Caffeine increases the motivation to obtain non-drug reinforcers in rats
Caffeine increases the motivation to obtain non-drug reinforcers in rats
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DOI：
10.1016/j.drugalcdep.2012.01.008
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发表时间：
2012-08-01
影响因子：
4.2
通讯作者：
Palmatier, Matthew I.
中科院分区：
文献类型：
--
作者：
Sheppard, A. Brianna;Gross, Skyler C.;Palmatier, Matthew I.
背景：咖啡因被广泛认为是人类的强化剂，但这种作用在非人类动物中很难测量。我们假设咖啡因可能具有与尼古丁相当的双重增强作用——有限的主要增强作用，但有效的增强增强作用。目前的研究通过调查咖啡因对非药物奖励反应的影响来检验这一假设。方法：在两项实验中，大鼠被塑造为对蔗糖溶液（20%，w/v；实验 1）的渐进比例（PR）方案或对适度增强的视觉刺激（VS；实验 2）的固定比例 2（FR2）方案做出反应。在连续工作日（周一至周五）进行测试之前，使用不同剂量的咖啡因（0-50 mg/kg，腹膜内注射）进行预处理。在实验 1 中，急性给予中低剂量咖啡因 (6.25-25 mg/kg) 可增加 PR 方案下对蔗糖的反应。在最初的 15 个测试天内，咖啡因的这种作用有所减弱。在实验 2 中，在 15 天的测试中，仅用 12.5 mg/kg 咖啡因进行急性预处理会增加对视觉刺激的反应，并且观察到对咖啡因这种效应的完全耐受。在后续测试中，我们发现4天和8天的戒断期导致咖啡因的增强作用恢复不完全。结论：研究结果表明咖啡因增强非药物刺激的增强作用，但这些作用的药理学特征可能与其他精神运动兴奋剂不同。 (C) 2012 Elsevier Ireland Ltd. 保留所有权利。
Background: Caffeine is widely considered to be a reinforcer in humans, but this effect is difficult to measure in non-human animals. We hypothesized that caffeine may have dual reinforcing effects comparable to nicotine - limited primary reinforcing effects, but potent reinforcement enhancing effects. The present studies tested this hypothesis by investigating the effect of caffeine on responding for non-drug rewards. Methods: In two experiments, rats were shaped to respond on a progressive ratio (PR) schedule for sucrose solution (20%, w/v; Experiment 1) or a fixed ratio 2 (FR2) schedule for a moderately reinforcing visual stimulus (VS; Experiment 2). Pretreatment with various doses of caffeine (0-50 mg/kg, intraperitoneal injection) were administered prior to tests over successive week days (M-F). In Experiment 1, acute administration of low-moderate caffeine doses (6.25-25 mg/kg) increased responding for sucrose under the PR schedule. This effect of caffeine declined over the initial 15 test days. In Experiment 2, only acute pretreatment with 12.5 mg/kg caffeine increased responding for the visual stimulus and complete tolerance to this effect of caffeine was observed over the 15 days of testing. In follow up tests we found that abstinence periods of 4 and 8 days resulted in incomplete recovery of the enhancing effects of caffeine. Conclusion: The findings suggest that caffeine enhances the reinforcing effects of non-drug stimuli, but that the pharmacological profile of these effects may differ from other psychomotor stimulants. (C) 2012 Elsevier Ireland Ltd. All rights reserved.