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Pavlou IA, Spandidos DA, Zoumpourlis V, Papakosta VK. Neurobiology of bruxism: The impact of stress (Review). Biomed Rep 2024; 20:59. [PMID: 38414628 PMCID: PMC10895390 DOI: 10.3892/br.2024.1747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 01/30/2024] [Indexed: 02/29/2024] Open
Abstract
Bruxism is a non-functional involuntary muscle activity that affects more than one-third of the population at some point in their lives. A number of factors have been found to be related to the etiopathogenesis of bruxism; therefore, the condition is considered multifactorial. The most commonly accepted factor is stress. Stress has long been considered to increase muscle tone and to reduce the pain threshold. Current evidence indicates that exposure to chronic stress, distress and allostatic load ignite neurological degeneration and the attenuation of critical neuronal pathways that are highly implicated in the orofacial involuntary muscle activity. The present review discusses the negative effects that chronic stress exerts on certain parts of the central nervous system and the mechanisms through which these changes are involved in the etiopathogenesis of bruxism. The extent of these morphological and functional changes on nerves and neuronal tracts provides valuable insight into the obstacles that need to be overcome in order to achieve successful treatment. Additionally, particular emphasis is given on the effects of bruxism on the central nervous system, particularly the activation of the hypothalamic-pituitary-adrenal axis, as this subsequently induces an increase in circulating corticosterone levels, also evidenced by increased levels of salivary cortisol, thereby transforming bruxism into a self-reinforcing loop.
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Affiliation(s)
| | - Demetrios A Spandidos
- Laboratory of Clinical Virology, Medical School, University of Crete, 71003 Heraklion, Greece
| | - Vassilis Zoumpourlis
- Biomedical Applications Unit, Institute of Chemical Biology, National Hellenic Research Foundation, 11635 Athens, Greece
| | - Veronica K Papakosta
- Department of Oral and Maxillofacial Surgery, University Hospital Attikon, 12462 Athens, Greece
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Esmaeili A, Ebrahimpour S, Hefshejani KF, Esmaeili A. Molecular mechanisms underlying the effect of tooth shortening on memory dysfunction in Wistar male rat. Arch Oral Biol 2024; 159:105878. [PMID: 38171058 DOI: 10.1016/j.archoralbio.2023.105878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 12/15/2023] [Accepted: 12/27/2023] [Indexed: 01/05/2024]
Abstract
OBJECTIVE We investigated the effects of molar tooth shortening on the mRNA expression of the AβPP/BACE1, BDNF/TrkB, and Bax/Bcl-2 signaling pathways in the Wistar male rat hippocampal regions. DESIGN Four groups (n = 5 per group) of male Wistar rats (control, SRM (shortened right molar), SLM (shortened left molar), and SBM (shortened bilateral molar)) were used. RNA was isolated from the hippocampus and transformed into cDNA. Real-time quantitative PCR was used to evaluate the mRNA expression levels of AβPP, BACE1, Bax, Bcl-2, BDNF, and TrkB. RESULTS Differential mRNA expression was observed in rat groups. SBM significantly upregulated the AβPP, BACE1, and Bax mRNA expressions, whereas the expression levels of Bcl-2, BDNF, and TrkB were decreased. SRM and SLM approximately had the same effect on the expression enhancement of AβPP, BACE1, and Bax; however, SRM was more effective than SLM in increasing the expression of these genes. CONCLUSIONS Symmetrical molar teeth shortening affected the mRNA expression of AβPP and BACE1, which is related to learning and memory dysfunction.
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Affiliation(s)
- Ali Esmaeili
- Dental Materials Research Center, Dental Research Institute, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Shiva Ebrahimpour
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran
| | | | - Abolghasem Esmaeili
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran.
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Pavlou IA, Spandidos DA, Zoumpourlis V, Adamaki M. Nutrient insufficiencies and deficiencies involved in the pathogenesis of bruxism (Review). Exp Ther Med 2023; 26:563. [PMID: 37954114 PMCID: PMC10632959 DOI: 10.3892/etm.2023.12262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 10/02/2023] [Indexed: 11/14/2023] Open
Abstract
Stress has been well-documented to have a significant role in the etiopathogenesis of bruxism. Activation of the hypothalamic-pituitary-adrenal axis (HPA) and subsequent release of corticosteroids lead to increased muscle activity. Neurological studies have demonstrated that chronic stress exposure induces neurodegeneration of important neuronal structures and destabilization of the mesocortical dopaminergic pathway. These disruptions impair the abilities to counteract the overactivity of the HPA axis and disinhibit involuntary muscle activity, while at the same time, there is activation of the amygdala. Recent evidence shows that overactivation of the amygdala under stressful stimuli causes rhythmic jaw muscle activity by over activating the mesencephalic and motor trigeminal nuclei. The present review aimed to discuss the negative effects of certain vitamin and mineral deficiencies, such as vitamin D, magnesium, and omega-3 fatty acids, on the central nervous system. It provides evidence on how such insufficiencies may increase stress sensitivity and neuromuscular excitability and thereby reduce the ability to effectively respond to the overactivation of the sympathetic nervous system, and also how stress can in turn lead to these insufficiencies. Finally, the positive effects of individualized supplementation are discussed in the context of diminishing anxiety and oxidative stress, neuroprotection and in the reversal of neurodegeneration, and also in alleviating/reducing neuromuscular symptoms.
