Tau ablation, γ-secretase modulation, and NMDAR blockade each ameliorates deficits in anterograde axonal transport of mitochondria in Aβ-producing primary hippocampal neurons from hAPP-J20 mice. (A and B) Anterograde (A) and retrograde (B) axonal transport in neurons from mice of the indicated genotypes. n = 25–51 axons from three to five mice and three to six independent sessions for each genotype at DIV 10–14. ***, P < 0.001 versus Tau^+/+ or as indicated by bracket (Dunnett’s test). (C) Levels of Aβ_1-x and Aβ_1–42 in the medium, measured by ELISA, were roughly equivalent to 4 and 0.55 nM of Aβ monomer, respectively. n = 4–9 wells from three to five mice per genotype at DIV 14. (D) Aβ levels in DIV 14 medium from hAPP/Tau^+/+ neurons treated with a GSM (BMS-893204; 100 nM final concentration) from DIV 1–14, relative to Aβ levels in replicate cultures treated with vehicle (DMSO; 0.001% final concentration). n = 5–6 wells from four mice per treatment. ***, P < 0.001 versus vehicle (arbitrarily defined as 1.0) by one-sample t test. (E) Axonal transport in neurons of the indicated genotypes treated with GSM (100 nM) or vehicle (Veh; DMSO) over 12–14 d. n = 23–29 axons from three mice per genotype and treatment from three independent sessions at DIV 12–14. ***, P < 0.001 (Dunnett’s test). (F) Axonal transport in neurons of the indicated genotypes before (baseline) and after treatment with the selective NMDAR antagonist D-AP5 (100 µM final concentration; for 1 h) at DIV 12–14. n = 22–24 axons from three mice for each genotype at DIV 12–14. **, P < 0.01 versus Tau^+/+ baseline (Dunnett’s test); ###, P < 0.001 (paired t test, Bonferroni). Data are means ± SEM.