Comparative analysis of APP/APLP mutant mice reveals a reduction in spine density only in APP and APP/APLP2-DKO neurons. (a, b) Spine density counts were performed for either basal (a) or mid-apical (b) dendrites of CA1 neurons of the indicated genotypes and values expressed relative to APP-WT dendrites set as 100%. (a, b) Basal and apical dendrites from APP-KO and APP/APLP-DKO both show significant reductions in spine density, as compared to either WT or APLP2-KO mice. In contrast, APLP2-KO and APLP1-KO were unaffected. Note that spine density of APP/APLP2-DKO dendrites was not significantly different from that of APP-KO dendrites. Next, we compared WT and APLP1-KO neurons. Spine density of APLP1-KO neurons was comparable to WT neurons. Spine density was determined using n = 15-30 neurons/ genotype from 5-12 mice per genotype. All Values represent mean ± SEM, One-way ANOVA with Bonferroni multiple comparison test. Asterisks indicate statistically significant differences; ***p ≤ 0.001.