The Effects of Age and Sex on the Expression of Aromatase in the Rat Temporomandibular Joint

Aims: To investigate the expression of aromatase in temporo-mandibular joints(TMJs) of male and female rats of different ages. Methods: The expression of aromatase in terms of protein and mRNA was examined by immunohistochemistry, Western blot, and in situ hybridization in the TMJs of Sprague-Dawley rats. The expression level of aromatase protein was also quantified by the density of aromatase-positive chondrocytes in TMJ condylar carti-lage. A tritiated water assay was used to analyze the activity of aromatase in cartilage chondrocytes. Results: Strong aromatase protein and mRNA hybridization signals were detected in hyper-trophic and mature chondrocytes in all the cases examined. The density of aromatase-positive chondrocytes was relatively stable at higher levels before 8 weeks of age. The density decreased gradu-ally in females after 8 weeks of age but not in males. Conclusion: These results demonstrate that aromatase is expressed intensely in condylar cartilage and suggest that it may play an important role in pathophysiological mechanisms in condylar cartilage.

aromatase; cartilage; chondrocytes; estrogen; temporo-mandibular joint

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