title: [Interaction of 5-HT2 and 5-HT3 receptor subtype in 5-HT-induced nociceptive responses in peripheral primary sensory nerve ending].
abstract: OBJECTIVE
  To study the correlation between 5-HT-induced pain response and the contribution by individual 5-HTR subtypes including 5-HT1R, 5-HT2R and 5-HT3R at the level of peripheral primary afferent.
  
  
  METHODS
  The experiments were done on acutely isolated trigeminal ganglion (TG) neurons using whole-cell patch clamp technique and the nociceptive effect was observed on behavior experiments by intraplantar injection of test drugs.
  
  
  RESULTS
  The majority of cells examined responded to 5-HT in a manner of concentration dependence (10(-6) - 10(-3) mol/) (61.4%, 54/88) and with a fast activating and rapid desensitizing inward current (I(5-HT)), which was thought to be mediated by the activation of 5-HT3R, since it could be blocked by 5-HT3R antagonist ICS 205930 and mimicked by 5-HT3R agonist 2-methyl-5-HT. It was found that I(5-HT) was potentiated by 5-HT2R agonist alpha-methyl-5-HT markedly, while 5-HT1R agonist R-(+)-UH 301 did not. In behavioral experiment performed on conscious rats, intraplantar injection of 5-HT(10(-5), 10(-4) and 10(-3) mol/L) induced an increment of cumulative lifting time first 20 min in a manner of concentration dependence. By dissociating 5-HTR subtypes using their corresponding antagonists (ICS and CYP) the potency order of hindpaw lifting time was identified as follows: 5-HT > 5-HT + ICS > 5-HT + CYP.
  
  
  CONCLUSIONS
  The results suggest that in 5-HT-induced nociceptive response at the primary sensory level 5-HT3R may play a role of initiation, but 5-HT2R mediates maintaining and modulatory effect in the processes of nociceptive information convey.
authors.affiliation: Department of Neurobiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Wang-Ping
authors.initials: WP
authors.lastname: Hu
authors.forename: Ke-Chun
authors.initials: KC
authors.lastname: Zhou
authors.forename: Jia-Lie
authors.initials: JL
authors.lastname: Luo
authors.forename: You-Zhen
authors.initials: YZ
authors.lastname: Fan
authors.forename: Li-Qiang
authors.initials: LQ
authors.lastname: Ru
authors.forename: Zhi-Wang
authors.initials: ZW
authors.lastname: Li
mesh_terms: D000818:Animals; D008297:Male; D008564:Membrane Potentials; D010146:Pain / Q000503:physiopathology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D044263:Receptors, Serotonin, 5-HT1 / Q000378:metabolism; D044348:Receptors, Serotonin, 5-HT2 / Q000378:metabolism*; D044406:Receptors, Serotonin, 5-HT3 / Q000378:metabolism*; D011984:Sensory Receptor Cells / Q000378:metabolism* / Q000502:physiology
chemical_list: D044263:Receptors, Serotonin, 5-HT1; D044348:Receptors, Serotonin, 5-HT2; D044406:Receptors, Serotonin, 5-HT3