The COX-2 inhibitor etoricoxib reduces experimental osteoarthritis and nociception in rats: The roles of TGF-β1 and NGF expressions in chondrocytes.

Osteoarthritis (OA) is the most common joint disease, especially affecting the knee joint. Etoricoxib, a highly selective cyclooxygenase (COX)-2 inhibitor which can reduce postoperative pain after orthopedic surgery. The aim of this study was to investigate the effects of oral etoricoxib on the development of OA and to examine concomitant changes in the nociceptive behavior of rats.OA was induced in wistar rats by anterior cruciate ligament transection (ACLT) of the right knee. The ACLT + etoricoxib groups received 6.7 or 33.3 mg/kg of oral etoricoxib three times a week for 12 consecutive weeks, starting at week 8 after ACLT. Nociceptive behaviors and changes in knee joint width during OA development were analyzed. Histopathological studies were then performed on the cartilage. Immunohistochemical analysis was performed to examine the effect of etoricoxib on the expression of transforming growth factor-beta (TGF-β) and nerve growth factor (NGF) in articular cartilage chondrocytes.OA rats receiving etoricoxib showed a significantly lower degree of cartilage degeneration than the rats receiving placebo. Nociceptive behavior studies showed significant improvement in the ACLT + etoricoxib groups compared to that in the ACLT group. Moreover, etoricoxib attenuated NGF expression, but increased TGF-β expression, in OA-affected cartilage.Oral etoricoxib in a rat OA model (1) attenuates the development of OA, (2) concomitantly reduces nociception, and (3) modulates chondrocyte metabolism, possibly by inhibiting NGF expression and increasing TGF-β expression. This article is protected by copyright. All rights reserved.