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

6 Citations (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.

Original languageEnglish
JournalJournal of Labelled Compounds and Radiopharmaceuticals
Volume62
Issue number1
Pages (from-to)34-42
Number of pages9
ISSN0362-4803
DOIs
Publication statusPublished - 1 Jan 2019

Keywords

  • 5-HT receptor
  • autoradiography
  • PET
  • [ F]2FP3
  • [ H]SB-269970

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