Objective To observe the effect of electroacupuncture(EA) of “Zusanli”(ST36) and “Guanyuan”(CV4) on the apoptosis rate of synoviocytes and protein expression of Fas

FasL and Caspase-3 in synovial tissue of adjuvant-induced arthritis(AIA) rats

so as to explore its mechanisms underlying improvement of rheumatoid arthritis(RA). Methods A total of 24 rats were randomly divided into normal

model

medication and EA groups

with 6 rats in each group. The AIA model was established by injection of complete Freund's adjuvant(CFA

0.1 mL) into the left hindlimb paw. The rats in the medication group received intraperitoneal injection of 0.35 mg/kg of methotrexate

twice a week for 4 weeks. The rats in the EA group received EA stimulation of ST36 and CV4(20 Hz/50 Hz

1 mA) for 20 min

6 times a week for 4 weeks. The left hind paw volume was measured using a paw volume meter

and histopathological changes of synovial tissue were observed by light microscope after H.E. staining. The serum contents of tumor necrosis factor-α(TNF-α) and interleukin-1(IL-1) were measured by ELISA. The apoptosis of synoviocytes was detected by terminal-deoxynucleoitidyl transferase mediated nick end labeling(TUNEL)

and the expression of apoptosis-associated proteins Fas

FasL and Caspase-3 in synovium were detected by Western blot.Results Compared with the normal group

the left hind paw volume from day 3 to 24 after administration of CFA

serum IL-1 and TNF-α contents were significantly increased(P<0.01)

while the expressions of Fas

FasL and Caspase-3 proteins and apoptotic rate of synoviocytes were significantly decreased in the model group(P<0.01). In comparison with the model group

the paw volume from day 17 to 24 after modeling

the serum IL-1 and TNF-α contents were significantly reduced(P<0.01)

while the apoptotic rate of synoviocytes

expressions of Fas protein in both medication and EA groups

Caspase-3 protein in the acupuncture group and FasL protein in the medication group were increased(P<0.01

P<0.05). Compared with the medication group

the expression of FasL protein was decreased in EA group(P<0.05). H.E. stain showed obvious hyperplasia of the synovial lining layer

and disordered arrangement of synovial cells

with edema and enlargement in some cells in the model group

which was relatively milder in both medication and EA groups.Conclusion EA of ST36 and CV4 can promote the apoptosis of synoviocytes and the expressions of Fas and FasL proteins in AIA rats

which may contribute to its role in relieving synovitis through activating Fas/FasL signaling.