Objective To observe the effect of electroacupuncture(EA) of “Zusanli”(ST36) and “Sanyinjiao”(SP6) on serum TNF-α

IL-1β

and IL-6 and expression of synovial matrimetalloproteinases(MMPs) and articular morphology in collagen-induced arthritis(CIA) rats

so as to explore its mechanisms underlying relief of arthritis. Methods Thirty male SD rats were randomly divided into normal control

CIA model and EA groups(n=10 rats per group). The arthritis model was induced by multi-point intradermal injection of bovine type Ⅱ collagen emulsion. EA(2 Hz/100 Hz

1 mA) was applied to bilateral ST36 and SP6 for 30 min

once a day for 28 days. The hind-limb paw volume was measured and the arthritis index(AI) score given according to the swelling degree

rigidity and deformity of the ankle joint(0—4 points). After EA intervention

the morphological damage of the affected ankle joints was revealed by H.E. staining

safranin O-fast green staining

and tartrate-resistant acid phosphatase(TRAP) staining

separately. The levels of serum TNF-α

IL-1β

and IL-6 were measured by ELISA

and the expression levels of MMP-1

MMP-3

MMP-13

and receptor activator of nuclear factor Kappa B ligand(RANKL) in the synovial tissue were detected by Western blot.Results Compared with the normal control group

the paw volume

AI score

TRAP-revealed number of osteoclasts

contents of serum TNF-α

IL-1β and IL-6

and expression levels of MMP-1

MMP-3

MMP-13 and RANKL proteins were significantly increased in the model group(P<0.01

P<0.05). Following the intervention

the paw volume

AI score

number of osteoclasts

contents of serum TNF-α

IL-1β and IL-6

and expression levels of MMP-1

MMP-3

MMP-13 and RANKL proteins were significantly decreased in the EA group(P<0.05

P<0.01) in contrast to the model group. H.E. and safranin O-fast green staining showed rough articular cartilage surface with thinned cartilage layer

obvious hyperplasia of the synovial tissue with many inflammatory cells

and serious damage and degradation of the cartilage matrix in the model group

these situations were relatively milder in the EA group. Conclusion EA of ST36 and SP6 can reduce the articular damage in collagen-induced arthritis rats

which is associated with its function in reducing inflammatory response and down-regulating the expression of synovial MMP-1

MMP-3

MMP-13 and RANKL proteins.