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

  M. Piri [1] , M. Nasehi [2] , M.R. Zarrindast [3]

  Received: 09/07/09 Sent for Revision: 16/03/10 Received Revised Manuscript: 13/04/10 Accepted: 24/04/10

  Background and Objective: 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.

  Materials and Methods: In this experimental study, 280 adult male NMRI mice were anaesthetized 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".

  Results: 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.

  Conclusion: 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.

  Key words: WIN55, 212-2, Mecamylamine, Inhibitory avoidance learning, Mice

  Funding: This research was funded by Tehran University of Medical Sciences.

  Conflict interest: None declared.

  Ethical approval: The Ethics Committee of Tehran University of Medical Sciences approved the study.

  [1] - Instructor, Dept. of Biology, Islamic Azad University, Ardabil branch, Ardabil, Iran

  (Corresponding Author) Tel: (0451) 7727905, Fax: (0451) 7729826, E-mail: biopiri@yahoo.com.

  [2] - Assistant Prof., Dept. of Biology, Islamic Azad University, Garmsar branch, Semnan, Iran

  [3] - Prof., Dept. of Pharmacology and Iranian National Center for Addiction Studies, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran