Figure 2.

Preketamine treatment with a subtherapeutic dose of lithium potentiates a low dose of ketamine-induced antidepressant-like effects. In CD-1 mice, long-term treatment with a sub- (600mg/L) or low therapeutic dose (1200mg/L) of lithium chloride in drinking water for 3 weeks did not affect body weight (a) or locomotor activity (b). Pretreatment with 600mg/L of lithium alone had no effect on immobility time in saline-challenged stressed mice (lithium alone group), but significantly potentiated the response induced by a very low dose of ketamine (2.5mg/kg) in the forced swim test (FST) (lithium + ketamine group) (c). The locomotor activity of stressed mice measured by the open-field test (OFT) was not affected by any given treatment (d). Data are mean±SEM (n =6–12). *P<.05, **P<.01, according to Student–Newman–Keuls multiple comparison test after a 1-way analysis of variance (ANOVA).