Potential of [11C]DASB for measuring endogenous serotonin with PET:: binding studies

The serotonin transporter radioligand [C-11]-3-amino-4-(2-dimethylaminomethylphenylsulfanyl)-benzonitrile, or [C-11]DASB, was examined in order to assess its potential for measuring fluctuations in endogenous serotonin concentrations with positron emission tomography. Binding characteristics of [C-11]DASB and the propensity for serotonin to displace the tracer were explored in rat brain homogenates. Experiments showed that serotonin displaced [C-11]DASB in vitro. Ex vivo experiments performed after tranylcypromine injection (3 or 15 mg/kg) showed a dose-dependent trend in radioactivity uptake and suggested that serotonin may compete with [C-11]DASB for transporter binding. (c) 2005 Elsevier Inc. All rights reserved.