(A and B) Representative immunoblots (A) and densitometry analysis (B) of ROCK2 and phosphorylated LIMK1 protein abundance in the hippocampus of hAPPJ20 mice relative to each in non-transgenic (NTG) littermates. For densitometry, pLIMK1 was normalized to levels of LIMK1. Immunoblot for amyloid precursor protein (APP) identifies human APP in hAPPJ20 mice. Data are means ± SEM of 7 mice (3 males and 4 females per genotype). *P<0.05 (actual P=0.0191) and ***P<0.001 (actual P=0.0007) by an unpaired t-test. (C) Representative maximum-intensity image of a CA1 pyramidal neuron in the hippocampus iontophoretically-filled with Lucifer yellow. Blue signal is DAPI. Scale bar, 50 μm. (D) Representative maximum-intensity high-resolution confocal microscope images of dye-filled dendrites, from mock- or SR7826-treated hAPPJ20 and NTG mice, after deconvolution and corresponding three-dimensional digital reconstruction models of dendrites. Scale bar, 5 μm. Colors in digital reconstructions correspond to dendritic protrusion classes: blue represents thin spines; orange, stubby spines; green, mushroom spines; and yellow, dendritic filopodia. (E and F) Mean number of apical (E) and basal (F) spines per 10 μm in dendrites from mock- or SR7826-treated hAPPJ20 and NTG mice. Data are means ± SEM. The apical dendrite conditions are as follows: N=26 dendrites from 5 NTG mock mice (3 females, 2 males), N=26 dendrites from 5 NTG SR7826 mice (1 female, 4 males), N=33 dendrites from 5 hAPPJ20 mock mice (2 females, 3 males), and N=30 dendrites from 5 hAPPJ20 SR7826 mice (2 females, 3 males) for a total of 3,546 μm analyzed. The basal dendrite conditions are as follows: N=22 dendrites from 5 NTG mock mice (3 females, 2 males), N=23 dendrites from 5 NTG SR7826 mice (1 female, 4 males), N=26 dendrites from 5 hAPPJ20 mock mice (2 females, 3 males), and N=26 dendrites from 5 hAPPJ20 SR7826 mice (2 females, 3 males) for a total of 3,126 μm analyzed. *P<0.05 (actual P=0.0313) and ***P<0.001 (actual P=0.0005) by one-way ANOVA with Sidak’s test. (G and H) Mean number of thin, stubby, or mushroom spines per 10 μm of apical (G) or basal (H) dendrites from mock- or SR7826-treated hAPPJ20 and NTG mice. Data are means ± SEM; N as given in (E and F). *P<0.05 (actual P=0.0398), **P<0.01 (actual P=0.0098), ***P<0.001 (actual P=0.0002), and ****P<0.0001 by two-way ANOVA with Tukey’s test. (I and J) Mean spine length of apical (I) and basal (J) spines among CA1 pyramidal neurons in the hippocampus from mock- or SR7826-treated hAPPJ20 and NTG mice. Data are means ± SEM; N as given in (E and F). ***P<0.001 (actual P=0.0003) and ****P<0.0001 by one-way ANOVA with Sidak’s test.