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Ichikawa-Kato T, Hara T, Yamada-Kubota C, Kuwahara M, Murakami A, Minagi S. Effects of intracerebral noradrenaline on cognitive decline associated with the loss of occlusal support. J Prosthodont Res 2024:JPR_D_23_00231. [PMID: 39198203 DOI: 10.2186/jpr.jpr_d_23_00231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2024]
Abstract
PURPOSE The lack of occlusal support reportedly reduces cognitive function; however, the underlying mechanisms remain unclear. The locus coeruleus, which is located adjacent to the trigeminal mesencephalic nucleus, secretes noradrenaline throughout the brain. In this study, we evaluated the effects of noradrenaline in the hippocampus and cerebral cortex on cognitive decline following tooth extraction in rats. METHODS We performed passive avoidance experiments on male Wistar rats with extracted maxillary molars and determined the neuron density in the locus coeruleus and trigeminal mesencephalic nucleus using immunostaining and Nissl staining, respectively. We also assessed noradrenaline concentrations in the hippocampus and cerebral cortex using enzyme-linked immunosorbent assay. RESULTS In the passive avoidance experiment, the latency in the bright compartment was significantly shorter (P < 0.05) in the extraction group than in the control group. The numbers of cells in the locus coeruleus and trigeminal nucleus were significantly lower (P < 0.05) in the extraction group compared to those in the control group. The noradrenaline levels in the hippocampus and cerebral cortex were also significantly lower (P < 0.05) in the extraction group than those in the control group. CONCLUSIONS The lack of occlusal support associated with tooth extraction reduces the number of cells in the trigeminal mesencephalic nucleus and locus coeruleus, which may reduce the supply of noradrenaline to the cerebral cortex and hippocampus, leading to a decline in cognitive function.
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Affiliation(s)
- Tomoka Ichikawa-Kato
- Department of Occlusal and Oral Functional Rehabilitation, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Tetsuya Hara
- Department of Occlusal and Oral Functional Rehabilitation, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Chie Yamada-Kubota
- Department of Occlusal and Oral Functional Rehabilitation, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Miho Kuwahara
- Department of Occlusal and Oral Functional Rehabilitation, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Asuka Murakami
- Department of Occlusal and Oral Functional Rehabilitation, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Shogo Minagi
- Department of Occlusal and Oral Functional Rehabilitation, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
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Furukawa M, Tada H, Raju R, Wang J, Yokoi H, Ikuyo Y, Yamada M, Shikama Y, Matsushita K. Long-Term Capsaicin Administration Ameliorates the Dysfunction and Astrogliosis of the Brain in Aged Mice with Missing Maxillary Molars. Nutrients 2023; 15:nu15112471. [PMID: 37299434 DOI: 10.3390/nu15112471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 05/13/2023] [Accepted: 05/22/2023] [Indexed: 06/12/2023] Open
Abstract
Tooth loss and decreased masticatory function reportedly affect cognitive function; tooth loss allegedly induces astrogliosis and aging of astrocytes in the hippocampus and hypothalamus, which is a response specific to the central nervous system owing to homeostasis in different brain regions. Capsaicin, a component of red peppers, has positive effects on brain disorders in mice. Decreased expression of transient receptor potential vanilloid 1, a receptor of capsaicin, is associated with the development of dementia. In this study, we investigated the effect of capsaicin administration in aged mice (C57BL/6N mice) with reduced masticatory function owing to the extraction of maxillary molars to investigate preventive/therapeutic methods for cognitive decline attributed to age-related masticatory function loss. The results demonstrated that mice with impaired masticatory function showed decreased motor and cognitive function at the behavioral level. At the genetic level, neuroinflammation, microglial activity, and astrogliosis, such as increased glial fibrillary acidic protein levels, were observed in the mouse brain. The mice with extracted molars fed on a diet containing capsaicin for 3 months demonstrated improved behavioral levels and astrogliosis, which suggest that capsaicin is useful in maintaining brain function in cases of poor oral function and prosthetic difficulties.
