title: A novel operant-based behavioral assay of mechanical allodynia in the orofacial region of rats.
abstract: BACKGROUND
  Detecting behaviors related to orofacial pain in rodent models often relies on subjective investigator grades or methods that place the animal in a stressful environment. In this study, an operant-based behavioral assay is presented for the assessment of orofacial tactile sensitivity in the rat.
  
  
  METHODS
  In the testing chamber, rats are provided access to a sweetened condensed milk bottle; however, a 360° array of stainless steel wire loops impedes access. To receive the reward, an animal must engage the wires across the orofacial region. Contact with the bottle triggers a motor, requiring the animal to accept increasing pressure on the face during the test. To evaluate this approach, tolerated bottle distance was measured for 10 hairless Sprague Dawley rats at baseline and 30 min after application of capsaicin cream (0.1%) to the face. The experiment was repeated to evaluate the ability of morphine to reverse this effect.
  
  
  RESULTS
  The application of capsaicin cream reduced tolerated bottle distance measures relative to baseline (p<0.05). As long as morphine did not cause reduced participation due to sedation, subcutaneous morphine dosing reduced the effects of capsaicin (p<0.001). Comparison with existing method: For behavioral tests, experimenters often make subjective decisions of an animal's response. Operant methods can reduce these effects by measuring an animal's selection in a reward-conflict decision. Herein, a method to measure orofacial sensitivity is presented using an operant system.
  
