The interaction of nicotine and dopamine D1 receptors of the dorsal hippocampus in the perforated plate anxiety test

    Background: Nicotinic and dopaminergic systems influence anxiety behavior. Furthermore, the interaction between nicotine and dopamine D1 receptors has been demonstrated in modulation of some behaviors.   Objective: To investigate the involvement of dorsal hippocampus dopaminergic D1 receptor in the nicotine effects on anxiety behavior.   Methods: This was an experimental study carried out at Tehran Institute of Cognitive Sciences in 2009. Initially, 190 mice in 10-member groups were placed in a stereotaxic apparatus and two cannulae placed in the CA1 region of hippocampus. Later, the effects of dopaminergic D1 receptors agonist (SKF38393) and antagonist (SCH23390) on nicotine anxiogenic effects in mice were measured using hole-board test of anxiety. Data were analyzed using one-way analysis of variance followed by Dunnett’s test.   Findings: Nicotine (0.5 mg/kg) produced anxiogenic effect (P<0.001). Intra-CA1 injections of ineffective doses of SCH23390 reversed the anxiogenic effects induced by nicotine (P<0.001). Furthermore, co-administration of ineffective dose of SKF38393 plus ineffective dose of nicotine increased the anxiogenic effect of nicotine (P<0.001). Locomotion activity was unchanged when no drug was administered.   Conclusion: The results indicated that dopamine D1 receptors of the dorsal hippocampus have modulatory role in the anxiogenic response induced by nicotine.