Objective To observe the effects of electroacupuncture on the paw withdrawal thresholds (PWTs) and the activation of satellite glial cells and their P2X7 receptors in the dorsal root ganglia (DRG) of the affected foot and plantar of rats with chronic inflammatory pain. To explore the peripheral mechanism of electroacupuncture against inflammatory pain in rats.
Method Part 1: The rats were completely randomly divided into blank group (Con group, n = 12), inflammatory pain group (CFA group, n = 12), inflammatory pain + electroacupuncture group (CFA+EA group, n = 12). Inflammatory pain + sham electroacupuncture group (CFA+sEA group, n = 12). Rats with inflammatory pain were subcutaneously injected with complete Freud's adjuvant (CFA) 0.1mL each in the middle of the right hind foot to construct a model; electroacupuncture treatment of the points "Zusanli" and "Kunlun", electroacupuncture parameters It is a density wave, frequency 2/100Hz, intensity 0.5-1-1.5mA (each intensity treatment 10min), once a day, continuous 7d. The mechanical pain threshold of rats in each group was detected before and after the modeling and 1, 3, 7, 8, 10, 12, and 14 days after the modeling, and the glial acidity in the DRG of the affected side of the rats in each group was detected by Western blotting 14 days after modeling. Protein (glial fibrillary acidic protein, GFAP) and P2X7 receptor activation. Part 2: Randomly divide the rats into inflammatory pain + DMSO group (CFA + DMSO group, n=8), inflammatory pain + P2X7R inhibitor A740003 group (CFA + A740003 group, n = 10), inflammatory pain + Electroacupuncture + saline group (CFA + EA + NS group, n=8), inflammatory pain + electroacupuncture + P2X7R agonist BzATP group (CFA + EA + BzATP group, n=12), respectively intrathecal injection corresponding drug. The changes of PWTs in rats were detected at each time point before operation, before modeling, after modeling and after administration.
Results (1) The pain threshold of CFA-induced inflammatory model rats was significantly decreased (P<0.01), and the mechanical pain threshold was significantly increased after electroacupuncture (P<0.01). 14 days after CFA plantar injection, the expression of GFAP and P2X7 protein in the L4-6 DRG of the ipsilateral side of the rat increased significantly (P<0.05); electroacupuncture significantly inhibited the expression of GFAP and P2X7 protein in the L4-6 DRG of the ipsilateral side of the rat (P<0.05). but="" there="" was="" no="" significant="" change="" in="" the="" sea="" group="" p="">0.05). (2) Compared with the CFA+DMSO group, intrathecal injection of the P2X7 inhibitor A740003 significantly increased the mechanical pain threshold of CFA rats (P<0.01); the PWTs in the CFA+EA+BzATP group were significantly lower than those in the CFA+EA+NS group ( P<0.01).
Conclusion Inhibiting the activation of rat dorsal root ganglion satellite glial cells and the expression of P2X7 receptor is involved in the anti-chronic inflammatory pain of electroacupuncture, which may be one of the peripheral mechanisms of electroacupuncture analgesia.