N-[18F]4′-fluorobenzylpiperidin-4yl(2-fluorophenyl) acetamide ([18F]FBFPA):: A potential fluorine-18 labeled PET radiotracer for imaging sigma-1 receptors in the CNS

A series of brain uptake studies and PET imaging studies were conducted with the a, selective imaging agent, [F-18]FBFPA. The results of the study indicate that this radiotracer readily crosses the blood-brain barrier and labels sigma(1) receptors in vivo. In vivo blocking studies with a sigma(1) selective ligand and a nonselective sigma(1)/sigma(2) receptor ligand indicates that [F-18]FBFPA labels sigma(1) and not sigma(2) receptors in rodent brain. PET imaging studies demonstrated a high uptake in regions of rhesus monkey brain having a high density of sigma(1) receptors. The uptake of [F-18]FBFPA was displaced by the sigma ligand, haloperidol (1 mg/kg, i.v.). In vivo blocking studies indicate that the progesterone blocked the brain uptake of [18F]FBFPA in rat brain. These data indicate that [F-18]FBFPA is a potential radiotracer for imaging sigma(1) receptors in the CNS in vivo with PET.