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Affiliation(s)
- Masae Furukawa
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Hirobumi Tada
- Department of Nutrition, Faculty of Wellness, Shigakkan University, Obu 474-8651, Japan
- Department of Integrative Physiology, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Resmi Raju
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Jingshu Wang
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Haruna Yokoi
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Yoriko Ikuyo
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Mitsuyoshi Yamada
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
- Department of Operative Dentistry, School of Dentistry, Aichi Gakuin University, Nagoya 464-8651, Japan
| | - Yosuke Shikama
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Kenji Matsushita
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
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Furukawa M, Tada H, Wang J, Yamada M, Kurosawa M, Satoh A, Ogiso N, Shikama Y, Matsushita K. Molar loss induces hypothalamic and hippocampal astrogliosis in aged mice. Sci Rep 2022; 12:6409. [PMID: 35437315 PMCID: PMC9016068 DOI: 10.1038/s41598-022-10321-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 04/05/2022] [Indexed: 11/09/2022] Open
Abstract
Age-related tooth loss impedes mastication. Epidemiological and physiological studies have reported that poor oral hygiene and occlusion are associated with cognitive decline. In the present study, we analyzed the mechanism by which decreased occlusal support following bilateral extraction of the maxillary first molars affects cognitive functions in young and aged mice and examined the expression of brain-function-related genes in the hippocampus and hypothalamus. We observed decreased working memory, enhanced restlessness, and increased nocturnal activity in aged mice with molar extraction compared with that in mice with intact molars. Furthermore, in the hypothalamus and hippocampus of molar-extracted aged mice, the transcript-level expression of Bdnf, Rbfox3, and Fos decreased, while that of Cdkn2a and Aif1 increased. Thus, decreased occlusal support after maxillary first molar extraction may affect cognitive function and activity in mice by influencing aging, neural activity, and neuroinflammation in the hippocampus and hypothalamus.
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Affiliation(s)
- Masae Furukawa
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan.
| | - Hirobumi Tada
- Department of Nutrition, Faculty of Wellness, Shigakkan University, Obu, Japan.,Department of Inflammation and Immunosenescence, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Jingshu Wang
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Mitsuyoshi Yamada
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan.,Department of Operative Dentistry, School of Dentistry, Aichi Gakuin University, Nagoya, Japan
| | - Mie Kurosawa
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Akiko Satoh
- Department of Integrative Physiology, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan.,Department of Integrative Physiology, Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan
| | - Noboru Ogiso
- Department of Laboratory of Experimental Animals, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Yosuke Shikama
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Kenji Matsushita
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan.
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4
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Murakami A, Hara T, Yamada-Kubota C, Kuwahara M, Ichikawa T, Minagi S. Lack of occlusal support did not impact amyloid β deposition in APP knock-in mice. J Prosthodont Res 2021; 66:161-166. [PMID: 34305086 DOI: 10.2186/jpr.jpr_d_20_00205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
PURPOSE The lack of occlusal support is an epidemiological risk factor linked to Alzheimer's disease. This study sought to assess the relationship between amyloid β (Aβ) deposition and the lack of occlusal support in amyloid precursor protein (APP) knock-in mice. METHODS Sixteen experimental animals were divided into two groups. The upper molars were extracted in the extraction group (group E), and a sham operation was performed in the control group (group C). The Morris water maze test was performed 4 months after the tooth extraction. Aβ immunohistochemical staining and Nissl staining of the hippocampus were performed. Hippocampal plasma corticosterone and Aβ protein levels were measured. RESULTS In the maze task, the escape latency was significantly longer in group E than in group C. In the probe trials, the time elapsed in the target quadrant was significantly shorter in group E than in group C. The number of hippocampal neurons decreased in group E. There was no significant difference in the plasma corticosterone levels between the two groups, indicating that there was no effect of chronic stress on the behavioral results. Hippocampal Aβ40 and Aβ42 protein levels and Aβ deposition areas by immunohistochemical staining were not significantly different between the two groups. CONCLUSIONS Aβ deposition was not increased in the hippocampus of molarless APP knock-in mice. As such, it appears that cognitive impairment due to a lack of occlusal support was not related to Aβ deposition.
