Effect Of Pulsed Radiofrequency On Apoptosis Of Spinal Dorsal Horn In Rats With Postherpetic Neuralgia Model

Objectives:To investigate the effect of pulsed radio frequency(PRF)on apoptosis of spinal dorsal horn neurons in rats with postherpetic neuralgia(PHN),and to explore the possible role of apoptosis in spinal dorsal horn.Methods:Forty male SD rats weighing 200-240 g were randomly divided into five groups:blank control group(blank group),solvent group(solvent group),PHN model group(PHN group),sham treatment group(sham group)and treatment group(PRF group),with 8 rats in each group.Sham group,PRF group and PHN group were intraperitoneally injected with resiniferatoxin(RTX)0.2g/kg to prepare PHN model;blank group was intraperitoneally injected with the same volume of normal saline as PHN group;solvent group was intraperitoneally injected with the same volume of solvent(10%Tween 80,10%ethanol and 80%normal saline).Mechanical withdrawal threshold(MWT)and thermal withdrawal latency(TWL)were measured 2 hours before modeling,1,4,7,10,14,21,28 and 35 days after PRF treatment.The expression of Caspase-3,Bax and Bcl-2 in L4-6 spinal cord tissue was observed by immunohistochemistry;the number of apoptotic cells in spinal cord tissue was detected by TUNEL;the expression of Caspase-3,Bax and Bcl-2 in spinal cord tissue was detected by Western blot;the expression of caspase-3 mRNA and Bax mRNA was detected by RT-qPCR.Results:①after RTX treatment,the apoptosis of spinal cord cells increased in varying degrees;after PRF treatment,a large number of nuclei were found in spinal cord tissues,and the number of apoptosis decreased significantly.②Compared with blank group,MWT and TWL in PHN group,sham group and PRF group were significantly decreased,caspase-3 and Bax expression and protein content ratio were significantly increased,and bcl-2 protein content ratio was significantly decreased(all P<0.05).③Compared with PHN group,the MWT and TWL of PRF group were significantly increased,the expression and protein content ratio of Caspase-3 and Bax were significantly decreased,and the protein content ratio of Bcl-2 was significantly increased(all P<0.05).Conclusion:1.The mechanical pain threshold decreased and the thermal pain threshold increased in PHN model rats;2.The expression and protein content ratio of Caspase-3 and Bax in spinal cord of model rats were significantly increased,and the degree of apoptosis and mitochondrial degeneration were enhanced;3.The possible mechanism of PRF is to inhibit the apoptosis of rat spinal cord neurons.