Presentation Radiolabelling of Super-diffuse Amyloid-b Deposition with Popularly Used Amyloid Imaging Ligands in Postmortem Brain of Alzheimer’s Disease

BinJi  ,  Chun-Jen, Chen  ,  Bando, Kazunori  ,  Ashino, Hiroki  ,  Ono, Maiko  ,  Minamihisamatsu, Takeharu  ,  Suhara, Tetsuya  ,  Higuchi, Makoto

Background/Purpose: We have successfully visualized amyloid- (A) deposition in a mouse model of Alzheimer’s disease (AD) with the aid of newly developed amyloid imaging tracer 123/125I-DRM106, and suggested different binding site in aggregated A for this compound with popularly used amyloid imaging tracers such as PiB (Pittsburgh Compound B) in our previous study (J Nucl Med; 2015). In the present study, we have investigated the autoradiogram of radioiodinated DRM106 and other several amyloid imaging tracers in postmortem AD brain to examine the possibility of distinguishing different types of A deposits by combination of these tracers. Materials & Methods: The AD brain sections containing the hippocampal and parahippocampal regions were incubated with radioactive tracers (11C-PiB; 5nM, 3H-AZD2184; 5nM, 125I-DRM106; 5nM) for 60 minutes, followed by consequent processes of autoradiographic analysis. Amyloid deposition was determined by fluorescent counterstaining with FSB and immunohistochemical staining with anti-A antibody (6E10). Results: Autoradiographic images showed there is greatly difference in the feature of binding to brain subregions between tested tracers. There were greatly abundant binding sites for 11C-PiB and 3H-AZD2184, but not for 125I-DRM106, in the presubiculum of AD brain, where, abundant super-diffuse A deposits reacted with 6E10, was FSB-negative by fluorescent microscopic observation. These data indicate preferentiality of DRM106 to highly maturated A deposits compared with PiB and AZD2184.Conclusions: The present result reveal possible contribution of those minor A pathology, such as super-diffuse plaques, to binding sites for these popularly used tracers, and it might be distinguishable by combination scans with different type amyloid imaging tracers such as PiB/AZD2184 and DRM106.
Japan-China Nuclear Medicine joint symposium in Okinawa

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