The Role Of P38MAPK Activation In The Rat Spinal Cord In Remifentanil-induced Postoperative Hyperalgesia

Objective To investigate the role of p38MAPK activation in spinal dorsal horn inremifentanil induced postoperative hyperalgesia. Methods Forty adult male SpragueDawley rats in which intrathecal catheters were implanted successfully, weighing230-270g,were randomly divided into5groups: control group (group Control), incision pain afteroperation group (group Incision), remifentanil group (group Remifentanil), p38MAPKinhibitor SB203580group (group SB203580) and dimethyl sulfoxide (group DMSO). NS10μL were given respectively intrathecally in group Control, group Incision and groupRemifentanil, while0.1%SB20358010μL and2%DMSO10μL were injected respectivelyintrathecally in group SB203580and group DMSO. In group Incision, the plantar incisionsurgery of the right hind paw was performed under1.5%isoflurane anesthesia, while in groupControl was not incised. The rest groups of rats were performed the same surgery with infusedremifentanil constantly. Radiant heat method and von Frey filaments were applied to testthermal paw withdrawal latency (PWL) and mechanical paw withdrawal threshold (PWT).Using immunohistochemistry method, p-p38MAPK positive cells in the spinal dorsal hornwere examined. Results Compared with group Incision, bilateral PWL and PWT weresignificant lower at4h,1d,2d and3d after incision in group Remifentanil and groupDMSO, the number of positive cells of p-p38MAPK in the bilateral spinal dorsal hornincreased significantly; Compared with group Remifentanil, bilateral PWT and ipsilateralPWL to the incision increased significantly in corresponding point of time post-incision ingroup SB203580, the number of positive cells of p-p38MAPK in the bilateral spinal dorsal horn decreased significantly. Conclusion The activation of p38MAPK in spinal dorsal hornmay be involved in remifentanil induced postoperative hyperalgesia．...