纳络酮对褪黑素抑制猫丘脑后核群诱发放电的影响

目的研究阿片受体阻断剂纳络酮对褪黑素 (melatonin ,MT)中枢镇痛作用的影响 ,进一步探索MT的作用机制。方法采用猫脑立体定位技术和玻璃微电极细胞外记录法 ,以刺激内脏大神经(GSN)诱发猫丘脑后核群 (PO)单位放电为内脏痛指标 ,侧脑室给药 ,观察药效。结果侧脑室注射(icv) 4 3 0× 1 0 -3 mol·L-1MT 1 0 μg·kg-1可明显抑制刺激GSN在PO诱发的单位放电 ,2 75×1 0 -3 mol·L-1纳络酮 (5 0 μg,icv)可部分拮抗MT对PO诱发放电的抑制作用。结论MT有中枢镇痛作用 ,MT的镇痛作用与增加内源性阿片系统的活动有关

Effect of naloxone on the inhibition of melatonin to the unit discharges evoked in the posterior group of thalamic nuclei in cats

Objective To study the effect of naloxone,an opioid recepter antagonist,on the central analgesic action of melatonin(MT) and to explore the mechanism of MT analgesia.Methods As an indicator of visceral pain,the unit discharges of the neurons in the posterior group of thalamic nuclei (PO) were caused by stimulating the great splanchnic nerve (GSN) of the cat.The cranial stereotaxic and extracellular glass microelectrode record technique was used.The drugs were given through the intra-cranial-ventricle(icv). Results 4.30×10 -3 mol·L -1 MT ( 10 μg·kg -1,icv)was shown to inhibit the unit discharge of the neurons in PO of the cat,which was evoked by stimulating GSN.The inhibition of 4.30×10 -3 mol·L -1 MT ( 10 μg·kg -1,icv)on the unit discharge of neurons in PO was partially antagonized by 2.75×10 -3 mol·L -1 naloxone( 50 μg,icv).Conclusions MT exhibited central anagesic action, which connected with the enhancement of the action of the endogenous opioid peptidergic system.