Protective effects of equol on the cartilage and subchondral bone in ovariectomized rats with osteoarthritis

Objective(s): This study aimed to determine the therapeutic effect of equol (EQ) on osteoporotic osteoarthritis (OP OA). Materials and Methods: Thirty-six ۱۲-week-old female Sprague-Dawley rats were randomly divided into sham group, OP OA group, and EQ group (n=۱۲). OP OA was induced by anterior cruciate ligament transection (ACLT) combined with ovariectomy (OVX). EQ was orally administrated (۱۰ μg/g/day) after the operation for ۱۲ weeks. The efficacy was evaluated by gross pathology and histopathologic evaluation. The underlying mechanism was investigated by immunohistochemical analysis, micro-computed tomography (micro-CT) scanning, and tartrate-resistant acid phosphatase (TRAP) staining. Results: EQ effectively retarded cartilage degeneration, decreased the levels of matrix metalloproteinases-۱۳ (MMP-۱۳), a disintegrin and metalloproteinase with thrombospondin motifs ۵ (ADAMTS-۵), nuclear factor-kappa B P۶۵ (NF-κB P۶۵) and caspase-۳, and increased the levels of collagen type II (Col-II), Col-I, aggrecan (AGG), and inhibitor of NF-κB α (IκBα) in the cartilage. In addition, EQ increased bone mineral density, improved the microstructural parameters of the subchondral bone (SB), and decreased the number of osteoclasts. Conclusion: EQ exerted a chondroprotective effect on OP OA in rats, associated with inhibition of the NF-κB signaling pathway and chondrocyte apoptosis. Furthermore, EQ showed an osteoprotective effect on SB via inhibiting osteoclastic activities.

Keywords:

cartilage , Equol , Osteoarthritis , Ovariectomised rats , Subchondral bone