Persistence and Modulation of PTH/PTHrP Receptor Expression in Hypertrophic Cells of Mandibular Condylar Cartilage from Ovariectomized and Estrogen-treated Ovariectomized Adult Rats

抄録

The expression of parathyroid hormone/parathyroid hormone-related protein (PTH/PTHrP) receptor in the mandibular condyles from sham-operated (Sham), ovariectomized (OVX), and OVX with 17 β-estradiol (E₂)-treated (OVX+E ₂) rats was investigated immunohistochemically with computer-aided image analysis. Western blot analysis for the receptor was also confirmed using these experimental cartilage models. The PTH/PTHrP receptor was preferentially localized in the hypertrophic chondrocytes throughout, and Western blot analysis revealed the protein expression in all of these cartilage models examined. Notably, OVX induced an enlargement of the hypertrophic chondrocytes, with larger indices of staining intensity and area as revealed by the image analysis; and E₂ treatment of OVX rats restored the values to nearly those of the Sham group. These findings suggest that the hypertrophic chondrocyte is a key regulatory site for the chondrocyte maturation and eventual matrix ossification in response to serum E₂ via the participation of PTH/PTHrP receptor in the adult rat mandibular condylar cartilage.