FIG. 3.
Amyloid-β plaque formation. Free-floating sagittal sections (each, 30 μm; 6-month-old mice) were immunohistochemically stained with human-specific anti-Aβ antibody (amino acids 1 to 17). Staining (both intracellular and extracellular) was widespread across the brain. The sections shown are from APPV717I-CT100 (A) and combined (B) mice, in which diffuse non-congophilic plaques are clearly visible. No plaques were visible in the brains of littermate wild-type mice (not shown). Scale bar, 100 μm. The immunohistochemical data are representative of four independent samples per group. The levels of human Aβ1-40 and Aβ1-42 present in SDS-soluble (soluble) and formic acid-extracted (insoluble) brain fractions from APPV717I-CT100 (grey bars) and combined (black bars) mice aged 6 and 12 months were analyzed by ELISA (C). Background wild-type levels were subtracted from each sample group and consisted of less than 10% of the total value obtained in each instance. The data are expressed as picomoles per gram of frozen brain sample weight and are the means ± SEM for four independent samples per group. Note the change of scale between the Aβ1-40 and Aβ1-42 ordinates.