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Affiliation(s)
| | - Demetrios A. Spandidos
- Laboratory of Clinical Virology, Medical School, University of Crete, 71003 Heraklion, Greece
| | - Vassilis Zoumpourlis
- Biomedical Applications Unit, Institute of Chemical Biology, National Hellenic Research Foundation, 11635 Athens, Greece
| | - Maria Adamaki
- Biomedical Applications Unit, Institute of Chemical Biology, National Hellenic Research Foundation, 11635 Athens, Greece
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Early Life Stress (ELS) Effects on Fetal and Adult Bone Development. CHILDREN (BASEL, SWITZERLAND) 2023; 10:children10010102. [PMID: 36670652 PMCID: PMC9856960 DOI: 10.3390/children10010102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/21/2022] [Accepted: 12/30/2022] [Indexed: 01/05/2023]
Abstract
Early life stress (ELS) refers to harmful environmental events (i.e., poor maternal health, metabolic restraint, childhood trauma) occurring during the prenatal and/or postnatal period, which may cause the 'epigenetic corruption' of cellular and molecular signaling of mental and physical development. While the impact of ELS in a wide range of human diseases has been confirmed, the ELS susceptibility to bone diseases has been poorly explored. In this review, to understand the potential mediating pathways of ELS in bone diseases, PRISMA criteria were used to analyze different stress protocols in mammal models and the effects elicited in dams and their progeny. Data collected, despite the methodological heterogeneity, show that ELS interferes with fetal bone formation, also revealing that the stress type and affected developmental phase may influence the variety and severity of bone anomalies. Interestingly, these findings highlight the maternal and fetal ability to buffer stress, establishing a new role for the placenta in minimizing ELS perturbations. The functional link between ELS and bone impairments will boost future investigations on maternal stress transmission to the fetus and, parallelly, help the assessment of catch-up mechanisms of skeleton adaptations from the cascading ELS effects.
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Ng JS, Chin KY. Potential mechanisms linking psychological stress to bone health. Int J Med Sci 2021; 18:604-614. [PMID: 33437195 PMCID: PMC7797546 DOI: 10.7150/ijms.50680] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 11/30/2020] [Indexed: 02/06/2023] Open
Abstract
Chronic psychological stress affects many body systems, including the skeleton, through various mechanisms. This review aims to provide an overview of the factors mediating the relationship between psychological stress and bone health. These factors can be divided into physiological and behavioural changes induced by psychological stress. The physiological factors involve endocrinological changes, such as increased glucocorticoids, prolactin, leptin and parathyroid hormone levels and reduced gonadal hormones. Low-grade inflammation and hyperactivation of the sympathetic nervous system during psychological stress are also physiological changes detrimental to bone health. The behavioural changes during mental stress, such as altered dietary pattern, cigarette smoking, alcoholism and physical inactivity, also threaten the skeletal system. Psychological stress may be partly responsible for epigenetic regulation of skeletal development. It may also mediate the relationship between socioeconomic status and bone health. However, more direct evidence is required to prove these hypotheses. In conclusion, chronic psychological stress should be recognised as a risk factor of osteoporosis and stress-coping methods should be incorporated as part of the comprehensive osteoporosis-preventing strategy.
