title: Expression of the spinal 5-HT7 receptor and p-ERK pathway in the carrageenan inflammatory pain of rats.
abstract: BACKGROUND
  Although the inhibitory role of the 5-hydroxytrypatmine receptor 7(5-HT7R) on nociceptive processing is generally recognized, an excitatory effect associated with a reduced 5-HT7R expression has also been observed in the nerve injury model. In the carrageenan model, no significant effect is produced by the 5-HT7R activation, but the change in 5-HT7R expression has not been examined. Lesioning of the spinal serotonergic pathway enhances allodynia in the carrageenan model, but it also relieves several other pain states, including in the formalin model. While lesioning suppresses the activation of the extracellular signal-regulated kinase (ERK) of the spinal cord in the formalin model, its role in the carrageenan model has not been reported.
  
  
  METHODS
  Following intraplantar injections of carrageenan, the spinal 5-HT7R expression was examined using Western blotting in male Sprague-Dawley rats. The effect of serotonergic pathway lesioning with intrathecal 5,7-dihydroxytryptamine (5,7-DHT) on the expression of the phospho-ERK was measured.
  
  
  RESULTS
  The expression of the 5-HT7R in the carrageenan model was not significantly different from that of naive animals. The expression of the spinal p-ERK in the carrageenan model was significantly increased, but returned to the level of a naive rat 1 hour after the carrageenan injection. However, it remained significantly higher 1 hour after the injection in the animals treated with 5,7-DHT than in the naive and control rats.
  
  
  CONCLUSIONS
  The expression of the spinal 5-HT7R is not altered by peripheral inflammation with carrageenan, suggesting that the lack of antinociceptive effect of the 5-HT7R activation is partly attributable to the absence of changes in the expression of the 5-HT7R in the spinal cord. The extended increase of the spinal p-ERK might be related to the enhanced pain behavior in the animals with lesions of the spinal serotonergic pathway in the carrageenan model.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School and Hospital, Gwangju, Korea.
authors.forename: Soo Young
authors.initials: SY
authors.lastname: Cho
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School and Hospital, Gwangju, Korea.
authors.forename: Hyoung Gon
authors.initials: HG
authors.lastname: Ki
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School and Hospital, Gwangju, Korea.
authors.forename: Joung Min
authors.initials: JM
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School and Hospital, Gwangju, Korea.
authors.forename: Jin Myung
authors.initials: JM
authors.lastname: Oh
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School and Hospital, Gwangju, Korea.
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Yang
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School and Hospital, Gwangju, Korea.
authors.forename: Woong Mo
authors.initials: WM
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School and Hospital, Gwangju, Korea.
authors.forename: Hyung Gon
authors.initials: HG
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School and Hospital, Gwangju, Korea.
authors.forename: Myung Ha
authors.initials: MH
authors.lastname: Yoon
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School and Hospital, Gwangju, Korea.
authors.forename: Jeong Il
authors.initials: JI
authors.lastname: Choi
keywords: 5-HT7 receptor; Carrageenan; Extracellular signal-regulated kinase; Spinal cord
references.citation: Trends Pharmacol Sci. 2004 Dec;25(12):613-7
references.pmid: 15530638
references.citation: Mol Pain. 2010 Sep 14;6:54
references.pmid: 20840753
references.citation: Pharmacol Biochem Behav. 2011 Oct;99(4):591-7
references.pmid: 21693130
references.citation: Neurosci Lett. 2002 Mar 29;322(1):37-40
references.pmid: 11958838
references.citation: Br J Anaesth. 2014 Jul;113(1):138-47
references.pmid: 24129596
references.citation: Brain Res Mol Brain Res. 2003 Aug 19;116(1-2):126-34
references.pmid: 12941468
references.citation: Neuropharmacology. 2012 Nov;63(6):1093-106
references.pmid: 22820553
references.citation: J Neurosci. 2001 Jun 1;21(11):3771-9
references.pmid: 11356865
references.citation: Acta Pharmacol Sin. 2005 Jul;26(7):789-98
references.pmid: 15960884
references.citation: Exp Brain Res. 1997 Jan;113(1):81-7
references.pmid: 9028777
references.citation: Neurosci Lett. 2004 May 6;361(1-3):229-31
references.pmid: 15135935
references.citation: Brain Res Rev. 2009 Apr;60(1):135-48
references.pmid: 19150373
references.citation: Prog Neurobiol. 2002 Apr;66(6):355-474
references.pmid: 12034378
references.citation: Brain Res. 2008 Jan 2;1187:103-10
references.pmid: 18037394
references.citation: Anesthesiology. 2010 Mar;112(3):696-710
references.pmid: 20179508
references.citation: J Neurosci. 2010 Jun 23;30(25):8624-36
references.pmid: 20573908
references.citation: Pain. 2010 Jun;149(3):483-94
references.pmid: 20399562
references.citation: Br J Pharmacol. 2006 Nov;149(5):498-505
references.pmid: 16921395
references.citation: Eur J Pharmacol. 2010 Dec 15;649(1-3):183-94
references.pmid: 20868676
references.citation: Korean J Pain. 2014 Jan;27(1):23-9
references.pmid: 24478897
references.citation: Pain. 2004 Jul;110(1-2):259-68
references.pmid: 15275776
references.citation: Pain. 2004 Sep;111(1-2):125-35
references.pmid: 15327816
references.citation: Curr Pain Headache Rep. 2006 Apr;10(2):101-6
references.pmid: 16539862
references.citation: Annu Rev Neurosci. 2001;24:737-77
references.pmid: 11520917
references.citation: Endocr Rev. 2001 Apr;22(2):153-83
references.pmid: 11294822
references.citation: J Comp Neurol. 2005 Sep 26;490(3):256-69
references.pmid: 16082681
references.citation: Pain. 2005 Mar;114(1-2):149-59
references.pmid: 15733640
references.citation: Nat Neurosci. 1999 Dec;2(12):1114-9
references.pmid: 10570489
references.citation: FEBS Lett. 2006 Dec 11;580(28-29):6629-34
references.pmid: 17113581