The effect of novelty on amphetamine self-administration in rats classified as high and low responders
The effect of novelty on amphetamine self-administration in rats classified as high and low responders
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DOI：
10.1007/s00213-004-1870-2
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发表时间：
2004-11-01
影响因子：
3.4
通讯作者：
Bardo, MT
中科院分区：
文献类型：
--
作者：
Cain, ME;Smith, CM;Bardo, MT
理由：根据在不可避免的新环境中的活动，将大鼠归类为高反应者 (HR)，与低反应者 (LR) 大鼠相比，它们会自行施用更多的安非他明。先前的研究还表明，在安非他明自我给药过程中出现的新刺激会减少输注次数。目的：本研究确定了对不可避免的或自由选择的新奇事物的个体差异是否可以差异预测新奇刺激减少安非他明自我给药的能力。此外，这项研究还确定了新的刺激是否能够通过重复呈现来保持减少自我给药的能力，以及新的刺激的效果是否随着所测试的安非他明单位剂量的函数而变化。方法：筛选雄性大鼠在不可避免的、自由选择的新奇测试中的反应。使用高单位剂量的安非他明（每次输注 0.1 毫克/千克）进行初始训练后，剂量减少（每次输注 0.03 毫克/千克），并在四个单独的训练室中在操作调节室中呈现新的刺激。在实验 2 中，在多个疗程中以不同的安非他明剂量（每次输注 0.003、0.01、0.03 和 0.056 mg/kg）呈现新的刺激。结果：四次新刺激的重复出现减少了安非他明的自我给药，而重复出现后新刺激的效果没有显着损失。在实验2中，新的刺激减少了低单位剂量（每次输注0.003 mg/kg和0.01 mg/kg）的安非他明自我给药，并且根据其在不可避免的新刺激中的活动被分类为HR的大鼠比LR大鼠更容易受到新刺激的干扰。结论：这些结果表明，重复出现新刺激可以减少低单位剂量的安非他明自我给药，并且 HR 大鼠比 LR 大鼠对与安非他明竞争反应的非药物刺激更敏感。
Rationale: Rats categorized as high responders (HR) based on their activity in an inescapable novel environment self-administer more amphetamine than low responder (LR) rats. Previous research has also demonstrated that novel stimuli presented during the amphetamine self-administration session decreases the number of infusions earned. Objectives: This study determined whether individual differences in response to inescapable or free-choice novelty differentially predict the ability of novel stimuli to decrease amphetamine self-administration. Further, this study determined whether novel stimuli maintained the ability to reduce self-administration with repeated presentations, and whether the effect of novel stimuli varied as a function of the unit dose of amphetamine tested. Methods: Male rats were screened for their response in inescapable and free-choice novelty tests. Following initial training using a high unit dose of amphetamine (0.1 mg/kg per infusion), the dose was reduced (0.03 mg/kg per infusion), and novel stimuli were presented in the operant conditioning chamber on four separate sessions. In experiment 2, novel stimuli were presented during several sessions at a variety of amphetamine doses (0.003, 0.01, 0.03, and 0.056 mg/kg per infusion). Results: Four repeated presentations of novel stimuli reduced amphetamine self-administration with no significant loss in the effect of novel stimuli across repeated presentations. In experiment 2, novel stimuli reduced amphetamine self-administration at low unit doses (0.003 mg/kg and 0.01 mg/kg per infusion), and rats classified as HR based on their activity in inescapable novel stimuli were more disrupted by novel stimuli than LR rats. Conclusions: These results suggest that repeated presentation of novel stimuli can reduce amphetamine self-administration at low unit doses and that HR rats are more sensitive than LR rats to non-drug stimuli that compete with responding for amphetamine.