Kirshenbaum Ari, Green John, Fay Michael, Parks Angelique, Phillips Jesse, Stone Jason, Roy Tessa
Department of Psychology, Saint Michael's College, 1 Winooski Park Avenue, Colchester, VT, 05439-0001, USA,
Psychopharmacology (Berl). 2015 May;232(9):1583-94. doi: 10.1007/s00213-014-3792-y. Epub 2014 Nov 18.
Nicotine discontinuation produces behaviors in rats that are congruent with anhedonia, and these symptoms may be related to the devaluation of non-nicotine reinforcers.
Four separate experiments were performed to explore the parameters surrounding nicotine-induced reinforcer devaluation.
In Experiments 1 and 2, nicotine (0.1 or 0.3 mg/kg) or 0.3 mg/kg nicotine plus 1.0 mg/kg mecamylamine was delivered to rats prior to progressive ratio (PR) schedule sessions in which sucrose was used as a reinforcer. In order to evaluate (a) reinforcer enhancement by nicotine and (b) reinforcer devaluation in the absence of nicotine, all rats experienced two PR schedule sessions per day for 10 days. Experiment 3 involved nicotine (0.3 mg/kg) and a visual stimulus in place of sucrose reinforcement. In Experiment 4, rats received nicotine (0.3 mg/kg) either before or after a single PR schedule session for 10 days.
Experiments 1 and 2 demonstrate that reinforcer devaluation is related to the occupation of nicotinic-acetylcholine receptors. Results from Experiment 3 provide some evidence that devaluation occurs with either sucrose or visual-stimulus reinforcement. Experiment 4 demonstrates that a necessary condition for reinforcer devaluation to occur is the concurrent exposure to the reinforcer and nicotine.
Reinforcer devaluation in rats emerges rapidly in a progressive, orderly fashion that coincides with accumulated exposure to nicotine. These results suggest that reinforcer devaluation may be a feature of nicotine that contributes to the abuse liability of tobacco products.
尼古丁戒断会使大鼠产生与快感缺失相符的行为，这些症状可能与非尼古丁强化物的贬值有关。
进行了四项独立实验，以探究尼古丁诱导强化物贬值的相关参数。
在实验1和实验2中，在采用蔗糖作为强化物的累进比率（PR）程序实验环节之前，给大鼠注射尼古丁（0.1或0.3毫克/千克）或0.3毫克/千克尼古丁加1.0毫克/千克美加明。为了评估（a）尼古丁对强化物的增强作用以及（b）无尼古丁情况下强化物的贬值情况，所有大鼠每天进行两次PR程序实验，持续10天。实验3涉及用尼古丁（0.3毫克/千克）和视觉刺激替代蔗糖强化物。在实验4中，大鼠在进行为期10天的单次PR程序实验之前或之后接受尼古丁（0.3毫克/千克）注射。
实验1和实验2表明，强化物贬值与烟碱型乙酰胆碱受体的占据有关。实验3的结果提供了一些证据，表明无论是蔗糖还是视觉刺激强化物都会出现贬值情况。实验4表明，强化物贬值发生的一个必要条件是强化物与尼古丁同时存在。
大鼠的强化物贬值以渐进、有序的方式迅速出现，这与尼古丁的累积暴露情况相符。这些结果表明，强化物贬值可能是尼古丁的一个特征，它导致了烟草制品的滥用倾向。
