INVIVO EFFECTS OF NAPROXEN ON COMPOSITION, PROTEOGLYCAN METABOLISM, AND MATRIX METALLOPROTEINASE ACTIVITIES IN CANINE ARTICULAR-CARTILAGE

Naproxen is a nonsteroidal anti-inflammatory drug commonly use in the clinical treatment of joint disease. In this study, its effect in vivo on the biochemical composition, metabolic activities, and metalloprot einase activities of normal canine articular cartilage was analyzed. T he articular cartilage from the knee joints of dogs who had been given naproxen for 4 weeks to maintain a serum level of 40-50 mug/ml was ex amined. Control animals were given a placebo. Treatment with naproxen was not found to change the composition (water, collagen, and proteogl ycan) of the articular cartilage. The culture studies of cartilage exp lants indicated that proteoglycan synthesis rates were unaffected by t he treatment with naproxen but that proteoglycan release from the tiss ue was suppressed. Analysis of the cartilage for matrix metalloprotein ase activities showed reduced activity of neutral matrix metalloprotei nase by 80%, of collagenase by 40%, and of gelatinase by 87%, with no change in activity of acid metalloproteinase or of tissue inhibitor fo r metalloproteinase. These findings indicate that in vivo treatment wi th naproxen has the capacity to modulate catabolic activities in artic ular cartilage.