Fig. 1.

Schematic illustration of the protocol of intermittent psychological stress exposure. Communication box has nine compartments (10 cm × 10 cm) divided transparent Plexiglas walls. For the repeated foot stress exposure, 120-times of electrical shock (0.6 mA, 1 s duration) was delivered with every 47 s halt through the grid floor by a shock generator, while for the intermittent stress exposure, 120-times of electrical shock (0.6 mA, 1 s) was randomly delivered by the program of cycler timer, CBX-CT. Details are described under the Material and methods. For the psychological stress, mice were put on the floors covered with plastic plates.