FIGURE 2.
ECH treatment improves spatial learning and memory in 10-month-old 2 × Tg-AD mice in the Morris water maze test. (A) In the place navigation test, the vehicle-treated 2 × Tg-AD mice showed significantly longer escape latencies compared with vehicle-treated Non-Tg mice (##P < 0.01, ###P < 0.001, vehicle-treated 2 × Tg-AD mice vs. vehicle-treated Non-Tg mice), and ECH treatment reduced escape latency in 2 × Tg-AD mice remarkably (*P < 0.05, **P < 0.01, and ***P < 0.001, ECH-treated 2 × Tg-AD mice vs. vehicle-treated 2 × Tg-AD mice). (B) No significant differences were detected in the average swimming speed among the 4 groups during the place navigation test (P = 0.516). During the spatial probe test, (C) the number of crossings of the area of the removed platform and (D) time spent in the target vs. opposite quadrant were recorded; vehicle-treated 2 × Tg-AD mice showed significantly inferior performance than ECH-treated 2 × Tg-AD mice and vehicle- and ECH-treated Non-Tg mice. (E) Representative images of the route of travel during the spatial probe test were recorded. No significant differences were detected in (F) the escape latency (P = 0.379) or (G) the average swimming speed (P = 0.725) among the 4 experimental groups during the visible-platform test. All data are presented as the mean ± SEM (n = 18 mice per group). Non-Tg, non-transgenic littermates; 2 × Tg-AD, APPswe/PS1dE9 mice; Veh, vehicle (normal saline); ECH, echinacoside; NS, no significant difference.