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See LP, Sripinun P, Lu W, Li J, Alboloushi N, Alvarez-Periel E, Lee SM, Karabucak B, Wang S, Jordan Sciutto KL, Theken KN, Mitchell CH. Increased Purinergic Signaling in Human Dental Pulps With Inflammatory Pain is Sex-Dependent. THE JOURNAL OF PAIN 2024; 25:1039-1058. [PMID: 37956743 PMCID: PMC11129867 DOI: 10.1016/j.jpain.2023.10.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 09/22/2023] [Accepted: 10/28/2023] [Indexed: 11/15/2023]
Abstract
An enhanced understanding of neurotransmitter systems contributing to pain transmission aids in drug development, while the identification of biological variables like age and sex helps in the development of personalized pain management and effective clinical trial design. This study identified enhanced expression of purinergic signaling components specifically in painful inflammation, with levels increased more in women as compared to men. Inflammatory dental pain is common and potentially debilitating; as inflammation of the dental pulp can occur with or without pain, it provides a powerful model to examine distinct pain pathways in humans. In control tissues, P2X3 and P2X2 receptors colocalized with PGP9.5-positive nerves. Expression of the ecto-nucleotidase NTPDase1 (CD39) increased with exposure to extracellular adenosine triphosphate (ATP), implying CD39 acted as a marker for sustained elevation of extracellular ATP. Both immunohistochemistry and immunoblots showed P2X2, P2X3, and CD39 increased in symptomatic pulpitis, suggesting receptors and the ATP agonist were elevated in patients with increased pain. The increased expression of P2X3 and CD39 was more frequently observed in women than men. In summary, this study identifies CD39 as a marker for chronic elevation of extracellular ATP in fixed human tissue. It supports a role for increased purinergic signaling in humans with inflammatory dental pain and suggests the contribution of purines shows sexual dimorphism. This highlights the potential for P2X antagonists to treat pain in humans and stresses the need to consider sex in clinical trials that target pain and purinergic pathways. PERSPECTIVE: This article demonstrates an elevation of ATP-marker CD39 and of ATP receptors P2X2 and P2X3 with inflammatory pain and suggests the rise is greater in women. This highlights the potential for P2X antagonists to treat pain and stresses the consideration of sexual dimorphism in studies of purines and pain.
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Affiliation(s)
- Lily P. See
- Departments of Basic and Translational Science, University of Pennsylvania, Philadelphia, PA 19104
- Department of Endodontics, University of Pennsylvania, Philadelphia, PA 19104
| | - Puttipong Sripinun
- Departments of Basic and Translational Science, University of Pennsylvania, Philadelphia, PA 19104
- Department of Orthodontics, University of Pennsylvania, Philadelphia, PA 19104
| | - Wennan Lu
- Departments of Basic and Translational Science, University of Pennsylvania, Philadelphia, PA 19104
| | - Jiaqi Li
- Departments of Basic and Translational Science, University of Pennsylvania, Philadelphia, PA 19104
| | - Naela Alboloushi
- Department of Endodontics, University of Pennsylvania, Philadelphia, PA 19104
- Department of Oral Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | | | - Su-Min Lee
- Department of Endodontics, University of Pennsylvania, Philadelphia, PA 19104
| | - Bekir Karabucak
- Department of Endodontics, University of Pennsylvania, Philadelphia, PA 19104
| | - Steven Wang
- Department of Oral Surgery, University of Pennsylvania, Philadelphia, PA 19104
| | | | - Katherine N. Theken
- Department of Oral Surgery, University of Pennsylvania, Philadelphia, PA 19104
| | - Claire H. Mitchell
- Departments of Basic and Translational Science, University of Pennsylvania, Philadelphia, PA 19104
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104
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Huo M, Zhang Q, Si Y, Zhang Y, Chang H, Zhou M, Zhang D, Fang Y. The role of purinergic signaling in acupuncture-mediated relief of neuropathic and inflammatory pain. Purinergic Signal 2024:10.1007/s11302-024-09985-y. [PMID: 38305986 DOI: 10.1007/s11302-024-09985-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 01/05/2024] [Indexed: 02/03/2024] Open
Abstract
Acupuncture is a traditional medicinal practice in China that has been increasingly recognized in other countries in recent decades. Notably, several reports have demonstrated that acupuncture can effectively aid in pain management. However, the analgesic mechanisms through which acupuncture provides such benefits remain poorly understood. Purinergic signaling, which is mediated by purine nucleotides and purinergic receptors, has been proposed to play a central role in acupuncture analgesia. On the one hand, acupuncture affects the transmission of nociception by increasing adenosine triphosphate dephosphorylation and thereby decreasing downstream P2X3, P2X4, and P2X7 receptors signaling activity, regulating the levels of inflammatory factors, neurotrophic factors, and synapsin I. On the other hand, acupuncture exerts analgesic effects by promoting the production of adenosine, enhancing the expression of downstream adenosine A1 and A2A receptors, and regulating downstream inflammatory factors or synaptic plasticity. Together, this systematic overview of the field provides a sound, evidence-based foundation for future research focused on the application of acupuncture as a means of relieving pain.
