Development of a carbon-11 PET radiotracer for imaging TRPC5 in the brain

Org Biomol Chem. 2019 Jun 5;17(22):5586-5594. doi: 10.1039/c9ob00893d.

Abstract

The transient receptor potential channel subfamily member 5 (TRPC5) is a calcium permeable cation channel widely expressed in the brain. Accumulating evidence indicates that it plays a crucial role in psychiatric disorders including depression and anxiety. Positron emission tomography (PET) combined with a TRPC5 specific radioligand may provide a unique tool to investigate the functions of TRPC5 in animal disease models to guide drug development targeting TRPC5. To develop a TRPC5 PET radiotracer, the potent TRPC5 inhibitor HC608 was chosen for C-11 radiosynthesis through the N-demethyl amide precursor 7 reacting with [11C]methyl iodide. Under optimized conditions, [11C]HC608 was achieved with good radiochemical yield (25 ± 5%), high chemical and radiochemical purity (>99%), and high specific activity (204-377 GBq μmol-1, decay corrected to the end of bombardment, EOB). The in vitro autoradiography study revealed that [11C]HC608 specifically binds to TRPC5. Moreover, initial in vivo evaluation of [11C]HC608 performed in rodents and the microPET study in the brain of non-human primates further demonstrated that [11C]HC608 was able to penetrate the blood brain barrier and sufficiently accumulate in the brain. These results suggest that [11C]HC608 has the potential to be a PET tracer for imaging TRPC5 in vivo.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brain / diagnostic imaging*
  • Carbon Radioisotopes
  • Humans
  • Positron-Emission Tomography*
  • Radiopharmaceuticals / chemical synthesis
  • Radiopharmaceuticals / chemistry*
  • Radiopharmaceuticals / pharmacokinetics
  • TRPC Cation Channels / analysis*
  • Tissue Distribution

Substances

  • Carbon Radioisotopes
  • Carbon-11
  • Radiopharmaceuticals
  • TRPC Cation Channels
  • TRPC5 protein, human