The number of amyloid plaques and amount of Aβ_1-42 were reduced in S100A9 KO/Tg mice.

<p>After the tests, the mice brains were isolated and the brain slices were stained with Congo red for the detection of amyloid plaques. (A) Histological analysis was performed out at the age of 14-months. In the cortex, hippocampus and entorhinal cortex, amyloid plaques were detected using Congo red staining. (i)-(l) The Congo red-stained region of (c), (g) and (h). Thio-S stained region of (m). Sections are 4 µm thick. ((a) – (h) Scale bar; 200 µm, (i)-(l) scale bar; 50 µm). (B) Quantitative analysis of Congo red-stained plaque number. The number of amyloid plaques was counted in brain slices containing the hippocampal region of each group, and the average number of plaques per brain slice was calculated. In brains from the KO/Tg group, Aβ deposition was significantly reduced in the cortex and hippocampus, compared to the WT/Tg group. The total numbers of mice per group were as follows: n = 3–6 per group.<i>*p</i><0.05 by one-way ANOVA. (C, D) Western blot analysis was performed with the total lysates from the cortical region and hippocampal region of brains in each group using the 6E10 antibody. Aβ and CT bands were detected and normalized by the amount of APP and GAPDH. In the WT/Tg mice brain, many Aβ and CT were produced compared to KO/Tg mice. (n = 10). (E, F) Aβ<b>_1-42</b> levels in cortical or hippocampal brain regions in all groups were analyzed by Aβ ELISA. The levels of Aβ<b>_1-42</b> were highly increased in the cortex and hippocampus of WT/Tg mice compared with age-matched WT/WT or WT/KO mice. Note that the levels of Aβ<b>_1-42</b> were decreased in the cortex and hippocampus of KO/Tg mice brains compared with WT/Tg mice brains (n = 4). (G, H) Western blot analysis was performed with total lysates from the cortical region of the brains in each group using an antibody against oligomeric Aβ. In the cortex of KO/Tg mice brains, the relative quantity of oligomeric Aβ was decreased compared with WT/Tg mice. (n = 3) <i>*p</i><0.05 by one-way ANOVA.