1
|
Ronan EA, Nagel M, Emrick JJ. The anatomy, neurophysiology, and cellular mechanisms of intradental sensation. Front Pain Res (Lausanne) 2024; 5:1376564. [PMID: 38590718 PMCID: PMC11000636 DOI: 10.3389/fpain.2024.1376564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 03/11/2024] [Indexed: 04/10/2024] Open
Abstract
Somatosensory innervation of the oral cavity enables the detection of a range of environmental stimuli including minute and noxious mechanical forces. The trigeminal sensory neurons underlie sensation originating from the tooth. Prior work has provided important physiological and molecular characterization of dental pulp sensory innervation. Clinical dental experiences have informed our conception of the consequence of activating these neurons. However, the biological role of sensory innervation within the tooth is yet to be defined. Recent transcriptomic data, combined with mouse genetic tools, have the capacity to provide important cell-type resolution for the physiological and behavioral function of pulp-innervating sensory neurons. Importantly, these tools can be applied to determine the neuronal origin of acute dental pain that coincides with tooth damage as well as pain stemming from tissue inflammation (i.e., pulpitis) toward developing treatment strategies aimed at relieving these distinct forms of pain.
Collapse
Affiliation(s)
- Elizabeth A. Ronan
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI, United States
| | - Maximilian Nagel
- Sensory Cells and Circuits Section, National Center for Complementary and Integrative Health, Bethesda, MD, United States
| | - Joshua J. Emrick
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI, United States
| |
Collapse
|
2
|
Thai J, Fuller‐Jackson J, Ivanusic JJ. Using tissue clearing and light sheet fluorescence microscopy for the three-dimensional analysis of sensory and sympathetic nerve endings that innervate bone and dental tissue of mice. J Comp Neurol 2024; 532:e25582. [PMID: 38289188 PMCID: PMC10952626 DOI: 10.1002/cne.25582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 12/05/2023] [Accepted: 12/30/2023] [Indexed: 02/01/2024]
Abstract
Bone and dental tissues are richly innervated by sensory and sympathetic neurons. However, the characterization of the morphology, molecular phenotype, and distribution of nerves that innervate hard tissue has so far mostly been limited to thin histological sections. This approach does not adequately capture dispersed neuronal projections due to the loss of important structural information during three-dimensional (3D) reconstruction. In this study, we modified the immunolabeling-enabled imaging of solvent-cleared organs (iDISCO/iDISCO+) clearing protocol to image high-resolution neuronal structures in whole femurs and mandibles collected from perfused C57Bl/6 mice. Axons and their nerve terminal endings were immunolabeled with antibodies directed against protein gene product 9.5 (pan-neuronal marker), calcitonin gene-related peptide (peptidergic nociceptor marker), or tyrosine hydroxylase (sympathetic neuron marker). Volume imaging was performed using light sheet fluorescence microscopy. We report high-quality immunolabeling of the axons and nerve terminal endings for both sensory and sympathetic neurons that innervate the mouse femur and mandible. Importantly, we are able to follow their projections through full 3D volumes, highlight how extensive their distribution is, and show regional differences in innervation patterns for different parts of each bone (and surrounding tissues). Mapping the distribution of sensory and sympathetic axons, and their nerve terminal endings, in different bony compartments may be important in further elucidating their roles in health and disease.
Collapse
Affiliation(s)
- Jenny Thai
- Department of Anatomy and PhysiologyUniversity of MelbourneParkvilleVictoriaAustralia
| | | | - Jason J. Ivanusic
- Department of Anatomy and PhysiologyUniversity of MelbourneParkvilleVictoriaAustralia
| |
Collapse
|
3
|
Han HM, Jeong SY, Cho YS, Choi SY, Bae YC. Expression of Piezo2 in the dental pulp, sensory root and trigeminal ganglion and it's coexpression with vesicular glutamate transporters. J Endod 2022; 48:1407-1413. [PMID: 35952898 DOI: 10.1016/j.joen.2022.07.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 07/14/2022] [Accepted: 07/21/2022] [Indexed: 01/10/2023]
Abstract
INTRODUCTION Information on the type of vesicular glutamate transporter (VGLUT) that is expressed in the Piezo2-positive (+) neurons in the trigeminal ganglion (TG), and on the type of Piezo2+ axons and their distribution in the dental pulp is important for understanding dental pain elicited by mechanical stimuli and developing new therapeutic strategies. METHODS We examined expression of Piezo2 and its coexpression with VGLUT1 and VGLUT2 in rat TG, sensory root and in human dental pulp by light and electron microscopic immunohistochemistry and quantitative analysis. RESULTS VGLUT1 and VGLUT2 were expressed in the TG neurons. Piezo2 was expressed in axons of all types but primarily in small myelinated (Aδ) axons in the sensory root. In the dental pulp, Piezo2 was expressed densely in the numerous axons that form plexus in the peripheral pulp. Piezo2+ axons in the peripheral pulp were mostly unmyelinated and the Piezo2-immunoreactivity was often concentrated near the axolemma, suggesting that it may represent functional receptors. CONCLUSIONS These findings suggest that 1) VGLUT1 and VGLUT2 are involved in the glutamate signaling in Piezo2+ neurons, 2) Piezo2 may be primarily activated by noxious mechanical stimuli and 3) Piezo2-mediated dental mechanotransduction may be primarily elicited in the peripheral pulp.
