Estrogen Receptor Beta Mediates Mechanical Loading Induced TMJ Remodeling

Objectives: TMJ predominantly afflicts women suggesting a role of estrogen in the diseases process. In long bones, estrogen via estrogen receptor beta inhibits mechanical loading induced periosteal bone formation. The goal of this project is to examine the role of estrogen receptor beta in mediating mechanical loading induced remodeling of the periosteal derived mandibular condylar cartilage
Methods: 49-day-old female WT (N=14) and ER beta KO mice (N=14) were divided into groups. The first group consisted of forced mouth opening of 0.5 N/1hr for 5 days and the second group served as control. Gene expression of chondrocyte maturation markers and proliferation were evaluated on the mandibular condylar cartilage from the different groups.
Results: Forced mouth opening caused an anabolic effect in the mandibular condylar cartilage from female WT mice that consisted of increased proliferation, increased Collagen type 2 expression, and increased Sox9 expression compared to control WT mice. In contrast, forced mouth opening did not cause any significant effect in proliferation or chondrocyte maturation markers (Sox9, Col2 or Col X) in female ER beta KO mice compared to control female ER beta KO mice.
Conclusions: Estrogen receptor beta is involved in the anabolic effects of mechanical loading in the mandibular condylar cartilage