TY - JOUR
T1 - Radiosynthesis and in vivo evaluation of a series of substituted 11C-phenethylamines as 5-HT (2A) agonist PET tracers
AU - Ettrup, Anders
AU - Hansen, Martin
AU - Santini, Martin A
AU - Paine, James Stephen
AU - Gillings, Nicolas
AU - Palner, Mikael
AU - Lehel, S
AU - Herth, Matthias M
AU - Madsen, Jacob
AU - Kristensen, Jesper
AU - Begtrup, Mikael Erik
AU - Knudsen, Gitte M
PY - 2011/4
Y1 - 2011/4
N2 - 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 [11C]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 [ 11C]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-HT 2A 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 [11C]Cimbi-36 which also had a high brain uptake compared to its analogues. The cortical binding of [11C]Cimbi-36 was decreased by pretreatment with ketanserin, supporting 5-HT2A receptor selectivity in vivo. [11C]Cimbi-82 and [11C]Cimbi-21 showed lower cortical BPND, while [11C]Cimbi-27, [11C]Cimbi- 29, [11C]Cimbi-31 and [11C]Cimbi-88 gave rise to cortical BPND similar to that of [11C]Cimbi-5. Conclusion: [ 11C]Cimbi-36 is currently the most promising candidate for investigation of 5-HT2A receptor agonist binding in the living human brain with PET.
AB - 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 [11C]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 [ 11C]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-HT 2A 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 [11C]Cimbi-36 which also had a high brain uptake compared to its analogues. The cortical binding of [11C]Cimbi-36 was decreased by pretreatment with ketanserin, supporting 5-HT2A receptor selectivity in vivo. [11C]Cimbi-82 and [11C]Cimbi-21 showed lower cortical BPND, while [11C]Cimbi-27, [11C]Cimbi- 29, [11C]Cimbi-31 and [11C]Cimbi-88 gave rise to cortical BPND similar to that of [11C]Cimbi-5. Conclusion: [ 11C]Cimbi-36 is currently the most promising candidate for investigation of 5-HT2A receptor agonist binding in the living human brain with PET.
U2 - 10.1007/s00259-010-1686-8
DO - 10.1007/s00259-010-1686-8
M3 - Journal article
SN - 1619-7070
VL - 38
SP - 681
EP - 693
JO - European Journal of Nuclear Medicine and Molecular Imaging
JF - European Journal of Nuclear Medicine and Molecular Imaging
IS - 4
ER -