Molarless-induced changes of spines in hippocampal region of SAMP8 mice
ABSTRACT We examined the effect of the molarless condition on the dendritic spines of hippocampal pyramidal cells in SAMP8 mice in comparison to its effect on learning ability in a maze test. The molarless condition caused a decrease in the number of the spines of CA1 pyramidal cells only in the aged mice showing a reduced learning ability. The results suggest the involvement of the molarless condition in an attenuation of input activities in the hippocampal synapses.
- SourceAvailable from: Toshiharu Yamamoto
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- "Consistent with these reports, in the present study there were no apparent changes in the morphology or number of apical dendritic spines between the bite-raised and control groups. Thus, we analyzed dendritic spine number as described previously . Briefly, at least 20 Golgi-impregnated cells were randomly chosen from each animal for quantitative analysis of dendritic spines. "
ABSTRACT: The present study examined the effect of the bite-raised condition on the number of dendritic spines on hippocampal pyramidal cells in SAMP8 mice and related the results with learning ability in a water maze test. Aged mice in the bite-raised condition had reduced learning ability and a lower number of CA1 pyramidal cell dendritic spines. The results suggest that the bite-raised condition exacerbates the age-related spatial learning impairment, and that this may be due to the degeneration of hippocampal dendritic spines.Neuroscience Letters 09/2008; 441(2):141-4. DOI:10.1016/j.neulet.2008.05.027
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ABSTRACT: We examined the effect of occlusal disharmony in senescence-accelerated (SAMP8) mice on plasma corticosterone levels, hippocampal neuron number, and spatial performance in the water maze. The bite-raised condition was associated with an accelerated age-related decline in spatial memory, increased plasma corticosterone levels, and a decreased number of neurons in the hippocampal CA3 region. The findings suggest that the bite-raised condition in aged SAMP8 mice induces hippocampal neuron loss, thereby leading to senile memory deficits.Neuroscience Letters 04/2007; 414(2):188-91. DOI:10.1016/j.neulet.2006.12.020
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ABSTRACT: To evaluate the mechanism underlying impaired cognitive function due to occlusal disharmony, we examined the effect of the bite-raised condition on spatial performance and hippocampal expression of glucocorticoid receptors (GR) and glucocorticoid receptor messenger ribonucleic acid (GRmRNA) using behavioral, immunohistochemical, and in situ hybridization techniques. Learning ability in the water maze test was significantly impaired in aged bite-raised mice compared with age-matched control mice. There was no difference between control and bite-raised young and middle-aged mice. Also, immunohistochemical and in situ hybridization analysis showed that the bite-raised condition enhanced the age-related decrease in GR and GRmRNA expression in the hippocampus. In particular, GR and GRmRNA expressions were significantly decreased in aged bite-raised mice compared to age-matched control mice. These findings suggest that the bite-raised condition in aged SAMP8 mice decreases GR and GRmRNA, which impairs the hypothalamic-pituitary-adrenal feedback inhibition, thereby leading to memory deficits.Neuroscience Letters 12/2007; 427(2):71-6. DOI:10.1016/j.neulet.2007.09.020