title: 5-HT(1D) receptor immunoreactivity in the sphenopalatine ganglion: implications for the efficacy of triptans in the treatment of autonomic signs associated with cluster headache.
abstract: OBJECTIVE
  To determine if 5-HT(1D) receptors are located in the sphenopalatine ganglion.
  
  
  BACKGROUND
  While the 5-HT(1D) receptor has been described in sensory and sympathetic ganglia in the head, it was not known whether they were also located in parasympathetic ganglia.
  
  
  METHODS
  We used retrograde labeling combined with immunohistochemistry to examine 5-HT(1D) receptor immunoreactivity in rat sphenopalatine ganglion neurons that project to the lacrimal gland, nasal mucosa, cerebral vasculature, and trigeminal ganglion.
  
  
  RESULTS
  We found 5-HT(1D) receptor immunoreactivity in nerve terminals around postganglionic cell bodies within the sphenopalatine ganglion. All 5-HT(1D) -immunoreactive terminals were also immunoreactive for calcitonin gene-related peptide but not vesicular acetylcholine transporter, suggesting that they were sensory and not preganglionic parasympathetic fibers. Our retrograde labeling studies showed that approximately 30% of sphenopalatine ganglion neurons innervating the lacrimal gland, 23% innervating the nasal mucosa, and 39% innervating the trigeminal ganglion were in apparent contact with 5-HT(1D) receptor containing nerve terminals.
  
  
  CONCLUSIONS
  These data suggest that 5-HT(1D) receptors within primary afferent neurons that innervate the sphenopalatine ganglion are in a position to modulate the excitability of postganglionic parasympathetic neurons that innervate the lacrimal gland and nasal mucosa, as well as the trigeminal ganglion. This has implications for triptan (5-HT(1D) receptor agonist) actions on parasympathetic symptoms in cluster headache.
authors.affiliation: From the Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Australia (J.J. Ivanusic, M.M.K. Kwok, E.A. Jennings); School of Dentistry James Cook University, Cairns, Queensland, Australia (E.A. Jennings); Department of Neurology, University of Florida College of Medicine, Gainesville, FL, USA (A.H. Ahn).
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Ivanusic
authors.affiliation: From the Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Australia (J.J. Ivanusic, M.M.K. Kwok, E.A. Jennings); School of Dentistry James Cook University, Cairns, Queensland, Australia (E.A. Jennings); Department of Neurology, University of Florida College of Medicine, Gainesville, FL, USA (A.H. Ahn).
authors.forename: Matthew M K
authors.initials: MMK
authors.lastname: Kwok
authors.affiliation: From the Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Australia (J.J. Ivanusic, M.M.K. Kwok, E.A. Jennings); School of Dentistry James Cook University, Cairns, Queensland, Australia (E.A. Jennings); Department of Neurology, University of Florida College of Medicine, Gainesville, FL, USA (A.H. Ahn).
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Ahn
authors.affiliation: From the Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Australia (J.J. Ivanusic, M.M.K. Kwok, E.A. Jennings); School of Dentistry James Cook University, Cairns, Queensland, Australia (E.A. Jennings); Department of Neurology, University of Florida College of Medicine, Gainesville, FL, USA (A.H. Ahn).
authors.forename: Ernest A
authors.initials: EA
authors.lastname: Jennings
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000503:physiopathology*; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D003027:Cluster Headache / Q000188:drug therapy* / Q000503:physiopathology; D005726:Ganglia, Parasympathetic / Q000378:metabolism*; D007150:Immunohistochemistry; D007765:Lacrimal Apparatus / Q000294:innervation; D023421:Models, Animal; D009297:Nasal Mucosa / Q000294:innervation; D021362:Palate, Hard / Q000294:innervation*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044346:Receptor, Serotonin, 5-HT1D / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D013100:Sphenoid Bone / Q000294:innervation*; D016896:Treatment Outcome; D014363:Tryptamines / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D044346:Receptor, Serotonin, 5-HT1D; D014363:Tryptamines; D015740:Calcitonin Gene-Related Peptide