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Mo SY, Xue Y, Li Y, Zhang YJ, Xu XX, Fu KY, Sessle BJ, Xie QF, Cao Y. Descending serotonergic modulation from rostral ventromedial medulla to spinal trigeminal nucleus is involved in experimental occlusal interference-induced chronic orofacial hyperalgesia. J Headache Pain 2023; 24:50. [PMID: 37165344 PMCID: PMC10173589 DOI: 10.1186/s10194-023-01584-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 04/21/2023] [Indexed: 05/12/2023] Open
Abstract
BACKGROUND Dental treatment associated with unadaptable occlusal alteration can cause chronic primary myofascial orofacial pain. The serotonin (5-HT) pathway from the rostral ventromedial medulla (RVM) exerts descending modulation on nociceptive transmission in the spinal trigeminal nucleus (Sp5) and facilitates chronic pain. The aim of this study was to investigate whether descending 5-HT modulation from the RVM to the Sp5 is involved in the maintenance of primary myofascial orofacial hyperalgesia after persistent experimental occlusal interference (PEOI) or after delayed removal of experimental occlusal interference (REOI). METHODS Expressions of 5-HT3A and 5-HT3B receptor subtypes in the Sp5 were assessed by immunofluorescence staining and Western blotting. The release and metabolism of 5-HT in the Sp5 were measured by high-performance liquid chromatography. Changes in the pain behavior of these rats were examined after specific pharmacologic antagonism of the 5-HT3 receptor, chemogenetic manipulation of the RVM 5-HT neurons, or selective down-regulation of 5-HT synthesis in the RVM. RESULTS Upregulation of the 5-HT3B receptor subtype in the Sp5 was found in REOI and PEOI rats. The concentration of 5-HT in Sp5 increased significantly only in REOI rats. Intrathecal administration of Y-25130 (a selective 5-HT3 receptor antagonist) dose-dependently reversed the hyperalgesia in REOI rats but only transiently reversed the hyperalgesia in PEOI rats. Chemogenetic inhibition of the RVM 5-HT neurons reversed the hyperalgesia in REOI rats; selective down-regulation of 5-HT in advance also prevented the development of hyperalgesia in REOI rats; the above two manipulations did not affect the hyperalgesia in PEOI rats. However, chemogenetic activation of the RVM 5-HT neurons exacerbated the hyperalgesia both in REOI and PEOI rats. CONCLUSIONS These results provide several lines of evidence that the descending pathway from 5-HT neurons in the RVM to 5-HT3 receptors in the Sp5, plays an important role in facilitating the maintained orofacial hyperalgesia after delayed EOI removal, but has a limited role in that after persistent EOI.
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Affiliation(s)
- Si-Yi Mo
- Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, School and Hospital of Stomatology, Peking University, No.22, Zhongguancun South Avenue, Haidian District, Beijing, 100081, PR China
- National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, 100081, PR China
| | - Yang Xue
- Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, School and Hospital of Stomatology, Peking University, No.22, Zhongguancun South Avenue, Haidian District, Beijing, 100081, PR China
- National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, 100081, PR China
| | - Yuan Li
- Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, School and Hospital of Stomatology, Peking University, No.22, Zhongguancun South Avenue, Haidian District, Beijing, 100081, PR China
- National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, 100081, PR China
| | - Yao-Jun Zhang
- Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, School and Hospital of Stomatology, Peking University, No.22, Zhongguancun South Avenue, Haidian District, Beijing, 100081, PR China
- National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, 100081, PR China
| | - Xiao-Xiang Xu
- Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, School and Hospital of Stomatology, Peking University, No.22, Zhongguancun South Avenue, Haidian District, Beijing, 100081, PR China.
- National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, 100081, PR China.
| | - Kai-Yuan Fu
- National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, 100081, PR China
- Center for Temporomandibular Disorders and Orofacial Pain, School and Hospital of Stomatology, Peking University, Beijing, 100081, PR China
| | - Barry J Sessle
- Faculty of Dentistry & Department of Physiology, Temerty Faculty of Medicine & Centre for the Study of Pain, University of Toronto, Toronto, ON, M5G 1G6, Canada
| | - Qiu-Fei Xie
- Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, School and Hospital of Stomatology, Peking University, No.22, Zhongguancun South Avenue, Haidian District, Beijing, 100081, PR China
- National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, 100081, PR China
| | - Ye Cao
- Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, School and Hospital of Stomatology, Peking University, No.22, Zhongguancun South Avenue, Haidian District, Beijing, 100081, PR China.
