Objective: To observe the effect of electroacupuncture (EA) serum on proliferation of multifidus muscle sa-tellite 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 (400 μL) into the bilateral L4-L5 paravertebral muscles (4 points, 100 μL for each point). EA stimulation was separately applied to bilateral BL 40 and BL 23 for 20 min, once daily, 4 days altogether. Blood samples of the abdominal artery of rats in the above mentioned 4 groups 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 40 serum+LY 294002 (an inhibitor of phosphotidylinsitol-3-kinase, PI 3 K), EA-BL 23 serum and EA-BL 23 serum+LY 294002 groups for ana-lyzing 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 40 serum+LY 294002 and EA-BL 23 serum+LY 294002 groups (P>0.05), suggesting an involvement of PI 3 K in 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-7 proteins among the 6 serum groups (P>0.05).
Conclusions: 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 3 K signaling.