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Affiliation(s)
- Mingzhu Huo
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China
| | - Qingxiang Zhang
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China
| | - Yuxin Si
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China
| | - Youlin Zhang
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China
| | - Hongen Chang
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China
| | - Mengmeng Zhou
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China
| | - Di Zhang
- College of Pharmaceutical Engineering of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China.
- State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China.
- Haihe Laboratory of Modern Chinese, Tianjin, 301617, People's Republic of China.
| | - Yuxin Fang
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China.
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Zhang Q, Zhou M, Huo M, Si Y, Zhang Y, Fang Y, Zhang D. Mechanisms of acupuncture-electroacupuncture on inflammatory pain. Mol Pain 2023; 19:17448069231202882. [PMID: 37678839 PMCID: PMC10515556 DOI: 10.1177/17448069231202882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 09/06/2023] [Indexed: 09/09/2023] Open
Abstract
Acupuncture, as a traditional treatment, has been extensively used in China for thousands of years. According to the World Health Organization (WHO), acupuncture is recommended for the treatment of 77 diseases. And 16 of these diseases are related to inflammatory pain. As a combination of traditional acupuncture and modern electrotherapy, electroacupuncture (EA) has satisfactory analgesic effects on various acute and chronic pain. Because of its good analgesic effects and no side effects, acupuncture has been widely accepted all over the world. Despite the increase in the number of studies, the mechanisms via which acupuncture exerts its analgesic effects have not been conclusively established. A literature review of related research is of great significance to elaborate on its mechanisms and to inform on further research directions. We elucidated on its mechanisms of action on inflammatory pain from two levels: peripheral and central. It includes the mechanisms of acupuncture in the periphery (immune cells and neurons, purinergic pathway, nociceptive ion channel, cannabinoid receptor and endogenous opioid peptide system) and central nervous system (TPRV1, glutamate and its receptors, glial cells, GABAergic interneurons and signaling molecules). In this review, we collected relevant recent studies to systematically explain the mechanisms of acupuncture in treating inflammatory pain, with a view to providing direction for future applications of acupuncture in inflammatory pain and promoting clinical development.