Collapse
Affiliation(s)
- Hye Min Han
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Soon Youn Jeong
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Yi Sul Cho
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - So Young Choi
- Department of Oral & Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea.
| |
Collapse
|
4
|
Cho YS, Han HM, Jeong SY, Kim TH, Choi SY, Kim YS, Bae YC. Expression of Piezo1 in the Trigeminal Neurons and in the Axons That Innervate the Dental Pulp. Front Cell Neurosci 2022; 16:945948. [PMID: 35846568 PMCID: PMC9276962 DOI: 10.3389/fncel.2022.945948] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/03/2022] [Indexed: 12/02/2022] Open
Abstract
Information on the neurons and axons that express the mechanosensitive channel Piezo1 and its expression in axons innervating the dental pulp may help understand the nature of the Piezo1-mediated mechanosensation and the underlying mechanism of dentin sensitivity elicited by mechanical stimuli. For this, we here investigated the neurochemical properties of the neurons in the rat trigeminal ganglion (TG) and their axons in its sensory root that express Piezo1 and the expression of Piezo1 in the rat and human dental pulp by light and electron microscopic immunohistochemistry and quantitative analysis. Piezo1 was expressed mainly in medium-sized and large TG neurons. Piezo1-immunopositive (+) neurons frequently coexpressed the marker for neurons with myelinated axons, NF200, but rarely the markers for neurons with unmyelinated axons, CGRP or IB4. In the sensory root of TG, Piezo1 was expressed primarily in small myelinated axons (Aδ, 60.2%) but also in large myelinated (Aβ, 24.3%) and unmyelinated (C, 15.5%) axons. In the human dental pulp, Piezo1 was expressed in numerous NF200+ axons, which formed a network in the peripheral pulp and often “ascended” toward the dentin. Most Piezo1+ myelinated axons in the radicular pulp became unmyelinated in the peripheral pulp, where Piezo1 immunoreaction product was associated with the axonal plasma membrane, suggesting a functional role of Piezo1 in the peripheral pulp. These findings suggest that Piezo1 is involved primarily in mediating the acute pain elicited by high-threshold mechanical stimuli, and that the Piezo1-mediated dental mechanotransduction occurs primarily in the axons in the peripheral pulp.
Collapse
Affiliation(s)
- Yi Sul Cho
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Hye Min Han
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Soon Youn Jeong
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Tae Heon Kim
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - So Young Choi
- Department of Oral & Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Yun Sook Kim
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
- *Correspondence: Yong Chul Bae
| |
Collapse
|
5
|
Tao J, Wang D, Jin A, Xue J, Yu H. Response of the somatosensory cortex following thermal stimuli to dental implants. Neurosci Lett 2022; 784:136750. [PMID: 35728681 DOI: 10.1016/j.neulet.2022.136750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 06/12/2022] [Accepted: 06/17/2022] [Indexed: 11/30/2022]
Abstract
In the current study, we investigated the cortical response of the somatosensory cortex following thermal stimuli to dental implants. Five implants were inserted at the site of the left upper canine with immediate implant placement protocols in five cats. Intrinsic signal optical imaging was applied to measure the cortical responses evoked by thermal sensing via dental implants. The cortical response evoked by 60 g of tactile stimulus to implants was also examined. The response strength and activated location were compared between implants and natural teeth. Thermal stimuli via the implant could evoke reliable cortical responses in the tooth-related region. However, the response amplitude evoked by the cold stimuli applied to the implants was significantly lower than that evoked by the cold stimuli applied to the natural teeth, indicating that the implants were less sensitive to thermal change than the natural tooth. The response evoked by tactile stimuli to implants was significantly stronger than that evoked by cold stimuli. Thermal and tactile stimuli activated the same location of the tooth-related somatosensory cortex in both the implants and natural teeth. Therefore, the thermal change in implants could be detected at the cortical response level. Multimodal sensory integration of thermal and tactile functions existed for implants.
Collapse
Affiliation(s)
- Jianxiang Tao
- Department of Prosthodontics, School & Hospital of Stomatology Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai 200072, China
| | - Duo Wang
- Vision Research Laboratory, School of Life Sciences, The State Key Laboratory of Medical Neurobiology, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200433, China
| | - Anqi Jin
- Vision Research Laboratory, School of Life Sciences, The State Key Laboratory of Medical Neurobiology, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200433, China
| | - Jinlang Xue
- Department of Prosthodontics, School & Hospital of Stomatology Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai 200072, China
| | - Hongbo Yu
- Vision Research Laboratory, School of Life Sciences, The State Key Laboratory of Medical Neurobiology, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200433, China.
| |
Collapse
|
6
|
Ramli R, Norasikin Mohd Nafi S, Azura Ahmad Tarmidzi N, Hasbullah N, Ghani N. Immunohistochemistry as a detection tool for ion channels involved in dental pain signaling. Saudi Dent J 2022. [PMID: 35935722 PMCID: PMC9346947 DOI: 10.1016/j.sdentj.2022.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 11/21/2022] Open
Abstract
Background Despite advances in pain detection, diagnosis, and management, the prevalence of dental pain is still on the rise. Although dental pain is not directly related to fatal outcomes, the two most common types of dental pain—dental caries and dentin hypersensitivity—have a significant impact on an individual’s quality of life. Understanding the mechanism of the pain pathway is one of the crucial steps in providing better treatment for these patients. Ion channels are critical biomolecules that have been the subject of dental study owing to their roles in the transmission and transduction of external stimuli, as well as in the control and perception of pain. Numerous immunohistochemical (IHC) staining approaches have also been used to identify the many ion channels implicated in peripheral pain signaling in dental pulp. Highlight This review highlights the critical steps in IHC and its role in the detection of ion channels involved in the dental pain signaling pathway. Conclusion The key ion channels identified using IHC and whose functions have been widely researched in dental tissues are addressed in this review article.
