The effect of the loss of molar teeth on spatial memory and acetylcholine release from the parietal cortex in aged rats

Kato, Takeshi; Usami, Takeshi; Noda, Yukihiro; Hasegawa, Masaya; Ueda, Minoru; Nabeshima, Toshitaka

doi:10.1016/s0166-4328(97)86078-0

Cited by 133 publications

(143 citation statements)

References 7 publications

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“…Chewing causes regional increases in cerebral blood flow and neuronal activity in the human brain (7,8). By contrast, it has been shown that reduced mastication and occlusal disharmony impair spatial memory and promote the degeneration of hippocampal neurons (9,10). We, as well as others, have also previously demonstrated that reducing mastication by feeding mice a soft diet inhibits the survival of newly generated neurons in the DG (11,12).…”

Section: Introductionmentioning

confidence: 86%

Forced mastication increases survival of adult neural stem cells in the hippocampal dentate gyrus

Akazawa

Kitamura

Fujihara

et al. 2012

International Journal of Molecular Medicine

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Abstract. In this study, we examined the effect of forced mastication on neurogenesis in the hippocampal dentate gyrus (DG) of adult mice. Six-week-old mice were subjected to either a hard or normal diet for 13 weeks. They received a daily injection of bromodeoxyuridine (BrdU) for 12 consecutive days beginning at 14 weeks of age. The number of BrdU-positive cells in the DG was counted 1 day after and 5 weeks after the final BrdU injection. The number of BrdU-positive cells 1 day after injection did not differ between the 2 diet groups. However, the number of BrdU-positive cells in the group fed the hard diet was significantly increased 5 weeks after BrdU injection compared to the group fed the normal diet. The results of the Morris water maze test showed that mice fed a hard diet required significantly less time to reach the platform than the control mice when tested at 10 days. Moreover, mice in the group fed the hard diet spent significantly more time in the former platform area than the group fed the normal diet, indicating that hard diet feeding improved spatial memory compared to normal diet feeding. Real-time PCR analysis showed that the expression of glutamate receptor 1 mRNA was significantly increased in the group fed the hard diet compared with the group fed the normal diet. These results suggest that mastication increases the survival of adult neural stem cells in the hippocampal DG.

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Section: Introductionmentioning

confidence: 86%

Forced mastication increases survival of adult neural stem cells in the hippocampal dentate gyrus

Akazawa

Kitamura

Fujihara

et al. 2012

International Journal of Molecular Medicine

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“…Visual disorders due to aging are not likely the cause of this change. Nabeshima et al 4) reported no differences in the selection rate of dark places between juvenile and senile groups and Kato et al 11) reported that 8 to 13-month old pre-senile hamsters could adjust to various light and dark period cycles. Rosenberg 12) reported that senile hamsters showed phase displacement of activity induced by optical pulses, similar to juvenile hamsters, with few a ging-related changes in sensitivity to light.…”

Section: Discussionmentioning

confidence: 99%

Relationship between light and dark period activity cycles and oral condition in senescence-accelerated mice

Iinuma

Yasui

Oonishi

et al. 2011

Okajimas Folia Anat. Jpn.

