GFAP immunoreactivity and transcription in trigeminal and dental tissues of rats and transgenic GFP/GFAP mice.
Sensory mechanisms in teeth are not well understood and may involve pulpal-neural interactions. Tooth cells that proliferate in vitro have polyclonal immunoreactivity (IR) for glial fibrillary acidic protein (GFAP), growth-associated protein (GAP-43), and vimentin, plus glial-like ion channels. Here, we analyzed GFAP-IR patterns in dental and trigeminal tissues of rats, for comparison with green fluorescent protein (GFP) associated with GFAP transcription in transgenic mice, in order to better characterize glial-like cells in dental tissues. Astrocytes, ganglion satellite cells, and epineurial Schwann cells were demonstrated by anti-GFAP antibodies and GFP-GFAP, as expected. Odontoblasts did not stain by any of these methods and cannot be the glial-like cells. Fibroblasts and undifferentiated mesenchymal cells in pulp had polyclonal GFAP-IR and vimentin-IR, while nerve fibers reacted only with polyclonal antibody. Some Schwann cell subtypes in trigeminal nerve and oral mucosa were positive for GFP and for polyclonal anti-GFAP, but not for monoclonal antibody. In pulp almost all Schwann cells were unstained, but many Schwann cells in periodontal ligament had polyclonal GFAP-IR. These results show greater heterogeneity for Schwann cells than expected, and suggest that the glial-like pulp cells are fibroblasts and/or undifferentiated mesenchymal cells or stem cells. We also found that polyclonal GFAP revealed intermediate filaments in preterminal sensory nerve fibers, thereby providing a useful marker for that neural subregion. GFP transcription by some Schwann cell subtypes in oral mucosae and trigeminal nerve, but not trigeminal root was a novel finding that reveals more complexity in peripheral glia than previously recognized.
Byers
Margaret R
MR
Anesthesiology, University of Washington, Seattle, Washington 98195, USA. byersm@u.washington.edu
Maeda
Takeyasu
T
Brown
Angus M
AM
Westenbroek
Ruth E
RE
D000818:Animals; D003782:Dental Pulp / Q000737:chemistry*; D005260:Female; D005881:Gingiva / Q000737:chemistry*; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis* / Q000235:genetics; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009061:Mouth Mucosa / Q000737:chemistry; D009804:Odontoblasts / Q000737:chemistry; D010513:Periodontal Ligament / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014158:Transcription, Genetic; D012668:Trigeminal Ganglion / Q000737:chemistry*; D014746:Vimentin / Q000032:analysis
D005904:Glial Fibrillary Acidic Protein; D014746:Vimentin