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Vassal M, Martins F, Monteiro B, Tambaro S, Martinez-Murillo R, Rebelo S. Emerging Pro-neurogenic Therapeutic Strategies for Neurodegenerative Diseases: A Review of Pre-clinical and Clinical Research. Mol Neurobiol 2024:10.1007/s12035-024-04246-w. [PMID: 38816676 DOI: 10.1007/s12035-024-04246-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 05/14/2024] [Indexed: 06/01/2024]
Abstract
The neuroscience community has largely accepted the notion that functional neurons can be generated from neural stem cells in the adult brain, especially in two brain regions: the subventricular zone of the lateral ventricles and the subgranular zone in the dentate gyrus of the hippocampus. However, impaired neurogenesis has been observed in some neurodegenerative diseases, particularly in Alzheimer's, Parkinson's, and Huntington's diseases, and also in Lewy Body dementia. Therefore, restoration of neurogenic function in neurodegenerative diseases emerges as a potential therapeutic strategy to counteract, or at least delay, disease progression. Considering this, the present study summarizes the different neuronal niches, provides a collection of the therapeutic potential of different pro-neurogenic strategies in pre-clinical and clinical research, providing details about their possible modes of action, to guide future research and clinical practice.
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Affiliation(s)
- Mariana Vassal
- Department of Medical Sciences, Institute of Biomedicine (iBiMED), University of Aveiro, Aveiro, Portugal
| | - Filipa Martins
- Department of Medical Sciences, Institute of Biomedicine (iBiMED), University of Aveiro, Aveiro, Portugal
| | - Bruno Monteiro
- Department of Medical Sciences, Institute of Biomedicine (iBiMED), University of Aveiro, Aveiro, Portugal
| | - Simone Tambaro
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Huddinge, Sweden
| | - Ricardo Martinez-Murillo
- Neurovascular Research Group, Department of Translational Neurobiology, Cajal Institute (CSIC), Madrid, Spain
| | - Sandra Rebelo
- Department of Medical Sciences, Institute of Biomedicine (iBiMED), University of Aveiro, Aveiro, Portugal.
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Bramantoro T, Mardiyantoro F, Irmalia WR, Kristanti RA, Nugraha AP, Noor TEBTA, Fauzi AA, Tedjosasongko U. Early Childhood Caries, Masticatory Function, Child Early Cognitive, and Psychomotor Development: A Narrative Review. Eur J Dent 2024; 18:441-447. [PMID: 38049121 PMCID: PMC11150055 DOI: 10.1055/s-0043-1774326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2023] Open
Abstract
Dental caries is known as a global public health issue that has been affecting general health apart from its painful nature. Hence, it is undeniable that caries affecting young children or known as early childhood caries, also have an effect on children's general health. One of the interesting findings about caries is that it can also affect child growth and development, specifically on their cognitive and psychomotor ability. Untreated caries are linked to cognitive development through both neural and vascular pathways, with masticatory function as the key. Meanwhile, its effect on psychomotor development might be related to nutritional intake, which might slightly decline on those with caries. This review is aimed to describe the current findings of caries effect on early child development, from masticatory disturbance to further impacts on cognitive and psychomotor development. The overall conclusion of this review is that untreated severe caries in children are potentially associated negatively with their growth and development.
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Affiliation(s)
- Taufan Bramantoro
- Department of Dental Public Health, Faculty of Dental Medicine Universitas Airlangga, Surabaya, East Java, Indonesia
| | - Fredy Mardiyantoro
- Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Brawijaya University, Malang, East Java, Indonesia
| | - Wahyuning Ratih Irmalia
- Dental Public Health & Primary Health Care Research Group, Faculty of Dental Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Risma Aprinda Kristanti
- Department of Biomedical Science, Medical Study Program, Faculty of Medicine and Health Science, UIN Maulana Malik Ibrahim Malang, Malang, East Java, Indonesia
| | - Alexander Patera Nugraha
- Department of Orthodontic, Faculty of Dental Medicine Universitas Airlangga, Surabaya, East Java, Indonesia
| | | | - Asra Al Fauzi
- Department of Neurosurgery, Faculty of Medicine Universitas Airlangga, Surabaya, East Java, Indonesia
| | - Udijanto Tedjosasongko
- Department of Pediatric Dentistry, Faculty of Dental Medicine Universitas Airlangga, Surabaya, East Java, Indonesia
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Hussain G, Akram R, Anwar H, Sajid F, Iman T, Han HS, Raza C, De Aguilar JLG. Adult neurogenesis: a real hope or a delusion? Neural Regen Res 2024; 19:6-15. [PMID: 37488837 PMCID: PMC10479850 DOI: 10.4103/1673-5374.375317] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/27/2023] [Accepted: 04/10/2023] [Indexed: 07/26/2023] Open
Abstract
Adult neurogenesis, the process of creating new neurons, involves the coordinated division, migration, and differentiation of neural stem cells. This process is restricted to neurogenic niches located in two distinct areas of the brain: the subgranular zone of the dentate gyrus of the hippocampus and the subventricular zone of the lateral ventricle, where new neurons are generated and then migrate to the olfactory bulb. Neurogenesis has been thought to occur only during the embryonic and early postnatal stages and to decline with age due to a continuous depletion of neural stem cells. Interestingly, recent years have seen tremendous progress in our understanding of adult brain neurogenesis, bridging the knowledge gap between embryonic and adult neurogenesis. Here, we discuss the current status of adult brain neurogenesis in light of what we know about neural stem cells. In this notion, we talk about the importance of intracellular signaling molecules in mobilizing endogenous neural stem cell proliferation. Based on the current understanding, we can declare that these molecules play a role in targeting neurogenesis in the mature brain. However, to achieve this goal, we need to avoid the undesired proliferation of neural stem cells by controlling the necessary checkpoints, which can lead to tumorigenesis and prove to be a curse instead of a blessing or hope.
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Affiliation(s)
- Ghulam Hussain
- Neurochemicalbiology and Genetics Laboratory (NGL), Department of Physiology, Faculty of Life Sciences, Government College University, Faisalabad, Punjab, Pakistan
| | - Rabia Akram
- Neurochemicalbiology and Genetics Laboratory (NGL), Department of Physiology, Faculty of Life Sciences, Government College University, Faisalabad, Punjab, Pakistan
| | - Haseeb Anwar
- Neurochemicalbiology and Genetics Laboratory (NGL), Department of Physiology, Faculty of Life Sciences, Government College University, Faisalabad, Punjab, Pakistan
| | - Faiqa Sajid
- Neurochemicalbiology and Genetics Laboratory (NGL), Department of Physiology, Faculty of Life Sciences, Government College University, Faisalabad, Punjab, Pakistan
| | - Tehreem Iman
- Neurochemicalbiology and Genetics Laboratory (NGL), Department of Physiology, Faculty of Life Sciences, Government College University, Faisalabad, Punjab, Pakistan
| | - Hyung Soo Han
- Department of Physiology, School of Medicine, Clinical Omics Institute, Kyungpook National University, Daegu, Korea
| | - Chand Raza
- Department of Zoology, Faculty of Chemistry and Life Sciences, Government College University, Lahore, Pakistan
| | - Jose-Luis Gonzalez De Aguilar
- INSERM, U1118, Mécanismes Centraux et Péripheriques de la Neurodégénérescence, Strasbourg, France, Université de Strasbourg, Strasbourg, France
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Al-Manei K, Jia L, Al-Manei KK, Ndanshau EL, Grigoriadis A, Kumar A. Food Hardness Modulates Behavior, Cognition, and Brain Activation: A Systematic Review of Animal and Human Studies. Nutrients 2023; 15:nu15051168. [PMID: 36904167 PMCID: PMC10005610 DOI: 10.3390/nu15051168] [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: 01/31/2023] [Revised: 02/22/2023] [Accepted: 02/23/2023] [Indexed: 03/02/2023] Open
Abstract
Food hardness is one of the dietary features that may impact brain functions. We performed a systematic review to evaluate the effect of food hardness (hard food versus soft food diet) on behavior, cognition, and brain activation in animals and humans (PROSPERO ID: CRD42021254204). The search was conducted on 29 June 2022 using Medline (Ovid), Embase, and Web of Science databases. Data were extracted, tabulated by food hardness as an intervention, and summarized by qualitative synthesis. The SYRCLE and JBI tools were used to assess the risk of bias (RoB) of individual studies. Of the 5427 studies identified, 18 animal studies and 6 human studies met the inclusion criteria and were included. The RoB assessment indicated that 61% of animal studies had unclear risks, 11% had moderate risks, and 28% had low risks. All human studies were deemed to have a low risk of bias. The majority (48%) of the animal studies showed that a hard food diet improved behavioral task performance compared to soft food diets (8%). However, 44% of studies also showed no differential effects of food hardness on behavioral tests. It was also evident that certain regions of the brain were activated in response to changes in food hardness in humans, with a positive association between chewing hard food, cognition performance, and brain function. However, variations in the methodologies of the included studies hindered the meta-analysis execution. In conclusion, our findings highlight the beneficial effects of dietary food hardness on behavior, cognition, and brain function in both animals and humans, however, this effect may depend on several factors that require further understanding of the causality.
