Fig. 2. Crossing over drug groups in repeated forced swims yields antidepressant-like effects.

Shown are the four FSTs from Experiment 2, where a gap of 7 or 14 days was used for shorter versus longer washout periods, respectively, between swims. After FST1, the vehicle and 0.02 mg/kg dose groups were switched (crossed over), as were the 0.2 and 2.0 mg/kg groups, for FST2. Such crossing over was also carried out in the subsequent FSTs, where maroon color indicates the original drug grouping, and green indicates the crossed over grouping. As shown, the maroon grouping (FST1 = FST3) was not significantly antidepressant-like to donepezil, whereas the green grouping (FST2 = FST4) was during FST2 (and also in FST4 based on the u-shaped randomization test). Error bars represent mean ± SEM. For bars: *adjusted p < 0.05 versus vehicle, **adjusted p < 0.01 versus vehicle (or adjusted p value is explicitly shown for a statistical trend). *p < 0.05 for u-shape, **p < 0.01 for inverted u-shape.