We investigated the anti-inflammatory activity of strontium ranelate (SR) in arthritis models.
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.
Groups received either SR (30-300 mg/kg per os) or saline.
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-1β and tumor necrosis factor-α in Zy arthritis, whereas those of cytokine-induced neutrophil chemoattractant (CINC)-1 were not altered.
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.