[Effects of electroacupuncture on ethology, microglia activation and P2X7 receptor expression in periaqueductal gray in rats with migraine].

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)-1ß 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-1ß 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.

Effect of Electroacupuncture at Fengchi on Facial Allodynia, Microglial Activation, and Microglia-Neuron Interaction in a Rat Model of Migraine.

The purpose of the work was to investigate whether electroacupuncture (EA) could ameliorate migraine central sensitization by modulating microglial activation and the subsequent release of inflammatory cytokines in the trigeminal nucleus caudalis (TNC) in a rat model. Establishment of a rat model of recurrent migraine was achieved through repeated dural electrical stimulation (DES). After nine sessions of acupuncture treatment at Fengchi (GB20), facial mechanical thresholds were measured by electronic von Frey measurements. Microglial activation and cytokine receptors of TNC were evaluated by immunofluorescence staining. The expression of microglial biological marker Ibal-1, proinflammatory cytokines, and cytokine receptors in the TNC were evaluated by Western blot and/or real-time polymerase chain reaction. In addition, the effects of inhibition of microglial activation on facial thresholds and neuronal activation (i.e., expression of c-Fos in the TNC) induced by DES were observed. After consecutive EA-GB20 treatments, the facial withdrawal threshold was significantly higher than in the model group at different time points (p < 0.05). The hyperreactivity of microglia induced by DES was significantly inhibited, and the expressions of Ibal-1, interleukin-1ß, tumor necrosis factor-α, and their receptors in the TNC were also significantly decreased (p < 0.05). Inhibition of microglia by minocycline demonstrated an acupuncture-like role, which was manifested by ameliorated mechanical hyperalgesia and decreased neuronal expression of c-Fos, Iba-1, and inflammatory factors. EA at GB20 could ameliorate migraine facial allodynia by inhibiting microglial activation and the subsequent release of inflammatory cytokines and their receptors in the TNC.