The effect of intracerebroventricular (i.c.v.) injections of L-arginine, a nitric oxide (NO) precursor and L-NAME, an inhibitor of NO synthase, on retrieval of state-dependent memory induced by LiCl (lithium) was investigated. A one-trial step-down inhibitory avoidance task was used for memory assessment in adult male NMRI mice. Intraperitoneal administration of lithium (10 mg/kg), immediately after training, impaired memory on the test day. Pretest administration of different doses of lithium (5, 10 and 20 mg/kg) reversed the impairment of memory caused by posttraining lithium (10 mg/kg). In addition, pretest administration of L-arginine (0.001, 0.01 and 0.1 lg/mouse, i.c.v.) or L-NAME (0.001, 0.01 and 0.1 lg/mouse, i.c.v.) also reversed amnesia induced by posttraining lithium. Furthermore, pretest coadministration with lithium of a dose of L-arginine (0.0001 lg/mouse, i.c.v.) or L-NAME (0.0001 lg/mouse, i.c.v.) that had no effects when administered alone, increased the effect of lithium on retrieval of inhibitory avoidance memory. The results suggest that NO may have a modulatory role on state-dependent retrieval of inhibitory avoidance memory induced by lithium.
