Medialmeniscal tear (MMT) operation was performed in adult SD rats to induce OA. SR(625 or 1800 mg·kg?1·d?1) was administered via gavage for 3 or 6 weeks. Afterthe animals were sacrificed, articular cartilage degeneration was evaluatedusing toluidine blue O staining, SOX9 immunohistochemistry and TUNEL assay. Thechanges in microarchitecture indices and tissue mineral density (TMD), chemicalcomposition (mineral-to-collagen ratio), and intrinsic mechanical properties ofthe subchondral bones were measured using micro-CT scanning, confocal Ramanmicrospectroscopy and nanoindentation testing, respectively. The high-dose SRsignificantly attenuated cartilage matrix and chondrocyte loss at 6 weeks, anddecreased chondrocyte apoptosis, improved the expression of SOX9, a criticaltranscription factor responsible for the expression of anabolic genes type IIcollagen and aggrecan, at both 3 and 6 weeks. Meanwhile, the high-dose SR alsosignificantly attenuated the subchondral bone remodeling at both 3 and 6 weeks,as shown by the improved microarchitecture indices, TMD, mineral-to-collagenratio and intrinsic mechanical properties. In contrast, the low-dose SR did notsignificantly change all the detection indices of cartilage and bone at both 3and 6 weeks. The high-dose SR treatment can reduce articular cartilagedegeneration and subchondral bone remodeling in the rat MMT model of OA.
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