Molarless-induced changes of spines in hippocampal region of SAMP8 mice

Department of Oral Anatomy, Division of Oral Structure, Function and Development, Asahi University School of Dentistry, 1851 Hozumi, Mizuho, Gifu 501-0296, Japan.
Brain Research (Impact Factor: 2.83). 10/2005; 1057(1-2):191-5. DOI: 10.1016/j.brainres.2005.07.038
Source: PubMed

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.

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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 [15]. Briefly, at least 20 Golgi-impregnated cells were randomly chosen from each animal for quantitative analysis of dendritic spines. "
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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
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