Collapse
|
7
|
Park SK, Choi SK, Kim YG, Choi SY, Kim JW, Seo SH, Lee JH, Bae YC. Parvalbumin-, substance P- and calcitonin gene-related peptide-immunopositive axons in the human dental pulp differ in their distribution of varicosities. Sci Rep 2020; 10:10672. [PMID: 32606338 DOI: 10.1038/s41598-020-67804-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 06/11/2020] [Indexed: 11/17/2022] Open
Abstract
Information on the frequency and spatial distribution of axonal varicosities associated with release of neurotransmitters in the dental pulp is important to help elucidate the peripheral mechanisms of dental pain, mediated by myelinated versus unmyelinated fibers. For this, we investigated the distribution of axonal varicosities in the human dental pulp using light- and electron-microscopic immunohistochemistry for the vesicular glutamate transporter 2 (VGLUT2), which is involved in the glutamatergic transmission, and syntaxin-1 and synaptosomal nerve-associated protein 25 (SNAP-25), combined with parvalbumin (PV), which is expressed mostly in myelinated axons, and substance P (SP) and calcitonin gene-related peptide (CGRP), which are expressed mostly in unmyelinated axons. We found that the varicosities of the SP- and CGRP-immunopositive (+) axons were uniformly distributed throughout the dental pulp, whereas those of PV+ axons were only dense in the peripheral pulp, and that the expression of PV, VGLUT2, syntaxin-1, SNAP-25, SP and CGRP was significantly higher in the varicosities than in the axonal segments between them. These findings are consistent with the release of glutamate and neuropeptides by axonal varicosities of SP+ and CGRP+ unmyelinated fibers, involved in pulpal pain throughout the human dental pulp, and by varicosities of PV+ fibers, arising from parent myelinated fibers, and involved in dentin sensitivity primarily in the peripheral pulp.
Collapse
|
8
|
Affiliation(s)
- Yong-Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University
| | - Atsushi Yoshida
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University
| |
Collapse
|
9
|
Abstract
The tooth has an unusual sensory system that converts external stimuli predominantly into pain, yet its sensory afferents in teeth demonstrate cytochemical properties of non-nociceptive neurons. This review summarizes the recent knowledge underlying this paradoxical nociception, with a focus on the ion channels involved in tooth pain. The expression of temperature-sensitive ion channels has been extensively investigated because thermal stimulation often evokes tooth pain. However, temperature-sensitive ion channels cannot explain the sudden intense tooth pain evoked by innocuous temperatures or light air puffs, leading to the hydrodynamic theory emphasizing the microfluidic movement within the dentinal tubules for detection by mechanosensitive ion channels. Several mechanosensitive ion channels expressed in dental sensory systems have been suggested as key players in the hydrodynamic theory, and TRPM7, which is abundant in the odontoblasts, and recently discovered PIEZO receptors are promising candidates. Several ligand-gated ion channels and voltage-gated ion channels expressed in dental primary afferent neurons have been discussed in relation to their potential contribution to tooth pain. In addition, in recent years, there has been growing interest in the potential sensory role of odontoblasts; thus, the expression of ion channels in odontoblasts and their potential relation to tooth pain is also reviewed.
Collapse
Affiliation(s)
- Kihwan Lee
- Gachon Pain Center and Department of Physiology, College of Medicine, Gachon University, Incheon 406-799, Korea.
| | - Byeong-Min Lee
- Department of Oral Physiology and Program in Neurobiology, School of Dentistry, Seoul National University, Seoul 08826, Korea.
| | - Chul-Kyu Park
- Gachon Pain Center and Department of Physiology, College of Medicine, Gachon University, Incheon 406-799, Korea.
| | - Yong Ho Kim
- Gachon Pain Center and Department of Physiology, College of Medicine, Gachon University, Incheon 406-799, Korea.
| | - Gehoon Chung
- Department of Oral Physiology and Program in Neurobiology, School of Dentistry, Seoul National University, Seoul 08826, Korea.
- Dental Research Institute, Seoul National University, Seoul 03080, Korea.
| |
Collapse
|
10
|
Hossain MZ, Bakri MM, Yahya F, Ando H, Unno S, Kitagawa J. The Role of Transient Receptor Potential (TRP) Channels in the Transduction of Dental Pain. Int J Mol Sci 2019; 20:ijms20030526. [PMID: 30691193 PMCID: PMC6387147 DOI: 10.3390/ijms20030526] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 01/18/2019] [Accepted: 01/24/2019] [Indexed: 12/18/2022] Open
Abstract
Dental pain is a common health problem that negatively impacts the activities of daily living. Dentine hypersensitivity and pulpitis-associated pain are among the most common types of dental pain. Patients with these conditions feel pain upon exposure of the affected tooth to various external stimuli. However, the molecular mechanisms underlying dental pain, especially the transduction of external stimuli to electrical signals in the nerve, remain unclear. Numerous ion channels and receptors localized in the dental primary afferent neurons (DPAs) and odontoblasts have been implicated in the transduction of dental pain, and functional expression of various polymodal transient receptor potential (TRP) channels has been detected in DPAs and odontoblasts. External stimuli-induced dentinal tubular fluid movement can activate TRP channels on DPAs and odontoblasts. The odontoblasts can in turn activate the DPAs by paracrine signaling through ATP and glutamate release. In pulpitis, inflammatory mediators may sensitize the DPAs. They could also induce post-translational modifications of TRP channels, increase trafficking of these channels to nerve terminals, and increase the sensitivity of these channels to stimuli. Additionally, in caries-induced pulpitis, bacterial products can directly activate TRP channels on DPAs. In this review, we provide an overview of the TRP channels expressed in the various tooth structures, and we discuss their involvement in the development of dental pain.
