Electroacupuncture exerts an anti-migraine effect via modulation of the 5-HT7 receptor in the conscious rat

Abstract

Background: Acupuncture has been recommended as an alternative therapy for migraine. Emerging evidence suggests that the 5-HT7 receptor (5-HT7R) plays a significant facilitatory role in descending modulation in migraine pathophysiology, and that activation of 5-HT7R in the descending pathway is involved in migraine central sensitisation. Objective: To investigate the ability of electroacupuncture (EA) to ameliorate central sensitisation via modulation of 5-HT7R in the descending pain pathways using a rat model of migraine induced by repetitive dural electrical stimulation (DES). Design: 64 male Sprague-Dawley rats were randomly divided into four groups: Normal group; DES group (receiving dural electrical stimulation only); DES+GB20 group (DES model group treated with EA at GB20); and DES+Sham group (DES model group treated with EA at a non-traditional (sham) acupuncture point). The presence of cutaneous allodynia was determined by measuring facial and hind-paw withdrawal latencies to electronic von-Frey. The expression of 5-HT7R in the descending pathways (periaqueductal grey, raphe magnus nucleus, and trigeminal nucleus caudalis) was assessed using immunofluorescence and Western blotting. Results: Facial and hind-paw withdrawal thresholds were significantly increased in the DES+GB20 group compared with the untreated DES group. The expression of 5-HT7R was significantly decreased in the DES+GB20 group compared with the DES group (one-way analysis of variance (ANOVA), P<0.05). No significant differences in behaviour or expression were found between the rats in the DES+Sham group and the untreated DES group (one-way ANOVA, P>0.05). Conclusion: EA at GB20 may ameliorate central sensitisation in migraine by inhibiting the activation of 5-HT7 receptors in the descending pain pathway in a rat model of migraine.