- National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, 100081, PR China.
- Key Laboratory for Neuroscience, Ministry of Education/National Health Commission of the People's Republic of China, Peking University, Beijing, 100083, PR China.
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Leitão AWA, Borges MMF, Martins JODL, Coelho AA, Carlos ACAM, Alves APNN, Silva PGDB, Sousa FB. Celecoxib in the treatment of orofacial pain and discomfort in rats subjected to a dental occlusal interference model. Acta Cir Bras 2022; 37:e370506. [PMID: 35976283 PMCID: PMC9377653 DOI: 10.1590/acb370506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 04/11/2022] [Indexed: 11/24/2022] Open
Abstract
Purpose: To evaluate the effect of a selective cyclooxygenase 2 (COX-2) inhibitor on trigeminal ganglion changes and orofacial discomfort/nociception in rats submitted to an experimental model of dental occlusal interference (DOI). Methods: Female Wistar rats (180-200 g) were divided into five groups: a sham group (without DOI) (n=15); and four experimental groups with DOI treated daily with 0.1 mL/kg saline (DOI+SAL), 8, 16, or 32 mg/kg celecoxib (DOI+cel -8, -16, -32) (n=30/group). The animals were euthanized after one, three, and seven days. The bilateral trigeminal ganglia were analyzed histomorphometrically (neuron cell body area) and immunohistochemically (COX-2, nuclear factor-kappa B [NFkB], and peroxisome proliferator-activated receptor-y [PPARy]). A bilateral nociception assay of the masseter muscle was performed. The number of bites/scratches, weight, and grimace scale scores were determined daily. One-way/two-way analysis of variance (ANOVA)/Bonferroni post hoc tests were used (P < .05, GraphPad Prism 5.0). Results: DOI+SAL showed a reduction in neuron cell body area bilaterally, whereas DOI+cel-32 exhibited a significative increase in neuron cell body area compared with DOI+SAL group (P < 0.05). The ipsilateral (P=0.007 and P=0.039) and contralateral (P < 0.001 and P=0.005) overexpression of COX-2 and NFkB and downregulation of PPARy (P=0.016 and P < 0.001) occurred in DOI+SAL, but DOI+cel-32 reverted this alteration. DOI+SAL showed increase in isplateral (P < 0.001) and contralateral (P < 0.001) nociception, an increased number of bites (P=0.010), scratches (P < 0.001), and grimace scores (P=0.032). In the group of DOI+cel-32, these parameters were reduced. Conclusions: Celecoxib attenuated DOI-induced transitory nociception/orofacial discomfort resulting from trigeminal COX-2 overexpression.
