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Wang Z, Ma H, Nasir A, Liu S, Li Z, Tao F, Bai Q. TET1-mediated epigenetic regulation of tumor necrosis factor-α in trigeminal ganglia contributes to chronic temporomandibular joint pain. Life Sci 2024; 336:122283. [PMID: 37993094 DOI: 10.1016/j.lfs.2023.122283] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/15/2023] [Accepted: 11/19/2023] [Indexed: 11/24/2023]
Abstract
Chronic temporomandibular joint (TMJ) pain profoundly affects patients' quality of life. Trigeminal tumor necrosis factor-α (TNFα) plays a pivotal role in mediating TMJ pain in mice, yet the underlying epigenetic mechanisms remain enigmatic. To unravel these epigenetic intricacies, we employed a multifaceted approach. Hydroxymethylated DNA immunoprecipitation (hMeDIP) and chromatin immunoprecipitation (ChIP) followed by qPCR were employed to investigate the demethylation of TNFα gene (Tnfa) and its regulation by ten-eleven translocation methylcytosine dioxygenase 1 (TET1) in a chronic TMJ pain mouse model. The global levels of 5-hydroxymethylcytosine (5hmc) and percentage of 5hmc at the Tnfa promoter region were measured in the trigeminal ganglia (TG) and spinal trigeminal nucleus caudalis (Sp5C) following complete Freund's adjuvant (CFA) or saline treatment. TET1 knockdown and pain behavioral testing were conducted to ascertain the role of TET1-mediated epigenetic regulation of TNFα in the pathogenesis of chronic TMJ pain. Our finding revealed an increase in 5hmc at the Tnfa promoter region in both TG and Sp5C of CFA-treated mice. TET1 was upregulated in the mouse TG, and the ChIP result showed TET1 direct binding to the Tnfa promoter, with higher efficiency in the CFA-treated group. Immunofluorescence revealed the predominant expression of TET1 in trigeminal neurons. TET1 knockdown in the TG significantly reversed CFA-induced TNFα upregulation and alleviated chronic TMJ pain. In conclusion, our study implicates TET1 as a vital epigenetic regulator contributing to chronic inflammatory TMJ pain via trigeminal TNFα signaling. Targeting TET1 holds promise for epigenetic interventions in TMJ pain management.
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Affiliation(s)
- Zhitao Wang
- Department of Anesthesiology and Perioperative Medicine, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Heng Ma
- Department of Anesthesiology and Perioperative Medicine, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Abdul Nasir
- Department of Anesthesiology and Perioperative Medicine, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China; Medical Research Center, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Sufang Liu
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, TX, USA
| | - Zhisong Li
- Department of Anesthesiology and Perioperative Medicine, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Feng Tao
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, TX, USA.
| | - Qian Bai
- Department of Anesthesiology and Perioperative Medicine, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China; Medical Research Center, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.
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Youn DH, Weon H. Endogenous TRPC channels mediate Ca 2+ signals and trigeminal synaptic plasticity induced by mGluR5. Life Sci 2019; 231:116567. [PMID: 31202839 DOI: 10.1016/j.lfs.2019.116567] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 06/11/2019] [Accepted: 06/12/2019] [Indexed: 11/30/2022]
Abstract
AIMS Metabotropic glutamate receptor 5 (mGluR5), a member of group I mGluR, exerts its effect via elevation of intracellular Ca2+ level. We here characterized Ca2+ signals in the tsA201 cells transfected with mGluR5 and investigated the role of passages for mGluR5-induced Ca2+ signals in synaptic plasticity. MAIN METHODS Using a genetically encoded Ca2+ indicator, GCamp2, Ca2+ signals were reliably induced by bath application of (S)-3,5-dihydroxyphenylglycine, the group I mGluR agonist, in the tsA201 cells transfected with mGluR5. Using whole-cell recordings in the substantia gelatinosa (SG) neurons of the spinal trigeminal subnucleus caudalis (Vc), excitatory postsynaptic currents were recorded by stimulating the trigeminal tract. KEY FINDINGS Ca2+ signals were mediated by "classical" or "canonical" transient receptor potential (TRPC) channels, particularly TRPC1/3/4/6, but not TRPC5, naturally existing in the tsA201 cells. Interestingly, the induction of Ca2+ signals was independent of the phospholipase C signaling pathway; instead, it critically involves the cyclic adenosine diphosphate ribose/ryanodine receptor-dependent signaling pathway and only partially protein kinase C. On the other hand, both TRPC3 and TRPC4 mediated mGluR1/5-induced long-lasting potentiation of excitatory synaptic transmission from the trigeminal primary afferents to the SG neurons of the Vc. SIGNIFICANCE This study demonstrates that endogenous TRPC channels contribute to mGluR5-induced Ca2+ signals in tsA201 cells and synaptic plasticity at excitatory synapses.