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Affiliation(s)
- Khaled Al-Manei
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, 141 04 Huddinge, Sweden
- Division of Endodontics, Department of Restorative Dental Science, College of Dentistry, King Saud University, Riyadh 11545, Saudi Arabia
| | - Leming Jia
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, 141 04 Huddinge, Sweden
| | - Kholod Khalil Al-Manei
- Division of Endodontics, Department of Restorative Dental Science, College of Dentistry, King Saud University, Riyadh 11545, Saudi Arabia
| | | | - Anastasios Grigoriadis
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, 141 04 Huddinge, Sweden
| | - Abhishek Kumar
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, 141 04 Huddinge, Sweden
- Academic Center for Geriatric Dentistry, 112 19 Stockholm, Sweden
- Correspondence:
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Osada K, Kujirai R, Hosono A, Tsuda M, Ohata M, Ohta T, Nishimori K. Repeated exposure to kairomone-containing coffee odor improves abnormal olfactory behaviors in heterozygous oxytocin receptor knock-in mice. Front Behav Neurosci 2023; 16:983421. [PMID: 36817409 PMCID: PMC9930907 DOI: 10.3389/fnbeh.2022.983421] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 12/16/2022] [Indexed: 02/04/2023] Open
Abstract
The oxytocin receptor (OXTR) knockout mouse is a model of autism spectrum disorder, characterized by abnormalities in social and olfactory behaviors and learning. Previously, we demonstrated that OXTR plays a crucial role in regulating aversive olfactory behavior to butyric acid odor. In this study, we attempted to determine whether coffee aroma affects the abnormal olfactory behavior of OXTR-Venus knock-in heterozygous mice [heterozygous OXTR (±) mice] using a set of behavioral and molecular experiments. Four-week repeated exposures of heterozygous OXTR (±) mice to coffee odor, containing three kairomone alkylpyrazines, rescued the abnormal olfactory behaviors compared with non-exposed wild-type or heterozygous OXTR (±) mice. Increased Oxtr mRNA expression in the olfactory bulb and amygdala coincided with the rescue of abnormal olfactory behaviors. In addition, despite containing the kairomone compounds, both the wild-type and heterozygous OXTR (±) mice exhibited a preference for the coffee odor and exhibited no stress-like increase in the corticotropin-releasing hormone, instead of a kairomone-associated avoidance response. The repeated exposures to the coffee odor did not change oxytocin and estrogen synthetase/receptors as a regulator of the gonadotropic hormone. These data suggest that the rescue of abnormal olfactory behaviors in heterozygous OXTR (±) mice is due to the coffee odor exposure-induced OXTR expression.
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Affiliation(s)
- Kazumi Osada
- Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan,*Correspondence: Kazumi Osada,
| | - Riyuki Kujirai
- Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Akira Hosono
- Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Masato Tsuda
- Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Motoko Ohata
- Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Tohru Ohta
- The Research Institute of Health Science, Health Sciences University of Hokkaido, Tobetsu, Japan
| | - Katsuhiko Nishimori
- Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
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Yin DX, Toyoda H, Nozaki K, Satoh K, Katagiri A, Adachi K, Kato T, Sato H. Taste Impairments in a Parkinson’s Disease Model Featuring Intranasal Rotenone Administration in Mice. JOURNAL OF PARKINSON'S DISEASE 2022; 12:1863-1880. [PMID: 35848036 PMCID: PMC9535587 DOI: 10.3233/jpd-223273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background: Taste impairments are often accompanied by olfactory impairments in the early stage of Parkinson’s disease (PD). The development of animal models is required to elucidate the mechanisms underlying taste impairments in PD. Objective: This study was conducted to clarify whether the intranasal administration of rotenone causes taste impairments prior to motor deficits in mice. Methods: Rotenone was administrated to the right nose of mice once a day for 1 or 4 week(s). In the 1-week group, taste, olfactory, and motor function was assessed before and after a 1-week recovery period following the rotenone administration. Motor function was also continuously examined in the 4-weeks group from 0 to 5 weeks. After a behavioral test, the number of catecholamine neurons (CA-Nos) was counted in the regions responsible for taste, olfactory, and motor function. Results: taste and olfactory impairments were simultaneously observed without locomotor impairments in the 1-week group. The CA-Nos was significantly reduced in the olfactory bulb and nucleus of the solitary tract. In the 4-week group, locomotor impairments were observed from the third week, and a significant reduction in the CA-Nos was observed in the substantia nigra (SN) and ventral tegmental area (VTA) at the fifth week along with the weight loss. Conclusion: The intranasal administration of rotenone caused chemosensory and motor impairments in an administration time-period dependent manner. Since chemosensory impairments were expressed prior to the locomotor impairments followed by SN/VTA CA neurons loss, this rotenone administration model may contribute to the clarification of the prodromal symptoms of PD.
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Affiliation(s)
- Dong Xu Yin
- Department of Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - Hiroki Toyoda
- Department of Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - Kazunori Nozaki
- Division of Medical Information, Osaka University Dental Hospital, Suita, Osaka, Japan
| | - Keitaro Satoh
- Division of Pharmacology, Meikai University School of Dentistry, Sakado, Saitama, Japan
| | - Ayano Katagiri
- Department of Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - Kazunori Adachi
- Division of Pharmacology, Meikai University School of Dentistry, Sakado, Saitama, Japan
| | - Takafumi Kato
- Department of Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - Hajime Sato
- Department of Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
- Division of Pharmacology, Meikai University School of Dentistry, Sakado, Saitama, Japan
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Short high fat diet triggers reversible and region specific effects in DCX + hippocampal immature neurons of adolescent male mice. Sci Rep 2021; 11:21499. [PMID: 34728755 PMCID: PMC8563989 DOI: 10.1038/s41598-021-01059-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 10/18/2021] [Indexed: 11/26/2022] Open
Abstract
Adolescence represents a crucial period for maturation of brain structures involved in cognition. Early in life unhealthy dietary patterns are associated with inferior cognitive outcomes at later ages; conversely, healthy diet is associated with better cognitive results. In this study we analyzed the effects of a short period of hypercaloric diet on newborn hippocampal doublecortin+ (DCX) immature neurons in adolescent mice. Male mice received high fat diet (HFD) or control low fat diet (LFD) from the 5th week of age for 1 or 2 weeks, or 1 week HFD followed by 1 week LFD. After diet supply, mice were either perfused for immunohistochemical (IHC) analysis or their hippocampi were dissected for biochemical assays. Detailed morphometric analysis was performed in DCX+ cells that displayed features of immature neurons. We report that 1 week-HFD was sufficient to dramatically reduce dendritic tree complexity of DCX+ cells. This effect occurred specifically in dorsal and not ventral hippocampus and correlated with reduced BDNF expression levels in dorsal hippocampus. Both structural and biochemical changes were reversed by a return to LFD. Altogether these studies increase our current knowledge on potential consequences of hypercaloric diet on brain and in particular on dorsal hippocampal neuroplasticity.