  
  CONCLUSIONS
  This operant device allows for consistent measurement of heightened tactile sensitivity in the orofacial regions of the rat.
authors.affiliation: J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Drive Biomedical Sciences Building, JG56, Gainesville, FL, 32610, United States. Electronic address: Rohrs.eric@ufl.edu.
authors.forename: Eric L
authors.initials: EL
authors.lastname: Rohrs
authors.affiliation: J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Drive Biomedical Sciences Building, JG56, Gainesville, FL, 32610, United States. Electronic address: hkloefkorn@ufl.edu.
authors.forename: Heidi E
authors.initials: HE
authors.lastname: Kloefkorn
authors.affiliation: J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Drive Biomedical Sciences Building, JG56, Gainesville, FL, 32610, United States; Institute for Cell Engineering and Regenerative Medicine, University of Florida, Gainesville, FL, United States. Electronic address: elakes@ufl.edu.
authors.forename: Emily H
authors.initials: EH
authors.lastname: Lakes
authors.affiliation: J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Drive Biomedical Sciences Building, JG56, Gainesville, FL, 32610, United States. Electronic address: starjacobs@ufl.edu.
authors.forename: Brittany Y
authors.initials: BY
authors.lastname: Jacobs
authors.affiliation: Department of Orthodontics, University of Florida, Gainesville, FL, United States; Pain Research and Intervention Center of Excellence, University of Florida, Gainesville, FL, United States. Electronic address: jneubert@dental.ufl.edu.
authors.forename: John K
authors.initials: JK
authors.lastname: Neubert
authors.affiliation: Department of Oral and Maxillofacial Surgery, University of Florida, Gainesville, FL, United States; Pain Research and Intervention Center of Excellence, University of Florida, Gainesville, FL, United States. Electronic address: caudle@ufl.edu.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Caudle
authors.affiliation: J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Drive Biomedical Sciences Building, JG56, Gainesville, FL, 32610, United States; Pain Research and Intervention Center of Excellence, University of Florida, Gainesville, FL, United States; Institute for Cell Engineering and Regenerative Medicine, University of Florida, Gainesville, FL, United States; Nanoscience Institute for Medical and Engineering Technology, University of Florida, Gainesville, FL, United States. Electronic address: kyle.allen@bme.ufl.edu.
authors.forename: Kyle D
authors.initials: KD
authors.lastname: Allen
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D002211:Capsaicin; D003216:Conditioning, Operant; D004867:Equipment Design; D005157:Facial Pain / Q000175:diagnosis / Q000188:drug therapy; D005260:Female; D006930:Hyperalgesia / Q000175:diagnosis / Q000188:drug therapy; D009020:Morphine / Q000494:pharmacology; D010147:Pain Measurement / Q000295:instrumentation* / Q000379:methods*; D011312:Pressure; D017207:Rats, Sprague-Dawley; D014110:Touch
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine; D002211:Capsaicin
keywords: Allodynia; Behavior; Operant; Orofacial; Pain
references.citation: Pain. 2000 Feb;84(2-3):141-9
references.pmid: 10666518
references.citation: J Neurosci. 1994 May;14(5 Pt 1):2708-23
references.pmid: 8182437
references.citation: Mol Pain. 2010;6:49
references.pmid: 20796319
references.citation: J Mol Neurosci. 2010 Oct;42(2):200-9
references.pmid: 20349343
references.citation: J Neurosci Methods. 2000 Apr 1;97(1):19-29
references.pmid: 10771071
references.citation: J Orofac Pain. 2009 Summer;23(3):253-64
references.pmid: 19639105
references.citation: Brain Res Bull. 1986 Sep;17(3):439-43
references.pmid: 3768747
references.citation: J Neurosci Methods. 2009 Mar 15;177(2):420-6
references.pmid: 19041344
references.citation: Pharmacol Biochem Behav. 2003 Apr;75(1):181-9
references.pmid: 12759126
references.citation: Behav Brain Res. 2011 Mar 1;217(2):477-80
references.pmid: 20974188
references.citation: J Am Dent Assoc. 1993 Oct;124(10):115-21
references.pmid: 8409001
references.citation: Pain. 1996 Sep;67(1):179-88
references.pmid: 8895246
references.citation: J Neurosci Methods. 2010 Mar 30;187(2):207-15
references.pmid: 20096303
references.citation: Mol Pain. 2008;4:59
references.pmid: 19019214
references.citation: Annu Rev Neurosci. 2001;24:487-517
references.pmid: 11283319
references.citation: Brain Res. 1981 Jun 29;215(1-2):342-8
references.pmid: 7260593
references.citation: Acta Neurol Belg. 2001 Mar;101(1):32-8
references.pmid: 11379273
references.citation: Pain. 2009 Mar;142(1-2):133-41
references.pmid: 19167818
references.citation: J Neurosci Methods. 2011 Sep 30;201(1):46-54
references.pmid: 21782847
references.citation: Anesthesiology. 2004 Aug;101(2):476-87
references.pmid: 15277932
references.citation: Neurosci Biobehav Rev. 2000 May;24(3):375-89
references.pmid: 10781697
references.citation: J Neurosci Methods. 1982 Sep;6(3):245-52
references.pmid: 7144237
references.citation: Prog Neuropsychopharmacol Biol Psychiatry. 2012 Aug 7;38(2):149-58
references.pmid: 22449477
references.citation: Pain. 2009 Aug;144(3):270-7
references.pmid: 19464796
references.citation: Behav Brain Res. 2006 Jun 30;170(2):308-15
references.pmid: 16675039
references.citation: Pain. 1989 Jul;38(1):99-107
references.pmid: 2780068
references.citation: Comp Med. 2002 Feb;52(1):44-9
references.pmid: 11900412
references.citation: Physiol Behav. 1978 Aug;21(2):287-90
references.pmid: 693656
references.citation: Pain. 2005 Aug;116(3):386-95
references.pmid: 15982812
references.citation: J Neurophysiol. 1991 Jul;66(1):190-211
references.pmid: 1919666
references.citation: Pain. 2002 Mar;96(1-2):81-7
references.pmid: 11932064
references.citation: Pain. 1988 Apr;33(1):87-107
references.pmid: 2837713
references.citation: Pain. 1995 Nov;63(2):163-72
references.pmid: 8628581
references.citation: Spine (Phila Pa 1976). 2005 Aug 15;30(16):1821-7
references.pmid: 16103850
references.citation: Brain Res. 2007 Dec 12;1184:141-8
references.pmid: 17980861
references.citation: Pain. 1997 Aug;72(1-2):269-75
references.pmid: 9272812
references.citation: Psychopharmacology (Berl). 1980;72(1):103-6
references.pmid: 6780999
references.citation: J Dent Res. 2012 Sep;91(9):883-7
references.pmid: 22797321
references.citation: Brain Behav. 2012 Sep;2(5):678-97
references.pmid: 23139912
references.citation: Neuroscience. 2011 Sep 8;190:379-85
references.pmid: 21664434
references.citation: Nature. 1997 Oct 23;389(6653):816-24
references.pmid: 9349813
references.citation: Exp Brain Res. 1997 Aug;116(1):97-103
references.pmid: 9305818
references.citation: Pain. 1991 Dec;47(3):285-94
references.pmid: 1784499
references.citation: Pain. 1999 Feb;79(2-3):113-9
references.pmid: 10068156
references.citation: Neurosci Biobehav Rev. 2002 Dec;26(8):907-23
references.pmid: 12667496