Integrative and Comparative Biology Advance Access published online on June 18, 2008
Integrative and Comparative Biology, doi:10.1093/icb/icn050
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Using "Mighty Mouse" to understand masticatory plasticity: myostatin-deficient mice and musculoskeletal function
*Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA; Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912, USA
Correspondence: 1E-mail: ravosam{at}missouri.edu
Knockout mice lacking myostatin (Mstn), a negative regulator of the growth of skeletal muscle, develop significant increases in the relative mass of masticatory muscles as well as the ability to generate higher maximal muscle forces. Wild-type and Mstn-deficient mice were compared to investigate the postnatal influence of elevated masticatory loads due to increased jaw-adductor and bite forces on the biomineralization of mandibular articular and cortical bone, the internal structure of the jaw joints, and the composition of temporomandibular joint (TMJ) articular cartilage. To provide an interspecific perspective on the long-term responses of mammalian jaw joints to altered loading conditions, the findings on mice were compared to similar data for growing rabbits subjected to long-term dietary manipulation. Statistically significant differences in joint proportions and bone mineral density between normal and Mstn-deficient mice, which are similar to those observed between rabbit loading cohorts, underscore the need for a comprehensive analysis of masticatory tissue plasticity vis-à-vis altered mechanical loads, one in which variation in external and internal structure are considered. Differences in the expression of proteoglycans and type-II collagen in TMJ articular cartilage between the mouse and rabbit comparisons suggest that the duration and magnitude of the loading stimulus will significantly affect patterns of adaptive and degradative responses. These data on mammals subjected to long-term loading conditions offer novel insights regarding variation in ontogeny, life history, and the ecomorphology of the feeding apparatus.
From the symposium "Building a Better Organismal Model: The Role of the Mouse" presented at the annual meeting of the Society for Integrative and Comparative Biology, January 2–6, 2008, at San Antonio, Texas.