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Affiliation(s)
- Asuka Murakami
- Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University
| | - Tetsuya Hara
- Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University
| | - Chie Yamada-Kubota
- Department of Occlusion and Removable Prosthodontics, Okayama University Hospital
| | - Miho Kuwahara
- Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University
| | - Tomoka Ichikawa
- Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University
| | - Shogo Minagi
- Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University
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5
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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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6
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Zhang L, Fan Y, Kong X, Hao W. Neuroprotective effect of different physical exercises on cognition and behavior function by dopamine and 5-HT level in rats of vascular dementia. Behav Brain Res 2020; 388:112648. [PMID: 32339549 DOI: 10.1016/j.bbr.2020.112648] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 03/21/2020] [Accepted: 04/07/2020] [Indexed: 12/27/2022]
Abstract
The aim of the present study is to evaluate neuroprotective effect of different physical exercises on cognition and behavior function by dopamine and 5-HT in rats of vascular dementia. Forty Sprague-Dawley rats were enrolled in this study and randomly divided into following 5 groups: control group (C group, n = 8), vascular dementia group (VD group, n = 8), treadmill exercise and vascular dementia group (TE-VD group, n = 8), in-voluntary exercise and vascular dementia group (IE-VD group, n = 8), voluntary exercise and vascular dementia group (VE-VD group, n = 8). The rats in TE-VD, IE-VD and VE-VD groups were received different physical exercise interventions, treadmill exercise, voluntary running exercise, involuntary running exercise respectively, total 4 weeks. Next, the rats in VE-VD, IE-VD, TE-VD and VD groups were received bilateral common carotids arteries operation to create vascular dementia model. Then, we use a passive avoid test to evaluate cognition and open field test to evaluate cognition autonomic activity in each group. The level in hippocampal dopamine and 5-HT were detected by microdialysis coupled with high performance liquid chromatography. Behavior results demonstrated that: compared with C group, the cognition in VD group significantly decreased (p < 0.001); compared with VD group, the cognition in VE-VD, IE-VD and TE-VD groups were significantly increased (p < 0.001). However, there are no significant difference between VE-VD, IE-VD and TE-VD groups (p> 0.05). In addition, hippocampal dopamine and 5-HT level significantly decreased in VD group when compared with C group (p < 0.001); hippocampal dopamine and 5-HT level in VE-VD, IE-VD and TE-VD groups were significantly increased when compared with VD group (p < 0.05). However, there are no significant difference between VE-VD, IE-VD and TE-VD groups (p> 0.05). Therefore, we concluded that different physical exercises, included treadmill exercise, in-voluntary exercise and voluntary exercise, all can protect cognition by up-regulate dopamine and 5-HT level in rats of vascular dementia.
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Affiliation(s)
- Linlin Zhang
- Provincial University Key Laboratory of Sport and Health Science, School of Physical Education and Sport Sciences, Fujian Normal University, Fuzhou, 350007, China; Capital University of Physical Education and Sports, Beijing, 100191, China
| | - Yongzhao Fan
- Capital University of Physical Education and Sports, Beijing, 100191, China; Comprehensive Key Laboratory of Sports Ability Evaluation and Research of the General Administration of Sport of China, Beijing Key Laboratory of Sports Function Assessment and Technical Analysis, Capital University of Physical Education and Sports, Beijing, 100191, China
| | - Xiaoyang Kong
- Li-Ning Sports Science Research Center, Beijing, China
| | - Wu Hao
- Capital University of Physical Education and Sports, Beijing, 100191, China; Comprehensive Key Laboratory of Sports Ability Evaluation and Research of the General Administration of Sport of China, Beijing Key Laboratory of Sports Function Assessment and Technical Analysis, Capital University of Physical Education and Sports, Beijing, 100191, China.
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7
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Orr ME, Reveles KR, Yeh CK, Young EH, Han X. Can oral health and oral-derived biospecimens predict progression of dementia? Oral Dis 2020; 26:249-258. [PMID: 31541581 PMCID: PMC7031023 DOI: 10.1111/odi.13201] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/09/2019] [Accepted: 08/30/2019] [Indexed: 12/13/2022]
Abstract
Growing evidence indicates that oral health and brain health are interconnected. Declining cognition and dementia coincide with lack of self‐preservation, including oral hygiene. The oral microbiota plays an important role in maintaining oral health. Emerging evidence suggests a link between oral dysbiosis and cognitive decline in patients with Alzheimer's disease. This review showcases the recent advances connecting oral health and cognitive function during aging and the potential utility of oral‐derived biospecimens to inform on brain health. Collectively, experimental findings indicate that the connection between oral health and cognition cannot be underestimated; moreover, oral biospecimens are abundant and readily obtainable without invasive procedures, which may help inform on cognitive health.
