Synthesis, tissue distribution in rats and PET studies in baboon brain of no-carrier-added [18F]RU 52461: in vivo evaluation as a brain glucocorticoid receptor radioligand.

11,17 beta-Dihydroxy-6-methyl-17 alpha-(3-[18F]fluoro-prop-1- ynyl)androsta-1,4,6-trien-3-one [( 18F]RU 52461), an 18F-analog of RU 28362, was synthesized by bromide displacement with [18F]fluoride in 12-30% overall radiochemical yield (decay-corrected) within 140 min from end of bombardment (EOB). The specific activity was 900-1500 mCi/mumol (33.3-55.

6-[18F]fluoro-L-dopa uptake and [76Br]bromolisuride binding in the excitotoxically lesioned caudate-putamen of nonhuman primates studied using positron emission tomography.

The functional status of the dopaminergic system following striatal excitotoxic lesions was studied in living baboons by positron emission tomography (PET) using 6-[18F]fluoro-L-dopa as specific tracer for the presynaptic dopaminergic terminals and [76Br]bromolisuride as selective dopamine D2-receptor marker. The glutamate receptor agonist ibotenic acid (IA) was injected into the right caudate-putamen of six baboons to induce a neuropathological and behavioral model of Huntington's disease (HD). In vivo PET studies performed 3 to 6 months after the IA injections showed that subtotal excitotoxic lesions of the CP were accompanied by changes in the kinetic of [76Br]bromolisuride binding indicating a dose-dependent reduction in binding sites in the lesioned striatum of all IA-injected animals.

Kinetic analysis of central [76Br]bromolisuride binding to dopamine D2 receptors studied by PET.

The in vivo kinetic analysis of dopamine D2 receptors was obtained in baboon brain using positron emission tomography (PET) and [76Br]bromolisuride [( 76Br]BLIS) as radioligand. An injection of a trace amount of [76Br]BLIS was followed 3 h later by an injection of a mixture of [76Br]BLIS and BLIS in the same syringe (coinjection experiment). A third injection performed at 6 h was either an excess of unlabeled ligand (displacement experiment) or a second coinjection.

Synthesis, affinity and specificity of 18F-setoperone, a potential ligand for in-vivo imaging of cortical serotonin receptors.

Setoperone, a piperidine derivative known for its potent serotonin and moderate dopamine receptor blocking properties was labelled with the positron emitter 18F using a nucleophilic substitution on the nitro derivative. The general pattern of the in-vivo and in-vitro rat brain distribution of this new radioligand was consistent with the mapping of serotonin (5HT2) and dopamine (D2) receptors. The cortical binding of 18F-setoperone was selectively inhibited by ketanserin and not by sulpiride.