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Qi X, Zhu Z, Plassman BL, Wu B. Dose-Response Meta-Analysis on Tooth Loss With the Risk of Cognitive Impairment and Dementia. J Am Med Dir Assoc 2021; 22:2039-2045. [PMID: 34579934 PMCID: PMC8479246 DOI: 10.1016/j.jamda.2021.05.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 05/02/2021] [Accepted: 05/03/2021] [Indexed: 12/14/2022]
Abstract
OBJECTIVES To quantify the dose-response associations between tooth loss and risk of cognitive impairment and dementia. DESIGN Longitudinal studies that examined the association between tooth loss and cognitive function were systematically searched on 6 databases through March 1, 2020. The study adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. Risk estimates were pooled using random-effects models. The dose-response associations were assessed using generalized least squares spline models. SETTING AND PARTICIPANTS Adults from community, institution, outpatient or in-hospital were included in the meta-analysis. MEASURES Cognitive impairment and dementia were defined by neuropsychological tests, diagnostic criteria, or medical records. Tooth loss was self-reported or assessed by clinical examinations. RESULTS Fourteen studies were entered into the meta-analysis, including 34,074 participants and 4689 cases with diminished cognitive function. Participants with more tooth loss had a 1.48 times higher risk of developing cognitive impairment [95% confidence interval (CI) 1.18-1.87] and 1.28 times higher risk of being diagnosed with dementia (95% CI 1.09-1.49); however, the association was nonsignificant for participants using dentures (relative risk = 1.10, 95% CI 0.90-1.11). Eight studies were included in the dose-response analysis, and data supported the use of linear models. Each additional tooth loss was associated with a 0.014 increased relative risk of cognitive impairment and 0.011 elevated relative risks of dementia. Edentulous participants faced a 1.54 times higher risk of cognitive impairment and a 1.40 times higher risk of being diagnosed with dementia. CONCLUSIONS AND IMPLICATIONS Moderate-quality evidence suggested tooth loss was independently associated with cognitive impairment and dementia; risk of diminished cognitive function increased with incremental numbers of teeth lost. Furthermore, timely prosthodontic treatment with dentures may reduce the progression of cognitive decline related to tooth loss.
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Affiliation(s)
- Xiang Qi
- Rory Meyers College of Nursing, New York University, New York, NY, USA
| | - Zheng Zhu
- School of Nursing, Fudan University, Shanghai, China; Fudan University Centre for Evidence-based Nursing: A Joanna Briggs Institute Centre of Excellence, Shanghai, China
| | | | - Bei Wu
- Rory Meyers College of Nursing, New York University, New York, NY, USA; NYU Aging Incubator, New York University, New York, NY, USA.
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Lopez-Chaichio L, Padial-Molina M, O'Valle F, Gil-Montoya JA, Catena A, Galindo-Moreno P. Oral health and healthy chewing for healthy cognitive ageing: A comprehensive narrative review. Gerodontology 2020; 38:126-135. [PMID: 33179281 DOI: 10.1111/ger.12510] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 09/11/2020] [Accepted: 10/24/2020] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Ageing leads to physiological cognitive decline that it is worsened in people with neurodegenerative diseases such as Alzheimer's disease. Despite the ongoing search for a solution to this cognitive decline, no effective remedies have been established. It has been determined that modifiable external factors, such as oral health and occlusal function, prevent cognitive decline. OBJECTIVE To analyse the primary interactions between occlusal function and cognitive functions. MAIN FINDINGS Masticatory function is related to cognitive functions. In particular, current evidence, from both animal and human studies, suggests that the activation of masticatory muscles and proper mastication, with natural teeth or dental prosthesis, induces the release of several mediators and the activation of specific brain areas. Together, they result in higher neuronal activity, neurotrophic support, blood flow and the prevention of amyloid-beta plaque formation. Thus, all the components of the masticatory system must work together in order to preserve cognitive function. CONCLUSIONS Available evidence suggests that oral and cognitive health are more interconnected than previously thought. Therefore, maintenance and adequate restoration of the whole masticatory system are important for the prevention of cognitive decline. In summary, oral and chewing health lead to healthy cognitive ageing.
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Affiliation(s)
- Lucia Lopez-Chaichio
- Department of Oral Surgery and Implant Dentistry, School of Dentistry, University of Granada, Granada, Spain
| | - Miguel Padial-Molina
- Department of Oral Surgery and Implant Dentistry, School of Dentistry, University of Granada, Granada, Spain
| | - Francisco O'Valle
- Department of Pathology and IBIMER, School of Medicine, University of Granada, Granada, Spain.,Biosanitary Institute of Granada (ibs.Granada), University of Granada, Granada, Spain
| | - Jose Antonio Gil-Montoya
- Biosanitary Institute of Granada (ibs.Granada), University of Granada, Granada, Spain.,Department of Gerodontology, School of Dentistry, University of Granada, Granada, Spain
| | - Andres Catena
- Mind, Brain and Behavior Research Center, University of Granada, Granada, Spain
| | - Pablo Galindo-Moreno
- Department of Oral Surgery and Implant Dentistry, School of Dentistry, University of Granada, Granada, Spain
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Liu YCG, Lan SJ, Hirano H, Lin LM, Hori K, Lin CS, Zwetchkenbaum S, Minakuchi S, Teng AYT. Update and review of the gerodontology prospective for 2020's: Linking the interactions of oral (hypo)-functions to health vs. systemic diseases. J Dent Sci 2020; 16:757-773. [PMID: 33854730 PMCID: PMC8025188 DOI: 10.1016/j.jds.2020.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/03/2020] [Indexed: 02/07/2023] Open
Abstract
New lines of evidence suggest that the oral-systemic medical links and oral hypo-function are progressively transcending beyond the traditional clinical signs and symptoms of oral diseases. Research into the dysbiotic microbiome, host immune/inflammatory regulations and patho-physiologic changes and subsequent adaptations through the oral-systemic measures under ageism points to pathways leading to mastication deficiency, dysphagia, signature brain activities for (neuro)-cognition circuitries, dementia and certain cancers of the digestive system as well. Therefore, the coming era of oral health-linked systemic disorders will likely reshape the future of diagnostics in oral geriatrics, treatment modalities and professional therapies in clinical disciplines. In parallel to these highlights, a recent international symposium was jointly held by the International Association of Gerontology and Geriatrics (IAGG), Japanese Society of Gerodontology (JSG), the representative of USA and Taiwan Academy of Geriatric Dentistry (TAGD) on Oct 25th, 2019. Herein, specific notes are briefly addressed and updated for a summative prospective from this symposium and the recent literature.
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Affiliation(s)
- Yen Chun G. Liu
- Center for Osteoimmunology & Biotechnology Research (COBR) and Dept. of Oral Hygiene, College of Dental Medicine, Kaohsiung Medical University (KMU), Kaohsiung, Taiwan
- Corresponding author. Dept. of Oral Hygiene & COBR, College of Dental Medicine, Kaohsiung Medical University; No. 100, Shih-Chun 1st Rd, Kaohsiung 807, Taiwan. Fax: +886 07 3223141.
| | - Shou-Jen Lan
- Dept. of Healthcare Administration, Asia University, Tai-Chung, Taiwan
| | - Hirohiko Hirano
- Research Team for Promoting Independence & Mental Health, and Dentistry & Oral Surgery, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Tokyo, Japan
| | - Li-min Lin
- Div. of Oral Pathology & Oral Maxillo-facial Radiology, School of Dentistry, Kaohsiung Medical University & KMU-Hospital, Kaohsiung, Taiwan
| | - Kazuhiro Hori
- Div. of Comprehensive Prosthodontics, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Chia-shu Lin
- Dept. of Dentistry, School of Dentistry, National Yang-Ming University, Taipei, Taiwan
| | - Samuel Zwetchkenbaum
- Rhode Island Dept. of Health, Rhode Island, USA
- School of Public Health, Brown University, Providence, RI, USA
| | - Shunsuke Minakuchi
- Gerodontology & Oral Rehabilitation, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Andy Yen-Tung Teng
- Center for Osteoimmunology & Biotechnology Research (COBR) and Dept. of Oral Hygiene, College of Dental Medicine, Kaohsiung Medical University (KMU), Kaohsiung, Taiwan
- Center for Osteoimmunology & Biotechnology Research (COBR) and School of Dentistry, College of Dental Medicine, Kaohsiung Medical University and KMU-Hospital, Kaohsiung, Taiwan
- Corresponding author. Center for Osteoimmunology and Biotechnology Research (COBR), College of Dental Medicine, Kaohsiung Medical University (KMU) & KMU-Hospital, Kaohsiung, Taiwan.
