Background: Nitric oxide and mecamylamine have an important role in anxiety-like behavior. Determining the site of action in the brain and interaction between these agents need to be investigated. Therefore, this study aimed to investigate the possible interaction between mecamylamine and nitric oxide in dorsal hippocampus using the elevated plus-maze test of anxiety.

Materials and Methods: This experimental study was performed on 180 male NMRI mice. Mice were anaesthetized with ketamine and xylazine and two cannuale were inserted stereotaxically into the CA1 region of the dorsal hippocampus. All animals were allowed to recover for 1 week before the beginning of the behavioral testing. The elevated plus-maze was used to test the anxiety-like behavior.

Results: Bilateral intra-dorsal hippocampal injections of mecamylamine, L-arginine or L-NAME induced the anxiogenic effects. Intra-dorsal hippocampal injection of ineffective dose of mecamylamine before different doses of L-arginine or L-NAME potentiated the anxiogenic effects of L-arginine or L-NAME.

Conclusion: Results reveal that both nitric oxide and mecamylamine not only play a part in the modulation of anxiety in the dorsal hippocampus of mouse but also have demonstrated a complex interaction as well.