Abstract: BACKGROUND: The clinical application of Mongolian Medicine Erdun -uril in the treatment of osteoarthritis is effective, but its therapeutic effect and related mechanism are still unclear. 
OBJECTIVE: To observe the repairing process of osteoarthritis in rats by Mongolian Medicine Erdun-uril and analyze its mechanism.
Methods: Thirty male Sprague-Dawley rats (8 weeks of age) were selected to establsih an osteoarthritis model using intraarticular injection of sodium iodoacetate solution into the unilateral knee joint. Two weeks after modeling, the model rats were randomly divided into three groups: control group (n=6) was given normal saline by gavage, and low and high dose groups (n=12 per group) were given Erdun-uril 1.4 and 2 g, respectively, 3 times per day. After 2 and 4 weeks of continuous administration, blood samples, articular cartilage and periarticular bone tissue were taken from rats to detect changes in cartilage metabolic markers (cartilage oligomeric matrix protein, proteoglycan), bone metabolic markers (bone alkaline phosphatase, keratan sulfate), inflammatory markers (interleukin 6, tumor necrosis factor α), lipid metabolic markers (total cholesterol, triacylglycerol). Histopathological changes were also observed.
ResultS and CONCLUSION: qRT-PCR results showed that after 2 and 4 weeks of administration, the mRNA expression of cartilage oligomeric matrix protein, proteoglycan and bone alkaline phosphatase and keratan sulfate in knee cartilage of rats were significantly reduced in the low and high dose groups compared with the control group (P < 0.05, P < 0.01, P < 0.001), with the reduction being more significant in the high dose group. After 2 and 4 weeks of administration, compared with the control group, serum tumor necrosis factor α and interleukin 6 levels were decreased (P < 0.01, P < 0.001) and total cholesterol and triacylglycerol levels were increased (P < 0.05, P < 0.01, P < 0.001) in the low and high dose groups, with the improvement being more significant in the high dose group. Hematoxylin-eosin staining results showed that in the control group, there were large defective areas on the surface of the knee cartilage with unknown structure and severe inflammatory cell infiltration; in the low dose group, the surface of the knee cartilage was rough with disordered cell arrangement and the cartilage structure did not improve significantly after 2 weeks of administration, while the number of inflammatory cells in the knee cartilage was reduced and the cartilage structure was restored to some extent after 4 weeks of administration; in the high dose group, the structure of the knee cartilage become clear after 2 weeks of administration and even clearer after 4 weeks of administration, and the inflammation was significantly reduced after 2 weeks of administration. To conclude, Mongolian Medicine Erdun-uril with better anti-inflammatory properties can improve cartilage metabolism and obviously alleviate osteoarthritis in rats.

Key words: Mongolian Medicine, Erden-uril, osteoarthritis, cartilage metabolism, cartilage damage, rat