Characterization of Amyloid deposition in PSAPP mice

R1282 immunostaining demonstrated $A\beta$ deposition in cortical and hippocampal regions of PSAPP mice, as published previously [32]. In the 4 PSAPP mice utilized in this study, the percentage of cingulate cortex covered with R1282 immunoreactivity is $15.07\pm X$ %. ThioS staining deposits covers $1.50\pm X$ % of the cingulate cortex. The distribution of the sizes of the R1282 deposits as well as the ThioS staining deposits follow a peak distribution [33] that indicate a decrease in their number with deposit size (Fig. 3(a) and (c)).

Since we are interested in the role of $A\beta$ deposits in neuronal death, we evaluated the proportion of $A\beta$ deposits that overlapped NeuN staining neurons (presumably less toxic) and those that did not ($A\beta$ deposits that may have pushed away or killed neurons within the deposit). $70.8\pm X$ % of the R1282 immunoreactive coverage overlap NeuN staining, while $29.2\pm$ % does not. $18.2\pm X$ % of the total R1282 is ThioS positive. Although the percentage of R1282 not overlaping NeuN is independent of deposit size (Fig. 3(b)), the percentage of those R1282 deposits that are also ThioS positive increases with size (Fig. 3(b)).

Most ($89\pm X$ %) of the ThioS staining deposits did not overlap any NeuN staining neurons. The proportion of ThioS deposits that did not overlap NeuN staining neurons increased with the size of the deposit (Fig. 3(d)). The neuronal density by NeuN staining was on average $2400 neurons/\mu m^2$.