Collapse
Affiliation(s)
- Mohammad Zakir Hossain
- Department of Oral Physiology, School of Dentistry, Matsumoto Dental University, 1780 Gobara Hirooka, Shiojiri, Nagano 399-0781, Japan.
| | - Marina Mohd Bakri
- Department of Oral and Craniofacial Sciences, Faculty of Dentistry, University of Malaya, Kuala Lumpur 50603, Malaysia.
| | - Farhana Yahya
- Department of Oral and Craniofacial Sciences, Faculty of Dentistry, University of Malaya, Kuala Lumpur 50603, Malaysia.
| | - Hiroshi Ando
- Department of Biology, School of Dentistry, Matsumoto Dental University, 1780 Gobara, Hirooka, Shiojiri, Nagano 399-0781, Japan.
| | - Shumpei Unno
- Department of Oral Physiology, School of Dentistry, Matsumoto Dental University, 1780 Gobara Hirooka, Shiojiri, Nagano 399-0781, Japan.
| | - Junichi Kitagawa
- Department of Oral Physiology, School of Dentistry, Matsumoto Dental University, 1780 Gobara Hirooka, Shiojiri, Nagano 399-0781, Japan.
| |
Collapse
|
11
|
Abstract
Sensory 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 compared the expression of the cold sensitive receptors TRPM8 and TRPA1 in trigeminal ganglion neurons innervating the dental pulp, the skin of the cheek or the buccal mucosa and we evaluated the involvement of these receptors in dental pulp sensitivity to cold. We showed a similar expression of TRPM8, TRPA1 and CGRP in sensory neurons innervating the dental pulp, the skin or the mucosa. Moreover, we demonstrated that noxious cold stimulation of the tooth induced an overexpression of cFos in the trigeminal nucleus that was not prevented by the genetic deletion of TRPM8 or the administration of the TRPA1 antagonist HC030031. These data suggest that the unique sensory characteristics of the dental pulp are independent to TRPM8 and TRPA1 receptors expression and functionality.
Collapse
Affiliation(s)
- Benoit Michot
- Department of Endodontics, New York University College of Dentistry, New York, USA.
| | - Caroline S Lee
- Department of Endodontics, New York University College of Dentistry, New York, USA
| | - Jennifer L Gibbs
- Department of Endodontics, New York University College of Dentistry, New York, USA
| |
Collapse
|
12
|
Bae JY, Mun CJ, Kim YS, Ahn DK, Bae YC. Quantitative ultrastructural analysis of fibers expressing parvalbumin, calretinin, calbindin D-28k, stage specific embryonic antigen-4, and phosphorylated neurofilament 200 in the peripheral sensory root of the rat trigeminal ganglion. J Comp Neurol 2018; 526:2204-2214. [DOI: 10.1002/cne.24476] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 04/02/2018] [Accepted: 05/14/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Jin Young Bae
- Department of Anatomy and Neurobiology, School of Dentistry; Kyungpook National University; Daegu South Korea
| | - Cheol Ju Mun
- Department of Anatomy and Neurobiology, School of Dentistry; Kyungpook National University; Daegu South Korea
| | - Yun Sook Kim
- Department of Anatomy and Neurobiology, School of Dentistry; Kyungpook National University; Daegu South Korea
| | - Dong Kuk Ahn
- Department of Physiology, School of Dentistry; Kyungpook National University; Daegu South Korea
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry; Kyungpook National University; Daegu South Korea
| |
Collapse
|
13
|
Le Fur-Bonnabesse A, Bodéré C, Hélou C, Chevalier V, Goulet JP. Dental pain induced by an ambient thermal differential: pathophysiological hypothesis. J Pain Res 2017; 10:2845-2851. [PMID: 29290692 PMCID: PMC5736355 DOI: 10.2147/jpr.s142539] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Dental pain triggered by temperature differential is a misrecognized condition and a form of dental allodynia. Dental allodynia is characterized by recurrent episodes of diffuse, dull and throbbing tooth pain that develops when returning to an indoor room temperature after being exposed for a long period to cold weather. The pain episode may last up to few hours before subsiding. Effective treatment is to properly shield the pulpal tissue of the offending tooth by increasing the protective layer of the dentin/enamel complex. This review underscores the difference in dentin hypersensitivity and offers a mechanistic hypothesis based on the following processes. Repeated exposure to significant positive temperature gradients (from cold to warm) generates phenotypic changes of dental primary afferents on selected teeth with subsequent development of a “low-grade” neurogenic inflammation. As a result, nociceptive C-fibers become sensitized and responsive to innocuous temperature gradients because the activation threshold of specific TRP ion channels is lowered and central sensitization takes place. Comprehensive overviews that cover dental innervation and sensory modalities, thermodynamics of tooth structure, mechanisms of dental nociception and the thermal pain are also provided.
