title: 5-HT7 receptors are involved in mediating 5-HT-induced activation of rat primary afferent neurons.
abstract: The purpose of this study was to determine whether the 5-hydroxytryptamine7 (5-HT7) receptor is expressed by nociceptor-like neurons in the rat PNS and whether 5-HT activates these nociceptors via the 5-HT7 receptor subtype. Using a polyclonal antibody and the method of immunofluorescence staining, we demonstrated that the 5-HT7 receptor appears predominately on "nociceptor-like" neurons of the rat lumbar dorsal root ganglia. Using immunocytochemical methods, we showed that the immunoreactivity of the 5-HT7 receptor antibody complex is localized in the superficial layers of the spinal cord dorsal horn, which corresponds with laminae I, IIouter and IIinner. Furthermore, we demonstrated that noxious stimulation produced by knee injection of 5-HT or a 5-HT7 agonist dose-dependently increases c-Fos production of the rat spinal cord dorsal horn. This effect was significantly inhibited by the preinjection of a 5-HT7 antagonist. We conclude that the 5-HT7 receptor is expressed by rat primary afferent nociceptors which terminate in the superficial layers of the spinal cord dorsal horn and that the 5-HT7 receptor subtype is involved in nociceptor activation by 5-HT.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University of Cologne, D-50924 Cologne, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Meuser
authors.forename: Christian
authors.initials: C
authors.lastname: Pietruck
authors.forename: Anja
authors.initials: A
authors.lastname: Gabriel
authors.forename: Guo-Xi
authors.initials: GX
authors.lastname: Xie
authors.forename: Kyung-Joon
authors.initials: KJ
authors.lastname: Lim
authors.forename: Pamela
authors.initials: P
authors.lastname: Pierce Palmer
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D019084:Fluorescent Antibody Technique, Indirect; D007270:Injections, Intra-Articular; D007719:Knee Joint; D008161:Lumbosacral Region; D008297:Male; D008719:Methiothepin / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D020671:Posterior Horn Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000032:analysis / Q000378:metabolism*; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; C104425:serotonin 7 receptor; D012701:Serotonin; D008719:Methiothepin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin