蛛网膜下腔注射多巴胺对丘脑束旁核痛反应神经元放电的影响

THE EFFECTS OF DOPAMINE INJECTED INTO SUBARACHNOID SPACE OF THE RAT ON THE ELECTRICAL DISCHARGES OF NOCICEPTIVE NEURONS IN PARAFASCICULAR NUCLEUS OF THALAMUS

目的 :观察大鼠脊髓蛛网膜下腔注射多巴胺 (DA)对丘脑束旁核痛反应神经元放电的影响。方法 :实验用Wistar大鼠 30只 ,以电刺激坐骨神经作为伤害性刺激 ,用玻璃微电极引导痛反应神经元的放电。结果 :蛛网膜下腔注射DA可引起丘脑束旁核痛兴奋神经元 (PEN)诱发放电频率减少 ,潜伏期延长 ;痛抑制神经元 (PIN)放电抑制时程缩短 ,放电频率增加。上述效应可被腹腔内注射DA受体阻断剂氟哌啶所阻断。结论 :在脊髓水平注射DA可抑制丘脑束旁核PEN电活动 ,加强PIN电活动 ,具有明显的镇痛效应 ,其机制可能是由于DA作用于脊髓的DA受体抑制了伤害信息向脑的传递。

Objective: To observe the effects of dopamine (DA) injected into spinal subarachnoid space on the electrical discharges of nociceptive neurons in parafascicularis nucleus. Methods: The electrical stimulation of sciatic nerve was used as noxious stimulus.The electrical activity of nociceptive neuron were recorded by glass microelectrode in 30 Wistar rats. Results: DA decreased the discharge frequency and increased the latency of pain excitation neuron (PEN), but shortened the duration and increased the discharge frequncy of pain inhibition neurons (PIN ). This effects could be blocked by DA antagonist droperidol. Conclusion:The spinal administration of DA inhibited the activity of PEN and enhanced the activity of PIN in parafascicularis nucleus induced by sciatic nerve stimulation. This suggests that DA inhibits pain transmission at the spinal cord level.