Objective

2

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

2

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

2

Compared with the normal group

in the model group

the cartilage surface of the knee joint was rough and dark

the cells appeared clustering

nuclear pyknosis and vacuolar degeneration

the endoplasmic reticulum was obviously reduced and abnormal in structure; the diameter of the knee joint increased (

P

<

0.01)

the mechanical pain threshold decreased (

P

<

0.05)

the contents of MMP-13 and IL-1β in the knee joint synovium were elevated (

P

<

0.01)

and the expression levels of proline

glycine

lysine

aspartate

alanine

methionine

and seri

ne in the knee joint cartilage rose (

P

<

0.05). When compared with the model group

in the moxibustion group

the injury of knee cartilage tissue was alleviated

the diameter of knee joint was reduced (

P

<

0.01)

and the mechanical pain threshold was elevated (

P

<

0.05); the contents of MMP-13 and IL-1β in knee joint synovium decreased (

P

<

0.05)

and the expression levels of proline

glycine

lysine

aspartate

histidine

glutamate in knee joint cartilage decreased (

P

<

0.05).

Conclusion

2

Moxibustion at "Zusanli" (ST36) alleviates joint swelling

pain

chondrocyte injury

and synovitis in KOA model rats; and exerts its anti-inflammatory

analgesic

and cartilage protective effect by modulating immune response and synthesis and degradation of cartilage in KOA through metabolic pathways of amino acids such as glycine

proline

aspartate and lysine.