Figure 2.

Six hours a day of unpredictable restraint stress (URS) for 10 days increases anxiety-like behavior, enhances contextual fear conditioning, and reduces volume of the entire hippocampus, including dentate gyrus and dorsal and ventral regions of area CA1. A) Timeline showing experimental paradigm. B,C) Stressed rats displayed increased anxiety-like behavior in the elevated plus-maze (B) and novelty-suppressed feeding (C) tests. D) None of the groups showed a preference for the displaced object. E,F) Stress enhanced freezing in a contextual fear conditioning test without affecting extinction (E), but stressed rats later showed greater spontaneous reinstatement of freezing (F). G-J) A month after SPS, hippocampal volume was reduced in the hippocampus as a whole (G) and in the dentate gyrus (H) and throughout the CA1 region (J). Loss of neurogenesis decreased volume in the dentate gyrus and hippocampus as a whole, but neither stress nor inhibition of neurogenesis affected CA3 volume (I). * p < .05 compared to control.