title: The role of trigeminal nucleus caudalis orexin 1 receptor in orofacial pain-induced anxiety in rat.
abstract: The relationship between anxiety and pain has received special attention. Orexins (A and B) are hypothalamic neuropeptides that have diverse functions in the regulation of different physiological and behavioral responses. This study was designed to evaluate the role of orexin 1 receptors (OX1R) within trigeminal nucleus caudalis (TNC) in anxiety following the induction of orofacial pain. The subcutaneous injection of capsaicin (CAP) into the rat upper lip region produced pain responses. OX1R agonist (orexin A) and antagonist (SB-334867) were microinjected into the TNC before the administration of CAP. Anxiety behaviors were investigated using elevated plus maze (EPM) and open-field tests. The results showed that CAP injection significantly decreases the percentage of time spent in the open arms of the EPM and the time spent in the center of the open field. Surprisingly, orexin (50, 100, and 150 pM/rat) significantly exaggerated the CAP effects, whereas SB-334867 (20, 40 nM/rat) significantly inhibited the CAP-induced anxiety. The CAP-injected group showed a significant decrease in the percentage of entries to open arms in the EPM and the number of visits in the center area of the open field compared with the control group. Orexin significantly potentiated the mentioned effects of CAP, whereas SB-334867 (40, 80 nM/rat) exerted a significant inhibitory effect on CAP-induced anxiety. The overall results indicated that the TNC OX1Rs play an important role in orofacial pain-induced anxiety.
authors: aDepartment of Biology, Shiraz Branch bDepartment of Biology, Science and Research Branch, Islamic Azad University, Shiraz cDepartment of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman dNeuroscience Research Center, Institute of Neuropharmacology eDepartment of Endodontics, School of Dentistry, Kerman University of Medical Sciences, Kerman, Iran.
authors: Mehri
authors: M
authors: Bahaaddini
authors: Saeed
authors: S
authors: Khatamsaz
authors: Saeed
authors: S
authors: Esmaeili-Mahani
authors: Mehdi
authors: M
authors: Abbasnejad
authors: Maryam
authors: M
authors: Raoof
mesh_terms: D000818:Animals; D001007:Anxiety / Q000209:etiology* / Q000473:pathology*; D001583:Benzoxazoles / Q000627:therapeutic use; D002211:Capsaicin / Q000633:toxicity; D004195:Disease Models, Animal; D005106:Exploratory Behavior / Q000187:drug effects; D005157:Facial Pain / Q000139:chemically induced / Q000150:complications* / Q000188:drug therapy; D005557:Formaldehyde / Q000633:toxicity; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008845:Microinjections; D009287:Naphthyridines; D000068796:Orexin Receptor Antagonists / Q000627:therapeutic use; D064446:Orexin Receptors / Q000378:metabolism*; D000068797:Orexins / Q000627:therapeutic use; D010147:Pain Measurement / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014278:Trigeminal Nuclei / Q000378:metabolism*; D014508:Urea / Q000031:analogs & derivatives / Q000627:therapeutic use
chemical_list: C420062:1-(2-methylbenzoxazol-6-yl)-3-(1,5)naphthyridin-4-yl urea; D001583:Benzoxazoles; D009287:Naphthyridines; D000068796:Orexin Receptor Antagonists; D064446:Orexin Receptors; D000068797:Orexins; D005557:Formaldehyde; D014508:Urea; D002211:Capsaicin