title: Changes in hippocampal orexin 1 receptor expression involved in tooth pain-induced learning and memory impairment in rats.
abstract: Orexin 1 receptor signaling plays a significant role in pain as well as learning and memory processes. This study was conducted to assess the changes in orexin 1 receptor expression levels in hippocampus following learning and memory impairment induced by tooth inflammatory pulpal pain. Adult male Wistar rats received intradental injection of 100 µg capsaicin to induce pulpal pain. After recording the pain scores, spatial learning and memory were assessed using Morris Water Maze test. The hippocampal levels of orexin 1 receptor mRNA and protein were determined by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) and immunoblotting respectively. The data showed that capsaicin-induced tooth inflammatory pulpal pain was correlated with learning and memory impairment. Intra-hippocampal injection of orexin A inhibited pain-induced learning and memory impairment. However, orexin 1 receptor antagonist, SB-334867, had no effect on learning and memory impairment. Moreover, capsaicin-induced pain significantly decreased hippocampal orexin 1 receptor mRNA and protein levels. Meanwhile, reversed changes took place in the ibuprofen-pretreated group (p < 0.05). It seems that decrease in orexin 1 receptor density and signaling could be involved in tooth pain-induced learning and memory impairment.
authors.affiliation: Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran; Laboratory of Molecular Neuroscience, Neuroscience Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Ramin
authors.initials: R
authors.lastname: Raoof
authors.affiliation: Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Esmaeili-Mahani
authors.affiliation: Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Abbasnejad
authors.affiliation: Laboratory of Molecular Neuroscience, Neuroscience Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran; Department of Endodontics, School of Dentistry, Kerman University of Medical Sciences, Kerman, Iran. Electronic address: Maryam.raoof@gmail.com.
authors.forename: Maryam
authors.initials: M
authors.lastname: Raoof
authors.affiliation: Laboratory of Molecular Neuroscience, Neuroscience Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Sheibani
authors.affiliation: Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran.
authors.forename: Razieh
authors.initials: R
authors.lastname: Kooshki
authors.affiliation: Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran.
authors.forename: Ladan
authors.initials: L
authors.lastname: Amirkhosravi
authors.affiliation: Department of Motor Behaviour, Facaulty of Physical Education, Tehran University, Tehran, Iran.
authors.forename: Foroozan
authors.initials: F
authors.lastname: Rafie
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D001583:Benzoxazoles / Q000494:pharmacology; D002211:Capsaicin / Q000633:toxicity; D003782:Dental Pulp / Q000187:drug effects; D006624:Hippocampus / Q000378:metabolism / Q000503:physiopathology*; D007052:Ibuprofen / Q000627:therapeutic use; D007180:Incisor; D007859:Learning Disabilities / Q000209:etiology* / Q000235:genetics / Q000503:physiopathology; D008297:Male; D018782:Maze Learning / Q000502:physiology; D008569:Memory Disorders / Q000209:etiology* / Q000235:genetics / Q000503:physiopathology; D009287:Naphthyridines; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D059225:Nociception / Q000187:drug effects; D064446:Orexin Receptors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D000068797:Orexins / Q000494:pharmacology; D010147:Pain Measurement; D012333:RNA, Messenger / Q000096:biosynthesis; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D016037:Single-Blind Method; D014098:Toothache / Q000188:drug therapy / Q000235:genetics / Q000503:physiopathology / Q000523:psychology*; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C420062:1-(2-methylbenzoxazol-6-yl)-3-(1,5)naphthyridin-4-yl urea; D000894:Anti-Inflammatory Agents, Non-Steroidal; D001583:Benzoxazoles; C578627:Hcrtr1 protein, rat; D009287:Naphthyridines; D009419:Nerve Tissue Proteins; D064446:Orexin Receptors; D000068797:Orexins; D012333:RNA, Messenger; D014508:Urea; D002211:Capsaicin; D007052:Ibuprofen
keywords: Capsaicin; Gene expression; Learning and memory; Orexin 1 receptor; Tooth inflammatory pulpal pain