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Affiliation(s)
- Miranda E Orr
- Barshop Institute for Longevity and Aging Studies, UT Health San Antonio, San Antonio, Texas.,Geriatric Research, Education & Clinical Center and Research Service, South Texas Veterans Health Care System, San Antonio, Texas.,Department of Medicine, UT Health San Antonio, San Antonio, Texas.,Biggs Institute for Alzheimer's and Neurodegenerative Diseases, UT Health San Antonio, San Antonio, Texas.,Gerontology and Geriatric Medicine, Sticht Center for Healthy Aging and Alzheimer's Prevention, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Kelly R Reveles
- College of Pharmacy, The University of Texas at Austin, Austin, Texas.,Pharmacotherapy Education & Research Center, UT Health San Antonio, San Antonio, Texas
| | - Chih-Ko Yeh
- Barshop Institute for Longevity and Aging Studies, UT Health San Antonio, San Antonio, Texas.,Geriatric Research, Education & Clinical Center and Research Service, South Texas Veterans Health Care System, San Antonio, Texas.,Comprehensive Dentistry, School of Dentistry, UT Health San Antonio, San Antonio, Texas
| | - Eric H Young
- College of Pharmacy, The University of Texas at Austin, Austin, Texas.,Pharmacotherapy Education & Research Center, UT Health San Antonio, San Antonio, Texas
| | - Xianlin Han
- Barshop Institute for Longevity and Aging Studies, UT Health San Antonio, San Antonio, Texas.,Department of Medicine, UT Health San Antonio, San Antonio, Texas
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8
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Kanno N, Fujiwara K, Yoshida S, Kato T, Kato Y. Dynamic Changes in the Localization of Neuronatin-Positive Cells during Neurogenesis in the Embryonic Rat Brain. Cells Tissues Organs 2019; 207:127-137. [DOI: 10.1159/000504359] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Accepted: 10/24/2019] [Indexed: 11/19/2022] Open
Abstract
Neuronatin (NNAT) was first identified as a gene selectively and abundantly expressed in the cytoplasm of the newborn mouse brain, and involved in neonatal neurogenesis. However, the particular roles of NNAT in the developing prenatal brain have not been identified, especially in mid to late stages. In this study, we performed immunohistochemical analyses of NNAT and SOX2 proteins, a nuclear transcription factor and neural stem/progenitor marker, in the rat brain on embryonic days 13.5, E16.5, and E20.5. NNAT signals were broadly observed across the developing brain on E13.5 and gradually more localized in later stages, eventually concentrated in the alar and basal parts of the terminal hypothalamus, the alar plate of prosomere 2 of the thalamus, and the choroid plexus in the lateral and fourth ventricles on E20.5. In particular, the mammillary body in the basal part of the terminal hypothalamus, a region with a high number of SOX2-positive cells, evidenced intense NNAT signals on E20.5. The intracellular localization of NNAT showed diverse profiles, suggesting that NNAT was involved in various cellular functions, such as cell differentiation and functional maintenance, during prenatal neurogenesis in the rat brain. Thus, the present observations suggested diverse and active roles of the NNAT protein in neurogenesis. Determining the function of this molecule may assist in the elucidation of the mechanisms involved in brain development.
