Morris water maze test. (A). Visible platform training. There was no significant group difference in average swim velocity or escape latency to the platform (B). Hidden platform training. aCSF-vehicle, aCSF-DT and LPS-DT groups improved their daily performance during the acquisition phase of the Morris water maze task, whereas LPS-vehicle rats showed an impaired learning profile. The average escape latency of LPS-vehicle rats was significantly higher than that of aCSF-vehicle animals on the second (*p < 0.05) and third day (***p < 0.001). The average escape latency of LPS-DT rats did not significantly differ from aCSF-vehicle rats, and was significantly lower than that of LPS-vehicle animals on the third day of training (##
p < 0.01). (C). Probe test. aCSF-vehicle, aCSF-DT and LPS-DT groups spent a significantly higher percentage of time in the target quadrant than the other quadrants (***p < 0.001 vs. other quadrants) whereas LPS-vehicle rats did not.