Role of transient receptor potential ion channel 1 in spinal dorsal horn neurons in maintenance of neuropathic pain in rats

Abstract

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. Key words: Transient receptor potential channels; Posterior horn cells ; Neuralgia