亚硝基铁氰化钠对脊髓背角神经元诱发与自发反应的影响

Effect of sodium nitroprusside on the spontaneous and induced responses of rat spinal cord dorsal horn neurons

用微透析方法在麻醉麻痹大鼠的脊髓局部应用一氧化氮 (NO)供体亚硝基铁氰化钠 (sodiumnitroprusside,SNP) ,以碳丝微电极在腰膨大处行细胞外记录 ,观察NO对机械刺激大鼠后足部皮肤引起的诱发反应和自发反应的影响。脊髓深层神经元透析 1μmol/LSNP ,10～ 2 0min后 ,非伤害性机械刺激诱发的反应增强 ,伤害性机械刺激诱发的反应减弱 ;透析 2 0～ 30min后 ,伤害性和非伤害性机械刺激诱发的反应均减弱 ;透析 2 0 μmol/LSNP 7～ 15min内伤害性和非伤害性机械刺激诱发的反应均降低。1μmol/L和 2 0 μmol/L的SNP均在一定时间内使自发放电增强。结果提示 :不同浓度的NO对脊髓非伤害性和伤害性信息传递具有不同的作用 ;

The present study was performed on anesthetized and paralyzed Wistar rats. Extracellular recordings were made from the lumbar enlargement of the spinal cord using carbon filament electrodes. NO donor sodium nitroprusside (SNP) was locally microdialyzed to the spinal cord, and effects of NO on spontaneous response and the responses induced by mechanical stimulation of the hind foot were observed. After dialyzing for 10～20 min, SNP at a concentration of 1 μmol/L increased the induced responses to innocuous mechanical stimulation and decreased those to noxoius mechanical stimulation. The induced responses to both innocuous and noxious mechanical stimulations were all decreased after dialyzing the same dose of SNP for 20～30 min. The decrease was shown within 7～15 min dialysis when SNP was used at a concentration of 20 μmol/L. SNP at both concentrations of 1 and 20 μmol/L increased spontaneous spikes of the recorded spinal units. These effects were shown preferentially in deep units. The data suggest that in the deeper neurons of the spinal cord NO of different concentrations has different effects on transmission of nociceptive and nonnociceptive signals induced by mechanical stimulation, and No is involved in the antinociception in spinal neurons and facilitates their spontaneous activity.[WT5HZ]