Expression of vesicular glutamate transporters VGLUT1 and VGLUT2 in the rat dental pulp and trigeminal ganglion following inflammation

PLoS One. 2014 Oct 7;9(10):e109723. doi: 10.1371/journal.pone.0109723. eCollection 2014.

Abstract

Background: There is increasing evidence that peripheral glutamate signaling mechanism is involved in the nociceptive transmission during pathological conditions. However, little is known about the glutamate signaling mechanism and related specific type of vesicular glutamate transporter (VGLUT) in the dental pulp following inflammation. To address this issue, we investigated expression and protein levels of VGLUT1 and VGLUT2 in the dental pulp and trigeminal ganglion (TG) following complete Freund's adjuvant (CFA) application to the rat dental pulp by light microscopic immunohistochemistry and Western blot analysis.

Results: The density of VGLUT2- immunopositive (+) axons in the dental pulp and the number of VGLUT2+ soma in the TG increased significantly in the CFA-treated group, compared to control group. The protein levels of VGLUT2 in the dental pulp and TG were also significantly higher in the CFA-treated group than control group by Western blot analysis. The density of VGLUT1+ axons in the dental pulp and soma in the TG remained unchanged in the CFA-treated group.

Conclusions: These findings suggest that glutamate signaling that is mediated by VGLUT2 in the pulpal axons may be enhanced in the inflamed dental pulp, which may contribute to pulpal axon sensitization leading to hyperalgesia following inflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axons / drug effects*
  • Axons / metabolism
  • Axons / pathology
  • Dental Pulp / drug effects
  • Dental Pulp / metabolism
  • Dental Pulp / physiopathology
  • Freund's Adjuvant / administration & dosage
  • Gene Expression Regulation
  • Glutamic Acid / metabolism*
  • Hyperalgesia / etiology
  • Hyperalgesia / genetics*
  • Hyperalgesia / physiopathology
  • Inflammation / chemically induced
  • Inflammation / complications
  • Inflammation / genetics*
  • Inflammation / physiopathology
  • Male
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction
  • Trigeminal Ganglion / drug effects
  • Trigeminal Ganglion / metabolism
  • Trigeminal Ganglion / physiopathology
  • Vesicular Glutamate Transport Protein 1 / genetics*
  • Vesicular Glutamate Transport Protein 1 / metabolism
  • Vesicular Glutamate Transport Protein 2 / genetics*
  • Vesicular Glutamate Transport Protein 2 / metabolism

Substances

  • Slc17a6 protein, rat
  • Slc17a7 protein, rat
  • Vesicular Glutamate Transport Protein 1
  • Vesicular Glutamate Transport Protein 2
  • Glutamic Acid
  • Freund's Adjuvant

Grants and funding

This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012-0009328). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.