Molarless condition suppresses proliferation but not differentiation rates into neurons in the rat dentate gyrus

Aoki, Hiromichi; Kimoto, Katsuhiko; Hori, Norio; Hoshi, Noriyuki; Yamamoto, Toshiharu; Onozuka, Minoru

doi:10.1016/j.neulet.2009.11.041

Cited by 16 publications

(16 citation statements)

References 30 publications

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“…For instance, mean plasma levels of corticosterone in rats with incisal caps are significantly higher than those in rats without incisal caps (Yoshihara et al 2001). Rats in the molarless group exhibited a significantly higher level of corticosterone than those in the control group at 24 weeks of age (Aoki et al 2010). These observations are consistent with the present results that the increased mRNA levels of Gr, App, and Bace1 in the rat hippocampus were induced by occlusal disharmony and plasma levels of corticosterone increased in a timedependent manner.…”

Section: Discussionmentioning

confidence: 90%

“…This was 1.7 times compared with that in the C group at 8 weeks. In the other rat chronic stress models, the values were increased 3.5 times by isolation stress (Dong et al 2008), three times by immobilization stress (Radecki et al 2005), 1.9 times by cusp-less stress , and 1.3 times by molarless stress (Aoki et al 2010) compared with each control group. These findings suggest that the stress level in our study was milder than that in other stress models.…”

Section: Discussionmentioning

confidence: 91%

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Occlusal Disharmony Increases Amyloid-β in the Rat Hippocampus

et al. 2011

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Amyloid-β plays a causative role in Alzheimer's disease. Occlusal disharmony causes chronic psychological stress, and psychological stress increases amyloid-β accumulation. The purpose of the present study was to investigate whether occlusal disharmony-induced psychological stress affects the accumulation of amyloid-β and its related gene expressions in the rat hippocampus. Eight-week-old male Wistar rats (n = 18) were divided into three groups of six rats each: (1) a control group that received no treatment for 8 weeks; (2) an occlusal disharmony group that underwent cutoff maxillary molar cusps for 8 weeks; and (3) a recovered group that underwent cutoff maxillary molar cusps for 4 weeks followed by recovery for 4 weeks. Occlusal disharmony increased plasma corticosterone levels in a time-dependent manner. Levels of amyloid-β 40 and 42, glucocorticoid receptor (Gr) protein, and cleaved caspase 3 (Casp3) as well as gene expressions of amyloid precursor protein, beta-secretase, Casp3, and Gr in the hippocampus in the occlusal disharmony group were significantly higher than those in the control group (P < 0.016). These findings were significantly improved by recovery of occlusion (P < 0.016). These results indicate that psychological stress induced by occlusal disharmony reversibly induces amyloid-β 40 and 42 in the rat hippocampus through the glucocorticoid signal.

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Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 91%

Occlusal Disharmony Increases Amyloid-β in the Rat Hippocampus

et al. 2011

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“…These approaches revealed that masticatory dysfunction reduces spatial learning and memory in water maze tests in rats [8,11] and mice [11-13], and that these deficits seem to increase with aging and time after tooth loss [8]. Induced molarless subjects, revealed reduced neurogenesis in young rats [14], and there is a loss of astrocytes, neurons and dendritic spines in the hippocampus of aged rats and mice [7,14,15]. Young mice fed a soft diet show reduced neurogenesis and BDNF levels [16,17], whereas progressive synaptic reduction and pyramidal neuron losses are observed in aged mice [6,18].…”

Section: Introductionmentioning

confidence: 99%

Spatial memory decline after masticatory deprivation and aging is associated with altered laminar distribution of CA1 astrocytes

et al. 2012

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BackgroundChewing imbalances are associated with neurodegeneration and are risk factors for senile dementia in humans and memory deficits in experimental animals. We investigated the impact of long-term reduced mastication on spatial memory in young, mature and aged female albino Swiss mice by stereological analysis of the laminar distribution of CA1 astrocytes. A soft diet (SD) was used to reduce mastication in the experimental group, whereas the control group was fed a hard diet (HD). Assays were performed in 3-, 6- and 18-month-old SD and HD mice.ResultsEating a SD variably affected the number of astrocytes in the CA1 hippocampal field, and SD mice performed worse on water maze memory tests than HD mice. Three-month-old mice in both groups could remember/find a hidden platform in the water maze. However, 6-month-old SD mice, but not HD mice, exhibited significant spatial memory dysfunction. Both SD and HD 18-month-old mice showed spatial memory decline. Older SD mice had astrocyte hyperplasia in the strata pyramidale and oriens compared to 6-month-old mice. Aging induced astrocyte hypoplasia at 18 months in the lacunosum-moleculare layer of HD mice.ConclusionsTaken together, these results suggest that the impaired spatial learning and memory induced by masticatory deprivation and aging may be associated with altered astrocyte laminar distribution and number in the CA1 hippocampal field. The underlying molecular mechanisms are unknown and merit further investigation.

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“…Although there are many studies on hippocampal neurogenesis under various conditions (Mu et al 2007;Aoki et al 2010), fewer studies have been conducted on comparative study on neuronal development in other areas of the brain (Lephart and Watson 1999), such as in the developing cerebellar cortex (Takács et al 2007(Takács et al , 2008. In this study, therefore, we investigated and compared chronological changes of DCX-immunoreactive developing/ maturing neurons in the somatosensory cortex (SSC) and hippocampal CA1 region at various early postnatal stages.…”

Section: Introductionmentioning

confidence: 99%

Time Course of Postnatal Distribution of Doublecortin Immunoreactive Developing/Maturing Neurons in the Somatosensory Cortex and Hippocampal CA1 Region of C57BL/6 Mice

Yoo

Choi

et al. 2011

Cell Mol Neurobiol

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In this study, we observed neuroblast differentiation in the somatosensory cortex (SSC) and hippocampal CA1 region (CA1), which is vulnerable to oxidative stress, of the mouse at various early postnatal days (P) 1, 7, 14, and 21 using doublecortin (DCX, a marker for neuroblasts). Cresyl violet and NeuN (Neuronal Nuclei) staining showed development of layers as well as neurons in the SSC and CA1. At P1, DCX-positive neuroblasts expressed strong DCX immunoreactivity in both the SSC and CA1. Thereafter, DCX immunoreactivity was decreased with time. At P7, many DCX-immunoreactive neuroblasts were well detected in the SSC and CA1. At P14, some DCX-positive neuroblasts were found in the SSC and CA1: The immunoreactivity was weak. At P21, DCX immunoreactivity was hardly found in cells in the SSC and CA1. These results suggest that DCX-positive neuroblasts were significantly decreased in the mouse SSC and CA1 from P14.

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Molarless condition suppresses proliferation but not differentiation rates into neurons in the rat dentate gyrus

Cited by 16 publications

References 30 publications

Occlusal Disharmony Increases Amyloid-β in the Rat Hippocampus

Occlusal Disharmony Increases Amyloid-β in the Rat Hippocampus

Spatial memory decline after masticatory deprivation and aging is associated with altered laminar distribution of CA1 astrocytes

Time Course of Postnatal Distribution of Doublecortin Immunoreactive Developing/Maturing Neurons in the Somatosensory Cortex and Hippocampal CA1 Region of C57BL/6 Mice

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