ABSTRACT
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 in2009. Initially, 190 mice in 10-member groups were placed in a stereotaxic apparatus and twocannulae 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
ABSTRACT
Background and Objective: a number of beta-carboline alkaloids such as harmane are naturally present in the human food chain. In the present study the involvement of dopaminergic system on harmane induced amnesia was investigated
Materials and Methods: one-trial step-down paradigm was used for the assessment of memory retention in adult male NMRI mice
Results: intraperitoneal [i.p.] administration of harmane [5 and 10 mg/kg] immediately after training, dose dependently decreased memory formation. Administration of D1/D2 receptors agonist, Apo morphine [0.5 and 1 mg/kg, i.p.] before testing by itself could not alter memory retrieval. On the other hand, in the animals in which memory formation was impaired due to harmane post-training administration, pre-test administration of Apo morphine [0.5 and 1 mg/kg, i.p.] 24 hrs. After training in days test restored memory Furthermore, administration of SCH23390 [0.025, 0.05 and 0.1 mg/kg, i.p.] or sulpiride [12.5, 25 and 50 mg/kg, i.p.] before testing by itself could not alter memory retrieval, respectively. On the other hand in the animals in which memory formation was impaired due to harmane post-training injection, pre-test administration of SCH23390 [0.05 and 0.1 mg/kg] or sulpiride [25, 50 mg/kg, i.p.] 24 hrs. after training in days test decreased harmane-induced amnesia
Conclusion: these findings indicate the involvement of D1/D2 receptors in harmane induced-amnesia through different mechanism[s]