刺激大脑皮层体感Ⅰ区和大脑脚对大鼠脊髓背角神经元伤害感受性反应的影响

在大鼠用玻璃微电极细胞外记录的方法,观察了刺激皮层体感Ⅰ区(SI区)和大脑脚(CP)对皮肤强电刺激诱发的脊髓背角广动力范围(WDR)神经元长潜伏期反应(C-反应)的影响。结果表明刺激SI区对背角WDR神经元C-反应的影响以抑制为主,刺激CP的作用与刺激SI区的作用相似,但刺激CP更为有效。抑制作用的持续时间在不同神经元差别很大,短者在刺激停止后仅持续400ms,长者可达10min以上。静注纳洛酮对抑制作用无明显影响,静注二甲麦角新碱在部分神经元可使抑制作用明显减弱或完全消失,提示5-HT部分参与皮层下行抑制作用的实现,而内鸦片肽则否。

EFFECTS OF STIMULATION OF SI CORTEX AND CEREBRAL PEDUNCLE ON THE NOCICEPTIVE RESPONSES OF SPINAL DORSAL HORN NEURONS IN THE RAT

Single spinal dorsal horn neurons were recorded extracellularly with glass mi-cropipettes, and the effect of stimulation Of SI cortex or cerebral peduncle (CP) wasobserved on the long latency discharges (C--fiber evoked response) of the wide dynam-ic range (WDR) neurons induced by intense electrical skin stimulation. Inhibitionwas the predominant effect of SI cortex stimulation on the C--fiber evoked responses ofWDR neurons. The effect of CP stimulation was similar to that of SI cortex stimula-tion, except that the former was much more effective than the latter. The inhibitionlasted a period of time varying from 400 ms to more than 10 min after CP stimula-tion in different neurons. Systemic naloxone had no significant effect on the inhibi-tion produced by CP stimulation. Systemic methysergide reduced or eliminated the in-hibition in a part of the neurons tested, suggesting that 5--HT, but not opioid Peptides,is involved partially in mediation of the descending inhibitory effect originating fromthe cortex.