Figure 5

Impairments in synaptic number and synaptic proteins are related to Aβ overexpression via AAV-mediated gene transfer. (a–d) Stereological quantification showed a significant decrease in total spines for the AAV-BRI- Aβ42 and AAV-UBI- Aβ42 groups (67.65% ± 5.06; 43.02% ± 4.93; *p < 0.0001) when compared to AAV-EGFP-transfected mice. There was also a significant decrease in mushroom (BRI-Aβ42: 44.09% ± 4.83; UBI-Aβ42: 40.13% ± 9.78; *p = 0.0021), stubby (BRI-Aβ42: 62.34% ± 4.20, *p = 0.0015) and filopodia-like spines (BRI-Aβ42: 76.72% ± 0.59; UBI-Aβ42: 62.53% ± 8.42; *p < 0.0001) compared to the number observed in EGFP-transfected mice. Notably, there was no significant difference in stubby spines in the AAV-UBI-Aβ42 group. The values represent the mean ± SEM (n = 5 per group). (e) Light microscopic 3D reconstruction images of dendritic spines in the CA1 subfield in AAV-EGFP, AAV-BRI- Aβ42 and AAV-UBI- Aβ42 mice. (f–i) Immunoblot analysis of hippocampal homogenates of 8–9 month-old mice, normalized to GAPDH and expressed as arbitrary units, showing a significant reduction in the expression of PSD-95 (BRI-Aβ42: 37.20% ± 9.19; UBI-Aβ42: 44.80% ± 5.35; *p = 0.0028), synaptophysin (BRI-Aβ42: 43.69% ± 9.75; UBI-Aβ42: 39.82% ± 6.46; *p = 0.0030) and profilin-1 (BRI-Aβ42: 51.87% ± 8.00; UBI-Aβ42: 42.04% ± 11.13; *p = 0.0075) compared to the EGFP group. Quantification of western blots was performed via densitometric analysis and is presented as arbitrary units, normalized to GAPDH. Colored circles represent the groups tested: white - EGFP; yellow - BRI-Aβ42; blue - UBI-Aβ42. Values represent the mean ± SEM (n = 4 per group).