Figure 2.

Autoradiographic labelling of Alzheimer’s disease hippocampal formation sections with ¹¹C-PBB3 and ¹⁸F-AV-1451, followed by histochemical and immunohistochemical microscopic assays. (A) Autoradiographic labelling of closely adjacent brain sections of a patient with Alzheimer’s disease with 5 nM of ¹¹C-PBB3 (left) and ¹⁸F-AV-1451 (right) in the absence (top) and presence (bottom) of 100 µM of non-radioactive PBB5. Slices contain the hippocampal CA1 sector (1), subiculum (2), presubiculum sectors close to the subiculum (3) and parasubiculum (4), and entorhinal cortex (5). (B) Ratio of ¹¹C-PBB3 (filled bars) and ¹⁸F-AV-1451 (open bars) autoradiographic signal intensity in a target area to a white matter value estimated in sections shown in A. (C) Triple labelling of the section used for ¹¹C-PBB3 autoradiography (shown in A) with GB, AT8 and N1D. Areas correspond to locations indicated by squares in A. The hippocampal CA1 sector (1) contained abundant ghost tangles, non-ghost tangles and neuritic plaques. The subiculum (2) harboured abundant ghost tangles and a fewer number of non-ghost tangles and neuritic plaques. The presubiculum adjacent to the subiculum (3) showed a small number of ghost tangles, non-ghost tangles and neuropil threads. The presubiculum in proximity to the parasubiculum (4) was enriched with highly diffuse amyloid-β deposits with few tau lesions. The entorhinal cortex (5) contained abundant ghost tangles. Immunolabelling of the section used for ¹⁸F-AV-1451 autoradiography also revealed tau and amyloid-β lesions similar to the above-mentioned findings (data not shown). (D) Low-power photomicrographs of closely adjacent sections of a presubicular sector flanking the subiculum stained with 56.5 µM of PBB3 (left) and AV-1451 (right). Scale bars = 20 µm (A, C and D).