Occlusal disharmony transiently decrease cognition via cognitive suppressor molecules and partially restores cognitive ability via clearance molecules

Maeshiba, Munehisa; Kajiya, Hiroshi; Tsutsumi, Takashi; Migita, Keisuke; Goto-T, Kazuko; Kono, Yuri; Tsuzuki, Takashi; Ohno, Jun

doi:10.1016/j.bbrc.2022.01.048

Cited by 3 publications

(5 citation statements)

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“…One of key areas of the brain involved in this processing is the hippocampus ( Furini et al, 2020 ). In a previous study, occlusal disharmony impaired cognitive ability of young mice when performing the NOR task 1 and 4 weeks after the loading ( Maeshiba et al, 2022 ). Moreover, the protein levels of various cognitive suppressor molecules in the hippocampus, such as amyloid-β and phosphorylated tau, were increased at 1 week and were reduced at 4 weeks after the loading ( Maeshiba et al, 2022 ).…”

Section: Discussionmentioning

confidence: 95%

“…In a previous study, occlusal disharmony impaired cognitive ability of young mice when performing the NOR task 1 and 4 weeks after the loading ( Maeshiba et al, 2022 ). Moreover, the protein levels of various cognitive suppressor molecules in the hippocampus, such as amyloid-β and phosphorylated tau, were increased at 1 week and were reduced at 4 weeks after the loading ( Maeshiba et al, 2022 ). Anorexigenic peptide signals in the hypothalamus have been reportedly associated with anorexia-induced recognition decline in juvenile mice ( Rokot et al, 2021 ).…”

Section: Discussionmentioning

confidence: 95%

“…Thus, cerebral orexigenic peptides may alter cognitive functions in adolescents. Occlusal disharmony impairs cognitive function by upregulating hippocampal cognitive inhibitors in adult mice ( Maeshiba et al, 2022 ). However, to the best of our knowledge, no prior study has investigated the relationship between orexigenic peptides associated with cognitive function and occlusal disharmony in adolescent mice.…”

Section: Introductionmentioning

confidence: 99%

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Malocclusion impairs cognitive behavior via AgRP signaling in adolescent mice

et al. 2023

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IntroductionOcclusal disharmony induced by deteriorating oral health conditions, such as tooth loss and decreased masticatory muscle due to sarcopenia, is one of the causes of cognitive impairment. Chewing is an essential oral function for maintaining cognitive function not only in the elderly but also in young people. Malocclusion is an occlusal disharmony that commonly occurs in children. The connection between a decline in cognitive function and malocclusion in children has been shown with chronic mouth breathing, obstructive sleep apnea syndrome, and thumb/digit sucking habits. However, the mechanism of malocclusion-induced cognitive decline is not fully understood. We recently reported an association between feeding-related neuropeptides and cognitive decline in adolescent mice with activity-based anorexia. The aim of the present study was to assess the effects of malocclusion on cognitive behavior and clarify the connection between cognitive decline and hypothalamic feeding-related neuropeptides in adolescent mice with malocclusion.MethodsFour-week-old mice were randomly assigned to the sham-operated solid diet-fed (Sham/solid), sham-operated powder diet-fed (Sham/powder), or malocclusion-operated powder diet-fed (Malocclusion/powder) group. We applied composite resin to the mandibular anterior teeth to simulate malocclusion. We evaluated cognitive behavior using a novel object recognition (NOR) test, measured hypothalamic feeding-related neuropeptide mRNA expression levels, and enumerated c-Fos-positive cells in the hypothalamus 1 month after surgery. We also evaluated the effects of central antibody administration on cognitive behavior impairment in the NOR test.ResultsThe NOR indices were lower and the agouti-related peptide (AgRP) mRNA levels and number of c-Fos-positive cells were higher in the malocclusion/powder group than in the other groups. The c-Fos-positive cells were also AgRP-positive. We observed that the central administration of anti-AgRP antibody significantly increased the NOR indices.DiscussionThe present study suggests that elevated cerebral AgRP signaling contributes to malocclusion-induced cognitive decline in adolescents, and the suppression of AgRP signaling can be a new therapeutic target against cognitive decline in occlusal disharmony.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Malocclusion impairs cognitive behavior via AgRP signaling in adolescent mice

et al. 2023

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“…Furthermore, the experimental unilateral anterior crossbite in experimental animals revealed a negative impact on the motor nuclei in the brain stem via the trigeminal mesencephalic nucleus [ 24 ]. Occlusal disharmony induced the accumulation of molecules such as amyloid-β and phosphorylated tau, which resulted in protection against transient dementia in young but not older individuals [ 25 ]. Taken together, these findings show that malocclusion influences brain function and BBF.…”