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11
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Piancino MG, Tortarolo A, Polimeni A, Bramanti E, Bramanti P. Altered mastication adversely impacts morpho-functional features of the hippocampus: A systematic review on animal studies in three different experimental conditions involving the masticatory function. PLoS One 2020; 15:e0237872. [PMID: 32817680 PMCID: PMC7446800 DOI: 10.1371/journal.pone.0237872] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Accepted: 08/04/2020] [Indexed: 02/06/2023] Open
Abstract
Recent results have established that masticatory function plays a role not only in the balance of the stomatognathic system and in the central motor control, but also in the trophism of the hippocampus and in the cognitive activity. These implications have been shown in clinical studies and in animal researches as well, by means of histological, biochemical and behavioural techniques. This systematic review describes the effects of three forms of experimentally altered mastication, namely soft-diet feeding, molar extraction and bite-raising, on the trophism and function of the hippocampus in animal models. Through a systematic search of PubMed, Embase, Web of Science, Scopus, OpenGray and GrayMatters, 645 articles were identified, 33 full text articles were assessed for eligibility and 28 articles were included in the review process. The comprehensiveness of reporting was evaluated with the ARRIVE guidelines and the risk of bias with the SYRCLE RoB tool. The literature reviewed agrees that a disturbed mastication is significantly associated with a reduced number of hippocampal pyramidal neurons in Cornu Ammonis (CA)1 and CA3, downregulation of Brain Derived Neurotrophic Factor (BDNF), reduced synaptic activity, reduced neurogenesis in the Dentate Gyrus (DG), glial proliferation, and reduced performances in behavioural tests, indicating memory impairment and reduced spatial orientation. Moreover, while the bite-raised condition, characterized by occlusal instability, is known to be a source of stress, soft-diet feeding and molar extractions were not consistently associated with a stress response. More research is needed to clarify this topic. The emerging role of chewing in the preservation of hippocampal trophism, neurogenesis and synaptic activity is worthy of interest and may contribute to the study of neurodegenerative diseases in new and potentially relevant ways.
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Affiliation(s)
- Maria Grazia Piancino
- Department of Surgical Sciences, Dental School, University of Turin, Turin, Italy
- * E-mail:
| | - Alessandro Tortarolo
- Department of Surgical Sciences, Dental School, University of Turin, Turin, Italy
| | - Antonella Polimeni
- Department of Oral and Maxillo-Facial Science, Sapienza University of Rome, Rome, Italy
| | - Ennio Bramanti
- Department of Biomedical and Dental Sciences, Morphological and Functional Images, University of Messina, Messina, Italy
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Kouremenou I, Piper M, Zalucki O. Adult Neurogenesis in the Olfactory System: Improving Performance for Difficult Discrimination Tasks? Bioessays 2020; 42:e2000065. [PMID: 32767425 DOI: 10.1002/bies.202000065] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 07/17/2020] [Indexed: 02/04/2023]
Abstract
What is the function of new neurons entering the olfactory bulb? Many insights regarding the molecular control of adult neurogenesis have been uncovered, but the purpose of new neurons entering the olfactory bulb has been difficult to ascertain. Here, studies investigating the role of adult neurogenesis in olfactory discrimination in mice are reviewed. Studies in which adult neurogenesis is affected are highlighted, with a focus on the role of environment enrichment and what happens during ageing. There is evidence for a role of adult neurogenesis in fine discrimination tasks, as underscored by studies that enhance adult neurogenesis. This is also observed in ageing studies, where older mice with reduced levels of adult neurogenesis perform poorly in olfactory discrimination. Differences in methodology that could account for alternative conclusions, and the importance of specificity in methods being used to investigate the effect of adult neurogenesis in olfactory performance are emphasized.
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Affiliation(s)
- Ioanna Kouremenou
- The School of Biomedical Sciences, The University of Queensland, Brisbane, 4072, Australia
| | - Michael Piper
- The School of Biomedical Sciences, The University of Queensland, Brisbane, 4072, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, 4072, Australia
| | - Oressia Zalucki
- The School of Biomedical Sciences, The University of Queensland, Brisbane, 4072, Australia
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Neuroinflammation and Neurogenesis in Alzheimer's Disease and Potential Therapeutic Approaches. Int J Mol Sci 2020; 21:ijms21030701. [PMID: 31973106 PMCID: PMC7037892 DOI: 10.3390/ijms21030701] [Citation(s) in RCA: 105] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 01/17/2020] [Accepted: 01/19/2020] [Indexed: 12/17/2022] Open
Abstract
In adult brain, new neurons are generated throughout adulthood in the subventricular zone and the dentate gyrus; this process is commonly known as adult neurogenesis. The regulation or modulation of adult neurogenesis includes various intrinsic pathways (signal transduction pathway and epigenetic or genetic modulation pathways) or extrinsic pathways (metabolic growth factor modulation, vascular, and immune system pathways). Altered neurogenesis has been identified in Alzheimer's disease (AD), in both human AD brains and AD rodent models. The exact mechanism of the dysregulation of adult neurogenesis in AD has not been completely elucidated. However, neuroinflammation has been demonstrated to alter adult neurogenesis. The presence of various inflammatory components, such as immune cells, cytokines, or chemokines, plays a role in regulating the survival, proliferation, and maturation of neural stem cells. Neuroinflammation has also been considered as a hallmark neuropathological feature of AD. In this review, we summarize current, state-of-the art perspectives on adult neurogenesis, neuroinflammation, and the relationship between these two phenomena in AD. Furthermore, we discuss the potential therapeutic approaches, focusing on the anti-inflammatory and proneurogenic interventions that have been reported in this field.
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Sunariani J, Khoswanto C, Irmalia WR. Difference of brain-derived neurotrophic factor expression and pyramid cell count during mastication of food with varying hardness. J Appl Oral Sci 2019; 27:e20180182. [PMID: 30970112 PMCID: PMC6442831 DOI: 10.1590/1678-7757-2018-0182] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 09/26/2018] [Indexed: 02/02/2023] Open
Abstract
Previous studies suggested that mastication activity can affect learning and memory function. However, most were focused on mastication impaired models by providing long-term soft diet. The effects of chewing food with various hardness, especially during the growth period, remain unknown. OBJECTIVE To analyze the difference of hippocampus function and morphology, as characterized by pyramidal cell count and BDNF expression in different mastication activities. MATERIALS AND METHODS 28-day old, post-weaned, male-Wistar rats were randomly divided into three groups (n=7); the first (K0) was fed a standard diet using pellets as the control, the second (K1) was fed soft food and the third (K2) was fed hard food. After eight weeks, the rats were decapitated, their brains were removed and placed on histological plates made to count the pyramid cells and quantify BDNF expression in the hippocampus. Data collected were compared using one-way ANOVA. RESULTS Results confirmed the pyramid cell count (K0=169.14±27.25; K1=130.14±29.32; K2=128.14±39.02) and BDNF expression (K0=85.27±19.78; K1=49.57±20.90; K2=36.86±28.97) of the K0 group to be significantly higher than that of K1 and K2 groups (p<0.05); no significant difference in the pyramidal cell count and BNDF expression was found between K1 and K2 groups (p>0.05). CONCLUSION A standard diet leads to the optimum effect on hippocampus morphology. Food consistency must be appropriately suited to each development stage, in this case, hippocampus development in post-weaned period.
