大鼠侧脑室微量注射硝普钠和亚甲基蓝对痛觉调制作用的影响

The effect of sodium nitroprusside and methylene blue on pain of modulation in central nervous system of rats

目的 观察侧脑室微量注射硝普钠和亚甲基蓝对大鼠痛阈的影响 ,分析和探讨中枢神经系统内一氧化氮 (NO)在大鼠痛觉调制中的作用和作用机理。方法 本实验以钾离子透入引起大鼠甩尾的电流强度 (m A )作为痛反应指标 ,研究大鼠侧脑室内微量注射硝普钠 (SNP)、亚甲基蓝 (MB)、血红蛋白 (Hb)等 ,对大鼠痛阈的影响。结果 侧脑室微量注射 NO前体L - Arg及供体物质 SNP均引起明显的痛敏效应。而注射 SNP和 Hb混合液大鼠痛阈无显著性改变。微量注射 L - NAME和MB后大鼠痛阈升高非常显著。侧脑室微量注射 MB和 L - Arg混合液后 ,大鼠痛阈较单纯注射 MB组表现出明显降低的趋势 ,但和 L - Arg组相比大鼠痛阈升高明显。结论 (1)提高中枢神经系统内 NO水平具有明显的痛敏效应 ,而降低中枢神经系统NO水平表现出显著镇痛作用。 (2 )中枢神经系统 NO对大鼠痛觉的调制作用至少一部分是通过 NO- c

Objective To Study the effect of nitric oxide(NO) on pain modulation in central nervous system of rats. Methods The potassium inotophoresis induced tail flick was used to measure the pain threshold(PT) of rats. The changes of pain threshold was investigated by microinjecting sodium nitroprusside(SNP), L arginine (L Arg), NG nitro L arginine methyl ester(L NAME), methylene blue(MB) and hemoglobin(Hb) into cerebral ventricular of rats. Results A significant hyperalgesia effects were observed by injecting SNP and L Arg into cerebral ventricular of rats, while the pain threshold was no changes by injecting the mixed liquid which was included SNP and Hb. The pain threshold of rats were increased significantly by microinjecting L NAME and MB into ventricular of brain. When the MB plus L Arg mixed liquid (MB L Arg group) was injected into cerebral ventricular of rats, the pain threshold of rats was decreased compared with that of MB group,but it was riser than that of L Arg group remarkably. Conclusion These results suggested that an increase of NO in brain produce hyperalgesia, and a decrease of NO level produce analgesia. The effects of nitric oxide on modulation of pain in central nervous system of rats may be partly mediated by NO cyclic GMP pathway.