Influence of Recovery of Masticatory Stimulation on the Hippocampus in the Senescence-Accelerated Mouse P8

Abstract

We found that a reduction in masticatory stimulation due to raising mice on powder feed, leads to an early decline in learning and memory ability, which is a core symptom of dementia. Therefore, we used the senescence-accelerated mouse P8 to histopathologically investigate how the hippocampus is affected by a restoration of masticatory stimulation changing from powder to solid feed during the feeding period. The experimental groups comprised a group raised up to age 5 months and a group raised up to age 7 months. The mice were divided into four groups: a group raised solely on solid feed, a group that was changed from powder to solid feed at age 3 months, a group that was changed from powder to solid feed at age 5 months, and a group raised solely on powder feed. After raising mice on these types of feed, brain slices of each mouse were obtained and Nissl staining was performed. The pyramidal cell count and cell surface area were then determined. Results suggested a trend in which changing from powder to solid feed and a restoration of masticatory stimulation prevents a reduction in the hippocampal pyramidal cell count. We consider that the restoration of masticatory stimulation in the early stage is important in the prevention of dementia.