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Affiliation(s)
- Andrea Whitehurst Ary Leitão
- Master. Centro Univeristário Christus - Department of Dentistry - Laboratory of Oral Pathology - Fortaleza (CE), Brazil
| | - Marcela Maria Fontes Borges
- Fellow Master degree. Universidade Federal do Ceará - Faculty of Pharmacy, Dentistry and Nursing - Division of Oral Pathology - Fortaleza (CE), Brazil
| | - Joyce Ohana de Lima Martins
- Fellow Master degree. Universidade Federal do Ceará - Faculty of Pharmacy, Dentistry and Nursing - Division of Oral Pathology - Fortaleza (CE), Brazil
| | - Antônio Alexandre Coelho
- Graduate student. Centro Univeristário Christus - Department of Dentistry - Fortaleza (CE), Brazil
| | | | - Ana Paula Negreiros Nunes Alves
- PhD, Full Professor. Universidade Federal do Ceará - Faculty of Pharmacy, Dentistry and Nursing - Division of Oral Pathology - Fortaleza (CE), Brazil
| | - Paulo Goberlânio de Barros Silva
- PhD, Full Professor. Centro Univeristário Christus - Department of Dentistry - Laboratory of Oral Pathology - Fortaleza (CE), Brazil
| | - Fabrício Bitu Sousa
- PhD, Full Professor. Centro Univeristário Christus - Department of Dentistry - Laboratory of Oral Pathology - Fortaleza (CE), Brazil
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Cao Y. Occlusal disharmony and chronic oro-facial pain: from clinical observation to animal study. J Oral Rehabil 2021; 49:116-124. [PMID: 34333797 DOI: 10.1111/joor.13236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 06/24/2021] [Accepted: 07/17/2021] [Indexed: 12/21/2022]
Abstract
BACKGROUND Occlusion can be viewed as the most sensitive susceptor of the central nervous system in the oro-facial region. Its inalienable relationships to the temporomandibular joint, the muscles, the stomatognathic system and even the central nervous system are self-evident. Almost all the dental treatments inevitably change the occlusion, potentially or actually, locally or extensively, and immediately or gradually. OBJECTIVE The objective of this study was to present a narrative literature on occlusal disharmony and chronic oro-facial pain. METHODS Literature reviews focusing on clinical studies about the relationship between occlusal disharmony and myofascial oro-facial pain, and related preclinical studies about the animal models of, as well as the peripheral and central mechanisms underlying this condition related to, occlusal disharmony were used as starting point and guidelines to describe the topics mentioned. A search of the PubMed database was performed mainly with the following search terms: "occlusion," "occlusal interference," "occlusal disharmony," "occlusal change," "oro-facial pain" and "myofascial pain." RESULTS Relevant literature from the past 70 years until the present day was meticulously studied. The literature review together with three related characteristic clinical cases revealed an intimate association between occlusal disharmony and chronic oro-facial pain, involving pathological changes, extending from the peripheral tissues to the central nervous system. The patients suffered from psychological distress, sleep disturbance and poor life quality. CONCLUSION Occlusal disharmony-related oro-facial pain is a clinical problem that deserves attention, although there are no universally accepted clinical protocols. The existing literature provides some constructive suggestions, but further research is needed.
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Affiliation(s)
- Ye Cao
- Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Peking University School and Hospital of Stomatology, Beijing, China.,Center for TMD & Orofacial Pain, Peking University School and Hospital of Stomatology, Beijing, China.,National Clinical Research Center for Oral Diseases, National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing Key Laboratory of Digital Stomatology, Beijing, China
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Mo SY, Bai SS, Xu XX, Liu Y, Fu KY, Sessle BJ, Cao Y, Xie QF. Astrocytes in the rostral ventromedial medulla contribute to the maintenance of oro-facial hyperalgesia induced by late removal of dental occlusal interference. J Oral Rehabil 2021; 49:207-218. [PMID: 34042200 DOI: 10.1111/joor.13211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/29/2021] [Accepted: 05/18/2021] [Indexed: 11/27/2022]
Abstract
BACKGROUND Astrocytes in the rostral ventromedial medulla (RVM) contribute to descending pain modulation, but their role in oro-facial pain induced by persistent experimental dental occlusal interference (PEOI) or following EOI removal (REOI) is unknown. OBJECTIVE To explore the involvement of RVM astrocytes in PEOI-induced oro-facial hyperalgesia or its maintenance following REOI. METHODS Male rats were randomly assigned into five groups: sham-EOI, postoperative day 6 and 14 of PEOI (PEOI 6 d and PEOI 14 d), postoperative day 6 following REOI on day 3 (REOI 3 d) and postoperative day 14 following REOI on day 8 (REOI 8 d). The nociceptive head withdrawal threshold (HWT) and activities of RVM ON- or OFF-cells were recorded before and after intra-RVM astrocyte gap junction blocker carbenoxolone (CBX) microinjection. RVM astrocytes were labelled immunohistochemically with glial fibrillary acidic protein (GFAP) and analysed semi-quantitatively. RESULTS Persistent experimental dental occlusal interference-induced oro-facial hyperalgesia, as reflected in decreased HWTs, was partially inhibited by REOI at day 3 but not at day 8 after EOI placement. Increased GFAP-staining area occurred only in REOI 8 d group in which CBX could inhibit the maintained hyperalgesia; CBX was ineffective in inhibiting hyperalgesia in PEOI 14 d group. OFF-cell activities showed no change, but the spontaneous activity and responses of ON-cells were significantly enhanced that could be suppressed by CBX in REOI 8 d group. CONCLUSION Rostral ventromedial medulla astrocytes may not participate in PEOI-induced oro-facial hyperalgesia or hyperalgesia inhibition by early REOI but are involved in the maintenance of oro-facial hyperalgesia by late REOI.
