Interactions between the Cannabinoid and Nicotinic Systems in Inhibitory Avoidance Learning in Mice

Cannabinoid exerts have widespread and complex effects on higher cognitive functions. An overlapping distribution of nicotinic receptors with cannabinoid receptors has been reported in some brain structures such as dorsal hippocampus, thus the functional interactions between cannabinoid and nicotinic systems in cognitive control seems possible. In the present study, the effects of mecamylamine on WIN55, 212-2 induced state-dependent learning was examined. In this experimental study, 280 adult male NMRI mice were esthetized and, then, were cannulae implanted bilaterally in the CA1 regions of the dorsal hippocampus using stereotaxic method. Seven days after the recovery from surgery, behavioral testing was started in inhibitory avoidance task. The animals were trained in a step- down type inhibitory avoidance task and tested 24h after training to measure the step- down latency for the assessment of memory retention. All experiments were conducted in accordance with "standard ethical guidelines for animal care and use". Post-training administration of WIN55, 212-2 and AM251 decreased the memory retrieval. The memory impairment induced by WIN55, 212-2 was completely reversed by pre-test administration of WIN55, 212-2 and/or mecamylamine, suggesting WIN55, 212-2 induced state-dependent memory. These results suggest that nicotinic receptors of the dorsal hippocampal may play an important role in Win55,212-2-induced amnesia and WIN55,212-2 state-dependent memory.