Effects of chondroitin sulfate-C on bradykinin-induced proteoglycan depletion in rats

Depletion of the proteoglycan content of articular cartilage was induced by injecting bradykinin (30-300 mu mol/l, 50 mu l/knee) into the left knee articular cavities of rats 3 times a day for 2 days. The degree of the reduction in the intensity of histopathological safranin O staining was used as an index of proteoglycan depletion. Bradykinin reduced the cartilage proteoglycan contents of the knee joints of non-injected limbs in a dose-dependent manner and at 300 mu mol/l markedly reduced these contents, but evoked no inflammatory changes. The extent of the reduction of the cartilage proteoglycan contents induced by bradykinin injection depended on the dose and injection frequency. Chondroitin sulfate-C (CAS 25322-46-7, Chondroitin ZS Tab) (30-1,000 mg/kg/day) administered orally to rats for 14 days inhibited the bradykinin-induced proteoglycan depletion of the articular cartilage in a dose-dependent manner. These results suggest that a reduction of the proteglycan content of cartilage, like that associated with osteoarthritis, was induced by injecting bradykinin into the knee articular cavities of rats and chondroitin sulfate-C protected against this effect.