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Affiliation(s)
- Dong-Ho Youn
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, 2177, Dalgubeol-daero, Jung-gu, Daegu, 41940, Republic of Korea.
| | - Haein Weon
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, 2177, Dalgubeol-daero, Jung-gu, Daegu, 41940, Republic of Korea
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Tang Y, Liu S, Shu H, Yanagisawa L, Tao F. Gut Microbiota Dysbiosis Enhances Migraine-Like Pain Via TNFα Upregulation. Mol Neurobiol 2020; 57:461-8. [PMID: 31378003 DOI: 10.1007/s12035-019-01721-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 07/26/2019] [Indexed: 12/12/2022]
Abstract
Migraine is one of the most disabling neurological diseases worldwide; however, the mechanisms underlying migraine headache are still not fully understood and current therapies for such pain are inadequate. It has been suggested that inflammation and neuroimmune modulation in the gastrointestinal tract could play an important role in the pathogenesis of migraine headache, but how gut microbiomes contribute to migraine headache is unclear. In the present study, we investigated the effect of gut microbiota dysbiosis on migraine-like pain using broad-spectrum antibiotics and germ-free (GF) mice. We observed that antibiotics treatment-prolonged nitroglycerin (NTG)-induced acute migraine-like pain in wild-type (WT) mice and the pain prolongation was completely blocked by genetic deletion of tumor necrosis factor-alpha (TNFα) or intra-spinal trigeminal nucleus caudalis (Sp5C) injection of TNFα receptor antagonist. The antibiotics treatment extended NTG-induced TNFα upregulation in the Sp5C. Probiotics administration significantly inhibited the antibiotics-produced migraine-like pain prolongation. Furthermore, NTG-induced migraine-like pain in GF mice was markedly enhanced compared to that in WT mice and gut colonization with fecal microbiota from WT mice robustly reversed microbiota deprivation-caused pain enhancement. Together, our results suggest that gut microbiota dysbiosis contributes to chronicity of migraine-like pain by upregulating TNFα level in the trigeminal nociceptive system.
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Uddin O, Studlack PE, Parihar S, Keledjian K, Cruz A, Farooq T, Shin N, Gerzanich V, Simard JM, Keller A. Chronic pain after blast-induced traumatic brain injury in awake rats. Neurobiol Pain 2019; 6:100030. [PMID: 31223145 PMCID: PMC6565615 DOI: 10.1016/j.ynpai.2019.100030] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 02/14/2019] [Accepted: 04/01/2019] [Indexed: 12/14/2022]
Abstract
Explosive blast-induced traumatic brain injury (blast-TBI) in military personnel is a leading cause of injury and persistent neurological abnormalities, including chronic pain. We previously demonstrated that chronic pain after spinal cord injury results from central sensitization in the posterior thalamus (PO). The presence of persistent headaches and back pain in veterans with blast-TBI suggests a similar involvement of thalamic sensitization. Here, we tested the hypothesis that pain after blast-TBI is associated with abnormal increases in activity of neurons in PO thalamus. We developed a novel model with two unique features: (1) blast-TBI was performed in awake, un-anesthetized rats, to simulate the human experience and to eliminate confounds of anesthesia and surgery inherent in other models; (2) only the cranium, rather than the entire body, was exposed to a collimated blast wave, with the blast wave striking the posterior cranium in the region of the occipital crest and foramen magnum. Three weeks after blast-TBI, rats developed persistent, ongoing spontaneous pain. Contrary to our hypothesis, we found no significant differences in the activity of PO neurons, or of neurons in the spinal trigeminal nucleus. There were also no significant changes in gliosis in either of these structures. This novel model will allow future studies on the pathophysiology of chronic pain after blast-TBI.
