Long-Lasting Antidepressant Action of Ketamine, but Not Glycogen Synthase Kinase-3 Inhibitor SB216763, in the Chronic Mild Stress Model of Mice

Summary

A single dose of the NMDA receptor antagonist ketamine, but not the GSK-3 inhibitor SB216763, produced long-lasting antidepressant effects in a mouse model of chronic mild stress (CMS). In CMS mice, ketamine reversed the drop in sucrose intake and reduced immobility in the tail suspension and forced swimming tests, effects that persisted for 8 days after a single dose. The GSK-3 inhibitor did not produce these effects. Ketamine also reduced immobility in non-stressed control mice. These results suggest that ketamine's rapid and sustained antidepressant action may not depend on GSK-3 inhibition.

Study at a glance

Abstract

BACKGROUND: Clinical studies demonstrate that the N-methyl-D-aspartate (NMDA) receptor antagonist, ketamine, induces rapid antidepressant effects in patients with refractive major depressive disorder and bipolar depression. This rapid onset of action makes ketamine a highly attractive drug for patients, particularly those who do not typically respond to therapy. A recent study suggested that glycogen synthase kinase (GSK)-3 may underlie the rapid antidepressant action of ketamine, although the precise mechanisms are unclear. In this study, we examined the effects of ketamine and GSK-3 inhibitor SB216763 in the unpredictable, chronic mild stress (CMS) mouse model of mice. METHODOLOGY/PRINCIPAL FINDINGS: Adult C57/B6 male mice were divided into 2 groups, a non-stressed control group and the unpredictable CMS (35 days) group. Then, either vehicle, ketamine (10 mg/kg), or the established GSK-3 inhibitor, SB216763 (10 mg/kg), were administered into mice in the CMS group, while vehicle was administered to controls. In the open field test, there was no difference between the four groups (control+vehicle, CMS+vehicle, CMS+ketamine, CMS+SB216763). In the sucrose intake test, a 1% sucrose intake drop, seen in CMS mice, was significantly attenuated after a single dose of ketamine, but not SB216763. In the tail suspension test (TST) and forced swimming test (FST), the increased immobility time seen in CMS mice was significantly attenuated by a single dose of ketamine, but not SB216763. Interestingly, the ketamine-induced increase in the sucrose intake test persisted for 8 days after a single dose of ketamine. Furthermore, a single administration of ketamine, but not SB216763, significantly attenuated the immobility time of the TST and FST in the control (non-stressed) mice. CONCLUSIONS/SIGNIFICANCE: These findings suggest that a single administration of ketamine, but not GSK-3 inhibitor SB216763, produces a long-lasting antidepressant action in CMS model mice.