title: Sympathetic nerve fibers sprout into rat odontoblast layer, but not into dentinal tubules, in response to cavity preparation.
abstract: This study was designed to determine if sympathetic nerve fibers exist in dentinal tubules in rat normal dental pulp, and if they sprout into the dentinal tubules in response to artificial cavity preparation in dentin. Sympathetic nerve fibers in rat molar dental pulp were labeled using an anterograde axonal transport technique involving injection of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) into the superior cervical ganglion (SCG). They were then observed using light and electron microscopes. In normal dental pulp (control), scattered WGA-HRP reaction products were observed in unmyelinated nerve endings in the odontoblast layer and subodontoblastic region. In injured pulp 3 weeks after cavity preparation, reaction products were about 1.8-times more plentiful in the above areas (versus control pulp). However, no labeled nerve fibers were observed in the dentinal tubules in either control or injured dental pulp. These results indicate that although sympathetic nerve fibers do indeed sprout in rat dental pulp in response to cavity preparation, they do not penetrate into the dentinal tubules in which postganglionic nerve endings derived from the SCG were not originally present.
authors.affiliation: Division of Oral Diagnosis, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Shimeno
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Sugawara
authors.forename: Masahiro
authors.initials: M
authors.lastname: Iikubo
authors.forename: Noriaki
authors.initials: N
authors.lastname: Shoji
authors.forename: Takashi
authors.initials: T
authors.lastname: Sasano
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology; D003786:Dental Pulp Cavity / Q000294:innervation* / Q000473:pathology; D003804:Dentin / Q000294:innervation* / Q000473:pathology / Q000648:ultrastructure; D020439:Growth Cones / Q000502:physiology* / Q000648:ultrastructure; D008297:Male; D046529:Microscopy, Electron, Transmission; D009411:Nerve Endings / Q000502:physiology / Q000648:ultrastructure; D009473:Neuronal Plasticity / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology / Q000648:ultrastructure; D009619:Nociceptors / Q000502:physiology / Q000648:ultrastructure; D009804:Odontoblasts / Q000502:physiology* / Q000648:ultrastructure; D010146:Pain / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D017779:Sympathetic Fibers, Postganglionic / Q000166:cytology / Q000502:physiology*; D014070:Tooth / Q000294:innervation* / Q000473:pathology / Q000648:ultrastructure; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
chemical_list: D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate