Effect Of Paeoniflorin On The Polarization Of Spinal Microglia In Rats With Neuropathic Pain

Objective In this study,the chronic sciatic nerve compression injury model was established to observe the effect of paeoniflorin on the mechanical pain threshold and the thermal pain threshold,and the polarization of spinal microglia in rats.Methods Thirty-six SPF male SD rats,aged 5?6 weeks,weighing 180?200g,were randomly divided into 3 groups?n=12?using the random number table method:sham operation group?Sham group?,model group?CCI group?and paeoniflorin group?CCI+PF group?.By ligating the left sciatic nerve of rats,a classic chronic sciatic nerve compression injury?CCI?model was established.After the model was established successfully,the paeoniflorin(60 mg·kg^-1·d^-1)was injected intraperitoneally in the CCI+PF group,and 0.9%normal saline was injected intraperitoneally in the Sham group and CCI group for 14 days.The paw withdrawal mechanical threshold?PWMT?and the paw withdraw thermal latency?PWTL?of rats were measured respectively at 1d before surgery and at 3d,7d,10d,and 14d after surgery;On the 14th day after operation,6 rats in each group were randomly selected.The expressions of M1 type marker CD68 and M2 type marker CD206 of L4-6 segment of spinal cord of rats was detected by immunofluorescence;The expression of TNF-?,IL-1?and IL-10 in M1 and M2 type microglia of L4-6 segment of spinal cord were detected by ELISA.Results 1.The measurement results of PWMT and PWTL showed that there was no statistically significant difference between each group at 1d before surgery?P>0.05?;Compared with the Sham group,PWMT and PWTL were significantly reduced at all time points in the CCI group?P<0.001?;Compared with the CCI group,PWMT and PWTL were increased at 7 d,10 d,and 14 d after surgery in the CCI+PF group?P<0.05?.2.The results of immunofluorescence showed that compared with the Sham group,the expression of CD68 in the CCI group increased significantly?P<0.001?,and there was no significant difference in the expression of CD206?P>0.05?;Compared with the CCI group,the expression of CD68 in the CCI+PF group was reduced?P<0.05?,and the expression of CD206 was increased?P<0.05?.3.The results of ELISA showed that compared with the Sham group,the expression of TNF-?protein was significantly increased in the CCI group?P<0.001?,and the expression of IL-1?protein was also increased?P<0.01?,but there was no significant difference in the expression of IL-10 protein?P>0.05?;Compared with the CCI group,the expressions of TNF-?and IL-1?in the CCI+PF group were reduced?P<0.05?,and the expression of IL-10protein was increased?P<0.05?.Conclusion Paeoniflorin can relieve neuropathic pain in rats,and the mechanism may be related to the regulation of spinal microglia polarization.