Figure 1.

Dose response of acute ketamine challenge in stressed mice. Chronic restraint stress produced depressive-like behaviors in CD-1 mice, as assessed by increased immobility time in the forced swim test (FST) and tail-suspension test (TST) (a). In stressed mice, acute injection of ketamine at a dose of 50mg/kg not only significantly suppressed immobility in both tests (b), but also increased locomotor activity measured by the open-field test (OFT) (c). Data are mean±SEM (n =6–8). +P<.05, t test; *P<.05, **P<.01, compared with control groups, according to Student–Newman–Keuls multiple comparison test after a 1-way analysis of variance (ANOVA).