P-tau pathology is enhanced under copathology conditions after injection of AD-tau–enriched extracts combined with α-syn mpffs compared with AD-tau extracts alone. (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 mice 3, 6, or 9 mpi of either AD-tau–enriched extracts alone or combined with α-syn mpffs. (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. (P) Semiquantitative heat mapping of p-tau pathology in WT mice injected with either human AD-tau extract alone or combined with α-syn mpffs. (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 mice injected with either human AD-tau–enriched extracts alone or combined with α-syn mpffs 3, 6, or 9 mpi. A two-tailed t test was performed to calculate the difference between groups; *, P < 0.05; **, P < 0.01; ***, P < 0.001. Data are presented as mean ± SEM (n = 5–6 mouse brains per group). Scale bar, 100 µm. All experimental data were verified in at least two independent experiments.