Serotonin 2A receptor agonist binding in the human brain with [(11)C]Cimbi-36: Test-retest reproducibility and head-to-head comparison with the antagonist [(18)F]altanserin

Neuroimage. 2016 Apr 15:130:167-174. doi: 10.1016/j.neuroimage.2016.02.001. Epub 2016 Feb 11.

Abstract

Introduction: [(11)C]Cimbi-36 is a recently developed serotonin 2A (5-HT2A) receptor agonist positron emission tomography (PET) radioligand that has been successfully applied for human neuroimaging. Here, we investigate the test-retest variability of cerebral [(11)C]Cimbi-36 PET and compare [(11)C]Cimbi-36 and the 5-HT2A receptor antagonist [(18)F]altanserin.

Methods: Sixteen healthy volunteers (mean age 23.9 ± 6.4years, 6 males) were scanned twice with a high resolution research tomography PET scanner. All subjects were scanned after a bolus of [(11)C]Cimbi-36; eight were scanned twice to determine test-retest variability in [(11)C]Cimbi-36 binding measures, and another eight were scanned after a bolus plus constant infusion with [(18)F]altanserin. Regional differences in the brain distribution of [(11)C]Cimbi-36 and [(18)F]altanserin were assessed with a correlation of regional binding measures and with voxel-based analysis.

Results: Test-retest variability of [(11)C]Cimbi-36 non-displaceable binding potential (BPND) was consistently <5% in high-binding regions and lower for reference tissue models as compared to a 2-tissue compartment model. We found a highly significant correlation between regional BPNDs measured with [(11)C]Cimbi-36 and [(18)F]altanserin (mean Pearson's r: 0.95 ± 0.04) suggesting similar cortical binding of the radioligands. Relatively higher binding with [(11)C]Cimbi-36 as compared to [(18)F]altanserin was found in the choroid plexus and hippocampus in the human brain.

Conclusions: Excellent test-retest reproducibility highlights the potential of [(11)C]Cimbi-36 for PET imaging of 5-HT2A receptor agonist binding in vivo. Our data suggest that Cimbi-36 and altanserin both bind to 5-HT2A receptors, but in regions with high 5-HT2C receptor density, choroid plexus and hippocampus, the [(11)C]Cimbi-36 binding likely represents binding to both 5-HT2A and 5-HT2C receptors.

Keywords: 5-HT; Agonist; Neuroimaging; Positron emission tomography; Radiotracer evaluation; Test–retest variability.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzylamines / metabolism
  • Benzylamines / pharmacokinetics*
  • Brain / metabolism*
  • Carbon Radioisotopes / metabolism
  • Carbon Radioisotopes / pharmacokinetics
  • Female
  • Fluorine Radioisotopes / metabolism
  • Fluorine Radioisotopes / pharmacokinetics
  • Humans
  • Ketanserin / analogs & derivatives*
  • Ketanserin / metabolism
  • Ketanserin / pharmacokinetics
  • Male
  • Neuroimaging / methods
  • Phenethylamines / metabolism
  • Phenethylamines / pharmacokinetics*
  • Positron-Emission Tomography / methods
  • Radiopharmaceuticals / metabolism
  • Radiopharmaceuticals / pharmacokinetics
  • Reproducibility of Results
  • Serotonin 5-HT2 Receptor Agonists / metabolism
  • Serotonin 5-HT2 Receptor Agonists / pharmacokinetics*
  • Serotonin 5-HT2 Receptor Antagonists / metabolism
  • Serotonin 5-HT2 Receptor Antagonists / pharmacokinetics*
  • Young Adult

Substances

  • Benzylamines
  • Carbon Radioisotopes
  • Cimbi-36
  • Fluorine Radioisotopes
  • Phenethylamines
  • Radiopharmaceuticals
  • Serotonin 5-HT2 Receptor Agonists
  • Serotonin 5-HT2 Receptor Antagonists
  • altanserin
  • Ketanserin