Meeting Abstract
LBS2.2 Thursday, Jan. 3 Using Mighty Mouse to understand masticatory plasticity: Myostatin-deficient mice and musculoskeletal function RAVOSA, M.*; NICHOLSON, E.; STOCK, S.; HAMRICK, M.; U Missouri-Columbia; Northwestern U; Northwestern U; Medical College of Georgia ravosam@missouri.edu
Knockout (KO) mice lacking myostatin (Mstn), a negative regulator of skeletal muscle growth, develop significant increases in relative jaw-adductor mass and can generate higher maximal muscle/bite forces. Wild-type and Mstn-deficient mice were compared to assess the postnatal influence of elevated masticatory stress on mandibular cortical bone and dental tissue plasticity. MicroCT was used to quantify tissue mineral density and internal structure at symphysis, corpus and TMJ coronal sections. Discriminant function analysis was used to characterize variation within and between loading cohorts. TMJ articular cartilage composition was evaluated histologically and immunohistochemically. In sum, 95% of Mstn-deficient mice and 95% of normal mice are distinguished based on mandibular tissue density values. KO mice had significantly more biomineralization on the outer surface of the TMJ condylar subchondral bone and along the condylar neck. Normal mice had symmetric subchondral bone surface contours. KO mice were asymmetric, with a less convex surface on the buccal vs. lingual side. Variation in TMJ cartilage anatomy appears to offset this buccal subchondral bone resorption. Cortical bone density at the corpus is higher in Mstn-deficient mice, but dental biomineralization is lower. KO mice exhibit significantly elevated density levels at the symphysis articular surface and external cortical bone. These differences appear due to the postweaning effects of increased masticatory loads in KO vs. wild-type mice, with the greater disparity of symphyseal values suggesting that this joint exhibits greater overall plasticity. Such findings underscore the benefits of a hierarchical and comprehensive perspective on the plasticity of masticatory tissues.
