Connexin43 expression in trigeminocervical complex and its effect on allodynia in rats with migraine

Objective To investigate the efficacy of connexin43 (Cx43) in trigeminocervical complex on allodynia in rat models of migraine.Methods SD rats were randomly divided into 9 groups (n=6):blank group,sham-operated group,saline group,improved inflammatory soup for 3 d group,improved inflammatory soup for 7 d group,carbenoxolone (CBX) prevention group,CBX prevention control group,CBX treatment group and CBX treatment control group.Improved inflammatory soup was used to stimulate the dual matter adjacent to the superior sagittal sinus of rats repeatedly to induce migraine models in the later 7 groups.The pain threshold of periorbital skin was measured by Von-Frey hairs.On the 11th postoperative day,the spinal cord was removed for detection of Cx43 expression in the trigeminocervical complex by immunofluorescence.Results Von-Frey hairs study showed that:the pain threshold of improved inflammatory soup groups had a daily drop; rats in the improved inflammatory soup for 3 d group suffered allodynia,while those in the CBX prevention group did not; the pain threshold in the CBX treatment group ascended after using CBX.Immunofluorescence of nucleus and Cx43 showed that:the mean optical density (OD) of improved inflammatory soup for 3 d group and for 7 d group significantly incresed (P＜0.05); nucleus and Cx43 abundantly expressed in lamina Ⅰ and Ⅱ of dorsal horn in the improved inflammatory soup for 3 d group and lamina Ⅰ-Ⅳ of dorsal horn in improved inflammatory soup for 7 d group; significant difference was noted on the mean OD values between of CBX prevention/treatment groups and their control groups (P＜0.05).Conclusion Repeatedly infusing improved inflammatory soup to dual matter can effectively induce allodynia in rat models of migraine and Cx43 abundantly expresses in trigeminocervical complex after being given the soup; allodynia in migraine model of rats can be prevented and relieved by intraperitoneal administrating of CBX,which suggests that Cx43 may play an important role in allodynia of migraine. Key words: Migraine;  Allodynia;  Astrocytes;  Connexin43;  Carbenoxolone