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Radiosynthesis and in vivo evaluation of a series of substituted 11C-phenethylamines as 5-HT (2A) ag

Radiosynthesis and in vivo evaluation of a series of substituted 11C-phenethylamines as 5-HT (2A) ag

  1. lostmente
    One of the first professional publications regarding compound 25C-NBOME and other analogues

    Abstract
    Purpose Positron emission tomography (PET) imaging of
    serotonin 2A (5-HT2A) receptors with agonist tracers holds
    promise for the selective labelling of 5-HT2A receptors in their
    high-affinity state. We have previously validated [
    11
    C]Cimbi-5
    and found that it is a 5-HT2A receptor agonist PET tracer. In an
    attempt to further optimize the target-to-background binding
    ratio, we modified the chemical structure of the phenethylamine backbone and carbon-11 labelling site of [
    11
    C]Cimbi-5
    in different ways. Here, we present the in vivo validation of nine
    novel 5-HT2A receptor agonist PET tracers in the pig brain.
    Methods Each radiotracer was injected intravenously into
    anaesthetized Danish Landrace pigs, and the pigs were
    subsequently scanned for 90 min in a high-resolution
    research tomography scanner. To evaluate 5-HT2A receptor
    binding, cortical nondisplaceable binding potentials (BPND)
    were calculated using the simplified reference tissue model
    with the cerebellum as a reference region.
    Results After intravenous injection, all compounds entered
    the brain and distributed preferentially into the cortical
    areas, in accordance with the known 5-HT2A receptor
    distribution. The largest target-to-background binding ratio
    was found for [
    11
    C]Cimbi-36 which also had a high brain
    uptake compared to its analogues. The cortical binding of
    [
    11
    C]Cimbi-36 was decreased by pretreatment with ketanserin, supporting 5-HT2A receptor selectivity in vivo. [
    11
    C]
    Cimbi-82 and [
    11
    C]Cimbi-21 showed lower cortical BPND,
    while [
    11
    C]Cimbi-27, [
    11
    C]Cimbi-29, [
    11
    C]Cimbi-31 and
    [
    11
    C]Cimbi-88 gave rise to cortical BPND similar to that of
    [
    11
    C]Cimbi-5.
    Conclusion [
    11
    C]Cimbi-36 is currently the most promising
    candidate for investigation of 5-HT2A receptor agonist
    binding in the living human brain with PET