Occupancy of Dopamine D3 and D2 Receptors by Buspirone: A [11C]-(+)-PHNO PET Study in Humans.
Neuropsychopharmacology
; 41(2): 529-37, 2016 Jan.
Article
in En
| MEDLINE
| ID: mdl-26089182
There is considerable interest in blocking the dopamine D3 receptor (DRD3) versus the D2 receptor (DRD2) to treat drug addiction. However, there are currently no selective DRD3 antagonists available in the clinic. The anxiolytic drug buspirone has been proposed as a potential strategy as findings suggest that this drug has high in vitro affinity for DRD3, binds to DRD3 in brain of living non-human primate, and also disrupts psychostimulant self-administration in preclinical models. No study has explored the occupancy of DRD3 by buspirone in humans. Here, we used positron emission tomography (PET) and the D3-preferring probe, [(11)C]-(+)-PHNO, to test the hypothesis that buspirone will occupy (decreases [(11)C]-(+)-PHNO binding) the DRD3 more readily than the DRD2. Eight healthy participants underwent [(11)C]-(+)-PHNO scans after single oral dose administration of placebo and 30, 60, and 120 mg of buspirone in a single-blind within-subjects design. [(11)C]-(+)-PHNO binding in DRD2- and DRD3-rich areas was decreased by the highest (60-120 mg), but not the lowest (30 mg), doses of buspirone. The maximal occupancy obtained was ~25% in both areas. Plasma levels of prolactin (a DRD2 marker) correlated with percentage occupancy after orally administered buspirone. Self-reported dizziness and drowsiness increased after buspirone but that did not correlate with receptor occupancy in any region. Overall, the modest occupancy of DRD2 and DRD3 even at high acute doses of buspirone, yielding high levels of metabolites, suggests that buspirone may not be a good drug to preferentially block DRD3 in humans.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Brain
/
Buspirone
/
Dopamine Agents
/
Receptors, Dopamine D2
/
Receptors, Dopamine D3
Type of study:
Clinical_trials
/
Prognostic_studies
Limits:
Adult
/
Female
/
Humans
/
Male
/
Middle aged
Language:
En
Journal:
Neuropsychopharmacology
Journal subject:
NEUROLOGIA
/
PSICOFARMACOLOGIA
Year:
2016
Document type:
Article
Affiliation country:
Canada
Country of publication:
United kingdom