侧脑室微量注射 NO 供体对大鼠痛行为反应的影响

The effect of administration of sodium nitroprusside into intracerebroventricle on the pain behavior of the rat

目的考察一氧化氮（ＮＯ）在前脑对大鼠痛行为的影响。方法采用辐射热作为伤害性刺激，以浅麻状态大鼠甩尾潜伏期（ＴＦＬ）为测痛指标，观察侧脑室和隔核分别微量注射硝普钠或亚甲基兰对痛阈的影响。结果侧脑室注射硝普钠使大鼠ＴＦＬ显著性减小（Ｐ＜０．０５），其最大值为３６．２％，持续时间为２０分钟；该作用可被ＮＯ的螯合剂血红蛋白阻断。隔核内注入硝普钠对ＴＦＬ的影响与上述结果相似。侧脑室注射亚甲基兰使大鼠ＴＦＬ显著性升高（Ｐ＜０．０５）。结论ＮＯ在大鼠前脑对痛行为反应具有易化作用；且部分是通过ＮＯ—ｃＧＭＰ通路实现的。

Objective To study the effect of nitric oxide (NO) in the forebrain on the pain behavior of the rat.Methods The tail flick latency (TFL) in lightly pentobarbital anesthetized rat by nociceptive stimulation with radiant heat was measured as the pain threshold.Effects of administration of sodium nitroprusside (SNP) and methylene blue respectively into intracerebroventricle (i.c.v) or septal nucleus on the pain behavior were investigated.Results Compared with control group,administration of SNP into i.c.v significantly produced a facilitation of the TFL(P<0 05),the maximal facilitation of the TFL was 36.2% and time of the facilitation about 20min.This effect of SNP was completely blocked by together with administration of the NO chelater hemoglobin.Administration of SNP into the septal nucleus caused the same effect on the TFL as above.Methylene blue,a soluble guanylate cyclase inhibitor,significantly produced antinociception by i.c.v administration (P<0 05). Conclusions These results suggest that NO in the forebrain produces a facilitation of the pain behavior of the rat and this facilitation is,at least,partially mediated via the NO-cyclic GMP pathway.