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Zou Z, Fan W, Liu H, Liu Q, He H, Huang F. The roles of 5-HT in orofacial pain. Oral Dis 2024. [PMID: 38622872 DOI: 10.1111/odi.14960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/10/2024] [Accepted: 04/02/2024] [Indexed: 04/17/2024]
Abstract
OBJECTIVES Acute and chronic orofacial pain are very common and remain a vexing health problem that has a negative effect on the quality of life. Serotonin (5-HydroxyTryptamine, 5-HT) is a kind of monoamine neurotransmitter that is involved in many physiological and pathological processes. However, its role in orofacial pain remains inconclusive. Therefore, this review aims to summarize the recent advances in understanding the effect exerted by 5-HT on the modulation of orofacial pain. SUBJECTS AND METHODS An extensive search was conducted on PubMed and Web of Science for pertinent studies focusing on the effects of 5-HT on the modulation of orofacial pain. RESULTS In this review, we concisely review how 5-HT mediates orofacial pain, how 5-HT is regulated and how we can translate these findings into clinical applications for the prevention and/or treatment of orofacial pain. CONCLUSIONS 5-HT plays a key role in the modulation of orofacial pain, implying that 5-HT modulators may serve as effective treatment for orofacial pain. However, further research on the precise mechanisms underlying the modulation of orofacial pain is still warranted.
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Affiliation(s)
- Zhishan Zou
- Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Wenguo Fan
- Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Haotian Liu
- Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Qing Liu
- Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, Hong Kong, SAR, China
| | - Hongwen He
- Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Fang Huang
- Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
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Okamoto K, Hasegawa M, Piriyaprasath K, Kakihara Y, Saeki M, Yamamura K. Preclinical models of deep craniofacial nociception and temporomandibular disorder pain. JAPANESE DENTAL SCIENCE REVIEW 2021; 57:231-241. [PMID: 34815817 PMCID: PMC8593658 DOI: 10.1016/j.jdsr.2021.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 10/15/2021] [Accepted: 10/19/2021] [Indexed: 01/06/2023] Open
Abstract
Chronic pain in temporomandibular disorder (TMD) is a common health problem. Cumulating evidence indicates that the etiology of TMD pain is complex with multifactorial experience that could hamper the developments of treatments. Preclinical research is a resource to understand the mechanism for TMD pain, whereas limitations are present as a disease-specific model. It is difficult to incorporate multiple risk factors associated with the etiology that could increase pain responses into a single animal. This article introduces several rodent models which are often employed in the preclinical studies and discusses their validities for TMD pain after the elucidations of the neural mechanisms based on the clinical reports. First, rodent models were classified into two groups with or without inflammation in the deep craniofacial tissues. Next, the characteristics of each model and the procedures to identify deep craniofacial pain were discussed. Emphasis was directed on the findings of the effects of chronic psychological stress, a major risk factor for chronic pain, on the deep craniofacial nociception. Preclinical models have provided clinically relevant information, which could contribute to better understand the basis for TMD pain, while efforts are still required to bridge the gap between animal and human studies.
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Affiliation(s)
- Keiichiro Okamoto
- Division of Oral Physiology, Niigata University Graduate School of Medical and Dental Sciences, 2-5274, Gakkocho-dori, Chuo-ku, Niigata City, 951-8514, Japan
| | - Mana Hasegawa
- Division of Oral Physiology, Niigata University Graduate School of Medical and Dental Sciences, 2-5274, Gakkocho-dori, Chuo-ku, Niigata City, 951-8514, Japan.,Division of Dental Clinical Education, Niigata University Graduate School of Medical and Dental Sciences, 2-5274, Gakkocho-dori, Chuo-ku, Niigata City, 951-8514, Japan
| | - Kajita Piriyaprasath
- Division of Oral Physiology, Niigata University Graduate School of Medical and Dental Sciences, 2-5274, Gakkocho-dori, Chuo-ku, Niigata City, 951-8514, Japan
| | - Yoshito Kakihara
- Division of Dental Pharmacology, Niigata University Graduate School of Medical and Dental Sciences, 2-5274, Gakkocho-dori, Chuo-ku, Niigata City, 951-8514, Japan
| | - Makio Saeki
- Division of Dental Pharmacology, Niigata University Graduate School of Medical and Dental Sciences, 2-5274, Gakkocho-dori, Chuo-ku, Niigata City, 951-8514, Japan
| | - Kensuke Yamamura
- Division of Oral Physiology, Niigata University Graduate School of Medical and Dental Sciences, 2-5274, Gakkocho-dori, Chuo-ku, Niigata City, 951-8514, Japan
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Pecikoza U, Tomić M, Micov A, Vuković M, Stepanović-Petrović R. Eslicarbazepine acetate interacts in a beneficial manner with standard and alternative analgesics to reduce trigeminal nociception. Psychopharmacology (Berl) 2020; 237:1435-1446. [PMID: 32025776 DOI: 10.1007/s00213-020-05470-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 01/21/2020] [Indexed: 11/29/2022]
