title: Calcitonin gene-related peptide (CGRP) and its receptor components in human and rat spinal trigeminal nucleus and spinal cord at C1-level.
abstract: BACKGROUND
  Calcitonin gene-related peptide (CGRP) has a key role in migraine pathophysiology and is associated with activation of the trigeminovascular system. The trigeminal ganglion, storing CGRP and its receptor components, projects peripheral to the intracranial vasculature and central to regions in the brainstem with Aδ- and C-fibers; this constitutes an essential part of the pain pathways activated in migraine attacks. Therefore it is of importance to identify the regions within the brainstem that processes nociceptive information from the trigeminovascular system, such as the spinal trigeminal nucleus (STN) and the C1-level of the spinal cord. Immunohistochemistry was used to study the distribution and relation between CGRP and its receptor components - calcitonin receptor-like receptor (CLR) and receptor activity modifying protein 1 (RAMP1) - in human and rat STN and at the C1-level, using a set of newly well characterized antibodies. In addition, double-stainings with CGRP and myelin basic protein (MBP, myelin), synaptophysin (synaptic vesicles) or IB4 (C-fibers in general) were performed.
  
  
  RESULTS
  In the STN, the highest density of CGRP immunoreactive fibers were found in a network around fiber bundles in the superficial laminae. CLR and RAMP1 expression were predominately found in fibers in the spinal trigeminal tract region, with some fibers spanning into the superficial laminae. Co-localization between CGRP and its receptor components was not noted. In C1, CGRP was expressed in fibers of laminae I and II. The CGRP staining was similar in rat, except for CGRP positive neurons that were found close to the central canal. In C1, the receptor components were detected in laminae I and II, however these fibers were distinct from fibers expressing CGRP as verified by confocal microscopy.
  
  
  CONCLUSIONS
  This study demonstrates the detailed expression of CGRP and its receptor components within STN in the brainstem and in the spinal cord at C1-level, and shows the possibility of CGRP acting postjunctionally in these areas putatively involved in primary headaches.
authors.affiliation: Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden. Sajedeh.Eftekhari@med.lu.se
authors.forename: Sajedeh
authors.initials: S
authors.lastname: Eftekhari
authors.forename: Lars
authors.initials: L
authors.lastname: Edvinsson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002102:Cadaver; D015740:Calcitonin Gene-Related Peptide / Q000235:genetics / Q000378:metabolism*; D058286:Calcitonin Receptor-Like Protein / Q000378:metabolism; D002574:Cervical Vertebrae; D004396:Coloring Agents; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D004676:Myelin Basic Protein / Q000378:metabolism; D036421:Nerve Fibers, Unmyelinated / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D058262:Receptor Activity-Modifying Protein 1 / Q000378:metabolism; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000235:genetics / Q000378:metabolism*; D016707:Tissue Fixation; D014278:Trigeminal Nuclei / Q000378:metabolism*; D014279:Trigeminal Nucleus, Spinal / Q000378:metabolism*
chemical_list: D058286:Calcitonin Receptor-Like Protein; D004396:Coloring Agents; D004676:Myelin Basic Protein; C545502:RAMP1 protein, human; C545508:Ramp1 protein, rat; D058262:Receptor Activity-Modifying Protein 1; D018015:Receptors, Calcitonin Gene-Related Peptide; D015740:Calcitonin Gene-Related Peptide
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