Fig. 3.

Evaluation of the dendrites spines in TT, CT, AβPP+, and WT mice. A) Golgi staining shows similar gross visual morphology of neuron and dendritic branching for TT, CT, AβPP+ and WT mice at 6 months of age. Scale bar = 50 μm. B) Sholl analysis (i.e., method of concentric circles) for pyramidal neurons in the cortex reveals a significant effect of genotype (F(3,61) = 15.84, p < 0.000), distance from the soma (F(4,244) = 535.23, p < 0.0001), and a genotype x distance interaction (F(12,2444) = 1.83, p = 0.044) on dendritic arborization. The number of dendrite branches in the intersections was significantly decreased in TT mice starting at 60 μm from the soma. C) There is no difference in the number of the primary branches. D) Representative images of pyramidal neuron spines in the cortex of CT, TT, AβPP+ and WT mice from individual spines identified and counted under 100X magnification using stereological methods. Scale bar = 10 μm. E, F) A significant effect of genotype was found on spine density in the frontal cortex (E) (F(3,278) = 22.07, p < 0.0001), and hippocampus (F) (F(3,136) = 71.28, p < 0.0001). Spine density is expressed as number of spines per 10 μm dendrite length. Post-hoc testing showed significant decreases spine density in CT, TT, and AβPP+ mice as compared to WT mice (p < 0.01) in the frontal cortex and hippocampus, with TT mice having lower values as compared to CT and AβPP+ mice (p < 0.05) (*p < 0.05 compared to WT; ^#p < 0.05 compared to CT and AβPP+ mice). G) No effect of genotype was observed on spine density in the thalamus.