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Affiliation(s)
- Qingxiang Zhang
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Mengmeng Zhou
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Mingzhu Huo
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Yuxin Si
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Youlin Zhang
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Yuxin Fang
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Di Zhang
- College of Pharmaceutical Engineering of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- Haihe Laboratory of Modern Chinese Medicine, Tianjin, China
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Ohyama S, Ouchi T, Kimura M, Kurashima R, Yasumatsu K, Nishida D, Hitomi S, Ubaidus S, Kuroda H, Ito S, Takano M, Ono K, Mizoguchi T, Katakura A, Shibukawa Y. Piezo1-pannexin-1-P2X 3 axis in odontoblasts and neurons mediates sensory transduction in dentinal sensitivity. Front Physiol 2022; 13:891759. [PMID: 36589456 PMCID: PMC9795215 DOI: 10.3389/fphys.2022.891759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 11/22/2022] [Indexed: 12/15/2022] Open
Abstract
According to the "hydrodynamic theory," dentinal pain or sensitivity is caused by dentinal fluid movement following the application of various stimuli to the dentin surface. Recent convergent evidence in Vitro has shown that plasma membrane deformation, mimicking dentinal fluid movement, activates mechanosensitive transient receptor potential (TRP)/Piezo channels in odontoblasts, with the Ca2+ signal eliciting the release of ATP from pannexin-1 (PANX-1). The released ATP activates the P2X3 receptor, which generates and propagates action potentials in the intradental Aδ afferent neurons. Thus, odontoblasts act as sensory receptor cells, and odontoblast-neuron signal communication established by the TRP/Piezo channel-PANX-1-P2X3 receptor complex may describe the mechanism of the sensory transduction sequence for dentinal sensitivity. To determine whether odontoblast-neuron communication and odontoblasts acting as sensory receptors are essential for generating dentinal pain, we evaluated nociceptive scores by analyzing behaviors evoked by dentinal sensitivity in conscious Wistar rats and Cre-mediated transgenic mouse models. In the dentin-exposed group, treatment with a bonding agent on the dentin surface, as well as systemic administration of A-317491 (P2X3 receptor antagonist), mefloquine and 10PANX (non-selective and selective PANX-1 antagonists), GsMTx-4 (selective Piezo1 channel antagonist), and HC-030031 (selective TRPA1 channel antagonist), but not HC-070 (selective TRPC5 channel antagonist), significantly reduced nociceptive scores following cold water (0.1 ml) stimulation of the exposed dentin surface of the incisors compared to the scores of rats without local or systemic treatment. When we applied cold water stimulation to the exposed dentin surface of the lower first molar, nociceptive scores in the rats with systemic administration of A-317491, 10PANX, and GsMTx-4 were significantly reduced compared to those in the rats without systemic treatment. Dentin-exposed mice, with somatic odontoblast-specific depletion, also showed significant reduction in the nociceptive scores compared to those of Cre-mediated transgenic mice, which did not show any type of cell deletion, including odontoblasts. In the odontoblast-eliminated mice, P2X3 receptor-positive A-neurons were morphologically intact. These results indicate that neurotransmission between odontoblasts and neurons mediated by the Piezo1/TRPA1-pannexin-1-P2X3 receptor axis is necessary for the development of dentinal pain. In addition, odontoblasts are necessary for sensory transduction to generate dentinal sensitivity as mechanosensory receptor cells.
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Affiliation(s)
- Sadao Ohyama
- Department of Physiology, Tokyo Dental College, Tokyo, Japan,Oral Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, Tokyo, Japan
| | - Takehito Ouchi
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Maki Kimura
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Ryuya Kurashima
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | | | - Daisuke Nishida
- Oral Health Science Center, Tokyo Dental College, Tokyo, Japan
| | - Suzuro Hitomi
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan,Division of Physiology, Kyushu Dental University, Fukuoka, Japan
| | - Sobhan Ubaidus
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Hidetaka Kuroda
- Department of Physiology, Tokyo Dental College, Tokyo, Japan,Department of Dental Anesthesiology, Kanagawa Dental University, Yokosuka, Japan
| | - Shinichirou Ito
- Department of Oral and Maxillofacial Surgery, Tokyo Dental College, Tokyo, Japan
| | - Masayuki Takano
- Department of Oral and Maxillofacial Surgery, Tokyo Dental College, Tokyo, Japan
| | - Kentaro Ono
