Role of NF-κB signaling pathway in spinal cord in persisrtent postoperative pain in rats

Objective To investigate the role of NF-κB signaling pathway in the spinal cord in persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) in rats.Methods Ninety male SD rats weighing 200-250 g in which intrathecal (IT) catheter was successfully implanted without complication were randomly divided into 3 groups ( n =30 each):group sham operation ( group S ) ; groups SMIR and group pyrrolidine dithiocarbarnate (a NF-κB inhibitor) (group PDTC).Persistent postoperative pain was evoked by SMIR according to the method described by Flatters in groups SMIR and PDTC.PDTC 10 ng in 10 μl was injected IT over 30 s once a day for 7 consecutive days after operation in group PDTC.Mechanical paw withdrawal threshold to von Frey filament stimulation (MWT) was measured at 1 d before (T0,baseline) and 1,3,7,12 and 22 d after surgery (T1-5).Five animals in each group were sacrificed at each time point after MWT measurement and their lumbar segments of the spinal cord were removed for determination of TNF-α content (by ELISA).Results SMIR significantly decreased MWT after operation at T1-5 and increased TNF-α content in the spinal cord at T3-5.PDTC significantly attenuated SMIR-induced hyperalgesia and increase in TNF-α content in the spinal cord.Conclusion NF-κB signaling pathway in the spinal cord plays an important role in the development of SMIR-induced persistent postoperafive pain in rats. Key words: NF-kappa B;  Spinal cord;  Pain,postoperative