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Affiliation(s)
- Olivia Uddin
- Department of Anatomy and Neurobiology and Program in Neuroscience, University of Maryland School of Medicine, 20 Penn St, HSF-II S251, Baltimore, MD, USA
| | - Paige E Studlack
- Department of Anatomy and Neurobiology and Program in Neuroscience, University of Maryland School of Medicine, 20 Penn St, HSF-II S251, Baltimore, MD, USA
| | - Saitu Parihar
- Department of Anatomy and Neurobiology and Program in Neuroscience, University of Maryland School of Medicine, 20 Penn St, HSF-II S251, Baltimore, MD, USA
| | - Kaspar Keledjian
- Department of Neurosurgery, University of Maryland School of Medicine, 10 S Pine St, MSTF 634B, Baltimore, MD, USA
| | - Alexis Cruz
- Department of Anatomy and Neurobiology and Program in Neuroscience, University of Maryland School of Medicine, 20 Penn St, HSF-II S251, Baltimore, MD, USA
| | - Tayyiaba Farooq
- Department of Anatomy and Neurobiology and Program in Neuroscience, University of Maryland School of Medicine, 20 Penn St, HSF-II S251, Baltimore, MD, USA
| | - Naomi Shin
- Department of Anatomy and Neurobiology and Program in Neuroscience, University of Maryland School of Medicine, 20 Penn St, HSF-II S251, Baltimore, MD, USA
| | - Volodymyr Gerzanich
- Department of Neurosurgery, University of Maryland School of Medicine, 10 S Pine St, MSTF 634B, Baltimore, MD, USA
| | - J Marc Simard
- Department of Neurosurgery, University of Maryland School of Medicine, 10 S Pine St, MSTF 634B, Baltimore, MD, USA.,Department of Pathology, University of Maryland School of Medicine, 10 S Pine St, MSTF, Room 634B, Baltimore, MD, USA.,Department of Physiology, University of Maryland School of Medicine, 10 S Pine St, MSTF, Room 634B, Baltimore, MD, USA
| | - Asaf Keller
- Department of Anatomy and Neurobiology and Program in Neuroscience, University of Maryland School of Medicine, 20 Penn St, HSF-II S251, Baltimore, MD, USA
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Hidaka S, Kanai Y, Takehana S, Syoji Y, Kubota Y, Uotsu N, Yui K, Shimazu Y, Takeda M. Systemic administration of α-lipoic acid suppresses excitability of nociceptive wide-dynamic range neurons in rat spinal trigeminal nucleus caudalis. Neurosci Res 2018; 144:14-20. [PMID: 29885345 DOI: 10.1016/j.neures.2018.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/25/2018] [Accepted: 06/04/2018] [Indexed: 11/16/2022]
Abstract
Although a modulatory role has been reported for α-lipoic acid (LA) on T-type Ca2+ channels in the nervous system, the acute effects of LA in vivo, particularly on nociceptive transmission in the trigeminal system, remain to be determined. The aim of the present study was to investigate whether acute intravenous LA administration to rats attenuates the excitability of wide dynamic range (WDR) spinal trigeminal nucleus caudalis (SpVc) neurons in response to nociceptive and non-nociceptive mechanical stimulation in vivo. Extracellular single unit recordings were made from seventeen SpVc neurons in response to orofacial mechanical stimulation of pentobarbital-anesthetized rats. Responses to both non-noxious and noxious mechanical stimuli were analyzed in the present study. The mean firing frequency of SpVc WDR neurons in response to both non-noxious and noxious mechanical stimuli was significantly and dose-dependently inhibited by LA (1-100 mM, i.v.) and maximum inhibition of the discharge frequency of both non-noxious and noxious mechanical stimuli was seen within 5 min. These inhibitory effects lasted for approximately 10 min. These results suggest that acute intravenous LA administration suppresses trigeminal sensory transmission, including nociception, via possibly blocking T-type Ca2+ channels. LA may be used as a therapeutic agent for the treatment of trigeminal nociceptive pain.
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Affiliation(s)
- S Hidaka
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan
| | - Y Kanai
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan
| | - S Takehana
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan
| | - Y Syoji
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan
| | - Y Kubota
- FANCL Health Science Research Center, Research Institute, FANCL Corporation, 12-13, Kamishinano, Totsuka-ku, Yokohama, Kanagawa, 244-0806, Japan
| | - N Uotsu
- FANCL Health Science Research Center, Research Institute, FANCL Corporation, 12-13, Kamishinano, Totsuka-ku, Yokohama, Kanagawa, 244-0806, Japan
| | - K Yui
- FANCL Health Science Research Center, Research Institute, FANCL Corporation, 12-13, Kamishinano, Totsuka-ku, Yokohama, Kanagawa, 244-0806, Japan
| | - Y Shimazu
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan
| | - M Takeda
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan.
