CD-1 and Balb/cJ mice do not show enduring antidepressant-like effects of ketamine in tests of acute antidepressant efficacy.

Abstract

In patients, ketamine is a fast-acting antidepressant that can induce long-lasting symptom relief. Similar rapid effects have been reported in rodents, but reports of lasting effects are limited. We sought to extend past findings by examining dose-response curves that overlap with the individual doses previously reported to induce lasting effects in rodents and determining whether effects generalize to the tail suspension test (TST) and Balb/cJ mice. Using common tests of antidepressant efficacy we first confirmed our ability to detect the effects of desipramine, a well-characterized antidepressant drug. Next, we sought to determine whether two non-competitive NMDA antagonists, ketamine and MK-801, had long-lasting antidepressant-like effects in CD-1 mice, a strain that has often been used to demonstrate the short-term antidepressant-like effects of ketamine. Finally, we examined the short- and long-term effects of ketamine in a mouse strain that is more sensitive to antidepressant-like effects, Balb/cJ mice. In CD-1 mice, desipramine treatment yielded significant short-term antidepressant-like effects in the TST and the forced swimming test (FST). However, no significant enduring effects of ketamine or MK-801 were observed 1 week later. Short-term effects of ketamine in the TST were observed in Balb/cJ mice, but lasting effects were absent 1 week later. Although the TST and FST have been widely used to detect antidepressant-like effects in mice, they do not appear to be sensitive to long-lasting antidepressant-like effects of ketamine in mice and, therefore, do not model the therapeutic effects of ketamine that have been reported in humans with major depression.