Abstract
RATIONALE Acute pain states in the trigeminal region (headaches, dental pain) fall into the most prevalent painful conditions. Standard analgesics (paracetamol/NSAIDs) represent the cornerstone of their treatment, whereas triptans are primarily used in migraine attacks. Due to limited efficacy and/or side effects of current treatments, identifying favorable combinations of available drugs is justified. OBJECTIVES Eslicarbazepine acetate (ESL) is a novel antiepileptic drug whose effectiveness against trigeminal pain was recently demonstrated. Here, we examined the interactions between ESL and several standard/alternative analgesics (paracetamol, propyphenazone, naproxen, zolmitriptan, and metoclopramide) in a model of trigeminal pain. METHODS The antinociceptive effects of orally administered ESL, standard/alternative analgesics, and two-drug ESL-analgesic combinations were examined in the orofacial formalin test in mice. The type of interaction between drugs was determined by isobolographic analysis. RESULTS ESL, analgesics, and two-drug ESL-analgesic combinations significantly and dose-dependently reduced nociceptive behaviour in the second, inflammatory phase of the test. Isobolographic analysis revealed that ESL interacted additively with paracetamol/propyphenazone/zolmitriptan and synergistically with naproxen/metoclopramide (with about a 4-fold and 3-fold reduction of doses in the ESL-naproxen and ESL-metoclopramide combination, respectively). CONCLUSIONS ESL interacted in a beneficial manner with several analgesics that are used for trigeminal pain treatment, producing synergistic interactions with naproxen/metoclopramide and additive interactions with paracetamol/propyphenazone/zolmitriptan. Our results suggest that combining ESL with analgesics could theoretically enable the use of lower doses of individual drugs for achieving pain relief.
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Affiliation(s)
- Uroš Pecikoza
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, P.O. Box 146, Belgrade, 11221, Serbia.
| | - Maja Tomić
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, P.O. Box 146, Belgrade, 11221, Serbia
| | - Ana Micov
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, P.O. Box 146, Belgrade, 11221, Serbia
| | - Milja Vuković
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, P.O. Box 146, Belgrade, 11221, Serbia
| | - Radica Stepanović-Petrović
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, P.O. Box 146, Belgrade, 11221, Serbia
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Moreno-Fernández AM, Jiménez-Castellanos E, Iglesias-Linares A, Bueso-Madrid D, Fernández-Rodríguez A, de Miguel M. Fibromyalgia syndrome and temporomandibular disorders with muscular pain. A review. Mod Rheumatol 2017; 27:210-216. [DOI: 10.1080/14397595.2016.1221788] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Ana Maria Moreno-Fernández
- Departamento de Citología e Histología Normal y Patológica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain,
| | | | - Alejandro Iglesias-Linares
- Departamento de Estomatología IV, Facultad de Odontología, Universidad Complutense de Madrid, Madrid, Spain
| | - Débora Bueso-Madrid
- Departamento de Estomatología, Facultad de Odontología, Universidad de Sevilla, Sevilla, Spain, and
| | - Ana Fernández-Rodríguez
- Departamento de Citología e Histología Normal y Patológica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain,
| | - Manuel de Miguel
- Departamento de Citología e Histología Normal y Patológica, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain,
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Imbe H, Kimura A. Repeated forced swim stress affects the expression of pCREB and ΔFosB and the acetylation of histone H3 in the rostral ventromedial medulla and locus coeruleus. Brain Res Bull 2016; 127:11-22. [PMID: 27530066 DOI: 10.1016/j.brainresbull.2016.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Revised: 08/10/2016] [Accepted: 08/11/2016] [Indexed: 01/31/2023]
Abstract
The rostral ventromedial medulla (RVM) and locus coeruleus (LC) play crucial roles in descending pain modulation system. In the present study we examined the expression of phospho-cAMP response element-binding protein (pCREB) and ΔFosB and the acetylation of histone H3 in the RVM and LC after forced swim stress (FS) and complete Freund's adjuvant (CFA) injection to clarify changes in descending pain modulatory system in a rat model of stress-induced hyperalgesia. FS (day 1, 10min; days 2-3, 20min) induced a significant increase in the expression of pCREB and ΔFosB and the acetylation of histone H3 in the RVM, whereas the FS induced a significant increase only in the acetylation of histone H3 in the LC. CFA injection into the hindpaw did not induce a significant change in those expression and acetylation. Quantitative image analysis demonstrated that the numbers of pCREB-, acetylated histone H3- and ΔFosB-IR cells in the RVM were significantly higher in the FS group than those in the naive group. The CFA injection after the FS did not affect the FS-induced increases in the expression of pCREB and ΔFosB and the acetylation of histone H3 in the RVM even though nullified the increase in the acetylation of histone H3 in the LC. These findings suggest different neuroplasticities between the RVM and LC after the FS, which may be involved in activity change of descending pain modulatory system after the CFA injection.
