Massey B.W., McMillan D.E., Wessinger W.D.
Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
Behav Pharmacol. 1992 Oct;3(5):475-488.
The stimulus control by morphine under a fixed-interval (FI) 180-s schedule of reinforcement was examined in five pigeons trained to discriminate 5.0mg/kg of i.m. morphine from saline. After training, dose-response relationships were determined for morphine, d-amphetamine, pentobarbital, fentanyl, and MK-801. At low doses of morphine, responding of individual subjects was predominantly on the saline-appropriate key. At intermediate doses responding occurred on both keys throughout the interval. Following doses of 5.6mg/kg and higher, responding on both keys was observed in the early portions of the interval with responding shifting to the morphine-appropriate key as the interval progressed. Thus, a graded dose-effect curve for morphine was obtained under the FI schedule. The fentanyl dose-effect curve was similar to that obtained with morphine, but the other test drugs were not generalized. Five other pigeons were trained to discriminate 5.0mg/kg of morphine from saline under a fixed-ratio (FR) 100 schedule of reinforcement. During testing with morphine, responses were confined to the saline-appropriate key at 0.3 and 1.0mg/kg of morphine, but at higher doses responses were confined to the drug key. In contrast to the results obtained using the FI schedule, a quantal relationship for responding on the two keys was observed when a FR schedule was employed.
在五只因辨别5.0毫克/千克肌肉注射吗啡与生理盐水而接受训练的鸽子中，研究了在固定间隔（FI）180秒强化程序下吗啡的刺激控制作用。训练后，测定了吗啡、右旋苯丙胺、戊巴比妥、芬太尼和MK-801的剂量-反应关系。在低剂量吗啡时，个体受试者的反应主要在与生理盐水匹配的按键上。在中等剂量时，整个间隔期间两个按键上都有反应。在5.6毫克/千克及更高剂量后，在间隔的早期阶段观察到两个按键上都有反应，随着间隔的进行，反应转移到与吗啡匹配的按键上。因此，在FI程序下获得了吗啡的分级剂量-效应曲线。芬太尼的剂量-效应曲线与吗啡相似，但其他受试药物没有产生泛化。另外五只鸽子在固定比率（FR）100强化程序下接受训练以辨别5.0毫克/千克吗啡与生理盐水。在用吗啡测试期间，在0.3和 1.0毫克/千克吗啡时反应局限于与生理盐水匹配的按键，但在更高剂量时反应局限于药物按键。与使用FI程序获得的结果相反，当采用FR程序时，观察到在两个按键上反应的量反应关系。