- Division of Physiology, Kyushu Dental University, Fukuoka, Japan
| | | | - Akira Katakura
- Department of Oral Pathological Science and Surgery, Tokyo Dental College, Tokyo, Japan
| | - Yoshiyuki Shibukawa
- Department of Physiology, Tokyo Dental College, Tokyo, Japan,*Correspondence: Yoshiyuki Shibukawa,
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Inoue H, Kuroda H, Ofusa W, Oyama S, Kimura M, Ichinohe T, Shibukawa Y. Functional Coupling between the P2X 7 Receptor and Pannexin-1 Channel in Rat Trigeminal Ganglion Neurons. Int J Mol Sci 2021; 22:ijms22115978. [PMID: 34205953 PMCID: PMC8198496 DOI: 10.3390/ijms22115978] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/19/2021] [Accepted: 05/27/2021] [Indexed: 11/16/2022] Open
Abstract
The ionotropic P2X receptor, P2X7, is believed to regulate and/or generate nociceptive pain, and pain in several neuropathological diseases. Although there is a known relationship between P2X7 receptor activity and pain sensing, its detailed functional properties in trigeminal ganglion (TG) neurons remains unclear. We examined the electrophysiological and pharmacological characteristics of the P2X7 receptor and its functional coupling with other P2X receptors and pannexin-1 (PANX1) channels in primary cultured rat TG neurons, using whole-cell patch-clamp recordings. Application of ATP and Bz-ATP induced long-lasting biphasic inward currents that were more sensitive to extracellular Bz-ATP than ATP, indicating that the current was carried by P2X7 receptors. While the biphasic current densities of the first and second components were increased by Bz-ATP in a concentration dependent manner; current duration was only affected in the second component. These currents were significantly inhibited by P2X7 receptor antagonists, while only the second component was inhibited by P2X1, 3, and 4 receptor antagonists, PANX1 channel inhibitors, and extracellular ATPase. Taken together, our data suggests that autocrine or paracrine signaling via the P2X7-PANX1-P2X receptor/channel complex may play important roles in several pain sensing pathways via long-lasting neuronal activity driven by extracellular high-concentration ATP following tissue damage in the orofacial area.
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Affiliation(s)
- Hiroyuki Inoue
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
- Department of Dental Anesthesiology, Tokyo Dental College, Tokyo 101-0061, Japan;
| | - Hidetaka Kuroda
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
- Department of Dental Anesthesiology, Kanagawa Dental University, Kanagawa 238-8580, Japan
| | - Wataru Ofusa
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
| | - Sadao Oyama
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
| | - Maki Kimura
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
| | - Tatsuya Ichinohe
- Department of Dental Anesthesiology, Tokyo Dental College, Tokyo 101-0061, Japan;
| | - Yoshiyuki Shibukawa
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
- Correspondence:
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Nango H, Kosuge Y, Sato M, Shibukawa Y, Aono Y, Saigusa T, Ito Y, Ishige K. Highly Efficient Conversion of Motor Neuron-Like NSC-34 Cells into Functional Motor Neurons by Prostaglandin E 2. Cells 2020; 9:cells9071741. [PMID: 32708195 PMCID: PMC7409148 DOI: 10.3390/cells9071741] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 07/10/2020] [Accepted: 07/20/2020] [Indexed: 12/19/2022] Open
Abstract
Motor neuron diseases are a group of progressive neurological disorders that degenerate motor neurons. The neuroblastoma × spinal cord hybrid cell line NSC-34 is widely used as an experimental model in studies of motor neuron diseases. However, the differentiation efficiency of NSC-34 cells to neurons is not always sufficient. We have found that prostaglandin E2 (PGE2) induces morphological differentiation in NSC-34 cells. The present study investigated the functional properties of PGE2-differentiated NSC-34 cells. Retinoic acid (RA), a widely-used agent inducing cell differentiation, facilitated neuritogenesis, which peaked on day 7, whereas PGE2-induced neuritogenesis took only 2 days to reach the same level. Whole-cell patch-clamp recordings showed that the current threshold of PGE2-treated cell action potentials was lower than that of RA-treated cells. PGE2 and RA increased the protein expression levels of neuronal differentiation markers, microtubule-associated protein 2c and synaptophysin, and to the same extent, motor neuron-specific markers HB9 and Islet-1. On the other hand, protein levels of choline acetyltransferase and basal release of acetylcholine in PGE2-treated cells were higher than in RA-treated cells. These results suggest that PGE2 is a rapid and efficient differentiation-inducing factor for the preparation of functionally mature motor neurons from NSC-34 cells.
