Background: Lithium is used as a stabilizer agent in mood disorders such as bipolar disorder. Studies have been shown that lithium caused memory deficit in patients treated with the drug. Methods: In the present study, using inhibitory avoidance task (step-down model), memory impairment by lithium in male NMRI mice has been investigated. Results: Immediate post-training administration of different doses of lithium (1, 2 and 4 μg/mouse) impaired memory retention 24h later. Injection of the same doses of lithium 30 min after training showed impairing effect on memory more effectively. With injection of lithium 45 min after training its impairing effect was decreased and only at the dose of 4 μg/mouse, memory impairment was observed. Conclusions: The results show that post-training administration of lithium dose-and time-dependently impaired memory of inhibitory avoidance. It can be concluded that lithium impairs memory retention and its effect at 30 min after training was maximum response.
