptor binding parameters in man was determined using Positron Emission Tomography (PET) and [11C]raclopride. A saturation analysis based on five PET-experiments was performed in each of ten men and ten women. The mean density of D2-dopamine receptors (Bmax) was 28 +/- 6.9 pmol/ml (mean +/- S.D.) and the apparent affinity (Kdapp) 9.1 +/- 1.9 pmol/ml. The Hill coefficient was in all subjects close to unity (nH: 0.999 +/- 0.020), thereby indicating binding to a homogeneous class of receptors. No significant differences between males and females were found in Bmax or Kdapp. The interindividual difference in Bmax was statistically significant (alpha = 0.01). The difference in Kdapp was not significant. Upregulation of the receptor density (Bmax) has been widely discussed as a mechanism for increased dopaminergic neurotransmission in schizophrenia. This study indicates that receptor density varies considerably in a group of healthy subjects.
Farde
L
L
Karolinska Institutet, Department of Clinical Neuroscience, Stockholm, Sweden.
Hall
H
H
Pauli
S
S
Halldin
C
C
D000328:Adult; D000375:Aging / Q000378:metabolism; D001921:Brain / Q000033:anatomy & histology; D001923:Brain Chemistry / Q000187:drug effects; D018492:Dopamine Antagonists / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008745:Methylation; D020891:Raclopride; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000378:metabolism*; D012457:Salicylamides / Q000493:pharmacokinetics; D012727:Sex Characteristics; D014055:Tomography, Emission-Computed
D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; D012457:Salicylamides; D020891:Raclopride