RESUMO
OBJECTIVE: We investigated the anti-inflammatory activity of strontium ranelate (SR) in arthritis models. MATERIALS AND METHODS: Rats received 1 mg zymosan (Zy) or saline intra-articularly. Other groups were subjected to anterior cruciate ligament transection in the right knee, as an osteoarthritis (OA) model, or a sham procedure. Joint pain was assessed using the articular incapacitation and paw-pressure tests. Cell influx and cytokines were measured in joint exudates. TREATMENT: Groups received either SR (30-300 mg/kg per os) or saline. RESULTS: SR dose-dependently and significantly inhibited joint pain in both Zy and OA models, while not altering cell influx. Naloxone administration significantly reversed SR analgesia. SR significantly reduced levels of Interleukin-1ß and tumor necrosis factor-α in Zy arthritis, whereas those of cytokine-induced neutrophil chemoattractant (CINC)-1 were not altered. CONCLUSIONS: SR provides analgesia in arthritis that is associated to inhibition of the release of inflammatory cytokines into inflamed joints. This effect is abrogated by administration of the opioid antagonist naloxone.