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Bai Q, Liu S, Shu H, Tang Y, George S, Dong T, Schmidt BL, Tao F. TNFα in the Trigeminal Nociceptive System Is Critical for Temporomandibular Joint Pain. Mol Neurobiol 2018; 56:278-291. [PMID: 29696511 DOI: 10.1007/s12035-018-1076-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [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: 01/03/2018] [Accepted: 04/10/2018] [Indexed: 12/30/2022]
Abstract
Previous studies have shown that tumor necrosis factor alpha (TNFα) is significantly increased in complete Freund's adjuvant (CFA)-treated temporomandibular joint (TMJ) tissues. However, it is unclear whether TNFα in the trigeminal nociceptive system contributes to the development of TMJ pain. In the present study, we investigated the role of TNFα in trigeminal ganglia (TG) and spinal trigeminal nucleus caudalis (Sp5C) in CFA-induced inflammatory TMJ pain. Intra-TMJ injection of CFA (10 μl, 5 mg/ml) induced inflammatory pain in the trigeminal nerve V2- and V3-innervated skin areas of WT mice, which was present on day 1 after CFA and persisted for at least 10 days. TNFα in both TG and Sp5C of WT mice was upregulated after CFA injection. The CFA-induced TMJ pain was significantly inhibited in TNFα KO mice. The immunofluorescence staining showed that intra-TMJ CFA injection not only enhanced co-localization of TNFα with Iba1 (a marker for microglia) in both TG and Sp5C but also markedly increased the expression of TNFα in the Sp5C neurons. By the methylated DNA immunoprecipitation assay, we also found that DNA methylation at the TNF gene promoter region in the TG was dramatically diminished after CFA injection, indicating that epigenetic regulation may be involved in the CFA-enhanced TNFα expression in our model. Our results suggest that TNFα in the trigeminal nociceptive system plays a critical role in CFA-induced inflammatory TMJ pain.
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Affiliation(s)
- Qian Bai
- Department of Anesthesiology, The Second Affiliated Hospital at Zhengzhou University School of Medicine, 2 Jingba Rd, Zhengzhou, 450000, Henan, China.,Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
| | - Sufang Liu
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA.,Department of Physiology and Neurobiology, Zhengzhou University School of Medicine, Zhengzhou, Henan, China
| | - Hui Shu
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
| | - Yuanyuan Tang
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA.,School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan, China
| | - Sanjeeth George
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
| | - Tieli Dong
- Department of Anesthesiology, The Second Affiliated Hospital at Zhengzhou University School of Medicine, 2 Jingba Rd, Zhengzhou, 450000, Henan, China.
| | - Brian L Schmidt
- Bluestone Center for Clinical Research, New York University, New York, NY, USA
| | - Feng Tao
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA. .,Center for Craniofacial Research and Diagnosis, Texas A&M University College of Dentistry, 3302 Gaston Ave, Dallas, TX, 75246, USA.
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Tang Y, Liu S, Shu H, Xing Y, Tao F. AMPA receptor GluA1 Ser831 phosphorylation is critical for nitroglycerin-induced migraine-like pain. Neuropharmacology 2018; 133:462-469. [PMID: 29486167 DOI: 10.1016/j.neuropharm.2018.02.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [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: 10/24/2017] [Revised: 02/13/2018] [Accepted: 02/23/2018] [Indexed: 12/13/2022]
Abstract
Migraine is the third most common disease worldwide; however, the mechanisms underlying migraine headache are still not fully understood. Previous studies have demonstrated that α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor phosphorylation plays an important role in central sensitization of pain transmission. In the present study, we observed that AMPA receptor GluA1 Ser831 phosphorylation was enhanced in the spinal trigeminal nucleus caudalis (Sp5C) after intraperitoneal injection of nitroglycerin (NTG). The NTG injection induced acute migraine-like pain including photophobia and mechanical hypersensitivity as reported previously. Interestingly, targeted mutation of GluA1 Ser831 site to prevent phosphorylation significantly inhibited NTG-induced migraine-like pain. Moreover, NTG incubation caused a robust Ca2+ influx in cultured brainstem neurons, which was dramatically inhibited by GluA1 S831A (serine at the 831 site of GluA1 is mutated to alanine) phospho-deficient mutation, and treatment with 1-naphthyl acetyl spermine (NASPM), a selective Ca2+-permeable AMPA receptor channel blocker, dose-dependently blocked the NTG-evoked increase of Ca2+ influx in the cultured neurons. We further found that intra-Sp5C injection of NASPM significantly inhibited NTG-produced mechanical hypersensitivity. These results suggest that AMPA receptor phosphorylation at the Ser831 site in the Sp5C is critical for NTG-induced migraine-like pain.
