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Capsaicin, acid and heat-evoked currents in rat trigeminal ganglion neurons: relationship to functional VR1 receptors.

Publication ,  Journal Article
Liu, L; Simon, SA
Published in: Physiol Behav
May 2000

Activation of primary trigeminal (TG) neurons by protons, capsaicin, or heat can evoke a variety of sensations, including tingling, stinging, warmth, and burning. Capsaicin and acid are trigeminal stimulants that are important in gustatory physiology. These stimuli can activate H(+)-gated ion channels and heterologously expressed VR1 receptors (vanilloid receptor 1). We have obtained evidence by using electrophysiological and pharmacological measurements on TG neurons that these three stimuli can activate many receptors, and we have determined the extent they behave similarly to VR1 receptors and H(+)-gated channels from the DEGenerin/ENaC superfamily. Whole-cell recordings from rat TG neurons revealed that protons evoked transient (Tp), sustained (Sp), and biphasic (TSp) currents. Tp currents had reversal potentials (Vr) of 24-45 mV, a pH(0.5) range from 5.5 to 6.5, and were inhibited by amiloride, suggesting the presence of functional H(+)-gated channels. Sp currents were inhibited by the VR1 antagonist capsazepine, had Vr's approximately 0 mV, and had pH(0.5) = 6.4. Capsaicin also activated transient (Tc), sustained (Sc), and biphasic (TSc) currents. At pH 5.9, the sensitivity of the Sc currents increased by about a factor of 10, which may partially account for the synergistic responses of acid in foods containing capsaicin. Heating TG neurons evoked a thermally active, capsazepine-inhibitable current with threshold temperature of 43 degrees C and Vr = 5 mV that is also present in neurons activated by and protons (Sp) and capsaicin (Sc). These data suggest that TG neurons have functional receptors that behave similarly to VR1. Activation of such receptors should result in a burning sensation, whereas activation of the transient and biphasic currents should result in other taste descriptors.

Duke Scholars

Published In

Physiol Behav

DOI

ISSN

0031-9384

Publication Date

May 2000

Volume

69

Issue

3

Start / End Page

363 / 378

Location

United States

Related Subject Headings

  • Trigeminal Ganglion
  • Tachyphylaxis
  • TRPV Cation Channels
  • Reverse Transcriptase Polymerase Chain Reaction
  • Receptors, Drug
  • Rats, Sprague-Dawley
  • Rats
  • Patch-Clamp Techniques
  • Nociceptors
  • Neurons
 

Citation

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Liu, L., & Simon, S. A. (2000). Capsaicin, acid and heat-evoked currents in rat trigeminal ganglion neurons: relationship to functional VR1 receptors. Physiol Behav, 69(3), 363–378. https://doi.org/10.1016/s0031-9384(00)00209-2
Liu, L., and S. A. Simon. “Capsaicin, acid and heat-evoked currents in rat trigeminal ganglion neurons: relationship to functional VR1 receptors.Physiol Behav 69, no. 3 (May 2000): 363–78. https://doi.org/10.1016/s0031-9384(00)00209-2.
Liu, L., and S. A. Simon. “Capsaicin, acid and heat-evoked currents in rat trigeminal ganglion neurons: relationship to functional VR1 receptors.Physiol Behav, vol. 69, no. 3, May 2000, pp. 363–78. Pubmed, doi:10.1016/s0031-9384(00)00209-2.
Journal cover image

Published In

Physiol Behav

DOI

ISSN

0031-9384

Publication Date

May 2000

Volume

69

Issue

3

Start / End Page

363 / 378

Location

United States

Related Subject Headings

  • Trigeminal Ganglion
  • Tachyphylaxis
  • TRPV Cation Channels
  • Reverse Transcriptase Polymerase Chain Reaction
  • Receptors, Drug
  • Rats, Sprague-Dawley
  • Rats
  • Patch-Clamp Techniques
  • Nociceptors
  • Neurons