PMC

Group 1 was intracerebrally seeded at 3 months of age, and analysed at 9 months; Group 2 was seeded at 9 months of age and analysed at 15 months; Group 3 was seeded at 3 months of age and analysed at 15 months.

(a) Twelve months after intracerebral injections of the Tg extract, copious Aβ was deposited in the brain (shown are coronal sections of the mouse presented in ; the coordinates from bregma A–P are indicated). Note that Aβ deposition was widespread throughout the neocortex and hippocampus, although Tg extract was injected only locally into the hippocampus and overlying cortex at AP −2.5mm. (b) Aβ load in each section from anterior to posterior is shown for the 12-month incubation mice (group 3) and compared to the 6-month incubation mice (group 1 &2) (section 1 to section 11; approximate location from bregma A–P is as follows, section 1= AP +2.2mm, section 5=AP +0.1mm, section 8= AP −1.8mm, section 11=AP −3.3mm). Note that the induced Aβ is highest around the injection site (corresponding to sections 9&10) in all groups, and that the Aβ deposits have spread throughout the brain, including the most anterior parts. Scale bar = 500 μm.

(a) Human APP and Aβ levels in the brains of R1.40 mice at multiple ages. (3 months [n=6; 3 male, 3 female], 9 months [n=6; 3 male, 3 female] and 15 months [n=6; 3 male, 3 female]). Shown are immunoblots, using antibody 6E10, of three mice/age group; GAPDH served as a loading control. (b) Quantification of protein levels in all mice revealed no difference among the groups (one-way ANOVA for APP and Aβ; both p>0.05). Three samples in each age group were applied to 1 gel, and 2 gels were used in total. Densitometric values of band intensities were analysed using ImageJ 1.44, and percentages relative to the amount in 3month-old mice were calculated from the average value at 3 months of age. (c) No Aβ deposition was found in the brains of 3-and 9-month-old R1.40 mice by immunohistochemical analysis, while in two of six 15-month-old mice, infrequent Aβ deposits were present in the frontal cortex. Scale bar = 500 μm.

(a) Induction of Aβ deposition was evident in all three groups of R1.40 mice that were intracerebrally seeded with the Tg extract, but not with the Wt extract. While the β-amyloid induction was similar in groups 1 and 2, Aβ load was greatest in Group 3. Adjacent sections were double-stained with Congo red and GFAP or Iba-1. While in groups 1 and 2, all induced β-amyloid was Congo red-negative, group 3 showed at least some Congo red-positive deposits surrounded by darkly stained and hypertrophic GFAP-positive astrocytes (insert, left) and Iba1-positive microglia (insert, right). (b) Quantitative stereological analysis. Group 1 (WT extract: n=5 [3 female, 2 male], Tg extract: n=7 [4 female, 3 male]); Group 2 (WT extract injected: n=6 [2 female, 4 male], Tg extract: n=6 [2 female, 4 male]); Group 3 (WT extract: n=5 [2 female, 3 male], Tg extract: n=4 [3 female, 1 male]). 3-way ANOVA for Gender × Group × Extract revealed significant main effects for Group and Extract (p<0.001) but no significant effect of gender (p>0.05). There was a significant Group × Extract interaction (F[2,21]=89.23; p<0.001) and subsequent Scheffé post hoc analyses were used to pinpoint group differences (*; p<0.05, **; p<0.01, ***; p<0.001). Scale bar = 500 μm and 10 μm.