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IntroductionThe aging of the Japanese society is associated with an increase in the number of patients with senile dementia, and provisions to deal with this problem are becoming increasingly important. There is a clear relationship between the oral condition and general health 1,2) , but the relationship between oral conditions with aging and dementia r emains unclear 3) . In the present study, we used s enescenceaccelerated mice (SAMP1) to evaluate the effects of tooth absence and masticatory abnormalities induced during the juvenile period on life cycle and activity at later ages during which peripheral symptoms of dementia appear. Rodents, however, are nocturnal animals with higher activity levels in the dark period than in the light period, showing an activity cycle that follows the biological clock, and diurnal activity levels in senile rats aged 90 to 108 weeks is significantly shorter than that in juvenile rats, with no differences in the activity levels between the light and dark periods. Further, spontaneous activity is decreased, indicating that the nocturnal behavior of senescent animals is disturbed 4) . In the present study, this characteristic was used as an index of dementia. Materials and MethodsFifty male SAMP1 mice were used. The strain was kindly donated by the Institute of Frontier Medical Sciences, Kyoto University. We bred brother-sister in the animal facility of the Central Research Division at the School of Dentistry, Asahi University. The SAMP8 mouse has an average life span of 12 months (about half life span of normal mice) and begins to show deficits in learning and memory and aging at 5 months. The characteristics of this strain were described in detail by Takeda et al. 5,6) . The a nimals were bred and maintained under conventional conditions; housed in groups of 5 in plastic cages (175 W × 245 D × 125 H mm) under temperature (23 ± 1°C), humidity (55 ± 2%), and light (12 h; light period, 6:00 -18:00; dark period, 18:00 -6:00) controlled conditions; and water was available ad libitum. This experiment was conducted Okajimas Folia Anat. Jpn., 88(1): 29-36, May, 2011 Relationship between light and dark period activity cycles and oral condition in senescence-accelerated mice Summary: We investigated the effect of tooth absence and masticatory abnormalities due to powdered food feeding starting during the juvenile period on light and dark period activity cycles in senescence-accelerated mice (SAMP1) . SAMP1 were divided into 5 groups: Group 1, maxillo-mandibular molar tooth extraction; Group 2, maxillary molar tooth extraction; Group 3, mandibular molar tooth extraction; Group 4, powdered food; and Group 5, sham-operated control. Senescence was observed earliest in the powdered food group. Total 24-hour activity was higher in the control group than in the four other groups. In the powdered food group, the dark period activity decreased to less than 60% of the total activity in the 36th week. In the tooth extraction groups (Groups 1-3), dark period activity decreased to less than 60% of...

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“…In this method, although animals can move freely, the tube connecting the dialyzer and dialysis membrane restricts movements. Therefore, in past studies, drug administration 7 or electrical stimulation 8 was required to activate the hippocampus. However, the use of a telemetric biosensor in the present study provided the rats with complete freedom of movement.…”

Section: Experiments Methodsmentioning

confidence: 99%

“…Furthermore, one study reported that fewer pyramidal cells were present in the hippocampal CA1 region in rats with missing molars. 5 Furthermore, Kato et al 7 used microdialysis methods and reported that molar tooth loss in rats decreased the release of acetylcholine in the parietal cortex, and Okuda et al 8 used the same technique and documented that glutamate release in the hippocampus was reduced. These studies suggest that molar tooth loss may impair learning and memory.…”

Section: Introductionmentioning

confidence: 99%

Hippocampal Glutamate Release on Learning and Memory in Teeth-loss Rats

Matsuno

Inoue

2008

Prosthodont Res. Pract.

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The present study investigated the effects of tooth loss on learning and memory in rats by measuring hippocampal glutamate levels during a passive-avoidance task. The results clarified that tooth loss may be one of the factors inpending learning and memory; this is significant in the field of prosthodontics. AbstractPurpose: To clarify the effects of molar tooth loss on learning and memory, hippocampal glutamate release during a passive-avoidance task was measured with a telemetric glutamate biosensor. Methods: Male Sprague-Dawley rats were used. Under general anesthesia, all the maxillary molars were extracted from the EXT group rats (n = 8); those in the CON group (control, n = 8) were anesthetized without tooth extraction. At age 7 weeks, the rats were subjected to a passive-avoidance task consisting of acquisition and retention trials. Simultaneously, hippocampal glutamate release was measured. First, during the acquisition trial, the rats were placed in a light compartment, and the duration before they entered a dark compartment was measured (reaction latency). Immediately after the rat entered the dark compartment, an electric shock was applied through a grid floor. After 24 h, the retention trial was performed, and the reaction latency was measured in the same manner. Further, a biosensor was used to measure the release of hippocampal glutamate before and after the start of each trial. Results: Regarding the reaction latency during the passive-avoidance task, no significant differences were seen between the groups in the acquisition trial. Reaction latency increased in both groups in the retention trial, but was significantly shorter in the EXT group. Furthermore, hippocampal glutamate release in the acquisition trial was significantly shorter in the EXT group, but in the retention trial, no significant difference in glutamate release was seen between the groups. Conclusion: Molar tooth loss may impede learning and memory.

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The effect of the loss of molar teeth on spatial memory and acetylcholine release from the parietal cortex in aged rats

Cited by 133 publications

References 7 publications

Forced mastication increases survival of adult neural stem cells in the hippocampal dentate gyrus

Forced mastication increases survival of adult neural stem cells in the hippocampal dentate gyrus

Relationship between light and dark period activity cycles and oral condition in senescence-accelerated mice

Hippocampal Glutamate Release on Learning and Memory in Teeth-loss Rats

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