Figure 4. Reduction of brain AMPKα1 corrects AD-associated deficits in synaptic density and dendritic spine morphology.

(A) Classification of mature (mushroom, stubby, and branched) and immature (filopodia, long thin, and short thin) spine types on dendrite. Scale bar: 20 μm. (B) Representative images from Golgi-Cox stain of area CA1 dendritic spines and quantification of total (mature and immature) spine density. Tg and α2/Tg spines have significantly decreased spine density as compared with those in WT and α1/Tg mice. Scale bar: 5 μm (×100). ***P < 0.0001, 1-way ANOVA with Tukey’s post hoc test. F = 107.2. (C–E) Quantification of subclassification of mature spines. Tg and α2/Tg mice have significantly fewer stubby (F = 18.84), branched (F = 20.87), and mushroom (F = 64.33) spines than WT and α1/Tg mice. **P < 0.005; ***P < 0.0001, 1-way ANOVA with Tukey’s post hoc test. (F) Quantification of mature spine density. WT, n = 4; Tg, α1/Tg, and α2/Tg, n = 3. Spine length (200 μm) analyzed from 5 regions of interest (ROIs) per slice, 3 to 7 slices per mouse. ***P < 0.0001, 1-way ANOVA with Tukey’s post hoc test. (G) Representative TEM from hippocampal CA1 dendrites and quantification of postsynaptic densities (PSDs). n = 3 animals per group. Scale bar: 500 μm. Blue arrows indicate PSDs. Number of PSDs is significantly decreased in Tg and α2/Tg mice as compared with WT and α1/Tg mice. ***P < 0.0001, 1-way ANOVA with Tukey’s post hoc test. F = 49.77. (H) Western blot analysis of hippocampal lysate showed significantly reduced levels of PSD95 in Tg and α2/Tg mice compared with WT and α1/Tg mice. WT, n = 10; Tg, n = 9; α1/Tg, n = 6; α2/Tg, n = 7. *P = 0.0305; **P = 0.0047; Tg versus α1/Tg, ***P = 0.0006; Tg versus α2/Tg, ^#P < 0.0001, 1-way ANOVA with Tukey’s post hoc test. F = 9.572, noncongruous. Box-and-whisker plots represent the interquartile range, with the line across the box indicating the median. Whiskers show the highest and lowest values detected.