Impact of Dopamine D۱ Receptors of the Dorsal Hippocampus on Improving Effect of Nicotine in Ethanol-Induced Amnesia

Background and Objective: Ethanol and nicotine increase dopamine release in different parts of the brain such as the nucleus accumbens and the hippocampus. Dopamine D۱ receptors have been detected in dorsal hippocampus known as a key brain region that seems to mediate some behavioral effect of ethanol and nicotine. The present study was carried out to determine the influence of dopamine D۱ receptors of dorsal hippocampus as to the effect of Nicotine on ethanol-induced amnesia. Materials and Methods: In this experimental study, ۱۹۲ adult male NMRI mice were anaesthetized and cannulae implanted bilaterally in the CA۱ regions of the dorsal hippocampus using stereotaxic method. Seven days after recovery from surgery, the behavioral testing was started using inhibitory avoidance task. In this study, ethanol, nicotine and SCH۲۳۳۹۰ (D۱ receptor antagonist) were used. Results: Pre-training or pre-test injection of ethanol induced amnesia (P<۰.۰۰۱). The amnesia induced by pre-training ethanol restored with pre-test administration of same doses of ethanol (P<۰.۰۰۱). Pre-test injection of nicotine restored amnesia induced by pre-training ethanol (P<۰.۰۰۱). Pre-test intra-CA۱ injection of SCH۲۳۳۹۰ by itself impaired memory and prevented the nicotine reversal effect on ethanol- induced memory impairment (P<۰.۰۰۱). Conclusion: These results suggest that dopamine D۱ receptor of dorsal hippocampus may play an important role in improving effect of nicotine on the ethanol-induced amnesia.

کلیدواژه ها:

Keywords: Ethanol ، Nicotine ، Dorsal hippocampus ، Dopamine D۱ receptor ، State dependent learning