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Influences of reduced masticatory sensory input from soft-diet feeding upon spatial memory/learning ability in mice
Keisuke Tsutsui1, Masato Kaku, Masahide Motokawa
1Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan. kktt0821@hotmail.com
Abstract:
It has been reported that reduction of masticatory afferent stimulation might influence learning and memory function. In order to clarify the influences of reduced masticatory sensory input on spatial memory/learning ability and neuropathological changes, we conducted the Morris water maze experiment and investigated the number of hippocampal neurons in association with the differences in masticatory afferent stimuli from hard- and soft-diet feeding in mice. The water maze experiment showed no significant difference in learning ability between 180-day-old solid- and powderdiet groups. Meanwhile, the ability was significantly reduced in the 360-day-old powder-diet group as compared with the age-matched solid-diet group. The total number of pyramidal cells in the hippocampal CA1 and CA3 regions was significantly smaller in 360-day-old powder-diet group than in the remaining groups. These results demonstrate that reduction of masticatory afferent stimuli due to long-term soft-diet feeding may induce neuron loss in the hippocampus and reduced memory/learning ability.
Insights
Reduced chewing stimulation from soft diets may impair spatial memory and cause hippocampal neuron loss in older mice. This highlights the importance of masticatory input for cognitive function and brain health.
Area of Science:
- Neuroscience
- Gerontology
- Nutrition Science
Background:
- Masticatory afferent stimulation plays a potential role in cognitive functions, including learning and memory.
- Understanding the impact of reduced sensory input from chewing on brain health is crucial, especially with changing dietary patterns.
Purpose of the Study:
- To investigate the effects of reduced masticatory afferent stimuli on spatial memory and learning ability in mice.
- To examine associated neuropathological changes, specifically hippocampal neuron counts, in response to different diets.
Main Methods:
- Mice were fed either a hard (solid) or soft (powder) diet.
- Spatial learning and memory were assessed using the Morris water maze experiment at 180 and 360 days of age.
- The number of pyramidal cells in the hippocampal CA1 and CA3 regions was quantified.
Main Results:
- No significant difference in learning ability was observed between solid- and powder-diet groups at 180 days.
- A significant reduction in learning ability was found in the 360-day-old powder-diet group compared to the solid-diet group.
- The 360-day-old powder-diet group exhibited a significantly lower total number of hippocampal CA1 and CA3 pyramidal cells.
Conclusions:
- Long-term soft-diet feeding, leading to reduced masticatory afferent stimuli, may induce hippocampal neuron loss.
- This neuron loss is associated with impaired spatial memory and learning ability in aged mice.
- The findings underscore the link between chewing function, hippocampal integrity, and cognitive performance.
