刺激游离的弓状核不再抑制丘脑束旁核神经元的伤害性反应

STIMULATION OF ISOLATED ARCUATE NUCLEUS NO LONGER EXHIBITS INHIBITION ON THE NOCICEPTIVE DISCHARGES OF THALAMIC PARAFASCICULAR NEURONS

以Ｈａｌａｓｚ刀游离大鼠下丘脑弓状核（ＡＲＣ）区，切断ＡＲＣ与其它脑区的神经通路而保持其与垂体的神经内分泌联系。用细胞外记录单位放电的方法观察了刺激这种游离的ＡＲＣ对丘脑束旁核（Ｐｆ）神经元伤害性反应的影响。结果：（１）Ｐｆ神经元对坐骨神经伤害性刺激呈现兴奋、抑制和先兴奋后抑制三种型式的反应；（２）刺激正常ＡＲＣ可抑制Ｐｆ神经元的伤害性反应；（３）刺激游离的ＡＲＣ不再出现对Ｐｆ神经元伤害性反应的抑制。研究结果提示：刺激ＡＲＣ之所以产生镇痛，通过β内啡肽能神经元抑制Ｐｆ神经元的伤害性反应可能是主要通路之一。

Rat hypothalamic arcuate nucleus (ARC) area was isolated with Halasz knife to interrupt the neural pathways of ARC with other brain areas, while its neuroendocrine connection with the pituitary remained intact. Effects of stimulation of the isolated ARC on nociceptive discharge of thalamic parafascicular (Pf) neurons were observed by extracellular recording technique. The results showed that:(1) there were three types of neurons responding to noxious sciatic stimulation: excitatory, inhibitory and biphasic; (2) stimulation of intact ARC was able to inhibit nociceptive responses of Pf neurons; (3) stimulation of isolated ARC no longer exhibited inhibitory effect on the nociceptive responses of Pf neurons. These results suggest that the inhibition of nociceptive responses of thalamic Pf neurons by the activation of β endorphinergic neurons during ARC stimulation might be the main analgesic pathway of ARC stimulation.