Differential expression of apoptosis-associated proteins in chondrocytes of the mandibular condyles of rabbits with anterior disk displacement.

Apoptosis is a potential contributor to anterior disk displacement (ADD) in temporomandibular joint disorders (TMD). The aim of this study was to investigate the expression of key protein regulators involved in apoptosis in the chondrocytes of mandibular condyles with induced ADD in experimental animals. ADD was surgically induced in the left temporomandibular joint (TMJ) of 15 rabbits without opening their bursas. A sham operation was performed on the right TMJ without displacing the disk forward. At the end of one, two, and four weeks after surgery, mandibular condyle samples were collected for protein extraction. The production of apoptosis-associated proteins Fas, capase-8, Bcl-2, and Bax was determined using Western blotting. The results indicate that the production of Fas and caspase-8 increased continuously after ADD. Meanwhile, the level of Bcl-2 decreased, and the production of Bax gradually increased following ADD. These results indicate that alterations in protein production of Fas, caspase-8, and the ratio of Bcl-2 to Bax are consistent with an increase of apoptotic activity in the chondrocytes, which may eventually lead to TMD.