Role of neuropeptide Y2 receptor in neuropathic pain in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of neuropeptide Y2 receptor (NPY2R) in neuropathic pain (NP) in rats.Methods Thirty-six adult male Sprague-Dawley rats,aged 8 weeks,weighing 190-210 g,were randomly divided into 3 groups (n =12 each):sham operation group (group S),group NP and NPY2R antisense ohgonucleotide group (group ODN).NP was induced by chronic constrictive injury (CCI).5 μg/μl NPY2R antisense oligonucleotide 30 μl was injected intrathecally 7 days after CCI in group ODN.While normal saline 30 μl was injected intrathecally in group S.The mechanical paw withdrawal threshold and cold allodynia were measured 3 days before CCI (T0,baseline),7 days after CCI (T1) and at 15 min,1.5,3.0,4.5 and 6.0 h after intrathecal injection (T2-6).The animals were then sacrificed after the last measurement and the lumbar segment of spinal cord was removed for determination of the expression of NPY2R and calcitonin gene-related peptide (CGRP) and co-expression of NPY2R with CGRP in spinal dorsal horn neurons (by immuno fluoresceence).Results Compared with group S,the mechanical paw withdrawal threshold was significantly decreased and cold allodynia was increased at T1-6,and the expression of NPY2R and CGRP and co-expression of NPY2R with CGRP in spinal dorsal horn neurons was up-regulated in NP and ODN groups (P ＜ 0.05).Compared with group NP,the mechanical paw with-drawal threshold was significantly increased at T3-5,and the expression of NPY2R and co-expression of NPY2R with CGRP in spinal dorsal horn neurons was down-regulated (P ＜ 0.05),and no significant change was found in cold allodynia and the expression of CGRP in spinal dorsal horn neurons in ODN group (P ＞ 0.05).Conclusion NPY2R in the spinal cord dorsal horn is involved in the maintenance of mechanical hyperalgesia,but not in the maintenance of clod hyperalgesia in rats.