Collapse
Affiliation(s)
- Anaïs Le Fur-Bonnabesse
- Laboratory of Neurosciences of Brest (EA4685), University of Western Brittany, Brest, France.,Dental School, University of Western Brittany, Brest, France
| | - Céline Bodéré
- Laboratory of Neurosciences of Brest (EA4685), University of Western Brittany, Brest, France.,Dental School, University of Western Brittany, Brest, France.,Assessment and Treatment Center of Pain, Regional and University Hospital Center, Brest, France
| | - Cyrielle Hélou
- Dental School, University of Western Brittany, Brest, France
| | - Valérie Chevalier
- Dental School, University of Western Brittany, Brest, France.,Laboratory IRDL, FRE CNRS 3744, University of Western Brittany, Brest, France
| | | |
Collapse
|
14
|
Kim TH, Park SK, Choi SY, Lee JS, Bae YC. Morphologic Change of Parvalbumin-positive Myelinated Axons in the Human Dental Pulp. J Endod 2017; 43:977-981. [PMID: 28389070 DOI: 10.1016/j.joen.2017.01.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 12/22/2016] [Accepted: 01/09/2017] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Information on the nerve fibers innervating the dental pulp is crucial for understanding dental pain and hypersensitivity. This study investigated the morphologic differences of parvalbumin (PV)-positive (+) myelinated fibers in 3 different regions of the human dental pulp. METHODS Light and electron microscopic immunohistochemistry for parvalbumin, a marker for myelinated fibers, and quantitative analysis were performed in the apical root, core of coronal pulp, and peripheral pulp of human premolar teeth. RESULTS About 40% of the myelinated fibers in the apical root pulp became unmyelinated in the core of the coronal pulp, and virtually all the remaining fibers became unmyelinated at the peripheral pulp. The size of myelinated axons decreased from root to peripheral pulp. PV+ axons showed extensive axonal varicosities in the peripheral pulp. CONCLUSIONS These findings suggest that the myelinated fibers innervating the human dental pulp undergo extensive morphologic change in the extrapulpal region and in the coronal and peripheral pulp, and that PV-mediated regulation of calcium concentration and its downstream events may occur primarily in axonal varicosities in the peripheral pulp.
Collapse
Affiliation(s)
- Tae Heon Kim
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Sook Kyung Park
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - So Young Choi
- Department of Oral & Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Jae Sik Lee
- Department of Pediatric Dentistry, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, South Korea.
| |
Collapse
|
15
|
Kim YS, Kim TH, McKemy DD, Bae YC. Expression of vesicular glutamate transporters in transient receptor potential melastatin 8 (TRPM8)-positive dental afferents in the mouse. Neuroscience 2015; 303:378-88. [PMID: 26166724 DOI: 10.1016/j.neuroscience.2015.07.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 07/01/2015] [Accepted: 07/02/2015] [Indexed: 01/31/2023]
Abstract
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.
Collapse
Affiliation(s)
- Y S Kim
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, South Korea
| | - T H Kim
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, South Korea
| | - D D McKemy
- Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Y C Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, South Korea.
| |
Collapse
|
16
|
Cho Y, Kim Y, Moozhayil S, Yang E, Bae Y. The expression of hyperpolarization-activated cyclic nucleotide-gated channel 1 (HCN1) and HCN2 in the rat trigeminal ganglion, sensory root, and dental pulp. Neuroscience 2015; 291:15-25. [DOI: 10.1016/j.neuroscience.2015.01.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 10/24/2022]
|
17
|
Bae JY, Kim JH, Cho YS, Mah W, Bae YC. Quantitative analysis of afferents expressing substance P, calcitonin gene-related peptide, isolectin B4, neurofilament 200, and Peripherin in the sensory root of the rat trigeminal ganglion. J Comp Neurol 2014; 523:126-38. [DOI: 10.1002/cne.23672] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 08/21/2014] [Accepted: 08/25/2014] [Indexed: 12/19/2022]
Affiliation(s)
- Jin Young Bae
- Department of Anatomy and Neurobiology; School of Dentistry, Kyungpook National University; Daegu 700-412 South Korea
| | - Jae Hyun Kim
- Department of Anatomy and Neurobiology; School of Dentistry, Kyungpook National University; Daegu 700-412 South Korea
| | - Yi Sul Cho
- Department of Anatomy and Neurobiology; School of Dentistry, Kyungpook National University; Daegu 700-412 South Korea
| | - Won Mah
- Department of Anatomy and Neurobiology; School of Dentistry, Kyungpook National University; Daegu 700-412 South Korea
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology; School of Dentistry, Kyungpook National University; Daegu 700-412 South Korea
| |
Collapse
|
18
|
Yang ES, Jin MU, Hong JH, Kim YS, Choi SY, Kim TH, Cho YS, Bae YC. Expression of vesicular glutamate transporters VGLUT1 and VGLUT2 in the rat dental pulp and trigeminal ganglion following inflammation. PLoS One 2014; 9:e109723. [PMID: 25290694 DOI: 10.1371/journal.pone.0109723] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 09/04/2014] [Indexed: 01/07/2023] Open
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.
