Effects of chronic stress of early tooth extraction on hippocampus in senescence-accelerated mice

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This evaluations were whether long-term tooth loss induces functional and morphologic changes in the hippocampus in senescence-accelerated mice(SAMP8). The teeth were extracted at an early age.The results were as follow.1, Plasma corticosterone concentration as a stressor was significantly higher in old or mature mice with long-term tooth loss groups than in the age-matched controls.2, In the Morris water maze learning and spatial memory trials was significantly slower in the mature or old long-term tooth loss groups compared with the age-matched controls.3, The number of hippocampal neurons was significantly reduced in the CA3 region of the hippocampus in the mature and old long-term tooth loss groups compared with their age-matched controls, but there was no significant difference in the CA1 or dentate gyrus(DG) region between the mature or old long-term tooth loss groups and their age-matched controls.4, The number of GFAP-positive cells was significantly higher in the CA3 region of the hippocampus in the mature or old long-term tooth loss groups compared with age-matched controls. However, no significant difference was observed in the CA1 or DG of the hippocampus in the mature or old mice.5, The number of BrdU-positive cells was significantly increased in the DG of the hippocampus in the mature or old long-term tooth loss groups compared with age-matched controls.6, In the hippocampus, note the significant decrease in synaptopysin expression in the mature or old long-term tooth loss groups compared with age-matched controls.The findings indicated that long-term tooth loss enhances the effects of aging on the hippocampus in mice.