Fig. 2.

Intra-cerebral injection of brain homogenate from an old Tg2576 mouse into young mice induces substantial Aβ deposition. a Representative pictures of 4G8 stained brain slices from Tg2576 (n = 4–5) intra-cerebrally injected with PBS or 10% brain homogenate obtained from a 12 months old Tg2576 mouse harboring amyloid plaques (left and middle panels, respectively). Two different magnifications are shown. The scale bars in top and bottom panels correspond to 300 μm and 20 μm, respectively. The dashed squares in top panels represent the area depicted in bottom panels. The picture in the right corresponds to an animal subjected to 2 transfusions with Tg-blood (Experiment 1). The magnified image in “Tg (10% BH)” was obtained from a consecutive brain slice and display the same highlighted plaques. b Number of Aβ reactive plaques, which was expressed as number of plaques per mm² of the brain area analyzed. c The area of antibody-reactive Aβ deposits in each group was measured and divided by the total brain area analyzed (Aβ burden). The values are expressed as a percentage and multiplied by 1000. d The quantity of insoluble Aβ₄₂ was measured using ELISA kits after formic acid extraction, as described in “Materials and methods” section. For panels b–d, values on untreated animals are shown as reference. The values showed in the graphs are expressed as mean ± SEM of the different animals used in each group. *P < 0.05, **P < 0.01, ***P < 0.001 based on ANOVA followed by the Tukey’s multiple comparison post hoc test