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Affiliation(s)
- Hiroki Imbe
- Department of Physiology, Wakayama Medical University, Kimiidera 811-1, Wakayama City, 641-8509, Japan.
| | - Akihisa Kimura
- Department of Physiology, Wakayama Medical University, Kimiidera 811-1, Wakayama City, 641-8509, Japan
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Preparation, Characterization, and Pharmacological Activity of Cymbopogon winterianus Jowitt ex Bor (Poaceae) Leaf Essential Oil of β-Cyclodextrin Inclusion Complexes. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 2015:502454. [PMID: 26246838 PMCID: PMC4515525 DOI: 10.1155/2015/502454] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 06/11/2015] [Accepted: 06/16/2015] [Indexed: 01/09/2023]
Abstract
This study aimed to evaluate the orofacial antinociceptive effect of the Cymbopogon winterianus essential oil (LEO) complexed in β-cyclodextrin (LEO-CD) and to assess the possible involvement of the central nervous system (CNS). The LEO was extracted, chromatographed, and complexed in β-cyclodextrin. The complex was characterized by differential scanning calorimetry (DSC) and thermogravimetry derivative (TG/DTG). Male Swiss mice (2-3 months) were treated with LEO-CD (50-200 mg/kg, p.o.), vehicle (distilled water, p.o.), or standard drug (i.p.) and subjected to the orofacial nociception formalin-, capsaicin-, and glutamate-induced. After the formalin test, the animals were perfused and the brains subjected to immunofluorescence for Fos. The rota-rod test (7 rpm/min) was carried out. Geraniol (37.57%) was the main compound of LEO. DSC and TG/DTG proved the complexation. The orofacial nociceptive behavior was significantly (p < 0.05) reduced. The number of Fos-positive cells was significantly changed in the dorsal raphe nucleus (p < 0.01), locus coeruleus (p < 0.001), trigeminal nucleus (p < 0.05), and trigeminal thalamic tract (p < 0.05). LEO-CD did not cause changes in motor coordination in the rota-rod test. Thus, our results suggested that LEO-CD has an orofacial antinociceptive profile, probably mediated by the activation of the CNS without changing the motor coordination.
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Okamoto K, Katagiri A, Rahman M, Thompson R, Bereiter DA. Inhibition of temporomandibular joint input to medullary dorsal horn neurons by 5HT3 receptor antagonist in female rats. Neuroscience 2015; 299:35-44. [PMID: 25913635 DOI: 10.1016/j.neuroscience.2015.04.037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 03/17/2015] [Accepted: 04/16/2015] [Indexed: 12/19/2022]
Abstract
Repeated forced swim (FS) conditioning enhances nociceptive responses to temporomandibular joint (TMJ) stimulation in female rats. The basis for FS-induced TMJ hyperalgesia remains unclear. To test the hypothesis that serotonin 3 receptor (5HT3R) mechanisms contribute to enhanced TMJ nociception after FS, ovariectomized female rats were treated with estradiol and subjected to FS for three days. On day 4, rats were anesthetized with isoflurane and TMJ-responsive neurons were recorded from superficial and deep laminae at the trigeminal subnucleus caudalis/upper cervical (Vc/C1-2) region and electromyographic (EMG) activity was recorded from the masseter muscle. Only Vc/C1-2 neurons activated by intra-TMJ injections of ATP were included for further analysis. Although neurons in both superficial and deep laminae were activated by ATP, only neurons in deep laminae displayed enhanced responses after FS. Local application of the 5HT3R antagonist, ondansetron (OND), at the Vc/C1-2 region reduced the ATP-evoked responses of neurons in superficial and deep laminae and reduced the EMG response in both sham and FS rats. OND also decreased the spontaneous firing rate of neurons in deep laminae and reduced the high-threshold convergent cutaneous receptive field area of neurons in superficial and deep laminae in both sham and FS rats. These results revealed that central application of a 5HT3R antagonist, had widespread effects on the properties of TMJ-responsive neurons at the Vc/C1-2 region and on jaw muscle reflexes under sham and FS conditions. It is concluded that 5HT3R does not play a unique role in mediating stress-induced hyperalgesia related to TMJ nociception.
