Changes in proteoglycan and collagen content in the mandibular condylar cartilage of the rabbit caused by an altered relationship between the condyle and glenoid fossa.

Twenty 5-day-old New Zealand rabbits underwent surgery to induce premature synostosis of the cranial sutures, resulting in posterior displacement of the glenoid fossa. Twenty sham-operated rabbits served as controls. The animals were killed at age 15 days for histochemical and biochemical analyses. The collagen content of the superior region of the condyle determined biochemically was lower in treated animals than in controls. Biochemical and histochemical analyses revealed the proteoglycan content to be significantly reduced in the superior region of the condyle (P < or = 0.001). Low levels of aggregating proteoglycans were seen. Since levels of aggregating proteoglycans decreased, catabolism must have exceeded their synthesis or the monomers must have been unable to aggregate and escaped from the tissue. It is concluded that an experiment in which the location of the mandibular condyle in the glenoid fossa is changed, while causing marked reductions in amounts of both collagen and proteoglycans in the cartilage tissue of the mandibular condyle, will also induce changes resembling those observed in animal models of arthritis. It is possible that the two phenomena have similar mechanisms.