Objective To observe the effect of electroacupuncture(EA)stimulation on the expression of metalloproteinase-9(MMP-9)and tissue inhibitor-1(TIMP-1)in the lung tissue in rats with chronic obstructive pulmonary disease(COPD)

so as to reveal its mechanisms in protecting the lung tissue.Methods Forty male SD rats were equally randomized into control

model

medication and EA groups.The COPD model was established by smoke-fumigation method(passive smoking in a closed box)and endotracheal injection of lipopolysaccharide(200μg/100μL)for 30 days.Rats of the medication group were treated by i.p.of dexamethasone acetate injection(2.0mg/kg)

once daily for 22 days.EA was applied to LU 9

ST 36

ST 40 and KI 3for 20 min

once daily for 22 days.Pathological changes of the pulmonary tissue were observed under optical microscope after hematoxylin and eosin(H.E.)staining.The expression of pulmonary MMP-9and TIMP-1was assayed by immunohistochemistry.Results H.E.staining showed pulmonary diffuse edema

severe inflammatory cell infiltration

and increase of the numbers of goblet cells

proliferation of fibroblasts

etc.in the model group which were relatively milder in the medication and EA groups.The expression levels of pulmonary MMP-9and TIMP-1proteins were significantly higher in the model group than in the control group(P<0.05)

and were considerably down-regulated in both EA and medication groups in comparison with the model group(P<0.05).There were no significant differences between the EA and medication groups in MMP-9and TIMP-1expression levels(P>0.05).Conclusion EA can effectively suppress the increased expression of pulmonary MMP-9and TIMP-1in COPD rats

which may contribute to its effect in improving COPD-induced pathological changes.