Inhibition of relaxin-induced pubic symphyseal "relaxation" in guinea pigs by glycosaminoglycan polysulfates and pentosan polysulfate.

There are similarities between the actions of estrogen and relaxin on the connective tissues of the pubic symphysis and those of neutral proteases on cartilage in osteoarthritis, including cartilage hydration, proteoglycan loss, and dissolution of collagen fibers. We hypothesized that compounds known to inhibit cartilage breakdown in animal models of osteoarthritis, such as polysulfated GAGs, would also antagonize the actions of estrogen and relaxin that increase the laxity and mobility of the pubic symphyses of guinea pigs. Estrogen-primed guinea pigs were injected with relaxin or with relaxin and the test compound. The pubic symphyses were manually palpated 6 h later and the degree of mobility scored. Glycosaminoglycan polysulfates and pentosan polysulfate inhibited relaxin-induced pubic symphyseal relaxation, whereas other types of agents were without effect. The guinea pig pubic symphysis assay for relaxin may thus provide a novel rapid screening test for compounds with potential chondroprotective activity.