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Affiliation(s)
- K Okamoto
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, United States.
| | - A Katagiri
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, United States
| | - M Rahman
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, United States
| | - R Thompson
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, United States
| | - D A Bereiter
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, United States
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Functional expression of 5-HT7 receptor on the substantia gelatinosa neurons of the trigeminal subnucleus caudalis in mice. Brain Res 2014. [DOI: 10.1016/j.brainres.2013.10.041] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Role of peripheral and spinal 5-HT3 receptors in development and maintenance of formalin-induced long-term secondary allodynia and hyperalgesia. Pharmacol Biochem Behav 2012; 101:246-57. [DOI: 10.1016/j.pbb.2012.01.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 01/13/2012] [Accepted: 01/16/2012] [Indexed: 12/19/2022]
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Sokolov AY, Lyubashina OA, Panteleev SS. The role of serotonin receptors in migraine headaches. NEUROCHEM J+ 2011. [DOI: 10.1134/s1819712411020085] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Yin H, Park SA, Han SK, Park SJ. Effects of 5-hydroxytryptamine on substantia gelatinosa neurons of the trigeminal subnucleus caudalis in immature mice. Brain Res 2010; 1368:91-101. [PMID: 20971089 DOI: 10.1016/j.brainres.2010.10.050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 10/11/2010] [Accepted: 10/14/2010] [Indexed: 12/21/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) is involved in the descending modulation of nociceptive transmission in the spinal dorsal horn. The trigeminal subnucleus caudalis (Vc; medullary dorsal horn) processes nociceptive input from the orofacial region, and 5-HT-containing axons are numerous in the superficial layers of the Vc. This study examined the actions of 5-HT on the substantia gelatinosa (SG) neurons of the Vc, using gramicidin-perforated patch-clamp recording in brainstem slice preparations from immature mice. In order to clarify the possible mechanisms underlying 5-HT actions in the SG of the Vc, the direct membrane effects of 5-HT and effects of 5-HT receptor subtype agonists were examined. 5-HT induced a hyperpolarization in the majority (64/115, 56%) of the SG neurons tested. Thirty nine (34%) SG neurons showed no response, and 12 (10%) neurons responded with depolarization. The hyperpolarizing response to 5-HT was concentration-dependent (0.1-30 μM; n=7), not desensitized by repeated application (n=22), and significantly attenuated by Ba(2+) (K(+) channel blocker; n=8). The 5-HT-induced hyperpolarization was maintained in the presence of TTX (Na(+) channel blocker), CNQX (non-NMDA glutamate receptor antagonist), AP5 (NMDA glutamate receptor antagonist), picrotoxin (GABA(A) receptor antagonist), and strychnine (glycine receptor antagonist), indicating direct postsynaptic action of 5-HT on SG neurons (n=7). The 5-HT-induced hyperpolarizing effects were mimicked by 8-OH-DPAT (5-HT(1A) receptor agonist) and α-methyl-5-HT (5-HT(2) receptor agonist) and blocked by WAY-100635 (5-HT(1A) receptor antagonist) and ketanserin (5-HT(2) receptor antagonist). Single-cell RT-PCR also revealed the presence of mRNA for 5-HT(1A) and 5-HT(2C) subtypes in the SG neurons. These results suggest that 5-HT acts directly on SG neurons and 5-HT-induced hyperpolarization is mediated, in part, by 5-HT(1A) receptors and 5-HT(2) receptors, as well as by the activation of K(+) channels, indicating an important role for 5-HT in the modulation of orofacial nociceptive processing at the level of the SG of the Vc in mice.
