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

ABSTRACT

Beta-carbolines alkaloids such 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. 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. 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 micro g/mice] also induced amnesia. On the other hand, pre-test intra-CA1 injection of ineffective doses of mecamylamine [0.5, 1 and 2 micro g/mice] fully restored harmane induced amnesia. The present finding in this study indicated that a complex interaction exists between nicotinic receptor of dorsal hippocampus and amnesia induced by Harmane