title: Transient receptor potential melastatin (TRPM) 8 is expressed in freshly isolated native human odontoblasts.
abstract: OBJECTIVE
  Cold-sensitive ion channels, such as transient receptor potential melastatin (TRPM) 8 and transient receptor potential ankyrin (TRPA) 1, may play a crucial role in the nociceptive function of odontoblasts, whereas expression of these TRP channels in human native odontoblasts remains to be elucidated. This study aimed to analyze the expression of TRPM8 and TRPA1 in freshly isolated native human odontoblasts.
  
  
  METHODS
  Odontoblasts were isolated from freshly extracted healthy human teeth (n=4); after removing the inner pulp tissues from the pulp chambers, odontoblasts remaining on the dentin surface were washed out with phosphate buffered saline and collected. Reverse transcription-polymerase chain reaction was employed to compare the expression levels of TRPM8, TRPA1, and dentin matrix acidic phosphoprotein 1 (DMP1) mRNAs between the isolated odontoblasts and the inner pulp tissues. The isolated cells were subjected to immunolocalization of TRPM8 and nestin. Paraformaldehyde-fixed, EDTA-demineralized frozen sections obtained from freshly extracted healthy human teeth (n=4) were also analyzed immunohistochemically using anti-nestin, TRPM8, and TRPA1 antibodies.
  
  
  RESULTS
  Expression levels of TRPM8 and DMP1 in the isolated odontoblasts were significantly higher than those in the inner pulp tissues (p<0.05). Expression of TRPM8 and nestin was observed in the odontoblastic layer of the dental pulp tissue and isolated odontoblasts, while expression of TRPA1 was not detected.
  
  
  CONCLUSIONS
  TRPM8, but not TRPA1, was detected in freshly isolated native human odontoblasts at the protein and mRNA levels, suggesting that odontoblasts play an important role in detecting external cold stimulation via TRPM8 in healthy condition.
authors.affiliation: Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
authors.forename: Kento
authors.initials: K
authors.lastname: Tazawa
authors.affiliation: Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan. Electronic address: hms-ikeda.endo@tmd.ac.jp.
authors.forename: Hideharu
authors.initials: H
authors.lastname: Ikeda
authors.affiliation: Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kawashima
authors.affiliation: Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Okiji
mesh_terms: D000328:Adult; D003782:Dental Pulp / Q000166:cytology / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D064231:Nestin / Q000378:metabolism; D009804:Odontoblasts / Q000166:cytology* / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000074025:TRPA1 Cation Channel / Q000378:metabolism; D014070:Tooth / Q000166:cytology
chemical_list: C513309:DMP1 protein, human; D016326:Extracellular Matrix Proteins; D064231:Nestin; D010750:Phosphoproteins; D012333:RNA, Messenger; D000074025:TRPA1 Cation Channel; C473350:TRPA1 protein, human
keywords: Dental pulp; Human; Odontoblast; TRP channels; Thermosensing