大鼠尾壳核内注射μ或δ型阿片受体激动剂对操作式条件反射的影响

Influence of Intra-Caudate-Putamen Injection of μ- or δ-Opioid Recptor Agonists on Operant Conditioning Reflex in Rats

通过微计算机,训练大鼠建立巩固的操作式防御性条件反射。尾壳核(CPU)内埋置套管后,进行微量注射阿片受体激动剂和条件反射测验。吗啡、亮氨酸脑啡肽或DAGO分别注于CPU后30min或2h,均引起条件反应率(CR)显著下降或伴有潜伏期(L)延长。稍大剂量的DPDPE亦导致CR下降,L无明显变化。以上药物对动物自发活动无影响。结果提示,尾壳核内注射μ或δ型阿片受体激动剂都抑制已巩固的条件反射的再现。

Wistar rats were trained to establish operant defense conditioning until the rats reached the criterion of consolidation. After cannulae were implanted into Caudate-Putamen (CPU) , microinjection of opioid agonists and three sessions of conditioning tests were sequentially conducted.Morphine (2μg) , Leu-enkephalin (60ng) , DAGO (60ng, 120ng) , injected into CPU significantly lowered conditioning rate (CR)during the 30min and 2h test session. Latence (L) also prolonged in some cases. However, no change of CE and L could be delected with DPDPE (60ng, 120ng) intra-CPU injection except for a higher dose (400ng) , whcih did cause CR depression during the 2h test session. CR and L returned to the control level during the 24h session in all experiments. The injection of the agonists mentioned above did not affect locomotor activity.Results suggest that activation of μ-or δ-opioid receptor in CPU inhibits retrieval of a consolidated condi tioning.