Effects of acute and chronic nicotine on impulsive choice in rats
Effects of acute and chronic nicotine on impulsive choice in rats
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DOI：
10.1097/00008877-200502000-00002
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发表时间：
2005-02-01
影响因子：
1.6
通讯作者：
Locey, ML
中科院分区：
文献类型：
--
作者：
Dallery, J;Locey, ML
冲动选择，或对小的即时强化物的偏好超过大的延迟强化物，与吸烟有关。尼古丁对实验动物冲动选择的直接影响尚不清楚。我们检查了急性和慢性尼古丁注射以及注射终止对大鼠冲动选择的影响。在一个离散的试验过程中，五只老鼠在一粒和三粒强化物之间做出选择。对较小的强化器的延迟始终为1s。计算机将延迟调整为更大的强化物，直到选择模式反映出两个选项之间的冷漠。我们评估了急性和慢性尼古丁（对照，0.03、0.1、0.3和1.0 mg/kg尼古丁）的影响。急性剂量为1.0 mg/kg时，产生第一反应的潜伏期增加。在选择之间的延迟期间，急性和慢性尼古丁对反应潜伏期和杠杆按压的影响没有一致的差异。急性注射尼古丁剂量依赖性增加冲动反应。在慢性注射后，冲动反应与剂量无关，即使在没有尼古丁的情况下也会增加。在停止注射药物后，在大约30个无药物疗程中，行为仍保持冲动，然后反应逐渐恢复到基线水平。结果表明，冲动选择的增加不是由于厌食效应、反应偏差或条件强化的变化。尼古丁可能降低了延迟强化物的价值。长期暴露于尼古丁中会产生长期但可逆的冲动选择增加。
Impulsive choice, or preference for small immediate reinforcers over large delayed reinforcers, has been associated with cigarette smoking. The direct effects of nicotine on impulsive choice in laboratory animals are unknown. We examined the effects of acute and chronic nicotine injections, and the termination of injections, on impulsive choice in rats. Five rats made choices between a one- and a three-pellet reinforcer in a discrete trials procedure. The delay to the smaller reinforcer was always 1 s. A computer adjusted the delay to the larger reinforcer until the pattern of choices reflected indifference between the two alternatives. We assessed the effects of acute and chronic nicotine (vehicle, 0.03, 0.1, 0.3 and 1.0 mg/kg nicotine). The latency to make the first response of the session increased under the acute 1.0 mg/kg dose. There were no consistent differences in the effects of acute and chronic nicotine on response latency and lever pressing during the delays between choices. Acute injections of nicotine dose-dependently increased impulsive responding. After chronic injections, impulsive responding was increased equivalently regardless of dose, and it was increased even in the absence of nicotine. After drug injections were terminated, behavior remained impulsive for about 30 drug-free sessions, and then responding gradually returned to baseline levels. The results suggest that increases in impulsive choice were not due to anorectic effects, response biases or changes in conditioned reinforcement. Nicotine may have decreased the value of delayed reinforcers. Chronic nicotine exposure produced long-lasting but reversible increases in impulsive choice.