Abstract
Objective: DNA microarray analysis was performed to investigate changes in gene expression in thehippocampus caused by physiological aging and the loss of molarteeth.
Methods: Wild-type C57BL/6J Jcl mice which show physiological aging were used as model animals, and three groups were established: the tooth extraction, control, and young-age groups. In the tooth extraction group, all bilateral upper molar teeth were extracted at 18 months of age (presenium) and theanimals were sacrificed at 24 months. In the control group, animals were treated with anesthesia alone at 18 months and sacrificed at 24 months. Animals in the young-age group were untreated and were sacrificed at 6 months. Each group consisted of 3 mice. Total RNA was extracted from the hippocampal tissueand subjected to microarray analysis.
Results: Changes in expression with aging occurred in 76 genes: expression increased in 31 genes anddecreased in 45 genes. Tooth extraction-induced expression changes were found in 59 genes: expressionincreased in 49 genes and decreased in 10 genes. In all 15 genes that showed changes in expression with aging and toothextraction, expression was reduced with aging and increased by tooth extraction.
Conclusion: In the mouse hippocampus, aging and tooth extraction induce different changes in geneexpression, suggesting that loss of molar teeth has an influence on gene expression levels in the hippocampus, but does not promote aging.