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Affiliation(s)
- Hua Yin
- Department of Oral Physiology and Institute of Oral Bioscience, School of Dentistry, Chonbuk National University, Jeonju, Jeonbuk, 561-756, Republic of Korea
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Tashiro A, Okamoto K, Bereiter DA. Chronic inflammation and estradiol interact through MAPK activation to affect TMJ nociceptive processing by trigeminal caudalis neurons. Neuroscience 2009; 164:1813-20. [PMID: 19786077 DOI: 10.1016/j.neuroscience.2009.09.058] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 09/21/2009] [Accepted: 09/22/2009] [Indexed: 12/21/2022]
Abstract
The mitogen-activated protein kinase/extracellular regulated kinase (MAPK/ERK) pathway plays a key role in mediating estrogen actions in the brain and neuronal sensitization during inflammation. Estrogen status is a risk factor in chronic temporomandibular muscle/joint (TMJ) disorders; however, the basis for this relationship is not known. The present study tested the hypothesis that estrogen status acts through the MAPK/ERK signaling pathway to alter TMJ nociceptive processing. Single TMJ-responsive neurons were recorded in laminae I-II at the spinomedullary (Vc/C(1-2)) junction in naïve ovariectomized (OvX) female rats treated for 2 days with high-dose (20 microg/day; HE2) or low-dose estradiol (2 microg/day; LE2) and after chronic inflammation of the TMJ region by complete Freund's adjuvant for 12-14 days. Intra-TMJ injection of ATP (1 mM) was used to activate Vc/C(1-2) neurons. The MAPK/ERK inhibitor (PD98059, 0.01-1 mM) was applied topically to the dorsal Vc/C(1-2) surface at the site of recording 10 min prior to each ATP stimulus. In naïve HE2 rats, low-dose PD98059 caused a maximal inhibition of ATP-evoked activity, whereas even high doses had only minor effects on units in LE2 rats. By contrast, after chronic TMJ inflammation, PD98059 produced a marked and similar dose-related inhibition of ATP-evoked activity in HE2 and LE2 rats. These results suggested that E2 status and chronic inflammation acted, at least in part, through a common MAPK/ERK-dependent signaling pathway to enhance TMJ nociceptive processing by laminae I-II neurons at the spinomedullary junction region.
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Affiliation(s)
- A Tashiro
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, 18214 Moos Tower, Minneapolis, 515 Delaware Street SE, Minneapolis, MN 55455, USA.
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Okamoto K, Imbe H, Kimura A, Donishi T, Tamai Y, Senba E. Activation of central 5HT2A receptors reduces the craniofacial nociception of rats. Neuroscience 2007; 147:1090-102. [PMID: 17582689 DOI: 10.1016/j.neuroscience.2007.05.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 05/07/2007] [Accepted: 05/10/2007] [Indexed: 10/23/2022]
Abstract
We assessed the contribution of central 5HT2A receptors to the craniofacial tissue nociception in naïve male rats. First, we tested whether activation of central 5HT2A receptors affected nociceptive neural activities recorded from superficial laminae of the trigeminal subnucleus caudalis (Vc)/upper cervical spinal cord junction (Vc/C2) region. Two types of units, such as deep-nociceptive or skin-wide dynamic range (WDR) units were identified from extracellular recordings. Topical administration of 5HT2A receptor agonist, (+/-)-2,5-dimethoxy-4-iodoamphetamine (DOI) onto the Vc/C2 region significantly reduced deep-nociceptive unit discharges evoked by formalin injection into the masseter muscle. Noxious pinch stimulation to the facial skin-evoked skin-WDR unit discharges was significantly reduced by topical administration of 0.1 mg/rat DOI onto the Vc/C2 region. Second, we tested whether i.c.v. administration of DOI affected Fos-like immunoreactivity (-LI) evoked by formalin injection into the masseter muscle. Fos-LI was significantly induced mainly at the ventrolateral (vl) area of trigeminal subnucleus interpolaris (Vi)/Vc junction (vl-Vi/Vc) region and Vc/C2 region in vehicle-treated rats. Formalin-evoked Fos-LI was significantly reduced in laminae I-II of the Vc/C2, but not vl-Vi/Vc region after i.c.v. administration of DOI. Finally, orofacial nocifensive behavioral activities evoked by formalin injection into the masseter muscle were significantly reduced by intracisternal administration of DOI. These results suggest that 5HT2A receptors in the Vc/C2 region mediate antinociceptive effects in the craniofacial nociception.
