Delius Juan D, Acerbo Martin J, Krug Ines, Lee Jennifer, Leydel Rita
Allgemeine Psychologie, University of Konstanz, Konstanz, Germany.
Behav Pharmacol. 2015 Feb;26(1-2):139-58. doi: 10.1097/FBP.0000000000000087.
Apomorphine (apo), an unspecific direct dopamine agonist, elicits an intense and lasting pecking bout in pigeons. Apo yielded orderly dose-response functions, and repeated administrations led to sensitization. Strain and individual differences in sensitivity to apo were at least partly due to genetic factors. However, a strong cage-context dependency of the sensitization, which is indicative of conditioning, occurred in both pigeon strains studied. Apo-induced pecking and sensitization also occurred in total darkness. Pigeons could be conditioned to discriminate between an apo state and a non-apo state. A small dose of apo was effective as a conditioned stimulus when paired with a high dose as an unconditioned stimulus. The conditioned response (CR) was strongly specific to the context in which the sensitization to apo took place. The resistance to extinction of the CR could be increased through an oversensitization treatment. The incremental responses arising during the sensitization treatment and the CRs shown afterward by individual pigeons correlated significantly. The sensitization to apo in pigeons is well accounted for by a conditioning schema in which an interoceptive drug state is a conditional conditioned stimulus for the full expression of the incremental response. Variants of the scheme might also account for the sensitization of rodents to psychostimulants. A neural model that embodies the characteristics of the conditioning scheme has been proposed.
阿扑吗啡（apo）是一种非特异性直接多巴胺激动剂，可引发鸽子强烈且持久的啄击行为。阿扑吗啡呈现出有序的剂量反应函数，重复给药会导致敏化。对阿扑吗啡敏感性的品系和个体差异至少部分归因于遗传因素。然而，在研究的两种鸽子品系中，均出现了敏化对笼子环境的强烈依赖性，这表明存在条件作用。阿扑吗啡诱导的啄击和敏化在完全黑暗的环境中也会发生。鸽子能够被训练区分阿扑吗啡状态和非阿扑吗啡状态。当小剂量阿扑吗啡与高剂量阿扑吗啡作为无条件刺激配对时，小剂量阿扑吗啡作为条件刺激是有效的。条件反应（CR）对阿扑吗啡敏化发生的环境具有很强的特异性。通过过度敏化处理可以增强条件反应对消退的抵抗力。个体鸽子在敏化处理期间产生的增量反应与之后表现出的条件反应显著相关。鸽子对阿扑吗啡的敏化可以通过一种条件作用模式得到很好的解释，在这种模式中，内感受性药物状态是增量反应充分表达的条件性条件刺激。该模式的变体也可能解释啮齿动物对精神兴奋剂的敏化。已经提出了一个体现条件作用模式特征的神经模型。
