[Effect of moxibustion at "Zusanli" (ST36) on amino acid metabolism of knee cartilage in KOA rats].

Objective: To observe the effect of moxibustion at "Zusanli" (ST36) on amino acid metabolism of knee cartilage in the rats with knee osteoarthritis (KOA), and explore the mechanism of moxibustion for alleviating KOA cartilage injury. Methods: Thirty male SD rats were randomly divided into a normal group, a model group, and a moxibustion group, 10 rats in each one. The KOA models were prepared by injecting the mixed solution of L-cysteine and papain into the bilateral knee joint cavities of rats in the model group and the moxibustion group. In the moxibustion group, moxibustion was applied to bilateral "Zusanli" (ST36), 30 min each time, once daily and for consecutive 30 days. Before and after modeling, as well as after intervention, the knee joint diameter was measured. After intervention, the mechanical pain threshold was detected, the morphology of the cartilage tissue in the knee joint was observed using HE staining, and the ultrastructure of chondrocytes was observed under transmission electron microscopy; the levels of matrix metalloproteinase-13 (MMP-13) and interleukin-1β (IL-1β) in synovial tissue were detected using ELISA and the expression of cartilage amino acid metabolites was detected using liquid chromatography-mass spectrometry (LC-MS). Results: