右旋美托咪啶对福尔马林炎性痛大鼠吗啡耐受的调节及机制

摘要

Objective To observe the effects of Dex on formalin inflammatory pain and morphine tolerance in rats and its mechanism.Methods Selected forty male SD rats,using 5% formalin to establish acute inflammatory pain model,were randomly di-vided into 4 groups,10 rats in each group.Group I (blank group),morphine tolerance group (morphine tolerance group),group III (group Dex),group IV (group Dex +NMDA).Expression of neuronal nitric oxide synthase (nNOS),messenger RNA (mRNA)and nitric oxide (NO)content and nitric oxide synthase (NOS)activity in spinal dorsal horn neurons were observed.Results The expres-sion of nNOS in spinal dorsal horn and mRNA in group I,group II,group III,IV group were,the group III of nNOS mRNA and the relative expression quantity and group I had no significant difference(P >0.05)but lower than that of group II and group IV(P <0.05);group III rats spinal cord dorsal horn of no content and NOS activity and group I no statistical significance(P >0.05),but com-pared with group II and IV group,no content were reduced 74.5% and 40%,NOS activity were decreased by 55.0% and 31.4%(P<0.05).Conclusion Among rats of the formalin inflammatory pain model,DEX can inhibit nNOS in spinal dorsal horn,mRNA ex-pression and NO production,so morphine tolerance has been reversed.%目的：观察右旋美托咪啶（Dex）对福尔马林炎性痛大鼠吗啡耐受的调节及机制。方法选取雄性 SD 大鼠40只，采用5％福尔马林建立急性炎性疼痛模型，随机分为4组，各10只。Ⅰ组（空白组）、Ⅱ组（吗啡耐受组）、Ⅲ组（Dex 组）、Ⅳ组（Dex ＋NMDA 组）。观察脊髓背角神经元型一氧化氮合酶（nNOS）、信使核糖核酸（mRNA）的表达及一氧化氮（NO）含量与一氧化氮合酶（NOS）活性。结果脊髓背角 nNOS 及 mRNA 在Ⅰ～Ⅳ组均有表达，组间脊髓背角 nNOS 及 mRNA 比较，差异具有统计学意义（P ＜0.01）；其中Ⅲ组 nNOS 及 mRNA 相对表达量与Ⅰ组无明显差异（P ＞0.05），但均低于Ⅱ、Ⅳ组（P ＜0.05）。组间脊髓背角 NO 含量及 NOS 活性比较，差异具有统计学意义（P ＜0.01）；其中Ⅲ组大鼠的脊髓背角 NO 含量和 NOS活性与Ⅰ组比较无明显差异（P ＞0.05），但均低于Ⅱ、Ⅳ组（P ＜0.05）。结论在福尔马林炎性痛大鼠模型中，Dex 可抑制脊髓背角 nNOS、mRNA 表达及 NO 产生，使吗啡耐受得到逆转。