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Affiliation(s)
- Hiroshi Nango
- Laboratory of Pharmacology, School of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi-shi, Chiba 274-8555, Japan; (H.N.); (Y.I.)
| | - Yasuhiro Kosuge
- Laboratory of Pharmacology, School of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi-shi, Chiba 274-8555, Japan; (H.N.); (Y.I.)
- Correspondence: (Y.K.); (K.I.); Tel.: +81-47-465-4027 (Y.K.)
| | - Masaki Sato
- Department of Physiology, Tokyo Dental College, 2-9-18 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan; (M.S.); (Y.S.)
- Department of Biology Tokyo Dental College, 2-9-7 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan
| | - Yoshiyuki Shibukawa
- Department of Physiology, Tokyo Dental College, 2-9-18 Kanda-Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan; (M.S.); (Y.S.)
| | - Yuri Aono
- Department of Pharmacology, School of Dentistry at Matsudo, Nihon University, 2-870-1 Sakaechonishi, Matsudo-shi, Chiba 271-8587, Japan; (Y.A.); (T.S.)
| | - Tadashi Saigusa
- Department of Pharmacology, School of Dentistry at Matsudo, Nihon University, 2-870-1 Sakaechonishi, Matsudo-shi, Chiba 271-8587, Japan; (Y.A.); (T.S.)
| | - Yoshihisa Ito
- Laboratory of Pharmacology, School of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi-shi, Chiba 274-8555, Japan; (H.N.); (Y.I.)
- Pharmacy Education Center, Yokohama University of Pharmacy, 601 Matanocho, Totuka-ku, Yokohama 245-0066, Japan
| | - Kumiko Ishige
- Laboratory of Pharmacology, School of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi-shi, Chiba 274-8555, Japan; (H.N.); (Y.I.)
- Correspondence: (Y.K.); (K.I.); Tel.: +81-47-465-4027 (Y.K.)
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Electroacupuncture Stimulation Alleviates CFA-Induced Inflammatory Pain Via Suppressing P2X3 Expression. Int J Mol Sci 2019; 20:ijms20133248. [PMID: 31269659 PMCID: PMC6651287 DOI: 10.3390/ijms20133248] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 06/25/2019] [Accepted: 06/28/2019] [Indexed: 12/13/2022] Open
Abstract
Chronic inflammatory pain is one of the most common complaints that seriously affects patients’ quality of life. Previous studies have demonstrated that the analgesic effect of electroacupuncture (EA) stimulation on inflammatory pain is related to its frequency. In this study, we focused on whether the analgesic effects of EA are related to the period of stimulation. Purinergic receptor P2X3 (P2X3) is involved in the pathological process underlying chronic inflammatory pain and neuropathic pain. We hypothesized that 100 Hz EA stimulation alleviated Freund’s complete adjuvant (CFA) induced inflammatory pain via regulating P2X3 expression in the dorsal root ganglion (DRG) and/or spinal cord dorsal horn (SCDH). We also assumed that the analgesic effect of EA might be related to the period of stimulation. We found that both short-term (three day) and long-term (14 day) 100 Hz EA stimulation effectively increased the paw withdrawal threshold (PWT) and reversed the elevation of P2X3 in the DRG and SCDH of CFA rats. However, the analgesic effects of 100 Hz EA were not dependent on the period of stimulation. Moreover, P2X3 inhibition or activation may contribute to or attenuate the analgesic effects of 100 Hz EA on CFA-induced inflammatory pain. This result indicated that EA reduced pain hypersensitivity through P2X3 modulation.
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Lee K, Lee BM, Park CK, Kim YH, Chung G. Ion Channels Involved in Tooth Pain. Int J Mol Sci 2019; 20:ijms20092266. [PMID: 31071917 PMCID: PMC6539952 DOI: 10.3390/ijms20092266] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 05/03/2019] [Accepted: 05/03/2019] [Indexed: 01/05/2023] Open
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.
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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.
