title: Immunohistochemical localization of the high-affinity NGF receptor (gp140-trkA) in the adult human dorsal root and sympathetic ganglia and in the nerves and sensory corpuscles supplying digital skin.
abstract: BACKGROUND
  Nerve growth factor (NGF) is produced in target tissues of sympathetic and neural-crest derived sensory neurons, including skin, to provide them trophic support. The biological effects of NGF on responsive cells are mediated by specific high-affinity receptors. Recently, a protein tyrosine kinase of congruent to 140 kDa molecular weight, encoded by the proto-oncogene trkA, has been identified as the high-affinity NGF receptor (gp140-trkA). The present work was undertaken to study the localization of gp140-trkA-like immunoreactivity (IR) in human peripheral ganglia (sympathetic and dorsal root ganglia), and in glabrous skin.
  
  
  METHODS
  Lumbar dorsal root ganglia, para- and prevertebral sympathetic ganglia, and digital glabrous skin were studied immunohistochemically using a rabbit anti-gp140-trkA polyclonal antibody. In order to accurately establish the localization of gp140-trkA IR, the neurofilament proteins and S-100 protein were studied in parallel in: (1) sensory and sympathetic ganglia, to label neuron cell bodies and satellite or supporting cells, respectively; (2) human skin, to label axons, Schwann and related cells within nerves and sensory corpuscles. Moreover, a quantitative study (neuron size, intensity of immunostaining) was carried out on sympathetic and dorsal root ganglia neuron cell bodies.
  
  
  RESULTS
  A specific gp140-trkA-like IR was found in: (1) a subpopulation (65%) of primary sensory neuron cell bodies, including most of the large-sized ones but also small- and intermediate-sized ones; (2) most of sympathetic neuron cell bodies (82%); (3) the perineurial cell, Schwann cells, and large axons of the nerve trunks supplying digital skin; (4) the lamellar cells of Meissner corpuscles; (5) the central axon, inner-core, outer-core, and capsule of Pacinian corpuscles. In addition, the occurrence of gp140-trkA-like IR was observed in some non-nervous tissues of the skin, including epidermis (mainly in the basal layer), sweat glands, and arterial blood vessels.
  
  
  CONCLUSIONS
  Present results provide evidence for the localization of gp140-trkA-like IR in: (1) nerve cells which are known to be NGF-responsive, and (2) non-nervous cutaneous tissues which are innervated by NGF-dependent peripheral neurons. These findings suggest that, in addition to the well-established role of NGF on sensory and sympathetic neurons, this neurotrophin may be able to regulate some other functions on non-nervous cells which are targets for NGF-dependent peripheral neurons.
authors.affiliation: Departamento de Morfología y Biología Celular, Universidad de Oviedo, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Vega
authors.forename: E
authors.initials: E
authors.lastname: Vazquez
authors.forename: F J
authors.initials: FJ
authors.lastname: Naves
authors.forename: M E
authors.initials: ME
authors.lastname: Del Valle
authors.forename: B
authors.initials: B
authors.lastname: Calzada
authors.forename: J J
authors.initials: JJ
authors.lastname: Represa
mesh_terms: D000328:Adult; D005727:Ganglia, Spinal / Q000737:chemistry* / Q000166:cytology; D005728:Ganglia, Sympathetic / Q000737:chemistry* / Q000166:cytology; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009475:Neurons, Afferent / Q000737:chemistry* / Q000166:cytology; D016612:Paraffin Embedding; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000032:analysis*; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis*; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000032:analysis*; D012867:Skin / Q000737:chemistry / Q000166:cytology / Q000294:innervation*
chemical_list: C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D017475:Receptors, Nerve Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA