Harris R A, Snell D, Loh H H
J Pharmacol Exp Ther. 1978 Jan;204(1):103-17.
The effects of 16 drugs were studied in rats responding under fixed-ratio (FR 30) and fixed-interval (FI 2 minute) schedules of food presentation. The drugs tested included lysergic acid diethylamide (LSD), dimethyltryptamine, mescaline, d-amphetamine and 12 methoxylated amphetamines. All of the drugs decreased the average rates of responding under both schedules, but their potencies varied widely. For example, with LSD, the most potent drug tested, doses of 0.1 to 0.3 mg/kg were sufficient to reduce responding while with dimethyltryptamine and mescaline, doses of 10 to 30 mg/kg were required to clearly reduce responding. For the 12 drugs which are known to produce hallucinogenic effects, their potencies in reducing responding were positively correlated with their reported potencies in producing these subjective effects in humans. Although all of the drugs decreased the average rates of responding, alterations in the patterns of responding under the FR and FI schedules varied among the drugs. Analysis of responding under the FI schedule indicated that d-amphetamine, m-methoxyamphetamine, p-methoxyamphetamine, LSD and 3,4-methylenedioxyamphetamine generally increased the low rates of responding occurring at the beginning of each interval and decreased the high rates of responding occurring later in each interval (rate-dependent effects). The other drugs generally decreased responding throughout the interval. These results are discussed in terms of the known neurochemical effects of these drugs.
在以固定比率（FR 30）和固定间隔（FI 2分钟）呈现食物的条件下，对大鼠进行了16种药物效果的研究。所测试的药物包括麦角酸二乙酰胺（LSD）、二甲基色胺、三甲氧苯乙胺、右旋苯丙胺和12种甲氧基化苯丙胺。所有药物均降低了两种条件下的平均反应率，但它们的效力差异很大。例如，LSD是所测试的效力最强的药物，0.1至0.3毫克/千克的剂量就足以降低反应，而二甲基色胺和三甲氧苯乙胺则需要10至30毫克/千克的剂量才能明显降低反应。对于已知会产生致幻作用的12种药物，它们降低反应的效力与据报道在人体产生这些主观效应的效力呈正相关。尽管所有药物均降低了平均反应率，但FR和FI条件下反应模式的改变在不同药物之间有所不同。对FI条件下反应的分析表明，右旋苯丙胺、间甲氧基苯丙胺、对甲氧基苯丙胺、LSD和3,4-亚甲基二氧基苯丙胺通常会增加每个间隔开始时出现的低反应率，并降低每个间隔后期出现的高反应率（速率依赖性效应）。其他药物通常在整个间隔期内降低反应。根据这些药物已知的神经化学效应讨论了这些结果。
