Off‐target screening of amyloid‐beta plaque targeting [18F]florapronol ([18F]FC119S) in postmortem Alzheimer's disease tissues

Abstract

AbstractWe investigated the off‐target binding of amyloid‐beta (Aβ) target [18F]florapronol ([18F]FC119S) using postmortem Alzheimer's disease (AD) brain tissue, compared with a known Aβ target imaging agent, [125I]TZDM and tau targeting [125I]MK as positive and negative controls, respectively. Off‐target binding of monoamine oxidase‐A and ‐B (MAO‐A and ‐B) was screened for FC119S and Pittsburgh compound B (PiB). Autoradiography (ARG) was performed to screen the Aβ‐binding potential using human AD postmortem brain tissue sections. Colocalization was quantitatively analyzed by using image analysis software. Pathological analysis was performed for screening of specific binding of amyloid‐beta and phospho‐tau. Amyloid‐beta targeting [18F]FC119S and [125I]TZDM tracers were showed a similar binding pattern in ARG, but [125I]MK was showed a different binding patterns. In the blocking experiment, [18F]FC119S binding was effectively blocked by a cold TZDM compound. FC119S and PiB were not showed specific binding with MAO‐A and MAO‐B. The autoradiographic binding pattern was positively correlated with the Aβ expression.