神经肽Y2受体在大鼠神经病理性痛中的作用

Role of neuropeptide Y2 receptor in neuropathic pain in rats

目的探讨神经肽Y2受体（NPY2R）在大鼠神经病理性痛中的作用。方法SPF级雄性sD大鼠36只，8周龄，体重190～210g，采用随机数字表法，将其分为3组（n=12）：假手术组（s组）、神经病理性痛组（NP组）和NPY2R反义寡核苷酸组（ODN组）。NP组和ODN组采用坐骨神经慢性压迫法制备神经病理性痛模型。术后7d时ODN组鞘内注射5μg／μl NPY2R反义寡聚核苷酸30μl。分别于术前3d（T0，基础状态）、术后7d（T1）、鞘内给药后15min、1．5、3．0、4．5、6．0h（T2-6）时测定机械痛阈和冷痛阈，然后处死大鼠，取L4-6脊髓组织，采用免疫荧光法测定脊髓背角神经元NPY2R、降钙素基因相关肽（CGRP）的表达和二者共表达（NPY2R／CGRP）水平。结果与s组比较，NP组和ODN组T4-6时机械痛阈降低，冷痛阈升高，脊髓背角神经元NPY2R、CGRP表达上调（P〈0．05）；与NP组比较，ODN组T3-5时机械痛阈升高，脊髓背角神经元NPY2R和NPY2R／CGRP表达下调（P〈0．05），冷痛敏和脊髓背角神经元CGRP表达差异无统计学意义（P〉0．05）。结论脊髓背角神经元NPY2R参与了大鼠神经病理性痛的机械痛觉过敏维持，而未参与冷痛觉过敏维持。

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 oligonucleotide group （group ODN）. NP was induced by chronic constrictive injury （CCI）. 5 μg/μl NPY2R antisense oligonucleotide 30μl was injected intrathecally 7 days after CCI in group ODN. While normal saline 30μl was injected intrathecally in group S. The mechanical paw withdrawal threshold and cold allodynia were measured 3 days before CCI （To, baseline）, 7 days after CCI （TI） and at 15 rain, 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 withdrawal 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.