Evaluation of [18 F]2FP3 in pigs and non-human primates

Hanne D Hansen, Cristian C Constantinescu, Olivier Barret, Matthias M Herth, Janus H Magnussen, Szabolcs Lehel, Agnete Dyssegaard, Julie Colomb, Thierry Billard, Luc Zimmer, Gilles Tamagnan, Gitte M Knudsen

9 Citationer (Scopus)

Abstract

So far, no suitable 5-HT7 R radioligand exists for clinical positron emission tomography (PET) imaging. [18 F]2FP3 was first tested in vivo in cats, and the results were promising for further evaluations. Here, we evaluate the radioligand in pigs and non-human primates (NHPs). Furthermore, we investigate species differences in 5-HT7 R binding with [3 H]SB-269970 autoradiography in post-mortem pig, NHP, and human brain tissue. Specific binding of [18 F]2FP3 was investigated by intravenous administration of the 5-HT7 R specific antagonist SB-269970. [3 H]SB-269970 autoradiography was performed as previously described. [18 F]2FP3 was synthesized in an overall yield of 35% to 45%. High brain uptake of the tracer was found in both pigs and NHPs; however, pretreatment with SB-269970 only resulted in decreased binding of 20% in the thalamus, a 5-HT7 R-rich region. Autoradiography on post-mortem pig, NHP, and human tissues revealed that specific binding of [3 H]SB-269970 was comparable in the thalamus of pig and NHP. Despite the high uptake of [18 F]2FP3 in both species, the binding could only be blocked to a limited degree with the 5-HT7 R antagonists. We speculate that the affinity of the radioligand is too low for imaging the 5-HT7 Rs in vivo and that part of the PET signal arises from targets other than the 5-HT7 R.

OriginalsprogEngelsk
TidsskriftJournal of Labelled Compounds and Radiopharmaceuticals
Vol/bind62
Udgave nummer1
Sider (fra-til)34-42
Antal sider9
ISSN0362-4803
DOI
StatusUdgivet - 1 jan. 2019

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