Department of Psychology and Collaborative Program in Neuroscience, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Learn Mem. 2019 Jan 16;26(2):46-55. doi: 10.1101/lm.048579.118. Print 2019 Feb.
To test the hypothesis that drugs of abuse and their conditioned stimuli (CSs) enhance memory consolidation, the effects of post-training exposure to cocaine and nicotine were compared to the effects of post-training exposure to contextual stimuli that were paired with the effects of these drugs. Using the object recognition (OR) task, it was first demonstrated that both 10 and 20 mg/kg cocaine, and 0.2 and 0.4 mg/kg nicotine, enhanced recognition memory when administered immediately after, but not 6 h after the sample phase. To establish the drug CSs, rats were confined for 2 h in a chamber (the CS+) after injections of 20 mg/kg cocaine, or 0.4 mg/kg nicotine, and in another chamber (the CS-) after injections of vehicle. This was repeated over 10 d (5 drug/CS+ and 5 vehicle/CS- pairings in total). At the end of this conditioning period, when tested in a drug-free state, rats displayed conditioned hyperactivity in the CS+ relative to the CS-. More important, immediate, but not delayed, post-sample exposure to the cocaine CS+, or nicotine CS+, enhanced OR memory. Therefore, this study reports for the first time that contextual stimuli paired with cocaine and nicotine, like the drugs themselves, have the ability to enhance memory consolidation.
为了验证滥用药物及其条件刺激（CSs）增强记忆巩固的假设，比较了训练后暴露于可卡因和尼古丁与与这些药物的作用相关联的环境刺激（contextual stimuli）的暴露后对记忆巩固的影响。使用物体识别（OR）任务，首先证明 10 和 20 mg/kg 可卡因和 0.2 和 0.4 mg/kg 尼古丁在注射后立即给药，但不在样本阶段 6 小时后给药时，增强了识别记忆。为了建立药物 CSs，在注射 20 mg/kg 可卡因或 0.4 mg/kg 尼古丁后，将大鼠限制在一个室（CS+）中 2 小时，在另一个室（CS-）中限制在车辆后。这在 10 天内重复进行（总共 5 次药物/CS+和 5 次载体/CS-配对）。在这个条件作用期结束时，在无药物状态下进行测试时，大鼠在 CS+中表现出相对于 CS-的条件性过度活跃。更重要的是，立即但不是延迟的样本后暴露于可卡因 CS+或尼古丁 CS+增强了 OR 记忆。因此，本研究首次报道了与可卡因和尼古丁配对的环境刺激，与药物本身一样，具有增强记忆巩固的能力。