Collapse
|
19
|
Abstract
Due, in part, to the unique structure of the tooth, dental pain is initiated via distinct mechanisms. Here we review recent advances in our understanding of inflammatory tooth pain and discuss 3 hypotheses proposed to explain dentinal hypersensitivity: The first hypothesis, supported by functional expression of temperature-sensitive transient receptor potential channels, emphasizes the direct transduction of noxious temperatures by dental primary afferent neurons. The second hypothesis, known as hydrodynamic theory, attributes dental pain to fluid movement within dentinal tubules, and we discuss several candidate cellular mechanical transducers for the detection of fluid movement. The third hypothesis focuses on the potential sensory function of odontoblasts in the detection of thermal or mechanical stimuli, and we discuss the accumulating evidence that supports their excitability. We also briefly update on a novel strategy for local nociceptive anesthesia via nociceptive transducer molecules in dental primary afferents with the potential to specifically silence pain fibers during dental treatment. Further understanding of the molecular mechanisms of dental pain would greatly enhance the development of therapeutics that target dental pain.
Collapse
Affiliation(s)
- G Chung
- Pain Cognitive Function Research Center, Dental Research Institute and Department of Neurobiology and Physiology, School of Dentistry, Seoul National University, Seoul 110-749, Republic of Korea
| | | | | |
Collapse
|
20
|
Kovačič U, Tesovnik B, Molnar N, Cör A, Skalerič U, Gašperšič R. Dental pulp and gingivomucosa in rats are innervated by two morphologically and neurochemically different populations of nociceptors. Arch Oral Biol 2013; 58:788-95. [PMID: 23411402 DOI: 10.1016/j.archoralbio.2013.01.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 01/14/2013] [Accepted: 01/17/2013] [Indexed: 12/25/2022]
Abstract
OBJECTIVES Difference in phenotypes of sensory neurons innervating dental pulp or gingivomucosa may be responsible for intense pain sensations in pulpitis in contrast to relatively painless chronic periodontitis. Therefore, we classified these neurons according to their size and two neurochemical characteristics of nociceptors, their TrkA expression and isolectin IB4 binding. DESIGN In rats (n=6) fluorescent tracers Fluorogold and TrueBlue were simultaneously applied into the standard-sized tooth cavity and nearby gingival sulcus, respectively. After the fluorescence on paraffin trigeminal ganglia (TG) sections was identified and photographed, immunohistochemistry for TrkA expression and IB4 binding was performed on the same sections. RESULTS The average sizes of TG neurons projecting to the gingivomucosa and dental pulp were 894±441μm(2) and 1012±381μm(2), respectively. The proportions of small-sized gingival and pulpal neurons were 14% and 5%, respectively (p<0.05). The proportions of TrkA-positive neurons among all gingival or pulpal neurons were 76% and 86%, respectively (p<0.05). Among all gingival or pulpal neurons the proportions of IB4-positive neurons were 46% and 3% (p<0.001), respectively, and the majority of them were small-medium sized. CONCLUSIONS Dental pulp and gingivomucosa are richly innervated by nociceptive TrkA-expressing neurons. However, while great majority of pulpal neurons are larger NGF-dependent A-fibre nociceptors without affinity to bind IB4, almost half of the gingival neurons are smaller IB4 binding C-fibre nociceptors. The difference in phenotype of sensory neurons might partially explain the different sensitivity of both tissues during normal and pathological conditions.
Collapse
Affiliation(s)
- Uroš Kovačič
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 2, 1000 Ljubljana, Slovenia
| | | | | | | | | | | |
Collapse
|
21
|
Zerari-Mailly F, Braud A, Davido N, Touré B, Azérad J, Boucher Y. Glutamate control of pulpal blood flow in the incisor dental pulp of the rat. Eur J Oral Sci 2012; 120:402-7. [DOI: 10.1111/j.1600-0722.2012.00989.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2012] [Indexed: 01/02/2023]
Affiliation(s)
| | - Adeline Braud
- UFR d'Odontologie; Université Diderot; Paris; France
| | - Nicolas Davido
- Service d'Odontologie; Groupe Hospitalier Pitie Salpêtrière; Paris; France
| | - Babacar Touré
- Faculté de Médecine Pharmacie et d'Odontologie; Université Cheikh Anta Diop; Dakar; Sénégal
| | | | | |
Collapse
|
22
|
Vang H, Chung G, Kim HY, Park SB, Jung SJ, Kim JS, Oh SB. Neurochemical properties of dental primary afferent neurons. Exp Neurobiol 2012; 21:68-74. [PMID: 22792027 PMCID: PMC3381214 DOI: 10.5607/en.2012.21.2.68] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Accepted: 04/04/2012] [Indexed: 11/19/2022] Open
Abstract
The long belief that dental primary afferent (DPA) neurons are entirely composed of nociceptive neurons has been challenged by several anatomical and functional investigations. In order to characterize non-nociceptivepopulation among DPA neurons, retrograde transport fluorescent dye was placed in upper molars of rats and immunohistochemical detection of peripherin and neurofilament 200 in the labeled trigeminal ganglia was performed. As the results, majority ofDPA neurons were peripherin-expressing small-sized neurons, showing characteristic ofnociceptive C-fibers. However, 25.7% of DPA were stained with antibody against neurofilament 200, indicating significant portion of DPA neurons are related to large myelinated Aβ fibers. There were a small number of neurons thatexpressed both peripherin and neurofilament 200, suggestive of Aδ fibers. The possible transition of neurochemical properties by neuronal injury induced by retrograde labeling technique was ruled out by detection of minimal expression of neuronal injury marker, ATF-3. These results suggest that in addition to the large population of C-fiber-related nociceptive neurons, a subset of DPA neurons is myelinated large neurons, which is related to low-threshold mechanosensitive Aβ fibers. We suggest that these Aβ fiber-related neurons might play a role as mechanotransducers of fluid movement within dentinal tubules.