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Kurozumi A, Hara T, Sakamoto S, Araki D, Iida-Tamada S, Kuroda-Ishimine C, Minagi S. Effects of the loss and reconstruction of molar occlusal support on memory retrieval and hippocampal neuron density in rats. J Prosthodont Res 2019; 63:283-287. [PMID: 30686619 DOI: 10.1016/j.jpor.2018.12.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 12/07/2018] [Accepted: 12/19/2018] [Indexed: 11/17/2022]
Abstract
PURPOSE Animal experiments have shown that the loss of occlusal support causes impairments in spatial cognition. Many reports have focused on the memory encoding process, and only few studies have investigated the effect on memory retrieval. This study aimed to examine the effects of both the loss and reconstruction of occlusal support on the memory retrieval process and on the number of hippocampal pyramidal cells. METHODS The experimental animals were divided into a molarless group, in which molars were extracted, a denture-wearing molarless group with experimental dentures inserted after molar extraction, and a control group. Radial maze trials were performed for 20 consecutive days (acquisition phase). The rats were tested on long-term memory retention following the acquisition phase in eight trials every five days, and in an additional trial 20 days later (probe phase). RESULTS The denture-wearing molarless group showed higher levels of spatial learning and memory than the molarless group. There were no significant differences in memory retrieval during the probe phase between the denture-wearing molarless and the control group. The molarless group showed significantly worse spatial learning and memory and had fewer neurons in the hippocampus than the control group. CONCLUSIONS Our results suggest that the loss of occlusal support decreases the number of pyramidal cells in the hippocampus and impairs memory decoding and retrieval. However, this effect is suppressed by the reconstruction of occlusal support.
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Affiliation(s)
- Akimasa Kurozumi
- Occlusion and Removable Prosthodontics, Okayama University Hospital, Okayama, Japan
| | - Tetsuya Hara
- Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
| | - Shunichi Sakamoto
- Occlusion and Removable Prosthodontics, Okayama University Hospital, Okayama, Japan
| | - Daisuke Araki
- Occlusion and Removable Prosthodontics, Okayama University Hospital, Okayama, Japan
| | - Sachiyo Iida-Tamada
- Occlusion and Removable Prosthodontics, Okayama University Hospital, Okayama, Japan
| | | | - Shogo Minagi
- Department of Occlusal and Oral Functional Rehabilitation, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
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10
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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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11
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Effect of Voluntary Wheel Running on Striatal Dopamine Level and Neurocognitive Behaviors after Molar Loss in Rats. Behav Neurol 2017; 2017:6137071. [PMID: 29358845 PMCID: PMC5735578 DOI: 10.1155/2017/6137071] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/25/2017] [Accepted: 10/02/2017] [Indexed: 12/12/2022] Open
Abstract
The aim of the present study is to evaluate the effect of voluntary wheel running on striatal dopamine level and behavior of cognition and emotion in molar loss rats. Twenty-four Sprague-Dawley rats were enrolled in this study and randomly divided into following 4 groups: control group (C group), molar loss group (ML group), 1-week physical exercise before molar loss group (1W-ML group), and 4-week physical exercise before molar loss group (4W-ML group). The rats both in 4W-ML and 1W-ML groups were placed in the voluntary running wheel in order to exercise for 4 weeks and 1 week, respectively. Then, the rats in 4W-ML, 1W-M, and ML groups received bilateral molar loss operation. After 10 days, striatal dopamine level was detected by in vivo microdialysis coupled with high-performance liquid chromatography (HPLC) and electrochemical detection. All the rats received behavior test after microdialysis detection. The behavior tests including passive avoidance test were used to assess cognition and elevated plus maze test for emotion. The results indicated that voluntary wheel running promoted striatal dopamine level in rats of molar loss. Behavioral data indicated that voluntary wheel running promoted cognition and emotion recovery after molar loss. Therefore, we concluded physical exercise significantly improved the neurocognitive behaviors and increased the striatal dopamine level after molar loss in rats.
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12
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Hara T, Kawanishi K, Ohno A, Iida S. The evolution of research on occlusion and brain function. J Prosthodont Res 2016; 61:6-8. [PMID: 27354029 DOI: 10.1016/j.jpor.2016.06.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 05/11/2016] [Accepted: 06/02/2016] [Indexed: 10/21/2022]
Affiliation(s)
- Tetsuya Hara
- Department of Occlusal and Oral Functional Rehabilitation, Okayama University Graduate School, Japan.
| | - Katsuya Kawanishi
- Department of Oral Rehabilitation, Division of Occlusion and Removable Prosthodontics, Health Sciences University of Hokkaido School of Dentistry, Japan
| | - Akinori Ohno
- Division of Prosthodontics & Oral Rehabilitation, Department of Oral Function and Restoration, Graduate School of Dentistry, Kanagawa Dental University, Japan
| | - Sachiyo Iida
- Department of Occlusion and Removable Prosthodontics, Okayama University Hospital, Japan
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13
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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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