不同电压脉冲射频对慢性坐骨神经压迫损伤大鼠模型下丘脑 β-内啡肽的影响

摘要

目的:观察不同电压脉冲射频(pulsed radiofrequency,PRF)对慢性坐骨神经压迫损伤(chronic constriction injury,CCI)大鼠模型下丘脑 β-内啡肽含量的影响,探讨脉冲射频的镇痛机制.方法:雄性SD大鼠72只建立CCI疼痛模型后,随机分为4组(n=18):假刺激组H0、PRF低电压组H1(45 V)、PRF中电压组H2(55 V),PRF高电压组H3(65 V).PRF组:制模后7 d对其坐骨神经结扎近端行PRF,脉宽20 ms,频率500 kHz,脉冲频率2 Hz,持续时间2 min,治疗电压分别为45 V、55 V、65 V.假刺激组:制模后7 d在相同位置放置射频电极,但无脉冲治疗,持续时间2 min.制模前、制模后7 d、PRF后1、7和14 d测定大鼠疼痛行为学变化.PRF后1、7和14 d,每组各处死6只大鼠,测定不同时间点大鼠下丘脑中 β-内啡肽表达量.结果:脉冲射频组在治疗后1天、7天和14天,与假刺激组比较,热痛阈均明显提高(P<0.01).其中术后第7日,中、高电压组明显高于低电压组,差异具有统计学意义(P<0.01);在实验结束时,与假刺激组大鼠比较,术后第1天,7天和14天,低、中、高电压组大鼠下丘脑 β-内啡肽含量明显升高(P<0.01);术后第7、14天,与低电压组相比,中、高组大鼠下丘脑 β-内啡肽含量明显升高(P<0.01);术后第14日,高电压组与中电压组相比,存在显著差异(P<0.01).结论:电压45 V、55 V、65 V的2 Hz脉冲射频均可引起CCI大鼠热痛阈的升高,可能与其增加下丘脑 β-内啡肽的含量有关;脉冲射频电压大于55 V时,治疗效果没有进一步改善.%Objective: To observe the effect of different voltage pulsed radiofrequency (PRF) on the content of beta-endorphin in the hypothalamus of CCI rat model, and to explore the analgesic mechanism of pulsed radiofrequency. Methods: Seventy-two male SD rats were randomly divided into 4 groups (n=18): Sham operation group H0, PRF low voltage group H1 (45 V), PRF medium voltage group H2 (55 V), PRF high voltage group H3 (65 V). All rats underwent chronic constriction injury of sciatic nerve. On the 7th postoperative day in PRF groups, PRF was delivered with a pulse duration of 20 ms (500 kHz) and pulse rate of 2 Hz to the proximal sciatic nerve for 2 min. The treatment voltage was 45 V, 55 V and 65 V respectively;While in H0 group, PRF needles were placed in the proximal sciatic nerve for 2 min without radiofrequency current. Pain behavioral changes were measured before operation, 7 days after operation, and 1, 7, 14 days after PRF treatment. The expression of beta-endorphin was measured in the hypothalamus of CCI rat (n=6) in each group at l, 7, 14 days after PRF treatment. Results: At 1, 7, 14 days after PRF treatment, paw withdrawal thermal latency (PWTL) of PRF groups were all increased significantly comparing with sham operation group (P < 0.01). On the 7th day after the operation, PWTL of the medium and high voltage group was significantly higher than the low voltage group (P < 0.01). At the end of the experiment, the expression of beta-endorphin in PRF groups were significantly higher than sham operation group (P < 0.01). On the 7th day and 14th after the operation, the expression of beta-endorphin of the medium and high voltage group were increased significantly comparing with the low voltage group (P < 0.01). On the 14th day after the operation, there were differences between medium and high voltage group (P < 0.01). Conclusion: PRF (frequency 2 Hz) of the low, medium and high voltage group can all cause the increase of the PWTL of CCI rats, which may be related to the increase of the content of beta-endorphin in the hypothalamus. When the pulsed radiofrequency voltage is greater than 55V, the treatment effect is not improved further.