Role of Cx43 hemichannel in spinal cord dorsal horn in rat acute incision pain / 中国药理学通报

ABSTRACT

Aim To study the role of Cx43 hemichannel in rats with acute incision pain. Methods Adult male rats were randomly divided into normal saline group(C group), incision pain group(I group), Gap19 group. Western blot was used to determine the expression of Cx43 and GFAP at 6 h, 3 d and 7 d after paw incision surgery of rats. The rats were intrathecal injected with Gap19 30 min before incision surgery, followed by the measurement of the paw withdrawal threshold to mechanical stimuli at several time points. Immunofluorescence was used to detect the expression of Cx43 and GFAP. ELISA was performed to detect the different inflammatory cytokine levels in rats after surgery. Results Compared with group C, the expression of Cx43 and GFAP of rats increased significantly 6 h after incision surgery in group I, while their expression at postoperative 3 d and 7 d showed no obvious alteration. Compared with the preoperative baseline, the mechanical paw withdrawal threshold in I group and Gap19 group rats was significantly reduced at 2 h, 6 h, 24 h and 3 d post-incision(P<0.01), but it had no obvious change on postoperative 7 d. Compared with group I, the mechanical paw withdrawal threshold in rats of Gap19 group increased 2 h, 6 h, 24 h post-incision, while it showed no statistical difference on 3 d and 7 d post-incision. Compared with group C, immunofluorescence results showed that the expression of GFAP and Cx43 in spinal cord dorsal horn astrocytes also increased significantly in Group I 6 h after incision surgery. Compared with group I, GFAP and the expression of Cx43 were markedly reduced in Gap19 group. There was no statistical difference on 7 d post-incision. Compared with those in group C, the inflammation factors including IL-1β, IL-6 and TNF-αobviously increased in group I. However, in contrary to the rats in group I, the rats pretreated with gap19 showed increased expression of Cx43 and GFAP in spinal cord dorsal horn. Conclusions Specific inhibition of Cx43 hemichannel significantly suppresses astrocyte activation and alters the inflammatory microenvironment in the spinal cord dorsal horn and reduces postoperative hyperalgesia in rats with acute incision pain.