Figure 5.

Septal urocortin 2 increased anxiety when combined with stress in CRF₂ receptor wild-type mice on a mixed C57BL/6 × 129 background. Effect of septal urocortin 2 (vehicle or 0.48, 4.8, or 48 pmol) in CRF₂ receptor wild-type mice treated with no stress or 30 min of immobilization stress on the following: a, latency to enter the light side of the light–dark box (seconds); b, total time spent in the light side of the light–dark box (seconds); c, locomotion in the open field (total square entries); d, percentage of time in the center of the open field; e, locomotion in the open field with a novel object (total square entries); and f, percentage of time spent in the center with a novel object. Transitions in the light–dark box and percentage of center entries in the open-field and novel-object tests are not shown. Urocortin 2 did not affect anxiety-like behavior in the no-stress condition at any dose tested. In the stress condition, 48 pmol of urocortin 2 increased anxiety-like behavior in the light–dark box and novel-object tests; the 4.8 pmol dose increased anxiety in the novel-object test in the stress condition but not the no-stress condition. Data are presented as mean ± SEM. ***p < 0.001.