ISSN:
1435-1463
Keywords:
Amphetamine
;
[11C]
;
L-DOPA
;
raclopride
;
N-methylspiperone
;
CBF
;
PET
;
monkeys
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Positron emission tomography (PET) was used in a multitracer protocol to evaluate D-amphetamine induced effects on dopamine biosynthesis rate and release in propofol anesthetized Rhesus monkeys.l-[β-11C]DOPA was used as biochemical probe to study the brain dopamine biosynthesis rate whilst dopamine release was followed by the binding displacement of the [11C]-radiolabelled dopamine receptor antagonists, raclopride and N-methylspiperone. Studies were performed with either a constant rate intravenous infusion of D-amphetamine aiming at plasma concentrations of 0.2 to 25 ng/ml or with intravenous bolus doses of 0.1 and 0.4 mg/ kg. Decreased binding of the dopamine receptor antagonists was measured in both modes of D-amphetamine administration but notably [11C]N-methylspiperone was less able to sense D-amphetamine induced release of dopamine. At plasma concentrations aimed above 1 ng/ml a levelling off of the binding of [11C]raclopride at 68 ± 8.1% of the baseline value indicated that displacement was only possible from a fraction of the binding sites. Amphetamine was observed to increase the rate constant forl-[β-11C]DOPA utilization in the brain. This was most likely due to an acutely induced subsensitivity of presynaptic dopamine receptors.l-[β-11C]DOPA and [11C]raclopride were found suitable to indicate changes in dopamine synthesis rate and release respectively using PET and can be used to mirror drug-induced changes of brain dopaminergic function.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01277655