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Affiliation(s)
- Jia-Sheng Ng
- Department of Pharmacology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras 56000, Malaysia
| | - Kok-Yong Chin
- Department of Pharmacology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras 56000, Malaysia
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Kubo KY, Suzuki A, Iinuma M, Sato Y, Nagashio R, Ohta E, Azuma K. Vulnerability to stress in mouse offspring is ameliorated when pregnant dams are provided a chewing stick during prenatal stress. Arch Oral Biol 2018; 97:150-155. [PMID: 30390464 DOI: 10.1016/j.archoralbio.2018.10.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 10/14/2018] [Accepted: 10/15/2018] [Indexed: 12/20/2022]
Abstract
OBJECTIVE To investigate whether maternal chewing during prenatal stress alters the responsivity of young offspring to novel stress, we examined the expression of hippocampal glucocorticoid receptors and mineralocorticoid receptors, and the levels of hypothalamic corticotropin-releasing hormone in young adult mouse offspring of dams exposed to restraint stress during pregnancy. DESIGN To induce stress, the dams were placed in a ventilated restraint tube for 45 min each day from day 12 of pregnancy through parturition. While restrained in the tube, one group of dams was provided a wooden stick for chewing. Hippocampal expression of glucocorticoid receptor and mineralocorticoid receptor messenger ribonucleic acid was assessed in 1-month-old pups. Hypothalamic expression of corticotropin-releasing hormone messenger ribonucleic acid was examined before and after exposing the offspring to a novel stressor. RESULTS Prenatal stress significantly decreased hippocampal expression of both glucocorticoid receptor and mineralocorticoid receptor messenger ribonucleic acid in the offspring, and increased the expression of corticotropin-releasing hormone messenger ribonucleic acid in the hypothalamic paraventricular nucleus in the offspring after novel stress exposure. Maternal chewing during exposure to prenatal stress attenuated the decreased hippocampal expression of both glucocorticoid receptor and mineralocorticoid receptor messenger ribonucleic acid, and the increased corticotropin-releasing hormone messenger ribonucleic acid expression in the hypothalamic paraventricular nucleus in the offspring. CONCLUSIONS Downregulation of hippocampal glucocorticoid receptor and mineralocorticoid receptor expression in offspring due to prenatal stress, which may be associated with increased susceptibility to novel stress in adulthood, are attenuated by allowing the dams to chew on a wooden stick.
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Affiliation(s)
- Kin-Ya Kubo
- Graduate School of Human Life Science, Nagoya Women's University, 3-40, Shioji-cho, Mizuho-ku, Nagoya, Aichi, 467-8610, Japan.
| | - Ayumi Suzuki
- Department of Pediatric Dentistry, Asahi University School of Dentistry, 1851 Hozumi, Mizuho, Gifu, 501-0296, Japan
| | - Mitsuo Iinuma
- Department of Pediatric Dentistry, Asahi University School of Dentistry, 1851 Hozumi, Mizuho, Gifu, 501-0296, Japan
| | - Yuichi Sato
- Department of Molecular Diagnostics, Kitasato University School of Allied Health Science, 1-15-1, Minamiku, Sagamihara, Kanagawa, 252-0373, Japan; R & D Center for Cell Design, Institute for Regenerative Medicine and Cell Design, Kitasato University School of Allied Health Sciences, 1-15-1, Minamiku, Sagamihara, Kanagawa, 252-0373, Japan
| | - Ryo Nagashio
- Department of Molecular Diagnostics, Kitasato University School of Allied Health Science, 1-15-1, Minamiku, Sagamihara, Kanagawa, 252-0373, Japan; R & D Center for Cell Design, Institute for Regenerative Medicine and Cell Design, Kitasato University School of Allied Health Sciences, 1-15-1, Minamiku, Sagamihara, Kanagawa, 252-0373, Japan
| | - Etsuro Ohta
- R & D Center for Cell Design, Institute for Regenerative Medicine and Cell Design, Kitasato University School of Allied Health Sciences, 1-15-1, Minamiku, Sagamihara, Kanagawa, 252-0373, Japan; Department of Immunology, Kitasato University School of Allied Health Sciences, Kitasato, 1-15-1, Minamiku, Sagamihara, Kanagawa, 252-0373, Japan
| | - Kagaku Azuma
- Department of Anatomy, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, Fukuoka, 807-8555, Japan
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Association between Mastication, the Hippocampus, and the HPA Axis: A Comprehensive Review. Int J Mol Sci 2017; 18:ijms18081687. [PMID: 28771175 PMCID: PMC5578077 DOI: 10.3390/ijms18081687] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/31/2017] [Accepted: 08/01/2017] [Indexed: 12/29/2022] Open
Abstract
Mastication is mainly involved in food intake and nutrient digestion with the aid of teeth. Mastication is also important for preserving and promoting general health, including hippocampus-dependent cognition. Both animal and human studies indicate that mastication influences hippocampal functions through the end product of the hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoid (GC). Epidemiologic studies suggest that masticatory dysfunction in aged individuals, such as that resulting from tooth loss and periodontitis, acting as a source of chronic stress, activates the HPA axis, leading to increases in circulating GCs and eventually inducing various physical and psychological diseases, such as cognitive impairment, cardiovascular disorders, and osteoporosis. Recent studies demonstrated that masticatory stimulation or chewing during stressful conditions suppresses the hyperactivity of the HPA axis via GCs and GC receptors within the hippocampus, and ameliorates chronic stress-induced hippocampus-dependent cognitive deficits. Here, we provide a comprehensive overview of current research regarding the association between mastication, the hippocampus, and HPA axis activity. We also discuss several potential molecular mechanisms involved in the interactions between mastication, hippocampal function, and HPA axis activity.
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