Objective To observe the effect of electroacupuncture(EA) or manual acupuncture of unilateral or bilateral "Zusanli"(ST 36) on the contents of serum inflammatory factors interleukin-1β(IL-1β) and tumor necrosis factor-α(TNF-α)

and anti-inflammatory factors interleukin 2(IL-2)

interleukin 4(IL-4) and interleukin 10(IL-10)

so as to reveal their mechanism underlying improvement of chronic arthritis.Methods Sixty SD rats were randomly divided into normal control

model

electroacupuncture(EA)-left(L) Zusanli(ST 36)

EA-bilateral(Bi)-ST 36

and manual acupuncture(MA)-L-ST 36 groups(12 rats/group).Arthritis model was established by subcutaneous injection of complete Freund's adjuvant(0.1 mL)into the hindpaw.EA(2 Hz/100 Hz

1-3 mA

pulse duration: 0.6 ms/0.2 ms) or manual needle stimulation was applied to the left or bilateral "Zusanli"(ST 36) for 30 min

twice every week for 4 weeks.Enzyme linked immunosorbent assay(ELISA) was used to detect the contents of serum IL-1β

TNF-α

IL-2

IL-4 and IL-10

respectively.Results Compared with the normal control group

the contents of serum inflammatory factors IL-1β and TNF-α

anti-inflammatory factors IL-4 and IL-10 were increased significantly in the model group(P<0.001).In comparison with the model group

serum IL-1β

TNF-α

IL-4 and IL-10 contents were down-regulated considerably in the EA-L-ST 36

EA-Bi-ST 36 and MA-L-ST 36 groups(P<0.001

P<0.005).Serum IL-2 content had no apparent changes after modeling in comparison with the normal group(P>0.05).While serum IL-2 contents were markedly higher in the EA-L-ST 36

EA-Bi-ST 36 and MA-L-ST 36 groups than in the model group(P<0.05).No significant differences were found among the EA-L-ST 36

EA-Bi-ST 36 and MA-L-ST 36 groups in serum IL-1β

TNF-α

IL-2

IL-4 and IL-10 contents(P>0.05).Conclusion EA or manual acupuncture stimulation of single or bilateral ST 36 can effectively down-regulate serum inflammatory factors IL-1β and TNF-α levels

and upregulate anti-inflammatory factor IL-2 level in chronic arthritis rats

which may contribute to their effects in relieving chronic arthritis.