title: Specific in vivo binding to the norepinephrine transporter demonstrated with the PET radioligand, (S,S)-[11C]MeNER.
abstract: (S,S)-2-(alpha-(2-Methoxyphenoxy)benzyl)morpholine (MeNER), an O-methyl analog of the selective and potent norepinephrine transporter (NET) inhibitor, (S,S)-reboxetine, and its less active enantiomer, (R,R)-MeNER, have each been radiolabeled by O-methylation of their corresponding phenolic precursors in good yields from [(11)C]methyl iodide or [(11)C]methyl triflate. Radiochemical purities were >99% and specific radioactivity at time of injection was about 74 GBq/micromol. Autoradiographic examination of (S,S)-[(11)C]MeNER binding to human brain slices post mortem indicated specific binding in a brain region including the locus coeruleus. PET examination of both [(11)C]MeNER enantiomers in a cynomolgus monkey demonstrated a higher specific binding of the (S,S)-enantiomer with ratios of 1.4-1.6 in the lower brainstem, mesencephalon and thalamus to striatum. Pretreatment with the NET ligand, desipramine, decreased the specific binding of (S,S)-[(11)C]MeNER. Labeled metabolites of [(11)C]MeNER were all more polar. (S,S)-[(11)C]MeNER is a good lead compound in the search for a selective radioligand for quantitation of NET in the human brain in vivo.
mesh_terms: D000818:Animals; D001345:Autoradiography / Q000379:methods*; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism*; D002102:Cadaver; D046508:Culture Techniques; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D008252:Macaca fascicularis; D008657:Metabolic Clearance Rate; D009025:Morpholines / Q000097:blood / Q000493:pharmacokinetics*; D050484:Norepinephrine Plasma Membrane Transport Proteins; D019275:Radiopharmaceuticals / Q000097:blood / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D027981:Symporters / Q000378:metabolism*; D014018:Tissue Distribution; D014055:Tomography, Emission-Computed / Q000379:methods*
chemical_list: C483610:2-(alpha-(2-methoxyphenoxy)benzyl)morpholine; D009025:Morpholines; D050484:Norepinephrine Plasma Membrane Transport Proteins; D019275:Radiopharmaceuticals; C493227:SLC6A2 protein, human; D027981:Symporters