摘要
本文旨在研究阿片受体是否参与丘脑中央下核(nucleus submedius, Sm)和顶盖前区前核(anterior pretectal nucleus, APtN)所介导的不同强度电针的镇痛作用。以辐射热诱发甩尾(tail flick, TF)反射潜伏期为伤害性反应的指标, 观察了Sm 和APtN 微量注射阿片受体拮抗剂纳洛酮对不同强度电针“足三里”穴(St. 36)抑制大鼠TF反射的效应。结果表明, Sm 给予纳洛酮(1.0 μg, 0.5μl)阻断强电针(5 mA)对TF反射的抑制效应,而对弱电针(0.5 mA)的效应无明显影响; 相反, APtN 给予纳洛酮阻断弱电针对TF反射的抑制效应,而对强电针的效应无明显影响;纳洛酮供给到 Sm 或 APtN 邻近其它脑区对强、弱电针的效应均无影响。这些结果提示, Sm 内的阿片受体参与介导强电针兴奋细传入纤维(A-δ 和 C 类)产生的镇痛,而APtN 内的阿片受体则介导弱电针兴奋粗传入纤维(A-β 类)产生的镇痛。
Previous studies have indicated that the thalamic nucleus submedius (Sm) and the anterior pretectal nucleus (APtN) are involved in the descending modulation of nociception. The aim of the present study was to examine whether the opioid receptors in the Sm and APtN mediated the electroacupuncture (EA)-produced analgesia. The latency of tail flick (TF) reflex induced by radiant heat was used as an index of nociceptive response. The effects of microinjection of opioid receptor antagonist naloxone (1.0 μg, 0.5 μl) into Sm or APtN on the inhibition of the TF reflex induced by EA of “Zusanli” point (St. 36) with high- (5.0 mA) and low- (0.5 mA) intensity were examined in the lightly anesthetized rats. Sm microinjection of naloxone blocked the high- but not low-intensity EA- induced inhibition of the TF reflex. In contrast, naloxone applied to APtN blocked the low- but not high-intensity EA-induced inhibition. When naloxone applied to other brain regions adjacent to Sm or APtN, the EA-induced inhibition was not influenced under either high- or low-intensity condition. These results suggest that opioid receptors in Sm are involved in mediating the analgesia by high- intensity EA for exciting small (A-δ and C group) afferent fibers, while opioid receptors in APtN are involved in mediating the analgesia induced by low-intensity EA for only exciting large (A-β) afferent fibers.
出处
《生理学报》
CAS
CSCD
北大核心
2004年第6期697-702,共6页
Acta Physiologica Sinica
基金
This work was supported by the National Natural Science Foundation of China (No. 30270453).
关键词
阿片受体
纳洛酮
丘脑中央下核
顶盖前区前核
电针镇痛
甩尾反射
opioid receptor
naloxone
nucleus submedius
anterior pretectal nucleus
electroacupuncture analgesia
tail flick reflex