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Affiliation(s)
- K Okamoto
- Department of Physiology, Wakayama Medical University, Kimiidera 811-1, Wakayama City, 641-8509, Japan.
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Okamoto K, Kimura A, Donishi T, Imbe H, Nishie Y, Matsushita H, Tamai Y, Senba E. Contribution of peripheral 5-HT2A or 5-HT3 receptors to Fos expression in the trigeminal spinal nucleus produced by acute injury to the masseter muscle during persistent temporomandibular joint inflammation in rats. Neuroscience 2006; 143:597-606. [PMID: 16979827 DOI: 10.1016/j.neuroscience.2006.08.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 07/17/2006] [Accepted: 08/07/2006] [Indexed: 12/30/2022]
Abstract
We investigated the contribution of peripheral 5-HT2A or 5-HT3 receptors to Fos expression in the trigeminal spinal nucleus (VSP) following acute masseter muscle injury in male rats with or without temporomandibular joint (TMJ) inflammation persisting for 7 days. TMJ inflammation was evoked by an injection of complete Freund's adjuvant (CFA). Two hours after formalin injection into the masseter muscle produced Fos-like immunoreactivity (Fos-LI) in several regions of the VSP and upper cervical spinal cord (C2), such as ventrolateral (vl) area of the trigeminal subnucleus caudalis (Vc)/subnucleus interpolaris (Vi) transition (vl-Vi/Vc), paratrigeminal nucleus (dPa5), middle portion of the Vc (mid-Vc) and Vc/C2 transition (Vc/C2) regions in both groups. Significant increases in the number of Fos-LI were observed in these areas in CFA group compared with non-CFA group. TMJ inflammation alone did not induce a significant level of Fos-LI in the VSP. In order to assess the effect of antagonizing 5-HT2A or 5-HT3 receptors on formalin-induced Fos-LI, rats were pre-treated with local (masseter muscle) administration of ketanserin or tropisetron (0.01, 0.1 mg/rat) 20 min prior to formalin injection. In CFA group, these antagonists given locally reduced the Fos-LI response in the laminae I-II at the mid-Vc and Vc/C2 regions. These antagonists reduced the Fos-LI response in the dPa5, but not in the vl-Vi/Vc region. The Fos-LI response was not affected by i.v. administration of ketanserin (0.01, 0.1 mg/rat) or tropisetron (0.01 mg/rat). In non-CFA group, these antagonists given locally did not reduce the Fos-LI response. These results suggest that peripheral 5-HT2A and 5-HT3 receptors contribute to nociceptive processing in the masseter muscle in TMJ inflammatory conditions.
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Affiliation(s)
- K Okamoto
- Department of Physiology, Wakayama Medical University, Wakayama City 641-8509, Japan.
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Oh SH, Imbe H, Iwai-Liao Y. TMJ inflammation increases Fos expression in the nucleus raphe magnus induced by subsequent formalin injection of the masseter or hindpaw of rats. Okajimas Folia Anat Jpn 2006; 83:43-52. [PMID: 16944837 DOI: 10.2535/ofaj.83.43] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The study was designed to examine the effect of persistent temporomandibular joint (TMJ) inflammation on neuronal activation in the descending pain modulatory system in response to noxious stimulus. Formalin was injected into the left masseter muscle or hindpaw of rats 10 days after injection of the left TMJ with saline or complete Freund's adjuvant (CFA). The results showed that 10-day persistent TMJ inflammation (induced by CFA) alone did not induce a significant increase in Fos-like immunoreactive (Fos-LI) neurons in the rostral ventromedial medulla (RVM) or locus coeruleus (LC), but that formalin injection of the masseter muscle or hindpaw induced a significant increase in Fos-LI neurons in the RVM and LC of rats with and without TMJ inflammation (P < 0.05). However, persistent TMJ inflammation significantly increased Fos-LI neurons in the nucleus raphe magnus (NRM) induced by subsequent formalin injection of the masseter muscle and hindpaw (70.2% increase and 53.8% increase, respectively, over the control TMJ-saline-injected rats; P < 0.05). The results suggest that persistent TMJ inflammation increases neuronal activity, in particularly in the NRM, by the plastic change of the descending pain modulatory system after ipsilateral application of a noxious stimulus to either orofacial area or a spatially remote body area.
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Affiliation(s)
- Sang-Hoon Oh
- Department of Oral Anatomy, Osaka Dental University, Kuzuhahanazono-cho 8-1, Hirakata-shi, 573-1121, Japan
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