scholarly journals Evaluation of TRPM8 and TRPA1 participation in dental pulp sensitivity to cold stimulation

2017 ◽  
Author(s):  
Benoit Michot ◽  
Caroline Lee ◽  
Eugene Podborits ◽  
Jennifer L. Gibbs
Keyword(s):  
Sensory Neurons ◽  
Trigeminal Ganglion ◽  
Dental Pulp ◽  
Transient Receptor Potential ◽  
Significant Proportion ◽  
Receptor Potential ◽  
Transient Receptor Potential Channels ◽  
Sensory Characteristics ◽  
Cold Stimulation ◽  
Ganglion Neurons

AbstractSensory neurons innervating the dental pulp have unique morphological and functional characteristics compared to neurons innervating other tissues. Stimulation of dental pulp afferents whatever the modality or intensity of the stimulus, even light mechanical stimulation that would not activate nociceptors in other tissues, produces an intense pain. These specific sensory characteristics could involve receptors of the Transient Receptor Potential channels (TRP) family. In this study, we evaluated 1) the expression of TRPA1 and TRPM8 receptors in trigeminal ganglion neurons innervating the dental pulp compared to sensory neurons innervating the oral mucosa or the skin of the face, and 2) the involvement of these receptors in dental pulp sensitivity to cold stimulation. We showed a similar expression of TRPM8 and CGRP in sensory neurons innervating the dental pulp, the skin or the buccal mucosa. On the contrary, TRPA1 was expressed in a higher proportion of neurons innervating the mucosa (43%) than in neurons innervating the dental pulp (19%) or the skin (24%). Moreover, neurons innervating the dental pulp had a higher proportion of large neurons (24%) compared to neurons innervating the skin (8%) or the mucosa (10%). The evaluation of trigeminal ganglion neuron sensitivity to TRPM8 agonist, TRPA1 agonist and cold stimulation, showed that a significant proportion of neurons innervating the skin (10%) or the mucosa (37%) were sensitive to cold stimulation but insensitive to TRPM8 and TRPA1 activation. Similarly, the application of a cold stimulation on the tooth induced an overexpression of cFos in the trigeminal nucleus that was not prevented by administration of a TRPA1 antagonist or the genetic deletion of TRPM8. However, the pretreatment with the local anesthetic carbocaine abolish the cold-induced cFos overexpression. In conclusion, the unique sensory characteristics of the dental pulp would be independent to TRPA1 and TRPM8 expression and functionality.

scholarly journals Transient Receptor Potential Channels Encode Volatile Chemicals Sensed by Rat Trigeminal Ganglion Neurons

PLoS ONE ◽  
2013 ◽  
Vol 8 (10) ◽  
pp. e77998 ◽  
Author(s):  
Matthias Lübbert ◽  
Jessica Kyereme ◽  
Nicole Schöbel ◽  
Leopoldo Beltrán ◽  
Christian Horst Wetzel ◽  
...  
Keyword(s):  
Trigeminal Ganglion ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Transient Receptor Potential Channels ◽  
Volatile Chemicals ◽  
Trigeminal Ganglion Neurons ◽  
Potential Channels ◽  
Transient Receptor ◽  
Ganglion Neurons

scholarly journals Human Dental Pulp Fibroblasts Express the “Cold-sensing” Transient Receptor Potential Channels TRPA1 and TRPM8

2011 ◽  
Vol 37 (4) ◽  
pp. 473-478 ◽  
Author(s):  
Ikhlas A. El Karim ◽  
Gerard J. Linden ◽  
Timothy M. Curtis ◽  
Imad About ◽  
Mary K. McGahon ◽  
...  
Keyword(s):  
Dental Pulp ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Transient Receptor Potential Channels ◽  
Human Dental Pulp ◽  
Potential Channels ◽  
Transient Receptor ◽  
Cold Sensing

scholarly journals Ocular dryness excites two classes of corneal afferent neurons implicated in basal tearing in rats: involvement of transient receptor potential channels

