Effects of mecamylamine (a nicotinic receptor antagonist) on harman induced-amnesia in an inhibitory avoidance test

  Introduction: β-carbolines alkaloids suchv as harmane have been found in common plant-derived foodstuffs (wheat, rice, corn, barley, grape and mushrooms). These alkaloids have many cognitive effects including alteration short and long term memory. In the present study, the effect of intra-CA1 injection of the nicotinic receptor antagonist mecamylamine on amnesia induced by harmane was examined in mice.   Materials and Methods: Mice were bilaterally implanted with chronic cannulae in the CA1 regions of the dorsal hippocampus. One week after cannulae implantation, mice were trained in a step-down type inhibitory avoidance task, and were tested 24 h after training to measure step-down latency as a scale of memory.   Results: Pre-training or post-training systemic injection of harmane induced amnesia. Pre-testing intra-dorsal hippocampus administration of the high dose of nicotinic receptor antagonist, mecamylamine (4 µg/mice) also induced amnesia. On the other hand, pre-test intra-CA1 injection of ineffective doses of mecamylamine (0.5, 1 and 2 µg/mice) fully restored harmane induced amnesia.   Conclusion: The present finding in this study indicated that a complex interaction exists between nicotinic receptor of dorsal hippocampus and amnesia induced by Harmane.