Collapse
Affiliation(s)
- Hue Vang
- National Research Laboratory for Pain, Dental Research Institute and Department of Neurobiology and Physiology, School of Dentistry, Seoul National University, Seoul 110-749, Korea
| | | | | | | | | | | | | |
Collapse
|
23
|
Paik SK, Kim SK, Choi SJ, Yang ES, Ahn SH, Bae YC. Vesicular Glutamate Transporters in Axons That Innervate the Human Dental Pulp. J Endod 2012; 38:470-4. [DOI: 10.1016/j.joen.2011.12.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 12/07/2011] [Accepted: 12/08/2011] [Indexed: 11/15/2022]
|
24
|
Henry MA, Luo S, Levinson SR. Unmyelinated nerve fibers in the human dental pulp express markers for myelinated fibers and show sodium channel accumulations. BMC Neurosci 2012; 13:29. [PMID: 22429267 DOI: 10.1186/1471-2202-13-29] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 03/19/2012] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND The dental pulp is a common source of pain and is used to study peripheral inflammatory pain mechanisms. Results show most fibers are unmyelinated, yet recent findings in experimental animals suggest many pulpal afferents originate from fibers that are myelinated at more proximal locations. Here we use the human dental pulp and confocal microscopy to examine the staining relationships of neurofilament heavy (NFH), a protein commonly expressed in myelinated afferents, with other markers to test the possibility that unmyelinated pulpal afferents originate from myelinated axons. Other staining relationships studied included myelin basic protein (MBP), protein gene product (PGP) 9.5 to identify all nerve fibers, tyrosine hydroxylase (TH) to identify sympathetic fibers, contactin-associated protein (caspr) to identify nodal sites, S-100 to identify Schwann cells and sodium channels (NaChs). RESULTS Results show NFH expression in most PGP9.5 fibers except those with TH and include the broad expression of NFH in axons lacking MBP. Fibers with NFH and MBP show NaCh clusters at nodal sites as expected, but surprisingly, NaCh accumulations are also seen in unmyelinated fibers with NFH, and in fibers with NFH that lack Schwann cell associations. CONCLUSIONS The expression of NFH in most axons suggests a myelinated origin for many pulpal afferents, while the presence of NaCh clusters in unmyelinated fibers suggests an inherent capacity for the unmyelinated segments of myelinated fibers to form NaCh accumulations. These findings have broad implications on the use of dental pulp to study pain mechanisms and suggest possible novel mechanisms responsible for NaCh cluster formation and neuronal excitability.
Collapse
|
25
|
Fried K, Sessle BJ, Devor M. The paradox of pain from tooth pulp: low-threshold "algoneurons"? Pain 2011; 152:2685-2689. [PMID: 21889261 DOI: 10.1016/j.pain.2011.08.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 07/24/2011] [Accepted: 08/02/2011] [Indexed: 11/29/2022]
Affiliation(s)
- Kaj Fried
- Department of Dental Medicine, Karolinska Institutet, S-141 04 Huddinge, Sweden Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada M5G 1G6 Department of Cell and Developmental Biology, Institute of Life Sciences and Center for Research on Pain, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | | | | |
Collapse
|
26
|
Yeo EJ, Cho YS, Paik SK, Yoshida A, Park MJ, Ahn DK, Moon C, Kim YS, Bae YC. Ultrastructural analysis of the synaptic connectivity of TRPV1-expressing primary afferent terminals in the rat trigeminal caudal nucleus. J Comp Neurol 2011; 518:4134-46. [PMID: 20878780 DOI: 10.1002/cne.22369] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Trigeminal primary afferents that express the transient receptor potential vanilloid 1 (TRPV1) are important for the transmission of orofacial nociception. However, little is known about how the TRPV1-mediated nociceptive information is processed at the first relay nucleus in the central nervous system (CNS). To address this issue, we studied the synaptic connectivity of TRPV1-positive (+) terminals in the rat trigeminal caudal nucleus (Vc) by using electron microscopic immunohistochemistry and analysis of serial thin sections. Whereas the large majority of TRPV1+ terminals made synaptic contacts of an asymmetric type with one or two postsynaptic dendrites, a considerable fraction also participated in complex glomerular synaptic arrangements. A few TRPV1+ terminals received axoaxonic contacts from synaptic endings that contained pleomorphic synaptic vesicles and were immunolabeled for glutamic acid decarboxylase, the synthesizing enzyme for the inhibitory neurotransmitter γ-aminobutyric acid (GABA). We classified the TRPV1+ terminals into an S-type, containing less than five dense-core vesicles (DCVs), and a DCV-type, containing five or more DCVs. The number of postsynaptic dendrites was similar between the two types of terminals; however, whereas axoaxonic contacts were frequent on the S-type, the DCV-type did not receive axoaxonic contacts. In the sensory root of the trigeminal ganglion, TRPV1+ axons were mostly unmyelinated, and a small fraction was small myelinated. These results suggest that the TRPV1-mediated nociceptive information from the orofacial region is processed in a specific manner by two distinct types of synaptic arrangements in the Vc, and that the central input of a few TRPV1+ afferents is presynaptically modulated via a GABA-mediated mechanism.
