Icariin

Background
Icariin (ICA) is an active compound extracted from Epimedium brevicornum Maxim. Icariin has been reported to have a clinically significant therapeutic effect on rheumatoid arthritis. However, the mechanism by which icariin prevents cartilage and bone degradation has been less explored.
Methods
New Zealand rabbits were immunized with antigen-induced arthritis (AIA) and treated with icariin for 3 months. Arthritis cartilage from rabbits were prepared for histological analysis, distal femur were scanned using micro-CT. Chondrocytes were observed using transmission electron microscopy (TEM). Rreceptor activator of nuclear factor-B ligand (RANKL) and osteoprotegerin (OPG) protein and mRNA expression in joint tissues as shown by immunohistochemistry and real time PCR analysis.
Results
Hematoxylin and eosin stain of cartilage in the

Indomethacin was used as a positive control. Each tablet contained 25 mg indomethacin was purchased from Shanghai Xinyi Pharmaceutical Co. Ltd., China. New Zealand rabbits with a body weight of 2–2.5 kg, were obtained from the Shanghai Laboratory Animal Center of the Chinese Academy of Sciences.
AIA rabbits were induced as in previous studies [24]. Briefly, We induced AIA rabbits by immunizing them with 4 mg ovalbumin (OVA) in Freund’s complete adjuvant (Sigma Chemical Co., St. Louis, MO, USA). This injection procedure was repeated once a week for 2 weeks, followed 4 weeks later by boosts with 1 ml of OVA once a week. Six weeks after the last booster injection, AIA rabbits were graded by scoring clinical signs according to criteria described in earlier studies [25]. The rabbits with clinical scores higher than six were deemed as having arthritis were randomly divided into three groups: The AIA group (n = 6), ICA group (n = 6) and control group (n = 6). The normal group rabbits (n = 6) did not undergo a