ABSTRACT
Objective To evaluate the role of membrane-bound complement regulatory protein expression in spinal cord dorsal horn in the development of neuropathic pain (NP) in rats.Methods Forty-eight male Sprague-Dawley rats,weighing 200-250 g,in which intrathecal catheters were successfully implanted without complications,were randomly divided into 4 groups (n =12 each):sham operation group (group S),group NP,normal saline group (group NS) and minocycline group (group M).NP was induced by chronic constrictive injury of the sciatic nerve in NP,NS and M groups.Minocycline 50 μg was injected intrathecally once a day for 7 consecutive days starting from 1 day before ligation of the sciatic nerve in M group,while the equal volume of normal saline was given in stead of minocycline in NS group.Mechanical pain threshold and thermal pain threshold were measured at 1 day before ligation of the sciatic nerve (baseline,T0) and 1,3,7 days after ligation of the sciatic nerve (T1-3).Then the rats were sacrificed at T3 and the lumbar segment (L4,5) of spinal cord was removed for determination of the expression of CD46,CD55,CD59 protein and mRNA in the dorsal horn of spinal cord by Western-blot and RT-PCR,respectively.Results Compared with S group,mechanical pain threshold and thermal pain threshold were significantly decreased at T1-3 and the expression of CD46,CD55 and CD59 protein and RNA was down-regulated at T3 in NP,NS and M groups (P ＜ 0.05).Compared with groups NS and NP,mechanical pain threshold and thermal pain threshold were significantly increased at T2.3 and the expression of CD46,CD55 and CD59 protein and RNA was up-regulated at T3 in M group (P ＜ 0.05).Conclusion The down-regulated expression of membrane-bound complement regulatory proteins in spinal cord dorsal horn and abnormal activation of the complement are involved in the development of NP in rats.