Background and objectives Pulsed radiofrequency (PRF) is a minimal neurodestructive interventional pain therapy. However, its analgesic mechanism remains largely unclear. We aimed to investigate the peripheral and spinal mechanisms of PRF applied either adjacent to the ipsilateral L5 dorsal root ganglion (PRF-DRG) or PRF to the sciatic nerve (PRF-SN) in the neuropathic pain behavior induced by chronic constriction injury (CCI) in rats.
Methods On day 0, CCI or sham surgeries were performed. Rats then received either PRF-DRG, PRF-SN, or sham PRF treatment on day 4. Pain behavioral tests were conducted before surgeries and on days 1, 3, 5, 7, 9, 11, 13, and 14. After the behavioral tests, the rats were sacrificed. The venous blood or sciatic nerve samples were collected for ELISAs and the dorsal horns of the L4–L6 spinal cord were collected for western blot examination.
Results The mechanical allodynia and the thermal hyperalgesia has been relieved by a single PRF-DRG or PRF-SN application. In addition, the analgesic effect of PRF-DRG was superior to PRF-SN on CCI-induced neuropathic pain. Either PRF-DRG or PRF-SN reversed the enhancement of interleukin 1β (IL-1β) and tumor necrosis factor alpha (TNF-α) levels in the blood of CCI rats. PRF-DRG or PRF-SN also downregulated spinal β-catenin expression.
Conclusions PRF treatment either to DRG or to sciatic nerve reduced neuropathic pain behavior, and reduced peripheral levels of pro-inflammatory cytokines and spinal β-catenin expression in CCI rats. PRF to DRG has a better analgesic effect than PRF to the nerve.
- pulsed radiofrequency
- neuropathic pain
- chronic constriction injury
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RJ and PL contributed equally.
Contributors RJ and PL contributed to animal experiments, analysis and interpretation of the data, and drafted the manuscript. YY, HL and RL contributed to animal experiments, analysis and interpretation of the data, and the writing of the manuscript. LH, SL, JY, LZ, ZP and L-PX contributed to molecular experiments, analysis and interpretation of the data, and the writing of the manuscript. XC contributed to the conception and design of the study, the analysis and interpretation of the data, and the writing of the manuscript. ZF supervised the study and contributed to the conception and design of the study. All authors approved the final version of the manuscript.
Funding This work was supported by National Natural Science Foundation of China (81671089, 81471127, 81603198), Zhejiang Medical and Health Platform Plan (2016ZDA006), Public Welfare Technology Application Research Project of Zhejiang Province (No. 2016C37104), Zhejiang Provincial Natural Science Foundation of China (No. LY19H090004), Ningbo Science and Technology Bureau Benefit People Project (2017C50043), Ningbo Natural Science Foundation (2018A610304) and Ningbo Municipal Innovation Team of Life Science and Health (2015C110026).
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as online supplementary information.