Oestrogen receptor beta mediates decreased occlusal loading induced inhibition of chondrocyte maturation in female mice

Abstract

ObjectiveTemporomandibular joint (TMJ) disorders predominantly afflict women, suggesting that estrogen may play a role in the disease process. Defects in mechanical loading-induced TMJ remodelling are believed to be a major etiological factor in TMJ degenerative disease. Previously, we found that, decreased occlusal loading caused a significant decrease in early chondrocyte maturation markers (Sox9 and Col 2) in female, but not male, C57BL/6 wild type mice (1). The goal of this study was to examine the role of Estrogen Receptor (ER) beta in mediating these effects. Design21-day-old male (n=24) and female (n=25) ER beta KO mice were exposed to decreased occlusal loading (soft diet administration and incisor trimming) for 4 weeks. At 49 days of age the mice were sacrificed. Proliferation, gene expression, Col 2 immunohistochemistry and micro-CT analysis were performed on the mandibular condyles. ResultsDecreased occlusal loading triggered similar effects in male and female ER beta KO mice; specifically, significant decreases in Col 10 expression, subchondral total volume, bone volume, and trabecular number. ConclusionDecreased occlusal loading induced inhibition of chondrocyte maturation markers (Sox9 and Col 2) did not occur in female ER beta deficient mice.