Abstract: AIM: To investigate the effects of delydmepiandrosterone (DHEA on experimental osteoarthritis in rats.METHODS: Forty rats were randomly divided into four groups. Group A is normal control group Osteoarthritic models of rats were established by intraarticular injections of papain into the right knee joints of groups B, C and D. Then the right knee joints of rats in groups C and D, respectively, received 150μl intraarticular injections of DHEA at a concentration of 50μmol·L^-1 and 100μmol·L^-1 and the right knee joints of rats in groups A and B both received 150 ul physiological saline, twice weekly for five weeks. Six weeks laterall rats were sacrificed, and the articular cartilage was assessed by gross morphologic, histologic, biochemical and immunohistochemical methods.RESULTS: The cartilagedamage in groups C and D was much less than that ingroup B through observation under a surgical microscope.The Mankin s score, nitric oxide (NO) in the douche of articular cavity, malondialdehyde (MDA) in synoviumthe expression of matrix metalloproteinase^-1 and 9 in articular cartilage in groups C and D decreased in comparison with group B, and the for egoingndexes Ingroup Ddecreased signiticantly compared with group C. However the activities of superoxide dismutase (SOD) in thedouche of articular cavity and blood serumand D increased in comparison with group B, and the foregoing indexes in group D increased significantly compared with group C.CONCLUSIONS: DHEA shows acartilage-protecting effect which is in a dosage-dependentmanner. The mechanism probably is to inhibit the expression of matrix metalloproteinases and to decrease the release of (NO and enhance the antioxidation.

Key words: dehydroepiandrosterone, osteoarthritis, matrix metalloproteinases superoxide dismutase, malondialdehyde, nitric oxide