Journal of Rafsanjan University of Medical Sciences

  Interaction of Intrahippocampal Injection of Naltheroxone and Corticosterone on Consolidation and Retreival Memory Processes in Passive

  Avoidance Task in Rat

  AA. Vafaei [1] , A. Rashidy-Pour [2]

  Received: 15/01/08 Sent for Revision: 01/07/08 Received Revised Manuscript: 15/09/08 Accepted: 20/10/08

  Background and Objectives Previous studies suggested that the role of corticosterone on memory process probably is mediated by opiate system in Dorsal Hippocampus (DH). The aim of this study was to test whether there is any interaction between glucocorticoids and opiate system on memory consolidtaion and retrieval in passive avoidance learning task.

  Material and Methods: In this experimental study 120 male Wistar rats (250–300 gr) surgically implanted bilaterally with cannulae aimed at the DH were trained in passive anoidnace learning (PAL) task. Two days after training, retention test was done. Naltoroxe (10 or 20 µ g/ul/ perside) were injected bilaterally into DH following immediately after training by IP injection of corticostrone (1 mg/kg) or 30 min before of IP injection of corticostrone (1 mg/kg) in retrieval test.

  Results: The data indicated that injection of corticostrone immediatly after training of injected 30 min before of retrieval test enhanced and impaired memory consolidation and retrieval respectively (p<0.01) and these effects were blocked by injection of nalthroxone on DH (p<0.01).

  Conclusion: The findings showed that the opioid receptors in hippocampus paly an important role in mediating the enhancing or impairing effects of corticosterone on memory consolidation and retrieval in passive avoidance task.

  Key words: Hippocampus, Consolidation and Retrieval memory, Nalthroxone, Corticosterone, Rat

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

  Conflict of interest: None declared.

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