Amyloid tracers binding sites in autosomal dominant and sporadic Alzheimer's disease.

INTRODUCTION: Amyloid imaging has been integrated into diagnostic criteria for Alzheimer's disease (AD). How amyloid tracers binding differ for different tracer structures and amyloid-β aggregates in autosomal dominant AD (ADAD) and sporadic AD is unclear.

METHODS: Binding properties of different amyloid tracers were examined in brain homogenates from six ADAD with APPswe, PS1 M146V, and PS1 EΔ9 mutations, 13 sporadic AD, and 14 control cases.

RESULTS: (3)H-PIB, (3)H-florbetaben, (3)H-AZD2184, and BTA-1 shared a high- and a varying low-affinity binding site in the frontal cortex of sporadic AD. AZD2184 detected another binding site (affinity 33 nM) in the frontal cortex of ADAD. The (3)H-AZD2184 and (3)H-PIB binding were significantly higher in the striatum of ADAD compared to sporadic AD and control. Polyphenol resveratrol showed strongest inhibition on (3)H-AZD84 binding followed by (3)H-florbetaben and minimal on (3)H-PIB.

DISCUSSION: This study implies amyloid tracers of different structures detect different sites on amyloid-β fibrils or conformations.