Collapse
Affiliation(s)
- Eun Jin Yeo
- Department of Anatomy and Neurobiology, BK21, School of Dentistry, Kyungpook National University, Daegu, Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Bae YC, Yoshida A. Ultrastructural Basis for Craniofacial Sensory Processing in The Brainstem. Translating Mechanisms Orofacial Neurological Disorder. Elsevier; 2011. pp. 99-141. [DOI: 10.1016/b978-0-12-385198-7.00005-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register]
|
28
|
Paik SK, Lee DS, Kim JY, Bae JY, Cho YS, Ahn DK, Yoshida A, Bae YC. Quantitative ultrastructural analysis of the neurofilament 200-positive axons in the rat dental pulp. J Endod 2010; 36:1638-42. [PMID: 20850668 DOI: 10.1016/j.joen.2010.05.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 05/04/2010] [Accepted: 05/19/2010] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Previous studies have suggested that myelinated axons lose their myelin and become thinner in their peripheral course to the target organ. In this study, we investigated the morphologic changes of pulpal myelinated axons between their root portion (radicular pulp) and their terminal area (peripheral pulp). METHODS Sections of pulp of the rat upper molar teeth were immunostained for the marker of myelinated axons neurofilament (NF) 200. The proportion of NF200+ myelinated and unmyelinated fibers and their sizes were analyzed by using quantitative electron microscopy. RESULTS The axon area, myelin thickness, and fraction of NF200+ myelinated axons of all NF200+ axons were significantly lower in peripheral than in radicular pulp. In addition, large unmyelinated axons were frequently observed in peripheral pulp. CONCLUSIONS These results suggest that pulpal innervation originates predominantly from myelinated axons, and the myelinated axons undergo extensive morphologic changes during their course from the radicular to the peripheral pulp.
Collapse
Affiliation(s)
- Sang Kyoo Paik
- Department of Oral Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, Korea
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Tarsa L, Bałkowiec-Iskra E, Kratochvil FJ, Jenkins VK, McLean A, Brown AL, Smith JA, Baumgartner JC, Balkowiec A. Tooth pulp inflammation increases brain-derived neurotrophic factor expression in rodent trigeminal ganglion neurons. Neuroscience 2010; 167:1205-15. [PMID: 20223282 DOI: 10.1016/j.neuroscience.2010.03.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 02/06/2010] [Accepted: 03/02/2010] [Indexed: 12/23/2022]
Abstract
Nociceptive pathways with first-order neurons located in the trigeminal ganglion (TG) provide sensory innervation to the head, and are responsible for a number of common chronic pain conditions, including migraines, temporomandibular disorders and trigeminal neuralgias. Many of those conditions are associated with inflammation. Yet, the mechanisms of chronic inflammatory pain remain poorly understood. Our previous studies show that the neurotrophin brain-derived neurotrophic factor (BDNF) is expressed by adult rat TG neurons, and released from cultured newborn rat TG neurons by electrical stimulation and calcitonin gene-related peptide (CGRP), a well-established mediator of trigeminal inflammatory pain. These data suggest that BDNF plays a role in activity-dependent plasticity at first-order trigeminal synapses, including functional changes that take place in trigeminal nociceptive pathways during chronic inflammation. The present study was designed to determine the effects of peripheral inflammation, using tooth pulp inflammation as a model, on regulation of BDNF expression in TG neurons of juvenile rats and mice. Cavities were prepared in right-side maxillary first and second molars of 4-week-old animals, and left open to oral microflora. BDNF expression in right TG was compared with contralateral TG of the same animal, and with right TG of sham-operated controls, 7 and 28 days after cavity preparation. Our ELISA data indicate that exposing the tooth pulp for 28 days, with confirmed inflammation, leads to a significant upregulation of BDNF in the TG ipsilateral to the affected teeth. Double-immunohistochemistry with antibodies against BDNF combined with one of nociceptor markers, CGRP or transient receptor potential vanilloid type 1 (TRPV1), revealed that BDNF is significantly upregulated in TRPV1-immunoreactive (IR) neurons in both rats and mice, and CGRP-IR neurons in mice, but not rats. Overall, the inflammation-induced upregulation of BDNF is stronger in mice compared to rats. Thus, mouse TG provides a suitable model to study molecular mechanisms of inflammation-dependent regulation of BDNF expression in vivo.
Collapse
Affiliation(s)
- L Tarsa
- Department of Integrative Biosciences, Oregon Health & Science University School of Dentistry, Portland, OR 97239, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Jang JW, Choi SY, Kwon DG, Bae YC, Kim CS, Lee SH. Demyelination of neurofilament protein 200 immune positive never fibers in human pulp. J Korean Assoc Oral Maxillofac Surg 2010. [DOI: 10.5125/jkaoms.2010.36.5.360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Jung-Woo Jang
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - So-Young Choi
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Dae-Geon Kwon
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Yong-Chul Bae
- Department of Oral Histology and Anatomy, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Chin-Soo Kim
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Sang-Han Lee
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Korea
| |
Collapse
|