Université de Bordeaux, Institut des Maladies Neurodégénératives, Rue Léo-Saignat, Bordeaux, France.
Neuropsychopharmacology. 2013 Jun;38(7):1209-20. doi: 10.1038/npp.2013.17. Epub 2013 Jan 15.
Epidemiological research shows that the proportion of drug users who become addicted to heroin is higher than to cocaine. Here we tested whether this difference could be due to a difference in the addiction liability between the two drugs. Addiction liability was assessed under a discrete-trials choice procedure by measuring the proportion of rats that prefer the drug over a potent alternative reward (ie, water sweetened with saccharin). Previous research on choice between self-administration of i.v. cocaine or sweet water showed that the proportion of cocaine-preferring rats remains relatively low and invariable (ie, 15%), even after extended drug access and regardless of past drug consumption (ie, total drug use before choice testing). By contrast, the present study shows that under similar choice conditions, the proportion of heroin-preferring rats considerably increases with extended heroin access (6-9 h per day for several weeks) and with past heroin consumption, from 11 to 51% at the highest past drug consumption level. At this level, the proportion of drug-preferring rats was about three times higher with heroin than with cocaine (51% vs 15%). This increase in the rate of heroin preference after extended heroin access persisted even after recovery from acute heroin withdrawal. Overall, these findings show that choice procedures are uniquely sensitive to different drugs and suggest that heroin is more addictive than cocaine. This higher addiction liability may contribute to explain why more drug users become addicted to heroin than to cocaine in epidemiological studies.
流行病学研究表明，吸毒者成瘾海洛因的比例高于可卡因。在这里，我们测试了这种差异是否可以归因于两种药物成瘾性的差异。成瘾性通过测量大鼠在离散试验选择程序中对药物的偏好比例来评估，即测量大鼠对药物（即糖精加糖的水）的偏好与对强力替代奖励（即糖精加糖的水）的偏好的比例。以前关于静脉内可卡因或甜水自我给药之间选择的研究表明，即使在延长药物接触和不考虑过去药物消耗（即在选择测试之前的总药物使用）的情况下，喜欢可卡因的大鼠的比例仍然相对较低且不变（即 15%）。相比之下，本研究表明，在类似的选择条件下，随着延长海洛因接触（每天 6-9 小时，持续数周）和过去海洛因消耗的增加，喜欢海洛因的大鼠的比例大大增加，从最高过去药物消耗水平的 11%增加到 51%。在这个水平上，喜欢海洛因的大鼠的比例比可卡因高约三倍（51%比 15%）。这种在延长海洛因接触后海洛因偏好率的增加甚至在急性海洛因戒断后恢复后仍持续存在。总的来说，这些发现表明选择程序对不同药物具有独特的敏感性，并表明海洛因比可卡因更具成瘾性。这种更高的成瘾性可能有助于解释为什么在流行病学研究中，更多的吸毒者对海洛因成瘾而不是可卡因成瘾。
