Twining Robert C, Bolan Matthew, Grigson Patricia S
Department of Neural and Behavioral Sciences, Pennsylvania State College of Medicine, Hershey, USA.
Behav Neurosci. 2009 Aug;123(4):913-25. doi: 10.1037/a0016498.
In Experiment 1, water-deprived rats had 5-min access to saccharin followed by active or yoked intravenous delivery of saline or cocaine (0.33 mg/infusion). Both cocaine groups avoided intake of the saccharin cue following saccharin-cocaine pairings; however, the rats in the yoked condition exhibited greater avoidance of the taste cue than did the actively administering rats. Experiment 2 evaluated subsequent self-administration behavior on fixed- and progressive-ratio schedules of reinforcement. The results showed that prior yoked exposure to cocaine reduced subsequent drug-taking behavior on a progressive-ratio but not on a fixed-ratio schedule. Finally, Experiment 3 used a choice test to determine the impact of yoked drug delivery on the relative preference for cocaine versus water. The results showed that rats with a history of self-administering cocaine preferred to perform operant behaviors on the side of the chamber previously paired with cocaine, whereas the rats with a history of yoked delivery of cocaine avoided this side. These data show that, in most rats, the unpredictable, uncontrollable delivery of cocaine protects against the subsequent motivation for cocaine through an aversive mechanism.
在实验1中，禁水的大鼠有5分钟时间接触糖精，随后通过主动或配对静脉注射生理盐水或可卡因（0.33毫克/次注射）。在糖精与可卡因配对后，两个可卡因组都避免摄入糖精线索；然而，配对条件下的大鼠比主动给药的大鼠对味觉线索表现出更大的回避。实验2评估了随后在固定比率和累进比率强化程序下的自我给药行为。结果表明，先前配对接触可卡因会降低随后在累进比率而非固定比率程序下的药物摄取行为。最后，实验3使用选择测试来确定配对药物注射对可卡因与水相对偏好的影响。结果表明，有自我给药可卡因历史的大鼠更喜欢在实验箱中先前与可卡因配对的一侧进行操作性行为，而有配对注射可卡因历史的大鼠则避开这一侧。这些数据表明，在大多数大鼠中，不可预测、无法控制的可卡因注射通过厌恶机制防止随后对可卡因产生动机。
