title: Expression and coexpression of Trk receptors in subpopulations of adult primary sensory neurons projecting to identified peripheral targets.
abstract: To determine whether neurotrophins act on functionally distinct populations of adult sensory neurons, the distributions of mRNAs for TrkA and tyrosine kinase-containing isoforms of TrkB and TrkC were determined in rat DRG neurons projecting to different peripheral targets. Whereas trkA was expressed by a very high percentage of visceral afferents, trkC was expressed frequently only in muscle afferents. Among cutaneous afferents, the size distributions for trkA- and trkC-positive cells showed little overlap. The percentages and size distributions of cells labeled for the trks argue strongly that almost all trkB-expressing cells must also express trkA or trkC. These results indicate that NGF and NT-3 act on functionally distinct populations of adult sensory neurons and suggest that a sizeable number of small DRG neurons may not respond to neurotrophins via a known Trk in the adult rat.
authors.affiliation: Department of Physiology, St. Thomas' Hospital Medical School, UMDS, London, England.
authors.forename: S B
authors.initials: SB
authors.lastname: McMahon
authors.forename: M P
authors.initials: MP
authors.lastname: Armanini
authors.forename: L H
authors.initials: LH
authors.lastname: Ling
authors.forename: H S
authors.initials: HS
authors.lastname: Phillips
mesh_terms: D000344:Afferent Pathways / Q000378:metabolism; D000375:Aging / Q000378:metabolism; D000818:Animals; D001370:Axonal Transport; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D015870:Gene Expression; D017403:In Situ Hybridization; D008297:Male; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000096:biosynthesis*; D020917:Receptor, trkA; D020813:Receptor, trkB; D020812:Receptor, trkC; D017978:Receptors, Growth Factor / Q000096:biosynthesis*; D017475:Receptors, Nerve Growth Factor / Q000096:biosynthesis*; D012867:Skin / Q000294:innervation
chemical_list: D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D017978:Receptors, Growth Factor; D017475:Receptors, Nerve Growth Factor; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA; D020813:Receptor, trkB; D020812:Receptor, trkC