Section: Introductionmentioning

confidence: 99%

Skeletal Anterior Open Bite Attenuates the Chewing-Related Increase in Brain Blood Flow

Kariya,

Kanzaki,

Kumazawa

et al. 2024

Dentistry Journal

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The masticatory function of patients with skeletal anterior open bite (OPEN) is reported to be impaired compared with that of patients with normal occlusion (NORM). In this study, we compared brain blood flow (BBF) in patients with OPEN and NORM and investigated the factors related to BBF during mastication in patients with OPEN. The study included 17 individuals with NORM and 33 patients with OPEN. The following data were collected: number of occlusal contacts, jaw movement variables during mastication, and BBF measured with functional near-infrared spectroscopy during chewing. The number of occlusal contacts, maximum closing and opening speeds, closing angle, and vertical amplitude were smaller in the OPEN than in the NORM group. Interestingly, BBF increased less in the OPEN group. Correlation analysis revealed that several parameters, including number of occlusal contacts and closing angle, were correlated with changes in BBF during mastication. These results suggest that not only occlusion but also jaw movement variables and factors related to masticatory muscles contribute to the chewing-related increase in BBF. In conclusion, BBF increases less during mastication in patients with OPEN than in those with NORM. In addition, the higher increase in BBF is correlated with jaw movement. Together, we discovered that OPEN exhibits significant adverse effects not only on masticatory function but also on brain function.

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“…In rat models of occlusal disharmony, amyloid-β is increased in the hippocampus and this was also associated with cognitive dysfunction [ 32 , 33 ]. Studies in similar mouse models of occlusal disharmony report significant increases in the expression of interleukin-1β in the brain, which was later accompanied by the appearance of amyloid-β and hyperphosphorylated tau in the hippocampus, and the induction of learning and memory deficits [ 34 ].…”

Section: Introductionmentioning

confidence: 99%

The Sedentary Lifestyle and Masticatory Dysfunction: Time to Review the Contribution to Age-Associated Cognitive Decline and Astrocyte Morphotypes in the Dentate Gyrus

Mendes

Almeida

Falsoni

et al. 2022

IJMS

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As aging and cognitive decline progresses, the impact of a sedentary lifestyle on the appearance of environment-dependent cellular morphologies in the brain becomes more apparent. Sedentary living is also associated with poor oral health, which is known to correlate with the rate of cognitive decline. Here, we will review the evidence for the interplay between mastication and environmental enrichment and assess the impact of each on the structure of the brain. In previous studies, we explored the relationship between behavior and the morphological features of dentate gyrus glial fibrillary acidic protein (GFAP)-positive astrocytes during aging in contrasting environments and in the context of induced masticatory dysfunction. Hierarchical cluster and discriminant analysis of GFAP-positive astrocytes from the dentate gyrus molecular layer revealed that the proportion of AST1 (astrocyte arbors with greater complexity phenotype) and AST2 (lower complexity) are differentially affected by environment, aging and masticatory dysfunction, but the relationship is not straightforward. Here we re-evaluated our previous reconstructions by comparing dorsal and ventral astrocyte morphologies in the dentate gyrus, and we found that morphological complexity was the variable that contributed most to cluster formation across the experimental groups. In general, reducing masticatory activity increases astrocyte morphological complexity, and the effect is most marked in the ventral dentate gyrus, whereas the effect of environment was more marked in the dorsal dentate gyrus. All morphotypes retained their basic structural organization in intact tissue, suggesting that they are subtypes with a non-proliferative astrocyte profile. In summary, the increased complexity of astrocytes in situations where neuronal loss and behavioral deficits are present is counterintuitive, but highlights the need to better understand the role of the astrocyte in these conditions.

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Occlusal disharmony transiently decrease cognition via cognitive suppressor molecules and partially restores cognitive ability via clearance molecules

Cited by 3 publications

References 32 publications

Malocclusion impairs cognitive behavior via AgRP signaling in adolescent mice

Malocclusion impairs cognitive behavior via AgRP signaling in adolescent mice

Skeletal Anterior Open Bite Attenuates the Chewing-Related Increase in Brain Blood Flow

The Sedentary Lifestyle and Masticatory Dysfunction: Time to Review the Contribution to Age-Associated Cognitive Decline and Astrocyte Morphotypes in the Dentate Gyrus

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