Vesicular Glutamate Transporters in Axons That Innervate the Human Dental Pulp

Paik, Sang Kyoo; Kim, Sung Kuk; Choi, Su Jung; Yang, Eun Sun; Ahn, Sun Ho; Bae, Yong Chul

doi:10.1016/j.joen.2011.12.012

Cited by 15 publications

(10 citation statements)

References 29 publications

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“…The release of glutamate from nociceptive pulpal axons may be analogous to the inflammation-induced glutamate release from peripheral axons, which induces pain (Omote et al, 1998; deGroot et al, 2000). The expression of VGLUT1 and VGLUT2 in the mouse pulpal axons in the present study is at variance with our previous report (Paik et al, 2012), showing a small number of VGLUT2+ axons in the human dental pulp, possibly due to differences in species or antibodies.…”

Section: Discussioncontrasting

confidence: 99%

Expression of vesicular glutamate transporters in transient receptor potential melastatin 8 (TRPM8)-positive dental afferents in the mouse

Kim

McKemy

et al. 2015

Neuroscience

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Transient receptor potential melastatin 8 (TRPM8) is activated by innocuous cool and noxious cold and plays a crucial role in cold-induced acute pain and pain hypersensitivity. To help understand the mechanism of TRPM8-mediated cold perception under normal and pathologic conditions, we used light microscopic immunohistochemistry and Western blot analysis in mice expressing a genetically encoded axonal tracer in TRPM8-positive (+) neurons. We investigated the coexpression of TRPM8 and vesicular glutamate transporter 1 (VGLUT1) and VGLUT2 in the trigeminal ganglion (TG) and the dental pulp before and after inducing pulpal inflammation. Many TRPM8+ neurons in the TG and axons in the dental pulp expressed VGLUT2, while none expressed VGLUT1. TRPM8+ axons were dense in the pulp horn and peripheral pulp and also frequently observed in the dentinal tubules. Following pulpal inflammation, the proportion of VGLUT2+ and of VGLUT2+/TRPM8+ neurons increased significantly, whereas that of TRPM8+ neurons remained unchanged. Our findings suggest the existence of VGLUT2 (but not VGLUT1)-mediated glutamate signaling in TRPM8+ neurons possibly underlying the cold-induced acute pain and hypersensitivity to cold following pulpal inflammation.

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Section: Discussioncontrasting

confidence: 99%

Expression of vesicular glutamate transporters in transient receptor potential melastatin 8 (TRPM8)-positive dental afferents in the mouse

Kim

McKemy

et al. 2015

Neuroscience

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“…It has been shown that VGLUT1 and VGLUT2 are expressed in many pulpal axons, suggesting that VGLUT1-as well as VGLUT2-mediated glutamate signaling is involved in pulpal nociception [4]. Since VGLUT1 is primarily expressed in mechanosensitive neurons (see above) and dental pulp is primarily involved in nociception, it is assumed that VGLUT1 is expressed in a specific subset of sensory afferents (Aβ low-threshold mechanosensitive) in dental pulp that are involved in nociception.…”

Section: Pulpal Axons Express Vglut1 and Vglut2mentioning

confidence: 99%

“…VGLUT and soluble NSF attachment protein receptor (SNARE), which are two classes of proteins associated with synaptic vesicle exocytosis, are densely expressed in the varicosities of pulpal axons, suggesting that glutamate may be released from the pulpal axons at those varicosities (similar to the terminals of the central axons in the spinal cord, which are the sites for transmitter glutamate release) [4,6,7,[62][63][64]. Reportedly, many axons possessing varicosities expressed VGLUT in the peripheral pulp and many of those axons entered the dentinal tubules [4]. Taken together with another observation that metabotropic glutamate receptor 5 (mGluR5) is also expressed in axons in the peripheral pulp [63], it suggests that the primary site of glutamate signaling associated with dental nociception is the peripheral pulp.…”

Section: Pulpal Axons Express Vglut1 and Vglut2mentioning

confidence: 99%

“…Elucidation of the types and properties of nerve fibers innervating dental pulp and of the sensory receptors and ion channels expressed in each type of pulpal nerve fiber is crucial for understanding the peripheral mechanisms of dental pain. Recently, many studies have reported expressions of glutamate receptors and various molecules involved in the release of glutamate in pulpal axons [4,5] and their upregulation in inflamed pulp [6,7]. This suggests that glutamate signaling, associated with the pulpal nerve may play a crucial role in acute and pathologic dental pain.…”

Section: Introductionmentioning

confidence: 99%

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Morphological foundations of pain processing in dental pulp

Bae

Yoshida

2020

J Oral Sci

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Dental pulp is densely innervated by sensory afferents that are primarily involved in nociception. Elucidating the type and properties of these afferents and their distribution patterns within the dental pulp is crucial for understanding the mechanisms of acute dental pain and dental hypersensitivity. Recent studies on the release of the transmitter glutamate and the expression of glutamate receptors and vesicular glutamate transporters (VGLUT) in the pulpal axons and trigeminal ganglion (TG) have suggested the possibility of a distinct glutamate signaling mechanism underlying the peripheral processing of dental pain. This review discusses recent findings on the innervation of dental pulp and glutamate signaling by pulpal axons. First, recent findings on the morphological features and types of axons innervating the dental pulp are summarized. Then, glutamate signaling in the dental pulp and changes in the expression of VGLUT1 and VGLUT2 in the pulpal axons and TG neurons following pulpal inflammation are explained. Finally, findings on glutamate release from odontoblasts are briefly described.

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“…Recent studies reported that the dental pulp is also innervated by a few Aβ low threshold mechanoreceptive (LTM) fibers, which may be involved in the nociception rather than in mechanosensation [17] , [18] . Recently, we reported expression of VGLUT1 as well as VGLUT2 in the axons of the normal human dental pulp and that the VGLUT1 is expressed in larger number of pulpal axons than axons expressing VGLUT2, suggesting larger role of VGLUT1 than VGLUT2 in the transduction of acute nociception in the dental pulp [19] . Previous many studies have focused on the central signaling mechanism for pulpal inflammatory pain, which is dependent on glutamate.…”

Section: Introductionmentioning

confidence: 95%

Expression of Vesicular Glutamate Transporters VGLUT1 and VGLUT2 in the Rat Dental Pulp and Trigeminal Ganglion following Inflammation

et al. 2014

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BackgroundThere 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.ResultsThe 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.ConclusionsThese 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.

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Vesicular Glutamate Transporters in Axons That Innervate the Human Dental Pulp

Cited by 15 publications

References 29 publications

Expression of vesicular glutamate transporters in transient receptor potential melastatin 8 (TRPM8)-positive dental afferents in the mouse

Expression of vesicular glutamate transporters in transient receptor potential melastatin 8 (TRPM8)-positive dental afferents in the mouse

Morphological foundations of pain processing in dental pulp

Expression of Vesicular Glutamate Transporters VGLUT1 and VGLUT2 in the Rat Dental Pulp and Trigeminal Ganglion following Inflammation

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