Peripherin- and CGRP-immunoreactive nerve fibers in rat molars have different locations and developmental timing

Arch Oral Biol. 2006 Sep;51(9):748-60. doi: 10.1016/j.archoralbio.2006.03.011. Epub 2006 May 23.

Abstract

Developing rat molars gain mature sensitivity to electric stimulation at 4-5 weeks after eruption, but the related mechanisms are incompletely understood. Preliminary studies showed weak co-localization of calcitonin gene-related peptide (CGRP) immunoreactivity (IR) with peripherin (PER) or neurofilament protein (NF) in rat molar nerve fibers, while the latter two co-localized extensively.

Objective: Our goal was to compare timing and location of PER-IR and CGRP-IR innervation in rat first molars during tooth maturation.

Methods: We used single and double immunocytochemistry to study molars of rats aged 10 days to 1 year. Neural patterns were compared with odontoblast maturation stages, dentinogenesis, formation of cell-free and cell-rich zones, and root closure.

Results: Spatial and temporal patterns showed that most CGRP-IR and PER-IR have different terminal domains in teeth. PER-IR fibers were well established among immature odontoblasts prior to tooth eruption, but CGRP-IR fibers were absent. Two weeks after eruption of first molars, many CGRP-IR beaded fibers entered dentin, the larger PER-IR fibers began shifting away from odontoblasts towards the pulp, and the symmetrical PER-IR pulpal pattern was being established. The CGRP-IR fibers continued to increase their asymmetric dentinal innervation until root growth was completed, during which time odontoblasts matured, the cell-free and cell-rich zones appeared, and roots closed.

Conclusions: Sensory maturation of rat molars coincides with closed root apices, extensive innervation of dentin by CGRP-IR nerve fibers, and the appearance of the mature avascular odontoblast layer next to cell-free and cell-rich zones in the pulp horns.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomarkers / analysis
  • Calcitonin Gene-Related Peptide / analysis*
  • Dentin / growth & development
  • Dentin / innervation
  • Dentinogenesis / physiology
  • Immunohistochemistry
  • Intermediate Filament Proteins / analysis*
  • Membrane Glycoproteins / analysis*
  • Molar / growth & development*
  • Molar / innervation*
  • Nerve Fibers / metabolism*
  • Nerve Tissue Proteins / analysis*
  • Neurofilament Proteins / analysis
  • Odontoblasts / physiology
  • Odontogenesis / physiology
  • Peripherins
  • Rats
  • Rats, Sprague-Dawley
  • Tooth Eruption

Substances

  • Biomarkers
  • Intermediate Filament Proteins
  • Membrane Glycoproteins
  • Nerve Tissue Proteins
  • Neurofilament Proteins
  • Peripherins
  • Calcitonin Gene-Related Peptide