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Affiliation(s)
- Jenny Sunariani
- Universitas Airlangga, Faculty of Dental Medicine, Department of Oral Biology, Surabaya, Indonesia
| | - Christian Khoswanto
- Universitas Airlangga, Faculty of Dental Medicine, Department of Oral Biology, Surabaya, Indonesia
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15
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de Siqueira Mendes FDCC, da Paixão LTVB, Diniz CWP, Sosthenes MCK. Environmental Impoverishment, Aging, and Reduction in Mastication Affect Mouse Innate Repertoire to Explore Novel Environments and to Assess Risk. Front Neurosci 2019; 13:107. [PMID: 30930726 PMCID: PMC6427831 DOI: 10.3389/fnins.2019.00107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 01/29/2019] [Indexed: 12/20/2022] Open
Abstract
Studies indicate that inhibition of adequate masticatory function, due to soft diet, occlusal disharmony, or molar losses affects the cognitive behavior of rodents. However, no study has tested the effects on new environments exploration and risk assessment coupled with a combination of masticatory function rehabilitation and environmental enrichment. In the present report, we tested the hypothesis that age, environment, and masticatory changes may interact and alter exploratory patterns of locomotor activity and mice preferences in an open field (OF) arena. As OF arenas are widely used to measure anxiety-like behavior in rats and mice. We examined in an open arena, the exploratory and locomotor activities of mature (6-month-old; 6M), late mature (12-month-old; 12M), and aged (18-month-old; 18M) mice, subjected to distinct masticatory regimens and environments. Three different regimens of masticatory activity were used: continuous normal mastication with hard pellets (HD); normal mastication followed by reduced mastication with equal periods of pellets followed by soft powder – HD/SD; or rehabilitated masticatory activity with equal periods of HD, followed by powder, followed by pellets – HD/SD/HD). Under each diet regimen, half of the individuals were raised in standard cages [impoverished environment (IE)] and the other half in enriched cages [enriched environment (EE)]. Animals behavior on the open field (OF) task were recorded by webcam and analyzed with Any Maze software (Stöelting). The locomotor and exploratory activities in OF task declined with age, and this was particularly evident in 18M HD EE mice. Although all groups kept their preference by the peripheral zone, the outcomes were significantly influenced by interactions between environment, age, and diet. Independent of diet regime, 6M young mice maintained in an EE where voluntary exercise apparatus is available, revealed significant less body weight than all other groups. Although body weight differences were minimized as age progressed, 18M EE group revealed intragroup significant influence of diet regimens. We suggest that long life environmental enrichment reduces the tendency to avoid open/lit spaces (OF) and this is particularly influenced by masticatory activity. These measurements may be useful in discussions of anxiety-related tasks.
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Affiliation(s)
- Fabíola de Carvalho Chaves de Siqueira Mendes
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil.,Curso de Medicina, Centro Universitário do Estado do Pará, Belém, Brazil
| | - Luisa Taynah Vasconcelos Barbosa da Paixão
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| | - Cristovam Wanderley Picanço Diniz
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| | - Marcia Consentino Kronka Sosthenes
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
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Osada K, Ohta T, Takai R, Miyazono S, Kashiwayanagi M, Hidema S, Nishimori K. Oxytocin receptor signaling contributes to olfactory avoidance behavior induced by an unpleasant odorant. Biol Open 2018; 7:bio.029140. [PMID: 29945877 PMCID: PMC6176940 DOI: 10.1242/bio.029140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Oxytocin (OXT) and its receptor (OXTR) regulate reproductive physiology (i.e. parturition and lactation), sociosexual behavior, learned patterns of behavior and olfactory behavior in social contexts. To characterize the function of OXTR in basic olfactory behavior, the present study compared the behavioral responses of homozygous, heterozygous and wild-type mice when these mice were confronted with an unpleasant odorant (butyric acid) in a custom-made Y-maze in the absence of a social context. Wild-type mice avoided the first encounter with the butyric acid odorant, whereas homozygous and heterozygous mice did not. However, both heterozygous and wild-type mice habituated when confronted with the butyric odorant again on the following 2 days. By contrast, homozygous mice failed to habituate and instead avoided the location of the odorant for at least 3 days. These data suggest that homozygous and heterozygous mice display abnormal olfactory responses to the presentation of an unpleasant odorant. Our studies demonstrate that OXTR plays a critical role in regulating olfactory behavior in the absence of a social context. Summary: Homozygous mice exhibited abnormal olfactory behaviors, namely failure in the acute avoidance of butyric acid and in habituation behavior, in the absence of a social context.
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Affiliation(s)
- Kazumi Osada
- Division of Physiology, Department of Oral Biology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan
| | - Tohru Ohta
- The Research Institute of Health Science, Health Science University of Hokkaido, Ishikari-Tobetsu, Japan
| | - Rie Takai
- The Research Institute of Health Science, Health Science University of Hokkaido, Ishikari-Tobetsu, Japan
| | - Sadaharu Miyazono
- Department of Sensory Physiology, Asahikawa Medical University, Asahikawa, Hokkaido, Japan
| | - Makoto Kashiwayanagi
- Department of Sensory Physiology, Asahikawa Medical University, Asahikawa, Hokkaido, Japan
| | - Shizu Hidema
- Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, Miyagi, Japan
| | - Katsuhiko Nishimori
- Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, Miyagi, Japan
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17
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Leon M, Woo C. Environmental Enrichment and Successful Aging. Front Behav Neurosci 2018; 12:155. [PMID: 30083097 PMCID: PMC6065351 DOI: 10.3389/fnbeh.2018.00155] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 07/04/2018] [Indexed: 12/18/2022] Open
Abstract
The human brain sustains a slow but progressive decline in function as it ages and these changes are particularly profound in cognitive processing. A potential contributor to this deterioration is the gradual decline in the functioning of multiple sensory systems and the effects they have on areas of the brain that mediate cognitive function. In older adults, diminished capacity is typically observed in the visual, auditory, masticatory, olfactory, and motor systems, and these age-related declines are associated with both a decline in cognitive proficiency, and a loss of neurons in regions of the brain. We will review how the loss of hearing, vision, mastication skills, olfactory impairment, and motoric decline accompany cognitive loss, and how improved functioning of these systems may aid in the restoration of the cognitive abilities in older adults. The human brain appears to require a great deal of stimulation to maintain its cognitive efficacy as people age and environmental enrichment may aid in its maintenance and recovery.
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Affiliation(s)
- Michael Leon
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Cynthia Woo
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
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18
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Jou YT. Dental deafferentation and brain damage: A review and a hypothesis. Kaohsiung J Med Sci 2018; 34:231-237. [PMID: 29655412 DOI: 10.1016/j.kjms.2018.01.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/07/2017] [Accepted: 01/12/2018] [Indexed: 01/04/2023] Open
Abstract
In the last few decades, neurobiological and human brain imaging research have greatly advanced our understanding of brain mechanisms that support perception and memory, as well as their function in daily activities. Knowledge of the neurobiological mechanisms behind the deafferentation of stomatognathic systems has also expanded greatly in recent decades. In particular, current studies reveal that the peripheral deafferentations of stomatognathic systems may be projected globally into the central nervous system (CNS) and become an associated critical factor in triggering and aggravating neurodegenerative diseases. This review explores basic neurobiological mechanisms associated with the deafferentation of stomatognathic systems. Further included is a discussion on tooth loss and other dental deafferentation (DD) mechanisms, with a focus on dental and masticatory apparatuses associated with brain functions and which may underlie the changes observed in the aging brain. A new hypothesis is presented where DD and changes in the functionality of teeth and the masticatory apparatus may cause brain damage as a result of altered cerebral circulation and dysfunctional homeostasis. Furthermore, multiple recurrent reorganizations of the brain may be a triggering or contributing risk factor in the onset and progression of neurodegenerative conditions such as Alzheimer's disease (AD). A growing understanding of the association between DD and brain aging may lead to solutions in treating and preventing cognitive decline and neurodegenerative diseases.
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Affiliation(s)
- Yi-Tai Jou
- Department of Endodontics School of Dental Medicine University of Pennsylvania Philadelphia, Pennsylvania, USA.
