title: Cocaine is low on the value ladder of rats: possible evidence for resilience to addiction.
abstract: BACKGROUND
  Assessing the relative value of cocaine and how it changes with chronic drug use represents a long-standing goal in addiction research. Surprisingly, recent experiments in rats--by far the most frequently used animal model in this field--suggest that the value of cocaine is lower than previously thought.
  
  
  RESULTS
  Here we report a series of choice experiments that better define the relative position of cocaine on the value ladder of rats (i.e., preference rank-ordering of different rewards). Rats were allowed to choose either taking cocaine or drinking water sweetened with saccharin--a nondrug alternative that is not biologically essential. By systematically varying the cost and concentration of sweet water, we found that cocaine is low on the value ladder of the large majority of rats, near the lowest concentrations of sweet water. In addition, a retrospective analysis of all experiments over the past 5 years revealed that no matter how heavy was past cocaine use most rats readily give up cocaine use in favor of the nondrug alternative. Only a minority, fewer than 15% at the heaviest level of past cocaine use, continued to take cocaine, even when hungry and offered a natural sugar that could relieve their need of calories.
  
  
  CONCLUSIONS
  This pattern of results (cocaine abstinence in most rats; cocaine preference in few rats) maps well onto the epidemiology of human cocaine addiction and suggests that only a minority of rats would be vulnerable to cocaine addiction while the large majority would be resilient despite extensive drug use. Resilience to drug addiction has long been suspected in humans but could not be firmly established, mostly because it is difficult to control retrospectively for differences in drug self-exposure and/or availability in human drug users. This conclusion has important implications for preclinical research on the neurobiology of cocaine addiction and for future medication development.
authors.affiliation: Unité Mixte de Recherche 5227, Centre National de la Recherche Scientifique, Université Victor Segalen Bordeaux 2, Bordeaux, France.
authors.forename: Lauriane
authors.initials: L
authors.lastname: Cantin
authors.forename: Magalie
authors.initials: M
authors.lastname: Lenoir
authors.forename: Eric
authors.initials: E
authors.lastname: Augier
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vanhille
authors.forename: Sarah
authors.initials: S
authors.lastname: Dubreucq
authors.forename: Fuschia
authors.initials: F
authors.lastname: Serre
authors.forename: Caroline
authors.initials: C
authors.lastname: Vouillac
authors.forename: Serge H
authors.initials: SH
authors.lastname: Ahmed
mesh_terms: D000818:Animals; D016739:Behavior, Addictive / Q000523:psychology; D002755:Choice Behavior / Q000187:drug effects; D003042:Cocaine / Q000008:administration & dosage / Q000009:adverse effects*; D019970:Cocaine-Related Disorders / Q000523:psychology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012439:Saccharin / Q000008:administration & dosage
chemical_list: D012439:Saccharin; D003042:Cocaine