Nitric oxide in the dorsal hippocampal area is involved on muscimol state-dependent memory in the step-down passive avoidance test

摘要

In the present study, the effects of intra-dorsal hippocampal (intra-CA1) injections of nitric oxide (NO) agents on muscimol state-dependent memory were examined in mice. A single-trial step-down passive avoidance task was used for the assessment of memory retrieval in adult male NMR1 mice. Post-training intra-CAl administration of a GABA_A receptor agonist, muscimol (0.05 and 0.1 mug/mouse) dose dependently induced impairment of memory retention. Pre-test injection of muscimol (0.05 and 0.1 mug/mouse) induced state-dependent retrieval of the memory acquired under post-training muscimol (0.1 mug/mouse, intra-CAl ) influence. Pre-test injection of a NO precursor, L-arginine (1 and 2 mug/mouse, intra-CAl) improved memory retention, although the low dose of the drug (0.5 mug/mouse) did not affect memory retention.