Effect of electroacupuncture on PD-L1/PD-1-SHP-1 signaling pathway in dorsal root ganglia of rats with acute postoperative pain / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of electroacupuncture (EA) on programmed cell death ligand-1 (PD-L1)/programmed cell death receptor-1 (PD-1)/Src-homology region two domain-containing phosphatase-1 (SHP-1) signaling pathway in the dorsal root ganglia (DRG) of rats with acute postoperative pain.Methods:Thirty-nine SPF male Sprague-Dawley rats, weighing 220-250 g, aged 6-8 weeks, were divided into 3 groups ( n=13 each) using a random number table method: control group (group C), abdominal surgery group (group S) and abdominal surgery+ EA group (group S+ EA). Group S and group S+ EA underwent abdominal surgery under isoflurane anesthesia. In S+ EA group, both Zusanli and Sanyinjiao acupoints were selected and stimulated for 30 min with a frequency of 10 Hz continuous wave and a current of 1 mA starting from the end of operation and 2 h after operation. Seven rats were selected from each group for measurement of the mechanical paw withdrawal threshold (MWT), abdominal contraction threshold (ACT), thermal paw withdrawal latency (TWL) and cold paw withdrawal latency (CWL) at 1 day before developing the model (T 0) and 3, 5, 7, 9, 11 and 24 h after developing the model (T 1-6). Six rats in each group were sacrificed at 5 h after the model was prepared, and T 12-L 4 DRG was removed for determination of the expression of interleukin-6 (IL-6), PD-L1, PD-1 and SHP-1 (by Western blot) and expression of PD-L1 in various neurons (by immunofluorescence). Results:There was no significant difference in TWL and CWL between the three groups at different time points ( P>0.05). Compared with group C, MWT at T 1-5 and ACT at T 1-6 were significantly decreased, and the expression of IL-6 in DRG was up-regulated, and the expression of PD-L1, PD-1 and SHP-1 in DRG was down-regulated in group S ( P<0.05). Compared with group S, MWT and ACT were significantly increased at T 1, 2, the expression of IL-6 in DRG was down-regulated, and the expression of PD-L1, PD-1 and SHP-1 in DRG was up-regulated in group S+ EA ( P<0.05). The results of immunofluorescence showed that PD-L1 was expressed on both small diameter neurons (CGRP + neurons and IB4 + neurons) and large diameter neurons (NF200 + neurons) and mainly on CGRP + neurons and IB4 + neurons. There was no significant difference in the expression of PD-L1 in various DRG neurons among the three groups ( P>0.05). Conclusions:The mechanism by which EA relieves acute postoperative pain may be related to activation of the PD-L1/PD-1-SHP-1 signaling pathway in the DRG of rats.