title: trkA modulation of developing somatosensory neurons in oro-facial tissues: tooth pulp fibers are absent in trkA knockout mice.
abstract: To investigate the nerve growth factor requirement of developing oro-facial somatosensory afferents, we have studied the survival of sensory fibers subserving nociception, mechanoreception or proprioception in receptor tyrosine kinase (trkA) knockout mice using immunohistochemistry. trkA receptor null mutant mice lack nerve fibers in tooth pulp, including sympathetic fibers, and showed only sparse innervation of the periodontal ligament. Ruffini endings were formed definitively in the periodontal ligament of the trkA knockout mice, although calcitonin gene-related peptide- and substance P-immunoreactive fibers were reduced in number or had disappeared completely. trkA gene deletion had also no obvious effect on the formation of Meissner corpuscles in the palate. In the vibrissal follicle, however, some mechanoreceptive afferents were sensitive for trkA gene deletion, confirming a previous report [Fundin et al. (1997) Dev. Biol. 190, 94-116]. Moreover, calretinin-positive fibers innervating longitudinal lanceolate endings were completely lost in trkA knockout mice, as were the calretinin-containing parent cells in the trigeminal ganglion.These results indicate that trkA is indispensable for developing nociceptive neurons innervating oral tissues, but not for developing mechanoreceptive neurons innervating oral tissues (Ruffini endings and Meissner corpuscles), and that calretinin-containing, trkA dependent neurons in the trigeminal ganglion normally participate in mechanoreception through longitudinal lanceolate endings of the vibrissal follicle.
authors.affiliation: Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA. matsuos@vet.osakafu-u.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Matsuo
authors.forename: H
authors.initials: H
authors.lastname: Ichikawa
authors.forename: T A
authors.initials: TA
authors.lastname: Henderson
authors.forename: I
authors.initials: I
authors.lastname: Silos-Santiago
authors.forename: M
authors.initials: M
authors.lastname: Barbacid
authors.forename: J J
authors.initials: JJ
authors.lastname: Arends
authors.forename: M F
authors.initials: MF
authors.lastname: Jacquin
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D003782:Dental Pulp / Q000002:abnormalities* / Q000166:cytology / Q000294:innervation; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D007150:Immunohistochemistry; D008410:Masticatory Muscles / Q000002:abnormalities / Q000166:cytology / Q000294:innervation; D008465:Mechanoreceptors / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout / Q000002:abnormalities / Q000235:genetics / Q000378:metabolism; D009470:Muscle Spindles / Q000002:abnormalities / Q000166:cytology; D016900:Neurofilament Proteins / Q000378:metabolism; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism*; D009619:Nociceptors / Q000002:abnormalities* / Q000166:cytology / Q000378:metabolism; D010159:Palate / Q000002:abnormalities / Q000166:cytology / Q000294:innervation; D010513:Periodontal Ligament / Q000002:abnormalities / Q000166:cytology / Q000294:innervation; D020917:Receptor, trkA / Q000172:deficiency* / Q000235:genetics; D009418:S100 Proteins / Q000378:metabolism; D013373:Substance P / Q000378:metabolism; D013869:Thiolester Hydrolases / Q000378:metabolism; D012668:Trigeminal Ganglion / Q000002:abnormalities* / Q000166:cytology / Q000378:metabolism; D043222:Ubiquitin Thiolesterase; D014738:Vibrissae / Q000002:abnormalities* / Q000166:cytology / Q000294:innervation
chemical_list: D002135:Calcium-Binding Proteins; D016900:Neurofilament Proteins; D009418:S100 Proteins; C051774:neurofilament protein H; D013373:Substance P; D004299:Dopamine beta-Hydroxylase; D020917:Receptor, trkA; D013869:Thiolester Hydrolases; D043222:Ubiquitin Thiolesterase; D015740:Calcitonin Gene-Related Peptide