Role of poly (ADP-ribose) polymerase 1 in spinal cord in a rat model of neuropathic pain

Abstract

Objective To evaluate the role of poly (ADP-ribose) polymerase 1 (PARP1) in spinal cord in a rat model of neuropathic pain.Methods One hundred and eighty male Wistar rats weighing 180-220 g were randomly divided into 4 groups( n =45 each): sham operation group(group S),neuropathic pain group (group NP),siRNA negative control group (group NS) and PARP1-siRNA group (group PS).Neuropathic pain was produced by L5 spinal nerve ligation (SNL).Viral of PARP1-siRNA or viral of siRNA negative control was injected intrathecally after SNL in groups PS or NS.Mechanical pain threshold was determined at 3,7 and 14 d after SNL.Then the rats were sacrificed and L5 lumbar spinal tissues were removed for determination of coexpression of PARP1 with glial fibrillary acidic protein (GFAP) (by immunohistochemistry double stain),protein expression of PARP1 and GFAP (by Western blot),and mRNA expression of PARP1 and GFAP (by RT-PCR).Results Compared with group S,mechanical pain threshold was significantly decreased and the protein and mRNA expression of GFAP and PARP1 up-regulated in groups NP,NS and PS( P ＜ 0.05).Compared with groups NP and NS,mechanical pain threshold was significantly increased and the protein and mRNA expression of GFAP and PARP1 down-regulated in group PS (P ＜ 0.05).There was no significant difference in above indexes between groups NP and NS(P ＞0.05 ).PARR1 was expressed in the astrocytes in the spinal cord.Conclusion PARP1 is involved in the formation and maintainance of neuropathic pain in rats via activating astrocytes. Key words: ADP-ribose; Neuralgia; Spinal cord