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Affiliation(s)
- Yuanyuan Tang
- Department of Physiology and Neurobiology, Zhengzhou University School of Medicine, Zhengzhou, Henan, China; Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, TX, USA; School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan, China
| | - Sufang Liu
- Department of Physiology and Neurobiology, Zhengzhou University School of Medicine, Zhengzhou, Henan, China; Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, TX, USA
| | - Hui Shu
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, TX, USA
| | - Ying Xing
- Department of Physiology and Neurobiology, Zhengzhou University School of Medicine, Zhengzhou, Henan, China.
| | - Feng Tao
- Department of Physiology and Neurobiology, Zhengzhou University School of Medicine, Zhengzhou, Henan, China; Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, TX, USA; Center for Craniofacial Research and Diagnosis, Texas A&M University College of Dentistry, Dallas, TX, USA.
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Takehana S, Kubota Y, Uotsu N, Yui K, Shimazu Y, Takeda M. Acute intravenous administration of dietary constituent theanine suppresses noxious neuronal transmission of trigeminal spinal nucleus caudalis in rats. Brain Res Bull 2017; 131:70-77. [PMID: 28315395 DOI: 10.1016/j.brainresbull.2017.03.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [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: 10/18/2016] [Revised: 02/08/2017] [Accepted: 03/09/2017] [Indexed: 11/16/2022]
Abstract
Theanine is a non-dietary amino acid linked to the modulation of synaptic transmission in the central nervous system, although the acute effects of theanine in vivo, particularly on nociceptive transmission in the trigeminal system, remain to be determined. The present study investigated whether acute intravenous theanine administration to rats attenuates the excitability of wide dynamic range (WDR) spinal trigeminal nucleus caudalis (SpVc) neurons in response to nociceptive and non-nociceptive mechanical stimulation in vivo. Extracellular single unit recordings were made from 15 SpVc neurons in response to orofacial mechanical stimulation of pentobarbital-anesthetized rats, and responses to non-noxious and noxious mechanical stimuli were analyzed. The mean firing frequency of SpVc WDR neurons in response to all mechanical stimuli was dose-dependently inhibited by theanine (10, 50, and 100mM, i.v.) with the maximum inhibition of discharge frequency reached within 5min. These inhibitory effects were reversed after approximately 10min. The relative magnitude of theanine's inhibition of SpVc WDR neuronal discharge frequency was significantly greater for noxious than non-noxious stimulation. Iontophoretic application of l-glutamate induced the mean firing frequency of SpVc WDR neuron responding to noxious mechanical stimulation was also inhibited by intravenous administration of 100mM theanine. These results suggest that acute intravenous theanine administration suppresses glutaminergic noxious synaptic transmission in the SpVc, implicating theanine as a potential complementary and alternative therapeutic agent for the treatment of trigeminal nociceptive pain.
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Affiliation(s)
- Shiori Takehana
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan
| | - Yoshiko Kubota
- FANCL Health Science Research Center, Research Institute, FANCL Corporation, 12-13, Kamishinano, Totsuka-ku, Yokohama, Kanagawa, 244-0806, Japan
| | - Nobuo Uotsu
- FANCL Health Science Research Center, Research Institute, FANCL Corporation, 12-13, Kamishinano, Totsuka-ku, Yokohama, Kanagawa, 244-0806, Japan
| | - Kei Yui
- FANCL Health Science Research Center, Research Institute, FANCL Corporation, 12-13, Kamishinano, Totsuka-ku, Yokohama, Kanagawa, 244-0806, Japan
| | - Yoshihito Shimazu
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan
| | - Mamoru Takeda
- Laboratory of Food and Physiological Sciences, Department of Life and Food Sciences, School of Life and Environmental Sciences, Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan.
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