2012 ◽  
Vol 107 (4) ◽  
pp. 1199-1209 ◽  
Author(s):  
Harumitsu Hirata ◽  
Michael L. Oshinsky
Keyword(s):  
Ocular Surface ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Transient Receptor Potential Channels ◽  
Cold Stimulation ◽  
Cold Sensitive ◽  
Hyperosmolar Solutions ◽  
Potential Channels ◽  
Transient Receptor

This study reports the findings of two classes of corneal afferents excited by drying of the cornea (dry responses) in isoflurane-anesthetized rats: cold-sensitive (CS; 87%) and cold-insensitive (CI; 13%) neurons. Compared with CI neurons, CS neurons showed significantly higher firing rates over warmer corneal temperatures (∼31–15°C) and greater responses to menthol, drying, and wetting of the cornea but lower responses when hyperosmolar solutions were applied to the ocular surface. We proposed that the dry responses of these corneal afferents derive from cooling and an increased osmolarity of the ocular surface, leading to the production of basal tears. An ocular application of the transient receptor potential channel TRPM8 antagonist BCTC (20 μM) decreased the dry responses by ∼45–80% but failed to completely block them, whereas the TRPA1 antagonist HC030031 did not influence the responses to drying of the cornea or hyperosmolar tears. Furthermore, the responses produced by cold stimulation of the cornea accounted for only 28% of the dry responses. These results support the view that the stimulus for basal tearing (corneal dryness) derives partly from cooling of the cornea that activates TRPM8 channels but that non-TRPM8 channels also contribute significantly to the dry responses and to basal tearing. Finally, we hypothesized that activation of TRPM8 by cooling in CS corneal afferents not only gives rise to the sensation of ocular coolness but also to the “wetness” perception (Thunberg's illusion), whereas a precise role of the CI afferents in basal tearing and other ocular dryness-related functions such as eye blink and the “dryness” sensation remain to be elucidated.

Effect of increasing temperature on TRPV1-mediated responses in isolated rat pulmonary sensory neurons

2008 ◽  
Vol 294 (3) ◽  
pp. L563-L571 ◽  
Author(s):  
Dan Ni ◽  
Lu-Yuan Lee
Keyword(s):  
Sensory Neurons ◽  
Transient Receptor Potential ◽  
Direct Action ◽  
Receptor Potential ◽  
Transient Receptor Potential Vanilloid ◽  
Trpv1 Channel ◽  
Positive Interaction ◽  
C Fibers ◽  
Ganglion Neurons ◽  
Increasing Temperature

Hyperthermia has been shown to sensitize vagal pulmonary C-fibers in anesthetized rats. However, it was not clear whether the effect was due to a direct action of hyperthermia on these sensory neurons. To answer this question, we carried out this study to determine the effect of increasing temperature on the responses to various chemical stimuli in isolated nodose and jugular ganglion neurons innervating the rat lungs. In the whole cell perforated patch-clamp study, when the temperature was increased from normal (∼36°C) to hyperthermic (∼40.6°C) level of the rat body temperature, the inward currents evoked by capsaicin, a selective activator of the transient receptor potential vanilloid type 1 (TRPV1), and 2-aminoethoxydiphenyl borate (2-APB), a nonselective activator of TRPV1–3 receptors, were both significantly increased. This potentiating effect was clearly present even at a moderate level of hyperthermia (∼39°C). However, only the slow, sustained component of acid-evoked current mediated through the TRPV1 receptor was potentiated by hyperthermia, whereas the rapid, transient component was inhibited. In contrast, the currents evoked by adenosine 5′-triphosphate and acetylcholine, neither of which is known to activate the TRPV1 channel, did not increase when the same temperature elevation was applied. Furthermore, the hyperthermia-induced potentiation of the cell response to 2-APB was significantly attenuated by either capsazepine or AMG 9810, selective TRPV1 antagonists. In conclusion, increasing temperature within the physiological range exerts a potentiating effect on the response to TRPV1 activators in these neurons, which is probably mediated through a positive interaction between hyperthermia and these chemical activators at the TRPV1 channel.

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