| Objectives : To prepare a rat model of postherpetic neuralgia(PHN)by intraperitoneal injection of resin toxin(RTX),and observe the effect of pulsed radiofrequency(PRF)intervention on post-herpetic neuralgia rats.Analgesic effects and mechanisms explore the possible role of PINK1/Parkin signaling pathway and mitochondrial autophagy in its therapeutic mechanisms.Methods:There were 60 SPF healthy adult male SD rats weighing 200-220 g.Sixty SD rats were randomly divided into Blank group,V-C group,PHN group,Sham PRF group and PRF treatment group,with 12 rats in each group.Blank group: intraperitoneal injection of normal saline according to the same volume of PHN group;V-C group: freshly prepared a mixture of 10%Tween 80,10% ethanol and 80% physiological saline,intraperitoneal injection according to the same volume of PHN group;PHN group,Sham PRF group,PRF treatment group: intraperitoneal injection according to RTX 200ug/kg.2 h before RTX treatment,1 d,4 d,7 d,10 d,14 d after RTX treatment,and 1 d,4 d,7 d,10 d,14 d,21 d,28 d,35 d,42 d after PRF treatment The rats were subjected to mechanical mechanical withdrawal threshold(PMWT)and thermal withdrawal latency(TWL)for 42 days.Sham PRF group: After intraperitoneal injection of RTX,PRF puncture was performed after the mechanical contraction threshold and heat-shrinking latency of the rats were stabilized,but PRFtreatment was not performed.PRF treatment group: after intraperitoneal injection of RTX,the rats were treated.PMWT and TWL were stabilized and PRF puncture was performed and PRF was given.In PHN group,no other treatment was given after intraperitoneal injection of RTX.After measuring PMWT and TWL on the 35 th day after PRF treatment,the spinal cord tissues of L4~L6 segments of each group were taken,and the spinal cord tissue proteins PINK1,Parkin,Lc3 II,Lc3I,Becline-1 and the segment were determined by western blotting.The expression level of P62 was detected by RT-qPCR.The expression of Becline-1 and Lc3 mRNA in spinal cord tissue was detected by transmission electron microscopy.The number of autophagosomes and mitochondrial morphology of spinal cord tissue were observed by transmission electron microscopy.Results:1.Mechanical pain threshold test results: Compared with the Blank group,the PHN group had a significant decrease in the mechanical pain threshold in the Sham PRF group(P<0.05).Compared with the PHN group,the RTX after 1 day after the PRF treatment.The mechanical pain threshold of rats in the-PRF group began to increase,and the mechanical pain threshold at each time point was significantly higher than that in the PHN group(P<0.05).2.Thermal pain threshold test results: Compared with the Blank group,the PHN group had a significantly higher thermal pain threshold in the Sham PRF group(P<0.05).Compared with the PHN group,1 day after the PRF treatment.The mechanical pain threshold of the rats in the PRF treatment group began to decrease,and the mechanical pain threshold at each time point was significantly lower than that in the PHN group(P<0.05).3.Western blot analysis: Compared with the Blank group,the relative expression of protein PINK1 and Parkin in the spinal cord of PHN group and Sham PRF group increased significantly(P<0.05);and PHN group,Sham PRF group The relative expression of protein PINK1 and Parkin in the spinal cord of rats in the PRF treatment group was significantly lower(P<0.05).Compared with the Blank group,the ratio of Lc3II/Lc3 I in the spinal dorsal horn of rats in the PHN group was increased.Becline-1 The expression of SQSTM1/P62 was decreased(P<0.05),and there was no significant difference between the two groups.Compared with the PHN group,the ratio of Lc3II/Lc3 I in the spinal dorsal horn of rats in the PRF treatment group was decreased.Becline-1expression decreased,P62 expression increased(P <0.05),and there was no significant difference with Sham PRF group.4.RT-qPCR results: Compared with the Blank group,the Lc3 mRNA and the expression of mRNA Becline-1 in the spinal cord dorsal horn were increased in the PHN group(P<0.05).Compared with the PHN group,the PRF treatment group was larger than the PHN group.The mRNA Lc3 of the spinal dorsal horn was decreased,and the expression of mRNA Becline-1 was decreased,which was not significantly different from that of the Sham PRF group.5.Transmission electron microscopy observation: The spinal dorsal horn cells of the blank group were intact,no obvious autophagosomes were found,and the mitochondria structure was good.Compared with the Blank group,more complete autophagy appeared in the spinal dorsal horn of the PHN group.Small body double membrane structure,mitochondrial swelling,vacuolar degeneration and extreme disappearance were obvious,and a few appeared to fuse with lysosome.Compared with PHN group,PRF treatment group had rare autophagy double-mode in spinal dorsal horn.Structure,mitochondria occasionally mildswelling and vacuolar degeneration,no significant disappearance and fusion with lysosomes.Conclusion:1.The mechanical pain threshold of rats in PHN model increased,the thermal pain threshold decreased,accompanied by increased expression of PINK1,Parkin in spinal cord tissue,enhanced autophagy activity,mitochondrial degeneration and apoptosis.2.PRF may inhibit the autophagy activity of mitochondria and improve the apoptosis of spinal cord tissue by inhibiting the activity of PINK1/Parkin signaling pathway in the spinal cord of rats with PHN model,and then analgesic effect on PHN model rats. |
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