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19
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Ogawa M, Nagai T, Saito Y, Miyaguchi H, Kumakura K, Abe K, Asakura T. Short-term mastication after weaning upregulates GABAergic signalling and reduces dendritic spine in thalamus. Biochem Biophys Res Commun 2018. [DOI: 10.1016/j.bbrc.2018.03.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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20
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Liang Y, Chen J, Zheng X, Chen Z, Liu Y, Li S, Fang X. Ultrasound-Mediated Kallidinogenase-Loaded Microbubble Targeted Therapy for Acute Cerebral Infarction. J Stroke Cerebrovasc Dis 2018; 27:686-696. [DOI: 10.1016/j.jstrokecerebrovasdis.2017.09.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 08/24/2017] [Accepted: 09/29/2017] [Indexed: 10/18/2022] Open
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21
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Shohayeb B, Diab M, Ahmed M, Ng DCH. Factors that influence adult neurogenesis as potential therapy. Transl Neurodegener 2018; 7:4. [PMID: 29484176 PMCID: PMC5822640 DOI: 10.1186/s40035-018-0109-9] [Citation(s) in RCA: 122] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 02/16/2018] [Indexed: 12/21/2022] Open
Abstract
Adult neurogenesis involves persistent proliferative neuroprogenitor populations that reside within distinct regions of the brain. This phenomenon was first described over 50 years ago and it is now firmly established that new neurons are continually generated in distinct regions of the adult brain. The potential of enhancing the neurogenic process lies in improved brain cognition and neuronal plasticity particularly in the context of neuronal injury and neurodegenerative disorders. In addition, adult neurogenesis might also play a role in mood and affective disorders. The factors that regulate adult neurogenesis have been broadly studied. However, the underlying molecular mechanisms of regulating neurogenesis are still not fully defined. In this review, we will provide critical analysis of our current understanding of the factors and molecular mechanisms that determine neurogenesis. We will further discuss pre-clinical and clinical studies that have investigated the potential of modulating neurogenesis as therapeutic intervention in neurodegeneration.
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Affiliation(s)
- Belal Shohayeb
- 1School of Biomedical Science, Faculty of Medicine, University of Queensland, St Lucia, QLD 4067 Australia
| | - Mohamed Diab
- 2Faculty of Pharmacy, Pharos University in Alexandria, P.O. Box Sidi Gaber, Alexandria, 21311 Egypt
| | - Mazen Ahmed
- 2Faculty of Pharmacy, Pharos University in Alexandria, P.O. Box Sidi Gaber, Alexandria, 21311 Egypt
| | - Dominic Chi Hiung Ng
- 1School of Biomedical Science, Faculty of Medicine, University of Queensland, St Lucia, QLD 4067 Australia
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22
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Etizolam attenuates the reduction in cutaneous temperature induced in mice by exposure to synthetic predator odor. Eur J Pharmacol 2018; 824:157-162. [PMID: 29438703 DOI: 10.1016/j.ejphar.2018.02.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Revised: 02/08/2018] [Accepted: 02/09/2018] [Indexed: 12/30/2022]
Abstract
Anxiety- and stress-related disorders can be debilitating psychiatric conditions in humans. To prevent or ameliorate these conditions, reliable animal models are needed to evaluate the effects of anxiolytic drugs. Previously, we found that a mixture of three pyrazine analogues (P-mix) that were present at high levels in wolf urine induced fear-related responses in mice, rats and deer. A change in cutaneous temperature was shown to be induced by acute stress simultaneously with changes in heart rate, arterial pressure and freezing behavior, raising the possibility that cutaneous temperature could be used as an index of stress. In the present study, using infrared thermography, we showed that exposure of mice to P-mix induced a decrease in cutaneous temperature. We then examined the dose-dependent effects of an anxiolytic drug, etizolam (0-20 mg/kg), on the temperature decrease. Pre-administration of etizolam (5 mg/kg or higher) inhibited the P-mix-induced decrease in cutaneous temperature. Exposure to P-mix induced Fos-immunoreactivity, a marker of neuronal excitation, at the mouse amygdala and hypothalamus, and etizolam (5 mg/kg) attenuated that immunoreactivity. The present results suggested that the measurement of cutaneous P-mix-induced temperature changes in mice could be used as an animal model for evaluating the effects of anxiolytic drugs.
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23
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Koskinen K, Reichert JL, Hoier S, Schachenreiter J, Duller S, Moissl-Eichinger C, Schöpf V. The nasal microbiome mirrors and potentially shapes olfactory function. Sci Rep 2018; 8:1296. [PMID: 29358754 PMCID: PMC5778015 DOI: 10.1038/s41598-018-19438-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 12/29/2017] [Indexed: 02/07/2023] Open
Abstract
Olfactory function is a key sense for human well-being and health, with olfactory dysfunction having been linked to serious diseases. As the microbiome is involved in normal olfactory epithelium development, we explored the relationship between olfactory function (odor threshold, discrimination, identification) and nasal microbiome in 67 healthy volunteers. Twenty-eight subjects were found to have normal olfactory function, 29 had a particularly good sense of smell ("good normosmics") and 10 were hyposmic. Microbial community composition differed significantly between the three olfactory groups. In particular, butyric acid-producing microorganisms were found to be associated with impaired olfactory function. We describe the first insights of the potential interplay between the olfactory epithelium microbial community and olfactory function, and suggest that the microbiome composition is able to mirror and potentially shape olfactory function by producing strong odor compounds.
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Affiliation(s)
- Kaisa Koskinen
- Department of Internal Medicine, Medical University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Johanna L Reichert
- BioTechMed-Graz, Graz, Austria
- Institute of Psychology, University of Graz, Graz, Austria
| | - Stefan Hoier
- Hanusch Krankenhaus Vienna, Department of Otorhinolaryngology, Head and Neck Surgery, Vienna, Austria
| | | | - Stefanie Duller
- Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - Christine Moissl-Eichinger
- Department of Internal Medicine, Medical University of Graz, Graz, Austria.
- BioTechMed-Graz, Graz, Austria.
| | - Veronika Schöpf
- BioTechMed-Graz, Graz, Austria.
- Institute of Psychology, University of Graz, Graz, Austria.
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Kumar A, Kothari M, Grigoriadis A, Trulsson M, Svensson P. Bite or brain: Implication of sensorimotor regulation and neuroplasticity in oral rehabilitation procedures. J Oral Rehabil 2018; 45:323-333. [DOI: 10.1111/joor.12603] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2017] [Indexed: 02/04/2023]
Affiliation(s)
- A. Kumar
- Division of Oral Diagnostics and Rehabilitation; Department of Dental Medicine; Karolinska Institutet; Huddinge Sweden
- Scandinavian Center for Orofacial Neurosciences (SCON); Huddinge Sweden
| | - M. Kothari
- Hammel Neurorehabilitation Centre and University Research Clinic; Aarhus University; Hammel Denmark
| | - A. Grigoriadis
- Division of Oral Diagnostics and Rehabilitation; Department of Dental Medicine; Karolinska Institutet; Huddinge Sweden
- Scandinavian Center for Orofacial Neurosciences (SCON); Huddinge Sweden
| | - M. Trulsson
- Division of Oral Diagnostics and Rehabilitation; Department of Dental Medicine; Karolinska Institutet; Huddinge Sweden
- Scandinavian Center for Orofacial Neurosciences (SCON); Huddinge Sweden
| | - P. Svensson
- Division of Oral Diagnostics and Rehabilitation; Department of Dental Medicine; Karolinska Institutet; Huddinge Sweden
- Scandinavian Center for Orofacial Neurosciences (SCON); Huddinge Sweden
- Section of Orofacial Pain and Jaw Function; Institute for Odontology and Oral Health; Aarhus University; Aarhus Denmark
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25
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Lin CS. Revisiting the link between cognitive decline and masticatory dysfunction. BMC Geriatr 2018; 18:5. [PMID: 29304748 PMCID: PMC5756393 DOI: 10.1186/s12877-017-0693-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 12/18/2017] [Indexed: 12/17/2022] Open
Abstract
Age-related decline in cognitive functions and dementia are major challenges in geriatric healthcare. Accumulating evidence from clinical, epidemiological and animal research suggests that tooth loss may be a risk factor for the decline of cognitive functions. This issue highlights the role of the brain-stomatognathic axis in geriatric medicine. Whether input from the stomatognathic apparatus can affect the brain remains an open debate. By revisiting the evidence published in the past five years, we argue that the hypothesis regarding the association between cognitive decline and masticatory dysfunction should be carefully interpreted. Most of the available clinical and epidemiological studies present only cross-sectional data. With respect to the prospective studies, important confounding factors, such as nutritional and physical conditions, were not fully controlled for. Animal research has revealed that hippocampal deficits may play key roles in the observed cognitive decline. However, experimental intervention and outcome assessments may not capture the condition of human subjects. Brain neuroimaging research may be suitable for bridging the gap between clinical and animal research, potentially contributing to (a) the clarification of the brain network associated with mastication, (b) the identification of brain imaging markers for exploring the mechanisms underlying long-term changes in masticatory functions, and (c) the elucidation of interactions between mastication and other cognitive-affective processing systems. Three potential models of the brain-stomatognathic axis and relevant hypotheses are summarized, focusing on the sensory feedback mechanisms, the compensation of motor control, and cerebellar deficits. Finally, we highlight four critical aspects of study and experimental design that should be considered in future research: (a) the refinement of the considered behavioral assessments, (b) the inclusion of baseline changes in mental and physical conditions,
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Affiliation(s)
- Chia-Shu Lin
- Department of Dentistry, School of Dentistry, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei, 11221, Taiwan.
