[11C]SMe-ADAM, an imaging agent for the brain serotonin transporter: synthesis, pharmacological characterization and microPET studies in rats.
N,N-Dimethyl-2-(2-amino-4-methylthiophenylthio)benzylamine (SMe-ADAM, 1) is a highly potent and selective inhibitor of the serotonin transporter (SERT). This compound was labeled with carbon-11 by methylation of the S-desmethyl precursor 10 with [(11)C]methyl iodide to obtain the potential positron emission tomography (PET) radioligand [(11)C]SMe-ADAM. The radiochemical yield was 27 +/- 5%, and the specific radioactivity was 26-40 GBq/micromol at the end of synthesis. Ex vivo and in vivo biodistribution experiments in rats demonstrated a rapid accumulation of the radiotracer in brain regions known to be rich in SERT, such as the thalamus/hypothalamus region (3.59 +/- 0.41%ID/g at 5 min after injection). The specific uptake reached a thalamus to cerebellum ratio of 6.74 +/- 0.95 at 60 min postinjection. The [(11)C]SMe-ADAM uptake in the thalamus was significantly decreased by pretreatment with fluoxetine to 38 +/- 11% of the control value. Furthermore, no metabolites of [(11)C]SMe-ADAM could be detected in the SERT-rich regions of the rat brain. It is concluded that [(11)C]SMe-ADAM may be a suitable PET ligand for SERT imaging in the living brain.
Zessin
Jörg
J
Institut für Bioanorganische und Radiopharmazeutische Chemie, Forschungszentrum Rossendorf, Dresden, Germany. j.zessin@fz-rossendorf.de
Deuther-Conrad
Winnie
W
Kretzschmar
Marion
M
Wüst
Frank
F
Pawelke
Beate
B
Brust
Peter
P
Steinbach
Jörg
J
Bergmann
Ralf
R
D000814:Aniline Compounds / Q000493:pharmacokinetics*; D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism*; D002250:Carbon Radioisotopes; D008297:Male; D008657:Metabolic Clearance Rate; D009928:Organ Specificity; D049268:Positron-Emission Tomography / Q000379:methods* / Q000662:veterinary; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*; D013440:Sulfides / Q000493:pharmacokinetics*; D014018:Tissue Distribution
D000814:Aniline Compounds; D002250:Carbon Radioisotopes; C510968:N,N-dimethyl-2-(2-amino-4-methylthiophenylthio)benzylamine; D019275:Radiopharmaceuticals; D050486:Serotonin Plasma Membrane Transport Proteins; C493232:Slc6a4 protein, rat; D013440:Sulfides