甲基丙烯酸甲酯对大鼠外周神经痛行为学影响的研究

The study on pain threshold effected by methylmethacrylate (MMA) in rat

目的观察SD大鼠足底皮下注射甲基丙烯酸甲酯单体(methylmethacrylate,MMA)后爪体积、自发痛和机械痛敏等指标变化,以及布比卡因和传导机械痛的P2X3受体选择性的抑制剂A-317491对疼痛的抑制、翻转效应.探讨MMA对外周神经痛行为学的影响.方法建立SD大鼠MMA疼痛模型.将不同浓度的MMA注射至大鼠足底皮下,在注射前和注射后不同时间点观察自发痛现象,并测定爪体积和机械痛敏的变化.用布比卡因和A-317491对MMA给药部位进行局部阻滞,以鉴别MMA对痛敏的影响是否是通过作用于外周神经发挥作用.结果①大鼠足底皮下注射2~50μL/ml浓度范围的MMA后引起机械痛敏明显下降.②200μL/ml浓度的MMA可引起注射侧足明显水肿、爪体积增大.500μL/ml以上浓度的MMA可诱发明显的持续1h的自发缩足反射、舔足等自发痛表现.③2μL/ml^50μL/ml浓度范围的MMA可诱发机械痛敏降低现象,而且也发生在对称的非注射侧部位.④0.2%布比卡因和A-317491能显著抑制和翻转MMA降低机械痛敏的作用.结论2μL/ml^50μL/ml浓度范围的MMA可诱发机械痛敏降低现象.MMA不会因提高椎体内感觉神经痛阈.

0bjective MMA-induced paw pain model in rat was explored to evaluate paw volume,spontaneous pain and mechanical threshold after subcutaneous injection of.MMA.Bupivacaine and A-317491 were applied to verify the peripheral mechanism was responsible for MMA-induced mechanical hyperalgesia.Met hods Subcutaneous injection of MMA was administered into the posterior plantar surface of the hind paw of rats.Paw volume,spontaneous pain and hind paw mechanical thresholds were measured before and after injection at gradient time-point.Bupivacaine and A-317491 were applied to block and reverse the mechanical hyperalgesia to verify if the effection was induced by peripheral nerve.Results①The mechanical threshold in the injection area was significantly down regulated after s.c.injection of 20μl L 2〜50μL/ml MMA.②200μL/ml MMA induced paw inflammatory edema.500μl L/ml MMA induced 1 h persistent spontaneous flinching reflex.③2μl L/ml^50 jjl L/ml MMA dose-dependently induced mechanical mirror-image pain.And mirror-image pain generated at the same segments of spinal cord as mechanical hyperalgesia.④Bupivacaine and A-317491 can block and reverse mechanical hyperalgesia induced by MMA at 1 h.Cone I us ions Mechanical hyperalgesia induced by 2μL/ml^50μL/ml MMA.MMA do not generate analgesia effect by up-regulate the mechanical pain threshold.