Research Paper: The Modulatory Role of Orexin 1 Receptor in CA1 on Orofacial Pain-induced Learning and Memory Deficits in Rats

• Main Authors: Razieh Kooshki, Mehdi Abbasnejad, Saeed Esmaeili-Mahani, Maryam Raoof
• Format: Article
• Language: English
• Published: Iran University of Medical Sciences 2017-05-01
• Series: Basic and Clinical Neuroscience
• Subjects: Orofacial pain; Orexin 1 Receptor; CA1; Learning and memory; Capsaicin
• Online Access: http://bcn.iums.ac.ir/browse.php?a_code=A-10-906-1&slc_lang=en&sid=1
• ISSN: 2008-126X; 2228-7442

Introduction: Cognitive impairment is commonly associated with pain. The modulatory role of orexin 1 receptor (OX1R) in pain pathways as well as learning and memory processes is reported in several studies. The current study was designed to investigate the possible role of CA1-hippocampal OX1R on spatial learning and memory of rats following capsaicin-induced orofacial pain. Methods: Orofacial pain was induced by subcutaneous intra lip injection of capsaicin (100 μg). CA1 administration of orexin A and its selective antagonist (SB-334867-A) were performed 20 minutes prior to capsaicin injection. Learning and spatial memory performances were assessed by Morris Water Maze (MWM) task. Results: Capsaicin treated rats showed impairment in spatial learning and memory. In addition, pretreatment with orexin A (20 and 40 nM/rat) significantly attenuated learning and memory impairment in capsaicin-treated rats. Conversely, blockage of OX1R via SB-334867-A (40 and 80 nM/rat) significantly exaggerated learning and memory loss in capsaicin-treated rats.  Conclusion: The obtained results indicated that CA1 OX1R may be involved in modulation of capsaicin –induced spatial learning and memory impairment.