Radiopharmaceutical Evidence for MCHR1 Binding Sites in Murine Brown Adipocytes.

[C]SNAP-7941 and its radiofluorinated, fluoro-ethyl derivative [F]FE@SNAP have been developed as the first positron emission tomography tracers for melanin-concentrating hormone receptor 1 (MCHR1) imaging. Accumulation of these MCHR1 PET-tracers in rat brown adipose tissue (BAT) provided first indication of MCHR1 expression in rodent BAT. To rule out off-target binding, affinity of both MCHR1 ligands toward adrenergic beta-3 receptors (ADRB3) was examined.