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Sato M, Ogura K, Kimura M, Nishi K, Ando M, Tazaki M, Shibukawa Y. Activation of Mechanosensitive Transient Receptor Potential/Piezo Channels in Odontoblasts Generates Action Potentials in Cocultured Isolectin B 4-negative Medium-sized Trigeminal Ganglion Neurons. J Endod 2018; 44:984-991.e2. [PMID: 29709295 DOI: 10.1016/j.joen.2018.02.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 02/15/2018] [Accepted: 02/20/2018] [Indexed: 01/22/2023]
Abstract
INTRODUCTION Various stimuli to the dentin surface elicit dentinal pain by inducing dentinal fluid movement causing cellular deformation in odontoblasts. Although odontoblasts detect deformation by the activation of mechanosensitive ionic channels, it is still unclear whether odontoblasts are capable of establishing neurotransmission with myelinated A delta (Aδ) neurons. Additionally, it is still unclear whether these neurons evoke action potentials by neurotransmitters from odontoblasts to mediate sensory transduction in dentin. Thus, we investigated evoked inward currents and evoked action potentials form trigeminal ganglion (TG) neurons after odontoblast mechanical stimulation. METHODS We used patch clamp recordings to identify electrophysiological properties and record evoked responses in TG neurons. RESULTS We classified TG cells into small-sized and medium-sized neurons. In both types of neurons, we observed voltage-dependent inward currents. The currents from medium-sized neurons showed fast inactivation kinetics. When mechanical stimuli were applied to odontoblasts, evoked inward currents were recorded from medium-sized neurons. Antagonists for the ionotropic adenosine triphosphate receptor (P2X3), transient receptor potential channel subfamilies, and Piezo1 channel significantly inhibited these inward currents. Mechanical stimulation to odontoblasts also generated action potentials in the isolectin B4-negative medium-sized neurons. Action potentials in these isolectin B4-negative medium-sized neurons showed a short duration. Overall, electrophysiological properties of neurons indicate that the TG neurons with recorded evoked responses after odontoblast mechanical stimulation were myelinated Aδ neurons. CONCLUSIONS Odontoblasts established neurotransmission with myelinated Aδ neurons via P2X3 receptor activation. The results also indicated that mechanosensitive TRP/Piezo1 channels were functionally expressed in odontoblasts. The activation of P2X3 receptors induced an action potential in the Aδ neurons, underlying a sensory generation mechanism of dentinal pain.
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Affiliation(s)
- Masaki Sato
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Kazuhiro Ogura
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Maki Kimura
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Koichi Nishi
- Removable Prosthodontics and Gerodontology, Tokyo Dental College, Tokyo, Japan
| | - Masayuki Ando
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Masakazu Tazaki
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
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Kojima Y, Kimura M, Higashikawa A, Kono K, Ando M, Tazaki M, Shibukawa Y. Potassium Currents Activated by Depolarization in Odontoblasts. Front Physiol 2017; 8:1078. [PMID: 29311993 PMCID: PMC5742198 DOI: 10.3389/fphys.2017.01078] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 12/06/2017] [Indexed: 12/30/2022] Open
Abstract
Increased intracellular free Ca2+ concentrations elicit plasma membrane depolarization, which leads to the activation of K+ currents. However, the precise properties of K+ currents activated by depolarization in odontoblasts remain to be elucidated. The present study identified biophysical and pharmacological characteristics of time-dependent and voltage-activated K+ currents in freshly dissociated rat odontoblasts using patch-clamp recordings in a whole-cell configuration. Using a holding potential of −70 mV, outwardly rectifying time- and voltage-dependent currents were activated by depolarizing voltage. To record pure K+ conductance, we substituted Cl− in both the extracellular and intracellular solutions with gluconate−. Under these conditions, observation of K+ concentration changes in the extracellular solution showed that reversal potentials of tail currents shifted according to the K+ equilibrium potential. The activation kinetics of outward K+ currents were relatively slow and depended on the membrane potential. Kinetics of steady-state inactivation were fitted by a Boltzmann function. The half-maximal inactivation potential was −38 mV. Tetraethylammonium chloride, 4-aminopyridine, and α-dendrotoxin inhibited outward currents in odontoblasts in a concentration-dependent manner, suggesting that rat odontoblasts express the α-subunit of the time- and voltage-dependent K+ channel (Kv) subtypes Kv1.1, 1.2, and/or 1.6. We further examined the effects of Kv activity on mineralization by alizarin red and von Kossa staining. Continuous application of tetraethylammonium chloride to human odontoblasts grown in a mineralization medium over a 21-day period exhibited a dose-dependent decrease in mineralization efficiency compared to cells without tetraethylammonium chloride. This suggests that odontoblasts functionally express voltage-dependent K+ channels that play important roles in dentin formation.
