α-Syn expression modulates pathology spread after AD-tau extract injection. (A–E) Representative images for AT8 p-tau pathology in tissue sections from the rostral and caudal hippocampus (A), entorhinal cortex (B), retrosplenial cortex (C), auditory cortex (D), and supramammillary nucleus (E) of WT and α-synKO mice 3, 6, or 9 mpi of AD-tau–enriched extracts. Scale bar, 100 µm. (F–O) Quantification of p-tau seen in A–E in the ipsilateral (F) and contralateral (G) hippocampus, ipsilateral (H) and contralateral (I) entorhinal cortex, ipsilateral (J) and contralateral (K) retrosplenial cortex, ipsilateral (L) and contralateral (M) auditory cortex, and ipsilateral (N) and contralateral (O) supramammillary nucleus. A two-tailed t test was performed to calculate the difference between groups; *, P < 0.05; **, P < 0.01; ****, P < 0.0001. Data are presented as mean ± SEM (n = 5–9 mice per group). (P) Semiquantitative heat mapping of p-tau pathology in WT and α-synKO mice injected with human AD-tau–enriched extracts. (Q–T) Quantification of p-tau–positive neurons in the ipsilateral hippocampus (Q), contralateral hippocampus (R), ipsilateral entorhinal cortex (S), and contralateral entorhinal cortex (T) of WT and α-synKO mice injected with human AD-tau extract 3, 6, or 9 mpi. A two-tailed t test was performed to calculate the difference between groups; *, P < 0.05; **, P < 0.01. Data are presented as mean ± SEM (n = 5–6 mice per group). All experimental data were verified in at least two independent experiments.