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Affiliation(s)
- Si-Yi Mo
- Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing, China
| | - Shan-Shan Bai
- Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing, China
| | - Xiao-Xiang Xu
- Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing, China
| | - Yun Liu
- Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing, China
| | - Kai-Yuan Fu
- Center for TMD & Orofacial Pain, Peking University School & Hospital of Stomatology, Beijing, China
| | - Barry J Sessle
- Faculty of Dentistry, and Department of Physiology, Faculty of Medicine, and Centre for the Study of Pain, University of Toronto, Toronto, ON, Canada
| | - Ye Cao
- Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing, China
| | - Qiu-Fei Xie
- Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing, China
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Chung MK, Wang S, Yang J, Alshanqiti I, Wei F, Ro JY. Neural Pathways of Craniofacial Muscle Pain: Implications for Novel Treatments. J Dent Res 2020; 99:1004-1012. [PMID: 32374638 DOI: 10.1177/0022034520919384] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Craniofacial muscle pain is highly prevalent in temporomandibular disorders but is difficult to treat. Enhanced understanding of neurobiology unique to craniofacial muscle pain should lead to the development of novel mechanism-based treatments. Herein, we review recent studies to summarize neural pathways of craniofacial muscle pain. Nociceptive afferents in craniofacial muscles are predominantly peptidergic afferents enriched with TRPV1. Signals from peripheral glutamate receptors converge onto TRPV1, leading to mechanical hyperalgesia. Further studies are needed to clarify whether hyperalgesic priming in nonpeptidergic afferents or repeated acid injections also affect craniofacial muscle pain. Within trigeminal ganglia, afferents innervating craniofacial muscles interact with surrounding satellite glia, which enhances the sensitivity of the inflamed neurons as well as nearby uninjured afferents, resulting in hyperalgesia and ectopic pain originating from adjacent orofacial tissues. Craniofacial muscle afferents project to a wide area within the trigeminal nucleus complex, and central sensitization of medullary dorsal horn neurons is a critical factor in muscle hyperalgesia related to ectopic pain and emotional stress. Second-order neurons project rostrally to pathways associated with affective pain, such as parabrachial nucleus and medial thalamic nucleus, as well as sensory-discriminative pain, such as ventral posteromedial thalamic nuclei. Abnormal endogenous pain modulation can also contribute to chronic muscle pain. Descending serotonergic circuits from the rostral ventromedial medulla facilitate activation of second-order neurons in the trigeminal nucleus complex, which leads to the maintenance of mechanical hyperalgesia of inflamed masseter muscle. Patients with temporomandibular disorders exhibit altered brain networks in widespread cortical and subcortical regions. Recent development of methods for neural circuit manipulation allows silencing of specific hyperactive neural circuits. Chemogenetic silencing of TRPV1-expressing afferents or rostral ventromedial medulla neurons attenuates hyperalgesia during masseter inflammation. It is likely, therefore, that further delineation of neural circuits mediating craniofacial muscle hyperalgesia potentially enhances treatment of chronic muscle pain conditions.
