经皮三叉神经刺激改善慢性偏头痛大鼠中枢敏化

External trigeminal nerve stimulation improves central sensitization in chronic migraine model rats

摘要:

目的：探究经皮三叉神经刺激（external trigeminal nerve stimulation, eTNS）对硝酸甘油（NTG）诱导的慢性偏头痛（chronic migraine, CM）大鼠的作用及其潜在的机制。 方法：将SPF级SD雄鼠随机分为7组（n=12）：对照组、模型组、模型+假刺激组、模型+低频段低强度组、模型+高频段低强度组、模型+低频段高强度组、模型+高频段高强度组。采用腹腔隔日重复注射NTG建立CM模型。Von frey纤维丝检测眶周及后足机械痛阈值，热痛刺激仪检测热痛阈值，明确eTNS对CM的作用及最佳参数；Western Blot和免疫荧光检测三叉神经脊束核尾侧亚核（trigeminal nucleus caudalis, TNC）部位CGRP、c-fos、Iba-1及炎症因子表达情况，qRT-PCR检测不同分型小胶质细胞标志物。 结果：连续每天而不是间断的eTNS治疗可以提高CM大鼠的痛阈值，其中高频段低强度刺激效果最佳；eTNS治疗降低了TNC部位CGRP和c-fos的表达，抑制小胶质细胞的活化，减少炎症因子释放，并促进小胶质细胞由促炎的M1型向抗炎的M2型转化。 结论：eTNS对CM具有预防和急性止痛作用，刺激参数以高频段低强度为最佳，其作用机制可能与抑制小胶质细胞活化及其介导的免疫炎症有关。

Abstract:

Objective To explore the effect and potential mechanism of external trigeminal nerve stimulation (eTNS) on chronic migraine (CM) rats induced by nitroglycerin (NTG). Methods SPF-grade male SD rats were randomly divided into 7 groups (n=12): control group, model group, model + sham stimulation group, model + low-frequency low-intensity group, model + high-frequency low-intensity group, model + low-frequency high-intensity group, and model + high-frequency high-intensity group. The CM model was established by repeated intraperitoneal injections of NTG every other day. In order to determine the effect of eTNS on CM and the optimal parameters, Von frey fiber was used to detect the mechanical pain threshold of the periorbital and posterior foot, and the threshold of heat pain was detected by heat pain stimulator. The expression of CGRP, c-fos, Iba-1 and inflammatory factors in the caudal subnucleus of the trigeminal nucleus caudalis (TNC) was detected using Western Blot and immunofluorescence. QRT-PCR was applied to detect the expression of different types of microglia markers. Results Continuous daily rather than intermittent eTNS treatment can improve the pain threshold of CM rats, in which high-frequency low-intensity stimulation has the best effect. eTNS treatment decreased the expression of CGRP and c-fos in TNC, inhibited the activation of microglia, reduced the release of inflammatory factors, and promoted the transformation of microglia from pro-inflammatory M1 type to anti-inflammatory M2 type. Conclusion eTNS has preventive and acute analgesic effects on CM, and the optimal stimulation parameters are high frequency and low intensity. The mechanism may be related to the inhibition of microglia activation and immunoinflammation mediated by it.