title: Demonstration of substance P, calcitonin gene-related peptide, and protein gene product 9.5 containing nerve fibers in human cervical facet joint capsules.
abstract: METHODS
  Human cervical facet joint capsules were evaluated by immunohistochemistry.
  
  
  OBJECTIVE
  To study the neuropeptide innervation of the cadaveric cervical facet joint capsules.
  
  
  BACKGROUND
  Various clinical and biomechanical studies indicate a role for cervical facet joint capsules in the etiology of neck pain. However, studies on innervation of these capsules are very limited. There is also a dearth of studies on the neuropeptide nature of this innervation.
  
  
  METHODS
  Facet joint capsules harvested from unembalmed cadavers were studied by the avidin biotin peroxidase method for the presence of nerve fibers. Neuropeptide innervation was investigated by using antisera to substance P and calcitonin gene-related peptide. Antisera to protein gene product 9.5 (PGP 9.5), a general neuronal marker, were also used.
  
  
  RESULTS
  In a study of 12 human cervical facet joint capsules, short segments of substance P were observed in 6 capsules, while fibers reactive to calcitonin gene-related peptide were demonstrated in 7 capsules. Nerve fibers immunoreactive to protein gene product 9.5 were also observed in 9 of the 14 capsules studied. Protein gene product 9.5 reactive fibers were the most extensively distributed fibers, observed as bundles and also as single fibers.
  
  
  CONCLUSIONS
  An abundance of protein gene product 9.5 reactive nerve fibers indicates an extensive innervation of the cervical facet joint capsules. The presence of substance P and calcitonin gene-related peptide reactive nerve fibers in a population of these lends credence to cervical facet joint capsules as a key source of neck pain.
authors.affiliation: Bioengineering Center, Wayne State University, Detroit, MI 48202, USA. kallak@rrb.eng.wayne.edu
authors.forename: Srinivasu
authors.initials: S
authors.lastname: Kallakuri
authors.forename: Anita
authors.initials: A
authors.lastname: Singh
authors.forename: Chaoyang
authors.initials: C
authors.lastname: Chen
authors.forename: John M
authors.initials: JM
authors.lastname: Cavanaugh
mesh_terms: D000368:Aged; D015740:Calcitonin Gene-Related Peptide / Q000032:analysis / Q000276:immunology; D002574:Cervical Vertebrae / Q000294:innervation*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017746:Joint Capsule / Q000294:innervation*; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000737:chemistry*; D009479:Neuropeptides / Q000032:analysis*; D013373:Substance P / Q000032:analysis / Q000276:immunology; D043222:Ubiquitin Thiolesterase / Q000032:analysis / Q000276:immunology
chemical_list: D009479:Neuropeptides; C482860:UCHL1 protein, human; D013373:Substance P; D043222:Ubiquitin Thiolesterase; D015740:Calcitonin Gene-Related Peptide