Presentation Classification of Amyloid Imaging Ligands Based on Binding Characteristic in Presubiculum of Alzheimer’s Disease

季, 斌

Non-invasive determination of amyloid-beta peptide (Abeta) deposition with radioligands has important significance for early diagnosis and clarification of pathogenetic mechanisms of Alzheimer’s disease (AD). The polymorphic binding site on multimeric Abeta for current radioligands, however, is poorly understood. In the present study, we investigated the binding sites for several radioligands including 11C-Pittsburgh Compound B (11C-PiB), 3H-AZD2184, and two recently developed compounds, 125I-DRM106 and 125I-DRK092, in a unique presubicular Abeta deposits lacking reactivity with popularly used amyloid-affinity dyes including thioflavin-S, Congo Red and FSB. 11C-PiB, 3H-AZD2184 and 125I-DRK092 showed overt binding to the presubicular A deposits, while 125I-DRM106 was barely reactive with these aggregates, despite its strong binding in the hippocampal CA1 sector. Unlike neuritic plaques in the CA1, Abeta lesions in the presubiculum were not accompanied by inflammatory gliosis enriched with 18-kDa translocator protein (TSPO). Thus, there are at least two different components in Abeta aggregates providing distinct binding sites for the current amyloid radioligands, and one of these binding elements is purely present in the presubicular Abeta deposits. Amyloid radioligands lacking affinity for this component, such as 125I-DRM106, may selectively capture Abeta deposits tightly associated with TSPO-positive neuroinflammation and neurodegeneration as exemplified by CA1 neuritic plaques. The present study proposed binding affinity for the CA1 and presubicular Abeta deposits as a classification criteria and which would serve for developing an amyloid PET imaging agent visualizing neurotoxicity-related Abeta pathologies.
ANMAF 2016

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