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Affiliation(s)
- Yuki Kojima
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Maki Kimura
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | | | - Kyosuke Kono
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Masayuki Ando
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Masakzu Tazaki
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
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Solé-Magdalena A, Martínez-Alonso M, Coronado CA, Junquera LM, Cobo J, Vega JA. Molecular basis of dental sensitivity: The odontoblasts are multisensory cells and express multifunctional ion channels. Ann Anat 2017; 215:20-29. [PMID: 28954208 DOI: 10.1016/j.aanat.2017.09.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 08/22/2017] [Accepted: 09/10/2017] [Indexed: 12/26/2022]
Abstract
Odontoblasts are the dental pulp cells responsible for the formation of dentin. In addition, accumulating data strongly suggest that they can also function as sensory cells that mediate the early steps of mechanical, thermic, and chemical dental sensitivity. This assumption is based on the expression of different families of ion channels involved in various modalities of sensitivity and the release of putative neurotransmitters in response to odontoblast stimulation which are able to act on pulp sensory nerve fibers. This review updates the current knowledge on the expression of transient-potential receptor ion channels and acid-sensing ion channels in odontoblasts, nerve fibers innervating them and trigeminal sensory neurons, as well as in pulp cells. Moreover, the innervation of the odontoblasts and the interrelationship been odontoblasts and nerve fibers mediated by neurotransmitters was also revisited. These data might provide the basis for novel therapeutic approaches for the treatment of dentin sensibility and/or dental pain.
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Affiliation(s)
- A Solé-Magdalena
- Departamento de Morfología y Biología Celular Universidad de Oviedo, Spain
| | - M Martínez-Alonso
- Departamento de Morfología y Biología Celular Universidad de Oviedo, Spain
| | - C A Coronado
- Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Temuco, Chile
| | - L M Junquera
- Departamento de Especialidades Médico-Quirúrgicas, Universidad de Oviedo, Spain; Servicio de Cirugía Maxilofacial, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - J Cobo
- Departamento de Especialidades Médico-Quirúrgicas, Universidad de Oviedo, Spain; Instituto Asturiano de Odontología, Oviedo, Spain
| | - J A Vega
- Departamento de Morfología y Biología Celular Universidad de Oviedo, Spain; Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Temuco, Chile.
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Abstract
The P2X7 receptor is a trimeric ion channel gated by extracellular adenosine 5'-triphosphate. The receptor is present on an increasing number of different cells types including stem, blood, glial, neural, ocular, bone, dental, exocrine, endothelial, muscle, renal and skin cells. The P2X7 receptor induces various downstream events in a cell-specific manner, including inflammatory molecule release, cell proliferation and death, metabolic events, and phagocytosis. As such this receptor plays important roles in heath and disease. Increasing knowledge about the P2X7 receptor has been gained from studies of, but not limited to, protein chemistry including cloning, site-directed mutagenesis, crystal structures and atomic modeling, as well as from studies of primary tissues and transgenic mice. This chapter focuses on the P2X7 receptor itself. This includes the P2RX7 gene and its products including splice and polymorphic variants. This chapter also reviews modulators of P2X7 receptor activation and inhibition, as well as the transcriptional regulation of the P2RX7 gene via its promoter and enhancer regions, and by microRNA and long-coding RNA. Furthermore, this chapter discusses the post-translational modification of the P2X7 receptor by N-linked glycosylation, adenosine 5'-diphosphate ribosylation and palmitoylation. Finally, this chapter reviews interaction partners of the P2X7 receptor, and its cellular localisation and trafficking within cells.
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Affiliation(s)
- Ronald Sluyter
- School of Biological Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
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