ObjectiveTo study the effects of intrathecal injection of CaMK Ⅱ inhibitor KN93 on the hyperalgesia induced by remifentanil in a incision pain model.MethodsSixty SD rats were divided randomly into 5 groups ( n =12):C group (control) ; (I) group ( incision pain ) ; R group ( incision pain + remifentanil ) ; DMSO group ( incision pain + remifentanil + DMSO) and KN93 group ( incision pain + remifentanil).In group R,DMSO and KN93,remifentanil (0.04 mg/kg,1 mg remifentanil was dissolved in 40 ml NS ) needed to be infused subcutaneously 30 min at the moment of surgery.Group DMSO and group KN93 were respectively intrathecal injected 20 μl DMSO( 10％ ) and 20 μl KN93 (50 μg/20 μl,dissolved in 10％ DMSO).Each rat received tests of the paw mechanical withdrawal threshold (PMWT) and the paw withdrawal thermal latency (PWTL) at the times of 24 h before and 2h,6h,24h,48h after surgery.ResultsCompared with the group C,the PWTL( ( 11.24 ± 0.69) s,(10.36 ±0.29)s,(11.29 ±1.12)s,(12.21 ±0.75)s) and PMWT( (25.5 ± 1.20)s,(24.92 ± 1.98)s,(25.47± 1.54 ) s,( 27.14 ± 1.04 ) s) of the group I were significantly decreased after surgery (P ＜ 0.05 ).Compared with the group Ⅰ,the PWTL( (8.48 ±0.72)s,(8.58 ±0.45)s,(8.46 ±0.92)s,(9.07±0.79) s and PMWT( (21.2± 2.42 ) s,( 19.58 ± 1.12 ) s,( 21.87 ± 1.56 ) s,( 22.26 ± 1.64 ) s ) of the group R were significantly decreased after surgery (P ＜ 0.05 ).Compared with the group R,the PWTL( ( 13.32 ± 0.73 ) s,( 11.79 ± 0.32) s,( 11.86 ±0.98)s,(12.76 ±0.82)s) and PMWT((29.75 ±1.38)s,(28.27± 1.16)s,(26.5 ± 1.02)s,(27.79 ± 1.22)s) of the group KN93 were significantly increased (P ＜ 0.05 ).ConclusionIntrathecal injection KN93 could relieve the hyperalgesia induced by remifentanil

Objective To evaluate the role of transient receptor potential ion channel 1 (TRPA1) in the spinal dorsal horn neurons in maintenance of neuropathic pain in rats.Methods Fifty-six adult male SpragueDawley rats,weighing 200-250 g,were randomly divided into 4 groups (n =14 each):sham operation group (group S); chronic compression of dorsal root ganglia (CCD) group; CCD + dimethyl sulfoxide group (group D); and CCD + TRPA1 blocker HC-030031 group (group H).CCD was produced by infiltrating the L5 intervertebral foramen with 50 μl of a hemostatic matrix (SURGIFLO) in anesthetized rats in CCD,D and H groups.In D and H groups,10％ dimethyl sulfoxide 20 μl and HC-030031 50 μg were injected intrathecally at 7 days after CCD operation,respectively.Paw withdrawal threshold to mechanical stimulation (PWMT) was measured at 1 day before operation (T0),at 1 h before intrathecal administration (T1),and at 1,2,4,6,8,and 24 h after intrathecal administration (T2-7).Six rats in each group were sacrificed at T4 and T7,the L3-5 segments of the spinal cord were obtained for determination of TRPA1 expression in the spinal cord by Western blot.Results Compared with group S,PWMT was significantly decreased at T1-7,the expression of TRPA1 in the spinal cord was up-regulated at T4 and T7 in CCD and D groups,and the PWMT was decreased at T1 and T5-7 and the expression of TRPA1 was up-regulated at T7 in H group (P ＜ 0.05).Compared with CCD group,the PWMT was significantly increased at T2-5 and the expression of TRPA1 was down-regulated at T4 in H group (P ＜ 0.05).Conclusion TRPA1 in the spinal dorsal horn neurons is involved in the maintenance of neuropathic pain in rats.