In order to verify the influence of aging, tooth loss, and diet on bodily function, 216 old Donryu and Wistar male rats were divided into the following groups, the control group (fed solid diet), the soft diet group (fed powder diet containing the same components as solid one), the molarless group (all molars were removed at 45 weeks and then fed powder diet), the low calcium solid diet group (fed solid diet low in calcium and deficient in vitamin D) and the molarless low calcium diet group (all molars were removed at 45 weeks and then fed powder diet low in calcium and deficient in vitamin D). The histometric, exercise-physiologic, biochemical, and immunohistochemical analyses were performed.
The results were as follows:
1. The weight of the soft diet group at 75 weeks was higher than that of the control group at 75 weeks, showing statistical significance (p<0.01).
2. The adrenal gland weight of the Donryu rats in the molarless group 4 weeks after extraction was higher than that of the control group, showing statistical significance (p<0.01).
3. Occlusal support loss-and dietary-related changes were observed morphologically and histologically at the condyle and the attachment of the masseter muscle to mandible in addition to age-related changes.
4. The endurance performance (exhaustion time during swimming) and the value of serum indices (creatine phosphokinase and free-fatty acid) after swimming in aged rats were considerably influenced by occlusal and masticatory alteration in addition to aging.
5. The number of choline acetyltransferase (ChAT)-positive neurons in the nucleus of medial septal nucleus/nucleus diagonal of Broca of the molarless group showed decrease as compared to the control group and the soft diet group by immunohistochemical techniques. However, the number of neurons in the trigeminal motor nucleus showed no significant differences among the three groups.