Objective To observe the effect of electroacupuncture(EA)serum on proliferation of multifidus muscle satellite cells(SCs)and expression of paired box transcription factor Pax-7

MyoD and protein kinase B(PKB or Akt)proteins of SCs

so as to explore its underlying mechanism in promoting repair of multifidus muscles.Methods Thirty-two SD rats were randomly assigned to control

model

EA-Weizhong(BL 40)and EA-Shenshu(BL 23)groups.The multifidus muscle injury(MFMI)model was established by injection of 0.5% bupivacaine hydrochloride(400μL)into the bilateral L4-L5 paravertebral muscles(4points

100μL for each point).EA stimulation was separately applied to bilateral BL 40 and BL 23 for 20min

once daily

4days altogether.Blood samples of the abdominal artery of rats in the above mentioned 4groups were separately collected for extracting serum

followed by deactivation and filtration

and then were respectively applied to the Dulbecco's Modified Eagle Media(DMEM)culturing each multifidus muscle SCs of the normal serum

model serum

EA-BL 40 serum and EA-BL 40serum+LY 294002(an inhibitor of phosphotidylinsitol-3-kinase

PI 3K)

EA-BL 23 serum and EA-BL 23serum+LY 294002 groups for analyzing the impact of EA serum on the proliferation state of SCs by Cell Counting Kit-8(CCK-8)and 5-Ethynyl-2'-deoxyuridine(EdU)methods

respectively.The expression of Pax-7

MyoD and phosphorylated(p)-Akt proteins of the cultured SCs was detected for characterization of SCs by Western blot.Results Compared with the normal serum group

the proliferation levels(detected by both CCK-8-and EdU)and the expression levels of MyoD and p-Akt proteins of SCs in the model serum group were significantly increased(P<0.05

P<0.01)

while in comparison with the model serum group

the proliferation and expression levels of MyoD and p-Akt proteins of SCs were further significantly increased in both EA-BL 23 and EA-BL 40 serum groups(P<0.01

P<0.05)

but not in the EA-BL 40serum+LY 294002 and EA-BL 23serum+LY 294002groups(P>0.05)

suggesting an involvement of PI 3Kin the proliferation of SCs.No marked differences were found in the proliferation levels between the EA-BL 23 and EA-BL 40 serum groups and in the expression levels of Pax-7proteins among the 6serum groups(P>0.05).Conclusion Both EA-BL 40 and EA-BL 23 serum can promote proliferation of multifidus muscle SCs

which may contribute to the effect of EA intervention in promoting repair of the injured muscle

partially by way of Akt/PI 3Ksignaling.