PS1 downregulation in new neurons decreases dendritic arborization and spine density.

<p><b>A</b>. Compressed Z-stack confocal images (Zeiss LSM 510) of newly mature GFP⁺ neurons (GFP⁺BrdU+NeuN⁺) in the granular cell layer of the dentate gyrus of RL shRNA- and PS1 shRNA- injected mice 6 months after injection. Images show a dramatic decrease in the number of dendritic arborization in mature GFP⁺ neurons in the PS1 shRNA- injected mice. <b>B</b>. Sholl analysis of the number of intersections measured from n = 16 neurons per group. PS1 animals show decreased number of intersections (two-way ANOVA (treatment and distance from soma) F_{(treatment)1,120} = 14.75, P<0.001, F_{(distance)19,120} = 4.10, P<0.0001). <b>C, D</b>. PS1 downregulation results in decreased number of spines <b>(C)</b> as a function of increasing distance from the soma (two-way ANOVA (treatment and distance from soma) F_{(treatment)1,60} = 13.10, P<0.001, F_{(distance)19,60} = 3.18, P<0.001) and mean spine density <b>(D)</b> (unpaired t-test, *P<0.05). <b>F, G</b>. Dendritic surface area (<b>F)</b> and volume <b>(G)</b> were unaffected by PS1 downregulation. Error bars indicate ±SEM.