Meeting Abstract

P3.144  Wednesday, Jan. 6  Responses of Scapular Size and Shape to Exercise and Selective Breeding for High-Activity in Mus SCHUTZ, H*; ESCOBAR, R.A. III; GARLAND, T. Jr.; Univ. of California, Riverside; Loma Linda Univ.; Univ. of California, Riverside heidisc@ucr.edu

Various studies on rodent long bones show that chronic exercise produces a variety of osteological responses, including increased bone diameter and mass. Studies of skeletal responses to voluntary exercise in flat bones, such as the major girdle elements (e.g. scapula), are scarce, but show that scapular shape is also responsive to different types of exercise. A previous study used hindlimb bones of house mice selected (S) for high voluntary wheel running and non-selected controls (C) to examine responses to 8 weeks of wheel access and breeding for high activity (J. Morphology, 2006, 267:360-374). With body mass as a covariate, long bones showed significantly greater diameters and masses in response to both wheel access and selection. Additionally, S mice with the mini-muscle phenotype (50% reduction in hindlimb muscle mass) had longer, thinner long bones, but no differences in bone mass. Employing the same mice, we used geometric morphometrics to generate quantitative descriptors of scapular shape, centroid size, and a series of linear measurements from which we calculated ratios previously used to quantify scapular proportions. As previously reported, S mice were smaller in body length and mass than C, and access to wheels reduced body mass in both S and C mice. ANCOVA showed no differences between the S and C lines in scapular mass, centroid size, ratio of scapular mass/centroid size (SM/CS) or relative width. However, wheel access significantly increased scapular mass and SM/CS in both groups. Finally, S mice with the mini-muscle phenotype had significantly narrower scapulae, larger centroid sizes, and a smaller SM/CS. Supported by NSF IOB-0543429.