Objective: To observe the effects of electroacupuncture(EA) at "Fengchi"(GB20) on the ethology, microglia activation and P2X7 receptor(P2X7R) expression in the periaqueductal gray(PAG) in recurrent migraine rat model, so as to explore the underlying mechanism of EA reducing central sensitization of migraine.
Methods: Thirty-six male SD rats were randomly divided into control, model and EA groups, with 12 rats in each group. Recurrent migraine model was induced using repea-ted dural electrical stimulation once another day(the 1st, 3rd, 5th, 7th and 9th days), for a total of 5 times; rats in the EA group received EA treatment(2 Hz/15 Hz, 0.8-1 mA) at GB20 after dural electrical stimulation, for 10 min every time, once a day for 9 days; rats in the control group only received electrode placement. The facial and hindpaw mechanical withdrawal threshold was detected by using an electronic von-Frey on the 0th(baseline), 2nd, 4th, 6th, and 8th days. Microglia activation in the PAG was evaluated by using immunofluorescence staining to detect the number of ionized calcium binding adaptor molecule-1(Iba-1)-labeled microglia. Expression levels of microglia marker Iba-1, inflammatory factor interleukin(IL)-1β and P2X7R were detected by Western blot.
Results: Compared with the control group, the facial and hindpaw mechanical withdrawal threshold of rats were significantly reduced on the 2nd, 4th, 6th, and 8th days(P<0.01，P<0.001); the microglia in the PAG area were significantly activated, with the number of Iba-1-positive microglia, and the expression levels of Iba-1, IL-1β and P2X7R proteins significant increased(P<0.001, P<0.05) in the model group. Compared with the model group, the facial and hindpaw mechanical withdrawal threshold of rats were significantly increased on the 4th, 6th, and 8th days(P<0.05，P<0.001，P<0.01), and the above indicators were significantly reversed (P<0.05) in the EA group.
Conclusion: EA at GB20 can significantly improve facial and hindpaw mechanical withdrawal threshold of migraine rats, and its possible mechanism may be related to inhibiting microglia activation mediated by P2X7R in the PAG.
目的：观察电针“风池”对反复发作性偏头痛大鼠行为学、中脑导水管周围灰质(PAG)小胶质细胞激活及嘌呤能离子通道型受体7(P2X7R)表达的影响，探讨电针抗偏头痛中枢敏化的可能机制。方法：SD大鼠随机分为对照组、模型组、电针组，每组12只。反复硬脑膜电刺激诱导反复发作性偏头痛大鼠模型。电针组电针“风池”，每次10 min，每日1次，连续治疗9 d。电子von-Frey测痛仪检测各组大鼠第0、2、4、6、8天面部及后足底机械痛阈；免疫荧光染色法检测各组大鼠PAG区离子钙接头蛋白(Iba）-1阳性细胞数，Western blot 法检测各组大鼠PAG区Iba-1、白细胞介素(IL)-1β及 P2X7R的蛋白表达水平。结果：与对照组相比，模型组大鼠第2、4、6、8天面部及后足底机械痛阈均显著降低(P<0.01，P<0.001)；与模型组相比，电针组大鼠第4、6、8天面部及后足底机械痛阈显著升高(P<0.05，P<0.001，P<0.01)。与对照组相比，模型组大鼠PAG区小胶质细胞显著激活，Iba-1阳性细胞数明显增多(P<0.001)，Iba-1、IL-1β及P2X7R蛋白表达水平均显著升高(P<0.05)；与模型组相比，电针组大鼠PAG区Iba-1阳性细胞数减少(P<0.05)，Iba-1、IL-1β及P2X7R蛋白表达水平均显著降低(P<0.05)。结论：电针“风池”能显著改善偏头痛大鼠皮肤异常性疼痛，其可能与抑制PAG区P2X7R介导的小胶质细胞激活相关。.
Keywords: Electroacupuncture; Microglia; Migraine; P2X7 receptor.