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Rodriguez RL, Albeck JG, Taha AY, Ori-McKenney KM, Recanzone GH, Stradleigh TW, Hernandez BC, Tang FYV, Chiang EPI, Cruz-Orengo L. Impact of diet-derived signaling molecules on human cognition: exploring the food-brain axis. NPJ Sci Food 2017; 1:2. [PMID: 31304244 PMCID: PMC6548416 DOI: 10.1038/s41538-017-0002-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 08/25/2017] [Accepted: 09/01/2017] [Indexed: 01/02/2023] Open
Abstract
The processes that define mammalian physiology evolved millions of years ago in response to ancient signaling molecules, most of which were acquired by ingestion and digestion. In this way, evolution inextricably linked diet to all major physiological systems including the nervous system. The importance of diet in neurological development is well documented, although the mechanisms by which diet-derived signaling molecules (DSMs) affect cognition are poorly understood. Studies on the positive impact of nutritive and non-nutritive bioactive molecules on brain function are encouraging but lack the statistical power needed to demonstrate strong positive associations. Establishing associations between DSMs and cognitive functions like mood, memory and learning are made even more difficult by the lack of robust phenotypic markers that can be used to accurately and reproducibly measure the effects of DSMs. Lastly, it is now apparent that processes like neurogenesis and neuroplasticity are embedded within layers of interlocked signaling pathways and gene regulatory networks. Within these interdependent pathways and networks, the various transducers of DSMs are used combinatorially to produce those emergent adaptive gene expression responses needed for stimulus-induced neurogenesis and neuroplasticity. Taken together, it appears that cognition is encoded genomically and modified by epigenetics and epitranscriptomics to produce complex transcriptional programs that are exquisitely sensitive to signaling molecules from the environment. Models for how DSMs mediate the interplay between the environment and various neuronal processes are discussed in the context of the food-brain axis.
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Affiliation(s)
- Raymond L. Rodriguez
- Department of Molecular and Cellular Biology, College of Biological Sciences, One Shields Avenue, University of California, Davis, Davis, CA 95616 USA
| | - John G. Albeck
- Department of Molecular and Cellular Biology, College of Biological Sciences, One Shields Avenue, University of California, Davis, Davis, CA 95616 USA
| | - Ameer Y. Taha
- Department of Food Science and Technology, College of Agriculture and Environmental Sciences, One Shields Avenue, University of California, Davis, Davis, CA 95616 USA
| | - Kassandra M. Ori-McKenney
- Department of Molecular and Cellular Biology, College of Biological Sciences, One Shields Avenue, University of California, Davis, Davis, CA 95616 USA
| | - Gregg H. Recanzone
- Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, One Shields Avenue, University of California, Davis, Davis, CA 95616 USA
- Center for Neuroscience, College of Biological Sciences, University of California, Davis, Davis, CA 95616 USA
| | - Tyler W. Stradleigh
- Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, One Shields Avenue, University of California, Davis, Davis, CA 95616 USA
- Center for Neuroscience, College of Biological Sciences, University of California, Davis, Davis, CA 95616 USA
- Department of Psychiatry and Behavioral Sciences, School of Medicine, University of California, Davis, Davis, CA 95616 USA
| | - Bronte C. Hernandez
- Department of Molecular and Cellular Biology, College of Biological Sciences, One Shields Avenue, University of California, Davis, Davis, CA 95616 USA
| | | | - En-Pei Isabel Chiang
- Department of Food Science and Biotechnology, National Chung Hsing University, Taichung, Taiwan
- Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
| | - Lillian Cruz-Orengo
- Department of Anatomy, Physiology & Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616 USA
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27
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Kashiwayanagi M, Miyazono S, Osada K. Pyrazine analogues from wolf urine induced unlearned fear in rats. Heliyon 2017; 3:e00391. [PMID: 28920093 PMCID: PMC5585003 DOI: 10.1016/j.heliyon.2017.e00391] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 07/14/2017] [Accepted: 08/16/2017] [Indexed: 12/21/2022] Open
Abstract
Urine excreted from the common grey wolf (Canis lupus) contains a kairomone, inducing fear-related behaviors in various mammals. Numerous fear-inducing substances activate neurons at the main and/or accessory olfactory bulb (AOB), medial and central amygdala, and hypothalamus. Our previous study showed that the mixture of pyrazine analogues (P-mix) contained in wolf urine induced avoidance and fear-related behaviors in laboratory mice and Hokkaido deer (Cervus nippon yesoensis), a species native to Japan. Exposure to wolf urine or P-mix induced expression of Fos, a marker of neuronal excitation, in the AOB of mice. In the present study, we explored the effects of P-mix on fear-related behaviors and Fos-expression in rats. Exposure to P-mix induced avoidance and immobilization in rats, while that to a mixture of i-amyl acetate, linalool and R(+)-limonene (O-mix), which generate floral and fruity odors, induced avoidance but not immobilization. P-mix but not O-mix increased Fos-immunoreactivity of the AOB, medial and central amygdala, and hypothalamus of rats. The present results suggest that P-mix odor induces unlearned fear-related behaviors in rats.
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Affiliation(s)
- Makoto Kashiwayanagi
- Department of Sensory Physiology, Asahikawa Medical University, Asahikawa, Hokkaido, Japan
- Corresponding author at: Department of Sensory Physiology, Asahikawa Medical University, Midorigaoka E2-1, Asahikawa, Japan.Department of Sensory PhysiologyAsahikawa Medical UniversityAsahikawaHokkaidoJapan
| | - Sadaharu Miyazono
- Department of Sensory Physiology, Asahikawa Medical University, Asahikawa, Hokkaido, Japan
| | - Kazumi Osada
- Division of Physiology, Department of Oral Biology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan
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28
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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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29
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Eghlidospour M, Ghanbari A, Mortazavi SMJ, Azari H. Effects of radiofrequency exposure emitted from a GSM mobile phone on proliferation, differentiation, and apoptosis of neural stem cells. Anat Cell Biol 2017; 50:115-123. [PMID: 28713615 PMCID: PMC5509895 DOI: 10.5115/acb.2017.50.2.115] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 12/13/2016] [Accepted: 03/18/2017] [Indexed: 11/27/2022] Open
Abstract
Due to the importance of neural stem cells (NSCs) in plasticity of the nervous system and treating neurodegenerative diseases, the main goal of this study was to evaluate the effects of radiofrequency radiation emitted from a GSM 900-MHz mobile phone with different exposure duration on proliferation, differentiation and apoptosis of adult murine NSCs in vitro. We used neurosphere assay to evaluate NSCs proliferation, and immunofluorescence assay of neural cell markers to examine NSCs differentiation. We also employed alamarBlue and caspase 3 apoptosis assays to assess harmful effects of mobile phone on NSCs. Our results showed that the number and size of resulting neurospheres and also the percentage of cells differentiated into neurons decreased significantly with increasing exposure duration to GSM 900-MHz radiofrequency (RF)-electromagnetic field (EMF). In contrast, exposure to GSM 900-MHz RF-EMF at different durations did not influence cell viability and apoptosis of NSCs and also their astrocytic differentiation. It is concluded that accumulating dose of GSM 900-MHz RF-EMF might have devastating effects on NSCs proliferation and neurogenesis requiring more causations in terms of using mobile devices.
