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 σ1 selective imaging agent, [18F]FBFPA. The results of the study indicate that this radiotracer readily crosses the blood‐brain barrier and labels σ1 receptors in vivo. In vivo blocking studies with a σ1 selective ligand and a nonselective σ1/σ2 receptor ligand indicates that [18F]FBFPA labels σ1 and not σ2 receptors in rodent brain. PET imaging studies demonstrated a high uptake in regions of rhesus monkey brain having a high density of σ1 receptors. The uptake of [18F]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 [18F]FBFPA is a potential radiotracer for imaging σ1 receptors in the CNS in vivo with PET. Synapse 58:267–274, 2005. © 2005 Wiley‐Liss, Inc.