OBJECTIVE

2

To investigate the improvement effect mechanism of Xibining prescription （XBN） on knee osteoarthritis （KOA） model rats based on AMP-activated protein kinase（AMPK）/mammalian target of rapamycin （mTOR） signaling pathway.

METHODS

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Totally 36 rats were randomly divided into blank group， model group， XBN group （12.56 g/kg）， XBN+metformin （AMPK agonist） group （12.56 g/kg XBN+100 mg/kg metformin）， with 9 rats in each group. Except for blank group， KOA model was induced by anterior cruciate ligament transection in other groups. After modeling， each group was given relevant medicine/normal saline， XBN and normal saline intragastrically， once a day， and metformin intraperitoneally， every other day， for 4 consecutive weeks. The pathomorphological changes of cartilage tissue in rats were observed and Mankin scoring was conducted. The expression level of Aggrecan in rat cartilage， mRNA and protein expressions of platelet reactive protein disintegrin and metalloproteinase with thrombospondin motifs 4 （ADAMTS-4）， ADAMTS-5， matrix metalloproteinase 3 （MMP-3） and MMP-13， and the phosphorylation level of AMPK and mTOR proteins were detected.

RESULTS

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Compared with blank group， the structure of cartilage tissue in the model group was disordered， the matrix of cartilage layer was lightly stained， the tide line was distorted or interrupted， and Mankin score was significantly increased （

P

＜0.05）. The protein expression of Aggrecan in cartilage tissue and the phosphorylation level of AMPK protein were all decreased significantly （

P

＜0.05）； mRNA and protein expressions of ADAMTS-4， ADAMTS-5， MMP-3 and MMP-13 and the phosphorylation levels of mTOR protein were significantly increased in cartilage tissues （

P

＜0.05）. Compared with model group， the pathological morphology of cartilage was improved significantly in each administration group， and above score or indexes were reversed significantly （

P

＜0.05）. Compared with XBN group， the degree of cartilage lesions in rats was further alleviated in XBN+ metformin group， and the levels of above score or indicators were further improved （

P

＜0.05）.

CONCLUSIONS

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XBN can ameliorate cartilage injury in KOA model rats， promote cartilage synthesis and reduce cartilage degradation， the mechanism of which may be associated with activating AMPK/mTOR signaling pathway.