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Affiliation(s)
- Mahsa Eghlidospour
- Neural Stem Cell and Regenerative Neuroscience Laboratory, Department of Anatomical Sciences, Shiraz School of Medicine, Shiraz Stem Cell Institute, Shiraz University of Medical Sciences, Shiraz, Iran.,Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, Iran.,Department of Medical Physics and Medical Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Amir Ghanbari
- Department of Anatomical Sciences, Yasuj University of Medical Sciences, Yasuj, Iran
| | - Seyyed Mohammad Javad Mortazavi
- Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, Iran.,Department of Medical Physics and Medical Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Hassan Azari
- Neural Stem Cell and Regenerative Neuroscience Laboratory, Department of Anatomical Sciences, Shiraz School of Medicine, Shiraz Stem Cell Institute, Shiraz University of Medical Sciences, Shiraz, Iran
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30
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Sasajima H, Miyazono S, Noguchi T, Kashiwayanagi M. Intranasal administration of rotenone in mice attenuated olfactory functions through the lesion of dopaminergic neurons in the olfactory bulb. Neurotoxicology 2015; 51:106-15. [PMID: 26493152 DOI: 10.1016/j.neuro.2015.10.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 09/14/2015] [Accepted: 10/13/2015] [Indexed: 12/20/2022]
Abstract
Many environmental chemicals are thought to affect brain function. It was reported that chemicals in the nasal cavity directly reach the brain through the connection between olfactory neurons and the olfactory bulb (OB). In this 'olfactory transport,' xenobiotics absorbed at the nasal mucosa reach the brain by bypassing some physical barriers and defenses, and thus olfactory transport is suspected to be a vulnerable mechanism of the brain against invasion threats of environmental chemicals. In this study, we focused on the neuronal toxicity of rotenone administered intranasally to mice. The results showed that the mice that were administered rotenone had attenuated olfactory functions. We also found that intranasally administered rotenone induced acute mitochondrial stress at the OB. The repeated administration of rotenone resulted in a decrease in the number of dopaminergic neurons, which are inhibitory interneurons in the OB. Taken together, our findings suggest that the inhalation of environmental toxins induces the neurodegeneration of cranial neurons through olfactory transport, and that olfactory dysfunction may be induced as an earliest symptom of neurodegeneration caused by inhaled neurotoxins.
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Affiliation(s)
- Hitoshi Sasajima
- Department of Physiology, Division of Sensory Physiology, Asahikawa Medical University, Asahikawa, Japan
| | - Sadaharu Miyazono
- Department of Physiology, Division of Sensory Physiology, Asahikawa Medical University, Asahikawa, Japan
| | - Tomohiro Noguchi
- Department of Physiology, Division of Sensory Physiology, Asahikawa Medical University, Asahikawa, Japan
| | - Makoto Kashiwayanagi
- Department of Physiology, Division of Sensory Physiology, Asahikawa Medical University, Asahikawa, Japan.
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31
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Chen H, Iinuma M, Onozuka M, Kubo KY. Chewing Maintains Hippocampus-Dependent Cognitive Function. Int J Med Sci 2015; 12:502-9. [PMID: 26078711 PMCID: PMC4466515 DOI: 10.7150/ijms.11911] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 05/25/2015] [Indexed: 02/07/2023] Open
Abstract
Mastication (chewing) is important not only for food intake, but also for preserving and promoting the general health. Recent studies have showed that mastication helps to maintain cognitive functions in the hippocampus, a central nervous system region vital for spatial memory and learning. The purpose of this paper is to review the recent progress of the association between mastication and the hippocampus-dependent cognitive function. There are multiple neural circuits connecting the masticatory organs and the hippocampus. Both animal and human studies indicated that cognitive functioning is influenced by mastication. Masticatory dysfunction is associated with the hippocampal morphological impairments and the hippocampus-dependent spatial memory deficits, especially in elderly. Mastication is an effective behavior for maintaining the hippocampus-dependent cognitive performance, which deteriorates with aging. Therefore, chewing may represent a useful approach in preserving and promoting the hippocampus-dependent cognitive function in older people. We also discussed several possible mechanisms involved in the interaction between mastication and the hippocampal neurogenesis and the future directions for this unique fascinating research.
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Affiliation(s)
- Huayue Chen
- 1. Department of Anatomy Gifu University Graduate School of Medicine, Gifu, 501-1194, Gifu, Japan
| | - Mitsuo Iinuma
- 2. Department of Pediatric Dentistry, Division of Oral Structure, Function and Development, Asahi University, School of Dentistry, Mizuho, 501-0296, Gifu, Japan
| | - Minoru Onozuka
- 3. Department of Judo Therapy and Medical Science, Faculty of Medical Science, Nippon Sport Science University, Yokohama 227-0033, Kanagawa, Japan
| | - Kin-Ya Kubo
- 4. Seijoh University Graduate School of Health Care Studies, Tokai, 476-8588, Aichi, Japan
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32
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Utsugi C, Miyazono S, Osada K, Matsuda M, Kashiwayanagi M. Impaired mastication reduced newly generated neurons at the accessory olfactory bulb and pheromonal responses in mice. Arch Oral Biol 2014; 59:1272-8. [PMID: 25150532 DOI: 10.1016/j.archoralbio.2014.07.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 07/22/2014] [Indexed: 11/24/2022]
Abstract
OBJECTIVES A large number of neurons are generated at the subventricular zone (SVZ) even during adulthood. In a previous study, we have shown that a reduced mastication impairs both neurogenesis in the SVZ and olfactory functions. Pheromonal signals, which are received by the vomeronasal organ, provide information about reproductive and social states. Vomeronasal sensory neurons project to the accessory olfactory bulb (AOB) located on the dorso-caudal surface of the main olfactory bulb. Newly generated neurons at the SVZ migrate to the AOB and differentiate into granule cells and periglomerular cells. This study aimed to explore the effects of changes in mastication on newly generated neurons and pheromonal responses. DESIGN Bromodeoxyuridine-immunoreactive (BrdU-ir; a marker of DNA synthesis) and Fos-ir (a marker of neurons excited) structures in sagittal sections of the AOB after exposure to urinary odours were compared between the mice fed soft and hard diets. RESULTS The density of BrdU-ir cells in the AOB in the soft-diet-fed mice after 1 month was essentially similar to that of the hard-diet-fed mice, while that was lower in the soft-diet-fed mice for 3 or 6 months than in the hard-diet-fed mice. The density of Fos-ir cells in the soft-diet-fed mice after 2 months was essentially similar to that in the hard-diet-fed mice, while that was lower in the soft-diet-fed mice for 4 months than in the hard-diet-fed mice. CONCLUSIONS The present results suggest that impaired mastication reduces newly generated neurons at the AOB, which in turn impairs olfactory function at the AOB.
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Affiliation(s)
- Chizuru Utsugi
- Department of Oral and Maxillofacial Surgery, Asahikawa Medical University, Asahikawa 078-8510, Japan; Department of Sensory Physiology, Asahikawa Medical University, Asahikawa 078-8510, Japan
| | - Sadaharu Miyazono
- Department of Sensory Physiology, Asahikawa Medical University, Asahikawa 078-8510, Japan
| | - Kazumi Osada
- Department of Oral Biology, School of Dentistry, Health Sciences University of Hokkaido, Tohbetu 061-0293, Japan
| | - Mitsuyoshi Matsuda
- Department of Oral and Maxillofacial Surgery, Asahikawa Medical University, Asahikawa 078-8510, Japan
| | - Makoto Kashiwayanagi
- Department of Sensory Physiology, Asahikawa Medical University, Asahikawa 078-8510, Japan.
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