Arakawa Kyosuke, Kaku Ryuji, Kurita Masako, Matsuoka Yoshikazu, Morimatsu Hiroshi
Department of Anesthesiology and Resuscitology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama City, Okayama, Japan,
J Pain Res. 2018 Oct 30;11:2645-2651. doi: 10.2147/JPR.S168064. eCollection 2018.
Pulsed radiofrequency (PRF) is a safe and effective approach for treating neuropathic pain. However, the optimal treatment conditions and analgesic mechanisms of PRF remain unclear. The aim of our study was to assess the beneficial and adverse effects of prolonged-duration PRF and the analgesic mechanisms of PRF treatment with neuropathic pain rats.
Male Sprague Dawley rats received L5 spinal nerve ligation (SNL) for developing neuropathic pain. Fourteen days after L5 SNL surgery, they were divided into three groups according to duration of PRF current for 6 minutes, 12 minutes, and none. PRF current was delivered via direct visualization adjacent to the L5 dorsal root ganglion (DRG). Pain behavior was evaluated every week after L5 SNL surgery, until day 28. Seven days after PRF treatment, L5 DRG tissue was harvested to detect levels of activating translation factor 3 (ATF3; a marker of neuronal damage) and hyperpolarization-activated cyclic nucleotide (HCN)-gated cation channels (key factors in neuropathic pain) using quantitative PCR.
Before PRF application, withdrawal thresholds were significantly lower than at baseline and did not differ significantly between the three groups. After PRF application, withdrawal thresholds in the PRF6 and PRF12 groups were significantly increased compared to those in the sham group. However, those in the PRF6 and PRF12 groups did not differ significantly. The expression level of mRNA in the PRF12 group was significantly higher than that in the sham group (<0.01), but the expression of and channels did not differ significantly between the three groups.
Prolonged PRF exposure, from 6 to 12 minutes, was not only ineffective but also associated with increased neuronal damage. These findings do not support prolonged PRF exposure as a helpful treatment for neuropathic pain. In this study, the involvement of HCN channels in the antiallodynic effects of PRF was uncertain.
脉冲射频（PRF）是治疗神经性疼痛的一种安全有效的方法。然而，PRF的最佳治疗条件和镇痛机制仍不清楚。我们研究的目的是评估长时间PRF对神经性疼痛大鼠的有益和不良影响以及PRF治疗的镇痛机制。
雄性Sprague Dawley大鼠接受L5脊神经结扎（SNL）以诱发神经性疼痛。L5 SNL手术后14天，根据PRF电流持续时间分为三组：6分钟、12分钟和无PRF电流组。通过直接可视化在L5背根神经节（DRG）附近施加PRF电流。L5 SNL手术后每周评估疼痛行为，直至第28天。PRF治疗7天后，采集L5 DRG组织，使用定量PCR检测激活转录因子3（ATF3；神经元损伤标志物）和超极化激活环核苷酸（HCN）门控阳离子通道（神经性疼痛的关键因素）的水平。
在施加PRF之前，撤离阈值显著低于基线，且三组之间无显著差异。施加PRF后，PRF6组和PRF12组的撤离阈值与假手术组相比显著升高。然而，PRF6组和PRF12组之间无显著差异。PRF12组mRNA的表达水平显著高于假手术组（<0.01），但三组之间 和 通道的表达无显著差异。
将PRF暴露时间从6分钟延长至12分钟不仅无效，而且与神经元损伤增加有关。这些发现不支持延长PRF暴露时间作为神经性疼痛的有效治疗方法。在本研究中，HCN通道在PRF抗痛觉过敏作用中的作用尚不确定。
