Therapeutic effect and mechanism of action of quercetin in a rat model of osteoarthritis

Objective To study the therapeutic effect and mechanism of action of quercetin in a rat model of osteoarthritis (OA). Methods The OA rat model was established by intra-articular injection of papain. Changes in knee diameter, toe volume and histopathology were measured. Levels of interleukin (IL)-beta and tumor necrosis factor (TNF)-alpha were assessed by ELISA. Relative expression of Toll-like receptor (TLR)-4 and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappa B) was evaluated by western blotting. Results Compared with rats treated with papain alone, changes in knee diameter, toe volume and Makin' s score were less apparent in OA rats treated with quercetin. Levels of serum IL-1 beta and TNF-alpha were also reduced in quercetin-treated OA rats. Expression of TLR-4 and NF-kappa B was significantly suppressed in a dose-dependent manner in quercetin-treated OA rats. Conclusion Quercetin exhibited a therapeutic effect in OA rats, which may be related to inhibition of IL-1 beta and TNF-alpha production via the TLR-4/NF-kappa B pathway.