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Affiliation(s)
- M K Chung
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, MD, USA
| | - S Wang
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, MD, USA
| | - J Yang
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, MD, USA
| | - I Alshanqiti
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, MD, USA
| | - F Wei
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, MD, USA
| | - J Y Ro
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, MD, USA
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Silva PGDB, de Lima Martins JO, de Lima Praxedes Neto RA, Mota Lemos JV, Machado LC, Matos Carlos ACA, Alves APNN, Lima RA. Tumor necrosis factor alpha mediates orofacial discomfort in an occlusal dental interference model in rats: The role of trigeminal ganglion inflammation. J Oral Pathol Med 2019; 49:169-176. [PMID: 31829463 DOI: 10.1111/jop.12984] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 11/28/2019] [Accepted: 12/05/2019] [Indexed: 01/09/2023]
Abstract
BACKGROUND Tumor necrosis factor alpha (TNF-α) is a proinflammatory cytokine that plays an important role in the early stages of inflammation. In this study, we investigated its role in orofacial discomfort in rats subjected to occlusal dental interference (ODI). METHODS Female Wistar rats (180-200 g) were divided in three groups (n = 30/group): sham group, without ODI, and two experimental groups with ODI pre-treated with 0.1 mL/kg saline (ODI + SAL) or 5 mg/kg infliximab (ODI + INF) and treated every 3 days. The animals were euthanized after 1, 3, and 7 days. The number of bites and scratches and grimace scale scores were determined daily, and the bilateral trigeminal ganglion was histomorphometrically (neuronal body area) analyzed and submitted for immunohistochemistry for TNF-α, nitric oxide synthesis (NOS) neuronal (nNOS) and inducible (iNOS), peroxisome proliferator-activated receptors (PPAR) y (PPARy) and δ/β (PPARδ/β), and glial fibrillary acidic protein (GFAP). One-way/two-way ANOVA/Bonferroni tests were used (P < .05, GraphPad Prism 5.0). RESULTS ODI + SAL showed a large number of bites (P = .002), scratches (P = .002), and grimace scores (P < .001) in the firsts days, and ODI + INF partially reduced these parameters. The contralateral and ipsilateral neuronal body area was significantly reduced on day 1 in ODI + SAL, but returned to the basal size on days 3 and 7, by increase in TNF-α, nNOS, PPARy, PPARδ/β, and GFAP immunostaining. The infliximab treatment attenuated these alterations (P < .05). There was no iNOS immunostaining. CONCLUSION Occlusal dental interference induced transitory orofacial discomfort by trigeminal inflammatory mediator overexpression, and TNF-α blockage attenuated these processes.
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Affiliation(s)
| | | | | | | | | | | | - Ana Paula Negreiros Nunes Alves
- Division of Oral Pathology, Department of Dental Clinic, Faculty of Pharmacy, Dentistry and Nursing, Federal University of Ceara, Fortaleza, Brazil
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Occlusal interference induces oxidative stress and increases the expression of UCP3 in the masseter muscle: A rat model. Arch Oral Biol 2019; 102:249-255. [PMID: 31096116 DOI: 10.1016/j.archoralbio.2019.04.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 04/17/2019] [Accepted: 04/30/2019] [Indexed: 12/16/2022]
Abstract
OBJECTIVE To determine whether occlusal alteration contributes to masticatory muscle damage by inducing oxidative stress. DESIGN Thirty Sprague-Dawley rats were randomly divided into six groups, including occlusal interference groups (3 days, 7 days, 14 days, 21 days, and removal for 3 days) and a sham group. A rat experimental model of occlusal interference was generated by a 0.6-mm unilateral bite-raise. The rats were euthanised for evaluation of histologic changes in the masseter muscles using haematoxylin-eosin staining. To further investigate the role of oxidative stress and uncoupling protein (UCP3) in the development of occlusal dysfunction-induced masseter damage, levels of UCP3 protein were measured by western blot analysis. RESULTS Compared with the sham group, the connective tissue of the masseter muscle was extended partially and inflammatory cells appeared following the induction of malocclusion. With respect to the oxidative stress markers, there were increases in malondialdehyde (MDA) content but decreases in superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities; furthermore, the expression of UCP3 was upregulated. After eliminating the occlusal interference for 3 days, the degree of inflammation was substantially alleviated, the MDA content decreased, and SOD and GPX activities increased. The expression of UCP3 decreased. CONCLUSIONS Occlusal interference induces oxidative stress in the masseter muscle, regulated by UCP3. Overall, these findings have significant implications for the understanding of how occlusal dysfunction causes muscle fatigue and pain.
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