Central serotonergic S2 binding in Papio anubis measured in vivo with N-omega-[18F]fluoroethylketanserin and PET.
N-omega-[18F]fluoroethylketanserin ([18F]FEK), an 18F-labeled analogue of the serotonin S2 antagonist ketanserin, was evaluated for use with positron emission tomography (PET). PET imaging of a baboon brain following injection of [18F]FEK indicated that the fluorinated ligand rapidly localized in vivo within S2 receptor-rich tissues (frontal cortex/cerebellum radioactivity ratio = 2.5 after 15 min), and selective localization was retained for as long as 3 h post injection. Pretreatment with unlabeled ketanserin (15 mg/kg, i.v.) 1 h prior to [18F]FEK completely abolished selective localization of the radiotracer, whereas regional cerebral blood flow, cerebral blood volume, and the free fraction of [18F]FEK in arterial blood were unaltered. [18F]FEK has several advantages compared to previously used PET radiopharmaceuticals, and may be an excellent radioligand for non-invasive evaluation of S2 binding in vivo.
Moerlein
S M
SM
Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110.
Perlmutter
J S
JS
D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D005462:Fluorine Radioisotopes; D007650:Ketanserin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D009928:Organ Specificity; D010215:Papio; D011985:Receptors, Serotonin / Q000378:metabolism*; D014055:Tomography, Emission-Computed
D005462:Fluorine Radioisotopes; D011985:Receptors, Serotonin; C069523:N-2-fluoroethylketanserin; D007650:Ketanserin