The effects of manipulating the frequency and magnitude of mastication on systemic skeletal robusticity in mice

Abstract

We manipulated the frequency of mastication in rodents by housing 24 female mice (12 inbred, 12 outbred) in a 10C room. These mice ate nearly twice as much food than their controls housed at room temperature (22C). Another group housed at room temperature was fed a modified soft diet the consistency of cookie dough. The experiment began when the mice were 24–27 days of age and continued for 12 weeks. After sacrifice, the mice were skeletonized and their interparietal bone, along with right parietal, humerus and femur μCT scanned at 18 μm resolution. Mean, median and maximum total thickness of the parietal and interparietal bones, as well as mean thickness of the cortical and trabecular portions of each was determined. Geometric cross-sectional measures of strength were determined for the long bones. Mice in the cold room had expectedly higher masseter muscle masses relative to body size than the controls, which in turn had heavier masseters than the soft diet group. However, the only difference in cranial vault robusticity was between controls and the soft diet group in the CD1 mice. Cranial vault thickness was not correlated with postcranial robusticity in any group. Funding for this project provided by an NSF DDIG 0925793 and Wenner-Gren 8012 to LC. Grant Funding Source: NSF