Effects of Kihi-to on Aβ(25–35)-induced spatial memory deficits. Aβ(25–35) (25 nmol) was injected into the right lateral ventricle of mice. From ten days after the injection, mice were administered vehicle (Veh, water by p.o.; DMSO by i.v., n = 10; squares) or Kihi-to (100 mg/kg B.W., p.o., n = 9; triangles) for 3 days. The control mice (Cont, n = 8; circles) were injected with a reverse peptide, Aβ(35–25), and then administered vehicle. After that, memory acquisition tests were continued for 5 days in a Morris water maze (A). Escape latencies to a hidden platform were measured. Three days after the last trial of the memory acquisition test, the memory retention test was performed (C). The number of crossings over the position at which the platform had been located was measured for 60 s. Swimming velocities of mice in the memory acquisition test (B) and the retention test (D) are shown. *p < 0.05 vs. Veh. (a: Repeated measures two-way ANOVA followed by Holm-Sidak post hoc test, c: one-way ANOVA followed by Holm-Sidak post hoc test).